WorldWideScience

Sample records for mackinac bridge spans

  1. Long Span Bridges in Scandinavia

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1998-01-01

    The first Scandinavian bridge with a span of more than 500 m was the Lillebælt Suspension Bridge opened to traffic in 1970.Art the end of the 20th century the longest span of any European bridge is found in the Storebælt East Bridge with a main span of 1624 m. Also the third longest span in Europe...... is found in Scandinavia - the 1210 m span of the Höga Kusten Bridge in Sweden.The Kvarnsund Bridge in Norway was at the completion in 1991 the longest cable-stayed bridge in the world, and the span of 530 m is still thge longest for cable-stayed bridges in concrete. The Øresund Bridge with its sapn of 490...... m is the longest among cable-stayed bridges for both road and railway traffic....

  2. Incidence of bark- and wood-boring insects in firewood: a survey at Michigan's Mackinac Bridge.

    Science.gov (United States)

    Haack, Robert A; Petrice, Toby R; Wiedenhoeft, Alex C

    2010-10-01

    Firewood is a major pathway for the inadvertent movement of bark- and wood-infesting insects. After discovery of Agrilus planipennis Fairmaire (Coleoptera: Buprestidae) in southeastern Michigan in 2002, quarantines were enacted including prohibition of transporting firewood across the Mackinac Bridge between Michigan's Lower and Upper peninsulas. Drivers are required to surrender firewood before crossing the bridge. We surveyed recently surrendered firewood in April, July, and September 2008 and categorized it by genus, cross-sectional shape (whole, half, or quarter), approximate age (years since it was a live tree), presence of bark, and evidence of bark- and wood-boring insects. The 1045 pieces of firewood examined represented 21 tree genera: primarily Acer (30%), Quercus (18%), Fraxinus (15%), Ulmus (12%), Betula (5%), and Prunus (5%). Live borers (Bostrichoidea, Brentidae, Buprestidae, Cerambycidae, Cossidae, Curculionidae [Scolytinae and non-Scolytinae], and Siricidae) were found in 23% of the pieces and another 41% had evidence of previous borer infestation. Of the 152 Fraxinus firewood pieces, 13% had evidence of past A. planipennis infestation, but we found no live A. planipennis. We discuss national "don't move firewood" campaigns and U.S. imports of fuelwood. During 1996-2009, the United States imported fuelwood valued at > dollars U.S. 98 million from 34 countries.

  3. 23 CFR 650.809 - Movable span bridges.

    Science.gov (United States)

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Movable span bridges. 650.809 Section 650.809 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION ENGINEERING AND TRAFFIC OPERATIONS BRIDGES, STRUCTURES, AND HYDRAULICS Navigational Clearances for Bridges § 650.809 Movable span bridges. A fixed...

  4. Seismic Performance of Multi-Span RC Railway Bridges

    DEFF Research Database (Denmark)

    Georgakis, Christos; Barrau, Xavier

    2008-01-01

    Presently, there is no clear method for determining the optimal railway bridge design for a particular ground type and expected seismic intensity. Four main types of RC bridge dominate the current multi-span railway bridge design trends – the Simply Supported Beam, Continuous Box-Girder (CBG), CBG...

  5. Aerodynamic challenges in span length of suspension bridges

    Institute of Scientific and Technical Information of China (English)

    XIANG Haifan; GE Yaojun

    2007-01-01

    The potential requirement of extreme bridge spans is firstly discussed according to horizontal clearances for navigation and economical construction of deep-water foundation. To ensure the technological feasibility of suspen- sion bridges with longer spans, the Static estimation of feasi- ble span length is then made based on current material strength and weight of cables and deck. After the performances of the countermeasures for raising the aerodynamic stability are reviewed, a trial design of a 5 000 m suspension bridge, which is estimated as a reasonable limitation of span length, is finally conducted to respond to the tomorrow's challenge in span length of suspension bridges with the particular aspects, including dynamic stiffness, aerodynamic flutter and aerostatic stability.

  6. Evaluating the life cycle environmental impact of short span bridges

    DEFF Research Database (Denmark)

    Du, Guangli; Pettersson, Lars; Karoumi, Raid

    2016-01-01

    impact of the construction sector. Life cycle assessment (LCA) is a systematic method for assessing the environmental impact of products and systems, but its application in bridges is scarce. In Swede, most of the bridges are short spans and the type of concrete slab-frame bridge (CFB) accounts......Bridge infrastructure consumes large amount of energy and raw materials, leading to considerable environmental burdens. The traditional infrastructure construction prioritizes its technical and economic viability. In recent years, the society devotes an ever-increased attention to the environmental...... for a large share. Soil steel composite bridge (SSCB) is a functional equivalent solution for CFB. In order to mitigate the environmental burdens of short span bridges, this paper performed a comparative LCA study between these two types of bridge. The results indicate that the initial material consumption...

  7. Advanced aerostatic analysis of long-span suspension bridges

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    As the span length of suspension bridges increases, the diameter of cables and thus the wind load acting on them, the nonlinear wind-structure interaction and the wind speed spatial non-uniformity all increase consequently, which may have unnegligible influence on the aerostatic behavior of long-span suspension bridges. In this work, a method of advanced aerostatic analysis is presented firstly by considering the geometric nonlinearity, the nonlinear wind-structures and wind speed spatial non-uniformity. By taking the Runyang Bridge over the Yangtze River as example, effects of the nonlinear wind-structure interaction, wind speed spatial non-uniformity, and the cable's wind load on the aerostatic behavior of the bridge are investigated analytically. The results showed that these factors all have important influence on the aerostatic behavior, and should be considered in the aerostatic analysis of long and particularly super long-span suspension bridges.

  8. Long span cable supported bridges - present technology and trends

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1998-01-01

    The activity within the field of long-span cable supported bridges has never been larger than at the end of the 20th century. The technology is well advanced to cope with the present challenges but it is also approaching its limits so if the trend towards ever increasing spans continues...... into the next century, further developments are required to ensure that the bridges will be stable, durable and constructible....

  9. Construction Technology of Long Span Bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    2000-01-01

    A large variety of construction methods are used during construction of major bridges, and in many cases the final structural system must be chosen with due respect to the construction process. Today the preferred construction methods are: the free-cantilever method, the launching method and the ......A large variety of construction methods are used during construction of major bridges, and in many cases the final structural system must be chosen with due respect to the construction process. Today the preferred construction methods are: the free-cantilever method, the launching method...

  10. Progressive collapse susceptibility of a long span suspension bridge

    DEFF Research Database (Denmark)

    Olmati, Pierluigi; Giuliani, Luisa

    2013-01-01

    ones may lead to subsequent failures. In suspension bridges, which are characterized by a relatively low continuity of the system, the damage of the deck may favor a collapse standstill, in case of an early detachment of the deck collapsing section. In the paper, a long span suspension bridge is taken...

  11. Probabilistic traffic load model for short-span city bridges

    NARCIS (Netherlands)

    Hellebrandt, L.; Blom, C.B.M.; Steenbergen, R.D.J.M.

    2014-01-01

    In the coming years numerous existing traffic bridges in cities are subject to re-evaluation. In this paper a new probabilistic traffic load model for short-span bridges is proposed. As an example, site-specific weigh-in-motion data from Rotterdam, the Netherlands, is included in the model. The

  12. Assistant pullback technique for main span closure of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Chen Ming; Luo Chengbin; Wu Qihe; Zhang Yongtao; You Xinpeng

    2009-01-01

    Sutong Bridge is a cable-stayed steel box girder bridge with a main span of 1 088 m. The erection of upper structure adopts geometry control method and requires no change to the unit's size and the structure's none-stress geometry. Before main span closure, the cantilever of girder reaches 540.8 m, the structure state is noticeably influenced by external circumstances, the main span closure face great difficulty. By abstracting the advantage of the pullback method abroad and the domestic temperature-cutting method, a new assistant pullback method have put forward and bring into practice actually. In this paper, the analysis key point of practice conditions, key parameter of practice, main measures of the method and the performance is introduced.

  13. State-of-the-art of long-span bridge engineering in China

    Institute of Scientific and Technical Information of China (English)

    XIANG Haifan; GE Yaojun

    2007-01-01

    This paper introduces the state-of-the-art of long-span bridge engineering in China with emphases on recent long-span bridge projects,bridge deck configuration and material,design codes of long-span bridges and improvement of aerodynamic performance.The recent long-span bridge projects include thirty-eight completed suspension bridges,cable-stayed and arch bridges with a main span over 400 m,and eighteen major bridges are under construction.The bridge deck configuration and material,with prestressed concrete decks,steel-concrete composite decks and steel box decks together with several popular cross-sections,are presented.The third part briefly outlines four design codes,including static and dynamic design for highway long-span bridges,and the recent engineering experiences gained from several aerodynamic vibration control projects of long-span bridges are shared in the last part.

  14. Impact Coefficient Analysis of Long-Span Railway Cable-Stayed Bridge Based on Coupled Vehicle-Bridge Vibration

    OpenAIRE

    Yongle Li; Shifu Dong; Yulong Bao; Kejian Chen; Shizhong Qiang

    2015-01-01

    Compared with medium and small span bridges, very limited attention has been paid on the research of the impact coefficient of long-span railway bridges. To estimate the impact effects of long-span railway bridges subjected to moving vehicles, a real long-span railway cable-stayed bridge is regarded as the research object in this study, and a coupled model of vehicle-bridge system is established. The track irregularities are taken as the system excitation and the dynamic responses of the vehi...

  15. A review of long-span suspension bridges: a case of Akashi-Kaikyo ...

    African Journals Online (AJOL)

    A review of long-span suspension bridges: a case of Akashi-Kaikyo and Runyang ... bridge ever built, and the greatest bridge in the beginning of the new Millennium. These bridges contain remarkable features of novel bridge construction ...

  16. Study of the aerostatic and aerodynamic stability of super long-span cable-stayed bridges

    Institute of Scientific and Technical Information of China (English)

    Zhang Xinjun; Sun Hailing

    2014-01-01

    With the increase of span length,the bridge tends to be more flexible,and the wind stability be-comes an important problem for the design and construction of super long-span cable-stayed bridges. By taking a super long-span cable-stayed bridge with a main span of 1 400 m as example,the aerostatic and aerodynamic stability of the bridge are investigated by three-dimensional nonlinear aerostatic and aerodynamic stability analy-sis,and the results are compared with those of a suspension bridge with a main span of 1 385 m,and from the aspect of wind stability,the feasibility of using cable-stayed bridge in super long-span bridge with a main span above 1 000 m is discussed. In addition,the influences of design parameters including the depth and width of the girder,the tower structure,the tower height-to-span ratio,the side-to-main span ratio,the auxiliary piers in the side span and the anchorage system of stay cables,etc on the aerostatic and aerodynamic stability of su-per long-span cable-stayed bridges are investigated numerically;the key design parameters are pointed out,and also their reasonable values are proposed.

  17. Limit span of self-anchored cable-stayed suspension cooperation system bridge based on strength

    Institute of Scientific and Technical Information of China (English)

    Zhe ZHANG; Huili WANG; Sifeng QIN; Xiaomeng GE

    2009-01-01

    The limit span of self-anchored cable-stayed suspension bridge is deduced. The relations among the geometrical parameters, loads and material characteristics are also analyzed. Based on the material strength and commonly used materials, the limit spans of self-anchored cable-stayed suspension bridges with concrete girder or steel girder under vertical static load are discussed in detail.The corresponding upper limit spans and the effect of the factors on the span are given. The results indicate that increasing rise-span ratio, height-span ratio and cable-stayed segment length or reducing the second dead load could increase the cooperation system span.

  18. Impact Coefficient Analysis of Long-Span Railway Cable-Stayed Bridge Based on Coupled Vehicle-Bridge Vibration

    Directory of Open Access Journals (Sweden)

    Yongle Li

    2015-01-01

    Full Text Available Compared with medium and small span bridges, very limited attention has been paid on the research of the impact coefficient of long-span railway bridges. To estimate the impact effects of long-span railway bridges subjected to moving vehicles, a real long-span railway cable-stayed bridge is regarded as the research object in this study, and a coupled model of vehicle-bridge system is established. The track irregularities are taken as the system excitation and the dynamic responses of the vehicle-bridge system are calculated. The impact effects on main girder, stayed cable, bearings, and bridge tower are discussed at various vehicle speeds. The results show that different components of the long-span railway cable-stayed bridge have different impact coefficients. Even for each part, the impact coefficient is also different at different local positions. It reveals that the impact coefficients in the actual situation may have significant differences with the related code clauses in the present design codes.

  19. The mechanical response of multi-tower continuous-span suspension bridge deck pavement based on whole bridge analysis

    Institute of Scientific and Technical Information of China (English)

    Li Hongtao; Zhang Chenchen; Hu Jing; Qian Zhendong

    2011-01-01

    The effect of multiple span suspension structure on the mechanical response of bridge deck pavement was studied, and finite element analysis (FEM) of stress and strain of pavement according to the bridge floor system features of super-long and high flexibility was made. Meanwhile, the FEM results were compared with those of the single span suspension structure. Three-stage analytic hierarchy process (AHP) is developed to analyze the mechanical response including whole bridge analysis, partial beams section analysis and orthotropic plate analysis. The most unfavorable load position was determined by the numerical solutions acquired from each stage to study the main mechanical index of multiple span suspension structure. The FEM results showed that the mechanical response numerical solutions by using the three-stage AHP are greater than those by simplified boundary condition, and the force condition of multiple span suspension structure is worse than that of the single span suspension structure.

  20. Seismic performance evaluation for super-long span cable-stayed bridges

    Institute of Scientific and Technical Information of China (English)

    Ye Aijun; Wu Shouchang

    2009-01-01

    Based on the capacity/demand (C/D) analysis of bridge components, and life cycle and performance based seismic design principles, a practical approach is developed for the seismic performance evaluation of super-long span cable-stayed bridges. According to the approach, the seismic performance evaluation of the Sutong Bridge, which is a cable-stayed bridge with a main span of 1 088 m, is completed, and the practicality of the approach is validated. The earthquake resistance level for super-long span cable-stayed bridges is discussed, including the earthquake level, its corresponding structural performance and check indices. And a set of formula for capacity/demand ratio calculation of bridge components is proposed.

  1. A Proposal for 4000m-span Cable-stayed Suspension Bridge

    Directory of Open Access Journals (Sweden)

    Haijun Wang

    2013-06-01

    Full Text Available This study proposed a compound bridge of suspension bridges and cable-stayed bridges with 4000 m super-long-span over the Tsugaru Strait, Japan. Near to the main towers, cable-stayed bridges and prestressed concrete decks are proposed. It is helpful to enhance rigidity and endure the great axial compression force. In the center of the span, suspension bridges and steel box decks are stiffened by trusses, it can reduce self-weigh and the space between girders, thus contribute to aero-elastic stability. RCFT main tower, RC shell pier and RCFT jacket foundation can enhance rigidity and reduce self-weigh. As a result, the live-dead load ratio of proposal is 0.05 and it is equivalent to 2500m-span suspension bridge.

  2. Case Study on 4000 m-span Cable-stayed Suspension Bridge

    Directory of Open Access Journals (Sweden)

    Haijun Wang

    2014-04-01

    Full Text Available This study describes the case studies for a cable-stayed suspension bridges proposed over the Tsugaru Strait, Japan. Center Bridge is designed as a compound bridge of suspension bridges and cable-stayed bridges with 4000 m super-long-span. Case studies about the effects of cable-stayed bridge length, the design of sub-cable, height and stiffness of main tower, type of foundation and length of side span on displacement were carried out. With appropriate design of above parameters, the compound bridge can reduce horizontal displacement of main tower and vertical deflection in the central portion and enhance resistance to partial loading. The study reports the results based on these case studies.

  3. Non-stationary Buffeting Response Analysis of Long Span Suspension Bridge Under Strong Wind Loading

    Institute of Scientific and Technical Information of China (English)

    Wenfeng Huang; Kongqing Zou

    2016-01-01

    The non⁃stationary buffeting response of long span suspension bridge in time domain under strong wind loading is computed. Modeling method for generating non⁃stationary fluctuating winds with probabilistic model for non⁃stationary strong wind fields is first presented. Non⁃stationary wind forces induced by strong winds on bridge deck and tower are then given a brief introduction. Finally, Non⁃stationary buffeting response of Pulite Bridge in China, a long span suspension bridge, is computed by using ANSYS software under four working conditions with different combination of time⁃varying mean wind and time⁃varying variance. The case study further confirms that it is necessity of considering non⁃stationary buffeting response for long span suspension bridge under strong wind loading, rather than only stationary buffeting response.

  4. A Modal Pushover Analysis on Multi-Span Concrete Bridges to Estimate Inelastic Seismic Responses

    Directory of Open Access Journals (Sweden)

    Pennung Warnitchai

    2007-01-01

    Full Text Available The performance of Modal Pushover Analysis (MPA in predicting the inelastic seismic response of multi-span concrete bridges is investigated. The bridge is subjected to lateral forces distributed proportionally over the span of the bridge in accordance to the product of mass and displaced shape. The bridge is pushed up to the target displacement determined from the peak displacement of the nth mode inelastic Single Degree of Freedom System derived from Uncoupled Modal Response History Analysis (UMRHA. The peak response from each mode is combined using Square-Root of Sum-of-Square (SRSS rule. Although the use of SRSS rule is not appropriate in this bridge and the displaced pattern is shifted from the elastic shape due to yielding, MPA can predict well the total peak response of the bridge in inelastic range.

  5. Research development of digital maintenance and management system for long-span cable-stayed bridges

    Institute of Scientific and Technical Information of China (English)

    REN Yuan; HUANG Qiao; SUN Yong-ming

    2009-01-01

    Digital cable-stayed bridge maintenance and management system (DCBMS) was developed for the need of maintenance and management of long-span cable-stayed bridges. In this paper, the major functions and theoretical application of eight modules were systematically stated with the background of Harbin Songhua River cable-stayed bridge, which include data management module, inspection and measurement module, assessment module, finite element analysis module, disease diagnosis and prediction module, maintenance module, query module and help module. By analyzing and calculating the data from manual inspection database, basic database and health monitoring subsystem, DCBMS can accomplish the functions like life prediction, disease diagnosis, comprehensive assessment, maintenance and management of bridges. Therefore, the maintenance and management of long-span cable-stayed bridges can be made digital, professional and scientific. By running this system, a real-time and specific technical guidance can be provided for the maintainers and managers of longspan cable-stayed bridges.

  6. Aerostatic Stability of Long-Span Cable-Stayed Bridges: Parametric Study

    Institute of Scientific and Technical Information of China (English)

    程进; 江见鲸; 肖汝诚; 项海帆

    2003-01-01

    The increasing span of cable-stayed bridges has focused more attention on the aerostatic stability of the design and construction of such bridges. This paper presents a new method to analyze the nonlinear aerostatic stability of cable-stayed bridges including all three components of the wind load and the geometric nonlinearity. The analysis was used to investigate the effects of the wind angle of incidence, the wind load of individual bridge elements, the sagging of cable elements, the changes of tower height and the changes of side span length on the aerostatic stability of cable-stayed bridges. The results show that the wind angle of incidence and the wind loads on the cables have an important effect on the aerostatic stability of cable-stayed bridges.

  7. GPS Dynamic Monitoring Experiment and Result Analysis of Long-Span Cable-Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    For the sake of timely appraising the working condition of the bridge, measuring the dynamic characteristics of the bridge structure is very important and necessary. A GPS dynamic monitoring test was carried out in the Wuhan Baishazhou Bridge, which is one of the longest span cable-stayed bridges having been built in China. This paper introduces the experimental implementing scheme and data processing method. The vibration characteristics of the middle span of cable-stayed bridge are availably obtained by use of the spectral analytic approach. The measuring results are very identical to the theoretical designed values. The research demonstrates that, with GPS receiver of the high sampling rate and suitable data processing method, the vibration characteristics of the bridge structure can be determined with high accuracy.

  8. Non-Flutter Design Principle for long Span Bridges

    DEFF Research Database (Denmark)

    Johansson, Jens; Andersen, Michael Styrk; Starch Øvre, Michele

    velocity for a thin airfoil shows an asymptotical behavior. In traditional bridge design the torsional-to-vertical frequency ratio is increased to obtain higher flutter wind velocities. In the present study, we investigate, what we will label the non-flutter design principle, in which the torsional...

  9. Coating of long span bridges; Chotaikyo no toso

    Energy Technology Data Exchange (ETDEWEB)

    Kawanishi, H. [Nippon Paint Co. Ltd., Osaka (Japan)

    1998-11-15

    A composite anti-corrosion coating method (zinc rich primer + epoxy resin primer + polyurethane resin primer) was used for the Seto Ohashi Bridge. The anti-corrosion coating system in the Akashi Ohashi Bridge is the same as described above. This paper mainly describes the coating in a Honshu-Shikoku linking bridge. In the coating system, product blasting is used as rough coating. In the whole process, coating is basically performed at the factory. The anti-corrosion against a friction junction plane and splice plate is also carried out. For example, a rustproof bolt is used in the easy-to-corrode part. Coating is performed to obtain a thick film of more than 200 {mu}m. The edge of a member is rounded. The zinc dust in a zinc rich primer performs sacrifice anti-corrosion. The outside-air isolation film uses an epoxy resin primer that is excellent in water resistance and chemical resistance. This film improves the anti-corrosion effect by isolating the moisture or corrosive substance that permeates through the coated film from the outside air. If the weather resistance of the fluoroethylene resin primer used instead of a polyurethane resin primer has final coating quality as expected, the maintenance cycle in an offshore bridge can be more extended than the current cycle of about 10 to 15 years. 1 ref., 1 fig., 5 tabs.

  10. Measurement of Temperature Fields in Long Span Concrete Bridges

    Directory of Open Access Journals (Sweden)

    J. Římal

    2001-01-01

    Full Text Available This paper deals with assesing of the influence of climate temperatures on deformations and stresses in a cross section of the Nusle Bridge. The main purpose is to describe the measurement of the thermal fields, to compare measured and computed temperature fields, and to provide a real estimation of the stresses that occur.

  11. Computer Simulation of Dynamic Interactions Between Vehicle and Long Span Box Girder Bridges

    Institute of Scientific and Technical Information of China (English)

    Lei Gong; Moe S.Cheung

    2008-01-01

    Moving vehicle loads,associated with roadway traffic can induce significant dynamic effects on the structural behaviours of bridges,especially for long-span bridges.The main objective of current research is to study traffic induced dynamic responses of long-span box-girder bridges.The finite element method has been employed in this study to obtain a three-dimensional mathematical model for the bridge system.For vehicle-bridge dynamic interaction analysis,the vehicle is modeled as a more realistic three-axle,six-wheel system,and the corresponding dynamic interaction equations have been derived.The bridge-vehicle inter- action is affected by many factors.The current study has been focused on such factors as:vehicle speed, vehicle damping ratio,multiple traffic lanes,mass ratio of vehicle and bridge,and dynamic characteristics of bridge.Case studies have been conducted to investigate these factors by using several box girder bridge examples including Confederation Bridge,the longest box girder bridge in the world.

  12. Seismic spatial effects on dynamic response of long-span bridges in stationary inhomogeneous random fields

    Institute of Scientific and Technical Information of China (English)

    林家浩; 张亚辉; 赵岩

    2004-01-01

    The seismic analysis of long-span bridges subjected to multiple ground excitations is an important problem.The conventional response spectrum method neglects the spatial effects of ground motion, and therefore may result in questionable conclusions. The random vibration approach has been regarded as more reliable. Unfortunately, so far,computational difficulties have not yet been satisfactorily resolved. In this paper, an accurate and efficient random vibration approach - pseudo excitation method (PEM), by which the above difficulties are overcome, is presented. It has been successfully used in the three dimensional seismic analysis of a number of long-span bridges with thousands of degrees of freedom and dozens of supports. The numerical results of a typical bridge show that the seismic spatial etfects, particularly the wave passage effect, are sometimes quite important in evaluating the safety of long-span bridges.

  13. Seismic spatial effects on dynamic response of long-span bridges in stationary inhomogeneous random fields

    Science.gov (United States)

    Jiahao, Lin; Yahui, Zhang; Yan, Zhao

    2004-12-01

    The seismic analysis of long-span bridges subjected to multiple ground excitations is an important problem. The conventional response spectrum method neglects the spatial effects of ground motion, and therefore may result in questionable conclusions. The random vibration approach has been regarded as more reliable. Unfortunately, so far, computational difficulties have not yet been satisfactorily resolved. In this paper, an accurate and efficient random vibration approach — pseudo excitation method (PEM), by which the above difficulties are overcome, is presented. It has been successfully used in the three dimensional seismic analysis of a number of long-span bridges with thousands of degrees of freedom and dozens of supports. The numerical results of a typical bridge show that the seismic spatial effects, particularly the wave passage effect, are sometimes quite important in evaluating the safety of long-span bridges.

  14. Structural health monitoring of long-span suspension bridges using wavelet packet analysis

    Institute of Scientific and Technical Information of China (English)

    Ding Youliang; Li Aiqun

    2007-01-01

    During the service life of civil engineering structures such as long-span bridges, local damage at key positions may continually accumulate, and may finally result in their sudden failure. One core issue of global vibration-based health monitoring methods is to seek some damage indices that are sensitive to structural damage. This paper proposes an online structural health monitoring method for long-span suspension bridges using wavelet packet transform (WPT). The WPTbased method is based on the energy variations of structural ambient vibration responses decomposed using wavelet packet analysis. The main feature of this method is that the proposed wavelet packet energy spectrum (WPES) has the ability to detect structural damage from ambient vibration tests of a long-span suspension bridge. As an example application, the WPES-based health monitoring system is used on the Runyang Suspension Bridge under daily environmental conditions. The analysis reveals that changes in environmental temperature have a long-term influence on the WPES, while the effect of traffic loadings on the measured WPES of the bridge presents instantaneous changes because of the nonstationary properties of the loadings. The condition indication indices VD reflect the influences of environmental temperature on the dynamic properties of the Runyang Suspension Bridge. The field tests demonstrate that the proposed WPES-based condition indication index VD is a good candidate index for health monitoring of long-span suspension bridges under ambient excitations.

  15. Structural health monitoring of long-span suspension bridges using wavelet packet analysis

    Science.gov (United States)

    Ding, Youliang; Li, Aiqun

    2007-09-01

    During the service life of civil engineering structures such as long-span bridges, local damage at key positions may continually accumulate, and may finally result in their sudden failure. One core issue of global vibration-based health monitoring methods is to seek some damage indices that are sensitive to structural damage. This paper proposes an online structural health monitoring method for long-span suspension bridges using wavelet packet transform (WPT). The WPT-based method is based on the energy variations of structural ambient vibration responses decomposed using wavelet packet analysis. The main feature of this method is that the proposed wavelet packet energy spectrum (WPES) has the ability to detect structural damage from ambient vibration tests of a long-span suspension bridge. As an example application, the WPES-based health monitoring system is used on the Runyang Suspension Bridge under daily environmental conditions. The analysis reveals that changes in environmental temperature have a long-term influence on the WPES, while the effect of traffic loadings on the measured WPES of the bridge presents instantaneous changes because of the nonstationary properties of the loadings. The condition indication indices V D reflect the influences of environmental temperature on the dynamic properties of the Runyang Suspension Bridge. The field tests demonstrate that the proposed WPES-based condition indication index V D is a good candidate index for health monitoring of long-span suspension bridges under ambient excitations.

  16. Numerical analysis of dynamic response of vehicle–bridge coupled system on long-span continuous girder bridge

    Directory of Open Access Journals (Sweden)

    Lipeng An

    2016-07-01

    Full Text Available To systematically study the vehicle–bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle–bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the “set-in-right-position” rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long-span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the “general code for design of highway bridges and culverts (China”. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle–bridge system.

  17. Vibration analysis of medium and small span bridges subjected to mixed marshalling freight trains

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    It has been reported several times that train derailment occurs when mixed marshalling freight trains traverse bridges at high speeds in China.This study aims to explain this phenomenon numerically based on the train-bridge coupling vibration theory and its associated computer program.The train-bridge vibration characteristic is analyzed by a computer program when mixed marshalling freight trains traverse 32-meter-span prestressed concrete simple beam bridges.The mechanism that dynamic responses of the bridges are prominent and that empty trains are inclined to derail are derived from the dynamic responses analysis.The analysis indicates that the significant differences of axle loads between heavy vehicles and empty vehicles produce periodic forced loadings of large amplitudes.These periodic loadings cause severe vibration of bridges.In turn,severe vibration of the bridges produces intensive counteraction to empty vehicles.

  18. Full implementations of structural health monitoring systems for long-span bridges and large-span domes

    Science.gov (United States)

    Li, Hui; Ou, Jinping

    2006-03-01

    In this paper, full implementations of structural health monitoring systems for long-span bridges and large-span domes are introduced. The frameworks of the health monitoring systems are introduced. The types and locations of sensors are also presented. The data acquisition system, including scheme of data acquisition system, strategies of collecting data, instrument and software used in the data acquisition system, is described. The data transmitting system, data management system and warning system are also designed. Based on the data collected by the structural health monitoring systems, response and dynamic properties of the structures, and the loads are statistically analyzed. Finite element (FE) model is updated based on the measured data by structural health monitoring.

  19. Analysis of Deflection Problems of Large-span Continuous Rigid Frame Bridge and Prevention Measures

    Directory of Open Access Journals (Sweden)

    Chen Dong

    2015-01-01

    Full Text Available The large-span continuous rigid frame bridge is a kind of common structural form in long-span bridges of our country, but one of the main diseases of these bridges is the excessive deflection in the mid-span, which seriously affects the safety of the structure. This paper makes a comprehensive analysis for the causes of the excessive deflection, and lists the commonly-used control measures in engineering. Simultaneously, new improvement measures and the comparative analysis of before-and-after improvements are put forward on this basis. However, these measures can be used to inhibit deflection in a certain extent, but cannot avoid the occurrence of deflection completely.

  20. Non-linear buffeting response analysis of long-span suspension bridges with central buckle

    Science.gov (United States)

    Wang, Hao; Li, Aiqun; Zhao, Gengwen; Li, Jian

    2010-06-01

    The rigid central buckle employed in the Runyang Suspension Bridge (RSB) was the first time it was used in a suspension bridge in China. By using a spectral representation method and FFT technique combined with measured data, a 3D fluctuating wind field considering the tower wind effect is simulated. A novel FE model for buffeting analysis is then presented, in which a specific user-defined Matrix27 element in ANSYS is employed to simulate the aeroelastic forces and its stiffness or damping matrices are parameterized by wind velocity and vibration frequency. A nonlinear time history analysis is carried out to study the influence of the rigid central buckle on the wind-induced buffeting response of a long-span suspension bridge. The results can be used as a reference for wind resistance design of long-span suspension bridges with a rigid central buckle in the future.

  1. Static and Dynamic Characteristics of a Long-Span Cable-Stayed Bridge with CFRP Cables

    Directory of Open Access Journals (Sweden)

    Xu Xie

    2014-06-01

    Full Text Available In this study, the scope of CFRP cables in cable-stayed bridges is studied by establishing a numerical model of a 1400-m span of the same. The mechanical properties and characteristics of CFRP stay cables and of a cable-stayed bridge with CFRP cables are here subjected to comprehensive analysis. The anomalies in the damping properties of free vibration, nonlinear parametric vibration and wind fluctuating vibration between steel cables and CFRP cables are determined. The structural stiffness, wind resistance and traffic vibration of the cable-stayed bridge with CFRP cables are also analyzed. It was found that the static performances of a cable-stayed bridge with CFRP cables and steel cables are basically the same. The natural frequencies of CFRP cables do not coincide with the major natural frequencies of the cable-stayed bridge, so the likelihood of CFRP cable-bridge coupling vibration is minuscule. For CFRP cables, the response amplitudes of both parametric vibration and wind fluctuating vibration are smaller than those of steel cables. It can be concluded from the research that the use of CFRP cables does not change the dynamic characteristics of the vehicle-bridge coupling vibration. Therefore, they can be used in long-span cable-stayed bridges with an excellent mechanical performance.

  2. Seismic Response of Long-Span Triple-Tower Suspension Bridge under Random Ground Motion

    Directory of Open Access Journals (Sweden)

    Chang-ke Jiao

    2017-01-01

    Full Text Available Multitower suspension bridge is of different style compared to the traditional suspension bridge with two towers, and consequently the dissimilarity of static and dynamic behaviors is distinct. As a special case of multitower suspension bridge, two long-span triple-tower suspension bridges have been constructed in China and the seismic random response of triple-tower suspension bridges is studied in this paper. A nonlinear dynamic analysis finite element model is established in ABAQUS and the Python language is utilized to facilitate the preprocess and postprocess during the finite element analysis. The procedure for random response calculation of structures based on the pseudoexcitation method is presented, with the initial equilibrium state of structure considered, which may be ignored for long-span bridges during calculating of stochastic response. The stationary seismic random responses of triple-tower suspension bridge under uniform excitation in firm, medium, and soft soil conditions and under spatially varying excitation in soft soil are investigated. The distribution of RMS of random responses of displacements and internal forces of the stiffening girder and towers is presented and discussed in detail. Results show that spatially variable ground motions should be considered in the stochastic analysis of triple-tower suspension bridge.

  3. Damage Detection for Long-Span Cable-Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhao Ling; Li Aiqun; Miao Changqing; Wang Yonglan

    2006-01-01

    Based on the updated finite-element model of a cable-stayed bridge, this study investigates the technique of identifying damage existing in cable or girder by means of numerical simulation. The modal analysis is performed to identify the changes in modal frequencies and curvatures caused by damage, and the static analysis is executed to detect the influence of damage on cable force. The results indicate a relatively significant decrease in frequencies of lower vertical bending modes due to the damage in cable and little change of frequencies due to damage in girder. Different sensitivities to the location of damaged cable are observed from the frequency changes of different bending modes, which can be used to initially locate the damaged cable. The damage in either cable or girder can be further localized by the most significant change in curvature of girder. The damage occurred in a cable produces a remarkable change in force of nearby cables, whereas the damage in girder brings little change of cable forces. In addition, a pragmatic approach for localizing the damage in girder or cable is proposed based on a comprehensive utilization of the changes in frequency of vertical bending modes, modal curvature of girder, and force in cables.

  4. Three-dimensional nonlinear flutter analysis of long-span suspension bridges during erection.

    Science.gov (United States)

    Zhang, Xin-jun; Sun, Bing-nan; Xiang, Hai-fan

    2003-01-01

    In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three-dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non-symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long-span suspension bridges during erection.

  5. Three-dimensional nonlinear flutter analysis of long-span suspension bridges during erection

    Institute of Scientific and Technical Information of China (English)

    张新军; 孙炳楠; 项海帆

    2003-01-01

    In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three-dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting result obtained was that the bridge was more stable when the stiffening girders were erected in a non-symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long-span suspension bridges during erection.

  6. Three-dimensional nonlinear flutter analysis of long-span suspension bridges during erection

    Institute of Scientific and Technical Information of China (English)

    张新军; 孙炳楠; 项海帆

    2003-01-01

    In this work, the aerodynamic stability of the Yichang Suspension Bridge over Yangtze River during erection was determined by three-dimensional nonlinear flutter analysis, in which the nonlinearities of structural dynamic characteristics and aeroelastic forces caused by large deformation are fully considered. An interesting resuh obtained was that the bridge was more stable when the stiffening girders were erected in a non-symmetrical manner as opposed to the traditional symmetrical erection schedule. It was also found that the severe decrease in the aerodynamic stability was due to the nonlinear effects. Therefore, the nonlinear factors should be considered accurately in aerodynamic stability analysis of long-span suspension bridges during erection.

  7. Recent Research and Applications of Numerical Simulation for Dynamic Response of Long-Span Bridges Subjected to Multiple Loads

    OpenAIRE

    Zhiwei Chen; Bo Chen

    2014-01-01

    Many long-span bridges have been built throughout the world in recent years but they are often subject to multiple types of dynamic loads, especially those located in wind-prone regions and carrying both trains and road vehicles. To ensure the safety and functionality of these bridges, dynamic responses of long-span bridges are often required for bridge assessment. Given that there are several limitations for the assessment based on field measurement of dynamic responses, a promising approach...

  8. Aerodynamic problems of cable-stayed bridges spanning over one thousand meters

    Institute of Scientific and Technical Information of China (English)

    Chen Airong; Ma Rujin; Wang Dalei

    2009-01-01

    Tbe elongating of cable-stayed bridge brings a series of aerodynamic problems. First of all, geometric nonlin-ear effect of extreme long cable is much more significant for cable-stayed bridge spanning over one thousand meters. Lat-eral static wind load will generate additional displacement of long cables, which causes the decrease of supporting rigidi-ty of the whole bridge and the change of dynamic properties. Wind load, being the controlling load in the design of ca-hie-stayed bridge, is a critical problem and needs to be solved. Meanwhile, research on suitable system between pylon and deck indicates fixed-fixed connection system is an effective way for improvement performance of cable-stayed bridges under longitudinal wind load. In order to obtain aerodynamic parameters of cable-stayed bridge spanning over one thou-sand meters, identification method for flutter derivatives of full bridge aero-elastic model is developed in this paper. Furthermore, vortex induced vibration and Reynolds number effect are detailed discussed.

  9. Deployment of a Smart Structural Health Monitoring System for Long-Span Arch Bridges: A Review and a Case Study.

    Science.gov (United States)

    Chen, Zengshun; Zhou, Xiao; Wang, Xu; Dong, Lili; Qian, Yuanhao

    2017-09-19

    Structural health monitoring (SHM) technology for surveillance and evaluation of existing and newly built long-span bridges has been widely developed, and the significance of the technique has been recognized by many administrative authorities. The paper reviews the recent progress of the SHM technology that has been applied to long-span bridges. The deployment of a SHM system is introduced. Subsequently, the data analysis and condition assessment including techniques on modal identification, methods on signal processing, and damage identification were reviewed and summarized. A case study about a SHM system of a long-span arch bridge (the Jiubao bridge in China) was systematically incorporated in each part to advance our understanding of deployment and investigation of a SHM system for long-span arch bridges. The applications of SHM systems of long-span arch bridge were also introduced. From the illustrations, the challenges and future trends for development a SHM system were concluded.

  10. A Summary Review of Correlations between Temperatures and Vibration Properties of Long-Span Bridges

    Directory of Open Access Journals (Sweden)

    Guang-Dong Zhou

    2014-01-01

    Full Text Available The shift of modal parameters induced by temperature fluctuation may mask the changes of vibration properties caused by structural damage and result in false structural condition identification. Thoroughly understanding the temperature effects on vibration properties of long-span bridges becomes an especially important issue before vibration-based damage detection methodologies are applied in real bridges. This paper presents an overview of current research activities and developments in the field of correlations between temperatures and vibration properties of long-span bridges. The theoretical derivation methods using classical structural dynamics and closed-form formulations are first briefly introduced. Then the trend analysis methods that are intended to extract the degree of variability in vibration property under temperature variation for different bridges by numerical analysis, laboratory test, or field monitoring are reviewed in detail. Following that, the development of quantitative models to quantify the temperature influence on vibration properties is discussed including the linear model, nonlinear model, and learning model. Finally, some promising research efforts for promoting the study of correlations between temperatures and vibration properties of long-span bridges are suggested.

  11. The Response of Long-Span Bridges to Low Frequency, Near-Fault Earthquake Ground Motions

    Energy Technology Data Exchange (ETDEWEB)

    McCallen, David; Astaneh-Asl, A.; Larsen, S.C.; Hutchings, Larry

    2009-02-27

    Historical seismic hazard characterizations did not include earthquake ground motion waveforms at frequencies below approximately 0.2 Hz (5 seconds period). This resulted from limitations in early strong motion instrumentation and signal processing techniques, a lack of measurements in the near-field of major earthquakes and therefore no observational awareness, and a delayed understanding in the engineering community of the potential significance of these types of motions. In recent years, there is a growing recognition of the relevance of near-fault, low frequency motions, particularly for long-period structures such as large bridges. This paper describes a computationally based study of the effects of low frequency (long-period) near-fault motions on long-span bridge response. The importance of inclusion of these types of motions for long span cable supported bridges is demonstrated using actual measured broad-band, near-fault motions from large earthquakes.

  12. Stability Analysis of Long-Span Continuous Rigid Frame Bridge with Thin-Wall Pier

    Institute of Scientific and Technical Information of China (English)

    HE Bo; SHI Ya-nan; ZHU Hong-ping; GUO Wen-zeng; CHEN Yong

    2008-01-01

    During cantilever cast in construction of high-pier and large-span continuous rigid frame bridges, structural stability in the longest cantilevered stage is very important. Based on a practical design case of a large-span continuous rigid frame bridge in Wuhan, the longest span stability coefficient is calculated with linear-buckling and nonlinear-buckling methods, respectively. The influences of both geometrical nonlinearity and the dual nonlinearity of material and geometry are considered. Numerical results indicate that the nonlinear solution is necessary to stability analysis because linear buckling loads axe much higher than those of nonlinear buckling. Thus, the edge fiber yield criterion is more convenient and faster than ultimate loading criterion when estimating nonlinear stability of structure, and can be used easily in the initial engineering design.

  13. Structure-borne low-frequency noise from multi-span bridges: A prediction method and spatial distribution

    Science.gov (United States)

    Song, X. D.; Wu, D. J.; Li, Q.; Botteldooren, D.

    2016-04-01

    Structure-borne noise from railway bridges at far-field points is an important indicator in environmental noise assessment. However, studies that predict structure-borne noise tend to model only single-span bridges, thus ignoring the sound pressure radiating from adjacent spans. To simulate the noise radiating from multi-span bridges induced by moving vehicles, the vibrations of a multi-span bridge are first obtained from a three-dimensional (3D) vehicle-track-bridge dynamic interaction simulation using the mode superposition method. A procedure based on the 2.5-dimensional (2.5D) boundary element method (BEM) is then presented to promote the efficiency of acoustical computation compared with the 3D BEM. The simulated results obtained from both the single-span and multi-span bridge models are compared with the measured results. The sound predictions calculated from the single-span model are accurate only for a minority of near-field points. In contrast, the sound pressures calculated from the multi-span bridge model match the measured results in both the time and frequency domains for all of the near-field and far-field points. The number of bridge spans required in the noise simulation is then recommended related to the distance between the track center and the field points of interest. The spatial distribution of multi-span structure-borne noise is also studied. The variation in sound pressure levels is insignificant along the length of the bridge, which validates the finding that the sound test section can be selected at an arbitrary plane perpendicular to the multi-span bridge.

  14. Instrumentation for durability monitoring of a long-span cable-stayed bridge

    Science.gov (United States)

    Hua, X. G.; Ni, Y. Q.; Zhou, H. F.; Ko, J. M.

    2005-05-01

    This paper outlines the design of an instrumentation system for durability monitoring of the world's longest cable-stayed bridge: the Sutong Bridge with a central span of 1088 m. As part of the Structural Health Monitoring And Safety Evaluation System (SHMASES) for the Sutong Bridge, the durability monitoring system is designed to monitor the corrosion in reinforced concrete structures. The sensors for durability monitoring include two categories. The first category refers to the sensors to monitor the causes leading to corrosion, such as temperature and relative humidity. The second category is electrode assemblies which are used to monitor the end results of corrosion. Data from the sensory system are then periodically collected using a portable or remotely computerized data acquisition system. The collected data from this system will provide useful information on maintenance and repair of concrete structures, and are envisaged to be incorporated into the reliability-based safety evaluation system developed for the Sutong Bridge

  15. Recent Research and Applications of Numerical Simulation for Dynamic Response of Long-Span Bridges Subjected to Multiple Loads

    Directory of Open Access Journals (Sweden)

    Zhiwei Chen

    2014-01-01

    Full Text Available Many long-span bridges have been built throughout the world in recent years but they are often subject to multiple types of dynamic loads, especially those located in wind-prone regions and carrying both trains and road vehicles. To ensure the safety and functionality of these bridges, dynamic responses of long-span bridges are often required for bridge assessment. Given that there are several limitations for the assessment based on field measurement of dynamic responses, a promising approach is based on numerical simulation technologies. This paper provides a detailed review of key issues involved in dynamic response analysis of long-span multiload bridges based on numerical simulation technologies, including dynamic interactions between running trains and bridge, between running road vehicles and bridge, and between wind and bridge, and in the wind-vehicle-bridge coupled system. Then a comprehensive review is conducted for engineering applications of newly developed numerical simulation technologies to safety assessment of long-span bridges, such as assessment of fatigue damage and assessment under extreme events. Finally, the existing problems and promising research efforts for the numerical simulation technologies and their applications to assessment of long-span multiload bridges are explored.

  16. Recent research and applications of numerical simulation for dynamic response of long-span bridges subjected to multiple loads.

    Science.gov (United States)

    Chen, Zhiwei; Chen, Bo

    2014-01-01

    Many long-span bridges have been built throughout the world in recent years but they are often subject to multiple types of dynamic loads, especially those located in wind-prone regions and carrying both trains and road vehicles. To ensure the safety and functionality of these bridges, dynamic responses of long-span bridges are often required for bridge assessment. Given that there are several limitations for the assessment based on field measurement of dynamic responses, a promising approach is based on numerical simulation technologies. This paper provides a detailed review of key issues involved in dynamic response analysis of long-span multiload bridges based on numerical simulation technologies, including dynamic interactions between running trains and bridge, between running road vehicles and bridge, and between wind and bridge, and in the wind-vehicle-bridge coupled system. Then a comprehensive review is conducted for engineering applications of newly developed numerical simulation technologies to safety assessment of long-span bridges, such as assessment of fatigue damage and assessment under extreme events. Finally, the existing problems and promising research efforts for the numerical simulation technologies and their applications to assessment of long-span multiload bridges are explored.

  17. Newly developed high performance structural steels for long span bridge construction; Chotaikyo ni shiyosareru shinkozai

    Energy Technology Data Exchange (ETDEWEB)

    Tomita, Y. [Nippon Steel Corp., Tokyo (Japan)

    1998-11-15

    This paper reports new steels for long span bridge construction with the thick steel plate as a main part. On the basis of the high-tension steel utilizing technology examined around 1965, a reheated, quenched-and-tempered martensitic steel plate (HT690) was used for the Onaruto Bridge and Seto Ohashi Bridge in a Honsyu-Shikoku linking project. Moreover, a larger number of quenched martensitic high-tension steel plates (HT670 and HT780) were used for the Yojima Bridge together with existing SM400, SM490, SM520, and SM570 steel plates. The lately built Akashi Kaikyo Ohashi Bridge that is 1990 m between struts is longest in the world. The newly developed steel plate (HT780) for a bridge girder of which weldability was improved for lightening was used actually. To reduce the welding cost or improve the welding environment, this steel plate decreased the preheating temperature for weld cracking prevention in a heat-affected zone from about 100degC to 50degC or less. A new wire (of 1800Mpa in tensile strength) was also used for a cable. In future, the bridge girder will be economically and rationally manufactured by the development of design and construction methods that fully draw the characteristics of the new steel. 33 refs., 9 figs., 2 tabs.

  18. Thermal correlation analysis of a long-span suspension bridge static responses

    Science.gov (United States)

    Zhou, Linren; Chen, Lan; Xia, Yong; Brownjohn, James M. W.

    2016-04-01

    Harsh service environment degenerates the performance of bridges even leads to catastrophic collapse. Structural temperature has been widely recognized as one of the most negative environmental effects on bridges. The structural responses are deeply affected by the variation and distribution of temperatures on bridges. Therefore, identifying the correlations between them is a significant issue for structural safety assessment. In this study, the relationships between the temperature induced static response and the surrounding weather factors are investigated based on the long-term field measurements of a long-span suspension bridge. The correlations of the meteorological parameters between the bridge filed and the nearby weather station, and the relations of structural static responses to the air temperature, are investigated. The results indicate that relationships of meteorological parameters between nearby weather station and the bridge field can be predicted. The correlation between the static responses and the air temperature and is remarkable with high correlation coefficient. The conclusions are expected to provide reference for the design and evaluation of longspan suspension bridges.

  19. Damage alarming of long-span suspension bridge based on GPS-RTK monitoring

    Institute of Scientific and Technical Information of China (English)

    缪长青; 王蔓; 田洪金; 冯兆祥; 陈策

    2015-01-01

    Structure damage identification and alarming of long-span bridge were conducted with three-dimensional dynamic displacement data collected by GPS subsystem of health monitoring system on Runyang Suspension Bridge. First, the effects of temperature on the main girder spatial position coordinates were analyzed from the transverse, longitudinal and vertical directions of bridge, and the correlation regression models were built between temperature and the position coordinates of main girder in the longitudinal and vertical directions; then the alarming indices of coordinate residuals were conducted, and the mean-value control chart was applied to making statistical pattern identification for abnormal changes of girder dynamic coordinates; and finally, the structural damage alarming method of main girder was established. Analysis results show that temperature has remarkable correlation with position coordinates in the longitudinal and vertical directions of bridge, and has weak correlation with the transverse coordinates. The 3% abnormal change of the longitudinal coordinates and 5% abnormal change of the vertical ones caused by structural damage are respectively identified by the mean-value control chart method based on GPS dynamic monitoring data and hence the structural abnormalities state identification and damage alarming for main girder of long-span suspension bridge can be realized in multiple directions.

  20. Epoxy asphalt concrete paving on the deck of long-span steel bridges

    Institute of Scientific and Technical Information of China (English)

    HUANG Wei; QIAN Zhendong; CHEN Gang; YANG Jun

    2003-01-01

    It is the first systematic research in the world on the composition design of epoxy asphalt concrete as pav- ing material. Material characteristics and service perform- ance of mixture, fatigue resistance characteristics of epoxy asphalt concrete by the fatigue test of complex beam have also been described. This research indicates that epoxy asphalt concrete is a good type of paving material. Research results have been applied successfully in the paving of steel deck of the Second Nanjing Yangtze River Bridge (SNYRB). It provides a new paving type for long-span steel bridges of China and has a bright application prospect.

  1. Seismic spatial effects on long-span bridge response in nonstationary inhomogeneous random fields

    Science.gov (United States)

    Jiahao, Lin; Yahui, Zhang; Yan, Zhao

    2005-06-01

    The long-span bridge response to nonstationary multiple seismic random excitations is investigated using the PEM (pseudo excitation method). This method transforms the nonstationary random response analysis into ordinary direct dynamic analysis, and therefore, the analysis can be solved conveniently using the Newmark, Wilson-θ schemes or the precise integration method. Numerical results of the seismic response for an actual long-span bridge using the proposed PEM are given and compared with the results based on the conventional stationary analysis. From the numerical comparisons, it was found that both the seismic spatial effect and the nonstationary effect are quite important, and that both stationary and nonstationary seismic analysis should pay special attention to the wave passage effect.

  2. Seismic spatial effects on long-span bridge response in nonstationary inhomogeneous random fields

    Institute of Scientific and Technical Information of China (English)

    Lin Jiahao; Zhang Yahui; Zhao Yan

    2005-01-01

    The long-span bridge response to nonstationary multiple seismic random excitations is investigated using the PEM (pseudo excitation method). This method transforms the nonstationary random response analysis into ordinary direct dynamic analysis, and therefore, the analysis can be solved conveniently using the Newmark, Wilson-θ schemes or the precise integration method. Numerical results of the seismic response for an actual long-span bridge using the proposed PEM are given and compared with the results based on the conventional stationary analysis. From the numerical comparisons, it was found that both the seismic spatial effect and the nonstationary effect are quite important, and that both stationary and nonstationary seismic analysis should pay special attention to the wave passage effect.

  3. Optical measurement system applied to continuous displacement monitoring of long-span suspension bridges

    Science.gov (United States)

    Lages Martins, L.; Rebordão, J. M.; Ribeiro, A. S.

    2013-04-01

    This paper provides a general description of main issues related to the design of an optical measurement system applied to continuous displacement monitoring of long-span suspension bridges. The proposed system's architecture is presented and its main components - camera and active targets - are described in terms of geometrical and radiometric characteristics required for long distance measurement of the tridimensional displacement of the stiffness girder in the middle section of the bridge's central span. The intrinsic and extrinsic camera parameterization processes, which support the adopted measurement approach, are explained in a specific section. Since the designed measurement system is intended to perform continuous displacement monitoring in long distance observation framework, particular attention is given to environmental effects, namely, refraction, turbulence and sensor saturation phenomena, which can influence the displacement measurement accuracy. Finally, a measurement uncertainty method is discussed in order to provide a suitable solution for the determination of the accuracy related to the proposed measurement approach.

  4. Dynamic Response of the Suspension Spans of the San Francisco-Oakland Bay Bridge

    Energy Technology Data Exchange (ETDEWEB)

    McCallen, D; Astaneh-Asl, A; Larsen, S; Hutchings, L

    2005-11-03

    The dynamic response of the suspension spans of the San Francisco-Oakland Bay Bridge (SFOBB) have been numerically modeled in a case-study to investigate the effects of long-period, near-field ground motions on flexible suspension bridges. The structural simulation model used in the study was developed as a special purpose computer program tailored to efficiently simulate the nonlinear response of cable supported bridges. The simulation model includes a number of special element technologies and solution algorithms that enable efficient nonlinear analysis of suspension bridges. The ground motions used in the study were site specific synthetic records for a Mw=7.25 earthquake along the Hayward fault at 12-15 km distant, and actual measured near-field records from the Izmit Turkey (1999) and Chi-Chi Taiwan (1999) earthquakes. These records include near- and far-field broad-band motions for three components. The results of the numerical simulations indicate that low frequency waveforms associated with near-field motions can place a significant demand on the structural systems of suspension bridges, and must be accounted for in suspension bridge analysis and design.

  5. Application of AN Automated Wireless Structural Monitoring System for Long-Span Suspension Bridges

    Science.gov (United States)

    Kurata, M.; Lynch, J. P.; van der Linden, G. W.; Hipley, P.; Sheng, L.-H.

    2011-06-01

    This paper describes an automated wireless structural monitoring system installed at the New Carquinez Bridge (NCB). The designed system utilizes a dense network of wireless sensors installed in the bridge but remotely controlled by a hierarchically designed cyber-environment. The early efforts have included performance verification of a dense network of wireless sensors installed on the bridge and the establishment of a cellular gateway to the system for remote access from the internet. Acceleration of the main bridge span was the primary focus of the initial field deployment of the wireless monitoring system. An additional focus of the study is on ensuring wireless sensors can survive for long periods without human intervention. Toward this end, the life-expectancy of the wireless sensors has been enhanced by embedding efficient power management schemes in the sensors while integrating solar panels for power harvesting. The dynamic characteristics of the NCB under daily traffic and wind loads were extracted from the vibration response of the bridge deck and towers. These results have been compared to a high-fidelity finite element model of the bridge.

  6. Field Testing and Load Rating of a Short-Span Thermoplastic Bridge System, Bridge T-8519

    Science.gov (United States)

    2010-11-01

    defined as elastoplastic , meaning it had primarily elastic behavior com- bined with time-dependent fluid properties as well. Allowable stress and...degradation or damage must be considered in future load ratings. ERDC/GSL TR-10-48 38 References AASHTO. 2003. Manual for the condition evaluation... damage or deterioration. Often, bridges are rated poorly because of inaccurate representations of the structural geometry or because the material and/or

  7. Seismic performance evaluation of multi-span existing masonry arch bridge

    Science.gov (United States)

    Laterza, Michelangelo; D'Amato, Michele; Casamassima, Vito Michele

    2017-07-01

    Existing old masonry arch bridges represent an architectural and cultural heritage of inestimable value, assuming nowadays an important strategic role since most of them are still in service and link roads of primary importance for vehicular traffic. They were mostly built in the last century without considering any horizontal action, and nowadays are serving roads characterized by a transit loads certainly heavier and more frequent than the ones of past. Moreover, very often due to absence of maintenance and to weathering conditions, the elements deteriorate more and more with a consequent loss of integrity and reduction of their carrying capacity. In this paper the seismic assessment of an old multi span masonry arch bridge still in service is illustrated. Pushover analyses are performed with the aim to investigate the numerical model sensitivity and the influence on the global nonlinear response of the bridge components.

  8. Research on Hybrid Seismic Response Control System for Motion Control of Two Span Bridge

    Science.gov (United States)

    Heo, G.; Kim, C.; Jeon, S.; Seo, S.; Jeon, J.

    2016-09-01

    In this paper, a hybrid seismic response control (HSRC) system was developed to control bridge motion caused by seismic load. It was aimed at optimum vibration control, composed of a rubber bearing of passive type and a MR-damper of semi-active type. The bridge model was built for experiment, a two-span bridge of 8.3 meters in length with the HSRC system put up on it. Then, inflicting El-centro seismic load on it, shaking table tests were carried out to confirm the system's validity. The experiments were conducted under the basic structure state (without an MR-damper applied) first, and then under the state with an MR-damper applied. It was also done under the basic structure state with a reinforced rubber bearing applied, then the passive on/off state of the HSRC system, and finally the semi-active state where the control algorithm was applied to the system. From the experiments, it was observed that collision rather increased when the MR-damper alone was applied, and also that the application of the HSRC system effectively prevented it from occurring. As a result, the HSRC system was proven to be effective in mitigating responses of the two-span bridge under seismic load.

  9. Dynamic Strain Sensing in a Long-Span Suspension Bridge Using Fiber Bragg Grating Sensors

    Science.gov (United States)

    Zhu, Yinian; Zhu, Yan-Jin; Balogun, Oluwaseyi; Zhu, Songye; Xu, You-Lin; Krishnaswamy, Sridhar

    2011-06-01

    Optical fiber sensors are ideal for monitoring continuous deterioration conditions of civil infrastructure, especially of long-span bridges. Typically, a network of sensors is used to measure the strains or low frequency vibrational response of the structure. In this work, we demonstrate dynamic spectral demodulation of fiber Bragg grating (FBG) sensor responses with a stabilized Michelson interferometer for monitoring mechanical strains in a model of long-span bridge. A series of experiments has been performed, including the measurements of the natural resonant modes of the model bridge, impact response of a bridge member and acoustic emissions in a fractured aluminum bar. The experimental results not only reveal that dynamic spectral demodulation of FBG strain responses at frequencies extending up to about 3.5 MHz is possible, but also suggest that the method may be suitable for monitoring high frequency mechanical strains in civil structures that result from cracking or impact loading, thus providing a tool for local detection of structural damage.

  10. Buffeting response of long-span cable-supported bridges under skew winds. Part 1: theory

    Science.gov (United States)

    Zhu, L. D.; Xu, Y. L.

    2005-03-01

    A finite-element-based framework for buffeting analysis of long-span cable-supported bridges under skew winds is developed in the frequency domain utilizing the linear quasi-steady theory and the strip theory of aerodynamics in conjunction with the pseudo excitation method. A set of universal expressions for six components of buffeting forces is first derived in association with oblique cross-sections of bridge components, in which the buffeting forces are formed with respect to the wind coordinate system and then converted to those with respect to the structural coordinate system. Skew mean wind and three orthogonal components of velocity fluctuations can thus be easily handled without any further decomposition. The coherence between velocity fluctuations of wind turbulence at any two arbitrary spatial points is considered in the global wind coordinate system rather than in the global structural coordinate system. Aeroelastic stiffness and damping matrices due to self-excited forces are then taken into consideration in terms of the 18 flutter derivatives with respect to the oblique cross-sections. The pseudo-excitation method is finally employed to solve efficiently the fully coupled 3D buffeting problem of long-span cable-supported bridges under skew winds with the effects of multi-modes and spatial modes, inter-mode coupling and aerodynamic coupling, and the interaction among major bridge components being naturally included.

  11. Online automatic identification of the modal parameters of a long span arch bridge

    Science.gov (United States)

    Magalhães, Filipe; Cunha, Álvaro; Caetano, Elsa

    2009-02-01

    The "Infante D. Henrique" bridge is a concrete arch bridge, with a span of 280 m that crosses the Douro River, linking the cities of Porto and Gaia located in the North of Portugal. This structure is being monitored by a recently installed dynamic monitoring system that comprises 12 acceleration channels. This paper describes the bridge structure, its dynamic parameters identified with a previously developed ambient vibration test, the installed monitoring equipment and the software that continuously processes the data received from the bridge through an Internet connection. Special emphasis is given to the algorithms that have been developed and implemented to perform the online automatic identification of the structure modal parameters from its measured responses during normal operation. The proposed methodology uses the covariance driven stochastic subspace identification method (SSI-COV), which is then complemented by a new algorithm developed for the automatic analysis of stabilization diagrams. This new tool, based on a hierarchical clustering algorithm, proved to be very efficient on the identification of the bridge first 12 modes. The results achieved during 2 months of observation, which involved the analysis of more than 2500 datasets, are presented in detail. It is demonstrated that with the combination of high-quality equipment and powerful identification algorithms, it is possible to estimate, in an automatic manner, accurate modal parameters for several modes. These can then be used as inputs for damage detection algorithms.

  12. Study on Fatigue Behavior of Anchorage of Cable and Girder of Long Span Cable-Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    A full scale model test is done and a FEM model is established toinvestigate the fatigue behavior of the Nancha cable-stayed bridge of the Nanjing Second Yangtz River Bridge, a long span steel bridge with a main span of 628 m. The results of test and FEM are analyzed and compared. It is shown that they are in good agreement. It is verified that the fatigue characteristic of the anchorage structure of cable and girder of the bridge satisfies the requirements specified by Chinese, British and American codes.

  13. Simple Evaluation of Load-Carrying Capacity of Multi-Span Folding Bridges based on Floating Supports

    Directory of Open Access Journals (Sweden)

    Jan Marszałek

    2014-12-01

    Full Text Available [b]Abstract[/b]. The papers covers simple evaluation of load-carrying capacity of multi-span folding bridges based on floating supports. Combined bridges built in this approach, could be used as a temporary crossing. The methodology of this evaluation is shown graphically on the basis of designed nomograms for two existing bridge structures i.e. MS-54 and DMS-65, mounted on rigid and floating supports. These nomograms facilitate the simple and fast determination of the impact of changing fixed support into floating support with different bridge length spans on the carrying capacity of the bridge. The paper also presents the influence of long-term use (enlarging the mounting backlash in the joints of these structures on the carrying capacity of the bridge.[b]Keywords[/b]: building, folding bridges, nomograms, assembly clearances

  14. Dimensional field testing of an optical measurement system in a long-span suspension bridge

    Science.gov (United States)

    Lages Martins, Luis F.; Rebordão, José Manuel; Ribeiro, Álvaro S.

    2015-05-01

    The dimensional field testing activity described in this paper allowed measuring the vertical and transverse dynamic displacement related to the main span (with a dimension equal to 1012 meters) central section of a long-span suspension bridge - the 25th of April Bridge (P25A), in Lisbon (Portugal) - using an optical system composed by high focal length lens (600 mm), digital image sensor and active infrared LED targets. Maximum values of 0,53 m and 0,29 m were obtained for the vertical and transverse displacements without rail traffic on the P25A. Passenger train circulation on the bridge's lower rail deck increased the vertical displacement up to 1,69 m. The applied measuring system was subjected to an in situ calibration procedure (SI traceable), showing maximum deviations close to 1,3 mm with an expanded measurement uncertainty (in a 95% confidence interval) around 3,0 mm, in a favorable observation scenario (winter season with low vertical thermal gradient in the atmosphere). Field studies of optical phenomena such as atmospheric refraction and beam wandering effect by turbulence were also performed, aiming the validation of developed refraction correction models and the quantification of targets image coordinates dispersions (0,13 pixel in winter season a 0,56 pixel during summer season).

  15. Structural condition assessment of long-span suspension bridges using long-term monitoring data

    Science.gov (United States)

    Yang, Deng; Youliang, Ding; Aiqun, Li

    2010-03-01

    This paper focuses on developing an online structural condition assessment technique using long-term monitoring data measured by a structural health monitoring system. The seasonal correlations of frequency-temperature and beam-end displacement-temperature for the Runyang Suspension Bridge are performed, first. Then, a statistical modeling technique using a six-order polynomial is further applied to formulate the correlations of frequency-temperature and displacement-temperature, from which abnormal changes of measured frequencies and displacements are detected using the mean value control chart. Analysis results show that modal frequencies of higher vibration modes and displacements have remarkable seasonal correlations with the environmental temperature and the proposed method exhibits a good capability for detecting the micro damage-induced changes of modal frequencies and displacements. The results demonstrate that the proposed method can effectively eliminate temperature complications from frequency and displacement time series and is well suited for online condition monitoring of long-span suspension bridges.

  16. Damage identification of a large-span concrete cable-stayed bridge based on genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    ZHU Jinsong; XIAO Rucheng

    2007-01-01

    The global stability of a structure, the stiffness of its main girder and concrete tower, and the variation of the forces of its stay cables are key issues to the safety assessment of an in-service cable-stayed bridge. The efficiency and ratio- nality of local elaborate non-damage-identification could be enhanced by the primary damage identification of cable- stayed bridges on the basis of periodic detection of the cable force and strain monitor in key sections of the main girder. The genetic algorithms of damage identification for cable- stayed bridges were investigated in this paper on the basis of the monitor data of the cable force and strain in a key section of the main girder. A damage detection program for complex civil structure was generated to implement the identification of damage location and extent. The deterioration of the struc- ture was calculated according to the variation of monitor data. It is demonstrated that the results of damage identification from the parametric finite element method are accurate. The method had been verified using a long-span concrete cable- stayed bridge in Ningbo, which has been in use for the past four years.

  17. A Combined Geophysical/Engineering Approach for the Seismic Safety of Long-Span Bridges

    Science.gov (United States)

    Fäcke, Andreas; Stempniewski, Lothar; Richwalski, Sandra M.; Parolai, Stefano; Milkereit, Claus; Wang, Rongjiang; Bormann, Peter; Roth, Frank

    The spatial distribution of the resonance frequency of the sedimentary cover in the Cologne area was estimated by the horizontal-to-vertical spectral ratio method using ambient noise measurements. A comparison with the eigenfrequencies of selected long-span bridges crossing the Rhine river indicated an overlap in frequency and therefore potential damage in the case of an earthquake. Consequently, we conducted a dynamic vulnerability analysis using the finite-element method. In addition to accelerograms from design spectra, ground motion scenarios with sources located on the most proximate fault (Erft fault) were simulated using a numerical hybrid method that takes into account source, path, and site effects. The results indicated that due to the low frequency content of these scenarios, consistently higher responses - compared to the recommended loads in the German seismic code - were obtained at all selected bridges. Usage of both scenarios revealed specific failure mechanisms. While cable supported bridges seem to be secure, grave failure was detected for a box girder bridge.

  18. Accurate stress analysis on rigid central buckle of Ions-span suspension bridges based on submodel method

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; LI AiQun; GUO Tong; MA Shuang

    2009-01-01

    Runyang Suspension Bridge (RSB) with the main span of 1490 m is the longest bridge in China and the third longest one in the world. In this bridge the rigid central buckle is employed for the first time in the mid-span of the suspension bridge in China. For such a super-long-span bridge, the traditional finite element (FE) modeling technique and stress analysis methods obviously cannot satisfy the needs of conducting accurate stress analysis on the central buckle. In this paper, the submodel method is introduced and for the first time used in analyzing the stresses of the central buckle. After an accurate FE submodel of the central buckle was specially established according to the analysis results from the whole FE model, the connection technique between the two-scale FE models was realized and the accurate stresses of the central buckle under various vehicle load cases were then conducted based on the submodel method. The calculation results were testified to be accurate and reliable by the field measurements, which show the efficiency and reliability of the submodel method on analyzing the mechanical condition of the central buckle of long-span suspension bridges. Finally, the working behavior and mechanical characteristics of the central buckle of the RSB under vehicle loads were analyzed based on the calculation and measurement results. The results obtained in this paper can provide theoretic references for analyzing and designing the rigid central buckle in long-span suspension bridges in future.

  19. Accurate stress analysis on rigid central buckle of long-span suspension bridges based on submodel method

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Runyang Suspension Bridge (RSB) with the main span of 1490 m is the longest bridge in China and the third longest one in the world. In this bridge the rigid central buckle is employed for the first time in the mid-span of the suspension bridge in China. For such a super-long-span bridge, the traditional finite element (FE) modeling technique and stress analysis methods obviously cannot satisfy the needs of conducting accurate stress analysis on the central buckle. In this paper, the submodel method is in- troduced and for the first time used in analyzing the stresses of the central buckle. After an accurate FE submodel of the central buckle was specially established according to the analysis results from the whole FE model, the connection technique between the two-scale FE models was realized and the ac- curate stresses of the central buckle under various vehicle load cases were then conducted based on the submodel method. The calculation results were testified to be accurate and reliable by the field measurements, which show the efficiency and reliability of the submodel method on analyzing the mechanical condition of the central buckle of long-span suspension bridges. Finally, the working be- havior and mechanical characteristics of the central buckle of the RSB under vehicle loads were ana- lyzed based on the calculation and measurement results. The results obtained in this paper can provide theoretic references for analyzing and designing the rigid central buckle in long-span suspension bridges in future.

  20. Minimum depth of soil cover above long-span soil-steel railway bridges

    Science.gov (United States)

    Esmaeili, Morteza; Zakeri, Jabbar Ali; Abdulrazagh, Parisa Haji

    2013-12-01

    Recently, soil-steel bridges have become more commonly used as railway-highway crossings because of their economical advantages and short construction period compared with traditional bridges. The currently developed formula for determining the minimum depth of covers by existing codes is typically based on vehicle loads and non-stiffened panels and takes into consideration the geometrical shape of the metal structure to avoid the failure of soil cover above a soil-steel bridge. The effects of spans larger than 8 m or more stiffened panels due to railway loads that maintain a safe railway track have not been accounted for in the minimum cover formulas and are the subject of this paper. For this study, two-dimensional finite element (FE) analyses of four low-profile arches and four box culverts with spans larger than 8 m were performed to develop new patterns for the minimum depth of soil cover by considering the serviceability criterion of the railway track. Using the least-squares method, new formulas were then developed for low-profile arches and box culverts and were compared with Canadian Highway Bridge Design Code formulas. Finally, a series of three-dimensional (3D) finite element FE analyses were carried out to control the out-of-plane buckling in the steel plates due to the 3D pattern of train loads. The results show that the out-of-plane bending does not control the buckling behavior of the steel plates, so the proposed equations for minimum depth of cover can be appropriately used for practical purposes.

  1. Life-Cycle Monitoring of Long-Span PSC Box Girder Bridges through Distributed Sensor Network: Strategies, Methods, and Applications

    Directory of Open Access Journals (Sweden)

    Zheheng Chen

    2015-01-01

    Full Text Available Structural health monitoring (SHM has attracted much attention in recent years, which enables early warnings of structural failure, condition assessments, and rational maintenance/repair strategies. In the context of bridges, many long-span steel bridges in China have been installed with the SHM systems; however, the applications of the SHM in prestressed concrete (PSC bridges are still rather limited. On the other hand, the PSC box girder bridges are extensively used in highway and railway systems and premature damage of these bridges is often reported, resulting in considerable maintenance and/or replacement costs. First, this paper presents a state-of-art review on the SHM of long-span PSC bridges. Monitoring strategies, methods, and previous applications for these bridges are summarized and discussed. In order to well capture the behavior of the bridge during its whole life and to maximize the use of sensors, a life-cycle monitoring strategy is proposed, in which the sensor layout is determined according to requirements for construction monitoring, completion test, and in-service monitoring. A case study is made on a three-span PSC box girder bridge in China. The system configuration, sensor layout, and data communications, and so forth, are presented. The up-to-date monitored structural responses are analyzed and compared with the design values.

  2. Aseismic structure of the foundations of super long span bridges; Cho chodai kyoryo no kiso ni motomerareru taishin kozo

    Energy Technology Data Exchange (ETDEWEB)

    Yamagata, M. [Honshu Shikoku Bridge Authority, Kobe (Japan); Tanaka, T. [Oriental Consultants Co. Ltd., Tokyo (Japan)

    1995-09-20

    All the long span bridges that are planned across the straits on the second national expressway, are essential foundations on the deep sea bottom or on the bedrock overlaid with deep sediments, moreover have longer spans than the Akashi Kaikyo Bridge, furthermore are under severe condition that superstructure reaction force is increased with the enlarged spans. Consequently, aseismic stability greatly influences the specifications of the foundations. Although, in a long span bridge foundation like this, it is possible to design and execute on subsequent of same type with Akashi Kaikyo Bridge which is going to execute now, it is evident that the cost of construction increases widely per unit length. In this paper, the concept of an aseismic structure for the foundations of super long span bridges based on the principle of earthquake countermeasures is described. In particular, authors have devised a new type of foundation for the deep sea, named as a `platform`, with a weight about half that of conventional one. The feasibility of this new foundation rests on the surveying, designing and construction technologies acquired from the Akashi Kaikyo Bridge project and on research and development extending over several years. 25 refs., 9 figs., 5 tabs.

  3. Towards actual brazilian traffic load models for short span highway bridges

    Directory of Open Access Journals (Sweden)

    C. E. Rossigali

    Full Text Available New live load models for highway bridge design in Brazil are under development by assembling real traffic database, traffic simulations, analytical-numerical modeling of the dynamic interaction between vehicle and structure and statistical extrapolations. This paper presents and discusses the results obtained in the first stages of this work which includes the comparison between the static effects due to the actual traffic of heavy vehicles and those generated by the live load model given in the current national code NBR 7188. It is demonstrated that this live load model is not appropriate to represent the actual traffic effects and may be, in some cases, non-conservative. The present work deals with short span bridges for two lanes single carriageway under free flow traffic scenarios. The representative static effects in these bridges due to the actual traffic of heavy vehicles are obtained by extrapolating its probability density functions to a certain return period. To this purpose, a traffic database was constructed by gathering data from several weighing stations in Brazilian highways which was then applied to perform traffic simulations through a specially developed computational tool.

  4. Buffeting response of long-span cable-supported bridges under skew winds. Part 2: case study

    Science.gov (United States)

    Xu, Y. L.; Zhu, L. D.

    2005-03-01

    The finite-element-based framework for buffeting analysis of long-span cable-supported bridges under skew winds has been presented in Part 1 of this paper. The framework is now applied to the Tsing Ma Suspension Bridge in Hong Kong as a case study. The wind velocities and bridge responses measured by the Wind and Structural Health Monitoring System (WASHMS) of the bridge during Typhoon Sam in 1999 are first analyzed to find the skew wind characteristics surrounding the bridge, the modal damping ratios and acceleration responses of the bridge. The buffeting responses of the bridge under skew winds during Typhoon Sam are then computed using the wind characteristics and modal damping ratios measured from the field and the aerodynamic coefficients and flutter derivatives of the bridge deck and tower measured from the wind tunnel under skew winds. The computed acceleration responses of the bridge deck and cable are finally compared with the responses measured from the field. The comparison is found to be satisfactory in general and the case study forms a good practical demonstration for the verification of the proposed method for buffeting analysis of long-span cable-supported bridges under skew winds.

  5. Geometry control of long-span continuous girder concrete bridge during construction through finite element model updating

    Science.gov (United States)

    Wu, Jie; Yan, Quan-sheng; Li, Jian; Hu, Min-yi

    2016-04-01

    In bridge construction, geometry control is critical to ensure that the final constructed bridge has the consistent shape as design. A common method is by predicting the deflections of the bridge during each construction phase through the associated finite element models. Therefore, the cambers of the bridge during different construction phases can be determined beforehand. These finite element models are mostly based on the design drawings and nominal material properties. However, the accuracy of these bridge models can be large due to significant uncertainties of the actual properties of the materials used in construction. Therefore, the predicted cambers may not be accurate to ensure agreement of bridge geometry with design, especially for long-span bridges. In this paper, an improved geometry control method is described, which incorporates finite element (FE) model updating during the construction process based on measured bridge deflections. A method based on the Kriging model and Latin hypercube sampling is proposed to perform the FE model updating due to its simplicity and efficiency. The proposed method has been applied to a long-span continuous girder concrete bridge during its construction. Results show that the method is effective in reducing construction error and ensuring the accuracy of the geometry of the final constructed bridge.

  6. 33 CFR 165.928 - Security Zone; Mackinac Bridge, Straits of Mackinac, Michigan.

    Science.gov (United States)

    2010-07-01

    ... waters of the United States means those waters defined as such in 33 CFR part 2. (4) Public vessel means...°43.731 W, which is the northwest corner; thence east to 45°50.705 N: 084°43.04 W, which is the... established in this section. Vessels with an operable Automatic Identification System (AIS) unit should...

  7. Influence of Excitation on Dynamic System Identification for a Multi-Span Reinforced Concrete Bridge

    Directory of Open Access Journals (Sweden)

    M. Alwash

    2009-01-01

    Full Text Available In vibration-based damage detection, changes to structural modal properties are tracked over time in order to infer the current state of damage or deterioration. As such, the ability to obtain reliable estimates of modal parameters, particularly natural frequencies and mode shapes, is of critical importance. In the present study, the influence of the dynamic excitation source on the accuracy and statistical uncertainty of modal property estimates for a three span reinforced concrete bridge was investigated experimentally and numerically. Comparisons were made between the dynamic responses due to vehicle loading, harmonic and random forcing, impact, and environmental excitation. It was demonstrated that natural frequencies and mode shapes extracted from the free vibration response following vehicle and random loading events were of higher quality than corresponding values determined during the forcing phase of those events. Harmonic excitation at resonant frequencies and impact were also found to produce statistically reliable results.

  8. Design and Construction of a 50m Single Span Ultra High Performance Ductile Concrete Composite Road Bridge

    Directory of Open Access Journals (Sweden)

    Voo - Yen Lei

    2012-04-01

    Full Text Available A single span 50m long prestressed road bridge was constructed under Public Works Department in the State of Negeri Sembilan, Malaysia contract recently. The bridge was constructed at a small village, Kampung Linsum, crossing a river, Sungai Linggi. To date, this bridge is the Malaysia first and may also be the world longest composite road bridge which made from ultra-high performance ductile concrete (UHPdC. This paper presents the feature of the UHPdC precast girder; brief in-sight of the manufacturing of the girder; the construction sequence of the bridge; the design method and lastly the environmental impact calculation. The midspan deflections of the bridge at different construction history were compared against the collected field data and it showed that the calculated values generally agree well with the field data.

  9. A smart model of a long-span suspended bridge for wind tunnel tests

    Science.gov (United States)

    Cinquemani, S.; Diana, G.; Fossati, L.; Ripamonti, F.

    2015-04-01

    Traditional aeroelastic models rely only on good mechanical design and accurate crafting in order to match the required structural properties. This paper proposes an active regulation of their structural parameters in order to improve accuracy and reliability of wind tunnel tests. Following the design process steps typical of a smart structure, a damping tuning technique allowing to control a specific set of vibration modes is developed and applied on the aeroelastic model of a long-span suspended bridge. Depending on the testing conditions, the structural damping value can be adjusted in a fast, precise and repeatable way in order to highlight the effects of the aerodynamic phenomena of interest. In particular, vortex-induced vibration are taken into consideration, and the response of a bridge section to vortex shedding is assessed. The active parameter regulation allows to widen the pattern of operating conditions in which the model can be tested. The paper discusses the choice of both sensors and actuators to be embedded in the structure and their positioning, as the control algorithm to obtain the desired damping. Experimental results are shown and results are discussed to evaluate the performance of the smart structure in wind dunnel tests.

  10. Control of wind-induced vibration of long-span bridges and tall buildings

    Institute of Scientific and Technical Information of China (English)

    GU Ming

    2007-01-01

    With the rapid increase in scales of structures,research on controlling wind-induced vibration of large-scale structures,such as long-span bridges and super-tall buildings,has been an issue of great concern.For wind-induced vibration of large-scale structures,vibration frequencies and damping modes vary with wind speed.Passive,semiactive,and active control strategies are developed to improve the windresistance performance of the structures in this paper.The multiple tuned mass damper (MTMD) system is applied to control vertical bending buffeting response.A new semiactive lever-type tuned mass damper (TMD) with an adjustable frequency is proposed to control vertical bending buffeting and torsional buffeting and flutter in the whole velocity range of bridge decks.A control strategy named sinusoidal reference strategy is developed for adaptive control of wind-induced vibration of super-tall buildings.Multiple degrees of freedom general building aeroelastic model with a square cross-section is tested in a wind tunnel.The results demonstrate that the proposed strategies can reduce vibration effectively,and can adapt to wind-induced vibration control of large-scale structures in the uncertain dynamic circumstance.

  11. Internet-based collaborative pseudo-dynamic testing of multi-span bridge structure

    Institute of Scientific and Technical Information of China (English)

    Dapeng Wang; Shizhu Tian; Xinjiang Cai; Yunlei Fan; Yan Xiao

    2009-01-01

    In this paper,the first Internet-based collaborative pseudo-dynamic testing of a multi-span bridge system in mainland China is presented in detail,which has been carried out by the collaboration of Hunan University (HNU),Harbin Institute of Technology (HIT) and Tsinghua University (TU) in mainland China,and the University of Southern California (USC) in the USA.The prototype system of Russion River Bridge at Southern California in America is illustrated.Different testing specimens,testing equipments and substructure boundary conditions at HNU and HIT laboratories are described.A network protocol platform for collaborative pseudo-dynamic testing,called NetSLab,and some function modules developed on the use of its standardized interface are introduced.Aiming at the MTS system widely used in structural testing,two approaches are presented to implement the communication interface between NetSLab and testing equipment,respectively,studied by HNU and HIT.The integrated networked testing system and collaborative testing procedures are presented.The testing results manifest that the networked collaborative testing system with powerful capability provides a testing platform with good coordination for complex models or actual structures,and achieves remote sharing of testing equipments.(C) 2009 National Natural Science Foundation of China and Chinese Academy of Sciences.Published by Elsevier Limited and Science inChina Press.All rights reserved.

  12. Implications of seismic pounding on the longitudinal response of multi-span bridges-an analytical perspective

    Institute of Scientific and Technical Information of China (English)

    Reginald DesRoches; Susendar Muthukumar

    2004-01-01

    Seismic pounding between adjacent frames in multiple-frame bridges and girder ends in multi-span simply supported bridges has been commonly observed in several recent earthquakes. The consequences of pounding include damage to piers, abutments, shear keys, bearings and restrainers, and possible collapse of deck spans. This paper investigates pounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developed including the effects of inelastic frame action and nonlinear hinge behavior, to study the seismic response to longitudinal ground motion. Pounding is implemented using the contact force-based Kelvin model, as well as the momentum-based stereomechanical approach, Parameter studies are conducted to determine the effects of frame period ratio, column hysteretic behavior, energy dissipation during impact and near source ground motions on the pounding response of the bridge. The results indicate that pounding is most critical for highly out-of-phase frames and is not significant for frame period ratios greater than 0.7. Impact models without energy dissipation overestimate the displacement and acceleration amplifications due to impact, especially for elastic behavior of the frames. Representation of stiffness degradation in bridge columns is essential in capturing the accurate response of pounding frames subjected to far field ground motion. Finally, it is shown that strength degradation and pounding can result in significant damage to the stiffer frames of the bridge when subjected to large acceleration pulses from near field ground motion records.

  13. A Simple Analytical Approach to the Aeroelastic Stability Problem of Long-Span Cable-Stayed Bridges

    Science.gov (United States)

    Vairo, Giuseppe

    2010-01-01

    This paper deals with the aeroelastic stability problem of long-span cable-stayed bridges under an approaching crosswind flow. Starting from a continuous model of the fan-shaped bridge scheme with both H- or A-shaped towers, critical states of the coupled wind-structure system are identified by means of a variational formulation, accounting for torsional and flexural (vertical and lateral) bridge oscillations. The overall bridge dynamics is described by introducing simple mechanical systems with equivalent stiffness properties and, under the assumption of a prevailing truss-like bridge behavior, analytical estimates for dominant stiffness contributions are proposed. Several case studies are discussed and comparisons with experimental evidences as well as with available analytical and numerical results are presented. The proposed simplified approach proves to be consistent and effective for successfully capturing the main wind-bridge interaction mechanisms, and it could be considered as a useful engineering tool for the aeroelastic stability analysis of long-span cable-stayed bridges.

  14. Influence of apparent wave velocity on seismic performance of a super-long-span triple-tower suspension bridge

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2015-06-01

    Full Text Available As one of the main characteristics of seismic waves, apparent wave velocity has great influence on seismic responses of long-span suspension bridges. Understanding these influences is important for seismic design. In this article, the critical issues concerning the traveling wave effect analysis are first reviewed. Taizhou Bridge, the longest triple-tower suspension bridge in the world, is then taken as an example for this investigation. A three-dimensional finite element model of the bridge is established in ABAQUS, and the LANCZOS eigenvalue solver is employed to calculate the structural dynamic characteristics. Traveling wave effect on seismic responses of these long-span triple-tower suspension bridges is investigated. Envelopes of seismic shear force and moment in the longitudinal direction along the three towers, relative displacements between the towers and the girder, and reaction forces at the bottoms of the three towers under different apparent wave velocities are calculated and presented in detail. The results show that the effect of apparent wave velocity on the seismic responses of triple-tower suspension bridge fluctuates when the velocity is lower than 2000 m/s, and the effects turn stable when the velocity becomes larger. In addition, the effects of traveling wave are closely related to spectral characteristics and propagation direction of the seismic wave, and seismic responses of components closer to the source are relatively larger. Therefore, reliable estimation of the seismic input and apparent wave velocity according to the characteristics of the bridge site are significant for accurate prediction of seismic responses. This study provides critical reference for seismic analysis and design of long-span triple-tower suspension bridges.

  15. Structural observation of long-span suspension bridges for safety assessment: implementation of an optical displacement measurement system

    Science.gov (United States)

    Lages Martins, L.; Rebordão, J. M.; Silva Ribeiro, A.

    2015-02-01

    This paper addresses the implementation of an optical displacement measurement system in the observation scenario of a long-span suspension bridge and its contribution for structural safety assessment. The metrological background required for quality assurance of the measurements is described, namely, the system's intrinsic parameterization and integration in the SI dimensional traceability chain by calibration, including its measurement uncertainty assessment.

  16. Static behaviors of long-span cable-stayed bridge; Chodai shachokyo no seiteki kyodo ni kansuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Xie, Xu [Saitama Univ., Saitama (Japan). Graduate School; Yamaguchi, H.; Ito, M. [Saitama Univ., Urawa (Japan). Faculty of Engineering

    1996-04-21

    In this study, incremental equation of cable-stayed bridge is formulated by finite element method taking the geometrical nonlinear analysis into account. Then, as an example of designing a bridge with 1500m span, setting up the initial tension, analysis of in-plane behavior caused by live loads as well as analysis of the behavior against wind caused by out-of-plane wind load that are necessary for designing a bridge with 1500m span are carried out. The main results obtained through the study are as follows. As for the cable stayed bridge with 1500m center super long-span having supplementary supporting points between the side arms, the geometrical non-linearity caused by the in-plane design live loads is not remarkable. The effects of wind which acts on girders on analysis of the behaviors against wind are different depending on the aerodynamic performance of the girder and in the case of high wind speed, strong effects on the behavior against wind of the in-plane and screws generate. As the changing of tension of the cable makes influences on the force of in-plane cross section and on displacement of the girder, if the wind speed is very high, the analysis results of the behaviors against wind of in-plane and screws of the cable-stayed bridge may be different depending on in what manner the wind load on the cable to be treated. 16 refs., 16 figs., 1 tab.

  17. Performances of super-long span prestressed cable-stayed bridge with CFRP cables and RPC girder

    Institute of Scientific and Technical Information of China (English)

    Fang Zhi; Fan Fenghong; Ren Liang

    2013-01-01

    To discuss the applicability of advanced composite carbon fiber reinforced polymer (CFRP) and ultra-high performance concrete reactive powder concrete (RPC) in super-long span cable-stayed bridges , taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable’s cross section was determined by the principle of equivalent cable capacity and the girder’s cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resis-tance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.

  18. Stochastic finite element analysis of long-span bridges with CFRP cables under earthquake ground motion

    Indian Academy of Sciences (India)

    Özlem Çavdar; Alemdar Bayraktar; Süleyman Adanur; Hasan Basri Başaǧa

    2010-06-01

    Stochastic seismic analysis of long-span bridges with Carbon fibre reinforced polymer (CFRP) cables are presented in this study through combination of the advantages of the perturbation based stochastic finite element method (SFEM) and Monte Carlo simulation (MCS) method. Jindo cable-stayed and Fatih Sultan Mehmet (Second Bosporus) suspension bridges are chosen as an example. Carbon fibre reinforced polymer cable (CFRP) and steel cables are used separately, in which the cable’s cross sectional area is determined by the principle equivalent axial stiffness. Geometric nonlinear effects are considered in the analysis. Uncertainties in the material are taken into account and Kocaeli earthquake in 1999 is chosen as a ground motion. The efficiency and accuracy of the proposed algorithm are validated by comparing with results of MCS method. It can be stated that using of CFRP cables in long-span bridges subjected to earthquake forces is feasible.

  19. Topographic effects on seismic response of long-span rigid-frame bridge under SV seismic wave

    Institute of Scientific and Technical Information of China (English)

    WANG Lei; ZHAO Cheng-gang; QU Tie-jun

    2008-01-01

    Seismic ground motions of two neighboring mountains and the free surface between them are calculated under the SV seismic waves with three different incident angles. The results are then taken as the inputs of multi-point seismic excitations for the foundation of a long-span bridge built over the valley in the analysis considering the inte-grated influence of traveling wave and topography. On the basis of a dynamic analytical method, a finite element model is created for the seismic responses of a four-span rigid-frame bridge of 440 m. The pier-top displacement and the pier-bottom internal force of the bridge are calculated. Then the results are compared with those considering traveling-wave effect only. The conclusions can serve as a seismic design reference for the structures located on the complex mountain topography.

  20. Topographic effects on seismic response of long-span rigid-frame bridge under SV seismic wave

    Science.gov (United States)

    Wang, Lei; Zhao, Cheng-Gang; Qu, Tie-Jun

    2008-05-01

    Seismic ground motions of two neighboring mountains and the free surface between them are calculated under the SV seismic waves with three different incident angles. The results are then taken as the inputs of multi-point seismic excitations for the foundation of a long-span bridge built over the valley in the analysis considering the integrated influence of traveling wave and topography. On the basis of a dynamic analytical method, a finite element model is created for the seismic responses of a four-span rigid-frame bridge of 440 m. The pier-top displacement and the pier-bottom internal force of the bridge are calculated. Then the results are compared with those considering traveling-wave effect only. The conclusions can serve as a seismic design reference for the structures located on the complex mountain topography.

  1. Seismic response of continuous span bridges through fiber-based finite element analysis

    Institute of Scientific and Technical Information of China (English)

    Chiara Casarotti; Rui Pinho

    2006-01-01

    It is widely recognized that nonlinear time-history analysis constitutes the most accurate way to simulate the response of structures subjected to strong levels of seismic excitation. This analytical method is based on sound underlying principles and has the capability to reproduce the intrinsic inelastic dynamic behavior of structures. Nonetheless,comparisons with experimental results from large-scale testing of structures are still needed, in order to ensure adequate levels of confidence in this numerical methodology. The fiber modelling approach employed in the current endeavor inherently accounts for geometric nonlinearities and material inelasticity, without a need for calibration of plastic hinges mechanisms,typical in concentrated plasticity models. The resulting combination of analysis accuracy and modelling simplicity, allows thus to overcome the perhaps not fully justifiable sense of complexity associated to nonlinear dynamic analysis. The fiberbased modelling approach is employed in the framework of a finite element program downloaded from the Internet for seismic response analysis of framed structures. The reliability and accuracy of the program are demonstrated by numerically reproducing pseudo-dynamic tests on a four span continuous deck concrete bridge. Modelling assumptions are discussed,together with their implications on numerical results of the nonlinear time-history analyses, which were found to be in good agreement with experimental results.

  2. Design of Non-Navigable Span Bridges of Hutong Changjiang River Bridge%沪通长江大桥非通航孔桥设计

    Institute of Scientific and Technical Information of China (English)

    梅新咏; 侯健; 刘琳杰

    2015-01-01

    沪通长江大桥设计通行4线铁路、6车道高速公路,其非通航孔桥为简支钢桁梁结构 ,桥梁跨度112 m ,全长2 912 m ,其中跨南岸大堤桥梁3跨共336 m、跨北岸大堤桥梁2跨共224 m、跨水中横港沙区段桥梁21跨共2 352 m.非通航孔桥主桁为三片钢主桁结构 ,上层公路桥面由钢纵横梁与混凝土桥面板结合而成 ,下层铁路桥面由下弦各节点处的钢横梁与混凝土槽形梁结合而成.桥墩采用钻孔灌注桩基础 ,墩身采用单箱三室的空心钢筋混凝土结构.%The Hutong Changjiang River Bridge is designed to carry 4-track railways and 6-lane expressways .The non-navigable span bridges of the bridge are the simply-supported steel truss girder structures with span length of 112 m .The bridges are totally 2 912 m long ,of which the part of the bridges to cross the river dyke on the south bank has 3 spans and is 336 m long ,to cross the river dyke on the north bank has 2 spans and is 224 m long and to cross the section of the Henggang Islet in the river has 21 spans and is 2 352 m long .T he main trusses of the bridges are the three steel main truss structures .The upper highway decks are the structures composited by the steel stringers ,steel cross beams and concrete deck slabs while the lower railway decks are the ones composited by the steel cross beams at the panel points at the lower chords and the concrete channel girders .T he foundations for the piers of the bridges are all the bored piles and the pier shafts are the reinforced concrete three-cell single-box hollow structures .

  3. Proposal and study of a long-span composite cable-stayed bridge with new hybrid girder; Atarashii gosei kozo shuketa wo mochiita chodai fukugo shachokyo no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K.; Hishiki, Y.; Furuichi, K. [Kajima Corp., Tokyo (Japan)

    1999-09-30

    A hybrid or mixed structure (composite structures) are a matter of increasing concern which takes in each advantage of steel and concrete. A field of bridges is no exception, with the plan and construction carried out for the new type of composite bridge, such as a composite cable-stayed bridge and a composite extra dose bridge as a long span bridge, and a composite truss bridge and a corrugated steel plate web bridge as a medium-span bridge, with technological development becoming active in this field. In such a technological trend, a hybrid two-girder structure was devised, a structure consisting of a concrete filled steel pipe for a girder and a precast (PC) floor plate for a floor board, as the girder structure of a long-span cable-stayed bridge in the subject research; also, applicability was examined using, as an example, the composite cable-stayed bridge with hybrid girders employed for the span. This paper reports the result of the analysis of the entire system, the analysis made for the purpose of examining the characteristic and the feasibility of this hybrid girder. The analysis revealed the structural feasibility of the long-span composite cable-stayed bridge using two hybrid girders of concrete-filled steel pipes thus devised. (NEDO)

  4. Health Monitoring and Evaluation of Long-Span Bridges Based on Sensing and Data Analysis: A Survey.

    Science.gov (United States)

    Zhou, Jianting; Li, Xiaogang; Xia, Runchuan; Yang, Jun; Zhang, Hong

    2017-03-16

    Aimed at the health monitoring and evaluation of bridges based on sensing technology, the monitoring contents of different structural types of long-span bridges were defined. Then, the definition, classification, selection principle, and installation requirements of the sensors were summarized. The concept was proposed that new adaptable long-life sensors could be developed by new theories and new effects. The principle and methods to select controlled sections and optimize the layout design of measuring points were illustrated. The functional requirements were elaborated on about the acquisition, transmission, processing, and management of sensing information. Some advanced concepts about the method of bridge safety evaluation were demonstrated and technology bottlenecks in the current safety evaluation were also put forward. Ultimately, combined with engineering practices, an application was carried out. The results showed that new, intelligent, and reliable sensor technology would be one of the main future development directions in the long-span bridge health monitoring and evaluation field. Also, it was imperative to optimize the design of the health monitoring system and realize its standardization. Moreover, it is a heavy responsibility to explore new thoughts and new concepts regarding practical bridge safety and evaluation technology.

  5. Effect of Soil-Structure Interaction on Seismic Performance of Long-Span Bridge Tested by Dynamic Substructuring Method

    Directory of Open Access Journals (Sweden)

    Zhenyun Tang

    2017-01-01

    Full Text Available Because of the limitations of testing facilities and techniques, the seismic performance of soil-structure interaction (SSI system can only be tested in a quite small scale model in laboratory. Especially for long-span bridge, a smaller tested model is required when SSI phenomenon is considered in the physical test. The scale effect resulting from the small scale model is always coupled with the dynamic performance, so that the seismic performance of bridge considering SSI effect cannot be uncovered accurately by the traditional testing method. This paper presented the implementation of real-time dynamic substructuring (RTDS, involving the combined use of shake table array and computational engines for the seismic simulation of SSI. In RTDS system, the bridge with soil-foundation system is divided into physical and numerical substructures, in which the bridge is seen as physical substructures and the remaining part is seen as numerical substructures. The interface response between the physical and numerical substructures is imposed by shake table and resulting reaction force is fed back to the computational engine. The unique aspect of the method is to simulate the SSI systems subjected to multisupport excitation in terms of a larger physical model. The substructuring strategy and the control performance associated with the real-time substructuring testing for SSI were performed. And the influence of SSI on a long-span bridge was tested by this novel testing method.

  6. Health Monitoring and Evaluation of Long-Span Bridges Based on Sensing and Data Analysis: A Survey

    Directory of Open Access Journals (Sweden)

    Jianting Zhou

    2017-03-01

    Full Text Available Aimed at the health monitoring and evaluation of bridges based on sensing technology, the monitoring contents of different structural types of long-span bridges were defined. Then, the definition, classification, selection principle, and installation requirements of the sensors were summarized. The concept was proposed that new adaptable long-life sensors could be developed by new theories and new effects. The principle and methods to select controlled sections and optimize the layout design of measuring points were illustrated. The functional requirements were elaborated on about the acquisition, transmission, processing, and management of sensing information. Some advanced concepts about the method of bridge safety evaluation were demonstrated and technology bottlenecks in the current safety evaluation were also put forward. Ultimately, combined with engineering practices, an application was carried out. The results showed that new, intelligent, and reliable sensor technology would be one of the main future development directions in the long-span bridge health monitoring and evaluation field. Also, it was imperative to optimize the design of the health monitoring system and realize its standardization. Moreover, it is a heavy responsibility to explore new thoughts and new concepts regarding practical bridge safety and evaluation technology.

  7. Vibration-based monitoring of a 10-meter span composite UHPFRC-carbon fibre-timber bridge mockup

    OpenAIRE

    SIEGERT, D; BEN MEKKI, O; Toutlemonde, F.

    2008-01-01

    This paper deals with the vibration-based damage detection of a 10-meter span composite UHPFRC carbon fibre-timber bridge mockup loaded up to the serviceability limit state (SLS). The effectiveness of the vibration-based monitoring depends on the sensitivity of the modal parameters to local changes in the stiffness of the structure and on the accuracy of the modal parameters estimates. Output-only modal analysis of the transient acceleration signals was carried out using a subspace covariance...

  8. Damper placement for seismic control of super-long-span suspension bridges based on the first-order optimization method

    Institute of Scientific and Technical Information of China (English)

    Billie; F; SPENCER

    2010-01-01

    To ensure the anti-earthquake performances of super-long-span suspension bridges, effective devices should be employed to control the seismic response of key sections. In this paper, four kinds of assessment functions for seismic response control effect are formulated based on the mechanism of seismic response control with dampers and the seismic response characteristics of long-span suspension bridges. A new optimal placement method of dampers using penalty function and first-order optimization theory is then proposed. Runyang suspension bridge (RSB) with a main span of 1490 m is then taken as an example. After seismic response time-history analyses on RSB using different placements of dampers, the analysis results are optimized by employing the optimal placement method and the optimal placements of dampers with the four assessment functions are then achieved respectively. Comparison of the four optimal control effects show that different assessment functions can lead to different optimal placements when the number of dampers is certain, but all placements of dampers can reduce the seismic response of RSB significantly. The selection of assessment functions and damper optimal placement should be determined by the structural characteristics and by what is considered in the structures. Results also show that the first-order optimization is an effective method on determining the optimal placement of dampers.

  9. Numerical simulation of aerodynamic derivatives and critical wind speed for long-span bridges based on simplified steady wind field

    Science.gov (United States)

    Xin, Dabo; Ou, Jinping

    2007-06-01

    Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG k-ɛ turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.

  10. Numerical simulation of aerodynamic derivatives and critical wind speed for long-span bridges based on simplified steady wind field

    Institute of Scientific and Technical Information of China (English)

    Xin Dabo; Ou Jinping

    2007-01-01

    Combining the computational fluid dynamics-based numerical simulation with the forced vibration technique for extraction of aerodynamic derivatives, an approach for calculating the aerodynamic derivatives and the critical flutter wind speed for long-span bridges is presented in this paper. The RNG κ-ε turbulent model is introduced to establish the governing equations, including the continuity equation and the Navier-Stokes equations, for solving the wind flow field around a two-dimensional bridge section. To illustrate the effectiveness and accuracy of the proposed approach, a simple application to the Hume Bridge in China is provided, and the numerical results show that the aerodynamic derivatives and the critical flutter wind speed obtained agree well with the wind tunnel test results.

  11. Modal identification of long-span Runyang Bridge using ambient responses recorded by SHMS

    Institute of Scientific and Technical Information of China (English)

    FEI QingGuo; LI AiQun; HAN XiaoLin; MIAO ChangQing

    2009-01-01

    Runyang Bridge is a newly built cable-supported bridge that crosses the Yangtze River in China.The bridge is composed of one suspension bridge and one cable-stayed bridge.During the construction of the bridge,a structural health monitoring system(SHMS)was installed,which was designed by the Southeast University.Since the bridge was open to traffic,quantities of structural ambient responses have been recorded by the SHMS.And,it's really important to extract structrural information from these records for health monitoring.This paper presents the study on modal identification of the bridge.The dynamic properites including modal frequencies,mode shapes and damping ratios are extracted from the ambient responses.Two identification methods are employed including the enhanced frequency domain decomposition and the stochastic subspace identification.The identified modal parameters from the two methods are compared.Results show that modal frequencies and mode shapes from the two methods are almost the same while the damping ratios are different.

  12. Modal identification of long-span Runyang Bridge using ambient responses recorded by SHMS

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Runyang Bridge is a newly built cable-supported bridge that crosses the Yangtze River in China.The bridge is composed of one suspension bridge and one cable-stayed bridge.During the construction of the bridge,a structural health monitoring system(SHMS)was installed,which was designed by the Southeast University.Since the bridge was open to traffic,quantities of structural ambient responses have been recorded by the SHMS.And,it’s really important to extract structrural information from these records for health monitoring.This paper presents the study on modal identification of the bridge.The dynamic properites including modal frequencies,mode shapes and damping ratios are extracted from the ambient responses.Two identification methods are employed including the enhanced frequency domain decomposition and the stochastic subspace identification.The identified modal parameters from the two methods are compared.Results show that modal frequencies and mode shapes from the two methods are almost the same while the damping ratios are different.

  13. Deck and Cable Dynamic Testing of a Single-span Bridge Using Radar Interferometry and Videometry Measurements

    Science.gov (United States)

    Piniotis, George; Gikas, Vassilis; Mpimis, Thanassis; Perakis, Harris

    2016-03-01

    This paper presents the dynamic testing of a roadway, single-span, cable-stayed bridge for a sequence of static load and ambient vibration monitoring scenarios. Deck movements were captured along both sideways of the bridge using a Digital Image Correlation (DIC) and a Ground-based Microwave Interfererometer (GBMI) system. Cable vibrations were measured at a single point location on each of the six cables using the GBMI technique. Dynamic testing involves three types of analyses; firstly, vibration analysis and modal parameter estimation (i. e., natural frequencies and modal shapes) of the deck using the combined DIC and GBMI measurements. Secondly, dynamic testing of the cables is performed through vibration analysis and experimental computation of their tension forces. Thirdly, the mechanism of cable-deck dynamic interaction is studied through their Power Spectra Density (PSD) and the Short Time Fourier Transform (STFT) analyses. Thereby, the global (deck and cable) and local (either deck or cable) bridge modes are identified, serving a concrete benchmark of the current state of the bridge for studying the evolution of its structural performance in the future. The level of synergy and complementarity between the GBMI and DIC techniques for bridge monitoring is also examined and assessed.

  14. Finite element model updating of multi-span steel-arch-steel-girder bridges based on ambient vibrations

    Science.gov (United States)

    Hou, Tsung-Chin; Gao, Wei-Yuan; Chang, Chia-Sheng; Zhu, Guan-Rong; Su, Yu-Min

    2017-04-01

    The three-span steel-arch-steel-girder Jiaxian Bridge was newly constructed in 2010 to replace the former one that has been destroyed by Typhoon Sinlaku (2008, Taiwan). It was designed and built to continue the domestic service requirement, as well as to improve the tourism business of the Kaohsiung city government, Taiwan. This study aimed at establishing the baseline model of Jiaxian Bridge for hazardous scenario simulation such as typhoons, floods and earthquakes. Necessities of these precaution works were attributed to the inherent vulnerability of the sites: near fault and river cross. The uncalibrated baseline bridge model was built with structural finite element in accordance with the blueprints. Ambient vibration measurements were performed repeatedly to acquire the elastic dynamic characteristics of the bridge structure. Two frequency domain system identification algorithms were employed to extract the measured operational modal parameters. Modal shapes, frequencies, and modal assurance criteria (MAC) were configured as the fitting targets so as to calibrate/update the structural parameters of the baseline model. It has been recognized that different types of structural parameters contribute distinguishably to the fitting targets, as this study has similarly explored. For steel-arch-steel-girder bridges in particular this case, joint rigidity of the steel components was found to be dominant while material properties and section geometries relatively minor. The updated model was capable of providing more rational elastic responses of the bridge superstructure under normal service conditions as well as hazardous scenarios, and can be used for manage the health conditions of the bridge structure.

  15. Research on dynamic characteristics model test scheme for middle pylon of multi-pylon multi-span suspension bridges

    Institute of Scientific and Technical Information of China (English)

    Zhang Yufeng; Zhang Dachang

    2012-01-01

    Multi-pylon multi-span suspension bridge is a new type super flexible structure system, and the rigidity design of middle pylon is one of the main difficult technical issues. Due to the requirements of longitudinal rigidity, the structural form and the corresponding foundation type of middle pylon are different from those of the ordinary steel pylon, and the complicated dynamic characteristics make the calculation quite difficult. In this article, exploration has been made in selection of similarity ratio and model materials, section simulation, restriction conditions simulation, fixing of mass blocks, fabrication scheme and testing method by taking into account different construction and working conditions such as restriction conditions and working environment of a three-pylon suspension bridge, to conduct the test experimental design of the dynamic behavior of the middle pylon, with the purpose to reveal its dynamic characteristics and make comparison and analysis with theoretical assumptions, to provide basis for anti-wind and anti-seismic design and reference for the design and research of three-pylon two-span suspension bridges in the future.

  16. Aerodynamic stability of long span suspension bridges with low torsional natural frequencies

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Johansson, Jens; Brandt, Anders;

    2016-01-01

    Classical flutter of suspended bridge decks can be avoided if the torsional frequencies are lower than the vertical. Wind tunnel tests of single boxes and twin box section models with torsional natural frequencies above and below the vertical frequency has been conducted. Flutter was avoided in a....... In order to design aerodynamically stable suspension bridges with low torsional natural frequencies it is suggested to increase the mass moment of inertia and provide adequate torsional stiffness by the main cables spacing....

  17. Aerodynamic stability of long span suspension bridges with low torsional natural frequencies

    DEFF Research Database (Denmark)

    Andersen, Michael Styrk; Johansson, Jens; Brandt, Anders

    2016-01-01

    Classical flutter of suspended bridge decks can be avoided if the torsional frequencies are lower than the vertical. Wind tunnel tests of single boxes and twin box section models with torsional natural frequencies above and below the vertical frequency has been conducted. Flutter was avoided in all....... In order to design aerodynamically stable suspension bridges with low torsional natural frequencies it is suggested to increase the mass moment of inertia and provide adequate torsional stiffness by the main cables spacing....

  18. Some studies on structural planning of long-span cable stayed bridge; Choshikan shachokyo no kozo keikaku ni kansuru 2,3 no kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Endo, T. [NKK Corp., Tokyo (Japan)

    1997-06-20

    Feasibility of cabled-stayed bridges with 1000m-grade spans is discussed while re-examining the plan for constructing a Great Tatara Bridge to connect Honshu and Shikoku, Japan, and in this process various tasks and questions are isolated. Some which will be problems in designing the new bridge structure are taken up, including the load-bearing capability of the bridge as a whole, vibration of long cables, resistance to long-period earthquakes, and accuracy management during the construction work. Findings are stated below. A cable-stayed bridge is not significantly different from a suspension bridge and is sufficiently feasible until the span exceeds 1500m. When the span is longer, however, the bridge beam cross section needs be designed very prudently in view of the great axial force and wind load to be imposed on it. Effective for the assurance of load-bearing capability for a long-span cabled-stayed bridge is a structure in which load is elastically confined in the direction of the bridge axis. In connection with vibration damping for very long cables, it is verified that a new dimpled cable suits the purpose of suppressing wind load from increasing without reduction in damping effect. 28 refs., 23 figs., 7 tabs.

  19. Perpendicular construction of bridge girder for long span suspension bridge under a rapid stream; Kyuchoryuka ni okeru chodai tsuribashi no hokoketa chokka tsuri koho no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Hirayama, J.; Sakamoto, M.; Nakao, T.; Koga, N. [Honshu-Shikoku Bridge Authority, Tokyo (Japan)

    1996-06-20

    Perpendicular construction of bridge girder for a long span suspension bridge, which is to be constructed over the Kurushima Channel, an international route, has been investigated. For the construction of suspension bridge over channels, the overhang construction is generally employed. Bridge girder perpendicular construction, in which unit girder block is lifted from a carrier barge and directly constructed by means of lifting beams located at main cable, is a superb method in terms of cost, time, and safety. It is necessary to stay the carrier barge during the anchoring of girder block and lifting beams. Mooring of the carrier barge is required under a rapid stream, which results in the trouble of under way ships. A propulsion positioning system has been developed for the bridge girder carrier barge, by which the position/propulsion of four thrusters equipped at each corner of the barge can be automatically controlled. Thus, the perpendicular construction of bridge girder has been developed, in which mooring is not required even under the rapid stream. The position of barge can be maintained within a range of {plus_minus}2.5 m even under a rapid stream with a speed of 3 kn. The quick joint can be certainly connected for about one minute in the horizontal movement within {plus_minus}2.5 m and vertical movement within 0.5 m. For this perpendicular construction, the construction time can be shortened to around 16 to 17 minutes, which has been usually taken for three hours. 2 refs., 17 figs., 4 tabs.

  20. Traveling Wave Resonance and Simplified Analysis Method for Long-Span Symmetrical Cable-Stayed Bridges under Seismic Traveling Wave Excitation

    OpenAIRE

    Zhong-ye Tian; Meng-lin Lou

    2014-01-01

    The seismic responses of a long-span cable-stayed bridge under uniform excitation and traveling wave excitation in the longitudinal direction are, respectively, computed. The numerical results show that the bridge’s peak seismic responses vary significantly as the apparent wave velocity decreases. Therefore, the traveling wave effect must be considered in the seismic design of long-span bridges. The bridge’s peak seismic responses do not vary monotonously with the apparent wave velocity due t...

  1. Coupled Vibration of Long-Span Railway Curved Girder Bridges and Vehicles

    Institute of Scientific and Technical Information of China (English)

    Shan Deshan; Li Qiao

    2005-01-01

    The structure of a long curved girder bridge is represented with a three-dimensional curved finite element model. Each 4-axle vehicle is modeled by a dynamic system of 35 degrees of freedom. The random irregularities of the track are generated from a power spectral density function under the given track condition. The dynamic interaction between the bridge and train is realized through the contact forces between the wheels and track. Then based on these models, the coupled equations of motion are solved by applying the time-integration and iteration techniques to the coupled system. The proposed formulation and the associated computer program are then applied to a real curved girder bridge. The dynamic responses of the bridge-vehicle system and the derailments and offload factors related to the riding and running safeties of vehicles are computed. The results show that the formulation presented in this paper can well predict dynamic behaviors of both bridge and train with reasonable computation efforts.

  2. Numerical computation for aeroelastic stability of long-span bridges; Kyoryo taifu anteisei no kaisekiteki approach

    Energy Technology Data Exchange (ETDEWEB)

    Matsuda, K.; Uejima, H.; Tokushige, M.; Iwasaki, T. [Ishikawajima-Harima Heavy Industries Co. Ltd., Tokyo (Japan)

    1997-11-01

    As bridges increase their size, verifying their aeroelastic stability becomes necessary for design purposes. This paper describes mainly a technology to estimate analytically the aeroelastic stability of bridges. Taking up four kinds of responses as the objects of assessing the aeroelastic stability, the paper introduces analytical approaches to each response. Comparison was made on the analytical values with wind tunnel experiment values, in which reasonability of the analytical approach was verified. Aeroelastic responses consist of (1) static transformation due to wind load, (2) gust response, (3) flutter, and (4) vortex-excited vibration. The item (1) is a static phenomenon of transformation due to steady-state air force generated by a mean component in wind velocity acting on a bridge. The item (2) is a dynamic phenomenon in which irregular vibration is caused as a result of variable component in the wind velocity acting on the bridge. The item (3) increases sharply the amplitude of vibration as a result of small increase in the wind velocity, which is caused once a vibration is generated. The item (4) is a dynamic phenomenon in which a bridge vibrates resonantly due to Karman`s vortex street. The analytic values derived by using respective analytic programs agreed well with the results derived from wind tunnel experiments. 12 refs., 12 figs., 1 tab.

  3. Ultimate strength analysis of long-span cable-stayed bridges; Chodai chachokyo no shukyoku kyodo kaiseki to kyodo ni kansuru ichikosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Xie, X.; Yamaguchi, H. [Saitama Univ., Urawa (Japan)] Nagai, M. [Nagaoka Technical Coll., Niigata (Japan)

    1998-07-21

    Recently, span of cable-stayed bridges has been getting loner and longer, present situation is that cable-stayed bridges with span 600 to 800m class have been built inside and outside the country, and accurate determination of its ultimate strength has been an important problem statistically. However, concrete design method for evaluating load bearing stress of long-span cable-stayed bridge. Particularly of the main beam whose axial stress is dominating, has not been established so far. As for cable-stayed bridge, even for long-span, effect of plasticization of cross section on ultimate strength is severe because there is little effect of geometric nonlinearity and it is thought that accurate evaluation of ultimate strength only by elastic finite potential analysis is difficult. Accordingly, it is necessary to study the behavior by using combined nonlinear analysis considering the nonlinearity of the material in order to evaluate the safety and economy to long-span cable-stayed bridge. In this report, 3 dimensional analysis method was formularized taking into account the combine nonlinearity of multi-box girder and analysis program of ultimate strength behavior of long-span cable-stayed bridge was developed. 19 refs., 17 figs., 2 tabs.

  4. Longitudinal force in continuously welded rail on long-span tied arch continuous bridge carrying multiple tracks

    Institute of Scientific and Technical Information of China (English)

    YAN Bin; DAI Gong-lian; GUO Wen-hua; XU Qing-yuan

    2015-01-01

    Considering arch rib, lateral brace, suspender, girder, pier and track position, the model for the interaction between long-span tied arch continuous bridge and multiple tracks was established by using steel-concrete composite section beam element to simulate concrete-filled steel tube (CFST) arch rib, using the beam element with rigid arm to simulate the prestressed concrete girder and using nonlinear bar element to simulate longitudinal constraint between track and bridge. Taking a (77+3×156.8+77) m tied arch continuous bridge with four tracks on the Harbin-Qiqihar Passenger Dedicated Line as an example, the arrangement of continuously welded rail (CWR) was explored. The longitudinal force in CWR on the tied arch continuous bridge, the pier top horizontal force and torque due to the unbalance load case, were analyzed under the action of temperature, vertical live load, train braking and wind load. Studies show that, it can significantly reduce track displacement to set the track expansion devices at main span arch springing on both sides; the track stress due to arch temperature variation can reach 40.8 MPa; the track stress, pier top horizontal force and torque are related to the number of loaded tracks and train running direction, and the bending force applied to unloaded track is close to the loaded track, while the braking force applied to unloaded track is 1/4 to 1/2 of the loaded track; the longitudinal force of track due to the wind load is up to 12.4 MPa, which should be considered.

  5. Supporting knowledge translation through collaborative translational research initiatives: 'bridging' versus 'blurring' boundary-spanning approaches in the UK CLAHRC initiative.

    Science.gov (United States)

    Evans, Sarah; Scarbrough, Harry

    2014-04-01

    Recent policy initiatives in the UK and internationally have sought to promote knowledge translation between the 'producers' and 'users' of research. Within this paper we explore how boundary-spanning interventions used within such initiatives can support knowledge translation between diverse groups. Using qualitative data from a 3-year research study conducted from January 2010 to December 2012 of two case-sites drawn from the CLAHRC initiative in the UK, we distinguish two different approaches to supporting knowledge translation; a 'bridging' approach that involves designated roles, discrete events and activities to span the boundaries between communities, and a 'blurring' approach that de-emphasises the boundaries between groups, enabling a more continuous process of knowledge translation as part of day-to-day work-practices. In this paper, we identify and differentiate these boundary-spanning approaches and describe how they emerged from the context defined by the wider CLAHRC networks. This highlights the need to develop a more contextualised analysis of the boundary-spanning that underpins knowledge translation processes, relating this to the distinctive features of a particular case.

  6. RESEARCH ON THE ASEISMIC BEHAVIOR OF LONG-SPAN CABLE-STAYED BRIDGE WITH DAMPING EFFECT

    Directory of Open Access Journals (Sweden)

    Wu Fangwen

    2016-07-01

    Full Text Available The main beam of a cable-stayed bridge with a floating system may have a larger longitudinal displacement subject to earthquake effect. Thus, seismic control and isolation are crucial to bridge safety. This paper takes Huai’an Bridge, which has elastic coupling devices and viscous dampers set at the joint of the tower and the beam, as the research background. Its finite element model is established, and the elastic stiffness of elastic coupling devices and damper parameters are analyzed. Viscous damper and elastic coupling devices are simulated using Maxwell model and spring elements, and their damping effects are analyzed and compared through structural dynamic time-history analysis. Results show that viscous damper and elastic coupling device furnished at the joint of tower and beam of a cable-stayed bridge tower beam can effectively reduce the longitudinal displacement of the key part of the construction subject to earthquake effect, perfect the internal force distribution, and improve the aseismic performance. Between the two, viscous damper has better damping effects.

  7. A comparative study between China and U.S. on seismic design philosophy and practice of a long span arch bridge

    Institute of Scientific and Technical Information of China (English)

    Xu Yan; George C Lee; Fan Lichu; Hu Shide

    2006-01-01

    This paper presents the first of a series of case studies on the seismic design of long span bridges (cablestayed bridges, suspension bridges and arch bridges) under a cooperative research project on seismic behavior and design of highway bridges between the State Key Laboratory for Disaster Reduction in Civil Engineering, Tongji University and the Multidisciplinary Center for Earthquake Engineering Research, University at Buffalo. The objective of this series of case studies is to examine the differences and similarities on the seismic design practice of long span bridges in China and the U.S., to identify research needs and to develop design guidelines beneficial to bridge engineers in both countries. Unlike short to medium span bridges, long span bridges are not included in most seismic design specifications, mainly because they are location dependent and structurally unique. In this paper, an available model of a steel tied half through arch bridge with a main span of 550m in China is discussed. Analysis is focused on comparisons of the seismic responses due to different ground motions. Seismic design criteria and seismic performance requirements for long span bridges in both countries were first introduced and compared, and then three near field earthquake records with large vertical components were selected as the excitations to examine the seismic behavior and seismic vulnerability of the bridge. Results show that (1) the selected near field ground motions cause larger responses to key components (critical sections) of the bridge (such as arch rib ends) with a maximum increase of more than twice those caused by the site specific ground motions; (2) piers, longitudinal girders and arch crowns are more vulnerable to vertical motions, especially their axial forces; and (3) large vertical components of near field ground motions may not significantly affect the bridge's internal forces provided that their peak acceleration spectra ordinates only appear at periods

  8. 大跨径桥梁施工控制不确定因素分析%Analysis of the Uncertain Factors of Long Span Bridge Construction Control

    Institute of Scientific and Technical Information of China (English)

    徐志学

    2014-01-01

    There are many uncertain factors affecting the bridge construction quality in the process of long-span bridge construction. This article mainly analyzes the temperature eff-ect, temperature load and some control methods of the long-span bridge construction, and reduces the influence of unc-ertain factors on the quality of long-span bridges.%在大跨径桥梁施工过程中,有许多不确定因素影响着桥梁的施工质量。本文对温度效应、温度载荷以及大跨径桥梁施工过程中的一些控制方法进行了分析,降低了不确定因素对大跨径桥梁的质量影响。

  9. Analysis on influence of seismic travelling wave effect on semi-active control for long-span rigid-continuous bridge

    Institute of Scientific and Technical Information of China (English)

    QI Xing-jun; LI Xiao-jun; ZHOU Guo-liang

    2006-01-01

    The analysis approach of semi-active control for long-span rigid-continuous bridge under seismic travelling wave input is established. Magnetorheological dampers are set on the positions of the bridge bearings. The semi-active control calculation and analysis are performed for a five-span rigid-continuous bridge under seismic travelling waves with different apparent surface velocities. The results indicate that travelling wave effect remarkably influences the uncontrolled seismic responses, the semi-active control seismic responses and vibration control effects for the long-span rigid-continuous bridge. It is disadvantageous to the responses of the beams and the piers under the travelling wave input with lower apparent surface velocity, and travelling wave effect can decrease the vibration control effects evidently. Therefore, the travelling wave effect should be considered for the selection of the parameter values of semi-active control system in order to get the designing control effect.

  10. Dynamic analysis and modal test of long-span cable-stayed bridge based on ambient excitation

    Institute of Scientific and Technical Information of China (English)

    CHEN Chang-song; YAN Dong-huang

    2007-01-01

    To study the stifilless distilbution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs.Based on the simplified model four stiffness formulae were deduced according to Hamilton principle.These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively.An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation.The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge.The results show that the errors of frequencies between theoretical analysis and test results are less than 10%mostly,and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stifiness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.

  11. Dynamic Performance Analysis of the Towers of a Long-Span Bridge Based on GPS Monitoring Technique

    Directory of Open Access Journals (Sweden)

    Mosbeh R. Kaloop

    2016-01-01

    Full Text Available The present study investigates the parameter identification and the dynamic performance of a long-span bridge tower based on the output of a global positioning system (GPS health monitoring system. The random decrement (RD algorithm is used to estimate the tower displacement impulse response. Three methods are applied to extract the dynamic performance including least squares complex exponential (LSCE method, Hilbert envelope method (HEM, and eigensystem realization algorithm (ERA. Results reveal that the HEM and LSCE method are more suitable to extract fundamental frequency and modal and damping ratios of the tower. Furthermore, the dynamic properties and statistical time series analysis of the GPS measurements illustrate that the traffic loads have a high significant impact on the semistatic and dynamic performances.

  12. Vibration control of tower of long span suspension bridge; Chodai tsuribashi shuto no seishin gijutsu

    Energy Technology Data Exchange (ETDEWEB)

    Kubota, H.; Miyazaki, M. [Sumitomo Heavy Industries, Ltd., Tokyo (Japan); Sasaki, M. [Bridge and Offshore Engineering Association, Tokyo (Japan); Fumoto, K. [Honshu-Shikoku Bridge Authority, Tokyo (Japan)

    1998-08-20

    This paper describes the vibration control during the erection of 8P main tower of Kurushima-ohashi Bridge. Since the body of tower crane and the crane post were adjacent to the main tower, stability against wind due to the change of separation flow was worried. Response characteristics and design data for the damper were obtained through the wind tunnel tests. Since the vibration characteristics change in each erection step, generation of vortex excitation was examined in various modes. An active mass damper (AMD) was applied to the tower surface radial bending primary vibration, of which natural frequency changes in a wide range at the wind velocity below working limit, and the other vibration modes. A tuned mass damper (TMD) was also used in the mode where large damping energy is required under the high wind velocity and high frequency conditions. For the rolling pendulum type AMD, a servo-motor driving carriage moves on the frame rail, and a restitutive force is obtained with rotating the fan type rolling element pin-supported on the carriage. The natural frequency of AMD can be adjusted by fan shaped plural weight plates. Variable gain type DVFB control was employed, in which displacement and velocity of the damper are used as the control output. Sufficient functions could be obtained. 7 refs., 4 figs., 5 tabs.

  13. Traveling Wave Resonance and Simplified Analysis Method for Long-Span Symmetrical Cable-Stayed Bridges under Seismic Traveling Wave Excitation

    Directory of Open Access Journals (Sweden)

    Zhong-ye Tian

    2014-01-01

    Full Text Available The seismic responses of a long-span cable-stayed bridge under uniform excitation and traveling wave excitation in the longitudinal direction are, respectively, computed. The numerical results show that the bridge’s peak seismic responses vary significantly as the apparent wave velocity decreases. Therefore, the traveling wave effect must be considered in the seismic design of long-span bridges. The bridge’s peak seismic responses do not vary monotonously with the apparent wave velocity due to the traveling wave resonance. A new traveling wave excitation method that can simplify the multisupport excitation process into a two-support excitation process is developed.

  14. a Method for the Extraction of Long-Term Deformation Characteristics of Long-Span High-Speed Railway Bridges Using High-Resolution SAR Images

    Science.gov (United States)

    Jia, H. G.; Liu, L. Y.

    2016-06-01

    Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR) technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

  15. A METHOD FOR THE EXTRACTION OF LONG-TERM DEFORMATION CHARACTERISTICS OF LONG-SPAN HIGH-SPEED RAILWAY BRIDGES USING HIGH-RESOLUTION SAR IMAGES

    Directory of Open Access Journals (Sweden)

    H. G. Jia

    2016-06-01

    Full Text Available Natural causes and high-speed train load will result in the structural deformation of long-span bridges, which greatly influence the safety operation of high-speed railway. Hence it is necessary to conduct the deformation monitoring and regular status assessment for long-span bridges. However for some traditional surveying technique, e.g. control-point-based surveying techniques, a lot of human and material resources are needed to perform the long-term monitoring for the whole bridge. In this study we detected the long-term bridge deformation time-series by persistent scatterer interferometric synthetic aperture radar (PSInSAR technique using the high-resolution SAR images and external digital elevation model. A test area in Nanjing city in China is chosen and TerraSAR-X images and Tandem-X for this area have been used. There is the Dashengguan bridge in high speed railway in this area as study object to evaluate this method. Experiment results indicate that the proposed method can effectively extract the long-term deformation of long-span high-speed railway bridge with higher accuracy.

  16. EarthCube - Earth System Bridge: Spanning Scientific Communities with Interoperable Modeling Frameworks

    Science.gov (United States)

    Peckham, S. D.; DeLuca, C.; Gochis, D. J.; Arrigo, J.; Kelbert, A.; Choi, E.; Dunlap, R.

    2014-12-01

    In order to better understand and predict environmental hazards of weather/climate, ecology and deep earth processes, geoscientists develop and use physics-based computational models. These models are used widely both in academic and federal communities. Because of the large effort required to develop and test models, there is widespread interest in component-based modeling, which promotes model reuse and simplified coupling to tackle problems that often cross discipline boundaries. In component-based modeling, the goal is to make relatively small changes to models that make it easy to reuse them as "plug-and-play" components. Sophisticated modeling frameworks exist to rapidly couple these components to create new composite models. They allow component models to exchange variables while accommodating different programming languages, computational grids, time-stepping schemes, variable names and units. Modeling frameworks have arisen in many modeling communities. CSDMS (Community Surface Dynamics Modeling System) serves the academic earth surface process dynamics community, while ESMF (Earth System Modeling Framework) serves many federal Earth system modeling projects. Others exist in both the academic and federal domains and each satisfies design criteria that are determined by the community they serve. While they may use different interface standards or semantic mediation strategies, they share fundamental similarities. The purpose of the Earth System Bridge project is to develop mechanisms for interoperability between modeling frameworks, such as the ability to share a model or service component. This project has three main goals: (1) Develop a Framework Description Language (ES-FDL) that allows modeling frameworks to be described in a standard way so that their differences and similarities can be assessed. (2) Demonstrate that if a model is augmented with a framework-agnostic Basic Model Interface (BMI), then simple, universal adapters can go from BMI to a

  17. Experimental and Analytical Investigation of Deformations and Stress Distribution in Steel Bands of a Two-Span Stress-Ribbon Pedestrian Bridge

    Directory of Open Access Journals (Sweden)

    G. Sandovic

    2017-01-01

    Full Text Available The article is dedicated to the analysis of problems related to design of pedestrian bridges with flexible ribbon bands made of steel. The study is based on test results of a bridge model that has two spans (each with a length of five meters. A simplified analytical technique has been proposed for predicting vertical deformations of the bridge structure subjected to symmetrical or asymmetrical loading patterns. The technique also allows assessing the tension forces in the ribbons, which are very important for design of such structures. The analysis reveals the importance of the flexural rigidity of the ribbons that might cause significant redistribution of stresses within the steel bands.

  18. Wind resistance challenges and fundamental research on long-span bridges%大跨度桥梁抗风技术挑战与基础研究

    Institute of Scientific and Technical Information of China (English)

    项海帆; 葛耀君

    2011-01-01

    With the rapid development of long span bridges in China, this paper focused on some engineering projects related to wind resistance challenges on three types of long span bridges, including flutter instability and control of suspension bridges, wind induced vibration of cable-stayed bridges and control of wind-rain induced cable vibration, vortex shedding vibration and control of arch bridges, and the refinements on aerodynamic flutterand buffeting of super long span bridges. It can be concluded that the intrinsic limit of span length due to aerodynamic stability is about 1 500 m for a traditional suspension bridge, and beyond or even approaching this limit, designers should be prepared to improve aerodynamic stability. The long-span cable-stayed bridges with a 1 000 m main span have high enough critical flutter speed, but the main aerodynamic concern is rain-wind induced vibration of long stay cables. Except one example of vortex-induced vibration, long-span arch bridges have no wind resistance problems. The fundamental research on wind resistance of long-span bridges was also introduced with the full-mode flutter analysis method as 3D bridge flutter precise analysis, the bridge buffeting frequency-domain analysis under skew wind action, the bridge flutter and buffeting reliability evaluation method based on second order theory and first passage theory, and the unveiling of bridge flutter evoluation process, generation mechanism and control law.%以我国30年大跨度桥梁的快速发展为研究背景,对3种大跨度桥梁的抗风技术挑战进行了基础性研究和应用性研究,着重探讨了悬索桥的颤振性能及其控制、斜拉桥风振性能与拉索风雨振控制、拱式桥涡激共振及其控制、特大桥梁风振精细化理论等一系列抗风关键问题.研究结果表明:悬索桥的颤振稳定性跨径上限约为1 500m,超过甚至接近这一上限时,必须采取措施改善加劲梁的抗风稳定性;千米级大跨度斜

  19. Study on wind resistant design of long-span bridges based on field observation result; Dotai kansoku kekka ni motozuku chodaikyo no taifu sekkei ni kansuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Katsuchi, H.; Tada, K.; Kitagawa, M.

    1996-07-21

    Based on records of strong wind and bridge response to the 19th typhoon in 1991 and 13th typhoon in 1993 at the Onaruto Bridge and the Minami Bisan-Seto Bridge as well as results of numerical analysis, the validity of wind resistant design was investigated. The validity of current wind resistant design was confirmed for the intensity of turbulence and the power spectrum among the natural wind properties. The spatial correlation property was expressed better by Karman`s correlation equation than by usual exponential function equation. The bridge response value was evaluated well by using Karman`s correlation equation, as to bridge response properties, and especially the gust response properties. It was more rational to apply Karman`s correlation equation rather than usual exponential equation to the wind resistant design of long-span bridges. It was suggested that the evaluation of the wind load in the wind resistant design can be reduced. Accordingly, the design of long-span bridges, whose structures can be determined by the wind load, can be rationalized. 20 refs., 13 figs., 2 tabs.

  20. Evaluation of damping property of long-span prestressed concrete cable-stayed bridges; Chodai PC shachokyo no gensui tokusei ni kansuru kosatsu

    Energy Technology Data Exchange (ETDEWEB)

    Yamanobe, S.; Niihara, Y.; Minami, H.; Kono, T. [Kajima Corp., Tokyo (Japan)

    1999-09-30

    As to the dynamic design in the antiseismic design of PC cable-stayed bridges, evaluation of damping is important. Since it is difficult to evaluate damping property theoretically and analytically, a lot of studies have not been made about how to set up damping coefficients. In this study, using analytical models of existing long-span PC cable-stayed bridges, to clarify causes of damping of long-span PC cable-stayed bridge, the rate of strain energy in each member was examined. Equivalent damping coefficients of each member, effects of friction in movable bearing, and effects of basically radiational damping were studied. The correspondence with the results of the vibration experiments conventionally made were studied. (translated by NEDO)

  1. Reduction of seismic response long-span PC cable-stayed bridge by passive dampers; Damper ni yoru saidai PC shachokyo no jishinji oto no teigen

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, T.; Yamanobe, S.; Niihara, Y. [Kajima Corp., Tokyo (Japan)

    1994-10-31

    It is important in designing a PC cable-stayed bridge to properly estimate the seismic response of the bridge for reduction of the response. In this paper, an improvement of the seismic resistance of PC cable-stayed bridges when dampers are installed between the deck and piers and lateral vibration of the deck is restricted is investigated using a time history response model. PC cable-stayed bridges with a span length of 400 m, particularly two types of bridges of harp and semi-harp are investigated and the following is found by analyzing the case where there are installed hysteresis type dampers (with 1 cm yield displacement and secondary rigidity assumed to be 1/10 times that of initial rigidity, the initial rigidity being parametrically changed.) or viscous type dampers (a damping factor is changed.) The result shows that the dampers can reduce the seismic response of a PC cable-stayed bridge and that a semi-harp configuration of stay cables where stay cable members are substantially vertically arranged is more effective than a harp configuration for the seismic performance of PC cable-stayed bridges. The damper partly bear inertial force of the bridge upon earthquake whereby tension of the stay cable members is reduced and bending moment of the deck is reduced. There is existing an optimum characteristic value of the damper concerning the bending moment of the piers. 5 refs., 7 figs., 2 tabs.

  2. 中、小跨径混凝土梁桥健康监测研究%Health Monitoring Research on Medium and Small Span Concrete Beam Bridge

    Institute of Scientific and Technical Information of China (English)

    李祥辉

    2012-01-01

    The necessity and significance of conducting health monltonng resea, c,, ~ concrete beam bridge are discussed. Taking an actual bridge as an example, the standard, specific procedures and methods of building health monitoring system of medium and small span concrete bridge are introduced, with certain reference for discussion of health monitoring of such bridges.%论述了对中、小跨径混凝土梁桥实施健康监测的必要性及意义,以一座实际桥梁为例,介绍了中、小跨径桥梁健康监测系统建立的准则、具体步骤以及方法,对该类型桥梁的健康监测具有一定的参考意义。

  3. Effects of fundamental factors on coupled vibration of wind-rail vehicle-bridge system for long-span cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    张明金; 李永乐; 汪斌

    2016-01-01

    In a wind-vehicle-bridge (WVB) system, there are various interactions among wind, vehicle and bridge. The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors, such as mean wind, fluctuating wind, buffeting, rail irregularities, light rail vehicle vibration and bridge stiffness. A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example. Firstly, a finite element model is built for the long cable-stayed bridge. The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements. Vehicles are modeled as mass-spring-damper systems. Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method. Then, aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests. Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method. Finally, dynamic responses of the WVB system are analyzed in a series of cases. The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent. The transverse forces of wheel axles mainly depend on the track irregularity. The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness. And the accelerations of the bridge are enlarged after adding the fluctuating wind.

  4. 基于UHPC的超大跨径桥梁优化设计%Optimal Design of Ultra-long Span Bridge Based on UHPC

    Institute of Scientific and Technical Information of China (English)

    闫军祥

    2016-01-01

    In order to solve the problems in long span bridge of conventional concrete, such as easily cracking of box girder, limited span (under 300 m), Ultra-high Performance Concrete (UHPC) has been introduced to the design of ultra-long span bridge. A new type structure of continuous box girder contain thin-wall structure and dense diaphragm plates has been design. Obtain the optimal distance is 4m of dense diaphragm plates and optimal span ratio is 0.6 through performance analysis and optimization design. Research finding the UHPC bridge has the advantages of strong sustainability, long service life through contrastive analysis of UHPC bridge design scheme and entity arch bridge. The design of UHPC bridge provide a new method for ultra-long continuous box girder bridge.%为了解决常规混凝土下大跨径桥梁出现的箱梁易开裂,主跨径难以突破300 m等问题,将超高性能混凝土(ultra-high performance concrete,UHPC)引用至超大跨径的桥梁设计当中,形成了一种集薄壁结构、密集横隔板箱梁于一体的新型连续梁结构,并对横隔板参数和跨径比进行优化,确定最佳横隔板间隔为4 m,跨径比为0.6。将UHPC箱体桥梁设计方案与某实体桥梁进行对比分析,发现UHPC桥梁具有可持续性强、使用寿命长等优点,为超大跨径连续箱体桥梁设计提供了一个新的方法。

  5. Using BIM to Improve the Design and Construction of Bridge Projects: A Case Study of a Long-span Steel-box Arch Bridge Project

    OpenAIRE

    Wenping Liu; Hongling Guo; Heng Li; Yan Li

    2014-01-01

    More and more mega-complex bridge projects are being or will be built worldwide. At the same time, the design and construction of such projects involve more and more challenges, e.g., complex structural designs, complicated construction environments, etc. This research study aims to apply BIM (Building Information Modelling) to bridge projects to improve the efficiency and effectiveness of design and construction. Through the analysis of the characteristics of bridge projects and relevant, as...

  6. On flutter stability of decks for super long-span bridge; Cho chodai tsurihashi hogoko no furatta anteika ni kansuru kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    Matsumoto, M. [Kyoto Univ. (Japan). Faculty of Engineering; Hamazaki, H. [Fuji Research Inst. Corp., Tokyo (Japan); Yoshizumi, F. [Kyoto Univ., Kyoto (Japan). Graduate School

    1996-04-21

    In recent years, with the development of high strength steel, long span suspension-bridge becomes possible, furthermore, with the progress of welding technology, the horizontal deformation and torsional deformation of the deck increase owing to the reduction of energy dissipation due to sliding friction. Because of this, super long-span bridge is easy to get vibrated by wind, stability measures having more excellent wind resistance become necessary. In this study, aiming at controlling the pattern of air flow around the sections of box-form girder of super long-span bridge, studied were conducted on deck sections having more excellent flutter stability. Studied were conducted on the relationship between torsional vibration and flexible vibration coupled with unsteady aerodynamic force coefficience at the occurrence of flutter and the occurring mechanism of the flutter was cleared. The characteristics of the aerodynamic force of box-form girder having oval section, rectangle section with center barrier, anti-triangle section and tandem oval section respectively were studied and the results were reported. 10 refs., 25 figs.

  7. 港珠澳大桥浅水区非通航孔桥组合梁设计%Design of Composite Girders for Non-Navigable Span Bridge of Hong Kong-Zhuhai-Macau Bridge in Shallow Water Area

    Institute of Scientific and Technical Information of China (English)

    罗扣; 王东晖; 张强

    2013-01-01

    The main part of the Hong Kong-Zhuhai-Macau Bridge is a part of the combined bridge and tunnel,of which the non-navigable span bridge in the shallow water area is the 85 m span continuous composite girder bridge that totally has 64 spans of the composite girders and is 5 440 m in length.The span arrangement of the bridge mainly includes two kinds of arrangement of 6)× 85 m and 5)× 85 m.The composite girders are the separated continuous single-cell singlebox girders with constant depth and specifically are composed of the open steel box girders and the concrete deck slabs that are connected each other via shear studs.A steel box girder is the inverted trapezoid structure,a concrete deck slab is the precast full slab in the transverse direction and the grooves are pre-reserved at the locations of the shear studs.To improve the transverse mechanical behavior of the deck slabs,the stringers are set in the sections of the composite girders and to keep the integrity of the slabs,the shear studs are arranged in a way of clustering.The composite girders are erected and installed in each full span by the large transportation and erection floating crane and the girders are closed span by span.%港珠澳大桥主体工程采用桥隧组合方案,其中浅水区非通航孔桥采用85 m连续组合梁桥形式,全长5 440m,共64孔,跨径布置主要采用6×85 m和5×85m2种形式.组合梁采用单箱单室分幅等高连续梁,由开口钢箱梁和混凝土桥面板通过剪力钉联结而成.钢箱梁为倒梯形结构;混凝土桥面板为横向整块预制,在剪力钉处设置预留槽.为改善混凝土桥面板的横向受力性能,该桥组合梁截面设置小纵梁;为保持桥面板的整体性,剪力钉采用集束式布置方式.组合梁采用大型运架一体浮吊整孔安装架设,逐孔合龙.

  8. Impact coefficient and reliability of mid-span continuous beam bridge under action of extra heavy vehicle with low speed

    Institute of Scientific and Technical Information of China (English)

    刘波; 王有志; 胡朋; 袁泉

    2015-01-01

    To analyze the dynamic response and reliability of a continuous beam bridge under the action of an extra heavy vehicle, a vehicle–bridge coupled vibration model was established based on the virtual work principle and vehicle–bridge displacement compatibility equation, which can accurately simulate the dynamic characteristics of the vehicle and bridge. Results show that deck roughness has an important function in the effect of the vehicle on the bridge. When an extra heavy vehicle passes through the continuous beam bridge at a low speed of 5 km/h, the impact coefficient reaches a high value, which should not be disregarded in bridge safety assessments. Considering that no specific law exists between the impact coefficient and vehicle speed, vehicle speed should not be unduly limited and deck roughness repairing should be paid considerable attention. Deck roughness has a significant influence on the reliability index, which decreases as deck roughness increases. For the continuous beam bridge in this work, the reliability index of each control section is greater than the minimum reliability index. No reinforcement measures are required for over-sized transport.

  9. Application of Wireless Monitoring System to Structural Health Monitoring of Long-Spanned Cable-Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    MENG Qing-cheng; QI Xin; Li Qiao

    2007-01-01

    The remote monitoring system applied to the construction control and health monitoring of the Nanjing Third Yangtze River Bridge is introduced. The system makes it possible to get the structure capabilities and environmental parameters of the bridge at the predetermined moment. It sends the collected data over a long distance to an assigned position for display and analysis. The related methods and working condition of the wireless monitoring system are discussed. The measured data during 48 h are employed to determine the feasibility for the closure of the bridge.

  10. Using BIM to Improve the Design and Construction of Bridge Projects: A Case Study of a Long-span Steel-box Arch Bridge Project

    Directory of Open Access Journals (Sweden)

    Wenping Liu

    2014-08-01

    Full Text Available More and more mega-complex bridge projects are being or will be built worldwide. At the same time, the design and construction of such projects involve more and more challenges, e.g., complex structural designs, complicated construction environments, etc. This research study aims to apply BIM (Building Information Modelling to bridge projects to improve the efficiency and effectiveness of design and construction. Through the analysis of the characteristics of bridge projects and relevant, associated problems, a BIM-based solution to improving design and construction is developed, including conceptual design optimization, detailed design optimization, the optimization of construction sequences, construction scheduling, construction management, and construction process monitoring. Furthermore, a real-life bridge project is presented to demonstrate the feasibility and validity of the BIM-aided approach to design and construction. It is shown that BIM has the potential to improve the design and construction of bridge projects. It is expected that this research could contribute to the extensive application of BIM in mega-complex bridge projects to aid in design and construction in the future.

  11. Dynamic response of a long span suspension bridge and running safety of a train under wind action

    Institute of Scientific and Technical Information of China (English)

    GUO Weiwei; XIA He; XU Youlin

    2007-01-01

    A dynamic analysis model of a wind-train-bridge system is established.The wind excitations of the system are the buffeting and self-excited forces simulated in time domain using measured aerodynamic coefficients and flutter derivatives.The proposed formulations are then applied to a long rail-cum-road suspension bridge.The dynamic responses of the bridge and the train under wind action are analyzed.The results show that the lateral and rotational displacements of the bridge are dominated by wind,while the vertical by the gravity loading of the moving train.The running safeties of the train vehicles are much affected by wind.Under wind conditions of 30-40 m/s,the offioad factors,derail factors and overturn factors of the train vehicles exceed the safety allowances,to which great attention should be paid.

  12. Structural Behavior of a Long-Span Partially Earth-Anchored Cable-Stayed Bridge during Installation of a Key Segment by Thermal Prestressing

    Directory of Open Access Journals (Sweden)

    Sang-Hyo Kim

    2016-08-01

    Full Text Available This study investigated structural behavior of long-span partially earth-anchored cable-stayed bridges with a main span length of 810 m that use a new key segment closing method based on a thermal prestressing technique. A detailed construction sequence analysis matched with the free cantilever method (FCM was performed using a three-dimensional finite element (FE model of a partially earth-anchored cable-stayed bridge. The new method offers an effective way of connecting key segments by avoiding large movements resulting from the removal of the longitudinal restraint owing to the asymmetry of axial forces in the girders near the pylons. The new method develops new member forces through the process of heating the cantilever system before installing the key segment and cooling the system continuously after installing key segments. The resulting forces developed by the thermal process enhance the structural behavior of partially earth-anchored cable-stayed bridges owing to decreased axial forces in the girders.

  13. Field Testing and Load Rating Report for Bridge No. 4, Hybrid Composite Beam Span, at Fort Knox, Kentucky

    Science.gov (United States)

    2016-09-01

    metal guardrail as the military vehicles crossed the structure ; especially during the first tests run near the structure’s edges (Test Paths Y1 & Y3...were the first time these details were heavily loaded. In general, this type of behavior is common for newer structures and does not affect the...Composite Beams for Bridges for Project F12-AR15, “Corrosion-Resistant Hybrid Composite Bridge Beams for Structural Applications” Monitored by

  14. 高地震烈度地区大跨度桥梁桩基础设计%The Pile Disign of Wide- span Bridge for High- intensity Earthquake Area

    Institute of Scientific and Technical Information of China (English)

    屈国

    2011-01-01

    The paper introduces the speciality of the pile disign of wide - span bridge in high - intensity earthquake area base on one wide -span cable -stayed bridge and give some suggestion.%结合某大跨度斜拉桥工程,介绍了高地震烈度地区大跨度桥梁桩基础设计的特殊性,提出合理建议。

  15. The random field model of the spatial distribution of heavy vehicle loads on long-span bridges

    Science.gov (United States)

    Chen, Zhicheng; Bao, Yuequan; Li, Hui

    2016-04-01

    A stochastic model based on Markov random field is proposed to model the spatial distribution of vehicle loads on longspan bridges. The bridge deck is divided into a finite set of discrete grid cells, each cell has two states according to whether the cell is occupied by the heavy vehicle load or not, then a four-neighbor lattice-structured undirected graphical model with each node corresponding to a cell state variable is proposed to model the location distribution of heavy vehicle loads on the bridge deck. The node potential is defined to quantitatively describe the randomness of node state, and the edge potential is defined to quantitatively describe the correlation of the connected node pair. The junction tree algorithm is employed to obtain the systematic solutions of inference problems of the graphical model. A marked random variable is assigned to each node to represent the amplitude of the total weight of vehicle applied on the corresponding cell of the bridge deck. The rationality of the model is validated by a Monte Carlo simulation of a learned model based on monitored data of a cable-stayed bridge.

  16. 跨铁路站场斜拉桥荷载试验分析%Analysis on Loading Test of Cable-stayed Bridge Spanning Railway Station

    Institute of Scientific and Technical Information of China (English)

    刘邵平

    2011-01-01

    和平大桥位于城市主干道上,跨越徐州铁路站场,铁路交通量极大。为了检验成桥后该桥梁承载能力是否满足正常使用状况的要求以及评估实际结构的动力性能,对全桥展开荷载试验分析。研究结果表明,和平大桥的受力性能和正常使用状态极限承载力满足设计荷载等级城-A级要求,结构工作状况良好。%Heping bridge with heavy-volume traffic is located at urban arterial road and spans a railway station.To test wheather the bearing capacity under normal service loading could meet criterion or not and evaluate the dynamic characteristics of the bridge,loading test analysis is proposed in this paper.The results show that the mechanical behavior and the ultimate bearing capacity under normal service loading of Heping bridge meet the design load grade-A standard and Heping bridge is in good working condition.

  17. 大跨径人行桥人致振动舒适度分析%Analysis for Comfort of Pedestrian-induced Vibration on Large-span Pedestrian Bridges

    Institute of Scientific and Technical Information of China (English)

    傅科奇; 胡佐平; 王成树

    2015-01-01

    人行桥的主要荷载源于行人和非机动车,对于大跨径轻柔桥梁结构,在行人激励之下更容易发生大幅振动,引起舒适度问题。依托国内某大跨径人行提篮拱桥,参考国外人行桥设计指南,通过有限元时程分析方法,计算获得不同荷载激励下结构最大加速度响应时程曲线,进行行人振动舒适度评价。另外,针对不同模态设计相应的TMD减振系统,并进行减振效果分析。%Main loads of pedestrian bridges come from pedestrians and non-motor vehicles,and large-span soft bridge structures under motivation of pedestrians are more vulnerable to large vibration to cause comfort problem.Dependent on a domestic large-span pedestrian X-style arch bridge and by reference to foreign guide for design of pedestrian bridges, this paper calculates and obtains the maximum. acceleration response time-history curve of structures under motivation of different loads by means of finite element time -history analysis method to evaluate comfort under pedestrian vibration.in addition,the paper designs corresponding TMD vibration damping systems against different modes and analyzes damping effect.

  18. Nonlinear Stability Analysis of Long-Span Continuous Rigid Frame Bridge with Thin-Wall High Piers

    Institute of Scientific and Technical Information of China (English)

    Li Li; Peng Yuancheng; Long Xiaohong; Liao Ping

    2005-01-01

    By utilizing the current finite element program ANSYS, two types of finite element models (FEM), the beam model (BM) and shell model (SM), are established for the nonlinear stability analysis of a practical rigid frame bridge-Longtanhe Great Bridge. In these analyses, geometrical and material nonlinearities are simultaneously taken into account. For geometrical nonlinearity, updated Lagrangian formulations are adopted to derive the tangent stiffness matrix. In order to simulate the nonlinear behavior of the plastic hinge of the piers, the multi-lines spring element COMBIN39 is used in the SM while the bilinear rotational spring element COMBIN40 is employed in the BM. Numerical calculations show that satisfying results can be obtained in the stability analysis of the bridge when the double coupling nonlinearity effects are considered. In addition, the conclusion is significant for practical engineering.

  19. Health monitoring data analysis and comparison of prototype and laboratorial model for long-span cable-stayed bridge

    Science.gov (United States)

    Yang, Ou; Ou, Jinping

    2009-03-01

    Since 2004, Shandong Binzhou Yellow River highway bridge health monitoring (SHM) system has started to operate. Abundance data has been acquired during these years. To make full use of these data, a 1/40 scale laboratorial model has been built based on the design information of Shandong Binzhou Yellow River highway bridge. And a health monitoring system of the laboratorial model, which included loading system, local response monitoring subsystem and global response monitoring subsystem, has been designed and implemented. The dynamic performance of bridge model and prototype has been compared and the error analysis has been provided also. The numeric simulation of cable damage localization utilizing damage location vectors (DLVs) has been demonstrated. And the results indicated that using DLVs to localize the cable damage is feasible and accurate. The goal of these efforts is to utilize the convenience of the laboratorial environment to obtain the structural information in ideal state which is hard to get in field.

  20. INVESTIGATION OF DYNAMIC PARAMETRS OF SPLIT SKEWED BRIDGE SPANS IN CASE OF LOSS OF CONTACT BETWEEN END BEAM AND ITS SUPPORT

    Directory of Open Access Journals (Sweden)

    V.S.Safronov

    2015-02-01

    Full Text Available Statement of the problem. In order to get a valid estimate of risks of fracture during the mainten-ance of simply supported skew slab-and-girder reinforced concrete spans of highway bridges the influence of the supporting skew on the natural frequencies spectrum and the corresponding ei-genmodes in case of changing the design model due to loss of contact between beams and support.Results. Possible loss of contact between one of the marginal beams and its support near the sharp angle during the maintenance of transport facility depending on its type and geometrical parameters is substantiated. Modal and frequency spectrum analysis of spans in case of loss of contact between one of the marginal beams and its support is performed.Conclusions. The analysis revealed possible loss of contact between marginal beams and support, which increases as the skew angle grows and the width and length of the span reduce. A signifi-cant influence of support separation on eigenmodes and frequency spectrum of spans is revealed.

  1. Numerical verification of geometry control method of the construction for super-span cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    Huang Can; Zhao Lei; Bu Yizhi

    2012-01-01

    Taking Sutong Bridge as the object investigated, the correctness of the geometry control method is verified by numerical simulation analysis. Taking the impact of geometric nonlinearity into account, the impacts of structural geo- metric profile induced by temporary loads and temperature field during the construction procedure are investigated. The simulation results indicate that only the stage state of the structure during construction is affected. Satisfied outcome of construction control can be achieved based on ~eometrv control method.

  2. 大跨度连续下承式钢箱拱桥设计%Design of Long-Span Continuous Through Type Steel Box Arch Bridge

    Institute of Scientific and Technical Information of China (English)

    李国普; 李斐然

    2016-01-01

    为满足桥梁的景观和功能要求,小浪底坝后保护区交通桥上部结构采用(95+152+95) m三跨连续下承式钢箱拱结构。主梁为预应力混凝土π形梁,采用钢管桩+贝雷梁法施工。拱肋为钢箱提篮拱,结构用钢采用Q345D钢板,先工厂预制再现场焊接成型。吊索采用7根φ15.2环氧喷涂无粘结钢绞线,缠包后热挤HDPE ,抗拉强度标准值1860 M Pa。下部结构采用柱式台、倒V形实体薄壁墩、高桩承台、钻孔灌注桩基础。采用非线性程序TDV进行计算分析,结果表明,该桥的强度、刚度和稳定性以及抗震性能均满足规范要求。%To meet the landscape and function requirements proposed , the transportation bridge in the conservation area behind the Xiaolangdi Dam adopts a three‐span continuous through type steel box arch bridge structure with span arrangement of (95+152+95) m .The main girder is the prestressed concrete π‐shaped girder ,constructed by the combined use of steel tube piles and bailey truss .T he arch ribs are the steel box basket handle arches .T he predominant material used for the structure is the Q345D steel plate ,and all the components are prefabricated in the factory and transported to the bridge site for welding to take shape .Each hanger consists of 7φ15 .2 epoxy non‐binding steel strands ,extruded with HDPE after wrapping .The hanger has a standard tensile strength of 1 860 MPa .The substructure of the bridge incorporates column‐type abutments ,in‐versed V‐shaped solid thin‐wall piers ,high‐rise pile caps and bored piles .The non‐linear program TDV was used to do calculation .The results of the calculation demonstrate that the strength ,ri‐gidity ,reliability and anti‐seismic performance of the bridge all meet the code requirements .

  3. 两跨连续斜交梁桥振动台试验研究%Shaking table tests for a two-span continuous skew girder bridge

    Institute of Scientific and Technical Information of China (English)

    许永吉; 卓卫东; 孙颖

    2016-01-01

    The dynamic characteristics and three-dimensional seismic response of a two-span continuous skew girder bridge were analyzed,using parameters,such as,skew angle,shear span ratio,reinforcement ratio and axial compression ratio and so on.Taking a skewed girder bridge of Fujian as an engineering example,a 1 ∶5 scale two-span continuous skewed girder bridge model was designed for shaking table tests.Adopting shaking table tests and FE numerical analysis, the seismic responses and damage characteristics of the skewed girder bridge were studied.Results of shaking table tests showed that the structure's acceleration response and displacement response are guite different under different types of ground motion and at the same site or different types of ground motion and at different sites;under the same skew angle. the smaller the axial compression ratio,the larger the acceleration and displacement responses;when the axial compression ratio is the same,the smaller the skew angle,the larger the acceleration and displacement responses;a reasonable choice of skew angle has a great influence on the dynamic performance of skew bridges in the design of skew bridges.%选取了斜交角、配箍率和轴压比等设计参数,对两跨连续斜交梁桥进行结构动力特性分析和单向地震动输入下结构的地震反应分析。以福建省高速公路某座斜交梁桥为工程背景,设计制作了一座1/5缩尺两跨连续混凝土斜交梁桥试验模型,结合振动台模型试验和数值模拟分析,研究斜交梁桥地震响应及震害特点。振动台模型试验结果表明:不同场地类别的地震动及同一场地类别但不同的地震动作用下,结构的加速度响应、位移响应差别较大;在相同斜交角时,轴压比越小,加速度和位移响应越大;当轴压比相同时,斜交角越小,加速度和位移响应越大。从试验可知,在斜交桥设计中,合理选择斜交角对桥梁动力性能有很大的影响。

  4. The Design and Analysis of Long-Span and Low-Depth Prestressed Composite Steel-Concrete Beam Bridge

    Institute of Scientific and Technical Information of China (English)

    张俊平; 黄海云; 黄道沸

    2002-01-01

    The design scheme of long-span and low-depth composite steel-concrete beams is introduced, and the methods of avoiding the cracking of concrete deck in the negative moment regions are proposed. Moreover, significant exploration for problems of the composite beams has been made, such as optimizing construction steps to regulate the stress, applying jacking technique to exert prestress on the concrete deck, investigating the uplifting force principle of the shear connectors by means of model test and non-linear finite element analysis, and pointing out the countermeasure to reduce tension force of the shear connectors.

  5. Influence of rubber buffer devices on collision between a cable-stayed bridge and its approach span%橡胶缓冲装置对斜拉桥及引桥碰撞影响研究

    Institute of Scientific and Technical Information of China (English)

    张文学; 吴海军; 陈士通

    2013-01-01

    针对大跨度斜拉桥与引桥之间碰撞研究不深入、对斜拉桥与引桥之间防碰撞措施研究不系统等问题,研究橡胶缓冲装置对斜拉桥与引桥之间碰撞响应的减震效果,分析橡胶缓冲装置结构参数对斜拉桥与引桥之间碰撞响应的影响规律.%The seismic behavior study of cable-stayed bridges at home and abroad is relatively perfect, and abundant achievements have been obtained. The aseismic performance of a cable-stayed bridge ordinarily can meet aseismic requirements, but cable-stayed bridge expansion joint damages and approach bridge beam collapses often happens under earthquakes. The study on the collision between a cable-stayed bridge and its approach span is not deep, and the anti-collision measures study is not systematical. Here, the shock absorption effect of rubber buffer devices on impact responses between a cable-stayed bridge and its approach span was investigated. The influence law of rubber buffer devices structural parameters on impact responses between a cable-stayed bridge and its approach span was analyzed in detail.

  6. 关于大跨径连续刚构桥中跨合拢时常见问题的效应验算%The Effect Check of Problems in Closing the Middle Span of Long-Span Continuous Rigid-Frame Bridge

    Institute of Scientific and Technical Information of China (English)

    王洁

    2014-01-01

    The rationality of the force and smoothly of linearity which are high pier and long span continu‐ous rigid-frame bridge to its structure are the control points during the construction of bridge .In order to neglect the structural system of bridge under construction not follow the construction order during the con‐struction of long span bridge .T hese problems usually neglected by the field technical managers ,and these neg‐lected problems can influence the stress of long span rigid frame bridge before closing the span .%高墩大跨径的连续刚构桥对其结构受力的合理性及线性的平顺,成为施工过程中的控制重点。在大跨径桥梁施工过程中常常忽视在建桥梁的结构体系,而没有严格按照施工顺序进行施工。这些常被现场技术管理人员所忽略的问题,通常会影响到大跨径刚构桥在最终合拢前的受力。

  7. A型高墩大跨混凝土连续刚构桥地震反应影响分析%Impact Analysis of Seismic Response A Type High Pier and Long Span Concrete Continuous Rigid Frame Bridge

    Institute of Scientific and Technical Information of China (English)

    陈思孝; 夏修身; 李锐

    2014-01-01

    Remarkable characteristics of A type high pier and long span concrete continuous rigid frame bridge are high pier, larye span, massive girder and pier. This paper analyzes the influence of P-delta effect, the traveling wave effect on the A type high pier and long-span continuous rigid frame bridge seismic response of concrete and elastic plastic re-sponse characteristics of earthquake, it also discusses the seismic ductility design method of A type high pier and long span concrete continuous rigid frame bridge. The results showed that: A type continuous rigid frame bridge with high piers on seismic design limited ductility is reasonable, P-delta has little effect on type A high pier and long-span continu-ous rigid frame bridge’s response in earthquake, which cauld be ignared in design; traveling wave effect on the A type high pier and long-span continuous rigid frame bridge response earthquake should be combined with a specific type of bridge and bridge site selection. Reasonable seismic wave velocity and proper travelling wave speed should be selected in analysis. The research could sexve as a reference for high pier and long-span Railway Bridge design.%A型高墩大跨混凝土连续刚构桥的显著特点是墩高、跨度大、梁体及墩身质量巨大。文章分析了P-Δ效应、行波效应对A型高墩大跨混凝土连续刚构桥地震反应的影响及弹塑性地震反应特点,探讨了A型高墩大跨混凝土连续刚构桥的延性抗震设计方法。结果表明: A型高墩连续刚构桥按有限延性的抗震设计比较合理,P-Δ效应对A型高墩大跨连续刚构桥地震反应的影响较小,设计中可以忽略;行波效应对A型高墩大跨连续刚构桥地震反应的影响应结合具体的桥型、桥址场地类别,选取合理的地震动、恰当的行波速度进行分析。

  8. A dimer of bis(N-heterocyclic carbenerhodium(I centres spanned by a dibenzo-18-crown-6 bridge from synchrotron radiation

    Directory of Open Access Journals (Sweden)

    Stephen B. Colbran

    2013-01-01

    Full Text Available The compound (μ-3,3′,3′′,3′′′-{[2,5,8,15,18,21-hexaoxatricyclo[20.4.0.09,14]hexacosa-1(22,9,11,13,23,25-hexaene-11,12,24,25-tetrayl]tetrakis(methylene}tetrakis(1-methyl-1H-imidazol-2-ylbis[(η4-cycloocta-1,4-dienerhodium(I] bis(hexafluoridophosphate acetonitrile sesquisolvate dihydrate, [Rh2(C8H122(C40H42N8O6](PF62·1.5CH3CN·2H2O, crystallized from acetonitrile under an atmosphere of diethyl ether. In the crystal structure, the complex cation exhibits two square-planar RhI centres, each bound by a cyclooctadiene (COD ligand and by two adjacent imidazolylidene N-heterocyclic carbene (NHC donors from the same phenoxy ring of the {[dibenzo-18-crown-6-11,12,24,25-tetrayl]tetrakis(methylene}tetrakis(1-methyl-1H-imidazol-2-yl (L ligand. The dibenzo-crown ether bridge of L spans the Rh centres and forms hydrogen bonds with water molecules. One water molecule with half occupancy bridges adjacent macrocycles in the lattice. Another water with full occupancy forms weak hydrogen bonds to the crown ether O atoms and is, in turn, part hydrogen bonded by a lattice water with half occupancy. The latter water is within hydrogen-bonding distance of a fourth water also with partial occupancy. The result of these interactions is the formation of a layer in the ab plane. Two PF6− ions, one of which is twofold disordered, and one ordered and one twofold disordered (with 0.5 occupancy lattice acetonitrile molecules complete the crystal structure.

  9. 大跨径梁桥长期挠度的控制技术研究%Control Technology of Long-term Deflection for Long-span Girder Bridge

    Institute of Scientific and Technical Information of China (English)

    黄新哲

    2011-01-01

    This paper analyzed the development of large-span girder bridge, based on the problems of long-term deflection in large-span girder bridge, put forward the causes of long-term deflection and control measures by an example of a bridge, to provide reference for the relevant project officers.%文章就大跨梁桥发展概况进行了剖析,针对大跨梁桥长期挠度的问题现象,以某大桥为例提出了长期挠度成因及控制措施新途径,以供相关工程人员参考.

  10. TECHNICAL CHALLENGES AND REFINEMENT RESEARCH ON WIND RESISTANCE OF LONG-SPAN BRIDGES%大跨度桥梁抗风的技术挑战与精细化研究

    Institute of Scientific and Technical Information of China (English)

    葛耀君

    2011-01-01

    With the rapid development of long span bridges in China in past three decades, this paper presented technical challenges of wind resistance on three type long-span bridges, including flutter instability and control of suspension bridges, wind induced vibration of cable stayed bridges and control of wind-rain induced cable vibration, vortex induced vibration and control of arch bridges, and the refinements on aerodynamic flutter and buffeting of super long span bridges. It can be concluded that the intrinsic limit of a span length due to aerodynamic stability is about 1,500m for suspension bridges, and beyond or even approaching this limit, designers should be prepared to improve its aerodynamic stability. The cable-stayed bridges with a main span over 1000m have high enough critical flutter speed, but the main aerodynamic concern is the rain-wind induced vibration of long stay cables. Except one example of vortex-induced vibration, long-span arch bridges have no wind resistance problem. The refinement research on wind resistance of long-span bridges was also introduced with a full-mode flutter analysis method, the bridge buffeting frequency-domain analysis under skew wind action, the bridge flutter and buffeting reliability evaluation method based on second order theory and first passage theory, and the unveiling of a bridge flutter evolution process, generation mechanism and control law.%以我国30年大跨度桥梁的快速发展为研究背景,对三种大跨度桥梁的抗风技术挑战进行了分析,着重探讨了悬索桥的颤振性能及其控制、斜拉桥风振性能与拉索风雨振和拱式桥涡激共振及其控制,并提出了特大桥梁风振精细化理论和方法.研究结果表明:悬索桥的颤振稳定性跨径上限约为1500 m,超过甚至接近这一上限时,必须采取措施改善加劲梁的抗风稳定性;千米级大跨度斜拉桥仍具有足够高的颤振临界风速,其主要抗风问题是长拉索的风雨振动;大跨

  11. Parameters analysis for assistant cables of system for transient main cable and catwalk of long-span suspension bridges at construction stages

    Science.gov (United States)

    Li, Shengli; Ou, Jinping

    2009-03-01

    On the basis of static, dynamic and transient analysis for the prestressing cable structures, the parameters to control the vibration of the system for transient main cables and catwalk of some long-span suspension bridge at the construction stages with the assistant cables are investigated adopting the method of the finite element considering the geometry nonlinearity. The review and prospect to control vibration with assistant cables are summarized, the finite element modeling of the system for transient main cables and catwalk is established, and the influence of the position of the assistant cables, disposed fashion and the tensile forces upon the critical frequencies of the system for transient main cables and catwalk is researched. At the same time, the effect of the damp and the tensile forces of the assistant cables on the equivalent damping ratio of the system for transient main cables and catwalk inside and outside the plane is studied and the effect to control the vibration of the system is analysed. In the end, the influence of the transformation for the tensile forces about assistant cables upon those of the transient main cables and catwalk is also investigated. Results show that, to increase the critical frequencies of the system, the assistant cables should be laid vertically with the main cables and be located in interim span or between the tower and interim span, and to increase the amount of the assistant cables can increase the critical frequencies ,and to increase the rigidities of the assistant cables can improve the ones of the transient main cables but decrease the anti-torsion ability of the catwalks, and to increase the damp of the assistant cables can improve the vibration of the transient main cables inside and outside the plane but the result is little outside the plane, and in addition the effect of the rigidities of the assistant cables is larger outside the plane but is little inside the plane. The results also show that the

  12. Research of the aerostatic and aerodynamic stability of super long-span cable-stayed bridges%超大跨度斜拉桥空气静力和动力稳定性研究

    Institute of Scientific and Technical Information of China (English)

    张新军; 孙海凌

    2014-01-01

    With the increase of span length,the cable-stayed bridge tends to be a more slen-der structural system,and consequently the wind stability becomes an important problem for its design and construction. Three-dimensional nonlinear aerostatic and aerodynamic stability anal-ysis of long-span bridges is used to investigate the aerostatic and aerodynamic stability of a su-per long-span cable-stayed bridge with main span of 1 400 m,and the results are compared with those of a suspension bridge with the similar main span,and considering from the aspect of wind stability,the availability of using the cable-stayed bridge in super long-span bridges whose main span exceeds 1 000 m is discussed. In addition,parametric analysis on the aerostat-ic and aerodynamic stability of super long-span cable-stayed bridges is conducted including the depth and width of the girder,structure style of the tower,the tower’s height-to-span ratio,the ratio of side span to main span,the auxiliary piers in the side span and the anchorage system of stay cables etc,and the key design parameters are pointed out,and also their reasonable values are proposed. The results show that as compared to the suspension bridge with the same main span,the cable-stayed bridge has greater structural stiffness,and becomes more stable under the static and dynamic wind action,and consequently becomes a favorable structural system for super long-span bridges whose main span exceeds 1 000 m;the super long-span cable-stayed bridge becomes more aerostatically and aerodynamically stable under the cases that the girder depth is increased,the girder width is decreased,the inverse Y-shaped tower is used,the tow-er’s height is increased,the side span is shortened,the auxiliary piers are installed in side span and the stayed cables are partially earth-anchored.%随着斜拉桥跨度的持续增长,结构更趋于轻柔,风作用下的结构稳定性已成为超千米主跨斜拉桥设计和研究的重要问题。采用

  13. Design of Cofferdam for Non-Navigable Span Bridge of Hong Kong-Zhuhai-Macau Bridge over Shallow Water Area%港珠澳大桥浅水区非通航孔桥围堰设计

    Institute of Scientific and Technical Information of China (English)

    黄剑锋

    2015-01-01

    The non‐navigable span bridge of the Hong Kong‐Zhuhai‐Macao Bridge over the shallow water area is a 85‐m span continuous composite girder structure ,the foundations for the bridge are the steel pipe composite pile foundations and the pile caps and piers supported on the foundations are the precast structures .The foundations were constructed by the interlocked doub‐le‐wall steel boxed cofferdams with no internal bracings .A cofferdam is 17 .6 m long ,13 .4 m wide ,23 .2 m high and the thickness of the bulkhead of the cofferdam is 0 .75 m .The cofferdam was designed into a removable structure and in plan ,was divided into 8 segments which were inter‐connected by the combination way of tenon locks and bolts .The cofferdam is mainly made up of three parts of the lateral plates ,horizontal ring plates and vertical partition plates and joints .In accordance with the different force conditions of the cofferdam in the construction process ,4 load cases were considered in the design .The software MIDAS Civil 2006 and ANSYS were used to set up the finite element models for the different load cases and the displacement and stress of the cof‐ferdam and its base sealing structure were analyzed .The results of the analysis indicate that the values of the maximum displacement and stress of the cofferdam and the base sealing concrete structure under the different load cases are all less than those as specified in the codes and can meet the requirements ,proving that the force conditions of the cofferdam in the construction are safe and the cofferdam is structurally rational .%港珠澳大桥浅水区非通航孔桥为跨度85 m的连续组合梁结构,其基础采用钢管复合桩基和预制墩台结构,基础采用无内支撑结构的双壁锁口钢套箱围堰施工。围堰长17.6 m、宽13.4m、高23.2m,壁仓厚0.75m。围堰设计成可拆装式结构,平面分为8块,各分块之间采用榫头式锁口与螺栓组合的方式连接。

  14. 基于 TMD 的多跨折形人行吊桥的振动控制研究%Research on vibration control of multi-span zigzag-shaped pedestrian suspension bridge based on TMD

    Institute of Scientific and Technical Information of China (English)

    刘礼昕; 盛宏玉

    2015-01-01

    文章建立了多跨折形钢结构人行吊桥模型,通过有限元软件 ANSYS进行模态分析和人行荷载作用下的动力时程分析。结果表明,该桥在人行荷载作用下振动响应过大,影响结构的正常使用。在吊桥的跨中位置安装调频质量阻尼器(tuned mass damper ,TMD)进行减振控制,通过计算选取最优的 TMD参数。对比相同人行荷载作用下安装TMD装置和未安装TMD装置桥梁的动力响应,结果表明 TMD能有效减轻吊桥的振动响应。%In this paper ,a model of multi‐span zigzag‐shaped pedestrian suspension bridge made of steel material is set up .The modal analysis and dynamic time‐history analysis under the pedestrian loads are presented by using the finite element software ANSYS .The results show that the vibration re‐sponse of the bridge under the pedestrian loads is too big and will influence the functions of the struc‐ture .To control the vibration level ,the tuned mass dampers(TMD) are installed on mid‐span of the suspension bridge by selecting optimal TMD parameters based on calculation .The vibration responses of the bridge with and without TMD device under the same pedestrian loads are calculated and com‐pared .The results show that TMD can reduce the vibration response of the suspension bridge effec‐tively .

  15. 国内大跨径悬索桥锚碇锚固系统比较研究%The Compare and Investigation of Anchor System for Anchorage of Domestic Long-Span Suspension Bridge

    Institute of Scientific and Technical Information of China (English)

    李海; 鲜亮; 姚志安

    2011-01-01

    The anchor system for anchorage of suspension bridge plays an important controlling role in overall safety of structure . The paper mainly compares the different anchor system for anchorage of domestic long-span suspension bridge, and Makes an investigation on durability 、reliability and economy, which can be used for reference on adoption for future anchor system for anchorage of long-span suspension bridge.%悬索桥锚碇锚固系统在保证结构整体安全上具有重要控制作用.主要对我国目前大跨径悬索桥锚固系统不同体系作了比较,并对各种体系的耐久性、可靠性及经济性等方面进行了研究,为今后大跨径悬索桥锚固系统体系的采用提供了借鉴.

  16. Simulation Study on Train-Induced Vibration Control of a Long-Span Steel Truss Girder Bridge by Tuned Mass Dampers

    Directory of Open Access Journals (Sweden)

    Hao Wang

    2014-01-01

    Full Text Available Train-induced vibration of steel truss bridges is one of the key issues in bridge engineering. This paper talks about the application of tuned mass damper (TMD on the vibration control of a steel truss bridge subjected to dynamic train loads. The Nanjing Yangtze River Bridge (NYRB is taken as the research object and a recorded typical train load is included in this study. With dynamic finite element (FE method, the real-time dynamic responses of NYRB are analyzed based on a simplified train-bridge time-varying system. Thereinto, two cases including single train moving at one side and two trains moving oppositely are specifically investigated. According to the dynamic characteristics and dynamic responses of NYRB, the fourth vertical bending mode is selected as the control target and the parameter sensitivity analysis on vibration control efficiency with TMD is conducted. Using the first-order optimization method, the optimal parameters of TMD are then acquired with the control efficiency of TMD, the static displacement of Midspan, expenditure of TMDs, and manufacture difficulty of the damper considered. Results obtained in this study can provide references for the vibration control of steel truss bridges.

  17. 大跨度桥式起重机平衡台车开裂原因分析%Cracking Analysis for Load Dividing Dolly of Long-span Bridge Type Crane

    Institute of Scientific and Technical Information of China (English)

    陈驰中; 罗会信

    2011-01-01

    Bridge Type Crane is widely applied hoisting and conveying machine in the manufacturingenterprise. Cracks were found on the load dividing dolly of a long-span bridge type Crane. Bymaking nondestructive inspection and dynamic stress testing on dolly, the causes of cracks on loaddividing dolly were analyzed, that provided the basic reference for the crane's later strengtheningproject.%桥式起重机是生产企业中应用非常普遍的一种起重运输机械.在大跨度桥式起重机的平衡台车上发现裂纹.通过对起重机平衡台车进行无损探伤以及动载应力测试,分析造成平衡台车裂纹产生的力学原因,为其提供了后期加固方案的依据.

  18. Research on Construction Technology for No. 0 Section of Four-track Long Span Rigid Frame Bridge%四线大跨度刚构桥0号段施工技术研究

    Institute of Scientific and Technical Information of China (English)

    李瑞俊

    2015-01-01

    刚构桥梁中0号段作为悬臂梁施工的起点,在悬臂施工、运营中是应力最集中、应力变化最复杂的梁节段,其施工质量控制全桥质量,也影响梁体后期使用运营。文章结合目前国内四线铁路单T最大跨度刚构桥,系统研究了大跨度刚构桥“长、高、大”0号段模板、托架设计与施工、混凝土浇筑工艺、线形与应力监测分析,解决“长大”0号段施工中难题,取得的施工技术成果值得同类工程借鉴。%No. 0 section of rigid frame bridge, as the starting point of cantilever beam construction, is of the most con-centrated stress and the most complex stress variation in the cantilever construction and operation, its construction quality controls the full bridge quality, it also affects the post operation of beam body. Combined with the current four-track sin-gle T rigid frame railway bridge with maximum span in China, formwork, design and construction of bracket, concrete pouring process, linear and stress monitoring analysis of long, high, large No. 0 section of long-span rigid frame bridge are systematically studied, the problems during construction of long and large No. 0 section are resolved,the achieve-ments of construction technology can provide reference for similar engineering.

  19. Temperature profiles from MBT casts from the MACKINAC from Ocean Weather Station B (OWS-B) in the North Atlantic Ocean from 26 July 1966 to 23 August 1966 (NODC Accession 6600312)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Bathythermograph data were collected from the MACKINAC within a 1-mile radius of Ocean Weather Station B (56305N 05100W) and in transit. Data were collected by the...

  20. Aerodynamic stability study of a long-span prestressed concrete cable-stayed bridge. Aerodynamic behavior of edge box girder under uniform flow; Chodai PC shachokyo no taifu anteisei ni kansuru kenkyu. Ichiyoryuchu ni okeru edge girder keishiki no kuriki tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, T. [Obayashi Corp., Tokyo (Japan)

    1999-01-10

    In recent years, the construction of long-span bridges is on the increase. Prestressed concrete cable-stayed bridges are dynamically very efficient structures of relatively low cost that blend in well with the landscape. Maintenance is also easy. Consequently, the adoption of edge box girders for cable-stayed bridges is increasing worldwide, but problems related to the aerodynamic stability of the structure have emerged. The aerodynamic stability of edge box girders for a prestressed concrete cable-stayed bridge was investigated under uniform flow conditions by conducting several wind tunnel experiments. As a result, the section of the bridge deck was optimized to prevent torsional flutter within an angle of attack varying from -5 to +5 degrees. It is therefore possible to guarantee the aerodynamic stability of long-span prestressed concrete cable-stayed bridges. (author)

  1. Assessment of vehicular live load and load factors for design of short-span bridges according to the new Egyptian Code

    Directory of Open Access Journals (Sweden)

    Hatem M. Seliem

    2015-04-01

    The study shows that concrete box-girders designed according to ECP-201:2012 and ECP-201:2003 using the ultimate limit state method yield almost the same demand. Despite the increase in the VLL of ECP-201:2012, and consequently the live load forces, concrete I-shaped girder bridges will be subjected to less total factored internal forces in comparison to ECP-201:2003 This is attributed to the interaction between the live to dead loads ratio and the load combinations. Design of composite steel plate girder bridges according to ECP-201:2012 using the allowable stress design method yields over designed sections.

  2. 低速风洞全模TPS试验空气桥的设计与优化%Design and optimization of the air bridge for low speed full-span TPS test

    Institute of Scientific and Technical Information of China (English)

    章荣平; 王勋年; 黄勇; 冯治

    2012-01-01

    TPS(Turbofan Powered Simulator)technology is the most advanced engine simulation in wind tunnel test. The air bridge is a key technology of TPS tests. This paper presents the design of the air bridge for low speed full-span TPS test. Optimum designs are made for the key beams of the air bridge by using FEM (finite-element method). Layout and the dimension of bellows are also optimized. According to the computation results, the key law of air bridge design is concluded. The air bridge is finally designed according to the space of the model, the inside e-quipments and the requirement of the TPS test. The final design has little effect on force measurement and has little pressure and temperature effect. The success in low speed full-span TPS test indicates that the air bridge meet the requirement of TPS test.%TPS试验技术是目前风洞试验中最先进的涡扇发动机模拟技术,空气桥是TPS试验技术的关键技术之一.介绍了低速全模TPS试验空气桥的设计.通过有限元数值模拟对空气桥关键受力梁进行了优化设计,并进一步对空气桥进行了整体优化,掌握了关键参数影响空气桥性能的规律.综合考虑模型内部空间、内部设备及空气桥的技术要求,完成了空气桥的设计,优化后空气桥对天平测力的影响较小,且同时具有较好的克服高压空气的内力、温度效应的能力.试验结果表明,空气桥性能满足TPS试验的要求.

  3. Boundary Spanning

    DEFF Research Database (Denmark)

    Zølner, Mette

    The paper explores how locals span boundaries between corporate and local levels. The aim is to better comprehend potentialities and challenges when MNCs draws on locals’ culture specific knowledge. The study is based on an in-depth, interpretive case study of boundary spanning by local actors in...... approach with pattern matching is a way to shed light on the tacit local knowledge that organizational actors cannot articulate and that an exclusively inductive research is not likely to unveil....

  4. 大跨桥梁健康监测系统设计构成及其进展%Designed Components and Development of Health Monitoring Systems for Long Span Bridges

    Institute of Scientific and Technical Information of China (English)

    王戒躁; 钟继卫; 王波

    2009-01-01

    With the constant construction of the new types of long span, lightweight and flexible structure bridges, the safety and durability of the bridges in operation state have attracted great concern from engineering circle and the real-time structural health monitoring and the near real-time structural safety evaluation of the bridges have also become the hot research subjects in the engineering and academic circles. The contents and components of the monitoring and evaluation systems are presented herewith, the current research of the monitoring and evaluation systems for some major bridges at home and abroad are reviewed, the state-of-the-art, development tendency and prospecting of the monitoring system and evaluation items are described and the research findings of the monitoring system for Wuhan Yangluo Changjiang River Bridge are particularly analyzed.%随着大跨、轻、柔等新型桥型的不断建造,桥梁结构运营状态的安全性及耐久性受到工程界高度重视.大跨度桥梁的实时结构健康监测和近实时结构安全评估工作也成为工程界及学术界研究的热点问题.介绍桥梁健康监测与评估系统的内容及系统构成,简要回顾国内外大型桥梁健康监测与评估系统的研究现状,阐述桥梁健康监测与评估项目的发展现状、趋势及前景,并重点分析武汉阳逻长江大桥健康监测系统的研究成果.

  5. Cable Supported Bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    Cable supported bridges in the form of suspension bridges and cable-stayed bridges are distinguished by their ability to overcome large spans.The book concentrates on the synthesis of cable supported bridges, covering both design and construction aspects. The analytical part covers simple methods...

  6. Behaviors of super-long span prestressed cable-stayed bridge with CFRP cables and UHPC girder%CFRP拉索预应力超高性能混凝土斜拉桥力学性能分析

    Institute of Scientific and Technical Information of China (English)

    方志; 任亮; 凡凤红

    2012-01-01

    To discuss the applicability of carbon fiber reinforced polymer (CFRP) cables and reactive powder concrete ( RPC) in super-long span cable-stayed bridges, taking a 1 008 m cable-stayed bridge using steel girder and steel cables as example, a cable-stayed bridge with the same span using RPC (reactive powder concrete) as the girder and advanced composite material CFRP (carbon fiber reinforced polymer) as the cable was designed, in which the cable cross section was determined by the principles of equivalent cable strength and the beam cross section was determined considering the stiffness, shear capacity and local stability. Based on the method of finite element analysis, the comparative study of these two structures on their static properties, dynamic properties, stability and wind resistance were carried out. The results show that it is feasible for using RPC as the girder and CFRP as the cable so as to form a highly efficient, durable cable-stayed bridge of concrete structure and make its applicable span reach about 1 000 m long.%为了探讨碳纤维复合材料(carbon fiber reinforced polymer,CFRP)和超高性能活性粉末混凝土(reactive powder concrete,RPC)在超大跨度斜拉桥中应用的可行性,以主跨1008m的大跨度钢主梁斜拉桥设计方案为例,采用拉索的等强度原则将原桥钢索替换成CFRP索,考虑截面刚度、截面应力和局部稳定等要求,将原桥钢主梁替换成RPC主梁,拟订了一座等跨度的CFRP拉索、RPC主梁斜拉桥方案.采用有限元法分别对两种方案结构的静力特性、动力特性、稳定性能以及抗风性能等进行了分析与比较.结果表明:从结构受力性能角度而言,采用超高性能混凝土主梁和CFRP拉索构成千米级跨度混凝土斜拉桥的结构体系是可行的.

  7. Analysis of Common Aerodynamic Measures for Wind Resistant Design of Long Span Bridges%大跨度桥梁抗风设计常用气动措施分析

    Institute of Scientific and Technical Information of China (English)

    胡长灿; 詹昊

    2015-01-01

    为提高大跨度桥梁的抗风性能,对该类桥梁抑制涡激共振和提高颤振稳定性的常用气动措施及其机理进行初步分析。桥梁涡激共振和颤振稳定性与旋涡的产生和漂移有关,因此气动优化的一般原则是改善结构迎风面和背风面的气动外形以延缓或避免流动分离、减小分离涡尺度、阻碍旋涡漂移路径。抑制桥梁涡激振动一般采用设置倒角、安装风嘴和优化风嘴形状、安装导流板等气动措施;提高桥梁颤振稳定性一般采用安装风嘴和优化风嘴形状、安装稳定板和气动翼板等气动措施。研究表明采用气动措施后,大跨度桥梁的气动性能得到改善。%To improve the wind resistant performance of long span bridges ,the common aero‐dynamic measures and their mechanism for suppressing the vortex‐induced resonance and for im‐proving the flutter stability of the bridges are preliminarily analyzed .Since the vortex‐induced res‐onance and flutter stability of the bridges are correlated with the vortex generation and vortex drift ,the general principle of optimizing the aerodynamic measures is to improve the windward and leeward structural aerodynamic profiles in order to delay or avoid the flow separation ,reduce the separated vortex scales and impede the vortex drift paths .As regards the aerodynamic measures for suppressing the vortex‐induced vibration of the bridges ,the rounded corners and wind fairings are generally installed ,the shapes of the wind fairings are optimized and the guide vanes are in‐stalled while as regards the measures for improving the flutter stability ,the wind fairings are gen‐erally installed ,the shapes of the wind fairings are optimized and the stabilizers and aerodynamic wing plates are installed .Researches indicate that the aerodynamic performance of the long span bridges can be improved after these measures have been taken .

  8. 高墩大跨连续刚构桥的稳定性分析%Analysis of Stability of Long-span Continuous Rigid Frame Bridge with High Pier

    Institute of Scientific and Technical Information of China (English)

    王菲; 田山坡; 禚一

    2012-01-01

    Research purposes: The highway in western China or the remote region needs to cross over rivers and valleys and passes the regions with complex terrains due to the limitation of topographical condition . For this reason, the long -span continuous rigid frame bridge with high pier becomes more and more and the height of the bridge increases from several decameters to hundreds of meters. With increases of the pier height and the span length, the research on the stability of such kind of bridge is becoming more and more important. Research conclusions:Taking the long - span continuous rigid frame bridge with(90 + 168+90) m high pier in Shanxi province as the engineering background, the basic principle related to the structure stability is discussed and the stability of the high pier, the stability of the longest cantilever during construction and the stability in complete stage of the bridge are analyzed. From the calculation results it can be seen that for the bridge presented in this paper, the temperature effect has a little influence on the high pier stability, the wind load along the bridge axial direction has the most negative impact on the structure stability in the construction stage of the longest cantilever, and during the complete stage of the bridge, the lane load and the load of the crowded people set on the middle span has the most negative impact on the bridge stability. Furthermore, wind has a little influence and the influence of the temperature effect can be ignored in this stage. The calculation results also show this bridge has a good stability during its construction process and in the complete stage of bridge. The calculation and analysis processes presented in this paper can provide the reference to the similar works.%研究目的:西部地区及偏远地区受地形条件的限制,修建公路时常需要跨越河流、沟谷等复杂地形,因此高墩大跨连续刚沟桥的修建日益增多,其墩高也由原来的几十米提

  9. 地震作用下中等跨径RC连续梁桥系统易损性研究%Study on system vulnerability of medium span reinforced concrete continuous girder bridge under earthquake excitation

    Institute of Scientific and Technical Information of China (English)

    李立峰; 吴文朋; 黄佳梅; 王连华

    2012-01-01

    Medium span multi-span continuous RC bridges,whose main failure modes are reflected in piers,abutments or bearings,are widely used in China.One common continuous girder bridge is taken as the analytical model;uncertainties in the strength of material and the weight of superstructure are considered,then a set of 10 nominally identical but statistically different bridge samples are developed for the bridge using the Latin hypercube sampling technique.100 earthquake records are chosen from PEER according to the site condition of bridge to account for the uncertainty of ground motions,and then combined randomly with 10 bridge samples.Then,a series of nonlinear time-history analyses are conducted to obtain the responses of structure,and four limit states for different components are defined.vunerability curves of piers,abutments and bearings are obtained utilizing the traditional reliability and probability tools,and furthermore the system vulnerability of structure is studied using the joint failure probability method.The results show that the bearings,especially the active bearing of abutment,are more vulnerable than the column piers and the abutments.The failure probability of bridge system,which is calculated using the first-order and the second-order reliability principles,is larger than those of structural members,indicating that it is more reasonable to assess the seismic behavior of bridge basing on the system vulnerability.%中等跨径混凝土连续梁桥是一种广泛应用的桥梁结构形式,地震作用下该类桥梁的破坏主要体现在桥墩、桥台和支座位置。以一典型多跨连续梁桥为例,考虑材料强度和上部结构容重等不确定性因素的影响,运用拉丁超立方抽样方法建立了10个桥梁样本。根据场地类型从PEER强震数据库中选取100条地震波来模拟地震动的不确定性,并与10个桥梁样本随机组合。对结构进行非线性时程分析后得到结构的响应,并分别定义了

  10. Fasting style collapse of a multi-span arch bridge analyze the causes of the box%某多跨空腹式箱形拱桥倒塌成因分析

    Institute of Scientific and Technical Information of China (English)

    饶奇志; 易汉斌; 俞博

    2014-01-01

    In this paper, a box-shaped multi-span arch bridge collapsed fasting accident, for example, ana-lyze the causes of its collapse. First, the bridge collapse accident scene investigation, proved a bit of geologi-cal bridge pier foundation and Conditions; secondly, according to the findings of the arch structure was seized count;moreover, considering the effect of cutting down on the pile bearing capacity of the river bed;the results show that under the riverbed leads to the bridge substructure cut transition from low pile platform for high pile caps, this time the stakes withstand compressive stress is greater than its carrying capacity, the stakes can not bear the weight of the upper structure, leading to the occurrence of arch collapsed.%本文以某多跨空腹式箱形拱桥倒塌事故为例,对其倒塌成因进行了分析。首先,对桥梁倒塌事故现场进行了调查,探明了桥墩基础及桥位地质条件情况;其次,根据调查结果对拱桥结构进行了检算;此外,考虑了河床下切对桩基承载力的影响;分析结果表明,河床下切导致该桥下部结构从低桩承台转变为高桩承台,此时木桩承受的压应力大于其承载能力,木桩已经不能承担上部结构自重的作用,导致拱桥发生倒塌。

  11. Multi-mode coupled flutter numerical simulation for TMD control of long-span bridges%大跨度桥梁多模态耦合颤振的TMD控制

    Institute of Scientific and Technical Information of China (English)

    张鸣祥; 王建国; 汪权

    2012-01-01

    This study addresses the methodology and parameter study of TMD control for long-span bridges. The differential equations governing the motion of the structure with TMDs are established in the mode space, in which the effects of aerodynamic self-excited force are taken into account. The revised automatic analysis for multimode-coupled flutter,which is the single parameter searching method with- out iterations,is adapted for the flutter control analysis of structure-TMDs system based on the complex modal theory. Taking a three-tower suspension bridge being built crossing the Yangtze River for a nu- merical example,the flutter analysis of the original bridge and flutter control analysis of bridge-TMDs system are performed. The TMD parameters are discussed for influence of critical wind speed.%推导了装有TMD的结构在气动自激力作用下的动力微分方程,基于模态空间中多模态耦合颤振分析手段,运用考虑安装TMD的多模态自动分析法对结构-TMD系统进行了颤振分析和TMD控制分析,使多模态自动分析法能适用于TMD颤振控制分析,避免了双参数搜索和迭代计算,提高了计算效率。对某在建三塔悬索桥进行了原结构颤振分析和TMD-结构颤振频域分析,探讨TMD控制参数对颤振临界风速的影响。

  12. Safety distance for bearing members of long-span suspension bridge in highway fire%大跨径悬索桥承重构件公路火灾安全距离研究

    Institute of Scientific and Technical Information of China (English)

    李利军; 董晓明; 胡兆同

    2014-01-01

    In order to study the influence of highway fire on long-span suspension bridges and fill in the blank of suspension bridge fire research, combining structure fire analysis, an indirect coupling method was chosen to carry out the thermal-structure coupling analysis. Taking a 300 MW vehicle fire as an example, ANSYS was used to build the fire coordinate model of different section of a typi-cal suspension bridge. On the basis of fire research domestic and abroad, basing on the Ingason H. square growth model and taking the safety distance for cable bearing component of the long-span sus-pension bridge in highway fire as a research object, a numerical simulation for the safety distance of suspender cable and main cable was performed to reduce project risk and ensure the safety and sta-bility of the bridge. A thermal release rate mathematical model which suits highway fire study was put forward; The safety distance model in highway fire was established, and the size of combustion heat source and heat release rate of unit area were determined; With the thermal-structure coupling analysis, the fire safety distance for suspender cable and main cable of different diameters (0. 4 ~1. 0 m) were determined. The research results can provide some scientific basis for the fire resist-ance design of long-span suspension bridges.%为研究公路火灾对大跨径悬索桥带来的影响,弥补悬索桥火灾研究的空白,结合结构火灾分析的特点,确定选择间接耦合法进行热-结构耦合分析。以300 MW 车辆火灾为例,运用 ANSYS 有限元程序,建立了悬索桥不同断面的火灾坐标模型,在总结国内外火灾研究工作的基础上,基于 Ingason H.平方增长模型,以典型的大跨径悬索桥缆索承重构件的公路火灾安全距离为研究对象,以降低工程风险、保证大跨径悬索桥结构的安全性和稳定性为研究目标,对大跨径悬索桥吊索和主缆安全距离进行数值模拟,提出

  13. Fragility analysis of long span continuous rigid frame bridge under multi-support excitations%多点地震激励下大跨连续钢构桥易损性分析

    Institute of Scientific and Technical Information of China (English)

    李吉涛; 杨庆山; 刘阳冰

    2013-01-01

    Due to wave passage effect, incoherence effect, local effect and other factors in seismic ground motion, the internal force and deformation of long span continuous rigid framed bridges will be error-estimated when seismic responses analysis is performed under identical support ground motion excitations. A Monte Carlo simulation method was used to establish the random sample for the system of large-span continuous rigid frame bridge under ground motion excitation, by means of considering the uncertainties of structural material and ground motion, both for identical support ground motion excitations and multiple support ground motion excitations. The ductility ratio of piers was defined as the index of damage state of the bridge. The seismic fragility analysis was carried out under the two different modes of excitations and the fragility curves of the bridge were given based on the damage state definition. The peak acceleration relationship between the two different modes of excitations was obtained under the same level damage.%针对地震动存在行波效应、场地效应、不相干效应等因素,分析大跨连续钢构桥在一致地震激励输入响应时结构内力和变形会被偏估问题,考虑结构及地震动不确定性,采用蒙特卡罗方法建立一致激励与多点激励两种工况下大跨连续钢构桥-地震动系统随机样本.以桥墩位移延性比表示桥梁破坏状态阶段,对桥梁易损性进行分析,给出大跨连续钢构桥结构的易损性曲线,得到同样程度破坏的多点地震激励与一致地震激励下加速度峰值关系.

  14. Steel Spans,

    Science.gov (United States)

    1984-01-31

    Trifle, in an instant I will walk ! Moonlight silvered the rails. After the station the route/path went along the dark/nonluminous malodorous swamp... silver . How is it best to approach the fragments of bridge? - ~Hitlerites for sure mined vicinities. Lieutenant K. Shangin broke silence: - yesterday I...secondary branches. From the exploded rails were cut 3-4-meter healthy pieces, so-called logs were cut down. In field forges weee forged skids, the bolts

  15. 大跨人行悬索桥非线性静风稳定性分析%Nonlinear aerostatic stability analysis of a long-span suspension pedestrian bridge

    Institute of Scientific and Technical Information of China (English)

    薛晓锋; 管青海; 胡兆同; 李加武; 刘健新

    2014-01-01

    The nonlinear aerostatic stability of a 420m-main-span suspension pedestrian bridge was analysed numerically.Based on aerostatic coefficients of the main girder measured in wind tunnel tests,nonlinear influences caused by the structure and aerostatic load were analysed by using incremental double iteration method.The results conclude as follows:the structure deformation varying with wind speed shows obvious nonlinearity,and the aerostatic instability mode is of the characteristic of space deformation of bending-twisting coupling mode;comparing with the highway bridge,the torsional stiffness of the bridge due to main cables accounts for a greater proportion of the stiffness of the long-span suspension pedestrian bridge.The critical wind velocity and the reason of aerostatic instability can be got by tracing the stress in the main cable with the variation of wind speed;nonzero initial wind attack angle can reduce the critical wind speed;central buckles and anti-wind cables can raise the critical wind speed.The aerostatic instability mode after the installation of central buckles is the bending-twisting coupling mode of main girder,and the aerostatic instability mode after adding the measure of anti-wind cables is the local structural buckling due to the wind cables and hangers stress relaxation.The results are beneficial to the further research of long span narrow bridge aerostatic stability.%基于风洞试验所测加劲梁静力三分力系数,在综合考虑静风荷载非线性、结构几何非线性基础上,采用双重迭代计算分析方法对主跨420 m大跨窄人行悬索桥进行静风稳定性全过程分析。结果表明,结构变形随风速变化呈明显非线性,静风失稳形态弯曲扭转空间耦合变形特征显著;较公路桥大跨人行悬索桥主缆提供的扭转刚度比重更大,跟踪两主缆跨中应力随风速变化情况可定义静风失稳临界风速及与分析静风失稳原因;非零初始风攻角会降

  16. Risk Analysis and Countermeasures on Stage of Large Span Self - anchored Suspension Bridge Construction%大跨度自锚式悬索桥建设阶段风险分析及对策

    Institute of Scientific and Technical Information of China (English)

    李涛; 张傅洋

    2011-01-01

    Research purposes: All risks existing design and construction were recognized on design scheme of main bridge of Yangmeizhou bridge and structure system innovation using engineering risk assessment method and main risk factors were put forward. According to risk occurrence probability and risk loss, grade judgment of bridge risks was given. At last, preventive measures to reduce and control risk were proposed.Research conclusions; Four items of main risk factors were showed in this design by risk identification, namely? Structure system innovation risk of Long - span Self - anchored Suspension Bridges, adverse weather condition risk on construction safety,? Box beam? Multiple points incremental launching construction risk on deformation and stability, boats accidental collision risk on temporary piers during construction. According to risk occurrence probability and risk loss,the whole risk level belongs to the second grade, which could be accepted, and preventive measures should been put into implement to promote the safety of bridge construction.%研究目的:针对杨梅洲大桥主桥设计方案和结构体系创新,采用工程风险评估方法,对设计和施工中存在的各种风险进行识别,提出主要风险因素、风险发生概率和风险损失,给出本桥风险等级判别,提出降低和控制风险的防范措施.研究结论:(1)通过风险识别,提出了4项主要风险因素,即:大跨度自锚式悬索桥结构体系创新风险、恶劣气候条件对施工安全的影响风险、箱梁多点顶推施工对结构变形稳定的安全影响风险、施工期间通航船只对江中临时支墩的偶然碰撞风险;(2)根据风险发生概率和风险损失,确定了本桥的风险等级为Ⅱ级中度风险;(3)通过制定应对策略、采取抗风险措施等方法,可以达到将本桥建设风险降到最低程度、保证安全实施的目标.

  17. 青藏高原大跨度铁路连续刚构桥温度效应研究%Study on Temperature Effect of Long-span Continuous Rigid Frame Railway Bridges in Tibetan Plateau

    Institute of Scientific and Technical Information of China (English)

    李兆祥

    2014-01-01

    分析大跨度连续桥梁温度应力的影响,以拉日铁路雅鲁藏布江三号特大桥为例进行研究。采用 Midas Civil计算软件,对箱型截面的大跨度桥梁成桥后,在温度梯度作用下,对梁体的最大应力进行分析计算。采用 Midas FEA计算软件,分析箱型截面冬季施工养护期间,在箱体内部温度和高于外部温度的实测值下,分析单个现浇块体的应力值,为养护温度的设定提供参考依据。计算结果表明:温度对桥梁的应力影响较大,在西藏地区的温度变化快,温度较低的条件下,桥梁的抗裂能力能够满足当地气候条件。冬季施工期间,箱体内外养护温度差较大时会产生拉应力,必须合理的控制内外温度差和拉应力值,保证混凝土养护期间不开裂。%Analysis of the influence of temperature stress in long-span continuous bridge,in order to investigate this issue,take the 3rd Super Bridge of Brahmaputra as an example.Using the Mi-das Civil software to analyse the maximum stress of the the long-span bridge with box section af-ter completing bridge under the effect of the temperature gradient.Using the Midas FEA software to analyse the stress of the individual cast-in-place block,in the condition that the internal meas-ured temperature is higher than the external measured temperature during construction and main-tenance stage in winter,which can provide a reference for the settings of curing temperature.The calculation result shows that temperature has a great influence on the stress of bridge.In the con-dition of rapid temperature change and low temperature in Tibet,the crack resistance of the bridge can meet the local climatic conditions.During construction in winter,there would be tensile stress generated when curing temperature difference is large enough,so it is necessary to control the temperature difference between internal and external reasonable and tensile stress.ensured that the

  18. Numerical simulation and internal force analysis of large span wood arch lounge bridge%大跨木拱廊桥的数值模拟与内力分析

    Institute of Scientific and Technical Information of China (English)

    吕伟荣; 陈智; 王智丰; 梁炜; 周世军; 徐伟芬; 沈明燕

    2014-01-01

    木拱廊桥在中国乃至世界桥梁史上是一种独有的创造,它有着独特的构造特点与结构受力性能。运用Sap2000分析软件,对享有世界第一跨度的浙江丽水九龙国家湿地九龙木拱廊桥进行精细建模,研究廊桥在不同荷载工况下的结构内力和挠度,并对分析结果进行对比。分析结果表明,“三节苗”与“五节苗”在2类工况下均能实现各杆轴力均匀变化,而弯矩、剪力相对较小,实现了拱结构受力机制。%Timber arch lounge bridge is a unique creation in the history of China and even the world, it has a unique structure characteristics and structural performance. By using the ifnite element analysis software Sap2000, a reifned modeling has been carried out, for Jiulong Wood Arch Lounge Bridge in Zhejiang Lishui Jiulong National Wetland, which enjoys a worldwide reputation as a ifrst long-span bridge. The structural internal force and deflection under different load conditions were measured and studied. The results show that“Three bar”and“ifve bar”under two kinds of working conditions can both realize the uniform axial force changes, while the bending moment, shear force were relatively small, thus realizing the mechanism of arch structure.

  19. Dynamic Stability of Long-Span CFST Arch Bridge under Action of Near-Fault Ground Motions%近断层地震作用下大跨CFST拱桥的动力稳定性

    Institute of Scientific and Technical Information of China (English)

    邢帆; 祝兵; 赵灿晖

    2012-01-01

    In order to research the dynamic stability performances of long-span CFST ( concrete-filled steel tubular) arch bridges under the action of near-fault ground motions, an arch bridge with a 132 m main span was taken as the engineering background, and seismic records of the Chi-Chi earthquake in Taiwan, China were set as transverse inputs. The incremental dynamic analysis (IDA) was adopted to determine the critical load of dynamic instability. To increase the efficiency of IDA, the parallel high-performance numerical computing was employed. In addition, the problem of strengthening IDA curve cluster convergence was discussed. The research result shows that near-fault pulse-like ground motions are likely to bring about a great damage and result in nonlinear dynamical limit-load instability, and the corresponding critical load is decreased evidently. Weighted average peak ground acceleration, an new intensity measure, can make the discreteness of IDA curve cluster be improved significandy to avail to reveal the dynamic instability characteristics of CFST arch bridges caused by near-fault ground motions.%为研究大跨度CFST(钢管混凝土)拱桥在近断层地震作用下的动力稳定性能,以主跨132 m的下承式钢管混凝土拱桥为工程背景,以台湾集集地震记录作为横向输入,采用动态增量分析(IDA)方法,对动力失稳临界荷载的确定进行了探讨.为提高IDA的分析效率,采用了高性能数值计算并行处理方法.此外,还讨论了加强IDA曲线簇收敛的问题.结果表明:脉冲型近震可导致非线性极值动力失稳,失稳临界荷载明显降低;采用加权平均加速度峰值作为地震强度指标,能显著改善IDA曲线簇的离散性,有利于揭示近断层地震对钢管混凝土拱桥造成动力失稳的特点.

  20. Synthetical condition assessment of long span suspension bridge based on closeness degree and FAHP%基于贴近度与模糊层次分析的大跨悬索桥综合状态评估

    Institute of Scientific and Technical Information of China (English)

    郭彤; 李爱群; 赵大亮; 王浩

    2007-01-01

    Based on the theory of pattern recognition, the concept of closeness degree between fuzzy sets is brought into the condition assessment of long span bridges. Using the fuzzy analytic hierarchy process (FAHP),a mathematical model of a multi-objective assessment of a long span suspension bridge is set up. An example is given to show the procedure in the synthetical condition assessment of the Runyang Suspension Bridge, which includes the hierarchical division, the definition of factor weights and fuzzy membership functions, and the calculation of closeness degrees, etc. The assessment combines both the data from the health monitoring system and the manual tests. The classification of evaluation items as well as the calculation of deterministic and nondeterministic items is presented. Compared with the traditional method of point rating, this method can better describe the discreteness of monitoring data and the fuzziness in the condition assessment.%基于模式识别理论,将模糊集贴近度的概念引入大跨桥梁状态评估中,利用模糊层次分析,建立起大跨悬索桥多目标评估的数学模型.以润扬大桥悬索桥的综合状态评估为例,介绍了评估的基本程序,包括评估指标的层次划分、指标权重的确定、模糊集隶属函数的定义以及贴近度的计算等.评估综合了健康监测系统的采集数据和人工监测结果2方面的信息,同时还给出了评估指标的分类方法和确定性指标、不确定性指标的计算方法.与传统的专家打分法相比,该方法更好地体现了监测信息的离散性、不确定性和评估过程的模糊性.

  1. Taizhou Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    Taizhou Bridge lies between Taizhou, Zhenjiang and Changzhou City in Jiangsu Province. The total length of Taizhou Bridge is 62.088 kin. The whole line is designed by freeway codes with six lanes in two directions. The wholeinvestment is 9.37 billion RMB and the planned construction duration is 5.5 years. The main bridge crossing the Yangtze River is a continuous three-pylon two-span suspension bridge with the main span of 1 080 m. The bridge system is realized for the first time and ranks first in the world until now.

  2. 大跨度桥梁各态历经脉动风场的数值模拟分析%Numerical study on ergodic fluctuating wind field of long-span bridge

    Institute of Scientific and Technical Information of China (English)

    郑恒斌; 颜全胜; 王卫锋; 吴杰

    2012-01-01

    On the basis of the spectral representation method with proper orthogonal decomposition ( POD) , considering the features of fluctuating wind field of long-span bridges, a reduction simulated formula of fluctuating wind field, which considered the cross-spectral density matrix as the POD object, was deduced. The equation of end error calculation based on the energy criterion was adopted to estimate the rational truncation item number of eigenvalues. And by introducing the double-indexing of the frequencies, the simulation of ergodic time domain series was achieved. Also, the Fast Fourier Transform was adopted to improve calculation efficiency, and the improved formula based on the Fast Fourier Transform was deduced in order to program expediently. In addition, the algorithm was applied to simulate the beam stochastic wind field of a long-span railway continuous rigid frame bridge. The auto-power spectral density and cross-power spectral density of the simulated time domain samples show good agreement with target spectrum, which can verify the effectiveness and correctness of the algorithm. Finally, the algorithm resultant velocity of wind field was analyzed. Results indicate that the key point of influencing the algorithm calculation efficiency is the POD velocity of matrix.%基于本征正交分解(proper orthogonal decomposition,POD)的谱表示法,结合大跨度桥梁脉动风场的特点,推导出一种以互谱密度矩阵为POD对象的脉动风场模拟简化公式.采用以能量评判为准则的误差精确公式,对特征值合理截断阶数进行估计.引入双索引频率,实现了模拟样本的各态历经性.采用快速傅里叶变换(fast Fourier transform,FFT)对算法加速,给出了简化模拟公式在FFT算法下的具体表达式,便于程序编制.利用该法模拟了一座大跨度铁路连续刚构桥的主梁脉动风场,所得样本自功率谱和互功率谱均与目标谱吻合良好,验证了该方法的有效性和正确性.对

  3. Evaluation of Seismic Performance of Long Span Continuous Girder Bridges Based on Seismic Isolation Design%基于减隔震设计的大跨度连续梁桥抗震性能评价

    Institute of Scientific and Technical Information of China (English)

    李贞新; 刘高

    2011-01-01

    Nonlinear time history analysis method is adopted to analyze dynamic characteristics and seismic performance based on long span continuous girder bridges with spans of 89 m, 170 m and 89 m in high intensity region. The good hysteretic, energy-dissipation characteristics and self-restoring ability of double curvature seismic isolation bearings are simulated as well as the friction energy-dissipation characteristics of sliding bearing and damping energy-dissipation characteristics of dampers. Analytical results indicate that seismic performance can basically meet the expected design goal; seismic isolation device of double curvature spherical supports and dampers can adjust dynamic characteristics, reduce seismic response, dissipate earthquake energy and guarantee the safety of the structure.%基于高烈度区的某大跨度连续梁桥(89 m+170 m+89 m),采用非线性时程分析法进行结构动力特性及抗震性能分析.全桥均采用三维梁单元建立空间模型,对于双曲面球形减隔震支座的滞回耗能特性和自恢复功能,活动支座的摩擦耗能以及固定销剪断后的效应进行了模拟,同时模拟了阻尼器的阻尼耗能作用.研究结果表明:采用双曲面球形减隔震支座及桥台处纵向阻尼器后,结构的反应得到了很好的控制,确保了高烈度区结构的抗震安全性.

  4. Foundations and anchors for a 250 m span arch bridge in la Palma Island (Canaries); Cimentaciones y anclajes para la construccion del Arco de los tilos, de 250 m. de luz, en la isla de la Palma (Canarias)

    Energy Technology Data Exchange (ETDEWEB)

    Simic Sureda, D.

    2008-07-01

    There are no simple procedures to estimate the bearing capacity of direct foundations on rock due to its anisotropy, as the criteria have to take into account different features concerning the rock discontinuities (spacing, orientation, opening, persistence,...) as well as other aspects concerning the rock matrix, particularly its strength when it is low. In this sense, the volcanic formations of the Canary Island pose important difficulties to the designer of foundations given their highly anisotropic fabric, which is the result of a complex origin where the basalt sheets alternate with fragmentary material of pyroclastic nature. This volcanic building is frequently intersected by old vents, in the guise of pipes plugged with broken fragments of low compacity. In a valley of highly dissected steep slopes of such geology an arch bridge has been designed and built with a span between supports of 250 m. This paper describes the analysis that was carried out to take into account the particularities of rock anisotropy and the foundations geometry in very steep slopes. The construction problems are also addressed in the paper, describing the grouting treatment that was needed in one of the supports due to the presence of an old vent. (Author) 7 refs.

  5. Force transmission mechanism and fatigue behavior of a pin-connection anchor of hanger for a long-span suspension bridge; Chodai tsurihashi no hanga ropu pin teichakubu hokyo kozo no chikara no dentatsu kiko to hiro kyodo

    Energy Technology Data Exchange (ETDEWEB)

    Ohashi, H. [Honshu-Shikoku Bridge Authority, Tokyo (Japan); Fujii, Y. [Honshu-Shikoku Bridge Authority, Kagawa (Japan); Ono, S. [Construction Method and Machinery Research Inst. of J.C.M.A, Shizuoka (Japan); Miki, C. [Tokyo Inst. of Tech. (Japan). Faculty of Engineering

    1996-04-21

    In a long-span suspension bridge having a stiffening truss, a large angular bend of a hanger occurs due to the relative displacement of a main cable and a stiffening girder occurring during a storm. This paper describes the production of a life size specimen with importance attached to a fixed portion of a one-way pin which is in a severe stress condition, and the measurement of the stress condition of a fixing plate and a reinforcing plate near a pin hole of a pin fixing structure, the contact condition of the pin with the pin hole and the bending stress of the pin. The paper further describes a fatigue test conducted in a stormy weather condition. The results of an investigation into two types of contact condition of the pin and pin hole clearly show that the pin is in a one-side contact state during a storm, not in a uniform contact state even in a normal condition due to the unevenness of the inner surface of the pin hole. Therefore, the load of the hanger is not evenly transmitted to the connection plate and reinforcing plate. Consequently, it is necessary to discuss in the future the size and quality of a weld at which the connection plate and reinforcing plate are joined together so as to attain reliable transmission of the load. 4 refs., 14 figs., 2 tabs.

  6. Analysis of Static, Dynamic and Seismic Performance of Long Span Irregular-Shape Pedestrian Cable-Stayed Bridge%大跨人行异型斜拉桥静、动力及抗震性能分析

    Institute of Scientific and Technical Information of China (English)

    刘世明; 赵顺波; 李晓克

    2012-01-01

    为研究异型斜拉桥结构安全,静、动力以及抗震性能是否满足规范要求,以某大跨人行异型斜拉桥为工程背景,采用MIDAS Civil有限元分析软件,结合桥梁施工方法,对结构进行了考虑混凝土的收缩、徐变、温度等作用的静力特性及动力特性、空气动力稳定以及抗震性能分析.结果表明:塔、梁各截面承载力均满足规范要求;结构基本周期比较短,能减少结构的地震位移,但对桥塔底部受力不利,主梁竖向弯曲的第1阶频率不符合规范(大于3 Hz)要求,需要进行特殊设计,自振特性表现出明显的相互耦合的特点,随着频率的提高,结构扭转所占比重增大,对该桥的横向稳定不利;空气动力稳定良好;在E1地震作用下,结构的应力响应较小,结构刚度较大.%To study the structural safety of long span irregular-shape pedestrian cable-stayed bridge and to check if the static, dynamic and seismic performance of the bridge can meet the relevant requirements in the codes, an actual pedestrian cable-stayed bridge of the same type was cited as an example. By means of the finite element analysis software MIDAS Civil and with reference to the construction methods to be used for the bridge, the static and dynamic characteristics, the aerodynamic stability and seismic performance of the structure were analyzed, taking into account of the action of concrete shrinkage, creep and temperatures. The results of the analysis indicate that the bearing capacity of various sections of the pylon and girder of the structure can meet the requirements in the codes, the basic period of the structure is short and can reduce the displacement of the structure caused by earthquake, but it is unfavorable to the force conditions of the pylon footing. The 1st order frequency of vertical bending of the main girder does not meet the requirements (greater than 3 Hz) in the codes and should be specially dealt with in the design. The

  7. Plastic Bridge

    Institute of Scientific and Technical Information of China (English)

    履之

    1994-01-01

    Already ubiquitous in homes and cars, plastic is now appearing inbridges. An academic-industrial consortium based at the University ofCalifornia in San Diego is launching a three-year research program aimed atdeveloping the world’s first plastic highway bridge, a 450-foot span madeentirely from glass-,carbon,and polymer-fiber-reinforced composite mate-rials, the stuff of military aircraft. It will cross Interstate 5 to connect thetwo sides of the school’s campus.

  8. 港珠澳大桥非通航孔桥钻孔平台施工方案比选%Comparison and Selection of Construction Schemes for Boring Platform of Non-Navigable Span Bridge of Hong Kong-Zhuhai-Macau Bridge

    Institute of Scientific and Technical Information of China (English)

    刘运洪

    2015-01-01

    The non‐navigable span bridge of Contract CB05 of the Hong Kong‐Zhuhai‐Macao Bridge is a 85‐m span steel and concrete continuous composite girder bridge .The foundations for the piers of the bridge are the ones of steel pipe composite piles .At each pier ,6 composite piles are provided and there are totally 372 piles for the whole bridge .In the light of the structural fea‐tures and construction difficulties of the bridge ,the construction schemes of a common boring plat‐form of the"steel pipe piles+ sectional steels" structure (Scheme 1) and an integral boring plat‐form of the"integral steel truss type"structure (Scheme 2) were proposed for construction of the foundations .T hrough comparison of those aspects of the civilization construction ,safety ,environ‐ment protection ,construction efficiency and construction cost ,it was determined that the Scheme 2 should be selected .For the Scheme 2 ,the components of the boring platform were all fabricated in workshop following the standardization requirements and were welded into the integral steel truss structure .The steel truss structure was then transported by ship to the pier site where the structure would be installed or integrally removed for repeated usage at other pier sites by floating crane and at this stage , the construction of the boring platform was completed . The selected Scheme 2 can effectively shorten the time interval of shifting the platform from pier site to pier site and has advantages of high efficiency , safety , environment protection , energy saving and fast speed .%港珠澳大桥CB05标非通航孔桥为跨径85 m的钢-混组合连续梁桥,采用钢管复合桩基础,每墩均由6根钢管复合桩组成,全桥共372根。针对该桥结构特点和施工难点,桩基础施工提出了“钢管桩+型钢”结构的普通钻孔平台(方案1)和“整体桁架式”结构的整体钻孔平台(方案2)施工方案,通过文明施工、安全环保、

  9. 33 CFR 118.85 - Lights on vertical lift bridges.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of the...

  10. Seismic performance evaluation of retrofit measures for multi-span simple-supported bridges%多跨简支梁桥加固措施的抗震性能评估

    Institute of Scientific and Technical Information of China (English)

    朱文正

    2015-01-01

    This paper conducts a nonlinear time-history analysis of a typical 5-span simply supported bridge by using three-dimensional models to evaluate the effectiveness of various retrofit measures. Restrainer cables, concrete jackets, elastomeric bearings, and lead rubber bearings are assessed for their influence on the variability of critical components in the bridge. The results indicate that each retrofit measure may be effective for components of the bridge in different degrees. The restrainer cables and lead-rubber bearings ( LRBs) are effective in controlling the relative deformation between girders and piers;LRBs and elastomeric bearings improve the response of the vulnerable columns, elastomeric bearings lead to increased abutment demands, and a larger value can be chosen for the initial gap of the restrainer cable based on the permitted deformations of the bearings. Additionally, it is recommended to replace these fixed bearings with elastomeric bearings or LRBs, and to enhance ductility capacity of the columns with concrete jackets when necessary. The results can be used for vulnerability assessments that consider the impact of retrofit on system vulnerability reflecting the contribution of multiple components.%对一座典型的五跨简支铁路箱梁桥进行了多种工况的非线性地震反应分析,评价限位拉索、混凝土墩套、橡胶支座和铅芯橡胶支座等措施对桥梁主要构件抗震性能的影响。结果表明,各措施对桥梁构件的抗震性能有不同程度的改善,限位拉索和铅芯橡胶支座可以有效消减使用活动支座或普通橡胶支座时墩梁的相对位移;铅芯橡胶支座和普通橡胶支座均显著减少了桥墩的延性需求,但普通橡胶支座加大了墩梁间的相对位移和梁体对桥台的碰撞;限位拉索的初始间隙可考虑支座的允许变形,适当取较大值。建议采用铅芯橡胶支座或普通橡胶支座更换固定支座,必要时采用增加

  11. Bridge Crossing Simulator

    Science.gov (United States)

    2014-10-07

    Requirement BCS Computer-controlled hydraulic actuation system to impart simulated crossing loads on an entire bridge structure undergoing fatigue test ...structure. Bridge test site with prepared embankments corresponding to the span and bank condition requirements of the bridge under test Conduct real...Center (AEC). (5) Sample size and number of crossings required. The number of required simulated crossings to conduct fatigue testing per the

  12. Dynamic Bridge Response for a Bridge-friendly Truck

    Directory of Open Access Journals (Sweden)

    V. Šmilauer

    2004-01-01

    Full Text Available A truck with controlled semi-active suspensions traversing a bridge is examined for benefits to the bridge structure. The original concept of a road-friendly truck was extended to a bridge-friendly vehicle, using the same optimization tools. A half-car model with two independently driven axles is coupled with simply supported bridges (beam, slab model with the span range from 5 m to 50 m. Surface profile of the bridge deck is either stochastic or in the shape of a bump or a pot in the mid-span. Numerical integration in the MATLAB/SIMULINK environment solves coupled dynamic equations of motion with optimized truck suspensions. The rear axle generates the prevailing load and to a great extent determines the bridge response. A significant decrease in contact road-tire forces is observed and the mid-span bridge deflections are on average smaller, when compared to commercial passive suspensions. 

  13. 大跨桥梁振动的杠杆调谐质量阻尼器控制策略评价%Performance Assessment of Lever-type Tuned Mass Damper for Long-span Bridges

    Institute of Scientific and Technical Information of China (English)

    李春祥

    2005-01-01

    根据建立的LT-TMD-结构系统的动力放大系数解析式,讨论了LT-TMD的动力特性(包括冲程).数值结果表明,LT-TMD和传统的TMD具有相同的控制有效性和冲程;然而,LT-TMD比传统的TMD具有更大的最优调谐频率比和更小的最优阻尼比.LT-TMD的关键优点是可通过移动支撑的位置来限制LT-TMD弹簧的静力和动力伸长而保持其控制有效性和冲程不变.鉴于此 ,LT-TMD可能是控制大跨桥梁振动的一种较好的策略.%Employing the derived analytical expressions for the dynamic magnification fact ors of the lever-type tuned mass damper (LT-TMD) structure system, the perform ance assessment (including the stroke displacement) of the LT-TMD is carried ou t. The numerical results indicate that the LT-TMD may achieve the same effectiv eness and stroke displacement as the tuned mass damper (TMD). However, the LT-T MD needs higher optimum tuning frequency ratio and lesser optimum damping r atio with reference to the TMD. A key advantage of the LT-TMD, compared to the TMD, is that the static stretching of the spring of the LT-TMD may be adjuste d in accordance with the practical requirements through changing the locations o f the support while maintaining the same effectiveness and stroke displacement a s the TMD. In view of this, the LT-TMD may be a better choice for suppressing t he vibrations of long-span bridges with the consequence but not permitting a la rge static stretching of the spring in practical implementation.

  14. Identification Method of Flutter Derivative of Long-span Bridge in Tandem with Uncertain Aerodynamic Interference Effect%不确定气动干扰效应影响下并列大跨度桥梁颤振导数识别方法

    Institute of Scientific and Technical Information of China (English)

    祝志文; 李友祥; 陈政清

    2011-01-01

    将处于自然风中一前一后并列布置的大跨度桥梁相互之间可能存在的不确定相互气动干扰处理成随机气动干扰,并归入到紊流风随机激励中,采用基于模态参数识别的随机子空间识别方法,开发了桥梁断面颤振导数识别的专用程序,并以具有理论解的Theodorsen平板为例,通过系统响应数值仿真和颤振导数识别,验证了该方法的可靠性。针对实际大跨度桥梁,设计了并列节段模型试验悬挂系统,开展了紊流风和随机气动干扰效应下的并列大跨度桥梁节段模型风洞试验,将迎风、背风侧桥梁断面的颤振导数结果与均匀流、紊流风中单个桥梁断面颤振导数值进行了对比。结果表明:背风侧桥梁对迎风侧桥梁的颤振导数影响很小,而迎风侧桥梁对背风侧桥梁的颤振导数有较大影响;该研究方法为存在这种随机气动干扰的并列大跨度桥梁颤振导数识别提供了一个较为合理的途径。%Uncertain interactive aerodynamic interference of two long-span bridges in tandem which located very closely in turbulent wind was treated as stochastic aerodynamic interference, and was included into stochastic turbulent wind excitation. Based on the stochastic subspace identification (SSI) method of modal parameter identification, specified program of flulter derivative of bridge section was developed. Taking Theodorsen thin plate with theoretical solution as example, the method was validated through system response simulation and identification of flutter derivative. Aimed at practical long-span bridge, suspension system of sectional model test in tandem was designed. Wind tunnel test of sectional model of long-span bridge in tandem under turbulent wind and stochastic aerodynamic interference effect was carried out. Flutter derivative results of windward and leeward bridge section got by the test were compared with flutter derivative value of single

  15. 广深港客运专线工程大跨度桥梁施工关键措施的研究%Research on the key measures of large span bridge construction Guangzhou-Shenzhen-Hong Kong passenger dedicated line engineering

    Institute of Scientific and Technical Information of China (English)

    李锦平; 钱治国

    2013-01-01

    In this paper,the related key technologies of Guangzhou-Shenzhen-Hong Kong Passenger Dedicated Line Engineering Shawan Waterway Bridge construction process as an example,combining the Shawan bridge natural conditions, geologic al,hydrological,climatic conditions;some like engineering in the advanced technology was adopted to ensure the safety and quality of the control engineering,especially to make some study of the process of the construction of large span bridge technology, research on a series of large span bridge construction technology of passenger dedicated line,not only can be used for the construction of Shawan Waterway Bridge,and construction of other similar projects are very important,valuable reference.%  本文以广深港客运专线工程沙湾水道特大桥施工过程的相关的关键技术为例,结合该沙湾水道特大桥施工的自然条件、地质、水文、气候条件;为确保该控制性工程的安全与质量采取了一些在类似工程的先进技术,尤其对大跨度桥梁施工过程中的技术做出了一些研究,研究了一系列关于客运专线上大跨度桥梁施工技术,不仅可以用于沙湾水道特大桥的施工,而且对其它类似工程的建设还有非常重要的、宝贵的借鉴意义。

  16. 33 CFR 118.80 - Lights on bascule bridges.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on bascule bridges. 118.80 Section 118.80 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.80 Lights on bascule bridges. (a) Lift span lights. Each lift span...

  17. 49 CFR 237.33 - Content of bridge management programs.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 4 2010-10-01 2010-10-01 false Content of bridge management programs. 237.33... Content of bridge management programs. Each bridge management program adopted in compliance with this part... spans, span lengths, and all other information necessary to provide for the management of bridge...

  18. History of cable-stayed bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    The principle of supporting a bridge deck by inclined tension members leading to towers on either side of the span has been known for centuries. However, the real development of cable-stayed bridges did not begin before the 1950s. Since then the free span has been increased from 183 m...... in the Strömsund Bridge (from 1955) to 890 m in the Tatara Bridge (from 1999)....

  19. Assessment of Structural Damage of a Long Span Continuous Rigid-Frame Bridge with Bursting Cracks in Its Bottom Slab%某大跨径连续刚构桥底板崩裂后的结构损伤评估

    Institute of Scientific and Technical Information of China (English)

    崔学常; 杨植春

    2015-01-01

    为评估某大跨径预应力混凝土连续刚构桥[跨度为(96+132+96) m ]底板崩裂后(崩裂长度最长为26.0 m ,崩裂厚度最大达30 cm )的结构损伤程度,确定合理的处理方案,采用M I‐DAS Civil 2010建立全桥有限元模型,分析了桥梁各种损伤量化参数,建立了损伤模型,对损伤前、后主梁的顶、底板应力进行计算分析。结果表明,在主力+附加力作用下,损伤后主梁底板出现拉应力(0.25 M Pa ),桥梁损伤较为严重,不能满足《铁路桥涵钢筋混凝土和预应力混凝土结构设计规范》的设计要求。建议后续不仅要对崩裂底板进行修复,而且要对桥梁进行全面的加固改造(如设置体外预应力,增加顶板厚度等),以提高其整体刚度和承载力,保证桥梁结构后续运营的安全。%To assess the structural damage degree of a long span prestressed concrete continu‐ous rigid‐frame bridge with span arrangement (96 m+132 m+96 m) with bursting cracks in its bottom slab (the maximum bursting crack length and depth respectively being 26 .0 m and 30 cm) and to determine the rational scheme for handling the cracks ,the MIDAS Civil 2010 was used to set up the finite element model for the w hole bridge of the bridge and the various quantitative pa‐rameters of the damage of the bridge were analyzed .The damage models were set up as well and the stress of the top and bottom slabs of the main girder of the bridge before and after the bridge was damaged was calculated and analyzed .The results of the calculation and analysis indicate that under the action of the main force+additional forces ,the tensile stress (0 .25 M Pa) occurs in the bottom slab of the damaged bridge ,the damage of the bridge is rather severe and can not meet the design requirements in the Code for Design on Reinforced and Prestressed Concrete Structure of Railw ay Bridge and Culvert .It is hence proposed that the

  20. Spanning Tree Problem

    Directory of Open Access Journals (Sweden)

    Yen Hung Chen

    2012-01-01

    minimum cost spanning tree T in G such that the total weight in T is at most a given bound B. In this paper, we present two polynomial time approximation schemes (PTASs for the constrained minimum spanning tree problem.

  1. Study on control of cantilever construction of long-span continuous rigid frame bridges%大跨连续刚构桥悬臂施工控制研究

    Institute of Scientific and Technical Information of China (English)

    彭立强; 刘超; 王冲

    2015-01-01

    随着连续刚构桥施工技术的不断进步,悬臂浇筑成为在实际工程中使用最为广泛的一种连续刚构桥施工方法。在悬臂施工过程中,由于桥梁结构存在由静定结构转变为超静定结构的过程,因此在施工过程中要注意对桥梁线型、内力、预拱度以及挠度等因素进行施工过程监控,以满足桥梁结构的要求。%In recent years, with the continuous progress of the construction technology of continuous rigid frame bridge, cantilever pouring are widely used in practical engineering as a continuous rigid frame bridge construction method. There is a process for bridge structure to change from static structure to hyperstatic struc-ture in the process of the cantilever construction. Therefore, attention should be paid to the bridge linear, in-ternal forces, camber and deflection factors during the construction in order to meet the requirements of the bridge structure.

  2. Key Technology of the Fabrication and Erection of Steel-concrete Composite Girder on Integral Span of Hong Kong-Zhuhai-Macao Bridge%港珠澳大桥钢-混组合梁制造及安装关键技术

    Institute of Scientific and Technical Information of China (English)

    王艳峰; 潘军

    2015-01-01

    港珠澳大桥浅水区非通航孔桥上部结构采用钢-混组合连续梁。文中主要从桥面板预制、钢主梁整孔制造、钢主梁桥面板组合、组合梁整孔运架,以及组合梁体系转换技术方面阐述了组合梁整孔制造整孔架设技术,体现了大型构件海上施工的“大型化、标准化、工厂化、装配化”理念。%The non-navigable bridge in the shallow water area of the Hong Kong-Zhuhai-Macao Bridge is made of steel-concrete composite structure in the form of continuous box girder structure.This arti-cle expounded the technology of integral fabrication and erection on box girder from fabrication of the precast concrete bridge deck,fabrication of integral span on box girder,combined with steel box gird-er and bridge deck,transport and erection on composite girder,stress system transformation on com-posite girder.It shows the advanced construction concept which is″large-scale,industrialized,stand-ardized and assembled″ in the marine construction.

  3. Floating-hauling Construction Technique for Large-span,Heavy-weight Leaning-type Tied Arch Bridge%大跨度、大重量斜靠式系杆拱桥浮拖法施工技术研究

    Institute of Scientific and Technical Information of China (English)

    刘强华

    2016-01-01

    基于100 m 跨径云梨桥斜靠式钢箱系杆拱桥工程,介绍浮拖法施工技术在大跨度、大重量偏心斜靠式系杆拱桥施工中的应用,分析系杆拱桥整体浮拖中的关键工序和控制措施,针对云梨桥浮拖过程中的复杂性,应用空间有限元分析程序,进行了关键施工阶段的应力、变形分析,解决了浮拖过程中的稳定性问题。%Based on the project of leaning-type steel-box-tied arch Yunli Bridge with 100 m span,this paper introduces the construction technology of floating-hauling method in large-span and large-weight leaning-type eccentric tied arch bridge construction,then it analyzes the application of the key working procedure in tied arch bridge during overall floating-hauling construction and its control measures.For the complexity in floating-hauling construction of Yunli Bridge,space finite ele-ment analysis program is applied to analyze the stress and deformation in the key construction stage,and it solves the stabil-ity problem in the process of floating-hauling construction.

  4. The Akashi Kaikyo Bridge and the Storebælt Bridge

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    With the completion of the Akashi Kaikyo Bridge and the Storebælt East Bridge the development of the suspension bridge technology in the 20th century has manifested itself in two impressive structures. With the present echnology may bridges of similar (and also more modest) dimensions...... will undoubtedly be built far into the next century. For bridges going beyond the spans of existing bridges it is, however, likely that new concepts will be developed....

  5. Field performance of timber bridges. 5, Little Salmon Creek stress-laminated deck bridge

    Science.gov (United States)

    M. A. Ritter; J. A. Kainz; G. J. Porter

    The Little Salmon Creek bridge was constructed in November 1988 on the Allegheny National Forest in Pennsylvania. The bridge is a simple span, single-lane, stress-laminated deck superstructure that is approximately 26-ft long and 16-ft wide. The bridge is unique in that it is the first known stress-laminated timber bridge to be constructed of hardwood lumber. The...

  6. Field performance of timber bridges. 6, Hoffman Run stress-laminated deck bridge

    Science.gov (United States)

    M. A. Ritter; P. D. Hilbrich Lee; G. J. Porter

    The Hoffman Run bridge, located just outside Dahoga, Pennsylvania, was constructed in October 1990. The bridge is a simple-span, single-lane, stress-laminated deck superstructure that is approximately 26 ft long and 16 ft wide. It is the second stress-laminated timber bridge to be constructed of hardwood lumber in Pennsylvania. The performance of the bridge was...

  7. 33 CFR 118.65 - Lights on fixed bridges.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on fixed bridges. 118.65 Section 118.65 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.65 Lights on fixed bridges. (a) Each fixed bridge span over a...

  8. 33 CFR 118.70 - Lights on swing bridges.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Lights on swing bridges. 118.70 Section 118.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.70 Lights on swing bridges. (a) Swing span lights on through bridges....

  9. Finite element of multilayer surfacing systems on orthotropic steel bridges

    NARCIS (Netherlands)

    Li, J.; Liu, X.; Scarpas, A.; Tzimiris, G.

    2013-01-01

    Light weight orthotropic steel bridge decks have been widely utilized for bridges in seismic zones, movable bridges and long span bridges. In the last three decades, severe problems were reported in relation to asphaltic surfacing materials on orthotropic steel deck bridges. Earlier investigations h

  10. History of cable-stayed bridges

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    The principle of supporting a bridge deck by inclined tension members leading to towers on either side of the span has been known for centuries. However, the real development of cable-stayed bridges did not begin before the 1950s. Since then the free span has been increased from 183 m in the Strö...

  11. Puentes. Puente de Mackinac

    Directory of Open Access Journals (Sweden)

    Steinman, David B.

    1958-11-01

    Full Text Available En el número 82 de nuestra revista se publicó un trabajo que se refería únicamente a la infraestructura de esta importante obra. En esta segunda parte damos a conocer las características más sobresalientes de la propia superestructura, estabilidad, métodos constructivos empleados en el montaje y el procedimiento que se ha seguido para lograr colocar los cables, de 12.500 toneladas de peso total, sobre las dos torres del tramo central, de 1.158 m de luz, método que ha consistido en formar los cables, partiendo de las bobinas de alambre, en la propia obra.

  12. Building a Straw Bridge

    Science.gov (United States)

    Teaching Science, 2015

    2015-01-01

    This project is for a team of students (groups of two or three are ideal) to design and construct a model of a single-span bridge, using plastic drinking straws as the building material. All steps of the design, construction, testing and critiquing stages should be recorded by students in a journal. Students may like to include labelled diagrams,…

  13. General design of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Xigang; Yuan Hong; Pei Minshan; Dai Jie; Xu Lin

    2009-01-01

    The main span of Sutong Bridge is a double-pylon, double-plane cable-stayed bridge with steel box girder, which has the world's longest central span of 1 088 m within cable-stayed bridges. To overcome problems caused by severe meteorological conditions, perplexing hydrological conditions, deep buried bedrock and higher navigation level, many new technics and methods were created. Keys including structural system, steel box girder, stayed cable, tower, pier, tower foundation, collision avoidance system, wind-resistance, seismic-resistance, structural nonlinear response and structural static stability were presented individually in this paper.

  14. 基于支持向量机的高墩大跨桥梁体系可靠度计算%Computation of Structural System Reliability of High-Rise Pier and Long Span Bridge Based on Support Vector Machine

    Institute of Scientific and Technical Information of China (English)

    张士福; 康海贵; 郑元勋; 李玉刚

    2012-01-01

    为解决高墩大跨桥梁结构体系可靠度求解过程中失效模式复杂、极限状态方程无法显式表达等问题,提出一种基于支持向量机(SVM)分类技术的体系可靠度计算方法.该方法采用拉丁超立方抽样法产生样本库,通过重复筛选构造一个精确的SVM分类器函数(而不是构造功能函数本身的响应面函数),然后采用蒙特卡罗法进行数值模拟计算体系失效概率.以济邵高速公路逢石河特大桥为例验证了采用该方法计算高墩大跨桥梁体系可靠度的实用性,计算结果表明该桥体系可靠度满足设计要求.%To cope with the problems that the failure modes in the solving process of structural system reliability of high-rise pier and long span bridge are complicated and the limit state e-quations can not be displayed and expressed, a method for computation of the system reliability based on the support vector machine (SVM) classification technique is proposed. The proposed method can generalize the sample bank, using the Latin hypercube sampling method and can construct a precise SVM classifier function (rather than the response surface function of the structure function itself) by repeated screening and the numerical simulation and computation of the system failure probability are accordingly carried out, using the Monte Carlo method. By way of example of the Fengshi River Bridge on Jiyuan-Shaoyuan Expressway, the practicability of the method for computation of the system reliability of the high-rise pier and long span bridge is verified and the results of the computation prove that the system reliability of the bridge can meet the design requirements

  15. Railroad Bridges

    Data.gov (United States)

    Department of Homeland Security — Bridges-Rail in the United States According to The National Bridge Inspection Standards published in the Code of Federal Regulations (23 CFR 650.3), a bridge isA...

  16. Closure technique for the hybrid girder cable stayed bridge of Edong Bridge

    Institute of Scientific and Technical Information of China (English)

    Liu Minghu; Tan Hao; Xu GuoPing; Zhao Canhui

    2012-01-01

    Based on Edong Yangtze River Bridge, which is the second longest hybrid girder cable stayed bridge with 926 m long main span, the influencing factors and crucial techniques of the main span closure method for long span hybrid girder cable stayed bridge are studied. After theoretical analysis, numerical evaluation and practical test, the loading assistant closure method is employed in Edong Yangtze River Bridge. The loading assistant closure method, with better thermal adaptability and less influence on bridge line and the forced status, can meet the requirements of the unstressed state control method. Based on the mentioned advantages, the loading assistant closure method is applicable to long span hybrid girder cable stayed bridges. The conclusion can provide a reference for the further design of the similar brid~es.

  17. 考虑非线性影响的大跨度钢管混凝土拱桥的静风响应分析%Analysis of Static Wind Response of large-span CFST Arch Bridge Considering the Nonlinear Effect

    Institute of Scientific and Technical Information of China (English)

    杨万标; 范存新

    2015-01-01

    以巫峡长江大桥为研究背景,分别研究几何非线性以及几何和材料双重非线性对大桥拱肋在静风荷载作用下内力与位移响应的影响。结果表明:在静风荷载作用下,几何非线性和双重非线性对该桥拱顶的横向位移和扭转位移以及拱肋的面外弯矩影响比较显著,故在进行大跨度钢管混凝土拱桥静风响应分析时不可忽略非线性的影响。%Taking the Wu Gorge Bridge over Yangtse River as the research background, the effect of geometrical nonlinearity and geometric and material double nonlinear to the internal force and displacement response of the arch rib of the bridge under the action of static wind load were studied. The results showed that: under the static wind load, geometry nonlinear and double non-linear have an obvious influence on the lateral displacement, the torsion displacement and the out-of-plane bending moment of the arch. The influence of the nonlinearity can not be ignored in the process of long-span concrete-filled steel tube arch bridge static wind response analysis.

  18. Carbon-based tendons in the Dintelhaven Bridge, the Netherlands

    NARCIS (Netherlands)

    Vervuurt, A.H.J.M.; Kaptijn, N.; Grundlehner, W.B.

    2003-01-01

    In mid-2001 the final two bridges over the River Dintelhaven in the harbour area of Rotterdam were put into use. Both bridges are concrete box girder bridges and have been erected using the balanced cantilever method. In the first bridge, with a main span of about 185 m, four (external) tendons each

  19. Comfort Evaluation of Riding Vibration for Large-span Cable-stayed Bridge%大型桥梁行车振动舒适性的烦恼率模型研究

    Institute of Scientific and Technical Information of China (English)

    李雪红; 周叶波; 徐秀丽; 刘伟庆; 李枝军

    2011-01-01

    针对目前国内外对行车振动舒适性的度量及具体判定上还有一定的模糊性,迫切需要定量化的评价方法.本文结合振动舒适度标准和国际上公认的振动舒适度实验,分析了概念隶属度值和相应的振动加速度对数值之间的关系,给出了烦恼率计算公式,提出了烦恼率的近似拟合曲线,并把烦恼率作为行车振动舒适性的量化指标,提出评价行车振动舒适性较精确的量化方法;并将其用于实际运营的大跨桥梁的行车振动舒适性评价.%According to disadvantage of fuzziness for judgment of riding comfort of the bridge, quantitative evaluation method is needed. Combining riding comfort standard and internationally accepted riding comfort experiment, definition of membership and relationship between corresponding vibration acceleration and value are analyzed; annoyance rate calculation formula is researched; approximate fitting curve of annoyance rate is put forward. A more accurate quantitative method to evaluate riding comfort is proposed, with annoyance rate as quantitative index of riding comfort.

  20. Life Span Developmental Approach

    Directory of Open Access Journals (Sweden)

    Ali Eryilmaz

    2011-03-01

    Full Text Available The Life Span Developmental Approach examines development of individuals which occurs from birth to death. Life span developmental approach is a multi-disciplinary approach related with disciplines like psychology, psychiatry, sociology, anthropology and geriatrics that indicates the fact that development is not completed in adulthood, it continues during the life course. Development is a complex process that consists of dying and death. This approach carefully investigates the development of individuals with respect to developmental stages. This developmental approach suggests that scientific disciplines should not explain developmental facts only with age changes. Along with aging, cognitive, biological, and socioemotional development throughout life should also be considered to provide a reasonable and acceptable context, guideposts, and reasonable expectations for the person. There are three important subjects whom life span developmental approach deals with. These are nature vs nurture, continuity vs discontinuity, and change vs stability. Researchers using life span developmental approach gather and produce knowledge on these three most important domains of individual development with their unique scientific methodology.

  1. Dual boundary spanning

    DEFF Research Database (Denmark)

    Li-Ying, Jason

    2016-01-01

    The extant literature runs short in understanding openness of innovation regarding and the different pathways along which internal and external knowledge resources can be combined. This study proposes a unique typology for outside-in innovations based on two distinct ways of boundary spanning: wh...

  2. Benchmark-problem investigation for seismic response of a large-span cable-stayed bridge based on nonlinear stochastic optimal control%基于非线性随机最优控制的大跨度斜拉桥地震响应 Benchmark 问题研究

    Institute of Scientific and Technical Information of China (English)

    余友熙; 刘中华; 余香林; 王守强

    2016-01-01

    Investigation of vibration control for benchmark problems on large-span,cable-stayed bridge is one of the most important research topics in the current International Symposium on Structural Control.This paper studied second-stage benchmark problems on the Bill Emerson Memorial cable-stayed bridge.In terms of Hamiltonian theory for nonlinear stochastic dynamics and control,the benchmark model under seismic excitations was investigated using MATLAB simulation analysis,based on the stochastic averaging method and stochastic dynamic-programming principle.Comparison of analysis results for optimal forces and performance-evaluation indices between the nonlinear stochastic optimal (NSO) control strategy and the linear quadratic Gaussian (LQG)control strategy revealed that the former control strategy mitigates the seismic response of the cable-stayed bridge more effectively than the latter,thereby enhancing structural dynamic stability and earthquake resistance.In conclusion,the NSO control strategy demonstrates better control effect and presents instructive references and practical significance for vibration control of bridge-engineering applications.%大跨度斜拉桥 Benchmark 问题的振动控制研究是当前国际结构控制研讨会的重要议题之一。以美国 Bill Emerson Memorial 斜拉桥第二阶段 Benchmark 模型为研究对象,在非线性随机动力学与控制的拟哈密顿理论体系框架下,运用基于随机平均法和随机动态规划原理的非线性随机最优(NSO)控制策略,对地震作用下的 Benchmark 模型进行MATLAB 仿真分析。将最优控制力和性能评价指标与线性二次型 Gauss(LQG)控制的计算结果进行对比,得出非线性随机最优控制策略能够更加有效地抑制斜拉桥的地震响应,提高结构的动力稳定性和抗震能力,具有更好的控制效果,对实际桥梁工程的振动控制具有较强的指导意义和适用价值。

  3. 大跨钢桁拱钢-混组合桥面板极限承载力试验%Experiment on Ultimate Bearing Capacity of Steel and Concrete Composite Deck Slab of Long Span Steel Truss Arch Bridge

    Institute of Scientific and Technical Information of China (English)

    卢彭真; 赵人达; 任剑

    2012-01-01

    To assess the ultimate bearing capacity of the steel-concrete composite deck slab subject to highway load, ultimate bearing capacity tests were carried out. According to Saint Venant Principle, by taking the part steel-concrete deck slab in column area with positive and negative bending moments as finite element models of the actual bridge, the study focused on the ultimate bearing capacity of the steel-concrete deck slab in column area with positive and negative bending moments for 2 composite deck slab specimens (model A and model B). The results show that tensile failure has occurred in the concrete slab of model A. The upper and lower flange plates of I beam, web plate and longitudinal reinforcement have not yielded under ultimate load, but steel bottom plate, PBL and lateral reinforcement have yielded before failure. The failure load of model A is 1 750 kN. As for model B, concrete slab has compression failure, PBL has yielded before failure, and the failure load of model B is 2 200 kN. Research results provide reference for design calculation of the ultimate bearing capacity of steel-concrete composite deck slab.%为评估钢一混组合桥面板结构在公路荷栽作用下的极限承载力,对其进行极限承载力性能试验研究。根据圣维南原理,选取正负双向弯矩受力的立柱区部分桥面板作为实桥的有限元分析模型,并试验制作了2个等尺模型试件A和B,用于考察钢一混组合桥面板正负双向弯矩区的极限承载力性能。试验结果表明:模型A混凝土板被拉坏,工.字钢上下翼缘板、腹板以及纵向钢筋始终未屈服,PBL、钢底板以及横向钢筋均在破坏之前屈服,模型A的破坏荷载为1750kN;模型B混凝土板被压坏,PBL在破坏之前屈服,模型B的破坏荷载为2200kN。研究结果可为钢一混组合桥面板极限承栽能力设计计算提供参考。

  4. Span efficiency in hawkmoths

    OpenAIRE

    Henningsson, Per; Bomphrey, Richard J.

    2013-01-01

    Flight in animals is the result of aerodynamic forces generated as flight muscles drive the wings through air. Aerial performance is therefore limited by the efficiency with which momentum is imparted to the air, a property that can be measured using modern techniques. We measured the induced flow fields around six hawkmoth species flying tethered in a wind tunnel to assess span efficiency, ei, and from these measurements, determined the morphological and kinematic characters that predict eff...

  5. Span efficiency in hawkmoths.

    Science.gov (United States)

    Henningsson, Per; Bomphrey, Richard J

    2013-07-06

    Flight in animals is the result of aerodynamic forces generated as flight muscles drive the wings through air. Aerial performance is therefore limited by the efficiency with which momentum is imparted to the air, a property that can be measured using modern techniques. We measured the induced flow fields around six hawkmoth species flying tethered in a wind tunnel to assess span efficiency, ei, and from these measurements, determined the morphological and kinematic characters that predict efficient flight. The species were selected to represent a range in wingspan from 40 to 110 mm (2.75 times) and in mass from 0.2 to 1.5 g (7.5 times) but they were similar in their overall shape and their ecology. From high spatio-temporal resolution quantitative wake images, we extracted time-resolved downwash distributions behind the hawkmoths, calculating instantaneous values of ei throughout the wingbeat cycle as well as multi-wingbeat averages. Span efficiency correlated positively with normalized lift and negatively with advance ratio. Average span efficiencies for the moths ranged from 0.31 to 0.60 showing that the standard generic value of 0.83 used in previous studies of animal flight is not a suitable approximation of aerodynamic performance in insects.

  6. Seismic response study on a multi-span cable-stayed bridge scale model under multi-support excitations. Part II:numerical analysis%多点激励下多跨斜拉桥缩尺模型的地震响应研究.部分2:数值分析

    Institute of Scientific and Technical Information of China (English)

    Rui ZHOU; Zhou-hong ZONG; Xue-yang HUANG; Zhang-hua XIA

    2014-01-01

    In recent years, local component destruction, collapse failure and the control of long-span cable-stayed bridges under strong multi-support excitations have received increasing attention. In this paper, two kinds of nonlinear finite element (FE) models are established to simulate the seismic responses and failure modes of a multi-span cable-stayed bridge scale model under multi-support excitations. One is the single girder model which is used to simulate the seismic response during four wave excita-tions. It can be concluded that the FE analysis results of the scale model are a good fit with those from the shaking table tests. The other one is the explicit dynamic FE model which is used to simulate the collapse and failure mechanisms of the scale model during strong earthquakes. The aggressive failure processes of the scale model under two different types of wave excitations were compared to reproduce the mechanisms in which the bearing at the middle tower failed under the El Centro (EC) wave (4.0 m/s2), and we also observed the connection failure of the cables and towers, and the elements failure of the upper beam in the middle tower, which occurred successively under a Jiangxin (JX) wave (4.0 m/s2). This simulation may be referenced as the basis for the collapse failure of a cable-stayed bridge with a large span during a strong earthquake.%研究目的:通过非线性动力有限元分析,模拟多塔斜拉桥在多点激励下的地震响应以及揭示其在强震下的倒塌破坏模式。创新要点:解决了多塔斜拉桥的非线性动力数值模拟技术,并首次模拟了多塔斜拉桥在强震下的破坏模式。研究方法:首先采用隐式的Newmark-β法求解多点地震激励下的非线性动力方程(图3),随后采用显式的中心差分格式对强震作用下桥梁的倒塌破坏过程进行数值仿真(图4)。重要结论:1.单主梁模型的数值结果可以很好地反映地震模拟振动台

  7. Numerical simulation of highway fire transient space temperature field of bearing elements of long-span suspension bridge%大跨径悬索桥缆索承重构件公路火灾的瞬态空间温度场数值模拟

    Institute of Scientific and Technical Information of China (English)

    李利军; 万祥斌; 董晓明

    2015-01-01

    文章在国内外火灾研究工作的基础上,基于Ingason H平方增长模型,提出了适用于公路桥梁火灾研究的热释放率数学模型;根据建立的公路火灾物理模型,通过数值模拟给出公路火灾下悬索桥主缆、吊索表面温度及热流密度随火灾的发展过程而变化的规律公式,并建立了承重构件瞬态空间温度场。同一火灾场景下,不同直径的吊索可以采用相同的瞬态空间温度场;不同直径的主缆在不同位置具有相同的温度θt2时,可以采用相同的瞬态空间温度场。该研究成果可为今后大跨径悬索桥的抗火设计提供科学依据。%By reviewing and analyzing fire studies conducted at home and abroad ,and based on the Ingason H Square Growth Model ,several kinds of thermal release rate mathematical models are put forward ,which are suitable for the fire studies of highway bridges .Based on the established physical model of highway fire ,the trend of how the surface temperature and heat flux density of main and suspender cables of suspension bridge change with fire situation is observed through the numerical simulation .And the transient space temperature field of bearing elements is established .Under the same conditions of fire accident ,the same transient space temperature field can be applied to suspender cables with different diameters ;the same transient space temper‐ature field can be applied to main cables with different diameters when they have the same θt2 at different places .The research results can provide scientific basis for the fire resistance design of long‐span suspension bridge .

  8. Comparison between field measurement and theoretical analysis results for a long-span suspension bridge's wind-induced vibration responses%某大跨悬索桥风振响应现场实测与理论对比分析

    Institute of Scientific and Technical Information of China (English)

    胡俊; 欧进萍

    2013-01-01

    结合东海某大跨悬索桥健康监测系统,同步实测桥面处风速及加劲梁与吊索风振加速度响应,采用统计方法及频谱分析对结构响应长期实测数据进行分析;探讨结构构件风振响应实际特性;将强风作用下加劲梁响应实测值与抖振分析理论结果进行对比研究.结果表明,加劲梁的RMS响应与垂直桥面平均风速基本呈线性关系,加劲梁响应以低频为主,动力特性随风速增大变化不大;吊索振动主要为高频涡振,迎风侧吊索响应明显高于背风侧吊索响应;由于大跨度悬索桥抖振响应计算及实测过程受复杂与不确定因素影响,理论分析结果明显大于实测值.%Based on the structural health monitoring system installed on a long-span suspension bridge,the simultaneous wind speeds at the bridge deck and the wind-induced acceleration responses of the stiffening girder and hangers were recorded.The actual characteristics of the wind-induced vibrations and the comparison between the theoretical results and the measured responses were discussed.The results indicated that the RMS of acceleration responses of the stiffening girder have a linear relationship with the average wind speeds vertical to the bridge deck; and their dynamic characteristics are stable with increase in wind speed; the dynamic response of the hanger under wind is a higher frequency resonance and the resonance frequency increases with increase in wind speed; the buffeting responses with theoretical analysis are significandy greater than the measured ones,the buffeting analysis still needs more refinements.

  9. Development of cooperative system bridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Zhe; WAN Qi-bai; SHI Lei

    2008-01-01

    Cooperative system bridges comprise several basic structures that act jointly to improve structural characteristics. We delved into the historical development of cooperative system bridges. Cooperative systems are classified as different-load cooperative systems and same-load cooperative systems by distinguishing the modes of load distribution. For different-load cooperation, individual basic structures are at different positions in the direction along bridge axis and carry the loads separately. While for same-load cooperation, all basic structures overlap in geometrical locations and support the entire loads conjointly. The choosing of span ratios between basic structures, the design of connections of different-load cooperative systems were discussed as well as optimizations of relative rigidity for same-load cooperative systems which greatly influence structural characteristics. The general situation and several structural measurements of several cooperative bridges were demonstrated. This information can assist engineers in developing their concepts in cooperative systems and can lead to more efficient and economical cooperative bridges.

  10. Aeroelastic Stability of Suspension Bridges using CFD

    DEFF Research Database (Denmark)

    Stærdahl, Jesper Winther; Sørensen, Niels; Nielsen, Søren R.K.

    2007-01-01

    In recent years large span suspension bridges with very thin and slender profiles have been built without proportional increasing torsional and bending stiffness. As a consequence large deformations at the mid-span can occur with risk of aeroelastic instability and structural failure. Analysis...

  11. Optimum Design of Multilayer Asphalt Surfacing Systems for Orthotropic Steel Deck Bridges

    NARCIS (Netherlands)

    Li, J.

    2015-01-01

    Orthotropic steel decks are widely utilized in long span bridges, movable bridges and shorter span road and rail bridges due to their favourable properties. These properties are low deadweight, large plastic reserves in case of overload and aesthetic advantages. Nowadays, more than 1000 orthotropic

  12. Calculations in bridge aeroelasticity via CFD

    Energy Technology Data Exchange (ETDEWEB)

    Brar, P.S.; Raul, R.; Scanlan, R.H. [Johns Hopkins Univ., Baltimore, MD (United States)

    1996-12-31

    The central focus of the present study is the numerical calculation of flutter derivatives. These aeroelastic coefficients play an important role in determining the stability or instability of long, flexible structures under ambient wind loading. A class of Civil Engineering structures most susceptible to such an instability are long-span bridges of the cable-stayed or suspended-span variety. The disastrous collapse of the Tacoma Narrows suspension bridge in the recent past, due to a flutter instability, has been a big impetus in motivating studies in flutter of bridge decks.

  13. Suspension Bridge Flutter for Girder with Separate Control Flaps

    DEFF Research Database (Denmark)

    Huynh, T.; Thoft-Christensen, Palle

    Active vibration control of long span suspension bridge flutter using separated control flaps (SFSC) has shown to increase effectively the critical wind speed of bridges. In this paper, an SFSC calculation based on modal equations of the vertical and torsional motions of the bridge girder including...

  14. 行波及相干效应对超千米跨度斜拉桥多维多点随机地震响应的影响%The Influence of Traveling Wave and Coherent Effects on Multi-dimensional and Multi-point Random Seismic Response of Super Long Span Cable Stayed Bridge

    Institute of Scientific and Technical Information of China (English)

    范晨阳; 郑史雄; 陈航; 张金

    2016-01-01

    为了研究行波及相干效应对超千米跨度公铁两用斜拉桥地震响应的影响,基于通用有限元软件ANSYS,借助高效的虚拟激励法分别得到考虑两种效应的结构地震响应值,通过对比研究,结果表明:(1)仅考虑行波效应时,在视波速取500 m/s工况下,主梁纵向位移和竖向位移出现最大均方根值,行波效应对主梁纵向位移响应影响最为显著;(2)仅考虑相干效应时,主梁纵向位移和横向位移在部分相干工况下出现最大均方根值,主梁跨中横向位移的均方根值为0.274 m,较一致激励(完全相干)增大了126.4%;(3)两种效应对结构1号边墩、2号辅助墩和3号主塔的不同地震响应的影响程度存在较大差异,需具体响应具体分析。通过各具体工况下的结果对比,得出超大跨度斜拉桥地震响应分析考虑行波和相干效应十分必要的结论。%In order to study the influence of traveling wave and coherent effects on seismic response of the super long span railway double purpose cable stayed bridge, the seismic response of the structures with two effects are obtained with the aid of the efficient virtual excitation method based on the general finite element software ANSYS. The results of the comparative study show that:( 1 ) when only the traveling wave effect is considered, the effect of the traveling wave on the longitudinal displacement of the main beam is the most significant, while the apparent wave velocity of 500 m/s is taken with the maximum root mean square value of both the longitudinal displacement and the vertical displacement of the main beam;( 2 ) when only the coherence effect is considered, the longitudinal displacement and transverse displacement of the main beam appear under partially coherent conditions, the root mean square value of the transverse displacement of the main beam is 0. 274 m, and the uniform excitation ( totally coherent) increases by 126. 4%; ( 3 ) the seismic responses of

  15. Myocardial Bridging

    Directory of Open Access Journals (Sweden)

    Shi-Min Yuan

    2016-02-01

    Full Text Available Abstract Myocardial bridging is rare. Myocardial bridges are most commonly localized in the middle segment of the left anterior descending coronary artery. The anatomic features of the bridges vary significantly. Alterations of the endothelial morphology and the vasoactive agents impact on the progression of atherosclerosis of myocardial bridging. Patients may present with chest pain, myocardial infarction, arrhythmia and even sudden death. Patients who respond poorly to the medical treatment with β-blockers warrant a surgical intervention. Myotomy is a preferred surgical procedure for the symptomatic patients. Coronary stent deployment has been in limited use due to the unsatisfactory long-term results.

  16. Experimental and numerical studies on precise damage localization of a long-span steel truss bridge model%大跨度钢桁桥模型的精细化损伤定位模拟和试验研究

    Institute of Scientific and Technical Information of China (English)

    安永辉; 欧进萍

    2011-01-01

    在役大跨钢桁桥数日众多,其杆件往往较长,所以识别出损伤杆并找出局部损伤所处位置对安全评定和加固尤为重要。针对这一问题,参考我国在役钢桁梁桥,基于健康监测的试验目的和相似理论设计制作了贝雷梁式筒支钢桁桥Benchmark模型。根据其结构形式、具体尺寸,并经试验结果修正,建立了基准Matlab有限元模型。环境激励下,首先隔离一个三角形子结构为研究对象,基于随机损伤定位向量(SDLV)法识别出损伤杆后通过在其上附加传感器的方法来定位局部损伤。其次,由于SDLV法要求桁架待测区间内所有节点均为测点,花费较大而不便于应用。文中还初步探讨了基于部分节点数据的SDLV法的可能性。数值和试验结果均表明,SDLV法不但能识别损伤杆,还能对局部损伤进行精细化定位,效果良好,为进一步探讨基于部分测点的损伤识别奠定了基础。%Large numbers of long-span steel truss bridges with long bars are in service. Therefore, it is imperative for their safety assessment and maintenance to obtain damaged bars and the location of local damage. To solve this problem, a simply supported bailey steel truss bridge Benchmark model for health monitoring was designed and constructed according to the highway and railway bi-purpose steel truss bridges employed in China. Based on structure form and detailed dimensions, a Matlab finite element model was established as the reference model due to the perfect match of the modal parameters with experimental results. Under ambient excitation, a triangular substructure was separated as a research object. Firstly, based on the Stochastic Damage Locating Vector (SDLV) method, the damaged bar was detected and additional sensors were installed on it to identify the local damage. Secondly, conventional SDLV method needs information from all nodes in a truss structure or a substructure of

  17. Seismic response of steel suspension bridge

    Energy Technology Data Exchange (ETDEWEB)

    McCallen, D.B. [Lawrence Livermore National Lab., CA (United States); Astaneh-Asl, A. [California Univ., Berkeley, CA (United States). Dept. of Civil and Environmental Engineering

    1996-11-01

    Performing accurate, realistic numerical simulations of the seismic response of long-span bridges presents a significant challenge to the fields of earthquake engineering and seismology. Suspension bridges in particular represent some of the largest and most important man-made structures and ensuring the seismic integrity of these mega-structures is contingent on accurate estimations of earthquake ground motions and accurate computational simulations of the structure/foundation system response. A cooperative, multi-year research project between the Univ. of California and LLNL was recently initiated to study engineering and seismological issues essential for simulating the response of major structures. Part of this research project is focused on the response of the long-span bridges with the San Francisco-Oakland Bay Bridge serving as a case study. This paper reports on the status of this multi-disciplinary research project with emphasis on the numerical simulation of the transient seismic response of the Bay Bridge.

  18. Field performance of timber bridges. 11, Spearfish Creek stress-laminated box-beam bridge

    Science.gov (United States)

    J. P. Wacker; M. A. Ritter; K. Stanfill-McMillan

    The Spearfish Creek bridge was constructed in 1992 in Spearfish, South Dakota. It is a single-span, stress-laminated, box-beam superstructure. Performance of the bridge is being monitored for 5 years, beginning at installation. This report summarizes results for the first 3-1/2 years of monitoring and includes information on the design, construction, and field...

  19. Field performance of timber bridges. 12, Christian Hollow stress-laminated box-beam bridge

    Science.gov (United States)

    J. P. Wacker; S. C. Catherman; R. G. Winnett

    In January 1992, the Christian Hollow bridge was constructed in Steuben County, New York. The bridge is a single-span, stress-laminated box-beam superstructure that is 9.1 m long, 9.8 m wide, and 502 mm deep (30 ft long, 32 ft wide, and 19-3/4 in. deep). The performance of the bridge was continuously monitored for 28 months, beginning shortly after installation....

  20. Spanning trees crossing few barriers

    NARCIS (Netherlands)

    Asano, T.; Berg, M. de; Cheong, O.; Guibas, L.J.; Snoeyink, J.; Tamaki, H.

    2002-01-01

    We consider the problem of finding low-cost spanning trees for sets of n points in the plane, where the cost of a spanning tree is defined as the total number of intersections of tree edges with a given set of m barriers. We obtain the following results: (i) if the barriers are possibly intersecting

  1. Operational modal analysis of road-rail bridge

    OpenAIRE

    Cardoso M.; Sampaio R. A. C.; de Souza R. M.; Silva E.

    2015-01-01

    In this paper, we describe an Operational Modal Analysis (OMA) of the Bridge over the Tocantins River, a composite road-rail bridge located in the city of Marabá, state of Pará, northern Brazil. The bridge is part of the Carajás Railway, which is used by VALE Company to transport iron ore from “Serra dos Carajás”, the largest mineral reserve of the planet. The bridge has a length of 2310m, being the second longest road-rail bridge in Brazil. The study focused on the bridge central span (with ...

  2. Bridge Management Systems

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper bridge management systems are discussed with special emphasis on management systems for reinforced concrete bridges. Management systems for prestressed concrete bridges, steel bridges, or composite bridges can be developed in a similar way....

  3. Aerodynamic stability of cable-stayed-suspension hybrid bridges

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-jun; SUN Bing-nan

    2005-01-01

    Three-dimensional nonlinear aerodynamic stability analysis was applied to study the aerodynamic stability of a cable-stayed-suspension (CSS) hybrid bridge with main span of 1400 meters, and the effects of some design parameters (such as the cable sag, length of suspension portion, cable plane arrangement, subsidiary piers in side spans, the deck form, etc.) on the aerodynamic stability of the bridge are analytically investigated. The key design parameters, which significantly influence the aerodynamic stability of CSS hybrid bridges, are pointed out, and based on the wind stability the favorable structural system of CSS hybrid bridges is discussed.

  4. Study on structural system of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Xigang; Pei Minshan; Yuan Hong; Xu Liping; Zhu Bin

    2009-01-01

    Sutong Bridge, whose layout is [ (100 + 100 + 300) + 1 088 + ( 300 + 100 + 100) ] m, marks the largest span of cable-stayed bridges in the world. The complex natural condition at the bridge site and the strict requirements for resistance of wind and seismic action make it crucial to choose a favorable structural system to assure the function and safety of the bridge. The comparison among several optional structural systems for Sutong Bridge is illustrated. After detailed analysis is carried out for viscous damper and hydraulic buffer, super liquid viscous damper with additional displacement limitation is designed for the first application in bridge engineering. The parameters for the damper is analyzed and studied and the dampers are installed suecessfuUy after quality tests.

  5. Spanning Tree Based Attribute Clustering

    DEFF Research Database (Denmark)

    Zeng, Yifeng; Jorge, Cordero Hernandez

    2009-01-01

    inconsistent edges from a maximum spanning tree by starting appropriate initial modes, therefore generating stable clusters. It discovers sound clusters through simple graph operations and achieves significant computational savings. We compare the Star Discovery algorithm against earlier attribute clustering...

  6. National Bridge Inventory (NBI) Bridges

    Data.gov (United States)

    Department of Homeland Security — The NBI is a collection of information (database) describing the more than 600,000 of the Nation's bridges located on public roads, including Interstate Highways,...

  7. Implementation and Non-Destructive Evaluation of Composite Structural Shapes in the Tom's Creek Bridge

    OpenAIRE

    Hayes, M. D.; J. Haramis; Lesko, John J.; Cousins, Thomas E.; J.C.Duke; Weyers, Richard E.

    2000-01-01

    A bridge rehabilitation utilizing a hybrid fiber reinforced polymeric composite has been completed in Blacksburg, Virginia. This project involved replacing the superstructure in the Tom's Creek Bridge, a rural short-span traffic bridge with a timber deck and corroded steel girders, with a glue-laminated timber deck on composite girders. In order to verify the bridge design and to address construction issues prior to the rehabilitation, a full-scale mock-up of the bridge was built and tested i...

  8. Spanning quadrangulations of triangulated surfaces

    DEFF Research Database (Denmark)

    Kündgen, André; Thomassen, Carsten

    2017-01-01

    In this paper we study alternating cycles in graphs embedded in a surface. We observe that 4-vertex-colorability of a triangulation on a surface can be expressed in terms of spanninq quadrangulations, and we establish connections between spanning quadrangulations and cycles in the dual graph which...... are noncontractible and alternating with respect to a perfect matching. We show that the dual graph of an Eulerian triangulation of an orientable surface other than the sphere has a perfect matching M and an M-alternating noncontractible cycle. As a consequence, every Eulerian triangulation of the torus has...... a nonbipartite spanning quadrangulation. For an Eulerian triangulation G of the projective plane the situation is different: If the dual graph G∗ is nonbipartite, then G∗ has no noncontractible alternating cycle, and all spanning quadrangulations of G are bipartite. If the dual graph G∗ is bipartite, then it has...

  9. A Distributed Spanning Tree Algorithm

    DEFF Research Database (Denmark)

    Johansen, Karl Erik; Jørgensen, Ulla Lundin; Nielsen, Sven Hauge

    We present a distributed algorithm for constructing a spanning tree for connected undirected graphs. Nodes correspond to processors and edges correspond to two-way channels. Each processor has initially a distinct identity and all processors perform the same algorithm. Computation as well...... as communication is asynchronous. The total number of messages sent during a construction of a spanning tree is at most 2E+3NlogN. The maximal message size is loglogN+log(maxid)+3, where maxid is the maximal processor identity....

  10. A distributed spanning tree algorithm

    DEFF Research Database (Denmark)

    Johansen, Karl Erik; Jørgensen, Ulla Lundin; Nielsen, Svend Hauge

    1988-01-01

    We present a distributed algorithm for constructing a spanning tree for connected undirected graphs. Nodes correspond to processors and edges correspond to two way channels. Each processor has initially a distinct identity and all processors perform the same algorithm. Computation as well...... as communication is asyncronous. The total number of messages sent during a construction of a spanning tree is at most 2E+3NlogN. The maximal message size is loglogN+log(maxid)+3, where maxid is the maximal processor identity....

  11. A Distributed Spanning Tree Algorithm

    DEFF Research Database (Denmark)

    Johansen, Karl Erik; Jørgensen, Ulla Lundin; Nielsen, Sven Hauge

    We present a distributed algorithm for constructing a spanning tree for connected undirected graphs. Nodes correspond to processors and edges correspond to two-way channels. Each processor has initially a distinct identity and all processors perform the same algorithm. Computation as well...... as communication is asynchronous. The total number of messages sent during a construction of a spanning tree is at most 2E+3NlogN. The maximal message size is loglogN+log(maxid)+3, where maxid is the maximal processor identity....

  12. Gust loading on streamlined bridge decks

    DEFF Research Database (Denmark)

    Larose, Guy; Mann, Jakob

    1998-01-01

    The current analytical description of the buffeting action of wind on long-span bridges is based on the strip assumption. However, recent experiments on closed-box girder bridge decks have shown that this assumption is not valid and is the source of an important part of the error margin...... of the analytical prediction methods. In this paper, an analytical model that departs from the strip assumption is used to describe the gust loading on a thin airfoil. A parallel is drawn between the analytical model and direct measurements of gust loading on motionless closed-box girder bridge decks. Empirical...

  13. Bridge Damage Detection Using Weigh-In-Motion Technology

    OpenAIRE

    Cantero, Daniel; González, Arturo

    2015-01-01

    This paper proposes a new level I damage detection technique for short to medium span road bridges using weigh-in-motion (WIM) technology. The technique is based on the input provided by two different WIM systems: (a) a pavement-based WIM station located prior to the bridge (which gives vehicle weight estimates without the influence of the bridge) and (b) a bridge-based WIM system which estimates vehicle weights based on the deformation of the bridge. It is shown that the ratio of estimations...

  14. Bridged graphite oxide materials

    Science.gov (United States)

    Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)

    2010-01-01

    Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.

  15. The Effect of Deck Width Addition Toward Stability of Cable Stayed Bridge: Case Study of Siak Sri Indrapura Bridge, Riau

    Directory of Open Access Journals (Sweden)

    Supriyadi Bambang

    2017-01-01

    Full Text Available An aeroelastic interaction always take places in long-span bridge, i.e. the dynamic relationship between wind forces (aerodynamic and bridge structural motion (dynamics. Wind forces may lead to serviceability and safety problems, and may even cause instability of the whole bridge structure due to the flexibility nature of long span bridge structures.The slimer girder plate will make the structure more unstable as can be seen from the occurrence of lateral deformation. This paper presents the results analysis of cable stayed bridge that has total span of 640 m, two planes configuration of harp-typed hanger cable, the A shape pylons span along 320 m (main span,and side span of 160m. Structural analysis was conducted to determine the optimum ratio between width and spans of cable stayed bridge. The bridge was modeled with various width of 7 to 22 m. Structural modelling was conducted using SAP2000 software to analyze the structural stability of cable stayed bridge under wind load at speed of 35 m/s.The influence of wind loads to the cable stayed bridge stability can be seen based on the bridge deck deformation at the Y-axis (U2, in which for the width of the bridge deck of 7 m, 8 m, 9 m and 10 m, the deformation of U2 are 0.26 m; 0.17 m; 0.12 m and 0.10 m, respectively. Meanwhile, for bridge’s width of 11-22 m, the value of U2 axis deformation is relatively constant between 0.08 m to 0.07 m. This finding suggests that the ratio between width and length of bridge greatly affect the stability of the cable stayed bridge. Cable-stayed bridge, especially for concrete bridge, with two plain system having optimum ratio of width and length show no sign of an aerodynamic instability when fulfills the requirements of B ≥ L / 3.

  16. Modal analysis of cable-stayed UHPC bridge

    Directory of Open Access Journals (Sweden)

    Tej Petr

    2017-01-01

    Full Text Available This paper deals with the dynamic analysis of cable-stayed UHPC bridge over the Vltava river near town Melnik in Czech Republic, Europe. Bridge serves for pedestrians and cyclists. This work aims to familiarize the reader with dynamic calculations carried out and the results obtained, describing the dynamic properties of proposed bridge. The construction of bridge is designed as a cable-stayed structure with prestressed bridge deck consisting of prefabricated UHPC panels and reversed “V” shaped steel pylon with height of approximately 40 meters. The deck is anchored using 24 steel hangers in one row in a steel pylon - 17 ropes in the main span and 7 cables on the other side. Range of the main span is 99.18 meters and the secondary span is 31.9 m. Deck width is 4.5 meters with 3.0 meters passing space. The bridge is designed for the possibility of passage of vehicles weighting up to 3.5 tonnes. Deck panels are made of UHPC with reinforcement. At the edge of the bridge on the side of the shorter span the bridge deck is firmly connected with abutment and on the other deck it is stored using a pair of sliding bearings.

  17. Construction and control technology of the main bridge superstructure of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Zhang Hong; Luo Chenbin; Zhang Yongtao; You Xinpeng

    2009-01-01

    The Sutong Yangtze River Bridge (short as Sutong Bridge) is now the largest span cable-stayed bridge in the world. The construction of the superstructure of the middle bridge covered several stages including erection of the big block girders for the side span, assistant span and tower area, erection of standard girders and closure of the middle span. The big block girders were hoisted by a floating crane, and the standard girders were hoisted by a double crane system on the deck. The pushing assistant method was adopted for the middle span closure construction. Furthermore, key technologies and innovative methods used in the processes of girder erection and cable assemblage in all stages were expatiated systematically. An all-stage self- adaptive geometry control method was used in the construction process. By accurately controlling the unstressed dimensions and shape of all structural components in each step, and realization that the control system and the controlled system adapt to each other, the goal was to make control of the final line shape and inner force of the bridge structure achievable. Two solutions, including GPS based and total station based dynamic geometry monitoring systems, were used to resolve the measure problem under the wide-range of wind-induced vibrations in the long cantilever state. Finally, research on the wind-induced vibration of the superstructure during the construction period was executed. Buffeting response analysis to the longest single and double cantilever states were carried out. The analysis and evaluation of wind resistance safety of the main girders under the longest single cantilever state was made, and corresponding wind resistance measures were suggested. The as-built geometric error and cable force error were controlled in a required design range, and this whole technological achievement can be a benchmark for construction of other large span cable-stayed bridges in the future.

  18. Building Bridges

    DEFF Research Database (Denmark)

    The report Building Bridges adresses the questions why, how and for whom academic audience research has public value, from the different points of view of the four working groups in the COST Action IS0906 Transforming Audiences, Transforming Societies – “New Media Genres, Media Literacy and Trust...... in the Media”, “Audience Interactivity and Participation”, “The Role of Media and ICT Use for Evolving Social Relationships” and “Audience Transformations and Social Integration”. Building Bridges is the result of an ongoing dialogue between the Action and non-academic stakeholders in the field of audience...... Belgrade), Leo Pekkala (Finnish Centre for Media Education and Audiovisual Media/MEKU), Julie Uldam (Network on Civic Engagement and Social Innovation) and Gabriella Velics (Community Media Forum Europe)....

  19. Mathematical bridges

    CERN Document Server

    Andreescu, Titu; Tetiva, Marian

    2017-01-01

    Building bridges between classical results and contemporary nonstandard problems, Mathematical Bridges embraces important topics in analysis and algebra from a problem-solving perspective. Blending old and new techniques, tactics and strategies used in solving challenging mathematical problems, readers will discover numerous genuine mathematical gems throughout that will heighten their appreciation of the inherent beauty of mathematics. Most of the problems are original to the authors and are intertwined in a well-motivated exposition driven by representative examples. The book is structured to assist the reader in formulating and proving conjectures, as well as devising solutions to important mathematical problems by making connections between various concepts and ideas from different areas of mathematics. Instructors and educators teaching problem-solving courses or organizing mathematics clubs, as well as motivated mathematics students from high school juniors to college seniors, will find Mathematical Bri...

  20. Carbon fiber-reinforced polymer strengthening and monitoring of the grondals bridge in Sweden

    DEFF Research Database (Denmark)

    Täljsten, Björn; Hejll, Arvid; James, Gerard

    2007-01-01

    The Grondal Bridge is a large freivorbau bridge (prestressed concrete box bridge), approximately 400 min length with a free span of 120 m. It was opened to tram traffic in the year 2000. Just after opening cracks were noticed in the webs, these cracks have then increased, the size of the largest ...

  1. Exploring boundary-spanning practices among creativity managers

    DEFF Research Database (Denmark)

    Andersen, Poul Houman; Kragh, Hanne

    2015-01-01

    projects across organisational boundaries. Design/methodology/approach – The authors link to previous literature and present findings from a comparative case study of managerial practices for managing creativity projects. Data were collected through interviews, secondary materials, site visits...... and observation. Findings – Three meta-practices used by managers to manage boundary-spanning creative projects are presented: defining the creative space, making space for creativity and acting in the creative space. These practices are detailed in seven case studies of creative projects. Research limitations......-reflection. Originality/value – The authors contribute to research on boundary spanning practices by linking to creativity research, and bridge to research on management and governance in distributed and lessdefined organisations....

  2. Domain-general mechanisms of complex working memory span.

    Science.gov (United States)

    Chein, Jason M; Moore, Adam B; Conway, Andrew R A

    2011-01-01

    A new fMRI complex working memory span paradigm was used to identify brain regions making domain-general contributions to working memory task performance. For both verbal and spatial versions of the task, complex working memory span performance increased the activity in lateral prefrontal, anterior cingulate, and parietal cortices during the Encoding, Maintenance, and Coordination phase of task performance. Meanwhile, overlapping activity in anterior prefrontal and medial temporal lobe regions was associated with both verbal and spatial recall from working memory. These findings help to adjudicate several contested issues regarding the executive mechanisms of working memory, the separability of short-term and working memory in the verbal and spatial domains, and the relative contribution of short-term and long-term memory mechanisms to working memory capacity. The study also provides a vital bridge between psychometric and neuroimaging approaches to working memory, and constrains our understanding of how working memory may contribute to the broader landscape of cognitive performance.

  3. Precast Pearl-Chain concrete arch bridges

    DEFF Research Database (Denmark)

    Halding, Philip Skov; Hertz, Kristian Dahl; Schmidt, Jacob Wittrup

    2015-01-01

    A Pearl-Chain Bridge is a closed-spandrel arch bridge consisting of a number of straight pre-fabricated so called Super-Light Deck elements put together in an arch shape by post-tensioning cables. Several Pearl-Chain arches can be positioned adjacent to each other by a crane to achieve a bridge...... the technology was used. We also study other important components and details in the Pearl-Chain Bridge concept and review the effects of different types of loads. A theoretical case study of a circular 30 m span Pearl-Chain Bridge is presented showing the influence of a number of parameters: The number of post-tensioning......, and gives a large positive bending moment below the load and a smaller negative bending moment in the unloaded side. When the Pearl-Chain Bridge concept is compared to other pre-fabricated arch bridge solutions we find a number of advantages when using Pearl-Chain Bridges: Straight elements, combination...

  4. Operational modal analysis of road-rail bridge

    Directory of Open Access Journals (Sweden)

    Cardoso M.

    2015-01-01

    Full Text Available In this paper, we describe an Operational Modal Analysis (OMA of the Bridge over the Tocantins River, a composite road-rail bridge located in the city of Marabá, state of Pará, northern Brazil. The bridge is part of the Carajás Railway, which is used by VALE Company to transport iron ore from “Serra dos Carajás”, the largest mineral reserve of the planet. The bridge has a length of 2310m, being the second longest road-rail bridge in Brazil. The study focused on the bridge central span (with 77 m of length and two adjacent spans (with 44 m of length. We employed Piezo-electric accelerometers to measure the dynamic response of the bridge under ambient excitation, which consisted of the passage of loaded and unloaded trains, road traffic, wind and river current. For modal identification, to avoid the influence of the train mass over the bridge system, we only considered acceleration signals of road traffic and signals corresponding to intervals after the passage of loaded trains, i.e., the study disregarded the intervals during which the trains were over the monitored spans. We obtained modal parameters through two identification methods: one in the time domain and other in the frequency domain. We also performed a comparative analysis between the experimental modal parameters, and the numerical results obtained with a finite element model provided by a third-part company.

  5. Intercellular bridges in vertebrate gastrulation.

    Directory of Open Access Journals (Sweden)

    Luca Caneparo

    Full Text Available The developing zebrafish embryo has been the subject of many studies of regional patterning, stereotypical cell movements and changes in cell shape. To better study the morphological features of cells during gastrulation, we generated mosaic embryos expressing membrane attached Dendra2 to highlight cellular boundaries. We find that intercellular bridges join a significant fraction of epiblast cells in the zebrafish embryo, reaching several cell diameters in length and spanning across different regions of the developing embryos. These intercellular bridges are distinct from the cellular protrusions previously reported as extending from hypoblast cells (1-2 cellular diameters in length or epiblast cells (which were shorter. Most of the intercellular bridges were formed at pre-gastrula stages by the daughters of a dividing cell maintaining a membrane tether as they move apart after mitosis. These intercellular bridges persist during gastrulation and can mediate the transfer of proteins between distant cells. These findings reveal a surprising feature of the cellular landscape in zebrafish embryos and open new possibilities for cell-cell communication during gastrulation, with implications for modeling, cellular mechanics, and morphogenetic signaling.

  6. 高填土路堤对既有大跨度桥梁桩基的影响分析与监测%Analysis and Field Monitoring on the Effect of High Earth Embankment on the Existing Large Span Bridge Pile foundations

    Institute of Scientific and Technical Information of China (English)

    宋春雨; 季永兴; 孙磊

    2015-01-01

    哈尔滨市松花江北岸滨江大道工程穿越松花江跨江大桥。为减轻路堤填筑对桥桩的影响,基于垂向二维有限元模型及现场监测,研究了土工格栅加筋、钻孔灌注桩隔离及注浆处理等综合措施的可行性,并分析了路堤填筑过程中地基土及桥桩的变形。结果表明:土体加筋、钻孔灌注桩隔离及注浆处理等综合措施可有效减轻路堤填筑对桥桩的影响;路堤填筑对桥桩的影响主要集中在桥墩桩身的上部,桩身下部影响较小;桩基础附加沉降主要由承台上部填土所致,主动区加固措施对减小桥桩的水平位移效果比较明显。研究同时表明,垂向二维有限元模型因桩基简化为板桩墙,使得地层附加应力全部由桩基承担,被动区土层变形的计算结果偏小,桩基变形计算结果偏大。%Bingjiang Avenue is built along the north bank of Songhua River and runs through the Songpu Bridge in Haerbin city ,the provincial capital of Heilongjiang .The high embankment causes additional stresses in the ground layers affecting on the adjacent piles for the bridge abutment .In this paper ,a 2D FEM model was used to analyze the deforma-tions of soil layers and the performances of bridge piles during the construction .The field monitored data of settlements and lateral displacements were reported and discussed .The synthetic implements including geogrid ,bore piles for stress isolation and compaction grouting were studied for their feasibility on controlling the influences of high embankment on the bridge piles ,as well as the deformation of the foundation and the bridge piles .The results of computations and measure-ments in situ can be summarized as follows :the synthetic implements mentioned above can alleviate the influence of em-bankment construction on the adjacent bridge piles ;high embankment mainly affects on the performance of upper part of the piles ,while the lower parts are

  7. Active Control of Long Bridges Using Flaps

    DEFF Research Database (Denmark)

    Hansen, H. I.; Thoft-Christensen, Palle

    The main problem in designing ultra-long span suspension bridges is flutter. A solution to this problem might be to introduce an active flap control system to increase the flutter wind velocity. The investigated flap control system consists of flaps integrated in the bridge girder so each flap...... is the streamlined part of the edge of the girder. Additional aerodynamic derivatives are shown for the flaps and it is shown how methods already developed can be used to estimate the flutter wind velocity for a bridge section with flaps. As an example, the flutter wind velocity is calculated for different flap...... configurations for a bridge section model by using aerodynamic derivatives for a flat plate. The example shows that different flap configurations can either increase or decrease the flutter wind velocity. for optimal flap configurations flutter will not occur....

  8. A bridge to advanced mathematics

    CERN Document Server

    Sentilles, Dennis

    2011-01-01

    This helpful workbook-style ""bridge"" book introduces students to the foundations of advanced mathematics, spanning the gap between a practically oriented calculus sequence and subsequent courses in algebra and analysis with a more theoretical slant. Part 1 focuses on logic and number systems, providing the most basic tools, examples, and motivation for the manner, method, and concerns of higher mathematics. Part 2 covers sets, relations, functions, infinite sets, and mathematical proofs and reasoning. Author Dennis Sentilles also discusses the history and development of mathematics as well a

  9. Application of Large-diameter and Long-span Micro-expansive Pumping

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this article the high strength micro-expansive concrete that has been applied on big-diameter and long-span steel arch bridge is researched. The applications show that the concrete has some merits,such as good fluidity, low bleeding ratio and no segregation, low slump loss, high early strength and high later strength, micro-expansion etc.

  10. Analysis of Local Stress at Transition Sections of Abutments in Large-span Steel-box Handle Basket Arch Bridges%大跨度钢箱提篮拱桥拱脚过渡段局部应力分析

    Institute of Scientific and Technical Information of China (English)

    户东阳; 何旭辉; 秦红禧

    2011-01-01

    以正在修建的某高速铁路提篮拱桥为背景,针对3个拱脚过渡段设计方案,应用大型通用软件ANSYS,分别建立全桥模型和拱脚局部模型,并对3个方案的拱脚过渡段的应力分布进行分析.可供类似桥梁设计施工参考.%Based on the handle basket arc bridge on some expressway under construction as background and aiming at three design plans for transition sections of abutments, this paper establishes full-scale model of the whole bridge and local model of abutment by means of large-scale universal software ANSYS, and analyzes stress distribution of transition sections of abutments in three plans. The analysis of this paper can be a reference for design of similar bridges.

  11. Modelling of nonlinear bridge aerodynamics and aeroelasticity: a convolution based approach

    Directory of Open Access Journals (Sweden)

    Wu T.

    2012-07-01

    Full Text Available Innovative bridge decks exhibit nonlinear behaviour in wind tunnel studies which has placed increasing importance on the nonlinear bridge aerodynamics/aeroelasticity considerations for long-span bridges. The convolution scheme concerning the first-order kernels for linear analysis is reviewed, which is followed by an introduction to higher-order kernels for nonlinear analysis. A numerical example of a longspan suspension bridge is presented that demonstrates the efficacy of the proposed scheme.

  12. 大跨度预应力混凝土连续刚构桥动力特性及P-Δ效应分析%Analysis of the Dynamic Characteristics and P-Δ Effects of Long-Span Continuous Pre-Stressed Concrete Rigid-Frame Bridges

    Institute of Scientific and Technical Information of China (English)

    王宝金

    2011-01-01

    以某已建成的连续刚构桥为研究对象,采用Midas/civil 2010有限元程序,建立连续刚构桥有限元模型,分析了连续刚构桥采用钢筋混凝土双薄壁实心墩、双薄壁空心墩和单柱式空心墩三种截面形式的动力特性和分别在纵向地震和横桥向地震作用下结构的PΔ效应。研究结果表明:三种不同截面类型的桥梁自振频率依次增大,不同的桥墩截面形式使桥梁结构的振型序列发生变化;在三种桥墩截面形式下,考虑P-Δ效应后,对纵向地震响应的影响显著而对横向地震响应的影响较小,但P-Δ效应并不影响桥梁结构的时程曲线趋势。%With a completed continuous rigid-frame bridge as the object of our research,the finite element program Midas/civil 2010 is used to help establish a finite element calculating model for the continuous rigid-frame bridge.The dynamic characteristics and P-Δ effects of the continuous rigid frame bridge respectively with the double thin-walled solid pillars,the double thin-walled hollow pillars and the single-column hollow pillar respectively under the action of the longitudinal earthquake and the bridge-crossing earthquake are analyzed in the paper.The research results show that the self-vibration frequencies of the three kinds of bridges increase in turn.The mode shape sequence changes with the different cross-section types of the pier.With all the three different cross-section types taken into consideration,the influence of the P-Δ effects on the longitudinal seismic response is obvious while the influence of the P-Δ effects on the lateral seismic response is comparatively small.However,the P-Δ effects have no impact on the trend of the time-history curve.

  13. Comparison of aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks

    Science.gov (United States)

    Haque, Md. Naimul; Katsuchi, Hiroshi; Yamada, Hitoshi; Nishio, Mayuko

    2016-07-01

    Aerodynamics of the long-span bridge deck should be well understood for an efficient design of the bridge system. For practical bridges various deck shapes are being recommended and adopted, yet not all of their aerodynamic behaviors are well interpreted. In the present study, a numerical investigation was carried out to explore the aerodynamic characteristics of pentagonal and hexagonal shaped bridge decks. A relative comparison of steady state aerodynamic responses was made and the flow field was critically analyzed for better understanding the aerodynamic responses. It was found that the hexagonal shaped bridge deck has better aerodynamic characteristics as compared to the pentagonal shaped bridge deck.

  14. First-passage probability of the deflection of a cable-stayed bridge under long-term site-specific traffic loading

    OpenAIRE

    Naiwei Lu; Mohammad Noori; Yang Liu

    2017-01-01

    Long-span bridges suffer from higher traffic loads and the simultaneous presence of multiple vehicles, which in conjunction with the steady traffic growth may pose a threat to the bridge safety. This study presents a methodology for first-passage probability evaluation of long-span bridges subject to stochastic heavy traffic loading. Initially, the stochastic heavy traffic loading was simulated based on long-term weigh-in-motion measurements of a highway bridge in China. A computational frame...

  15. Construction of stiffening girder for Akashi straits bridge. Installation with use of latest bridging technology; Akashi kaikyo ohashi hoko keta kasetsu koji. Saishin kakyo gijutsu wo kushishite kasetsu

    Energy Technology Data Exchange (ETDEWEB)

    Oe, S. [Honshu-Shikoku Bridge Authority, Tokyo (Japan)

    1996-05-25

    The Akashi straits bridge is the Kobe-Naruto route of the bridge connecting Honshu and Shikoku; the bridge links Kobe in Hyogo prefecture with Awaji Island and, when completed, it will be a 3-span 2-hinge suspension bridge with the longest center effective span in the world. This report centers on the outline of the construction of stiffening girders for the Akashi straits bridge and especially on the characteristics of the engineering method newly employed. As the method of installing the stiffening girders, an overhang installation of face bars was employed which was a time-tested method. As the installing direction of the side spans, it was decided to install them from the anchorage to the tower. At the beginning, six large block installations were performed. A special balance was developed for the installation of short hanger parts for the purpose of enhancing safety and reduction in the process. A rubber-tired transporting truck was adopted for transporting members of framework on the bridge. GPS survey was used as a method for surveying the configuration. The subject engineering method was based on the construction of suspension bridge stiffening trusses in the past Honshu-Shikoku connecting bridge and reinforced with the improvements as above. Since the bridge is in the middle of construction, a subsequent report will hopefully be made on the actual results of the installation and the spanning after the closure. 8 figs., 2 tabs.

  16. Study on effects of environmental temperature on dynamic characteristics of Taizhou Yangtze River Bridge

    Institute of Scientific and Technical Information of China (English)

    Miao Changqing; Chen Liang; Feng Zhaoxiang

    2011-01-01

    The dynamic characteristics of three-tower and two-span suspension bridge are analyzed at different global temperatures. An equivalent cable inner force method is proposed to consider temperature effects and to study the effects of environmental temperature on dynamic characteristics of Taizhou Yangtze River Bridge. The result demonstrates that the effects of temperature can not be neglected in static or dynamic analysis of Taizhou Yangtze River Bridge. The relationship between temperature and frequency is negative. The effects of temperature should be taken into account in experimental modal analysis of long-span bridges and damage identification.

  17. Wind Tunnel Experiments with Active Control of Bridge Section Model

    DEFF Research Database (Denmark)

    Hansen, Henriette I.; Thoft-Christensen, Palle

    the flutter wind velocity for future ultra-long span suspension bridges. The purpose of the wind tunnel experiments is to investigate the principle to use this active flap control system. The bridge section model used in the experiments is therefore not a model of a specific bridge but it is realistic......This paper describes results of wind tunnel experiments with a bridge section model where movable flaps are integrated in the bridge girder so each flap is the streamlined part of the edge of the girder. This active control flap system is patented by COWIconsult and may be used to increase...... compared with a real bridge. Five flap configurations are investigated during the wind tunnel experiments and depending on the actual flap configuration it is possible to decrease or increase the flutter wind velocity for the model....

  18. Estimation of Curvature Changes for Steel-Concrete Composite Bridge Using Fiber Bragg Grating Sensors

    Directory of Open Access Journals (Sweden)

    Donghoon Kang

    2013-01-01

    Full Text Available This study is focused on the verification of the key idea of a newly developed steel-concrete composite bridge. The key idea of the proposed bridge is to reduce the design moment by applying vertical prestressing force to steel girders, so that a moment distribution of a continuous span bridge is formed in a simple span bridge. For the verification of the key technology, curvature changes of the bridge should be monitored sequentially at every construction stage. A pair of multiplexed FBG sensor arrays is proposed in order to measure curvature changes in this study. They are embedded in a full-scale test bridge and measured local strains, which are finally converted to curvatures. From the result of curvature changes, it is successfully ensured that the key idea of the proposed bridge, expected theoretically, is viable.

  19. Carbon Fibre-reinforced Polymer Strengthening and monitoring of the Gröndals Bridge in Sweden

    DEFF Research Database (Denmark)

    Täljsten, Björn; Hejll, A.; James, G.

    2007-01-01

    The Gröndal Bridge is a large freivorbau bridge (prestressed concrete box bridge), approximately 400 m in length with a free span of 120 m. It was opened to tram traffic in the year 2000. Just after opening cracks were noticed in the webs, these cracks have then increased, the size of the largest...

  20. Performance Assessment of Bridges Using GPS: The Juarez Bridge in Culiacan, Mexico

    Science.gov (United States)

    Vazquez, G. E.; Gaxiola-Camacho, J. R.; Trejo, M.; Echagaray, J.; Guzman, G. M.

    2015-12-01

    Performance assessment of bridges has become very important during recent years. Bridges around the world are aging, leading to the incorporation of efficient, reliable, and economic evaluation procedures. These techniques must assess properly the performance of bridges under several loading conditions in a real manner, representing the physics of the problem. Among several approaches, Global Positioning System (GPS) can be intelligently used for the performance evaluation of bridges. We focused on GPS, since it naturally produces position estimates as compared to seismic instruments that record either velocity or acceleration, and thus require an integration. There are several reasons that make the Juarez Bridge a case of study for evaluation: it is approximately 45 years old, it is a reinforced concrete structure, it connects two significant zones of the city, and its spans is closely to 200 meters long. In addition, thousands of vehicles and pedestrians use the Juarez Bridge every day, which make feasible the GPS performance assessment. Hence, in order to produce optimal position estimates, GPS data were collected during two consecutive hours at three different periods of the day for a whole week (Monday through Sunday), to represent three critical limit states of the bridge (mid-span and end-spans). GPS data were processed using the GAMIT/GLOBK software, considering 1-second sampling rate, 15-degree cutoff angle, ionosphere-free double-differenced (DD) carrier phase method, and precise final orbits disseminated by IGS (International GNSS Service). The displacements obtained from the above discussed procedure are compared with allowable values documented in bridge construction manuals. Reliability theory was used to evaluate the probability of failure of the bridge for the three periods of the day. In addition, a conclusion was made about the most risky day of the week for the use of the Juarez Bridge. It is expected that the results from the proposed research

  1. Research on the special lifting devices for steel box girders of Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Chen Ming; Wu Qihe; Luo Chengbin; Zhou Hanfa

    2009-01-01

    Sutong Bridge is a cable-stayed bridge with a steel box girder and a main span of 1 088 m. The steel box girder of main span includes five portions: back span large unit, large block of pylon, standard girder, back span closure girder and middle span closure girder. Each back span large unit is fabricated by welding several deck segments together in factory, and is erected by floating crane. As navigational clearance of the main bridge is high, the traditional truss lifting device can' t satisfy the requirement of domestic lifting cranes for this kind of lifting height and weight. Hence, a kind of lighter lifting device for the erection of back span large units was accepted for this bridge. In this paper, the design and use of this lifting device is introduced.The upper structure used lifting gantry to install the standard girder segment by cantilever method. Because the bridge's navigation clearance is high, and the girder segment is wide and heavy, the meteorology and hydrology condition of the bridge district is abominable, and the requirements of long cable girder side pull-in, structure and performance propose high request to the lifting gantry. In this paper, the design and use key point of long cable pull-in angle adjustment device integrate into lifting gantry is introduced.

  2. Spatial Mechanical Properties Analysis of Segment No. 0 of Long Span High Speed Railway Pre-stressed Concrete Continued Rigid Frame Bridge%大跨高速铁路连续刚构桥0号块空间力学特性分析

    Institute of Scientific and Technical Information of China (English)

    赵大亮; 苏国明; 王志贤

    2012-01-01

    以某大跨高铁连续刚构桥为研究对象,利用有限元程序ANSYS建立了该桥桥墩0号块的空间有限元计算模型,分析了0号块成桥运营阶段横截面的应力分布规律。结果表明,该桥桥墩0号块各部位均满足规范要求,位于横隔板处的截面,其翼缘板端部应力集中和剪力滞后现象较严重。计算结果已为该桥设计提供了依据,对同类桥梁0号块设计具有参考价值。%Taking a long bridge as an example in the paper, the finite element analysis program ANSYS is applied to estab- lish a three-dimensional solid finite element computational model of segment No. 0, the laws of stress distribution in the cross sections of the box girders are analyzed under operation stage. The results show that the stress of segment No. 0 are in good agreement with the current codes except the manhole part of the diaphragm. The results have been used for the design of the bridge and can be of great benefit for the similar projects.

  3. Bridges in Complex Networks

    CERN Document Server

    Wu, Ang-Kun; Liu, Yang-Yu

    2016-01-01

    A bridge in a graph is an edge whose removal disconnects the graph and increases the number of connected components. We calculate the fraction of bridges in a wide range of real-world networks and their randomized counterparts. We find that real networks typically have more bridges than their completely randomized counterparts, but very similar fraction of bridges as their degree-preserving randomizations. We define a new edge centrality measure, called bridgeness, to differentiate the importance of a bridge in damaging a network. We find that certain real networks have very large average and variance of bridgeness compared to their degree-preserving randomizations and other real networks. Finally, we offer an analytical framework to calculate the bridge fraction and average bridgeness for uncorrelated random networks with arbitrary degree distributions.

  4. Stability of dynamic response of suspension bridges

    Science.gov (United States)

    Capsoni, Antonio; Ardito, Raffaele; Guerrieri, Andrea

    2017-04-01

    The potential occurrence of internal parametric resonance phenomena has been recently indicated as a potential contributory cause of the appearance of critical dynamic states in long-span suspension bridges. At the same time, suspension bridges, in view of their flexibility, are prone to aeroelastic response, such as vortex shedding, torsional divergence and flutter. In this paper, a non-linear dynamic model of a suspension bridge is devised, with the purpose of providing a first attempt toward a unified framework for the study of aeroelastic and internal resonance instabilities. Inspired by the pioneering work of Herrmann and Hauger, the analyses have been based on a linearized formulation that is able to represent the main structural non-linear effects and the coupling given by aerodynamic forces. The results confirm that the interaction between aeroelastic effects and non-linear internal resonance leads to unstable conditions for wind speeds which can be lower than the critical threshold for standard aeroelastic predictions.

  5. Assessment of dynamic properties and stiffness of composite bridges with pavement defects

    Science.gov (United States)

    Kartopol'tsev, Vladimir; Kartopol'tsev, Andrei; Kolmakov, Boris

    2017-01-01

    This paper is aimed at assessing the dynamic properties and stiffness of the reinforced concrete roadway slab under live loads that impact composite bridge girders considering pavement defects. A special attention is paid to the reinforced concrete roadway slab as a transfer member of forced oscillations. The test results obtained for bridges with different spans ranging from 24 to 110 m are presented to assess the behavior of the reinforced concrete roadway slab and the dynamic stiffness of bridge span allowed for the pavement defects. Dynamic tests are carried out under controlled and random loads that simulate live load interaction with the span and the pavement with defects. The differential equations are presented for vertical oscillations of spans, pavement defect parameter, Eigen frequency and others. As a result of the experimental research the equation is derived to ascertain the dynamic stiffness of the vehicle-span system.

  6. A Highly Accurate and Efficient Analytical Approach to Bridge Deck Free Vibration Analysis

    Directory of Open Access Journals (Sweden)

    D.J. Gorman

    2000-01-01

    Full Text Available The superposition method is employed to obtain an accurate analytical type solution for the free vibration frequencies and mode shapes of multi-span bridge decks. Free edge conditions are imposed on the long edges running in the direction of the deck. Inter-span support is of the simple (knife-edge type. The analysis is valid regardless of the number of spans or their individual lengths. Exact agreement is found when computed results are compared with known eigenvalues for bridge decks with all spans of equal length. Mode shapes and eigenvalues are presented for typical bridge decks of three and four span lengths. In each case torsional and non-torsional modes are studied.

  7. Optimization of Dead Load State in Earth-Anchored Cable-Stayed Bridges

    Institute of Scientific and Technical Information of China (English)

    Bin Sun∗; Rucheng Xiao

    2015-01-01

    In order to determine the reasonable completed dead load state in earth⁃anchored cable⁃stayed bridges, a practical method is proposed. The method is based on the rigidly supported continuous beam method and the feasible zone method, emphasizing on the mutual effect between the self⁃anchored structural parts and the earth⁃anchored ones. Three cable⁃stayed bridge models are designed with the main spans of 1 400 m, including a partially earth⁃anchored cable⁃stayed bridge, a cable⁃stayed⁃suspension bridge and a fully self⁃anchored cable⁃stayed bridge, in which the C50 concrete and Q345 steel are adopted. The partially earth⁃anchored cable⁃stayed bridge and the cable⁃stayed⁃suspension bridge secure lower compressive force in the girder than the fully self⁃anchored cable⁃stayed bridge by 25 percent at least. The same is for the material consumption of the whole bridge. Furthermore, the anchor volume is more than 20% lower in the partially earth⁃anchored cable⁃stayed bridge than that in the cable⁃stayed⁃suspension bridge. Consequently, the practical span of cable⁃stayed bridges can be accordingly extended.

  8. Spans in 2-Categories: A monoidal tricategory

    CERN Document Server

    Hoffnung, Alexander E

    2011-01-01

    We present Trimble's definition of a tetracategory and prove that the spans in (strict) 2-categories with certain limits have the structure of a monoidal tricategory, defined as a one-object tetracategory. We recall some notions of limits in 2-categories for use in the construction of the monoidal tricategory of spans.

  9. Node degree distribution in spanning trees

    Science.gov (United States)

    Pozrikidis, C.

    2016-03-01

    A method is presented for computing the number of spanning trees involving one link or a specified group of links, and excluding another link or a specified group of links, in a network described by a simple graph in terms of derivatives of the spanning-tree generating function defined with respect to the eigenvalues of the Kirchhoff (weighted Laplacian) matrix. The method is applied to deduce the node degree distribution in a complete or randomized set of spanning trees of an arbitrary network. An important feature of the proposed method is that the explicit construction of spanning trees is not required. It is shown that the node degree distribution in the spanning trees of the complete network is described by the binomial distribution. Numerical results are presented for the node degree distribution in square, triangular, and honeycomb lattices.

  10. Full-arch milled titanium implant bridge: technical report.

    Science.gov (United States)

    Peché, Wendy-Ann; Van Vuuren, Ludwig Jansen; Park, Chae

    2011-09-01

    The manufacturing of full-arch fixed implant-supported bridges with the use of the traditional lost wax technique remains a technical challenge. Distortion of the alloy during casting and subsequent heating cycles during porcelain build-up causes numerous problems. Fracturing of porcelain on large restorations is difficult and costly to restore. The fitting problems can be eliminated by utilising CAD/CAM technology in the manufacturing of long-span or full-arch titanium bridges. Repair of damaged porcelain can be simplified with the use of discrete, individually-removable crowns on the bridge.

  11. Aerodynamic stability of cable-stayed bridges under erection

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xin-jun; SUN Bing-nan; XIANG Hai-fan

    2005-01-01

    In this work, nonlinear multimode aerodynamic analysis of the Jingsha Bridge under erection over the Yangtze River is conducted, and the evolutions of structural dynamic characteristics and the aerodynamic stability with erection are numerically generated. Instead of the simplified method, nonlinear multimode aerodynamic analysis is suggested to predict the aerodynamic stability of cable-stayed bridges under erection. The analysis showed that the aerodynamic stability maximizes at the relatively early stages, and decreases as the erection proceeds. The removal of the temporary piers in side spans and linking of the main girder to the anchor piers have important influence on the dynamic characteristics and aerodynamic stability of cable-stayed bridges under erection.

  12. Expected damages of retrofitted bridges with RC jacketing

    Science.gov (United States)

    Montes, O.; Jara, J. M.; Jara, M.; Olmos, B. A.

    2015-07-01

    The bridge infrastructure in many countries of the world consists of medium span length structures built several decades ago and designed for very low seismic forces. Many of them are reinforced concrete structures that according to the current code regulations have to be rehabilitated to increase their seismic capacity. One way to reduce the vulnerability of the bridges is by using retrofitting techniques that increase the strength of the structure or by incorporating devices to reduce the seismic demand. One of the most common retrofit techniques of the bridges substructures is the use of RC jacketing; this research assesses the expected damages of seismically deficient medium length highway bridges retrofitted with reinforced concrete jacketing, by conducting a parametric study. We select a suite of twenty accelerograms of subduction earthquakes recorded close to the Pacific Coast in Mexico. The original structures consist of five 30 m span simple supported bridges with five pier heights of 5 m, 10 m, 15 m 20 and 25 m and the analyses include three different jacket thickness and three steel ratios. The bridges were subjected to the seismic records and non-linear time history analyses were carried out by using the OpenSEEs Plataform. Results allow selecting the reinforced concrete jacketing that better improves the expected seismic behavior of the bridge models.

  13. Analysis of resonance mechanism and conditions of train bridge system

    Science.gov (United States)

    Xia, H.; Zhang, N.; Guo, W. W.

    2006-11-01

    In this paper, the resonance mechanism and conditions of train-bridge system are investigated through theoretical derivations, numerical simulations and experimental data analyses. The resonant responses of the bridge induced by moving trains are classified into three types according to different resonance mechanisms: the first is related to the periodical actions of moving load series of the vertical weights, lateral centrifugal and wind forces of vehicles; the second is induced by the loading rate of moving load series of vehicles; the third is owing to the periodically loading of the swing forces of the train vehicles excited by track irregularities and wheel hunting movements. The vehicle resonance is induced by the periodical action of regular arrangement of bridge spans and their deflections. The resonant conditions are proposed and the corresponding resonant train speeds are determined. The application scopes of resonance conditions are discussed. The resonance of the train-bridge system is affected by the span, total length, lateral and vertical stiffness of the bridge, the compositions of the train, and the axle arrangements and natural frequencies of the vehicles. The resonant train speeds for some bridges are estimated and are compared with the critical train speeds obtained from the dynamic simulation of train-bridge interaction model or from the field measurements.

  14. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  15. Ambient Modal Testing of the Vestvej Bridge using Random Decrement

    DEFF Research Database (Denmark)

    Asmussen, J. C.; Brincker, Rune; Rytter, A.

    1998-01-01

    This paper presents an ambient vibration study of the Vestvej Bridge. The bridge is a typically Danish two-span concrete bridge which crosses a highway. The purpose of the study is to perform a pre-investigation of the dynamic behavior to obtain information for the design of a demonstration project...... concerning application of vibration based inspection of bridges. The data analysis process of ambient vribration testing of bridges has traditionally been based on auto and cross spectral densities estimated using an FFT algorithm. In the pre-analysis state the spectral densities are all averaged to obtain...... the averaged spectral densities(ASD). From the ASD the eigenfrequencies of the structure can be identified. This information can be used in the main analysis, where alle modal parameters are extracted from the spectral densities. Due to long cabling and low response levels (small ambient loads) the response...

  16. Anthropogenic sources stimulate resonance of a natural rock bridge

    Science.gov (United States)

    Moore, Jeffrey R.; Thorne, Michael S.; Koper, Keith D.; Wood, John R.; Goddard, Kyler; Burlacu, Relu; Doyle, Sarah; Stanfield, Erik; White, Benjamin

    2016-09-01

    The natural modes of vibration of bedrock landforms, as well as the sources and effects of stimulated resonance remain poorly understood. Here we show that seismic energy created by an induced earthquake and an artificial reservoir has spectral content coincident with the natural modes of vibration of a prominent rock bridge. We measured the resonant frequencies of Rainbow Bridge, Utah using data from two broadband seismometers placed on the span, and identified eight distinct vibrational modes between 1 and 6 Hz. A distant, induced earthquake produced local ground motion rich in 1 Hz energy, stimulating a 20 dB increase in measured power at the bridge's fundamental mode. Moreover, we establish that wave action on Lake Powell, an artificial reservoir, generates microseismic energy with peak power ~1 Hz, also exciting resonance of Rainbow Bridge. These anthropogenic sources represent relatively new energy input for the bridge with unknown consequences for structural fatigue.

  17. Statistical Analysis of Ship Collisions with Bridges in China Waterway

    Institute of Scientific and Technical Information of China (English)

    DAI Tong-yu; NIE Wu; LIU Ying-jie; WANG Li-ping

    2002-01-01

    Having carried out investigations on ship collision accidents with bridges in waterway in China, a database of ship collision with bridge (SCB) is developed in this paper. It includes detailed information about more than 200 accidents near ship's waterways in the last four decades, in which ships collided with the bridges. Based on the information a statistical analysis is presented tentatively. The increase in frequency of ship collision with bridges appears, and the accident quantity of the barge system is more than that of single ship. The main reason of all the factors for ship collision with bridge is the human errors, which takes up 70%. The quantity of the accidents happened during flooding period shows over 3~6 times compared with the period from March to June in a year. The probability follows the normal distribution according to statistical analysis. Visibility, span between piers also have an effect on the frequency of the accidents.

  18. Strengthening of a railway bridge with NSMR and CFRP tubes

    DEFF Research Database (Denmark)

    Täljsten, Björn; Bennitz, Anders; Danielsson, Georg

    2008-01-01

    Strengthening of structures with CFRP is today considered an accepted method to upgrade concrete structures. In this paper two different CFRP strengthening systems are combined to give extended service life to a Swedish double-trough-double-track railway bridge, constructed in concrete with a 10...... meter span. One system is the reliable NSMR (Near Surface Mounted Reinforcement) system while the other one is new; intended to strengthen the interior of a concrete structure, and the other system uses CFRP tubes integrated in drilled holes in the bridge. Both systems are used to increase tensile...... flexural strength of the slab transverse to the tracks. NSMR bars are positioned in the concrete cover on the underside of the bridge, while the new system is inserted in holes drilled through the bridge, in the cross direction and located in the upper part of the bridge slab. In connection...

  19. Computer modeling of road bridge for simulation moving load

    Directory of Open Access Journals (Sweden)

    Miličić Ilija M.

    2016-01-01

    Full Text Available In this paper is shown computational modelling one span road structures truss bridge with the roadway on the upper belt of. Calculation models were treated as planar and spatial girders made up of 1D finite elements with applications for CAA: Tower and Bridge Designer 2016 (2nd Edition. The conducted computer simulations results are obtained for each comparison of the impact of moving load according to the recommendations of the two standards SRPS and AASHATO. Therefore, it is a variant of the bridge structure modeling application that provides Bridge Designer 2016 (2nd Edition identical modeled in an environment of Tower. As important information for the selection of a computer applications point out that the application Bridge Designer 2016 (2nd Edition we arent unable to treat the impacts moving load model under national standard - V600. .

  20. Computation simulation of the nonlinear response of suspension bridges

    Energy Technology Data Exchange (ETDEWEB)

    McCallen, D.B.; Astaneh-Asl, A.

    1997-10-01

    Accurate computational simulation of the dynamic response of long- span bridges presents one of the greatest challenges facing the earthquake engineering community The size of these structures, in terms of physical dimensions and number of main load bearing members, makes computational simulation of transient response an arduous task. Discretization of a large bridge with general purpose finite element software often results in a computational model of such size that excessive computational effort is required for three dimensional nonlinear analyses. The aim of the current study was the development of efficient, computationally based methodologies for the nonlinear analysis of cable supported bridge systems which would allow accurate characterization of a bridge with a relatively small number of degrees of freedom. This work has lead to the development of a special purpose software program for the nonlinear analysis of cable supported bridges and the methodologies and software are described and illustrated in this paper.

  1. Numerical Modelling of Rain-Wind-Induced Vibration: Erasmus Bridge, Rotterdam

    NARCIS (Netherlands)

    Geurts, C.; Vrouwenvelder, T.; Staalduinen, P.C. van; Reusink, J.

    1998-01-01

    Shortly after completion, the main span cables of the Erasmus Bridge in Rotterdam showed aerodynamic instabilities with large amplitudes. These instabilities were recognised as rain-wind-induced vibrations. Temporary measures were installed on the bridge, and a year later, tuned hydraulic dampers we

  2. Demonstration and Validation of a Composite Grid Reinforcement System for Bridge Decks

    Science.gov (United States)

    2016-09-01

    forced concrete bridge decks. Gridform consists of two layers of pultruded grating members that are separated by FRP shear connectors with nylon bolts...span of the bridge. Two ground wires were installed for redundancy. Meas- urements from each ground should theoretically be identical. An Extech 540

  3. Prediction of Fatigue Life of a Continuous Bridge Girder Based on Vehicle Induced Stress History

    Directory of Open Access Journals (Sweden)

    V.G. Rao

    2003-01-01

    Full Text Available The fatigue damage assessment of bridge components by conducting a full scale fatigue testing is often prohibitive. A need, therefore, exists to estimate the fatigue damage in bridge components by a simulation of bridge-vehicle interaction dynamics due to the action of the actual traffic. In the present paper, a systematic method has been outlined to find the fatigue damage in the continuous bridge girder based on stress range frequency histogram and fatigue strength parameters of the bridge materials. Vehicle induced time history of maximum flexural stresses has been obtained by Monte Carlo simulation process and utilized to develop the stress range frequency histogram taking into consideration of the annual traffic volume. The linear damage accumulation theory is then applied to calculate cumulative damage index and fatigue life of the bridge. Effect of the bridge span, pavement condition, increase of vehicle operating speed, weight and suspension characteristics on fatigue life of the bridge have been examined.

  4. Natural vibration dynamics of Rainbow Bridge, Utah

    Science.gov (United States)

    Moore, J. R.; Thorne, M. S.; Wood, J. R.; Doyle, S.; Stanfield, E.; White, B.

    2015-12-01

    We measured resonant frequencies of Rainbow Bridge, Utah, one of the world's longest rock spans, during a field experiment recording ambient vibration data. Measurements were generated over 20 hours on March 23-24, 2015 using two broadband three-component seismometers placed on the bridge, and compared to concurrent data from nearby reference stations 20 and 220 m distant. We identified seven distinct modes of vibration for Rainbow Bridge between 1 and 6 Hz. Data for each resonant frequency was then analyzed to determine the frequency-dependent polarization vector in an attempt to clarify mode shapes; e.g. the fundamental mode represents out-of-plane horizontal flexure. We compared experimental data to results of 3D numerical modal analysis, using a new photogrammetric model of Rainbow Bridge generated in this study imported into COMSOL Multiphysics. Results compare well with measured data for seven of the first eight modeled modes, matching vibrational frequencies and polarization orientations generally within 10%. Only predicted mode 6 was not explicitly apparent in our experimental data. Large site-to-reference spectral ratios resolved from experimental data indicate high amplification on the bridge as compared to nearby bedrock.

  5. Bridges in the random-cluster model

    Directory of Open Access Journals (Sweden)

    Eren Metin Elçi

    2016-02-01

    Full Text Available The random-cluster model, a correlated bond percolation model, unifies a range of important models of statistical mechanics in one description, including independent bond percolation, the Potts model and uniform spanning trees. By introducing a classification of edges based on their relevance to the connectivity we study the stability of clusters in this model. We prove several exact relations for general graphs that allow us to derive unambiguously the finite-size scaling behavior of the density of bridges and non-bridges. For percolation, we are also able to characterize the point for which clusters become maximally fragile and show that it is connected to the concept of the bridge load. Combining our exact treatment with further results from conformal field theory, we uncover a surprising behavior of the (normalized variance of the number of (non-bridges, showing that it diverges in two dimensions below the value 4cos2⁡(π/3=0.2315891⋯ of the cluster coupling q. Finally, we show that a partial or complete pruning of bridges from clusters enables estimates of the backbone fractal dimension that are much less encumbered by finite-size corrections than more conventional approaches.

  6. The Namibia bridge management system: a tool for preservation of structures on the road network

    CSIR Research Space (South Africa)

    Roux, MP

    2010-10-01

    Full Text Available for the management of 6 200 km of paved roads and 35 900 km of unpaved roads, which includes 1 430 bridges and major culverts (>3m span length) and 1 290 lesser culverts (<3 m span). In 2001, the NRA embarked on a project to upgrade their existing BMS, which...

  7. Signal enhancement with variable span linear filters

    CERN Document Server

    Benesty, Jacob; Jensen, Jesper R

    2016-01-01

    This book introduces readers to the novel concept of variable span speech enhancement filters, and demonstrates how it can be used for effective noise reduction in various ways. Further, the book provides the accompanying Matlab code, allowing readers to easily implement the main ideas discussed. Variable span filters combine the ideas of optimal linear filters with those of subspace methods, as they involve the joint diagonalization of the correlation matrices of the desired signal and the noise. The book shows how some well-known filter designs, e.g. the minimum distortion, maximum signal-to-noise ratio, Wiener, and tradeoff filters (including their new generalizations) can be obtained using the variable span filter framework. It then illustrates how the variable span filters can be applied in various contexts, namely in single-channel STFT-based enhancement, in multichannel enhancement in both the time and STFT domains, and, lastly, in time-domain binaural enhancement. In these contexts, the properties of ...

  8. Signal Enhancement with Variable Span Linear Filters

    DEFF Research Database (Denmark)

    Benesty, Jacob; Christensen, Mads Græsbøll; Jensen, Jesper Rindom

    -to-noise ratio, Wiener, and tradeoff filters (including their new generalizations) can be obtained using the variable span filter framework. It then illustrates how the variable span filters can be applied in various contexts, namely in single-channel STFT-based enhancement, in multichannel enhancement in both......This book introduces readers to the novel concept of variable span speech enhancement filters, and demonstrates how it can be used for effective noise reduction in various ways. Further, the book provides the accompanying Matlab code, allowing readers to easily implement the main ideas discussed....... Variable span filters combine the ideas of optimal linear filters with those of subspace methods, as they involve the joint diagonalization of the correlation matrices of the desired signal and the noise. The book shows how some well-known filter designs, e.g. the minimum distortion, maximum signal...

  9. Trees, Tight-Spans and Point Configuration

    CERN Document Server

    Herrmann, Sven

    2011-01-01

    Tight-spans of metrics were first introduced by Isbell in 1964 and rediscovered and studied by others, most notably by Dress who gave them this name. Subsequently, it was found that tight-spans could be defined for more general maps, such as directed metrics and distances, and more recently for diversities. In this paper, we show that all of these tight-spans can be defined in terms of point configurations. This provides a useful way in which to study these objects in a unified and systematic way. We also show that by using point configurations we can recover results concerning one-dimensional tight-spans for all of the maps we consider, as well as extend these and other results to more general maps such as symmetric and unsymmetric maps.

  10. Evaluating the efficiency of shortcut span protection

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Dittmann, Lars; Berger, Michael Stübert

    2010-01-01

    This paper presents a comparison of various recovery methods in terms of capacity efficiency with the underlying aim of reducing control plane load. In particular, a method where recovery requests are bundled towards the destination (Shortcut Span Protection) is evaluated can compared against...... traditional recovery methods. The optimization model is presented and our simulation results show that Shortcut Span Protection uses more capacity than the unbundled related methods, but this is compensated by easier control and management of the recovery actions....

  11. Evaluating the efficiency of shortcut span protection

    DEFF Research Database (Denmark)

    Ruepp, Sarah Renée; Dittmann, Lars; Berger, Michael Stübert;

    2010-01-01

    This paper presents a comparison of various recovery methods in terms of capacity efficiency with the underlying aim of reducing control plane load. In particular, a method where recovery requests are bundled towards the destination (Shortcut Span Protection) is evaluated can compared against...... traditional recovery methods. The optimization model is presented and our simulation results show that Shortcut Span Protection uses more capacity than the unbundled related methods, but this is compensated by easier control and management of the recovery actions....

  12. Social network sampling using spanning trees

    Science.gov (United States)

    Jalali, Zeinab S.; Rezvanian, Alireza; Meybodi, Mohammad Reza

    2016-12-01

    Due to the large scales and limitations in accessing most online social networks, it is hard or infeasible to directly access them in a reasonable amount of time for studying and analysis. Hence, network sampling has emerged as a suitable technique to study and analyze real networks. The main goal of sampling online social networks is constructing a small scale sampled network which preserves the most important properties of the original network. In this paper, we propose two sampling algorithms for sampling online social networks using spanning trees. The first proposed sampling algorithm finds several spanning trees from randomly chosen starting nodes; then the edges in these spanning trees are ranked according to the number of times that each edge has appeared in the set of found spanning trees in the given network. The sampled network is then constructed as a sub-graph of the original network which contains a fraction of nodes that are incident on highly ranked edges. In order to avoid traversing the entire network, the second sampling algorithm is proposed using partial spanning trees. The second sampling algorithm is similar to the first algorithm except that it uses partial spanning trees. Several experiments are conducted to examine the performance of the proposed sampling algorithms on well-known real networks. The obtained results in comparison with other popular sampling methods demonstrate the efficiency of the proposed sampling algorithms in terms of Kolmogorov-Smirnov distance (KSD), skew divergence distance (SDD) and normalized distance (ND).

  13. Wind Resistant Design of Bridges in Japan Developments and Practices

    CERN Document Server

    Fujino, Yozo; Tanaka, Hiroshi

    2012-01-01

    For long-span bridges, wind action is a dominant factor in their safety and serviceability. A large number of long-span bridges have been built in Japan over the past 30 years, and tremendous amounts of research and technical development have been accomplished in wind resistant design. This book is a compilation of the results of active research and development. Wind resistant design standards generated in Japan are described in the first few chapters. Then comes information such as design wind speed, structural damping, wind tunnel tests, and analyses, which provide the basis of the design standards. Wind-induced vibrations and their control of girders, towers, cables, and other features are explained with examples of field measurements. Comprehensive listings of Japanese experience in vibration control are also presented. Because achieving particularly dynamic safety against wind is still not an easy task, these data and information will be valuable assets for the wind-engineering and bridge-engineering com...

  14. Evaluation of frequency spectrum and main oscillation modes of box type multiple cross sections spans

    Directory of Open Access Journals (Sweden)

    Sokolov Oleg Leonidovich

    2014-05-01

    Full Text Available From the viewpoint of mechanics the box span of trestle bridges is non-diaphragm prismatic shell of multiple cross section of average length. Though many problems of static analysis of such structures have been solved, the development of analytical methods of calculating non-diaphragm box type structures on the vibration is an urgent task. The presented method for analysis of free vibration of non-diaphragm spans of box trestle bridges of multiple cross sections is based on the variation theory of prismatic shells of average length by V.Z. Vlasov. In this method the discrete-continuum design scheme, in which the mass of the structure is reduced to its nodal lines, is used. Equations of free vibration are variation equations and represent the work of internal and external forces in the possible displacements. The possible displacements are determined by the static approximation. The order frequency equation, obtained by solving the equation system of free vibration, coincides with the number of the vertical walls of the box span. For a split design scheme span the frequency equation is algebraic, and its components are calculated in analytical formulas. The method is illustrated by free vibrations of non-diaphragm box spans with four cross sections. As a result, the solution frequency spectrum and modes of vibration were defined. The advantage of the presented method of calculation is that the components of the frequency equation are calculated in analytical formulas. This method helps to study free vibration non-diaphragm box spans of multiple cross sections depending on changes in the design parameters. Application of this method will reduce the time and improve the design quality, and also monitor the results of structures analysis prepared with the help of computer complex.

  15. Application of Gliding Scaffold System In Cable-Stayed Bridge Construction

    Institute of Scientific and Technical Information of China (English)

    YU Bao-chu; ZHANG Zhe; Chang Fu-ping

    2005-01-01

    Gonghe bridge is a double level cable-stayed concrete bridge with a single-cable-plane of single cable tower. Its span is 114+120 m and a whole length of 236 m. The gliding scaffold equipment is used for the first time in the long span cable-stayed bridge construction to reduce the construction time limit. In the process of construction, to make sure a safe connection among concrete objects with different ages, the single-supporting and single-suspension system is adopted before the concrete pouring. While the double-supporting and single-suspension system is applied after concrete pouring. These construction systems with gliding scaffold equipment are first introduced in long span cable-stayed bridge and presented in detail[1]. The practice shows that these gliding scaffold systems have many advantages over the traditional ones.

  16. APPLICATION OF ULTRA-HIGH PERFORMANCE CONCRETE TO PEDESTRIAN CABLE-STAYED BRIDGES

    Directory of Open Access Journals (Sweden)

    CHI-DONG LEE

    2013-06-01

    Full Text Available The use of ultra-high performance concrete (UHPC, which enables reducing the cross sectional dimension of the structures due to its high strength, is expected in the construction of the super-long span bridges. Unlike conventional concrete, UHPC experiences less variation of material properties such as creep and drying shrinkage and can reduce uncertainties in predicting time-dependent behavior over the long term. This study describes UHPC’s material characteristics and benefits when applied to super-long span bridges. A UHPC girder pedestrian cable-stayed bridge was designed and successfully constructed. The UHPC reduced the deflections in both the short and long term. The cost analysis demonstrates a highly competitive price for UHPC. This study indicates that UHPC has a strong potential for application in the super-long span bridges.

  17. A simplified fragility analysis of fan type cable stayed bridges

    Institute of Scientific and Technical Information of China (English)

    R. A. Khan; T. K. Datta; S. Ahmad

    2005-01-01

    A simplified fragility analysis of fan type cable stayed bridges using Probabilistic Risk Analysis (PRA)procedure is presented for determining their failure probability under random ground motion. Seismic input to the bridge support is considered to be a risk consistent response spectrum which is obtained from a separate analysis. For the response analysis, the bridge deck is modeled as a beam supported on springs at different points. The stiffnesses of the springs are determined by a separate 2D static analysis of cable-tower-deck system. The analysis provides a coupled stiffness matrix for the spring system. A continuum method of analysis using dynamic stiffness is used to determine the dynamic properties of the bridges .The response of the bridge deck is obtained by the response spectrum method of analysis as applied to multidegree of freedom system which duly takes into account the quasi - static component of bridge deck vibration. The fragility analysis includes uncertainties arising due to the variation in ground motion, material property, modeling, method of analysis,ductility factor and damage concentration effect. Probability of failure of the bridge deck is determined by the First Order Second Moment (FOSM) method of reliability. A three span double plane symmetrical fan type cable stayed bridge of total span 689 m, is used as an illustrative example. The fragility curves for the bridge deck failure are obtained under a number of parametric variations. Some of the important conclusions of the study indicate that (i) not only vertical component but also the horizontal component of ground motion has considerable effect on the probability of failure; (ii) ground motion with no time lag between support excitations provides a smaller probability of failure as compared to ground motion with very large time lag between support excitation; and (iii) probability of failure may considerably increase for soft soil condition.

  18. Effect of vehicle weight on natural frequencies of bridges measured from traffic-induced vibration

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    Recently, ambient vibration test (AVT) is widely used to estimate dynamic characteristics of large civil structures. Dynamic characteristics can be affected by various environmental factors such as humidity, intensity of wind, and temperature. Besides these environmental conditions, the mass of vehicles may change the measured values when traffic-induced vibration is used as a source of AVT for bridges. The effect of vehicle mass on dynamic characteristics is investigated through traffic-induced vibration tests on three bridges; (1) three-span suspension bridge (128m+404m+128m), (2) five-span continuous steel box girder bridge (59m+3@95m+59m), (3) simply supported plate girder bridge (46m). Acceleration histories of each measurement location under normal traffic are recorded for 30 minutes at field. These recorded histories are divided into individual vibrations and are combined into two groups according to the level of vibration; one by heavy vehicles such as trucks and buses and the other by light vehicles such as passenger cars. Separate processing of the two groups of signals shows that, for the middle and long-span bridges, the difference can be hardly detected, but, for the short span bridges whose mass is relatively small, the measured natural frequencies can change up to 5.4%.

  19. Semiconductor bridge (SCB) detonator

    Science.gov (United States)

    Bickes, Jr., Robert W.; Grubelich, Mark C.

    1999-01-01

    The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.

  20. Bridging the Gap

    OpenAIRE

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska; Murdock, Karen; Schmidt, Iben Julie

    2015-01-01

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures. Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ve...

  1. Bridging the Gap

    DEFF Research Database (Denmark)

    Kramer Overgaard, Majken; Broeng, Jes; Jensen, Monika Luniewska;

    Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures.......Bridging the Gap (BtG) is a 2-year project funded by The Danish Industry Foundation. The goal of Bridging the Gap has been to create a new innovation model which will increase the rate at which Danish universities can spinout new technology ventures....

  2. Bridge Condition Assessment based on Vibration Responses of Passenger Vehicle

    Science.gov (United States)

    Miyamoto, Ayaho; Yabe, Akito

    2011-07-01

    In this paper, we propose a new method of assessing the condition of existing short- and medium-span reinforced/prestressed concrete bridges based on vibration monitoring data obtained from a public bus. This paper not only describes details of a prototype monitoring system that uses information technology and sensors capable of providing more accurate knowledge of bridge performance than conventional ways but also shows a few specific examples of bridge condition assessment based on vehicle vibrations measured by using an in-service public bus equipped with vibration measurement instrumentation. This paper also describes a sensitivity analysis of deteriorating bridges based on simulation of the acceleration response of buses conducted by the "substructure method" employing a finite element model to verify the above bridge performance results. The main conclusions obtained in this study can be summarized as follows: (1) Because the vibration responses of passenger vehicles, such as buses, have a good linear relationship with the vibration responses of the target bridges, the proposed system can be used as a practical monitoring system for bridge condition assessment. (2) The results of sensitivity analysis performed by the substructure method show that bus vibration responses are useful for evaluating target bridge performance. (3) The proposed method was applied to a network of real bridges in a local area to evaluate its effectiveness. The results indicate that the proposed method can be used to prioritize the repair/strengthening works of existing bridges based on various vibration information in order to help bridge administrators establish rational maintenance strategies.

  3. Performance, Career Dynamics, and Span of Control

    DEFF Research Database (Denmark)

    Smeets, Valerie Anne Rolande; Waldman, Michael; Warzynski, Frederic Michel Patrick

    . In this paper we first extend the theoretical literature on the scale-of-operations effect to allow firms’ beliefs concerning a manager’s ability to evolve over the manager’s career, where much of our focus is the determinants of span of control. We then empirically investigate testable predictions from......There is an extensive theoretical literature based on what is called the scale-of-operations effect, i.e., the idea that the return to managerial ability is higher the more resources the manager influences with his or her decisions. This idea leads to various testable predictions including...... that higher ability managers should supervise more subordinates, or equivalently, have a larger span of control. And although some of this theory’s predictions have been empirically investigated, there has been little systematic investigation of the theory’s predictions concerning span of control...

  4. Spanning organizational boundaries to manage creative processes:

    DEFF Research Database (Denmark)

    Andersen, Poul Houman; Kragh, Hanne; Lettl, Christopher

    2013-01-01

    In order to continue to be innovative in the current fast-paced and competitive environment, organizations are increasingly dependent on creative inputs developed outside their boundaries. The paper addresses the boundary spanning activities that managers undertake to a) select and mobilize...... creative talent, b) create shared identity, and c) combine and integrate knowledge in innovation projects involving external actors. We study boundary spanning activities in two creative projects in the LEGO group. One involves identifying and integrating deep, specialized knowledge, the other focuses...... on the use of external actors as a source of broad, not necessarily fully developed ideas. We find that the boundary spanning activities in these two projects differ in respect, among other things, of how the firm selects participants, formulates problems, and aligns the expectations of internal and external...

  5. Vibration control of bridge subjected to multi-axle vehicle using multiple tuned mass friction dampers

    Science.gov (United States)

    Pisal, Alka Y.; Jangid, R. S.

    2016-06-01

    The effectiveness of tuned mass friction damper (TMFD) in reducing undesirable resonant response of the bridge subjected to multi-axle vehicular load is investigated. A Taiwan high-speed railway (THSR) bridge subjected to Japanese SKS (Salkesa) train load is considered. The bridge is idealized as a simply supported Euler-Bernoulli beam with uniform properties throughout the length of the bridge, and the train's vehicular load is modeled as a series of moving forces. Simplified model of vehicle, bridge and TMFD system has been considered to derive coupled differential equations of motion which is solved numerically using the Newmark's linear acceleration method. The critical train velocities at which the bridge undergoes resonant vibration are investigated. Response of the bridge is studied for three different arrangements of TMFD systems, namely, TMFD attached at mid-span of the bridge, multiple tuned mass friction dampers (MTMFD) system concentrated at mid-span of the bridge and MTMFD system with distributed TMFD units along the length of the bridge. The optimum parameters of each TMFD system are found out. It has been demonstrated that an optimized MTMFD system concentrated at mid-span of the bridge is more effective than an optimized TMFD at the same place with the same total mass and an optimized MTMFD system having TMFD units distributed along the length of the bridge. However, the distributed MTMFD system is more effective than an optimized TMFD system, provided that TMFD units of MTMFD system are distributed within certain limiting interval and the frequency of TMFD units is appropriately distributed.

  6. Weight-Constrained Minimum Spanning Tree Problem

    OpenAIRE

    Henn, Sebastian Tobias

    2007-01-01

    In an undirected graph G we associate costs and weights to each edge. The weight-constrained minimum spanning tree problem is to find a spanning tree of total edge weight at most a given value W and minimum total costs under this restriction. In this thesis a literature overview on this NP-hard problem, theoretical properties concerning the convex hull and the Lagrangian relaxation are given. We present also some in- and exclusion-test for this problem. We apply a ranking algorithm and the me...

  7. Seismic studies of the San Francisco-Oakland Bay Bridge

    Energy Technology Data Exchange (ETDEWEB)

    Astaneh-Asl, A; Larsen, S; McCallen, D

    1999-08-17

    Computational simulation plays a central role in the engineering analysis and design of major bridge structures and accurate simulations are essential for the development of earthquake resistant and economical structural designs. This paper describes new methodologies and computational tools which have recently been developed for simulating earthquake ground motions and the seismic response of cable supported bridges. The simulation tools are described and an example application for an important long-span suspension bridge is demonstrated. The application portion of the study has particular focus on the potential damaging effects of long period displacement pulses and permanent ground displacements which can occur when a bridge is located in the near-field of a major earthquake fault.

  8. Sustainable Bridge Infrastructure Procurement

    DEFF Research Database (Denmark)

    Safi, Mohammed; Du, Guangli; Simonsson, Peter

    2016-01-01

    The lack of a flexible but systematic approach for integrating lifecycle aspects into bridge investment decisions is a major obstacle hindering the procurement of sustainable bridge infrastructures. This paper addresses this obstacle by introducing a holistic approach that agencies could use...

  9. Principles of Bridge Reliability

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Nowak, Andrzej S.

    The paper gives a brief introduction to the basic principles of structural reliability theory and its application to bridge engineering. Fundamental concepts like failure probability and reliability index are introduced. Ultimate as well as serviceability limit states for bridges are formulated...

  10. Bridge the Gap

    DEFF Research Database (Denmark)

    Marselis, Randi Lorenz

    2017-01-01

    This article focuses on photo projects organised for teenage refugees by the Society for Humanistic Photography (Berlin, Germany). These projects, named Bridge the Gap I (2015), and Bridge the Gap II (2016), were carried out in Berlin and brought together teenagers with refugee and German...

  11. Vortex induced vibrations of free span pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Koushan, Kamran

    2009-07-01

    Pipelines from offshore petroleum fields must frequently pass over areas with uneven sea floor. In such cases the pipeline may have free spans when crossing depressions. Hence, if dynamic loads can occur, the free span may oscillate and time varying stresses may give unacceptable fatigue damage. A major source for dynamic stresses in free span pipelines is vortex induced vibrations (VIV) caused by steady current. This effect is in fact dominating on deep water pipelines since wave induced velocities and accelerations will decay with increasing water depth. The challenge for the industry is then to verify that such spans can sustain the influence from the environment throughout the lifetime of the pipeline. The aim of the present project is to improve the understanding of vortex induced vibrations (VIV) of free span pipelines, and thereby improve methods, existing computer programs and guidelines needed for design verification. This will result in more cost effective and reliable offshore pipelines when laid on a very rugged sea floor. VIV for multiple span pipeline is investigated and the dynamical interaction between adjacent spans has been shown. The interaction may lead to increased or decreased response of each spans depending on the current speed and the properties for the two spans. The extension of the contact zone between the spans and sea floor parameters will of course also be important for the interaction effect. The influence from temperature variation on vortex induced vibrations has been demonstrated. The response frequency is influenced through changes in pipe tension and sag. Both increase and decrease of the response frequency may be experienced. Moreover, it is shown that the influence from snaking of the pipe on the temperature effect is small, at least for large diameter pipes. A free span pipeline will necessarily oscillate close to the seabed. The presence of the seabed will therefore have some influences on the ambient flow profile and also

  12. Steel structure (bridge and building); Doboku/kenchiku bun`ya ni okeru yosetsu gijutsu no tenkai

    Energy Technology Data Exchange (ETDEWEB)

    Fukazawa, M. [Yokogawa Bridge Corp., Tokyo (Japan)

    1996-01-05

    In this article, the trends of welding engineering are discussed in two groups, namely bridges and steel frames. First of all, in the field of bridges, as the themes of technical innovation of steel bridges, the challenge to build long span bridges, coping with new structural forms, and rationalization of general bridges are selected. Concerning very long bridges, considerable elongation of its spans and technological development for materials, design, construction and erection relating to improvement of profitability become inevitable. Besides, in addition to the functions of bridges, the bridges playing the roles of environmental and/or artistic structures become many, thereby the cases of using welding for the site joints increase. As the measure for rationalize bridge construction, it is to reduce steel weight and working costs for increasing profitability, and the progress of welding technology therefor has been observed. With regard to the manufacture of bridge portions in a factory, labor saving, automatization and robotization of in-house welding have been made, and bridge maintenance as well as pursuance of attaining the state of maintenance free are also important. The trend that the bridge load is becoming larger and enhancement of earthquake resistance are also important. Regarding steel frames, functionalization of steel, making steel very thick, various automatization of manufacturing, and pursuance of earthquake resistant safety are being made. 14 refs., 7 figs.

  13. Variable Span Filters for Speech Enhancement

    DEFF Research Database (Denmark)

    Jensen, Jesper Rindom; Benesty, Jacob; Christensen, Mads Græsbøll

    2016-01-01

    optimal filters using a joint diagonalization as a basis. This gives excellent control over the performance, as we can optimize for noise reduction or signal distortion performance. Results from real data experiments show that the proposed variable span filters can achieve better performance than existing...

  14. SPAN - Terminal sterilization process analysis program

    Science.gov (United States)

    1969-01-01

    Computer program, SPAN, measures the dry heat thermal sterilization process applied to a planetary capsule and calculates the time required for heat application, steady state conditions, and cooling. The program is based on the logarithmic survival of micro-organisms. Temperature profiles must be input on tape.

  15. SPAN C - Terminal sterilization process analysis program

    Science.gov (United States)

    1969-01-01

    Computer program, SPAN-C, measures the dry heat thermal sterilization process applied to a planetary capsule and calculates the time required for heat application, steady state conditions, and cooling. The program is based on the logarithmic survival of micro-organisms. Temperature profiles must be input on cards.

  16. Friendship and adaption across the life span

    NARCIS (Netherlands)

    Hartup, W.W.; Stevens, N.L.

    1999-01-01

    Friends foster self-esteem and a sense of well-being, socialize one another, and support one another in coping with developmental transitions and life stress. Friends engage in different activities with one another across the life span, but friendship is conceived similarly by children and adults. F

  17. Boundary Spanning in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    of Indian IT vendor managers who are responsible for developing client relations and coordinating complex global development projects. The authors revise a framework of boundary spanning leadership practices to adapt it to an offshore outsourcing context. The empirical investigation highlights how...

  18. Visual Search Across the Life Span

    Science.gov (United States)

    Hommel, Bernhard; Li, Karen Z. H.; Li, Shu-Chen

    2004-01-01

    Gains and losses in visual search were studied across the life span in a representative sample of 298 individuals from 6 to 89 years of age. Participants searched for single-feature and conjunction targets of high or low eccentricity. Search was substantially slowed early and late in life, age gradients were more pronounced in conjunction than in…

  19. The application of structural health monitoring system technology using FBG to the No. 2 Wuhan bridge over the Yangtze river

    Science.gov (United States)

    Liu, Shengchun; Jiang, Desheng

    2008-12-01

    Bridge engineering offer many unique opportunities for the use of advanced optical fiber sensing technology. In this paper, the state-of-the-art of bridge structural health monitoring system(SHMS) based on optical fiber sensing technology are reviewed and some disadvantages in present SHMS based on optical fiber sensing technology for existing long-span bridge are indicated. In order to overcome those disadvantages, some fiber Bragg grating (FBG) products developed by authors and corresponding industrialization enterprise are introduced. Focusing on an existing long-span cable-stayed bridge-Wuhan Yangtze No.2 Bridge, the operational condition of the multi-parameter bridge SHMS mainly based on FBG sensors is presented. Some initial monitoring results show that the whole performance of the SHMS FBGbased is reliable and measuring data are reasonable.

  20. Seismic response of skewed RC box-girder bridges

    Institute of Scientific and Technical Information of China (English)

    Ahmed Abdel-Mohti; Gokhan Pekcan

    2008-01-01

    It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities.Since the 1971 San Fernando earthquake,there has been a better understanding of the seismic performance of bridges.Nonetheless,there are no detailed guidelines addressing the performance of skewed highway bridges.Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex.Therefore,there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges.This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees,analytically.Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000.Different types of analysis were considered on both models such as:nonlinear static pushover,and linear and nonlinear time history analyses.A comparison was conducted between FE and BS,different skew angles,abutment support conditions,and time history and pushover analysis.It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles.Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis.Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.

  1. Ambient Vibration Test on Reinforced Concrete Bridges

    Directory of Open Access Journals (Sweden)

    Idris Nurul Shazwin

    2016-01-01

    Full Text Available An investigation was carried out to determine dynamic characteristic of reinforced concrete (RC bridges by using ambient vibration test (AVT. The ambient vibration sources on bridges may come from traffic, wind, wave motion and seismic events. AVT describes the dynamic characteristics of the bridge and ground by measuring the natural frequencies using highly sensitive seismometer sensor. This test is beneficial due to light weight equipment and smaller number of operator required, cheap and easy to be handled. It is able to give a true picture of the bridge dynamic behavior without any artificial force excitation when vibration data is recorded. A three-span reinforced concrete bridge located in Sri Medan, Batu Pahat, Johor was measured by using microtremor equipment consist of three units of 1 Hz eigenfrequency passive sensors used in this test was performed in normal operating condition without excitation required from any active sources or short period noise perturbations. Ten measurements were conducted on the bridge deck and ten measurements on the ground surface in order to identify the natural frequencies of the bridge. Several peak frequencies were identified from three components of Fourier Amplitude Spectra (FAS in transverse (North-South, longitudinal (East-West and vertical (Up-Down direction as well as squared average Horizontal to Vertical Spectral Ratio (HVSR of ground response, computed by using Geopsy software. From the result, it was expected the bridge have five vibration modes frequencies in the range of 1.0 Hz and 7.0 Hz with the first two modes in the transverse and longitudinal direction having a frequency 1.0 Hz, the third mode is 2.2 Hz in transverse direction, fourth and fifth mode is 5.8 Hz and 7.0 Hz. For ground natural frequencies are in range 1.0 Hz to 1.3 Hz for North-South direction and 1.0 Hz to 1.6 Hz for East-West direction. Finally the results are compared with several empirical formulas for simple

  2. Shear distortion and failure of capillary bridges. Wetting information beyond contact angle analysis.

    Science.gov (United States)

    Wang, Liming; McCarthy, Thomas J

    2013-06-25

    Water capillary bridges are prepared that span hydrophilic pinning features on parallel opposing smooth, flat, and hydrophobic surfaces. These bridges are distorted by shearing the parallel plates at a low rate. The capillary bridges lengthen and distort to balance Laplace pressure (equilibrate mean curvature) as the features are separated and eventually rupture at a distance that is a function of the liquid volume, the advancing and receding contact angles of the surfaces, the separation between the parallel surfaces, and in particular, the shape and orientation of the hydrophilic pinning features. Two modes of capillary bridge failure are observed: (1) tensile, in which the capillary bridge breaks to form sessile drops on both the upper and lower surfaces, and (2) sessile, in which sessile capillary bridge rupture occurs on one surface to form a puddle (contact-line-distorted sessile drop) on the feature and a retained capillary bridge spanning the hydrophobic surface and the hydrophilic feature on the opposing surface. The shape and orientation of the features control the mode of capillary bridge failure as well as the distribution of water between the two separate sessile drops or the retained capillary bridge and the puddle.

  3. Torsional stiffness degradation and aerostatic divergence of suspension bridge decks

    Science.gov (United States)

    Zhang, Z. T.; Ge, Y. J.; Yang, Y. X.

    2013-07-01

    The mechanism of aerostatic torsional divergence (ATD) of long-span suspension bridges is investigated. A theoretical analysis on the basis of a generalized model is presented, showing that the vertical motion of a bridge deck is crucial to the torsional stiffness of the whole suspended system, and that the vertical motion of either cable with a magnitude beyond a certain threshold could result in a sudden degradation of the torsional stiffness of the system. This vertical motion-induced degradation of stiffness is recognized as the main reason for the ATD. Long-span suspension bridges are susceptible to such a type of divergence, especially when they are immersed in turbulent wind fields. The divergences that occur in turbulent wind fields differ significantly from those in smooth wind fields, and the difference is well explained by the generalized model that the loosening of any one cable could result in the vanishing of the part of stiffness provided by the whole cable system. The mechanism revealed in this paper leads to a definition of the critical wind speed of the ATD in a turbulent flow; that is, the one resulting in a vertical motion so large as to loosen either cable to a stressless state. Numerical results from the nonlinear finite-element (FE) analysis of the Xihoumen suspension bridge, in conjunction with observations from wind tunnel tests on an aero-elastic full bridge model, are in support of the viewpoint presented in this study.

  4. Study on the Spatial Stress of the Chongqing Yangtze River Bridge in China

    Directory of Open Access Journals (Sweden)

    Yan Li

    2014-09-01

    Full Text Available Continuous rigid-frame bridges are usually used in building bridges with long span and high piers. It is characterized by the consolidation between piers and beams in the middle of bridge piers and flexible bridge piers in the lower part. Among all the factors, curvature has the most obvious influence on the stress of curved continuous rigid-frame bridge, because of which, the curved beam bridge produces coupling effect of bending moment and receives complicated stress, leading to the deformation such as torsion and displacement of radial direction. No matter it is the castscaffold construction or cantilever construction, for continuous rigid-frame bridges, considering that after the long term creep of concrete, structure stress tends to be in a drop-frame state, so it is necessary to know the mechanical properties of the finished bridge. Taking the Chongqing Yangtze River Bridge as an example, this paper mainly analyzes the internal forces and deformations of a finished curved continuotus rigid-frame bridge by establishing a spatial finite element model with Midas Civil 2006 software and by changing the model’s radius of curvature. The results show that as the curvature increases, the vertical deformation and torsion angle of the long-span curved continuous rigid-frame bridge are both reduced under the effect of a dead load and prestressed load, presenting mechanical properties of bridge, namely, “coupling effect of bending moment”. In the model analyzed, the deformation of the bridge in the transverse direction also behaves a trend of gradual decrease with an increase in radius of curvature with the range 500–2000 m.

  5. Bridge technology report

    CERN Document Server

    2013-01-01

    Please note this is a Short Discount publication. As LANs have proliferated, new technologies and system concepts have come to the fore. One of the key issues is how to interconnect networks. One means of interconnection is to use a 'bridge'. Other competing technologies are repeaters, routers, and gateways. Bridges permit traffic isolation, connect network segments together and operate at the MAC layer. Further, because they operate at the MAC layer, they can handle a variety of protocols such as TCP/IP, SNA, and X.25. This report focuses on the specific technology of bridging two netw

  6. Minimum depth of soil cover above long-span soil-steel railway bridges

    National Research Council Canada - National Science Library

    Esmaeili, Morteza; Zakeri, Jabbar Ali; Abdulrazagh, Parisa Haji

    2013-01-01

    .... The currently developed formula for determining the minimum depth of covers by existing codes is typically based on vehicle loads and non-stiffened panels and takes into consideration the geometrical...

  7. Bridging the great divide: Contested Kosovo span is a symbol of international failure

    Directory of Open Access Journals (Sweden)

    Taylor Scott

    2008-01-01

    Full Text Available The paper offers a first-hand insight into the situation in Kosovo shortly after its unilateral declaration of independence in February 2008 and takes a look at the unexpectedly poor results of the UN interim administration of Kosovo. Arguing against recognition of Kosovo’s independence, it draws attention to the fact that in 2007 a number of UN observers took the unprecedented step of compiling an independent analysis, which they published and circulated without filtering it through the chain of command and that in the immediate aftermath of Kosovo’s declared independence, a large number of UN field officers voiced their concerns about the international community turning a blind eye to the reality of the situation on the ground.

  8. Reability based design optimization of long-span bridges uneder flutter constraint

    OpenAIRE

    Kusano, Ibuki

    2016-01-01

    [Resumen] Se ha aplicado optimización probabilista (RBDO) a puentes colgantes de gran vano considerando condiciones de flameo mediante tres métodos diferentes cuyas denominaciones anglosajonas son Reliability Index Approach, Performance Measure Approach y Sequential Optimization and Reliability Assessment. Se considera la existencia de incertidumbre en la velocidad extremal de viento en el emplazamiento del puente, y en las funciones de flameo obtenidas experimentalmente en ...

  9. The bridge helix coordinates movements of modules in RNA polymerase

    Directory of Open Access Journals (Sweden)

    Landick Robert

    2010-11-01

    Full Text Available Abstract The RNA polymerase 'bridge helix' is a metastable α-helix that spans the leading edge of the enzyme active-site cleft. A new study published in BMC Biology reveals surprising tolerance to helix-disrupting changes in a region previously thought crucial for translocation, and suggests roles for two hinge-like segments of the bridge helix in coordinating modules that move during the nucleotide-addition cycle. See Research article: http://www.biomedcentral.com/1741-7007/8/134

  10. Study of displacements of a bridge abutment using FEM

    Directory of Open Access Journals (Sweden)

    Wymysłowski Michał

    2016-06-01

    Full Text Available Steel sheet piles are often used to support excavations for bridge foundations. When they are left in place in the permanent works, they have the potential to increase foundation bearing capacity and reduce displacements; but their presence is not usually taken into account in foundation design. In this article, the results of finite element analysis of a typical abutment foundation, with and without cover of sheet piles, are presented to demonstrate these effects. The structure described is located over the Więceminka river in the town of Kołobrzeg, Poland. It is a single-span road bridge with reinforced concrete slab.

  11. Career development: a life span issue.

    Science.gov (United States)

    Sterns, H L; Dorsett, J G

    1994-01-01

    One of the challenges for individuals pursuing a career throughout their life span is how to maintain a high level of professional competence. As the composition of the workforce changes, and new technologies are developed, workers are faced with changing job demands and pressures. A major issue for the 1990s is how long a worker's skills will remain current. With rapid technological changes, workers may find it necessary to update continually their knowledge, skills, and abilities or risk becoming obsolete. Factors such as individuals' motivation and attitudes and organizational climate can contribute to choices regarding career development. Current research on the factors that contribute to career development activities is reviewed, along with the impact of multiple career transitions throughout the life span. Interventions such as retraining and outplacement, which allow individuals in later life to continue work, change jobs, and further develop their careers, are also discussed.

  12. Span morphing using the GNATSpar wing

    OpenAIRE

    2016-01-01

    Rigid wings usually fly at sub-optimal conditions generating unnecessary aerodynamic loses represented in flight time, fuel consumption, and unfavourable operational characteristics. High aspect ratio wings have good range and fuel efficiency, but lack manoeuvrability. On the other hand, low aspect ratio wings fly faster and are more manoeuvrable, but have poor aerodynamic performance. Span morphing technology allows integrating both features in a single wing design and allows continuously ad...

  13. A Lattice Spanning-Tree Entropy Function

    OpenAIRE

    Glasser, ML; Lamb, George

    2005-01-01

    The function $$W(aq,b)=\\int\\int_0^{2\\pi}\\ln[1-a\\cos x-b\\cos y-(1-a-b)\\cos(x+y)]dxdy$$ which expresses the spanning-tree entropy for various two dimensional lattices, for example, is evaluated directly in terms of standard functions. It is applied to derive several limiting values of the triangular lattice Green function.

  14. Vision in Flies: Measuring the Attention Span.

    Science.gov (United States)

    Koenig, Sebastian; Wolf, Reinhard; Heisenberg, Martin

    2016-01-01

    A visual stimulus at a particular location of the visual field may elicit a behavior while at the same time equally salient stimuli in other parts do not. This property of visual systems is known as selective visual attention (SVA). The animal is said to have a focus of attention (FoA) which it has shifted to a particular location. Visual attention normally involves an attention span at the location to which the FoA has been shifted. Here the attention span is measured in Drosophila. The fly is tethered and hence has its eyes fixed in space. It can shift its FoA internally. This shift is revealed using two simultaneous test stimuli with characteristic responses at their particular locations. In tethered flight a wild type fly keeps its FoA at a certain location for up to 4s. Flies with a mutation in the radish gene, that has been suggested to be involved in attention-like mechanisms, display a reduced attention span of only 1s.

  15. Vision in Flies: Measuring the Attention Span.

    Directory of Open Access Journals (Sweden)

    Sebastian Koenig

    Full Text Available A visual stimulus at a particular location of the visual field may elicit a behavior while at the same time equally salient stimuli in other parts do not. This property of visual systems is known as selective visual attention (SVA. The animal is said to have a focus of attention (FoA which it has shifted to a particular location. Visual attention normally involves an attention span at the location to which the FoA has been shifted. Here the attention span is measured in Drosophila. The fly is tethered and hence has its eyes fixed in space. It can shift its FoA internally. This shift is revealed using two simultaneous test stimuli with characteristic responses at their particular locations. In tethered flight a wild type fly keeps its FoA at a certain location for up to 4s. Flies with a mutation in the radish gene, that has been suggested to be involved in attention-like mechanisms, display a reduced attention span of only 1s.

  16. Bridging Humanism and Behaviorism.

    Science.gov (United States)

    Chu, Lily

    1980-01-01

    Humanistic behaviorism may provide the necessary bridge between behaviorism and humanism. Perhaps the most humanistic approach to teaching is to learn how certain changes will help students and how these changes can be accomplished. (Author/MLF)

  17. State's First Bridge

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Article with details on the state's first bridge that crossed the Noxubee River adjacent to the Noxubee National Wildlife Refuge Boundary. Details also included...

  18. Bridged Race Population Estimates

    Data.gov (United States)

    U.S. Department of Health & Human Services — Population estimates from "bridging" the 31 race categories used in Census 2000, as specified in the 1997 Office of Management and Budget (OMB) race and ethnicity...

  19. Research on tensile strength characteristics of bridge deck pavement bonding layers

    Science.gov (United States)

    Wu, Shaopeng; Han, Jun

    2010-03-01

    As the development of the traffic in the world, the bridge deck pavement is playing a more and more important role in the whole traffic system. Big span bridge has become more and more especially cement concrete bridge, therefore the bridge deck pavement bonding layers are emphasized as an important part of bridge traffic system, which can mitigate travel impact to bridge and magnify stationary or traffic amenity. The quality and durability of deck pavement bonding layer has directly effect on traffic safety, comfort, durability and investment of bridge. It represents the first line of defence against the ingress of water, road de-icing salts and aggressive chemicals. In real project, many early age damage of bridge deck pavement has become serious disease that affecting the function of bridge. During the construction of the bridge deck, many types of asphalt binders were used, such as styrene-butadiene-styrene (SBS) modified asphalt, styrene-butadiene rubber (SBR) modified asphalt, neoprene latex asphalt, etc. In this paper UTM-25 was used to test the tensile strength of different bridge deck pavement bonding layers with the different treatment methods to inter-surface.

  20. Germ Cell Intercellular Bridges

    Science.gov (United States)

    Greenbaum, Michael P.; Iwamori, Tokuko; Buchold, Gregory M.; Matzuk, Martin M.

    2011-01-01

    Stable intercellular bridges are a conserved feature of gametogenesis in multicellular animals observed more than 100 years ago, but their function was unknown. Many of the components necessary for this structure have been identified through the study of cytokinesis in Drosophila; however, mammalian intercellular bridges have distinct properties from those of insects. Mammalian germ cell intercellular bridges are composed of general cytokinesis components with additional germ cell–specific factors including TEX14. TEX14 is an inactive kinase essential for the maintenance of stable intercellular bridges in gametes of both sexes but whose loss specifically impairs male meiosis. TEX14 acts to impede the terminal steps of abscission by competing for essential component CEP55, blocking its interaction in nongerm cells with ALIX and TSG101. Additionally, TEX14-interacting protein RBM44, whose localization in stabile intercellular bridges is limited to pachytene and secondary spermatocytes, may participate in processes such as RNA transport but is nonessential to the maintenance of intercellular bridge stability. PMID:21669984

  1. Study on longitudinal wind load calculation method of cables for cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    Pei Minshan; Zhang Xigang; Zhu Bin; Hou Bin; Liu Changpeng

    2009-01-01

    Along with the expanding of span of cable-stayed bridge, wind load becomes a more and more important controlling factor for bridge the design. A very large proportion of the wind load acting on cables has exceeded that acting on deck. There was not any detailed prescript in Chinese code for calculation of longitudinal wind load on cables due to lack of theoretical research and experiment, and conservative simplified calculation was adopted during design, which leads to conservative and uneconomical design of structures. To resolve this problem, cable force experiment was carried out during the design of Sutong Bridge. By comparing with international research results, the calculation formula of longitudinal wind drag coefficient for cables was advanced to fill the blank of bridge wind resistant code of China, and has already been adopted in the Highway Bridge Wind Resistant Design Code (JTG/T D60-01-2004) with great significance for bridge engineering.

  2. Research on the stiffening girder erection sequence of three-tower suspension bridge

    Institute of Scientific and Technical Information of China (English)

    Zheng Runqing; Luo Xiheng

    2012-01-01

    Compared to the conventional two-tower suspension bridge, the three-tower suspension bridge has obviously different characteristics in structural performance because of the extra middle tower and main span. The construction sequence for the stiffening girder is significantly different between the three-tower suspension bridge and the two-tower suspension bridge. The tangential angle of the main cable is one of the controlling factors of the stiffening girder erection stage for a suspension bridge. According to 5 feasible cases for the stiffening girder erection scheme in Taizhou Bridge, the research about the tangential angle in each case mentioned above was made, and some factors that should be taken into account for the erection scheme of stiffening girder were pointed out.

  3. Optimal randomized EREW PRAM algorithms for finding spanning forests and for other basic graph connectivity problems

    Energy Technology Data Exchange (ETDEWEB)

    Halperin, S.; Zwick, U. [Tel Aviv Univ. (Israel)

    1996-12-31

    We present the first randomized O(log n) time and O(m + n) work EREW PRAM algorithm for finding a spanning forest of an undirected graph G = (V, E) with n vertices and m edges. Our algorithm is optimal with respect to time, work and space. As a consequence we get optimal randomized EREW PRAM algorithms for other basic connectivity problems such as finding a bipartite partition, finding bridges and biconnected components, and finding Euler tours in Eulerean graphs. For other problems such as finding an ear decomposition, finding an open ear decomposition, finding a strong orientation, and finding an st-numbering we get optimal randomized CREW PRAM algorithms.

  4. Distributed strain monitoring for bridges: temperature effects

    Science.gov (United States)

    Regier, Ryan; Hoult, Neil A.

    2014-03-01

    To better manage infrastructure assets as they reach the end of their service lives, quantitative data is required to better assess structural behavior and allow for more informed decision making. Distributed fiber optic strain sensors are one sensing technology that could provide comprehensive data for use in structural assessments as these systems potentially allow for strain to be measured with the same accuracy and gage lengths as conventional strain sensors. However, as with many sensor technologies, temperature can play an important role in terms of both the structure's and sensor's performance. To investigate this issue a fiber optic distributed strain sensor system was installed on a section of a two span reinforced concrete bridge on the TransCanada Highway. Strain data was acquired several times a day as well as over the course of several months to explore the effects of changing temperature on the data. The results show that the strain measurements are affected by the bridge behavior as a whole. The strain measurements due to temperature are compared to strain measurements that were taken during a load test on the bridge. The results show that even a small change in temperature can produce crack width and strain changes similar to those due to a fully loaded transport truck. Future directions for research in this area are outlined.

  5. Flow field analysis of a pentagonal-shaped bridge deck by unsteady RANS

    Directory of Open Access Journals (Sweden)

    Md. Naimul Haque

    2016-01-01

    Full Text Available Long-span cable-stayed bridges are susceptible to dynamic wind effects due to their inherent flexibility. The fluid flow around the bridge deck should be well understood for the efficient design of an aerodynamically stable long-span bridge system. In this work, the aerodynamic features of a pentagonal-shaped bridge deck are explored numerically. The analytical results are compared with past experimental work to assess the capability of two-dimensional unsteady RANS simulation for predicting the aerodynamic features of this type of deck. The influence of the bottom plate slope on aerodynamic response and flow features was investigated. By varying the Reynolds number (2 × 104 to 20 × 104 the aerodynamic behavior at high wind speeds is clarified.

  6. Research on Collapse Process of Cable-Stayed Bridges under Strong Seismic Excitations

    Directory of Open Access Journals (Sweden)

    Xuewei Wang

    2017-01-01

    Full Text Available In order to present the collapse process and failure mechanism of long-span cable-stayed bridges under strong seismic excitations, a rail-cum-road steel truss cable-stayed bridge was selected as engineering background, the collapse failure numerical model of the cable-stayed bridge was established based on the explicit dynamic finite element method (FEM, and the whole collapse process of the cable-stayed bridge was analyzed and studied with three different seismic waves acted in the horizontal longitudinal direction, respectively. It can be found from the numerical simulation analysis that the whole collapse failure process and failure modes of the cable-stayed bridge under three different seismic waves are similar. Furthermore, the piers and the main pylons are critical components contributing to the collapse of the cable-stayed bridge structure. However, the cables and the main girder are damaged owing to the failure of piers and main pylons during the whole structure collapse process, so the failure of cable and main girder components is not the main reason for the collapse of cable-stayed bridge. The analysis results can provide theoretical basis for collapse resistance design and the determination of critical damage components of long-span highway and railway cable-stayed bridges in the research of seismic vulnerability analysis.

  7. Evaluation of Dynamic Load Factors for a High-Speed Railway Truss Arch Bridge

    Directory of Open Access Journals (Sweden)

    Ding Youliang

    2016-01-01

    Full Text Available Studies on dynamic impact of high-speed trains on long-span bridges are important for the design and evaluation of high-speed railway bridges. The use of the dynamic load factor (DLF to account for the impact effect has been widely accepted in bridge engineering. Although the field monitoring studies are the most dependable way to study the actual DLF of the bridge, according to previous studies there are few field monitoring data on high-speed railway truss arch bridges. This paper presents an evaluation of DLF based on field monitoring and finite element simulation of Nanjing DaShengGuan Bridge, which is a high-speed railway truss arch bridge with the longest span throughout the world. The DLFs in different members of steel truss arch are measured using monitoring data and simulated using finite element model, respectively. The effects of lane position, number of train carriages, and speed of trains on DLF are further investigated. By using the accumulative probability function of the Generalized Extreme Value Distribution, the probability distribution model of DLF is proposed, based on which the standard value of DLF within 50-year return period is evaluated and compared with different bridge design codes.

  8. Decentralized Pricing in Minimum Cost Spanning Trees

    DEFF Research Database (Denmark)

    Hougaard, Jens Leth; Moulin, Hervé; Østerdal, Lars Peter

    In the minimum cost spanning tree model we consider decentralized pricing rules, i.e. rules that cover at least the ecient cost while the price charged to each user only depends upon his own connection costs. We de ne a canonical pricing rule and provide two axiomatic characterizations. First......, the canonical pricing rule is the smallest among those that improve upon the Stand Alone bound, and are either superadditive or piece-wise linear in connection costs. Our second, direct characterization relies on two simple properties highlighting the special role of the source cost....

  9. Procurement of Beams in Multiple D&B Bridge Projects

    Directory of Open Access Journals (Sweden)

    CT. Ramanathan

    2010-06-01

    Full Text Available Selected infrastructure development projects are being implemented by Design and Build (D&B pocurement system in Sabah (East Malaysia by the Public Works Department (PWD. In the first phase 45 bridge replacement projects were awarded in 5 packages. These simultaneous multiple Bridge projects are for the development of the backward areas and hence their timely completion is utmost important. Procurement and production of bridge beams have been the critical element of construction in these rural areas and no researches has been reported on various aspects of procurement of the bridge beams in multiple D&B projects. The aspects of procurement researched in this work include the determination of a common beam element for the ease of procurement and the optimization of the construction methodology, the finalization and purchasing plate dimensions to suite the manufacturer's production range, the delivery of materials, the planning and monitoring of fabrication, the preparation and assembly, and the erection and launching of beams. The beams are optimized using element optimization techniques. The most important problems in fabricating steel girders were in planning and scheduling of materials for the fabrication and the fabrication process. Findings in all the aspects of production of steel girders are highlighted through a case study of six long span bridges at various locations in Sabah. Solutions drawn from lessons learnt which minimize wastages, and aids in timely completion of beams in multiple bridge construction are discussed.

  10. Bridge aerodynamics and aeroelasticity: A comparison of modeling schemes

    Science.gov (United States)

    Wu, Teng; Kareem, Ahsan

    2013-11-01

    Accurate modeling of wind-induced loads on bridge decks is critical to ensure the functionality and survivability of long-span bridges. Over the last few decades, several schemes have emerged to model bridge behavior under winds from an aerodynamic/aeroelastic perspective. A majority of these schemes rely on the quasi-steady (QS) theory. This paper systematically compares and assesses the efficacy of five analytical models available in the literature with a new model presented herein. These models include: QS theory-based model, corrected QS theory-based model, linearized QS theory-based model, semi-empirical linear model, hybrid model, and the proposed modified hybrid model. The ability of these models to capture fluid memory and nonlinear effects either individually or collectively is examined. In addition, their ability to include the effects of turbulence in the approach flow on the bridge behavior is assessed. All models are compared in a consistent manner by utilizing the time domain approach. The underlying role of each model in capturing the physics of bridge behavior under winds is highlighted and the influence of incoming turbulence and its interaction with the bridge deck is examined. A discussion is included that focuses on a number of critical parameters pivotal to the effectiveness of corresponding models.

  11. Study on vulnerability assessment of cable-stayed bridges

    Science.gov (United States)

    Chang, C. C.; Yan, D.

    2006-03-01

    A structure is vulnerable if any small damage will trigger disproportionately large consequences, even leads to a cascade of failure events and progressive collapse. The structural vulnerability performance depends upon the properties, locations of damaged components and the way they are connected to the rest of the structure. In this paper, progressive failure analysis method is utilized for the vulnerability study of cable-stayed bridges. The goal of it is to identify various failure scenarios initiated from the sudden damage of some bridge components. Based on the analysis results, assuming that the behaviors of damaged components can be modeled using plastic hinges, the hybrid element model is introduced to derived the modified stiffness matrix considering both of the effects of bending moments and shear forces. Furthermore, the vulnerability index in terms of the nodal stiffness degradation can be analytically quantified, which could be regarded as an index to determine the bridge failure consequences, so that the vulnerability distribution graph for the whole bridge can be sketched to evaluate the bridge performances from vulnerability viewpoints. This quantitative approach is applicable for structural evaluation under unforeseen attack and illustrated on a typical long-span cable-stayed bridge.

  12. Doubling the width of the platform of the San Pedro bridge in Spain

    OpenAIRE

    Torroja, José A.; Simón-Talero, José M.; Hernández, Alejandro

    2011-01-01

    The San Pedro Bridge has six spans and is 750 m (2460 ft) long, 88 m (290 ft) high, 12 m (39 ft) wide, and curved with a radius of 700 m (2300 ft). It was built in 1993 using the cantilever method. Its super - structure is a prestressed concrete box girder with main spans of 150 m (490 ft). In 2008 and 2009, the width of the platform was enlarged to 23 m (75 ft) using five movable sets of scaffolding. The bridge remained open to traffic during construction. The original platform was widened 6...

  13. Geometric Nonlinear Analysis of Self-Anchored Cable-Stayed Suspension Bridges

    Directory of Open Access Journals (Sweden)

    Wang Hui-Li

    2013-01-01

    Full Text Available Geometric nonlinearity of self-anchored cable-stayed suspension bridges is studied in this paper. The repercussion of shrinkage and creep of concrete, rise-to-span ratio, and girder camber on the system is discussed. A self-anchored cable-stayed suspension bridge with a main span of 800 m is analyzed with linear theory, second-order theory, and nonlinear theory, respectively. In the condition of various rise-to-span ratios and girder cambers, the moments and displacements of both the girder and the pylon under live load are acquired. Based on the results it is derived that the second-order theory can be adopted to analyze a self-anchored cable-stayed suspension bridge with a main span of 800 m, and the error is less than 6%. The shrinkage and creep of concrete impose a conspicuous impact on the structure. And it outmatches suspension bridges for system stiffness. As the rise-to-span ratio increases, the axial forces of the main cable and the girder decline. The system stiffness rises with the girder camber being employed.

  14. Spanning Forests on Random Planar Lattices

    CERN Document Server

    Caracciolo, Sergio

    2009-01-01

    The generating function for spanning forests on a lattice is related to the q-state Potts model in a certain q -> 0 limit, and extends the analogous notion for spanning trees, or dense self-avoiding branched polymers. Recent works have found a combinatorial perturbative equivalence also with the (quadratic action) O(n) model in the limit n -> -1, the expansion parameter t counting the number of components in the forest. We give a random-matrix formulation of this model on the ensemble of degree-k random planar lattices. For k = 3, a correspondence is found with the Kostov solution of the loop-gas problem, which arise as a reformulation of the (logarithmic action) O(n) model, at n = -2. Then, we show how to perform an expansion around the t = 0 theory. In the thermodynamic limit, at any order in t we have a finite sum of finite-dimensional Cauchy integrals. The leading contribution comes from a peculiar class of terms, for which a resummation can be performed exactly.

  15. The Problem of Predecessors on Spanning Trees

    Directory of Open Access Journals (Sweden)

    V. S. Poghosyan

    2011-01-01

    Full Text Available We consider the equiprobable distribution of spanning trees on the square lattice. All bonds of each tree can be oriented uniquely with respect to an arbitrary chosen site called the root. The problem of predecessors is to find the probability that a path along the oriented bonds passes sequentially fixed sites i and j. The conformal field theory for the Potts model predicts the fractal dimension of the path to be 5/4. Using this result, we show that the probability in the predecessors problem for two sites separated by large distance r decreases as P(r ∼ r −3/4. If sites i and j are nearest neighbors on the square lattice, the probability P(1 = 5/16 can be found from the analytical theory developed for the sandpile model. The known equivalence between the loop erased random walk (LERW and the directed path on the spanning tree states that P(1 is the probability for the LERW started at i to reach the neighboring site j. By analogy with the self-avoiding walk, P(1 can be called the return probability. Extensive Monte-Carlo simulations confirm the theoretical predictions.

  16. Experimental study on the width of the turbulent area around bridge pier

    Institute of Scientific and Technical Information of China (English)

    ZHUANG Yuan; LIU Zu-yuan

    2007-01-01

    At present, the method of calculating the turbulent flow width around the bridge pier is not given in the "Standard for Inland River Navigation" (GB50139-2004) in China, and the bridge designer usually increases the bridge span in order to ensure the navigation safety, which increases both of the structural design difficulty and the project investments. Therefore, it is extremely essential to give a research on the turbulent flow width around the bridge pier. Through the experiments of the fixed bed and the mobile bed, the factors influencing the turbulent flow width around the bridge pier have been analyzed, such as the approaching flow speed, the water depth, the angles between the bridge pier and the flow direction, the sizes of bridge pier, the shapes of the bridge pier, and the scouring around the bridge pier, etc. Through applying the dimension analytic method to the measured data, the formula of calculating the turbulent flow width around the bridge pier is then inferred.

  17. Earthquake Performance Analysis of Steel Truss-Concrete Continuous Rigid Frame Bridge

    Directory of Open Access Journals (Sweden)

    Li Yuanming

    2014-04-01

    Full Text Available The steel truss-concrete Combination continuous rigid frame bridge is that we use steel truss for Principal stress structure.The seismic performance of a steel truss-concrete Combination continuous rigid frame bridge was studied in this paper. A dynamic spatial finite element model of Qingqiyong Bridge, which is a long span bridge, was created using MIDAS. Its natural frequency and vibration mode can be calculated,the seismic performance and structure stiffness were discussed and analyzed on the basis of calculated results. Design response spectrum and time-history method are used to calculate this bridge, seismic performance is discussed in this paper . Results show that natural frequency of the bridge is small, its period is long, and this kind of bridge is a new kind of earthquake resistant and energy-saving structure. Seismic effect has some effect on the bridge, especially the bending moment Along the bridge. The results of this paper can also provide some references for the design, construction, health monitoring and maintenance of bridges of like.

  18. Studies on Technical Development of Railway Steel-Concrete Composite Cirider Bridges in China

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    Steel-concrete composite girder bridge boasts the advantages of strong rigidity,low noise and low construction height.Along with the large-scale construction of passengerdedicated lines (PDL) and high-speed lines (HSL),tests and researches on steel-concrete composite girder bridges have been conducted with the main types of which including steel plate girder-concrete composite girder bridge,deck steel truss girder-concrete composite girder bridge,through steel truss girder-concrete composite girder bridge and through type tied arch composite girder bridge.Based on the application and researches on steel-concrete composite technology and in combination with the engineering construction of railway bridges,the construction of HSL and PDL and upgrading of existing lines for speed-up in China,this paper analyzes the main structural forms of through steel truss girder-concrete composite girder bridges with different spans and structure systems,carries out studies on the force acted upon these bridges and the related theory and methods for design and computation,and puts forward the solutions required in relation to the key technologies for further development of railway steel-concrete composite girder bridges.

  19. Evaluation Behavior of Qing Shan Concrete Bridge under Static Load Test

    Directory of Open Access Journals (Sweden)

    Haleem K. Hussain

    2011-07-01

    Full Text Available This study describes and evaluates the state of Qing Shang Bridge. The deterioration of bridge can be summarized due to increased internal forces may be a result of higher loading or due to the sever climatic and environmental weathers changes, bridges need reinforcement because damage due to external factors which reduced the cross-sectional resistance to external loads. The assessment of traffic loading on bridges is subject to large levels of uncertainty. While some allowance is provided in design codes for variable traffic conditions, they are conservative to allow for generalization at a safe level. Also this article identify the design demands of Qing Shan bridge which is located in China/ Heilongjiang Province, He gang - Nen Jiang Road 303 provincial highway, Wu Da Lian Chi area, is an important bridge in the urban areas. The investigation program was include the observation and evaluate the damage in T-section concrete beams , box girder bridges section in additional evaluate the whole state of bridges under static load test, the use of Finite Element Analysis was preferred method to study the behavior of concrete. Furthermore the load test program includes the main beams of bridge. The test results show that the bridge in general structural condition is good. T beam girder of the span No. 10 was tested for static load and need to be strengthening. The concrete box girder shows good state of condition, and no seriously damage effects.

  20. The aesthetic composite bridge.

    Science.gov (United States)

    Feinman, R A

    1997-01-01

    New developments are constantly introduced in the search for the optimal treatment modality to restore a single anterior tooth. The patient attention has shifted to aesthetics of the restoration, biocompatibility of the dental materials utilized, conservative preparation of the teeth to be restored, and the retention of intact adjacent dentition. The learning objective of this article is to review the methods currently utilized and to present a recently introduced treatment modality--the two-component bridge, which combines the strength and resiliency of composite resin with the aesthetic advantages of porcelain. The technology of the material is reviewed, the predominantly lingual tooth preparation procedures are outlined, and the bridge try-in is described. The advantages of the two-component bridge are presented along with the contraindications and suggestions of careful case selection. Three cases with congenitally missing maxillary lateral incisors in youthful patients are presented to supplement the theoretical outline and to describe and illustrate the clinical procedure.

  1. Istanbul Bridge Conference 2014

    CERN Document Server

    Gülkan, Polat; Mahmoud, Khaled

    2016-01-01

      The book includes peer-reviewed contributions selected from presentations given at the Istanbul Bridge Conference 2014, held from August 11 – 13 in Istanbul, Turkey. It reports on the current challenges in bridge engineering faced by professionals around the globe, giving a special emphasis to recently developed techniques, innovations and opportunities. The book covers key topics in the field, including modeling and analysis methods; construction and erection techniques; design for extreme events and condition assessment and structural health monitoring. There is a balanced presentation of theory, research and practice. This book, which provides the readers with a comprehensive and timely reference guide on current practices in bridge engineering, is intended for professionals, academic researchers and students alike.

  2. Active Control of Suspension Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper some recent research on active control of very long suspension bridges, is presented. The presentation is based on research work at Aalborg University, Denmark. The active control system is based on movable flaps attached to the bridge girder. Wind load on bridges with or without...... flaps attached to the girder is briefly presented. A simple active control system is discussed. Results from wind tunnel experiments with a bridge section show that flaps can be used effectively to control bridge girder vibrations. Flutter conditions for suspension bridges with and without flaps...

  3. Digital simulation of 3D turbulence wind field of Sutong Bridge based on measured wind spectra

    Institute of Scientific and Technical Information of China (English)

    Hao WANG; Zhou-hong ZONG; Ai-qun LI; Teng TONG; Jie NIU; Wen-ping DENG

    2012-01-01

    Time domain analysis is an essential implement to study the buffeting behavior of long-span bridges for it can consider the non-linear effect which is significant in long-span bridges.The prerequisite of time domain analysis is the accurate description of 3D turbulence winds.In this paper,some hypotheses for simplifying the 3D turbulence simulation of long-span cable-stayed bridges are conducted,considering the structural characteristics.The turbulence wind which is a 3D multivariate stochastic vector process is converted into four independent ID univariate stochastic processes.Based on recorded wind data from structural health monitoring system (SHMS) of the Sutong Bridge,China,the measured spectra expressions are then presented using the nonlinear least-squares fitting method.Turbulence winds at the Sutong Bridge site are simulated based on the spectral representation method and the Fast Fourier transform (FFT) technique,and the relevant results derived from target spectra including measured spectra and recommended spectra are compared.The reliability and accuracy of the presented turbulence simulation method are validated through comparisons between simulated and target spectra (measured and recommended spectra).The obtained turbulence simulations can not only serve further analysis of the buffeting behavior of the Sutong Bridge,but references for structural anti-wind design in adjacent regions.

  4. Static Testing of a Bridge Using an Interferometric Radar: The Case Study of “Ponte degli Alpini,” Belluno, Italy

    Directory of Open Access Journals (Sweden)

    Devis Dei

    2013-01-01

    Full Text Available Ground-based radar interferometry is an increasingly popular technique for monitoring civil infrastructures. In this paper, the static testing of a bridge is reported. It was an 8-span bridge, 297 m long, named “Ponte degli Alpini,” crossing the valley of the Ardo River. The radar has been used for testing a lateral span and a central span. The obtained results present elements of novelty not previously reported in the literature. In fact, some displacement measurements of the lateral span have been affected by a horizontal shift that has to be taken into account for a correct interpretation of the measured data. Furthermore, the measurements of the central span have been carried out with the radar positioned transversally with respect to the bridge deck; this unusual arrangement has allowed for obtaining displacement maps less geometrically distorted with respect to other cases reported in the literature.

  5. Bridge condition assessment based on long-term strain monitoring

    Science.gov (United States)

    Sun, LiMin; Sun, Shouwang

    2011-04-01

    In consideration of the important role that bridges play as transportation infrastructures, their safety, durability and serviceability have always been deeply concerned. Structural Health Monitoring Systems (SHMS) have been installed to many long-span bridges to provide bridge engineers with the information needed in making rational decisions for maintenance. However, SHMS also confronted bridge engineers with the challenge of efficient use of monitoring data. Thus, methodologies which are robust to random disturbance and sensitive to damage become a subject on which many researches in structural condition assessment concentrate. In this study, an innovative probabilistic approach for condition assessment of bridge structures was proposed on the basis of long-term strain monitoring on steel girder of a cable-stayed bridge. First, the methodology of damage detection in the vicinity of monitoring point using strain-based indices was investigated. Then, the composition of strain response of bridge under operational loads was analyzed. Thirdly, the influence of temperature and wind on strains was eliminated and thus strain fluctuation under vehicle loads is obtained. Finally, damage evolution assessment was carried out based on the statistical characteristics of rain-flow cycles derived from the strain fluctuation under vehicle loads. The research conducted indicates that the methodology proposed is qualified for structural condition assessment so far as the following respects are concerned: (a) capability of revealing structural deterioration; (b) immunity to the influence of environmental variation; (c) adaptability to the random characteristic exhibited by long-term monitoring data. Further examination of the applicability of the proposed methodology in aging bridge may provide a more convincing validation.

  6. Increasing the weight of minimum spanning trees

    Energy Technology Data Exchange (ETDEWEB)

    Frederickson, G.N.; Solis-Oba, R. [Purdue Univ., West Lafayette, IN (United States)

    1996-12-31

    Given an undirected connected graph G and a cost function for increasing edge weights, the problem of determining the maximum increase in the weight of the minimum spanning trees of G subject to a budget constraint is investigated. Two versions of the problem are considered. In the first, each edge has a cost function that is linear in the weight increase. An algorithm is presented that solves this problem in strongly polynomial time. In the second version, the edge weights are fixed but an edge can be removed from G at a unit cost. This version is shown to be NP-hard. An {Omega}(1/ log k)-approximation algorithm is presented for it, where k is the number of edges to be removed.

  7. Interorganizational Boundary Spanning in Global Software Development

    DEFF Research Database (Denmark)

    Søderberg, Anne-Marie; Romani, Laurence

    Western companies´ outsourcing of projects to emergent markets are increasingly being replaced by strategic partnerships that require closer collaboration between client and vendor. Existing research on global teamwork has primarily focused on the challenges, limitations and difficulties related...... to virtuality and cultural diversity. This paper, which draws on a case study of collaborative work in a global software development project, focuses on key boundary spanners in an Indian vendor company, who are responsible for developing trustful and sustainable client relations and coordinating complex...... projects across multiple cultures, languages, organisational boundaries, time zones and geographical distances. It looks into how these vendor managers get prepared for their complex boundary spanning work, which cross-cultural challenges they experience in their collaboration with Western clients...

  8. Galactic Archaeology and Minimum Spanning Trees

    CERN Document Server

    Macfarlane, B A; Flynn, C M L

    2015-01-01

    Chemical tagging of stellar debris from disrupted open clusters and associations underpins the science cases for next-generation multi-object spectroscopic surveys. As part of the Galactic Archaeology project TraCD (Tracking Cluster Debris), a preliminary attempt at reconstructing the birth clouds of now phase-mixed thin disk debris is undertaken using a parametric minimum spanning tree (MST) approach. Empirically-motivated chemical abundance pattern uncertainties (for a 10-dimensional chemistry-space) are applied to NBODY6-realised stellar associations dissolved into a background sea of field stars, all evolving in a Milky Way potential. We demonstrate that significant population reconstruction degeneracies appear when the abundance uncertainties approach 0.1 dex and the parameterised MST approach is employed; more sophisticated methodologies will be required to ameliorate these degeneracies.

  9. Faster generation of random spanning trees

    CERN Document Server

    Kelner, Jonathan A

    2009-01-01

    In this paper, we set forth a new algorithm for generating approximately uniformly random spanning trees in undirected graphs. We show how to sample from a distribution that is within a multiplicative $(1+\\delta)$ of uniform in expected time $\\TO(m\\sqrt{n}\\log 1/\\delta)$. This improves the sparse graph case of the best previously known worst-case bound of $O(\\min \\{mn, n^{2.376}\\})$, which has stood for twenty years. To achieve this goal, we exploit the connection between random walks on graphs and electrical networks, and we use this to introduce a new approach to the problem that integrates discrete random walk-based techniques with continuous linear algebraic methods. We believe that our use of electrical networks and sparse linear system solvers in conjunction with random walks and combinatorial partitioning techniques is a useful paradigm that will find further applications in algorithmic graph theory.

  10. NSI directed to continue SPAN's functions

    Science.gov (United States)

    Rounds, Fred

    1991-01-01

    During a series of network management retreats in June and July 1990, representatives from NASA Headquarters Codes O and S agreed on networking roles and responsibilities for their respective organizations. The representatives decided that NASA Science Internet (NSI) will assume management of both the Space Physics Analysis Network (SPAN) and the NASA Science Network (NSN). SPAN is now known as the NSI/DECnet, and NSN is now known as the NSI/IP. Some management functions will be distributed between Ames Research Center (ARC) and Goddard Space Flight Center (GSFC). NSI at ARC has the lead role for requirements generation and networking engineering. Advanced Applications and the Network Information Center is being developed at GSFC. GSFC will lead the NSI User Services, but NSI at Ames will continue to provide the User Services during the transition. The transition will be made as transparent as possible for the users. DECnet service will continue, but is now directly managed by NSI at Ames. NSI will continue to work closely with routing center managers at other NASA centers, and has formed a transition team to address the change in management. An NSI/DECnet working group had also been formed as a separate engineering group within NSI to plan the transition to Phase 5, DECnet's approach to Open System Integration (OSI). Transition is not expected for a year or more due to delays in produce releases. Plans to upgrade speeds in tail circuits and the backbone are underway. The proposed baseline service for new connections is up to 56 Kbps; 9.6 Kbps lines will gradually be upgraded as requirements dictate. NSI is in the process of consolidating protocol traffic, tail circuits, and the backbone. Currently NSI's backbone is fractional T1; NSI will go to full T1 service as soon as it is feasible.

  11. Existing Steel Railway Bridges Evaluation

    Science.gov (United States)

    Vičan, Josef; Gocál, Jozef; Odrobiňák, Jaroslav; Koteš, Peter

    2016-12-01

    The article describes general principles and basis of evaluation of existing railway bridges based on the concept of load-carrying capacity determination. Compared to the design of a new bridge, the modified reliability level for existing bridges evaluation should be considered due to implementation of the additional data related to bridge condition and behaviour obtained from regular inspections. Based on those data respecting the bridge remaining lifetime, a modification of partial safety factors for actions and materials could be respected in the bridge evaluation process. A great attention is also paid to the specific problems of determination of load-caring capacity of steel railway bridges in service. Recommendation for global analysis and methodology for existing steel bridge superstructure load-carrying capacity determination are described too.

  12. BUILDING "BRIDGES" WITH QUALITY ASSURANCE

    Science.gov (United States)

    The papr describes how, rather than building "bridges" across centuries, quality assurance (QA) personnel have the opportunity to build bridges across technical disciplines, between public and private organizations, and between different QA groups. As reviewers and auditors of a...

  13. Turning Simple Span into Complex Span: Time for Decay or Interference from Distractors?

    Science.gov (United States)

    Lewandowsky, Stephan; Geiger, Sonja M.; Morrell, Daniel B.; Oberauer, Klaus

    2010-01-01

    We investigated the effects of the duration and type of to-be-articulated distractors during encoding of a verbal list into short-term memory (STM). Distractors and to-be-remembered items alternated during list presentation, as in the complex-span task that underlies much of working-memory research. According to an interference model of STM, known…

  14. The Bridges Program.

    Science.gov (United States)

    Bohnen, Elizabeth; Klie, Judy

    This report describes BRIDGES, an employment equity special measures training program developed by the City of Toronto (Ontario, Canada). It was designed to help women employees move from their traditional jobs into trades, technical or operation (TTO) jobs within their own organization. The program is a combination of classroom sessions, shop…

  15. Bridging a Cultural Gap

    Science.gov (United States)

    Leviatan, Talma

    2008-01-01

    There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a…

  16. DOE Information Bridge

    CERN Document Server

    United States. Department of Energy. Office of Scientific and Technical Information

    DOE Information Bridge, a component of EnergyFiles, provides free, convenient, and quick access to full-text DOE research and development reports in physics, chemistry, materials, biology, environmental sciences, energy technologies, engineering, computer and information science, renewable energy, and other topics. This vast collection includes over 43,000 reports that have been received and processed by OSTI since January 1995.

  17. Bridge over troubled water?

    DEFF Research Database (Denmark)

    Svendsen, Gunnar Lind Haase; Nannestad, Peter; Svendsen, Gert Tinggaard

    2008-01-01

    The problem of integrating non-Western immigrants into Western welfare states is the focus of this paper. To address this issue, we suggest a social capital approach in which we apply the conceptual pair of bridging social capital (BR), which connects an individual to the broader social structure...

  18. Looking Beyond the Bridge

    DEFF Research Database (Denmark)

    Jahn, Elke; Rosholm, Michael

    We perform a comprehensive analysis of the stepping-stone effect of temporary agency employment on unemployed workers. Using the timing-of-events approach, we not only investigate whether agency employment is a bridge into regular employment but also analyze its effect on post-unemployment wages...

  19. Bridging the Technological Gap.

    Science.gov (United States)

    Lazow, Robert; And Others

    The aim of "Bridging the Technological Gap" (BTG), a federally funded demonstration project, is to use microcomputer technology in the rehabilitation of the psychiatrically disabled. Through the use of a custom designed microcomputer software package, clients receive remediation in areas of specific cognitive and behavioral deficits. The project…

  20. Building Bridges to China.

    Science.gov (United States)

    Wasta, Stephanie; Scott, Margaret

    1998-01-01

    Describes a theme cycle called "Building Bridges to China" developed for third grade students that focuses on the similarities between the lives of children and families in China and the United States. Explains that the theme cycle addresses the National Geography Standards and three of the National Council for the Social Studies standards. (CMK)

  1. Design and construction of scour protection for deep-water group pile foundation structures of two pylons in the Sutong Bridge project

    Institute of Scientific and Technical Information of China (English)

    He Ping; Guan Yijun; Zhang Xiongwen; Zhang Qun; Zhou Jianhua

    2009-01-01

    Sutong Bridge, as a world-record cable-stayed bridge with its main span exceeding 1 000 m constructed in Yangtze River estuary region in China, is located at a site with complicated hydrologic conditions and poor geotechnical conditions and therefore, scour protection will be a decisive factor for ensuring smooth and successful construction of this bridge. This paper, starting from structural description of deep-water group pile foundation, analyzes impact to the bridge safety introduced by scour and its protection and further presents different solutions of scour protection for foundation structures of this bridge.

  2. The geometry of inner spanning trees for planar polygons

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, Alexandr O; Tuzhilin, Alexey A [P.G. Demidov Yaroslavl State University, Yaroslavl (Russian Federation)

    2012-04-30

    We study the geometry of minimal inner spanning trees for planar polygons (that is, spanning trees whose edge-intervals lie in these polygons). We construct analogues of Voronoi diagrams and Delaunay triangulations, prove that every minimal inner spanning tree is a subgraph of an appropriate Delaunay triangulation, and describe the possible structure of the cells of such triangulations.

  3. The generalized minimum spanning tree polytope and related polytopes

    NARCIS (Netherlands)

    Pop, P.C.

    2001-01-01

    The Generalized Minimum Spanning Tree problem denoted by GMST is a variant of the classical Minimum Spanning Tree problem in which nodes are partitioned into clusters and the problem calls for a minimum cost tree spanning at least one node from each cluster. A different version of the problem, calle

  4. A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems

    NARCIS (Netherlands)

    Ciftci, B.B.; Tijs, S.H.

    2007-01-01

    In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari

  5. A Vertex Oriented Approach to Minimum Cost Spanning Tree Problems

    NARCIS (Netherlands)

    Ciftci, B.B.; Tijs, S.H.

    2007-01-01

    In this paper we consider spanning tree problems, where n players want to be connected to a source as cheap as possible. We introduce and analyze (n!) vertex oriented construct and charge procedures for such spanning tree situations leading in n steps to a minimum cost spanning tree and a cost shari

  6. The generalized minimum spanning tree polytope and related polytopes

    NARCIS (Netherlands)

    Pop, P.C.

    2001-01-01

    The Generalized Minimum Spanning Tree problem denoted by GMST is a variant of the classical Minimum Spanning Tree problem in which nodes are partitioned into clusters and the problem calls for a minimum cost tree spanning at least one node from each cluster. A different version of the problem, calle

  7. Revised Rules for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C.;

    This paper is based on research performed for the Highway Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: Concrete Bridges" It contains details of a methodology which can be used to generate Whole Life (WL) reliability profiles....... These WL reliability profiles may be used to establish revised rules for Concrete Bridges....

  8. The Bridges of Taishun County

    Institute of Scientific and Technical Information of China (English)

    MaJianhe

    2003-01-01

    The American film The Bridges of Madison County captured the imagination of many Chinese moviegoers with its bittersweet love story and scenes of rustic covered bridges. But the U.S. can't lay sole claim to such spectacular rural sights:China has its own county worldrenowned for unforgettable bridges.

  9. Influence of central buckle on suspension bridge dynamic characteristics and driving comfort

    Institute of Scientific and Technical Information of China (English)

    王达; 邓扬; 刘扬

    2015-01-01

    The central buckle, which is often used in a suspension bridge, can improve bridges’ performance in the actual operation condition. The influence of the central buckle on natural vibration characteristics and bridge-deck driving comfort of a long-span suspension bridge is studied by using a case study of Siduhe Suspension Bridge in China. Based on the finite element software ANSYS and independently complied program, the influence of the central buckle on the structure force-applied characteristics of a long-span suspension bridge has been explored. The results show that the huge increases of natural frequencies can result in the presence of central buckles because of the increases of bending and torsional rigidities. The central buckle basically makes the stiffening girders and cables within the triangular area covered as a relatively approximate rigid area. Hence, the central buckle can reduce the torsional displacement of the main girder. However, the increases of bending and torsional rigidities have little influence on the impact factor, which is obtained by using vehicle-bridge coupled vibration analysis. This means that the central buckle has little effect on the comfort indices. In addition, it is found that the central buckle can enhance the bridge deck’s driving stability due to the decrease of the torsional displacements of the main girder.

  10. Theoretical and experimental study on shear lag effect of partially cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    WU Gao-feng; XU Hong

    2005-01-01

    In order to resolve the traffic congestion problem, many cable-stayed bridges are designed with a large width to span ratio. This results in significant shear lag effect to cause nonuniform stress distribution along the flanges of the beam of bridge.This paper reports study on the shear lag effect of the Lanzhou Xiaoxihu Yellow River Bridge. A 3D finite element model of the bridge was developed and finite element analysis (FEA) was done to obtain the theoretical results. To evaluate the theoretical results, a scaled model was made to conduct static test in laboratory. The experiment results accorded with the results obtained by FEA. It is proved that FEA is an effective method to predict shear lag effect of bridges of this type.

  11. Risk Assessment for Bridges Safety Management during Operation Based on Fuzzy Clustering Algorithm

    Directory of Open Access Journals (Sweden)

    Xia Hanyu

    2016-01-01

    Full Text Available In recent years, large span and large sea-crossing bridges are built, bridges accidents caused by improper operational management occur frequently. In order to explore the better methods for risk assessment of the bridges operation departments, the method based on fuzzy clustering algorithm is selected. Then, the implementation steps of fuzzy clustering algorithm are described, the risk evaluation system is built, and Taizhou Bridge is selected as an example, the quantitation of risk factors is described. After that, the clustering algorithm based on fuzzy equivalence is calculated on MATLAB 2010a. In the last, Taizhou Bridge operation management departments are classified and sorted according to the degree of risk, and the safety situation of operation departments is analyzed.

  12. A New Multiconstraint Method for Determining the Optimal Cable Stresses in Cable-Stayed Bridges

    Directory of Open Access Journals (Sweden)

    B. Asgari

    2014-01-01

    Full Text Available Cable-stayed bridges are one of the most popular types of long-span bridges. The structural behaviour of cable-stayed bridges is sensitive to the load distribution between the girder, pylons, and cables. The determination of pretensioning cable stresses is critical in the cable-stayed bridge design procedure. By finding the optimum stresses in cables, the load and moment distribution of the bridge can be improved. In recent years, different research works have studied iterative and modern methods to find optimum stresses of cables. However, most of the proposed methods have limitations in optimising the structural performance of cable-stayed bridges. This paper presents a multiconstraint optimisation method to specify the optimum cable forces in cable-stayed bridges. The proposed optimisation method produces less bending moments and stresses in the bridge members and requires shorter simulation time than other proposed methods. The results of comparative study show that the proposed method is more successful in restricting the deck and pylon displacements and providing uniform deck moment distribution than unit load method (ULM. The final design of cable-stayed bridges can be optimised considerably through proposed multiconstraint optimisation method.

  13. A new multiconstraint method for determining the optimal cable stresses in cable-stayed bridges.

    Science.gov (United States)

    Asgari, B; Osman, S A; Adnan, A

    2014-01-01

    Cable-stayed bridges are one of the most popular types of long-span bridges. The structural behaviour of cable-stayed bridges is sensitive to the load distribution between the girder, pylons, and cables. The determination of pretensioning cable stresses is critical in the cable-stayed bridge design procedure. By finding the optimum stresses in cables, the load and moment distribution of the bridge can be improved. In recent years, different research works have studied iterative and modern methods to find optimum stresses of cables. However, most of the proposed methods have limitations in optimising the structural performance of cable-stayed bridges. This paper presents a multiconstraint optimisation method to specify the optimum cable forces in cable-stayed bridges. The proposed optimisation method produces less bending moments and stresses in the bridge members and requires shorter simulation time than other proposed methods. The results of comparative study show that the proposed method is more successful in restricting the deck and pylon displacements and providing uniform deck moment distribution than unit load method (ULM). The final design of cable-stayed bridges can be optimised considerably through proposed multiconstraint optimisation method.

  14. Simulation of multivariate diffusion bridges

    DEFF Research Database (Denmark)

    Bladt, Mogens; Finch, Samuel; Sørensen, Michael

    We propose simple methods for multivariate diffusion bridge simulation, which plays a fundamental role in simulation-based likelihood and Bayesian inference for stochastic differential equations. By a novel application of classical coupling methods, the new approach generalizes a previously...... proposed simulation method for one-dimensional bridges to the mulit-variate setting. First a method of simulating approzimate, but often very accurate, diffusion bridges is proposed. These approximate bridges are used as proposal for easily implementable MCMC algorithms that produce exact diffusion bridges...

  15. Bragg grating structural sensing system for bridge monitoring

    Science.gov (United States)

    Measures, Raymond M.; Alavie, A. Tino; Maaskant, Robert; Ohn, Myo M.; Karr, Shawn E.; Huang, Shang Yuan

    1994-09-01

    Corrosion of steel within bridges and other large concrete structures has become a serious problem and consequently there is growing interest in replacing the steel within such structures with carbon fiber based composite materials. The first highway bridge in the world to use carbon fiber composite prestressing tendons was constructed and opened to the public in the fall of 1993. This two span bridge was also unique in another respect, it is the first highway bridge in the world to have been built with a set of fiber optic Bragg grating sensors structurally integrated into several of its precast concrete deck support girders. A four-channel fiber laser sensor demodulation system that was rugged, compact and transportable was developed for this project. This demodulation system monitored the changes in the internal strain on all three types (steel and two types of carbon fiber composite) of prestressing tendons over several months. The same structurally integrated fiber optic sensing system has also been used to measure the change in the internal strain within the deck girders arising from both static and dynamic loading of the bridge with a large truck.

  16. Bamboo Reinforced Concrete Truss Bridge for Rural Infrastructure

    Directory of Open Access Journals (Sweden)

    D. Nuralinah

    2014-04-01

    Full Text Available Bamboo is one of a potential renewable construction material in the village. Bamboo is known to have a high mechanical strength in direction of the fibers. The weakness of bamboo in lateral direction of the fiber could be solved by constructing a composite structure with the concrete. The appropriate construction with hold the loads in axial direction is a truss structure. In a bamboo concrete truss structure, the bars are composed from the concrete column with a bamboo reinforcement. The research studies about the performance of the bridge and the effect of loading position on the strain and deformation of bamboo reinforced concrete truss bridge. The bridge whose span and width are respectively 1.5 m and 1.2 m was prepared. Load applied to the truss bridge conducted by using vehicle load changes with position. Mounting the strains gauge in bamboo reinforcement of primary truss is to observe the strain. The LVDT is used to observe the deflection of the truss bridge. The results show that the loading position influences the strain and deformation as well as a theoretical view.

  17. Construction of the world's first continuous PC steel composite extradosed bridge. New Meishin Expressway Kiso River Bridge and Ibi River Bridge; Sekaihatsu no PC {center_dot} ko fukugo renzoku ekusutora dozudo kyo no seko. Dai 2 meishin kosoku doro Kisogawa kyo {center_dot} Ibigawa kyo

    Energy Technology Data Exchange (ETDEWEB)

    Mizuguchi, Kazuyuki; Nakasu, Makoto [Japan Highway Public Corpration, Tokyo (Japan)

    1999-09-10

    Kiso River Bridge and Ibi River bridge in the Second Meishin Expressway are the bridges lying across the river mouths of Kiso River and Ibi River which are two of the biggest rivers in Japan. Since a span length of 160m or more is necessary when constructing the bridges, comparison examinations in respect to bridge forms that can secure a long span were carried out. As a result, the world's first continuous PC steel composite extradosed bridge was adopted. The construction works of these two bridges were each divided into the east and the west works, thus totally four constructions works were ordered. Now both the two bridges are approaching the most active period of their superstructure works. In this paper, summary of the superstructure works of these two bridges is described and the situation of concrete girder portions operated hitherto is introduced. Particularly, for the concrete girder portions in composite structures, an extrodosed form is employed to arrange PC members outside the girders so as to use them more effectively and make prestress force act on a main girder at a great eccentricity. (NEDO)

  18. Spanning the Home/Work Creative Space

    DEFF Research Database (Denmark)

    Davis, Lee N.; Davis, Jerome; Hoisl, Karin

    This paper explores the link between employee leisure time activities and the value of their creative output. We argue that leisure time activities – both in general, and specifically with regard to the employee’s choice of hobbies – both illuminate and shape the attitudes and attributes the empl......This paper explores the link between employee leisure time activities and the value of their creative output. We argue that leisure time activities – both in general, and specifically with regard to the employee’s choice of hobbies – both illuminate and shape the attitudes and attributes...... the employee brings to work. Based on Woodman et al.’s (1993) “interactionist perspective” on organizational creativity, supplemented by literature on search and knowledge re/combination, we explore whether and how leisure time activities can span the creative space between the employee’s home and workplace...... – given the range of multi-level inputs that may also contribute to workplace creativity. We use original survey data comprising 4,138 inventions from 21 European countries, the United States and Japan, in all major industries. Organizational creativity is measured by the asset value of the patent...

  19. Recommendations for the shear assessment of reinforced concrete slab bridges from experiments

    NARCIS (Netherlands)

    Lantsoght, E.O.L.; Van der Veen, C.; Walraven, J.C.; De Boer, A.

    2013-01-01

    Upon assessment of existing reinforced concrete short-span solid slab bridges according to the recently implemented Eurocodes that include more conservative shear capacity provisions and heavier axle loads, a number of these structures were found to be shear-critical. The results from recent

  20. Bridging as Coercive Accommodation

    CERN Document Server

    Bos, J W; Mineur, A M; Bos, Johan; Buitelaar, Paul; Mineur, Anne-Marie

    1995-01-01

    In this paper we discuss the notion of "bridging" in Discourse Representation Theory as a tool to account for discourse referents that have only been established implicitly, through the lexical semantics of other referents. In doing so, we use ideas from Generative Lexicon theory, to introduce antecedents for anaphoric expressions that cannot be "linked" to a proper antecedent, but that do not need to be "accommodated" because they have some connection to the network of discourse referents that is already established.

  1. Bridging Classroom Language Ethnography

    OpenAIRE

    GRENFELL, MICHAEL JAMES

    2012-01-01

    PUBLISHED Paper #5: Bridging Classroom Language Ethnography, New Literacy Studies and Bourdieu?s Social Philosophy: Principles and Practice The purpose of this paper is to analyze and synthesize the various ways that classroom language ethnography, NLS, and Bourdieu?s social philosophy, were integrated. The goal of the analysis and synthesis is to provide a fresh perspective and fruitful insights on literacy in all its manifestations that provides the foundations for a more robust...

  2. Environmental life cycle assessment comparison between two bridge types: reinforced concrete bridge and steel composite bridge

    DEFF Research Database (Denmark)

    Du, Guangli; Karoumi, Raid

    2013-01-01

    not been integrated into the decision-making process. This paper presents a systematic LCA method for quantifying the environmental impacts for bridges. The comparison study is performed between a reinforced concrete bridge and a steel bridge as an alternative design, with several key maintenance and EOL......The concept of sustainable construction has attracted an increased attention. Bridge infrastructures and their belonged construction activities consume considerable material and energy, which is responsible for large environmental burdens. However, the environmental assessment of bridges has...

  3. Full scale monitoring of wind and traffic induced response of a suspension bridge

    Directory of Open Access Journals (Sweden)

    Cheynet Etienne

    2015-01-01

    Full Text Available This paper presents a full-scale analysis of wind and traffic-induced vibrations of a long-span suspension bridge in complex terrain. Several wind and acceleration sensors have been installed along the main span on Lysefjord Bridge in Norway. In the present study, three days of continuous records are analysed. Traffic-induced vibrations are dominant at low and moderated wind speed, with non-negligible effects on the overall bridge response for heavy vehicles only. Traffic and wind-induced vibrations are compared in terms of root mean square of the acceleration response, and three simples approaches are proposed to isolate records dominated by wind-induced vibration. The first one relies on the separation of nocturnal and diurnal samples. The second one is based on the evaluation of the time-varying root mean square of the acceleration response. The last one evaluates the relative importance of the high frequency domain of the acceleration bridge response. It appears that traffic-induced vibrations may have to be taken into account for the buffeting analysis of long-span bridge under moderated wind.

  4. Spanning Trees and bootstrap reliability estimation in correlation based networks

    CERN Document Server

    Tumminello, M; Lillo, F; Micciché, S; Mantegna, R N

    2006-01-01

    We introduce a new technique to associate a spanning tree to the average linkage cluster analysis. We term this tree as the Average Linkage Minimum Spanning Tree. We also introduce a technique to associate a value of reliability to links of correlation based graphs by using bootstrap replicas of data. Both techniques are applied to the portfolio of the 300 most capitalized stocks traded at New York Stock Exchange during the time period 2001-2003. We show that the Average Linkage Minimum Spanning Tree recognizes economic sectors and sub-sectors as communities in the network slightly better than the Minimum Spanning Tree does. We also show that the average reliability of links in the Minimum Spanning Tree is slightly greater than the average reliability of links in the Average Linkage Minimum Spanning Tree.

  5. Full Model Wind Tunnel Study on the Xia-Zhang Bridge Under Operation Stage

    Directory of Open Access Journals (Sweden)

    Ayad T. Saeed

    2010-01-01

    Full Text Available Problem statement: Long-span cable-stayed bridges under service and particular construction conditions are very susceptible to wind action due to their great flexibility, so the aerodynamic stability is becoming a major concern in the design and construction phrases. Cable-stayed bridges may exhibit wind-induced vibration phenomena such as flutter, buffeting and vortex oscillation under wind excitation. The study concentrated on the issues concerning the aerodynamic response of Xia-Zhang cable-stayed Bridge to make it safe and stable under wind action. Although there have been accumulating experience in the building of cable-stayed bridges and research on wind-resistant stability in Chinese Mainland, most of the research focuses on inland cable-stayed bridges or littoral ones of mid-length, but not on littoral ones whose main span is over 600 m. Therefore, wind-resistant performance research of north branch bridge of Xia-Zhang cross-sea Bridges is very necessary and important for its wind-resistant stability, safety and applicability in the operation condition. Approach: This study mainly presented the wind tunnel test program of the Xia-Zhang Bridge aeroelastic full model, including test method, test contents, test results and so on. Results: The test results contained Root Mean Square (RMS of accelerations and displacements as well as average values of displacements. Conclusion: The conclusions were as follows: (a In the uniform flow field, under the condition of entire bridge without rail may vibration divergence occur when α = 3°, V>122 m sec-1. (b No vortex-induced vibration with extreme amplitudes or static collapsing was detected in all the testing conditions. (c In the turbulent flow field, there were very obvious buffeting phenomena. Responses to turbulence are quite intense.

  6. The active-bridge oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Wessendorf, K.O.

    1998-07-01

    This paper describes the Active-Bridge Oscillator (ABO), a new concept in high-stability oscillator design. The ABO is ab ridge-type oscillator design that is easly to design and overcomes many of the operational and design difficulties associated with standard bridge oscillator designs. The ABO will oscillate with a very stable output amplitude over a wide range of operating conditions without the use of an automatic-level-control (ALC). A standard bridge oscillator design requires an ALC to maintain the desired amplitude of oscillation. for this and other reasons, bridge oscilaltors are not used in mainstream designs. Bridge oscillators are generally relegated to relatively low-volume, high-performance applications. The Colpitts and Pierce designs are the most popular oscillators but are typically less stable than a bridge-type oscillator.

  7. Vulnerability of bridges to fire

    DEFF Research Database (Denmark)

    Giuliani, Luisa; Crosti, C.; Gentili, F.

    2012-01-01

    Even if recent effort in developing methodology and measures for design structures against fire and explosions has been mostly focused on buildings, bridges can also be very sensitive to those actions, as witnesses by some recent bridge accidents, which caused major economic losses and also...... endangered people safety in few cases. Purpose of this paper is making a focus on the state of the art of the research and current regulations concerning the response of bridges to fire. Several cases of bridge fires are reported and a focus is made on the occurrence and consequence of bridge fires......, considering both the costs deriving by structural damages and by limited serviceability and other indirect societal aspects. Few cases of recent bridge fire are reviewed in detail and structural consequences are highlighted, distinguishing between damages directly induced by fire and damages induced by local...

  8. Developmental Changes in the Visual Span for Reading

    OpenAIRE

    Kwon, MiYoung; Legge, Gordon E; Dubbels, Brock R.

    2007-01-01

    The visual span for reading refers to the range of letters, formatted as in text, that can be recognized reliably without moving the eyes. It is likely that the size of the visual span is determined primarily by characteristics of early visual processing. It has been hypothesized that the size of the visual span imposes a fundamental limit on reading speed (Legge, Mansfield, & Chung, 2001). The goal of the present study was to investigate developmental changes in the size of the visual span i...

  9. MINIMUM CONGESTION SPANNING TREES IN BIPARTITE AND RANDOM GRAPHS

    Institute of Scientific and Technical Information of China (English)

    M.L Ostrovskii

    2011-01-01

    The first problem considered in this article reads: is it possible to find upper estimates for the spanning tree congestion in bipartite graphs, which are better than those for general graphs? It is proved that there exists a bipartite version of the known graph with spanning tree congestion of order n3/2, where n is the number of vertices. The second problem is to estimate spanning tree congestion of random graphs. It is proved that the standard model of random graphs cannot be used to find graphs whose spanning tree congestion has order greater than n3/2.

  10. Big data and high-performance analytics in structural health monitoring for bridge management

    Science.gov (United States)

    Alampalli, Sharada; Alampalli, Sandeep; Ettouney, Mohammed

    2016-04-01

    Structural Health Monitoring (SHM) can be a vital tool for effective bridge management. Combining large data sets from multiple sources to create a data-driven decision-making framework is crucial for the success of SHM. This paper presents a big data analytics framework that combines multiple data sets correlated with functional relatedness to convert data into actionable information that empowers risk-based decision-making. The integrated data environment incorporates near real-time streams of semi-structured data from remote sensors, historical visual inspection data, and observations from structural analysis models to monitor, assess, and manage risks associated with the aging bridge inventories. Accelerated processing of dataset is made possible by four technologies: cloud computing, relational database processing, support from NOSQL database, and in-memory analytics. The framework is being validated on a railroad corridor that can be subjected to multiple hazards. The framework enables to compute reliability indices for critical bridge components and individual bridge spans. In addition, framework includes a risk-based decision-making process that enumerate costs and consequences of poor bridge performance at span- and network-levels when rail networks are exposed to natural hazard events such as floods and earthquakes. Big data and high-performance analytics enable insights to assist bridge owners to address problems faster.

  11. Wind-induced vibration control of bridges using liquid column damper

    Institute of Scientific and Technical Information of China (English)

    薛素铎; 高赞明; 徐幼麟

    2002-01-01

    The potential application of tuned liquid column damper (TLCD) for suppressing wind-induced vibration of long span bridges is explored in this paper. By installing the TLCD in the bridge deck, a mathematical model for the bridge-TLCD system is established. The governing equations of the system are developed by considering all three displacement components of thc deck in vertical, lateral, and torsional vibrations, in which the interactions between the bridge deck, the TLCD, the aeroelastic forces, and the aerodynamic forces are fully reflected. Both buffeting and flutter analyses are carried out. The buffeting analysis is performed through random vibration approach, and a critical flutter condition is identified from flutter analysis. A numerical example is presented to demonstrate the control effectiveness of the damper and it is shown that the TLCD can be an effective device for suppressing wind-induced vibration of long span bridges, either for reducing the buffeting response or increasing the critical flutter wind velocity of the bridge.

  12. Environmental variability study on the measured responses of Runyang Cablestayed Bridge using wavelet packet analysis

    Institute of Scientific and Technical Information of China (English)

    DING YouLiang; LI AiQun; LIU Tao

    2008-01-01

    The structural damage alarming method based on wavelet packet energy spectrum (WPES) for long-span cable-stayed bridges is presented through combination of ambient vibration test and wavelet packet analysis.The environmental variability in the measured WPES and damage alarming indices ERVD of the Runyang Ca-ble-stayed Bridge are discussed in detail using the wavelet packet analysis of the measured acceleration responses of the bridge under daily environmental condi-tions.The analysis results reveal that the actual environmental conditions includ-ing traffic Ioadings,environmental temperature and typhoon Ioadings have re-markable correlations with the measured WPES.The changes of environmental temperature have a long-term trend influence on the WPES,while the influences of traffic and typhoon Ioadings on the measured WPES of the bridge present instan-taneous changes because of the nonstationary properties of the Ioadings.The analysis results of the measured responses further reveal that the damage alarm-ing indices ERVD can sensitively reflect the influences of environmental tempera-ture and typhoon Ioadings on the dynamic properties of Runyang Cable-stayed Bridge.Therefore,the proposed structural damage alarming indices ERVD under ambient vibrations are suitable for real-time damage alarming for long-span ca-ble-stayed bridges.

  13. Environmental variability study on the measured responses of Runyang Cablestayed Bridge using wavelet packet analysis

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The structural damage alarming method based on wavelet packet energy spectrum (WPES) for long-span cable-stayed bridges is presented through combination of ambient vibration test and wavelet packet analysis. The environmental variability in the measured WPES and damage alarming indices ERVD of the Runyang Cable-stayed Bridge are discussed in detail using the wavelet packet analysis of the measured acceleration responses of the bridge under daily environmental conditions. The analysis results reveal that the actual environmental conditions including traffic loadings, environmental temperature and typhoon loadings have remarkable correlations with the measured WPES. The changes of environmental temperature have a long-term trend influence on the WPES, while the influences of traffic and typhoon loadings on the measured WPES of the bridge present instantaneous changes because of the nonstationary properties of the loadings. The analysis results of the measured responses further reveal that the damage alarming indices ERVD can sensitively reflect the influences of environmental temperature and typhoon loadings on the dynamic properties of Runyang Cable-stayed Bridge. Therefore, the proposed structural damage alarming indices ERVD under ambient vibrations are suitable for real-time damage alarming for long-span cable-stayed bridges.

  14. Detection of a Coherent Magnetic Field in the Magellanic Bridge through Faraday Rotation

    Science.gov (United States)

    Kaczmarek, J. F.; Purcell, C. R.; Gaensler, B. M.; McClure-Griffiths, N. M.; Stevens, J.

    2017-01-01

    We present an investigation into the magnetism of the Magellanic Bridge, carried out through the observation of Faraday rotation towards 167 polarized extragalactic radio sources spanning the continuous frequency range of 1.3 - 3.1 GHz with the Australia Telescope Compact Array. Comparing measured Faraday depth values of sources `on' and `off' the Bridge, we find that the two populations are implicitly different. Assuming that this difference in populations is due to a coherent field in the Magellanic Bridge, the observed Faraday depths indicate a median line-of-sight coherent magnetic-field strength of B∥ ≃ 0.3 μG directed uniformly away from us. Motivated by the varying magnitude of Faraday depths of sources on the Bridge, we speculate that the coherent field observed in the Bridge is a consequence of the coherent magnetic fields from the Large and SMCs being pulled into the tidal feature. This is the first observation of a coherent magnetic field spanning the entirety of the Magellanic Bridge and we argue that this is a direct probe of a `pan-Magellanic' field.

  15. Bridge Aesthetics and Structural Honesty

    DEFF Research Database (Denmark)

    Gimsing, Niels Jørgen

    1999-01-01

    In bridges the overall form must be chosen with due respect to the transmission of forces if efficient structures shall be created, The design must therefore be governed by experienced structural engineers - in some cases assisted by aesthetic advisers on specific issues. Some basic requirements...... decisive for choosing the form of trusses, arches and cable-stayed bridges are outlined, and several examples show bridges designed without giving priority to the structural aspects....

  16. Morphological aspects of myocardial bridges.

    Science.gov (United States)

    Lujinović, Almira; Kulenović, Amela; Kapur, Eldan; Gojak, Refet

    2013-11-01

    Although some myocardial bridges can be asymptomatic, their presence often causes coronary disease either through direct compression of the "tunnel" segment or through stimulation and accelerated development of atherosclerosis in the segment proximally to the myocardial bridge. The studied material contained 30 human hearts received from the Department of Anatomy. The hearts were preserved 3 to 5 days in 10% formalin solution. Thereafter, the fatty tissue was removed and arterial blood vessels prepared by careful dissection with special reference to the presence of the myocardial bridges. Length and thickness of the bridges were measured by the precise electronic caliper. The angle between the myocardial bridge fibre axis and other axis of the crossed blood vessel was measured by a goniometer. The presence of the bridges was confirmed in 53.33% of the researched material, most frequently (43.33%) above the anterior interventricular branch. The mean length of the bridges was 14.64 ± 9.03 mm and the mean thickness was 1.23 ± 1.32 mm. Myocardial bridge fibres pass over the descending blood vessel at the angle of 10-90 degrees. The results obtained on a limited sample suggest that the muscular index of myocardial bridge is the highest for bridges located on RIA, but that the difference is not significant in relation to bridges located on other branches. The results obtained suggest that bridges located on other branches, not only those on RIA, could have a great contractive power and, consequently, a great compressive force, which would be exerted on the wall of a crossed blood vessel.

  17. Modular FRP Composite Bridge Deck

    OpenAIRE

    ECT Team, Purdue

    2007-01-01

    The bridge infrastructure of the United States is in constant need of repair and rehabilitation. It is reported that 43% of the bridges in the USA have been identified as being structurally deficient or functionally obsolete due to corrosion. SuperdeckTM, a non-corrosive fiber reinforced polymer (FRP) composite bridge deck. The Deck is designed and engineered into a lightweight, strong and rigid structure that will not corrode. The deck sections, composed of hexagon and double-trapezoid profi...

  18. Bridging Literature and Linguistics

    Directory of Open Access Journals (Sweden)

    Abdul Wahab

    2002-01-01

    Full Text Available Abstract: Two majors linguistics and literature in the schools of letters both in the state and private universities throughout Indonesia are commonly separated sharply. Courses of literature in the Department of Linguistics are offered minimally, such that the students of linguistics are not given a conducive atmosphere to express their literary appreciation. Likewise, courses of linguistics in the Department of Literature are very restricted, so that the students of literature are unable to analyze literary works from the points of linguistic view. This paper tries to bridge linguistics and literature. The attempt to bridge linguistics and literature is based on three postulates: (I literature consists of linguistic objects designed with an artistic end, (2 linguistic objects are formal objects, and (3 a formal account of linguistic object designed with an artistic end approximates a formal account of that artistic design. Two major directions in the approaches and emphases will be presented in the paper exogenous and endogenous. Exogenous approach tries to search for adequate description of (1 poetic language as contrasted with ordinary language, (2 language of a particular author contrasted with that of other authors, and (3 a particular literary work contrasted with other works of the same author. This part touches upon three areas of exogenous approach isolation, description, and characterization. Endogenous, on the hand, is based upon an assumption that a writer exhibits, probably without realizing it, certain systematic preferences for particular aspects of linguistic patterns. Planning a bridge between linguistics and literature is by no means without problems. Therefore, this paper also presents some possible solutions.

  19. Bridging Literature and Linguistics

    Directory of Open Access Journals (Sweden)

    Abdul Wahab

    2003-01-01

    Full Text Available Two majors linguistics and literature in the schools of letters both in the state and private universities throughout Indonesia are commonly separated sharply. Courses of literature in the Department of Linguistics are offered minimally, such that the students of linguistics are not given a conducive atmosphere to express their literary appreciation. Likewise, courses of linguistics in the Department of Literature are very restricted, so that the students of literature are unable to analyze literary works from the points of linguistic view. This paper tries to bridge linguistics and literature. The attempt to bridge linguistics and literature is based on three postulates: (1 literature consists of linguistic objects designed with an artistic end, (2 linguistic objects are formal objects, and (3 a formal account of linguistic object designed with an artistic end approximates a formal account of that artistic design. Two major directions in the approaches and emphases will be presented in the paper exogenous and endogenous. Exogenous approach tries to search for adequate description of (1 poetic language as contrasted with ordinary language, (2 language of a particular author contrasted with that of other authors, and (3 a particular literary work contrasted with other works of the same author. This part touches upon three areas of exogenous approach isolation, description, and characterization. Endogenous, on the hand, is based upon an assumption that a writer exhibits, probably without realizing it, certain systematic preferences for particular aspects of linguistic patterns. Planning a bridge between linguistics and literature is by no means without problems. Therefore, this paper also presents some possible solutions.

  20. Human-simulated intelligent control of train braking response of bridge with MRB

    Science.gov (United States)

    Li, Rui; Zhou, Hongli; Wu, Yueyuan; Wang, Xiaojie

    2016-04-01

    The urgent train braking could bring structural response menace to the bridge under passive control. Based on the analysis of breaking dynamics of a train-bridge vibration system, a magnetorheological elastomeric bearing (MRB) whose mechanical parameters are adjustable is designed, tested and modeled. A finite element method (FEM) is carried out to model and optimize a full scale vibration isolation system for railway bridge based on MRB. According to the model above, we also consider the effect of different braking stop positions on the vibration isolation system and classify the bridge longitudinal vibration characteristics into several cases. Because the train-bridge vibration isolation system has multiple vibration states and strongly coupling with nonlinear characteristics, a human-simulated intelligent control (HSIC) algorithm for isolating the bridge vibration under the impact of train braking is proposed, in which the peak shear force of pier top, the displacement of beam and the acceleration of beam are chosen as control goals. The simulation of longitudinal vibration control system under the condition of train braking is achieved by MATLAB. The results indicate that different braking stop positions significantly affect the vibration isolation system and the structural response is the most drastic when the train stops at the third cross-span. With the proposed HSIC smart isolation system, the displacement of bridge beam and peak shear force of pier top is reduced by 53.8% and 34.4%, respectively. Moreover, the acceleration of bridge beam is effectively controlled within limited range.

  1. Parametric Study on Dynamic Response of Fiber Reinforced Polymer Composite Bridges

    Directory of Open Access Journals (Sweden)

    Woraphot Prachasaree

    2015-01-01

    Full Text Available Because of high strength and stiffness to low self-weight ratio and ease of field installation, fiber reinforced polymer (FRP composite materials are gaining popularity as the materials of choice to replace deteriorated concrete bridge decks. FRP bridge deck systems with lower damping compared to conventional bridge decks can lead to higher amplitudes of vibration causing dynamically active bridge deck leading serviceability problems. The FRP bridge models with different bridge configurations and loading patterns were simulated using finite element method. The dynamic response results under varying FRP deck system parameters were discussed and compared with standard specifications of bridge deck designs under dynamic loads. In addition, the dynamic load allowance equation as a function of natural frequency, span length, and vehicle speed was proposed in this study. The proposed dynamic load allowance related to the first flexural frequency was presented herein. The upper and lower bounds’ limits were established to provide design guidance in selecting suitable dynamic load allowance for FRP bridge systems.

  2. Flutter Derivatives Identification and Aerodynamic Performance of an Optimized Multibox Bridge Deck

    Directory of Open Access Journals (Sweden)

    Zhida Wang

    2016-01-01

    Full Text Available The bridge deck sections used for long-span suspension bridges have evolved through the years, from the compact box deck girders geometrical configurations to twin-box and three-box bridge decks sections. The latest generation of split and multiple-box bridge decks proved to have better aerodynamic behavior; thus further optimization methods are sought for such geometrical configurations. A new type of multibox bridge deck, consisting of four aerodynamically shaped deck boxes, two side decks for the traffic lanes and two middle decks for the railway traffic, connected between them by stabilizing beams, was tested in the wind tunnel for identifying the flutter derivatives and to verify the aerodynamic performance of the proposed multibox deck. Aerodynamic static force coefficients were measured for the multibox bridge deck model, scaled 1 : 80, for Reynolds numbers up to 5.1 × 105, under angles of attack between −8° and 8°. Iterative Least Squares (ILS method was employed for identifying the flutter derivatives of the multibox bridge deck model, based on the results obtained from the free vibration tests and based on the frequency analysis the critical flutter wind speed for the corresponding prototype of the multibox bridge was estimated at 188 m/s.

  3. Assessment of seismic performance of skew reinforced concrete box girder bridges

    Science.gov (United States)

    Abdel-Mohti, Ahmed; Pekcan, Gokhan

    2013-12-01

    The seismic vulnerability of highway bridges remains an important problem and has received increased attention as a consequence of unprecedented damage observed during several major earthquakes. A significant number of research studies have examined the performance of skew bridges under service and seismic loads. The results of these studies are particularly sensitive to modeling assumptions in view of the interacting parameters. In the present study, three-dimensional improved beam-stick models of two-span highway bridges with skew angles varying from 0° to 60° are developed to investigate the seismic response characteristics of skew box girder bridges. The relative accuracy of beam-stick models is verified against counterpart finite element models. The effect of various parameters and conditions on the overall seismic response was examined such as skew angle, ground motion intensity, soil condition, abutment support conditions, bridge aspect ratio, and foundation-base conditions. The study shows that the improved beam-stick models can be used to conduct accurate nonlinear time history analysis of skew bridges. Skew angle and interacting parameters were found to have significant effect on the behavior of skewed highway bridges. Furthermore, the performance of shear keys may have a predominant effect on the overall seismic response of the skew bridges.

  4. Field dynamic testing on a Cyprus concrete highway bridge using Wireless Sensor Network (WSN)

    Science.gov (United States)

    Votsis, Renos A.; Kyriakides, Nicholas; Tantele, Elia A.; Chrysostomou, Christis Z.; Onoufriou, Toula

    2014-08-01

    The aims of the bridge management authorities are to ensure that bridges fulfil their purpose and functionality during their design life. So, it is important to identify and quantify the deterioration of the structural condition early so that a timely application of an intervention will avoid more serious problems and increased costs at a later stage. A measure to enhance the effectiveness of the existing structural evaluation by visual inspection is instrumental monitoring using sensors. The activities performed in this process belong to the field of Structural Health Monitoring (SHM). The SHM offers opportunities for continuous or periodic monitoring on bridges and technological advances allow nowadays the employment of wireless sensors networks (WSN) for this task. A SHM application using WSN was implemented on a multi-span reinforced concrete (RC) highway bridge in Limassol with the objective to study its dynamic characteristics and performance. Part of the specific bridge will be replaced and this offered a unique opportunity for measurements before and after construction so that apparent changes in the dynamic characteristics of the bridge will be identified after the repairing work. The measurements provided indications on the frequencies and mode shapes of the bridge and the response amplitude during the passing of traffic. The latter enabled the investigation of the dependency of the bridge's structural damping to the amplitude of vibration induced by the passing of traffic. The results showed that as the excitation increases the magnitude of modal damping increases as well.

  5. A parameter inversion for sea bridge based on high-resolution polarimetric synthetic aperture radar

    Institute of Scientific and Technical Information of China (English)

    LIU Genwang; ZHANG Jie; ZHANG Xi; MENG Junmin; WANG Guoyu

    2016-01-01

    Each reflection return of a bridge over water is displayed as wide stripe in a high-resolution synthetic aperture radar (SAR) image, which lead to difficulties in a parameter inversion. Therefore, a method of bridge parameter inversion is proposed for high-resolution full polarimetric SAR (PolSAR). First, the single, double and triple-bounce returns from each component of the bridge are distinguished by the polarization scattering features. Then the reasons which lead to the backscatter echoes of the bridge over water being displayed as stripes are analyzed, using a principle of microwave reflection, as well as an extraction method for each reflection return, and a parameter retrieval method is obtained. Finally, the parameters of the bridge, including the height (top and bottom surfaces of the sea bridge), width, thickness, span, and height of the bridge tower, are retrieved using full polarimetric AIRSAR data. When a comparison of the measured data is completed, the results indicate that the proposed method can invert the parameters with a high accuracy, and that the inversion error of the bridge height (bottom surface) is only 1.3%. Moreover, the results also show that for the high-resolution SAR, the C and L-band images have the same ability in regards to parameter retrieval.

  6. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst...

  7. Bridging The Inferential Gap

    Science.gov (United States)

    Stewart, Walter F.; Shah, Nirav R.; Selna, Mark J.; Paulus, Ronald A.; Walker, James M.

    2009-01-01

    Most clinical decisions involve bridging the inferential gap: Clinicians are required to “fill in” where they lack knowledge or where no knowledge yet exists. In this context we consider how the inferential gap is a product, in part, of how knowledge is created, the limits to gaining access to such knowledge, and the variable ways in which knowledge is translated into decisions. We consider how electronic health records (EHRs) will help narrow this gap by accelerating the creation of evidence relevant to everyday practice needs and facilitating real-time use of knowledge in practice. PMID:17259202

  8. Thermal bridges of modern windows

    DEFF Research Database (Denmark)

    Hansen, Ernst Jan de Place; Møller, Eva B.; Nielsen, Anker

    2013-01-01

    With its focus on reduced energy consumption, contemporary housing construction requires a highly insulated and airtight building envelope with as few thermal bridges as possible.Windows must be carefully designed, as thermal bridges can lead to surface condensation or mold growth, even if the wi......With its focus on reduced energy consumption, contemporary housing construction requires a highly insulated and airtight building envelope with as few thermal bridges as possible.Windows must be carefully designed, as thermal bridges can lead to surface condensation or mold growth, even...

  9. Modelling railway bridge asset management

    OpenAIRE

    Le, Bryant Linh Hai

    2014-01-01

    The UK has a long history in the railway industry with a large number of railway assets. Railway bridges form one of the major asset groups with more than 35,000 bridges. The majority of the bridge population are old being constructed over 100 years ago. Many of the bridges were not designed to meet the current network demand. With an expected increasing rate of deterioration due to the increasing traffic loads and intensities, the management authorities are faced with the difficult task of k...

  10. Analysis and assessment of bridge health monitoring mass data—progress in research/development of "Structural Health Monitoring"

    Institute of Scientific and Technical Information of China (English)

    LI AiQun; DING YouLiang; WANG Hao; GUO Tong

    2012-01-01

    The "Structural Health Monitoring" is a project supported by National Natural Science Foundation for Distinguished Young Scholars of China (Grant No.50725828).To meet the urgent requirements of analysis and assessment of mass monitoring data of bridge environmental actions and structural responses,the monitoring of environmental actions and action effect modeling methods,dynamic performance monitoring and early warning methods,condition assessment and operation maintenance methods of key members are systematically studied in close combination with structural characteristics of long-span cable-stayed bridges and suspension bridges.The paper reports the progress of the project as follows.(1) The environmental action modeling methods of long-span bridges are established based on monitoring data of temperature,sustained wind and typhoon.The action effect modeling methods are further developed in combination with the multi-scale baseline finite element modeling method for long-span bridges.(2) The identification methods of global dynamic characteristics and internal forces of cables and hangers for long-span cable-stayed bridges and suspension bridges are proposed using the vibration monitoring data,on the basis of which the condition monitoring and early warning methods of bridges are developed using the environmental-condition-normalization technique.(3) The analysis methods for fatigue loading effect of welded details of steel box girder,temperature and traffic loading effect of expansion joint are presented based on long-term monitoring data of strain and beam-end displacement,on the basis of which the service performance assessment and remaining life prediction methods are developed.

  11. The use of passwords to introduce theconcepts of spanning set and span

    Directory of Open Access Journals (Sweden)

    Andrea Cárcamo

    2017-01-01

    Full Text Available The aim of this paper is to present a proposal for teaching linear algebra based on heuristic of emergent models and mathematical modelling. This proposal begins with a problematic situation  related  to  the  creation  and  use  of  secure  passwords,  which  leads  first-year  students  of  engineering  toward  the  construction  of  the  concepts  of  spanning  set  and  span. The  proposal  is  designed  from  the  results  of  the  two  cycles  of  experimentation  teaching, design-based  research,  which  give  evidence  that  allows  students  to  progress  from  a  situation in a real context to the concepts of linear algebra. This proposal, previously adapted, could have similar results when applied to another group of students.

  12. Identifying sexual differentiation genes that affect Drosophila life span

    Directory of Open Access Journals (Sweden)

    Tower John

    2009-12-01

    Full Text Available Abstract Background Sexual differentiation often has significant effects on life span and aging phenotypes. For example, males and females of several species have different life spans, and genetic and environmental manipulations that affect life span often have different magnitude of effect in males versus females. Moreover, the presence of a differentiated germ-line has been shown to affect life span in several species, including Drosophila and C. elegans. Methods Experiments were conducted to determine how alterations in sexual differentiation gene activity might affect the life span of Drosophila melanogaster. Drosophila females heterozygous for the tudor[1] mutation produce normal offspring, while their homozygous sisters produce offspring that lack a germ line. To identify additional sexual differentiation genes that might affect life span, the conditional transgenic system Geneswitch was employed, whereby feeding adult flies or developing larvae the drug RU486 causes the over-expression of selected UAS-transgenes. Results In this study germ-line ablation caused by the maternal tudor[1] mutation was examined in a long-lived genetic background, and was found to increase life span in males but not in females, consistent with previous reports. Fitting the data to a Gompertz-Makeham model indicated that the maternal tudor[1] mutation increases the life span of male progeny by decreasing age-independent mortality. The Geneswitch system was used to screen through several UAS-type and EP-type P element mutations in genes that regulate sexual differentiation, to determine if additional sex-specific effects on life span would be obtained. Conditional over-expression of transformer female isoform (traF during development produced male adults with inhibited sexual differentiation, however this caused no significant change in life span. Over-expression of doublesex female isoform (dsxF during development was lethal to males, and produced a limited

  13. Live-Load Testing Application Using a Wireless Sensor System and Finite-Element Model Analysis of an Integral Abutment Concrete Girder Bridge

    Directory of Open Access Journals (Sweden)

    Robert W. Fausett

    2014-01-01

    Full Text Available As part of an investigation on the performance of integral abutment bridges, a single-span, integral abutment, prestressed concrete girder bridge near Perry, Utah was instrumented for live-load testing. The live-load test included driving trucks at 2.24 m/s (5 mph along predetermined load paths and measuring the corresponding strain and deflection. The measured data was used to validate a finite-element model (FEM of the bridge. The model showed that the integral abutments were behaving as 94% of a fixed-fixed support. Live-load distribution factors were obtained using this validated model and compared to those calculated in accordance to recommended procedures provided in the AASHTO LRFD Bridge Design Specifications (2010. The results indicated that if the bridge was considered simply supported, the AASHTO LRFD Specification distribution factors were conservative (in comparison to the FEM results. These conservative distribution factors, along with the initial simply supported design assumption resulted in a very conservative bridge design. In addition, a parametric study was conducted by modifying various bridge properties of the validated bridge model, one at a time, in order to investigate the influence that individual changes in span length, deck thickness, edge distance, skew, and fixity had on live-load distribution. The results showed that the bridge properties with the largest influence on bridge live-load distribution were fixity, skew, and changes in edge distance.

  14. Design of Cable-Stayed Bridge of Caofeidian Industry Zone Bridge No.1%曹妃甸工业区1号桥斜拉桥设计

    Institute of Scientific and Technical Information of China (English)

    陈亮; 卢永成; 周伟翔; 邵长宇

    2011-01-01

    The Caofeidian Industry Zone Bridge No. 1 is composed of navigable span bridge, non-navigable span bridges and approach bridges and is located in the cold and strong earthquake region in the northern part of China. A summarized account of the design of the navigable span bridge of the bridge is presented herewith. In accordance with the construction conditions and landscape requirements, the navigable span bridge is designed as a single pylon and single cable plane cable-stayed bridge with span arrangement 2 X 138 m, the pylon is the column pylon in shape of boat sail. The anchorage zone in the pylon is the steel anchor box exposed outside the pylon. The main girder is the steel and concrete composite girder having three cells and a single box. The stay cables are made up of φ7 mm galvanized parallel steel wires and the foundation of the pylon pier is the group pile foundation. The research of seismic resistance of the bridge show that for a major single pylon cable-stayed bridge located in the strong earthquake region, the rigid fixity system of pylon, girder and pier should be possibly avoided in order to reduce seismic response of the bridge structure.%曹妃甸工业区1号桥位于北方寒冷强震区,由通航孔桥、非通航孔桥及引桥组成,综述该桥通航孔桥设计.根据建设条件及景观要求,通航孔桥为跨径2×138 m独塔单索面斜拉桥;桥塔为独柱形,造型为船帆式;索塔锚固区采用外露式钢锚箱方案;主梁采用单箱三室钢-混凝土箱形结合梁;斜拉索采用φ7 mm镀锌平行钢丝;桥塔墩采用群桩基础.抗震性能研究表明,强震区大型独塔斜拉桥应尽量避免采用塔、梁、墩固结体系,以减小桥梁结构的地震响应.

  15. Development of the perceptual span in reading: A longitudinal study.

    Science.gov (United States)

    Sperlich, Anja; Meixner, Johannes; Laubrock, Jochen

    2016-06-01

    The perceptual span is a standard measure of parafoveal processing, which is considered highly important for efficient reading. Is the perceptual span a stable indicator of reading performance? What drives its development? Do initially slower and faster readers converge or diverge over development? Here we present the first longitudinal data on the development of the perceptual span in elementary school children. Using the moving window technique, eye movements of 127 German children in three age groups (Grades 1, 2, and 3 in Year 1) were recorded at two time points (T1 and T2) 1 year apart. Introducing a new measure of the perceptual span, nonlinear mixed-effects modeling was used to separate window size effects from asymptotic reading performance. Cross-sectional differences were well replicated longitudinally. Asymptotic reading rate increased monotonously with grade, but in a decelerating fashion. A significant change in the perceptual span was observed only between Grades 2 and 3. Together with results from a cross-lagged panel model, this suggests that the perceptual span increases as a consequence of relatively well-established word reading. Stabilities of observed and predicted reading rates were high after Grade 1, whereas the perceptual span was only moderately stable for all grades. Comparing faster and slower readers as assessed at T1, in general, a pattern of stable between-group differences emerged rather than a compensatory pattern; second and third graders even showed a Matthew effect in reading rate and the perceptual span, respectively.

  16. Developmental Regulation across the Life Span: Toward a New Synthesis

    Science.gov (United States)

    Haase, Claudia M.; Heckhausen, Jutta; Wrosch, Carsten

    2013-01-01

    How can individuals regulate their own development to live happy, healthy, and productive lives? Major theories of developmental regulation across the life span have been proposed (e.g., dual-process model of assimilation and accommodation; motivational theory of life-span development; model of selection, optimization, and compensation), but they…

  17. Measuring Boundary-Spanning Behaviors in Community Engagement

    Science.gov (United States)

    Sandmann, Lorilee R.; Jordan, Jenny W.; Mull, Casey D.; Valentine, Thomas

    2014-01-01

    Community engagement professionals and partners serve as, work with, study, and build the capacity of boundary spanners. To augment knowledge about these functions, the Weerts-Sandmann Boundary Spanning Conceptual Framework (2010) has been operationalized through a survey instrument to examine community engagement boundary-spanning behaviors by…

  18. Community Engagement and Boundary-Spanning Roles at Research Universities

    Science.gov (United States)

    Weerts, David J.; Sandmann, Lorilee R.

    2010-01-01

    Over the past decade, community engagement has emerged as an important priority among many colleges and universities. This study employs a multi-case study design to examine boundary spanning practices of research universities that have adopted a community engagement agenda. A model is advanced to conceptualize spanning behaviors and to inform…

  19. The Effect of Orthographic Neighborhood in the Reading Span Task

    Science.gov (United States)

    Robert, Christelle; Postal, Virginie; Mathey, Stéphanie

    2015-01-01

    This study aimed at examining whether and to what extent orthographic neighborhood of words influences performance in a working memory span task. Twenty-five participants performed a reading span task in which final words to be memorized had either no higher frequency orthographic neighbor or at least one. In both neighborhood conditions, each…

  20. Minimum Cost Spanning Tree Games and Population Monotonic Allocation Schemes

    NARCIS (Netherlands)

    Norde, H.W.; Moretti, S.; Tijs, S.H.

    2001-01-01

    In this paper we present the Subtraction Algorithm that computes for every classical minimum cost spanning tree game a population monotonic allocation scheme.As a basis for this algorithm serves a decomposition theorem that shows that every minimum cost spanning tree game can be written as nonnegati

  1. Facilitating conditions for boundary-spanning behaviour in governance networks

    NARCIS (Netherlands)

    I.F. van Meerkerk (Ingmar); J. Edelenbos (Jurian)

    2017-01-01

    textabstractThis article examines the impact of two facilitating conditions for boundary-spanning behaviour in urban governance networks. While research on boundary spanning is growing, there is little attention for antecedents. Combining governance network literature on project management and

  2. Facilitating conditions for boundary-spanning behavior in governance networks

    NARCIS (Netherlands)

    I.F. van Meerkerk (Ingmar); J. Edelenbos (Jurian)

    2017-01-01

    textabstractThis article examines the impact of two facilitating conditions for boundary-spanning behaviour in urban governance networks. While research on boundary spanning is growing, there is little attention for antecedents. Combining governance network literature on project management and

  3. Explaining operational modal analysis with data from an arch bridge

    Science.gov (United States)

    Magalhães, Filipe; Cunha, Álvaro

    2011-07-01

    This tutorial paper aims to introduce the topic of operational modal analysis to non-specialists on the subject. First of all, it is stressed the relevance of this experimental technique particularly in the assessment of important civil infrastructure. Then, after a synthesis of required theoretical background, three of the most powerful algorithms for output-only modal identification are presented. The several steps of these identification procedures are illustrated with the processing of data collected on a concrete arch bridge with a span of 280 m. As the use of operational modal analysis in the context of structural health monitoring is a subject under active research, this theme is also introduced and briefly exemplified with data continuously recorded at the same bridge.

  4. Stress and noises of steel box girders in Sutong Bridge

    Institute of Scientific and Technical Information of China (English)

    Xue Tao; Chen Zhijian; Dong Xuewu

    2008-01-01

    Sutong Bridge is a cable-stayed bridge with a main span of 1 088 m.370 high-precision stress monitoring measured data show that in the process of hoisting the steel box girders,the stress of the main girders is in the fluctuant and complex state and many meteorological factors,such as sunshine radiation,temperature and wind,have important influence on the change of stress of the steel box girders.According to the real-time weather data,the stress data after the process of wavelet denoising from representative measuring points in different weather conditions is picked to estab-lish the stress response brought by meteorological factors with Layered Separation method,thereby basically eliminating the influence of meteorological factors on the stress of main girders,so that accurate and reliable stress data can be got for steel box girders adjustment and cable-tensioned construction control.

  5. An innovative steel-concrete joint for integral abutment bridges

    Directory of Open Access Journals (Sweden)

    Bruno Briseghella

    2015-08-01

    Full Text Available Integral abutment bridges are becoming rather common, due to the durability problems of bearings and expansion joints. At the same time, among short- and medium-span bridges, multi-beam steel-concrete composite deck with hot-rolled girder is an economical and interesting alternative to traditional pre-stressed concrete solutions. The two concepts can be linked together to design integral steel-concrete composite bridges with the benefits of two typologies. The most critical aspect for these bridges is usually the joints between deck and piers or abutments. In this paper, an innovative beam-to-pier joint is proposed and a theoretical and experimental study is introduced and discussed. The analyzed connection is aimed at combining general ease of construction with a highly simplified assembly procedure and a good transmission of hogging and sagging moment at the supports in continuous beams. For this purpose, the traditional shear studs, used at the interface between steel beam and upper concrete slab, are also used at the ends of steel profiles welded horizontally to the end plates. To better understand the behaviour of this kind of joints and the roles played by different components, three large-scale specimens were tested and an FE model was implemented. The theoretical and experimental results confirmed the potential of the proposed connection for practical applications and indicated the way to improve its structural behaviour.

  6. Power, Governance and Boundary Spanning Leadership in Public Sector Organisations

    DEFF Research Database (Denmark)

    Elmholdt, Claus Westergård; Fogsgaard, Morten

    2015-01-01

    in public sector organizations. This research project has, among other things, highlighted the ways in which boundary spanning leadership can be related to establishing a shared pool of actions, knowledge, communication, trust and identity in the organization. Furthermore, the research project stresses......The phenomenon of power and boundary spanning leadership in public sector organizations is the topic for the present workshop. In this workshop we present a practice perspective (Corradi, Gherardi and Verzelloni 2010) on the management of power and boundary spanning leadership. We will focus...... on the practice that evolves on the boundaries that span occupational groups, departments and organizations. The workshop takes it’s starting point in an interdisciplinary Scandinavian research project which deals with the question of how power processes can promote, or hinder, boundary spanning leadership...

  7. Fuzzy α-minimum spanning tree problem: definition and solutions

    Science.gov (United States)

    Zhou, Jian; Chen, Lu; Wang, Ke; Yang, Fan

    2016-04-01

    In this paper, the minimum spanning tree problem is investigated on the graph with fuzzy edge weights. The notion of fuzzy ? -minimum spanning tree is presented based on the credibility measure, and then the solutions of the fuzzy ? -minimum spanning tree problem are discussed under different assumptions. First, we respectively, assume that all the edge weights are triangular fuzzy numbers and trapezoidal fuzzy numbers and prove that the fuzzy ? -minimum spanning tree problem can be transformed to a classical problem on a crisp graph in these two cases, which can be solved by classical algorithms such as the Kruskal algorithm and the Prim algorithm in polynomial time. Subsequently, as for the case that the edge weights are general fuzzy numbers, a fuzzy simulation-based genetic algorithm using Prüfer number representation is designed for solving the fuzzy ? -minimum spanning tree problem. Some numerical examples are also provided for illustrating the effectiveness of the proposed solutions.

  8. Effective way to reconstruct arch bridges using concrete walls and transverse strands

    Science.gov (United States)

    Klusáček, Ladislav; Pěkník, Robin; Nečas, Radim

    2017-09-01

    There are more than 500 masonry arch bridges in the Czech Road system and about 2500 in the Czech Railway system. Many of them are cracked in the longitudinal (span) direction. The barrel vaults are separated by the cracks into partial masonry arches without load bearing connection in transverse direction. These constructions are about 150 years old and they are also too narrow for the current road system. This paper presents a strengthening method for masonry arch bridges using transverse post-tensioning. This method is very useful not only for strengthening in the transverse direction, but widening of masonry arches can be taken as secondary effect especially in case of road bridges. Several bridges were successfully repaired with the use of this system which seems to be effective and reliable.

  9. Investigations concerning seismic response control of self-anchored suspension bridge with MR dampers

    Institute of Scientific and Technical Information of China (English)

    Menggang YANG; Zhengqing CHEN; Jianhua HU

    2008-01-01

    To mitigate the seismic response of selfanchored suspension bridges, equations of motion governing the coupled system of bridge- magneto-rheological (MR) dampers subject to seismic excitation are formulated by employing the phenomenological model of MR dampers. A corresponding computer program is developed and employed for studying the seismic response control of a self-anchored suspension bridge with a main span of 350 m. The effect of variable current and number of dampers on seismic response control is investigated. The numerical results indicate the longitudinal displacement of the tower top and bridge girder decrease with the increase in input current and number of MR dampers attached longitudinally at the tower-girder connections, and the internal forces of the tower are effectively attenuated as well. It appears that small electronic current (0.5 A in this study) may sufficiently attenuate the seismic responses for practical engineering applications.

  10. Recent research and applications of GPS based technology for bridge health monitoring

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Today,long-span bridges are being designed to be more flexible and to resist extensive impacts from changes in temperature,severe wind gusts and earthquake tremors. Structural responses (especially displacement) of bridge structures are becoming increasingly important for the finite element (FE) modal updating,structural response prediction and safety evaluation. Methods of global displacement sensing were developed for these needs. This paper presents an overview of current research and development activities in the field of bridge health monitoring using the global positioning system (GPS). The GPS monitoring technology and its accuracy assessment method are also briefly described. Finally,existing problems and promising research efforts in the GPS based bridge health monitoring are discussed.

  11. Multiplexed Bragg grating optical fiber sensors for damage evaluation in highway bridges

    Science.gov (United States)

    Idriss, R. L.; Kodindouma, M. B.; Kersey, A. D.; Davis, M. A.

    1998-04-01

    A multiplexed Bragg grating optical fiber monitoring system is designed and integrated at the construction stage in an experimental full scale laboratory bridge. The test bridge is a 40 ft span non-composite steel girder concrete deck bridge. The network of sensors is used to measure the strain throughout the bridge, with sensors bonded to the tension steel in the slab and attached to the bottom flange of the girders. Resistive strain gages and Bragg grating sensors are placed side by side to compare results. The strain data are obtained for the pristine structure, then damage is introduced at midspan for an exterior girder. Several levels of damage in the form of cuts in one of the girders are imposed with the final cut resulting in a half depth fracture of the girder. The load path in the structure is obtained using the built in sensor system.

  12. Probabilistic Fatigue Life Prediction of Bridge Cables Based on Multiscaling and Mesoscopic Fracture Mechanics

    Directory of Open Access Journals (Sweden)

    Zhongxiang Liu

    2016-04-01

    Full Text Available Fatigue fracture of bridge stay-cables is usually a multiscale process as the crack grows from micro-scale to macro-scale. Such a process, however, is highly uncertain. In order to make a rational prediction of the residual life of bridge cables, a probabilistic fatigue approach is proposed, based on a comprehensive vehicle load model, finite element analysis and multiscaling and mesoscopic fracture mechanics. Uncertainties in both material properties and external loads are considered. The proposed method is demonstrated through the fatigue life prediction of cables of the Runyang Cable-Stayed Bridge in China, and it is found that cables along the bridge spans may have significantly different fatigue lives, and due to the variability, some of them may have shorter lives than those as expected from the design.

  13. Towards Maximum Spanning Tree Model in Web 3.0 Design and Development for Students using Discriminant Analysis

    CERN Document Server

    Padma, S

    2012-01-01

    Web 3.0 is an evolving extension of the web 2.0 scenario. The perceptions regarding web 3.0 is different from person to person . Web 3.0 Architecture supports ubiquitous connectivity, network computing, open identity, intelligent web, distributed databases and intelligent applications. Some of the technologies which lead to the design and development of web 3.0 applications are Artificial intelligence, Automated reasoning, Cognitive architecture, Semantic web . An attempt is made to capture the requirements of Students inline with web 3.0 so as to bridge the gap between the design and development of web 3.0 applications and requirements among Students. Maximum Spanning Tree modeling of the requirements facilitate the identification of key areas and key attributes in the design and development of software products for Students in Web 3.0 using Discriminant analysis. Keywords : Web 3.0, Discriminant analysis, Design and Development, Model, Maximum Spanning Tree 1.

  14. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2004-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  15. Fatigue tests on aluminium bridges

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Straalen, IJ.J. van

    2005-01-01

    Traffic bridges are subjected to variable loads and should therefore be checked on fatigue. Especially low weight materials, like aluminium, are sensitive to fatigue, because the variable load is a substantial part of the total load. This paper shows the structural design of an aluminium bridge load

  16. London Bridge Is Shaking Funny

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    Bridges generally don’t fall down without warning;they crack first. Searching for cracks is a tedious business,though, and bridge inspectors bave been known to miss them. Charles Farrar,a civil engineer at Los Alamos Na-

  17. Bilinear slack span calculation model. Slack span calculations for high-temperature cables; Bilineares Berechnungsmodell fuer Durchhangberechnungen. Durchhangberechnungen bei Hochtemperaturleitern

    Energy Technology Data Exchange (ETDEWEB)

    Scheel, Joerg; Dib, Ramzi [Fachhochschule Giessen-Friedberg, Friedberg (Germany); Sassmannshausen, Achim [DB Energie GmbH, Frankfurt (Main) (Germany). Arbeitsgebiet Bahnstromleitungen Energieerzeugungs- und Uebertragungssysteme; Riedl, Markus [Eon Netz GmbH, Bayreuth (Germany). Systemtechnik Leitungen

    2010-12-13

    Increasingly, high-temperature cables are used in high-voltage grids. Beyond a given temperature level, their slack span cannot be calculated accurately by conventional simple linear methods. The contribution investigates the behaviour of composite cables at high operating temperatures and its influence on the slack span and presents a more accurate, bilingual calculation method. (orig.)

  18. Detailed free span assessment for Mexilhao flow lines

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Antonio; Franco, Luciano; Eigbe, Uwa; BomfimSilva, Carlos [INTECSEA, Houston, TX (United States); Escudero, Carlos [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2009-07-01

    The subsea gas production system of Mexilhao Field SPS-35, Santos Basin, offshore Brazil, is composed basically of two rigid 12.75 inches production flow lines approximately 21 km long installed in a fairly rough seabed. During the basic design, the free span assessment was performed considering the maximum allowable free span length determined by the response model proposed by DNV-RP-F105. This approach resulted in a large number of predicted free span requiring corrections, leading to a higher capital cost for the project. In this sense, a detailed free span VIV fatigue assessment was proposed, considering multi-spans and multi-mode effects and also the post lay survey data. The assessment followed the DNV-RP-F105 recommendations for multi-spans and multi-mode effects, using Finite Element Analysis to determine the natural frequencies, mode shapes and corresponding stresses associated with the mode shapes. The assessment was performed in three stages, the first during the detailed design as part of the bottom roughness analysis using the expected residual pipelay tension. The second stage was performed after pipelay, considering the post-lay survey data, where the actual requirements for span correction were determined. Actual pipelay tension was used and seabed soil stiffness adjusted in the model to match the as-laid pipeline profile obtained from the survey data. The first and second stage assessments are seamlessly automated to speed up the evaluation process and allow for quick response in the field, which was important to keep the construction vessel time minimized. The third stage was performed once the corrections of the spans were made and the purpose was to confirm that the new pipeline configuration along the supported spans had sufficient fatigue life for the temporary and operational phases. For the assessment of all three stages, the probability of occurrence and directionality of the near bottom current was considered to improve prediction of the

  19. Linguistic Barriers and Bridges

    DEFF Research Database (Denmark)

    Thuesen, Frederik

    2016-01-01

    and intercultural communication, this article analyses interviews with 31 employees from two highly ethnically diverse Danish workplaces. The article shows how linguistic barriers such as different levels of majority language competence and their consequent misunderstandings breed mistrust and hostility, whilst......The influence of language on social capital in low-skill and ethnically diverse workplaces has thus far received very limited attention within the sociology of work. As the ethnically diverse workplace is an important social space for the construction of social relations bridging different social...... groups, the sociology of work needs to develop a better understanding of the way in which linguistic diversity influences the formation of social capital, i.e. resources such as the trust and reciprocity inherent in social relations in such workplaces. Drawing on theories about intergroup contact...

  20. Electrothermally Tunable Bridge Resonator

    KAUST Repository

    Hajjaj, Amal Z.

    2016-12-05

    This paper demonstrates experimentally, theoretically, and numerically a wide-range tunability of an in-plane clamped-clamped microbeam, bridge, and resonator compressed by a force due to electrothermal actuation. We demonstrate that a single resonator can be operated at a wide range of frequencies. The microbeam is actuated electrothermally, by passing a DC current through it. We show that when increasing the electrothermal voltage, the compressive stress inside the microbeam increases, which leads eventually to its buckling. Before buckling, the fundamental frequency decreases until it drops to very low values, almost to zero. After buckling, the fundamental frequency increases, which is shown to be as high as twice the original resonance frequency. Analytical results based on the Galerkin discretization of the Euler Bernoulli beam theory are generated and compared to the experimental data and to simulation results of a multi-physics finite-element model. A good agreement is found among all the results.