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Sample records for bridge deck reliability

  1. To the question of reliability and durability ballastless deck of bridge

    Directory of Open Access Journals (Sweden)

    V.V. Prystynskaya

    2012-12-01

    Full Text Available The principal causes of operational defects in bridge ballastless deck plates are considered in the article. The drawbacks of these plates construction that prevent from achieving a higher level of bridge framework reliability and durability have been analysed.

  2. 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...

  3. Steel plate reinforcement of orthotropic bridge decks

    NARCIS (Netherlands)

    Teixeira de Freitas, S.

    2012-01-01

    The PhD research is focused on the reinforcement of fatigue cracked orthotropic steel bridge decks (OBD) by adding a second steel plate to the existing deck. The main idea is to stiffen the existing deck plate, which will reduce the stresses at the fatigue sensitive details and extend the fatigue li

  4. 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...

  5. Renovation techniques for fatigue cracked orthotropic steel bridge decks

    NARCIS (Netherlands)

    de Jong, F.B.P.

    2007-01-01

    This dissertation presents the research into renovation techniques for orthotropic steel bridge decks. These techniques are needed to solve fatigue problems in the decks of these bridges, as several fatigue cracks have been detected in the deck structure of these bridges the last decade. A well-know

  6. Analysis of Biaxially Stressed Bridge Deck Plates

    DEFF Research Database (Denmark)

    Jönsson, Jeppe; Bondum, Tommi Højer

    2012-01-01

    The ultimate state analysis of bridge deck plates at the intersection zone between main girders and transverse beams is complicated by biaxial membrane stresses, which may be in compression or tension in either direction depending on the bridge configuration and the specific location. This paper...... presents a detailed investigation of the ultimate capacity of simply supported plates subjected to biaxial loads. The full interaction domain of combinations of compressive and tensile loads has been investigated including a large number of imperfections. It was found that non-standard imperfection modes...

  7. Crack growth prediction of deck plate-stiffener joints in orthotropic steel bridge decks

    NARCIS (Netherlands)

    Maljaars, J.; Gration, D.; Vonk, E.; Dooren, F. van

    2013-01-01

    Orthotropic deck structures are used in many steel bridges. Due to the typical detailing applied as around 1970, a significant number of deck structures constructed in that period suffer from fatigue damage. In many countries cracks have been detected, in particular in the weld between the deck plat

  8. Fatigue Performance of Bridge Deck Pavement Materials

    Institute of Scientific and Technical Information of China (English)

    WU Shaopeng; ZHANG Guang; HAN Jun; LIU Gang; ZHOU Jie

    2009-01-01

    Three beam samplesof bridge deck pavementwere prepared, with gradationtypes of AC-13, and AC-16 and combined AC-13+AC-16. Four-point bending test was adopted to investigate the fatigue performance of these beam samples. The experimental results indicate that the initial bending stiffness is related to the type of beam sample and testing temperature. Fatigue life of these samples decreases as the increase of the controlled strain level. The AC-13 beam sample exhibits better fatigue resistance and bigger limiting bending strain at the given strain level and temperature. Com-pared with single beam sample, the fatigue performance of combining beam sample is relatively poor.

  9. Detection of Subsurface Defects in Concrete Bridge Deck Joints

    Directory of Open Access Journals (Sweden)

    Wonchang Choi

    2011-01-01

    Full Text Available Problem statement: The integrity of deck joints in highway bridges plays a major role to determine overall performance of bridge system. As the bridge maintenance program, the defects in deck joints have historically been detected by conventional non-destructive testing and evaluation methods such as visual inspection, chain-dragging and by the detecting sounds under the traffic. Future bridge maintenance challenges will demand the development of techniques and procedures to detect and monitor such defects before they become apparent. Approach: Two non-destructive methods; namely Ground Penetration Radar (GPR and Seismic Properties Analyzer (SPA were employed to assess the integrity of deck joins installed in North Carolina bridges. Results: The results obtained with the GPR and SPA allows to quantify the subsurface defects in bridge deck joints. Conclusion: The practical application and limitations of each method are discussed in this study.

  10. Ground-penetrating radar evaluation of bridge decks

    Science.gov (United States)

    Roberts, Glenn E.

    1995-05-01

    Radar has emerged as a valuable non-destructive test method for evaluating the condition of New Hampshire bridge decks. It allows the inspector to 'see' the top surface of the portland cement concrete deck which is typically covered with asphalt pavement. Radar is also very 'customer friendly' in that it allows inspectors to evaluate the bridge decks without closing travel lanes or otherwise impeding traffic flow in any way. This paper discusses the inspection needs of the New Hampshire Department of Transportation which necessitated the use of radar, as well as a history of its selection, development, and incorporation into New Hampshire's bridge management system.

  11. 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...

  12. Experimental evaluation and field implementation of FRP bridge deck modules

    Directory of Open Access Journals (Sweden)

    Woraphot Prachasaree

    2008-07-01

    Full Text Available Construction of highway bridge decks using fiber reinforced polymer (FRP composite deck and superstructuremodules in lieu of concrete decks has proven to be feasible. However, FRP’s are not widely accepted yet despite theirbenefits such as non-corrosiveness, higher strength to weight ratio, and better fatigue resistance than conventional materials.Lack of wider usage of FRP material is mainly attributed to the absence of: 1 standardized test procedures, 2 designspecifications, and 3 construction procedures. The higher initial cost is also inhibiting bridge engineers in selecting FRPmodules as highway bridge super structural systems.Implementation of FRP composites technology for highway bridge decks leads to higher safety and lower life cyclecosts. Significant ongoing research and development of FRP deck modules as illustrated herein, has proven to enhancedeck module properties in developing FRP modules with enhanced structural performance.Prodeck 4 is one such multicellular deck that was recently developed, and extensively evaluated for static and fatigueloads, and its response results are presented herein. From rigorous testing, it was concluded that Prodeck 4 could resistAASHTO HS 25 loading with maximum stringer spacing of 48 inches. This led to construction of two bridges (one in Ohioand other in West Virginia using Prodeck 4 as decking.

  13. a finite element model for the analysis of bridge decks

    African Journals Online (AJOL)

    Dr Obe

    The analysis of bridge decks is at present effected using mostly the method of distribution coefficients. The method involves the use of coefficients obtained from charts for the approximate determination of ..... Professional and Technical Books, ...

  14. Investigation of Aerodynamic Interference of Double Deck Bridges

    Energy Technology Data Exchange (ETDEWEB)

    Sitek, M. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Bojanowski, C. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC); Lottes, S. A. [Argonne National Lab. (ANL), Argonne, IL (United States). Energy Systems Division. Transportation Research and Analysis Computing Center (TRACC)

    2016-05-01

    Construction of a twin bridge can be a cost effective and minimally disruptive way to increase capacity when an existing bridge is not near the end of its service life. With ever growing vehicular traffic, when demand approaches the capacity of many existing roads and bridges. Remodeling a structure with an insufficient number of lanes can be a good solution in case of smaller and less busy bridges. Closing down or reducing traffic on crossings of greater importance for the construction period, however, can result in major delays and revenue loss for commerce and transportation as well as increasing the traffic load on alternate route bridges. Multiple-deck bridges may be the answer to this issue. A parallel deck can be built next to the existing one, without reducing the flow. Additionally, a new bridge can be designed as a twin or multi-deck structure. Several such structures have been built throughout the United States, among them: - The New NY Bridge Project - the Tappan Zee Hudson River Crossing, - SR-182 Columbia River Bridge, - The Thaddeus Kosciusko Bridge (I-87), - The Allegheny River Bridge, Pennsylvania, which carries I76, - Fred Hartman Bridge, TX, see Figure 1.2. With a growing number of double deck bridges, additional, more detailed, studies on the interaction of such bridge pairs in windy conditions appears appropriate. Aerodynamic interference effects should be examined to assure the aerodynamic stability of both bridges. There are many studies on aerodynamic response of single deck bridges, but the literature on double-deck structures is not extensive. The experimental results from wind tunnels are still limited in number, as a parametric study is required, they can be very time consuming. Literature review shows that some investigation of the effects of gap-width and angle of wind incidence has been done. Most of the CFD computational studies that have been done were limited to 2D simulations. Therefore, it is desirable to investigate twin decks

  15. Behavior of FRP Link Slabs in Jointless Bridge Decks

    Directory of Open Access Journals (Sweden)

    Aziz Saber

    2012-01-01

    Full Text Available The paper investigated the use of fiberglass-reinforced plastic (FRP grid for reinforcement in link slabs for jointless bridge decks. The design concept of link slab was examined based on the ductility of the fiberglass-reinforced plastic grid to accommodate bridge deck deformations. The implementation of hybrid simulation assisted in combining the experimental results and the theoretical work. The numerical analyses and the experimental work investigated the behavior of the link slab and confirmed its feasibility. The results indicated that the technique would allow simultaneous achievement of structural need, lower flexural stiffness of the link slab approaching the behavior of a hinge, and sustainability need of the link slab. The outcome of the study supports the contention that jointless concrete bridge decks may be designed and constructed with fiberglass-reinforced plastic grid link slabs. This concept would also provide a solution to a number of deterioration problems associated with bridge deck joints and can be used during new construction of bridge decks. The federal highway administration provided funds to Louisiana Department of Transportation through the innovative bridge research and development program to implement the use of FRP grid as link slab.

  16. Multidisciplinary health monitoring of a steel bridge deck structure

    NARCIS (Netherlands)

    Pahlavan, P.L.; Pijpers, R.J.M.; Paulissen, J.H.; Hakkesteegt, H.C.; Jansen, T.H.

    2013-01-01

    Fatigue cracks in orthotropic bridge decks are an important cause for the necessary renovation of existing bridges. Parallel utilization of various technologies based on different physical sensing principles can potentially maximize the efficiency of structural health monitoring (SHM) systems for th

  17. 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...

  18. 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...

  19. 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.

  20. Structural Assessment of Externally Strengthened Bridge Deck Panels

    Science.gov (United States)

    Sim, Jongsung; Oh, Hongseob; Meyer, Christian

    2006-03-01

    Deteriorated concrete bridge decks are strengthened with external bonding technique using either steel plate or various FRPs to enhance the decreased load carrying capacity and serviceability. But the failure characteristics of bridge decks strengthened with various materials can be changed according to mechanical properties of strengthening materials or strengthening scheme as well as the strengthening amount. In this paper, strengthening effect of deck strengthened with carbon fiber sheets, glass fiber sheets or steel plates is compared. And the theoretical load carrying capacity are evaluated using yield line theory and punching shear model properly modified for the strengthened RC member. The panels strengthened with sheet type FRP materials failed more often in a ductile mode, indicating that the failure developed after the rebar yielded.

  1. Service Life and Maintenance Modelling of Reinforced Concrete Bridge Decks

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Recent research in the area of assessment and maintenance of reinforced concrete bridge decks is presented in this paper. Three definitions of service lifetime are introduced and the difficult problem of assessing the service life is discussed. A stochastic modelling of corrosion and corrosion...

  2. Cathodic protection of RC structures - Far more than bridge decks

    NARCIS (Netherlands)

    Nerland, O.C.; Polder, R.B.

    2002-01-01

    When the first trials with Cathodic Protection (CP) on reinforced concrete (RC) structures were carried out nearly 30 years ago the main aim was treating steel in bridge decks, suffering from chloride induced corrosion. Various types of anode systems (conductive asphalt, conductive mortars, carbon f

  3. Concrete bridge deck early problem detection and mitigation using robotics

    Science.gov (United States)

    Gucunski, Nenad; Yi, Jingang; Basily, Basily; Duong, Trung; Kim, Jinyoung; Balaguru, Perumalsamy; Parvardeh, Hooman; Maher, Ali; Najm, Husam

    2015-04-01

    More economical management of bridges can be achieved through early problem detection and mitigation. The paper describes development and implementation of two fully automated (robotic) systems for nondestructive evaluation (NDE) and minimally invasive rehabilitation of concrete bridge decks. The NDE system named RABIT was developed with the support from Federal Highway Administration (FHWA). It implements multiple NDE technologies, namely: electrical resistivity (ER), impact echo (IE), ground-penetrating radar (GPR), and ultrasonic surface waves (USW). In addition, the system utilizes advanced vision to substitute traditional visual inspection. The RABIT system collects data at significantly higher speeds than it is done using traditional NDE equipment. The associated platform for the enhanced interpretation of condition assessment in concrete bridge decks utilizes data integration, fusion, and deterioration and defect visualization. The interpretation and visualization platform specifically addresses data integration and fusion from the four NDE technologies. The data visualization platform facilitates an intuitive presentation of the main deterioration due to: corrosion, delamination, and concrete degradation, by integrating NDE survey results and high resolution deck surface imaging. The rehabilitation robotic system was developed with the support from National Institute of Standards and Technology-Technology Innovation Program (NIST-TIP). The system utilizes advanced robotics and novel materials to repair problems in concrete decks, primarily early stage delamination and internal cracking, using a minimally invasive approach. Since both systems use global positioning systems for navigation, some of the current efforts concentrate on their coordination for the most effective joint evaluation and rehabilitation.

  4. Fatigue crack identification and lifetime prediction for steel bridge deck structures

    NARCIS (Netherlands)

    Pahlavan, P.L.; Pijpers, R.J.M.; Hakkesteegt, H.C.; Jansen, T.H.; Peelen, W.H.A.

    2015-01-01

    Fatigue, as the governing degradation mechanism in steel bridge decks, can lead to non-inspectable cracks under the welded intersections of stiffeners to the deck plate. As a result, estimation of the remaining service life and optimization of the maintenance program of steel bridge decks become a g

  5. Impact echo data from bridge deck testing: Visualization and interpretation

    OpenAIRE

    Gucunski, N.; Slabaugh, G.G.; Wang, Z; Fang, T.; A. Maher

    2008-01-01

    Accurate assessment of the condition of bridges leads to their economic management. Ultrasonic seismic methods can be successfully used for this purpose through evaluation of changes in material characteristics and detection of the development of defects and zones of deterioration. The impact echo (IE) method is of special benefit in evaluation of corrosion-induced deck delamination, due to the method's nondestructive nature, speed of evaluation, and ability to detect delaminated zones at var...

  6. 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.

  7. Fatigue Reliability of Deck Structures Subjected to Correlated Crack Growth

    Institute of Scientific and Technical Information of China (English)

    G.Q. Feng; Y. Garbatov; C. Guedes Soares

    2013-01-01

    The objective of this work is to analyse fatigue reliability of deck structures subjected to correlated crack growth. The stress intensity factors of the correlated cracks are obtained by finite element analysis and based on which the geometry correction functions are derived. The Monte Carlo simulations are applied to predict the statistical descriptors of correlated cracks based on the Paris-Erdogan equation. A probabilistic model of crack growth as a function of time is used to analyse the fatigue reliability of deck structures accounting for the crack propagation correlation. A deck structure is modelled as a series system of stiffened panels, where a stiffened panel is regarded as a parallel system composed of plates and are longitudinal. It has been proven that the method developed here can be conveniently applied to perform the fatigue reliability assessment of structures subjected to correlated crack growth.

  8. Experimental study of aerodynamic interference effects on aerostatic coefficients of twin deck bridges

    Institute of Scientific and Technical Information of China (English)

    Zhiwen LIU; Zhengqing CHEN; Gao LIU; Xinpeng SHAO

    2009-01-01

    The aerodynamic interference effects on aero-static coefficients of twin deck bridges with large span were investigated in detail by means of wind tunnel test.The distances between the twin decks and wind attack angles were changed during the wind tunnel test to study the effects on aerodynamic interferences of aerostatic coefficients of twin decks. The research results have shown that the drag coefficients of the leeward deck are much smaller than that of a single leeward deck. The drag coefficients of a windward deck decrease slightly com-pared with that of a single deck. The lift and torque coefficients of windward and leeward decks are also affected slightly by the aerodynamic interference of twin decks. And the aerodynamic interference effects on lift and torque coefficients of twin decks can be neglected.

  9. Identification of Flutter Derivatives of Bridge Decks in Wind Tunnel Test by Stochastic Subspace Identification

    Directory of Open Access Journals (Sweden)

    T. Janesupasaeree

    2009-01-01

    Full Text Available Problem statement: Flutter derivatives are the essential parameters in the estimations of the flutter critical wind velocity and the responses of long-span cable supported bridges. These derivatives can be experimentally estimated from wind tunnel test results. Generally, wind tunnel test methods can be divided into free decay test and buffeting test. Compared with the free decay method, the buffeting test is simpler but its outputs appear random-like. This makes the flutter derivatives extraction from its outputs more difficult and then a more advanced system identification is required. Most of previous studies have used deterministic system identification techniques, in which buffeting forces and responses are considered as noises. These previous techniques were applicable only to the free decay method. They also confronted some difficulties in extracting flutter derivatives at high wind speeds and under turbulence flow cases where the buffeting responses dominate. Approach: In this study, the covariance-driven stochastic subspace identification technique (SSI-COV was presented to extract the flutter derivatives of bridge decks from the buffeting test results. An advantage of this method is that it considers the buffeting forces and responses as inputs rather than as noises. Numerical simulations and wind tunnel tests of a streamlined thin plate model conducted under smooth flow by the free decay and the buffeting tests were used to validate the applicability of the SSI-COV method. Then, wind tunnel tests of a two-edge girder blunt type of Industrial-Ring-Road Bridge deck (IRR were conducted under smooth and turbulence flow. Results: The identified flutter derivatives of the thin plate model by the SSI-COV technique agree well with those obtained theoretically. The results from the thin plate and the IRR Bridge deck validated the reliability and applicability of the SSI-COV technique to various experimental methods and conditions of wind flow

  10. 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.

  11. Stiffness and Strength of Fiber Reinforced Polymer Composite Bridge Deck Systems

    OpenAIRE

    2002-01-01

    This research investigates two principal characteristics that are of primary importance in Fiber Reinforced Polymer (FRP) bridge deck applications: STIFFNESS and STRENGTH. The research was undertaken by investigating the stiffness and strength characteristics of the multi-cellular FRP bridge deck systems consisting of pultruded FRP shapes. A systematic analysis procedure was developed for the stiffness analysis of multi-cellular FRP deck systems. This procedure uses the Method of Elasti...

  12. Linear and Non-linear Analysis of Fibre Reinforced Plastic Bridge Deck due to Vehicle Loads

    Science.gov (United States)

    Ray, Chaitali; Mandal, Bibekananda

    2015-06-01

    The present work deals with linear and nonlinear static analysis of fibre reinforced plastics composite bridge deck structures using the finite element method. The nonlinear static analysis has been carried out considering geometric nonlinearity. The analysis of bridge deck has been carried out under vehicle load as specified by IRC Class B wheel load classification. The formulation has been carried out using the finite element software package ANSYS 14.0 and the SHELL281 element is used to model the bridge deck. The bridge deck has also been modeled as a plate stiffened with closely spaced hollow box sections and a computer code is developed based on this formulation. The results obtained from the present formulation are compared with those available in the published literature. A parametric study on the stiffened bridge deck has also been carried out with varying dimensions of the stiffeners under vehicle loads.

  13. Reliability Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Middleton, C. R.

    This paper is partly based on research performed for the Highways Agency, London, UK under the project DPU/9/44 "Revision of Bridge Assessment Rules Based on Whole Life Performance: concrete bridges". It contains the 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. This paper is to some extend based on Thoft-Christensen et. al. [1996], Thoft-Christensen [1996] et. al. and Thoft-Christensen [1996]....

  14. 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.

  15. Influence of asphalt on fatigue crack monitoring in steel bridge decks using guided waves

    NARCIS (Netherlands)

    Pahlavan, P.L.; De Soares Silva e Melo Mota, M.; Blacquière, G.

    2016-01-01

    Asphalt materials generally exhibit temperature-dependent properties, which can influence the performance of fatigue crack inspection and monitoring systems for bridge deck structures. For a non-intrusive fatigue crack sizing methodology applied to steel decks using ultrasonic guided waves, the effe

  16. Influence of asphalt on fatigue crack monitoring in steel bridge decks using guided waves

    NARCIS (Netherlands)

    Pahlavan, P.L.; De Soares Silva e Melo Mota, M.; Blacquière, G.

    2016-01-01

    Asphalt materials generally exhibit temperature-dependent properties, which can influence the performance of fatigue crack inspection and monitoring systems for bridge deck structures. For a non-intrusive fatigue crack sizing methodology applied to steel decks using ultrasonic guided waves, the

  17. The interaction between the atmosphere and curing concrete bridge decks

    Science.gov (United States)

    Wojcik, Gary S.

    The long-term durability of concrete can be compromised by excessive concrete temperatures or temperature gradients and lack of moisture during the first few days after placement. Because the concrete binder components undergo temperature-dependent hydration reactions during this period, atmospheric and construction conditions influence the ultimate concrete quality. To understand this interaction, curing concrete bridge energy balances were estimated with meteorological techniques and calorimetry and model experiments were performed. The agreement of concrete hydration heat estimates from the energy balances, calorimetry experiments, and model simulations validates our methodology and results. In Chapter 2, we estimate from meteorological measurements and techniques the energy balances of four curing concrete bridge decks. One challenge is to determine fluxes from small surfaces (largest horizontal dimension exchange coefficients for small areas is developed. Chapter 3, we improve with calorimetry experiments a simple bimolecular heat generation expression for hydrating binder. We show that this expression, with a new parameterization accounting for retarder effects on hydration rates, simulates temperatures to within 2°C and 72 h heat generation (˜265 kJ kg-1) to within 10% of the observed. In Chapter 4, we present models developed with the field and laboratory work and show that the highest concrete temperatures occur at high initial concrete temperatures and air temperatures and humidities, and at low wind speeds and cloud cover fractions. Peak bridge concrete temperatures can exceed 60°C. Large concrete temperature gradients (˜2°C cm-1 ) occur at the concrete top surface and the support beam top. An application of the 1D model with input from a weather forecast model predicts concrete temperatures within 2°C of the observed and so is a suitable operational model.

  18. Field Application of Automated Power Arc Spraying System on Steel Bridge Deck

    Institute of Scientific and Technical Information of China (English)

    YI Chun-long; SUO Shuang-fu; SUN Zhi; PANG Xu-nan

    2004-01-01

    The effective corrosion protection coating and high productive coating equipment for steel bridge deck has been a challenge for bridge engineers for many years. An automated power arc spraying system was first designed and field applied to coating the deck of Wuhan Junshan Yangtze River Bridge in high efficiency. This steel bridge is a continuous orthotropic deck box girder cable-stayed bridge with 962 m in length and 38.8 m in width, whose width is the No. 1 in China. The whole orthotropic deck with over 35,000 m2surface area was arc-sprayed a protective coating of zinc on site, followed by a sealant and SMA paving material. The side face and bottom of box girders were arc-sprayed with aluminum in factory.Field application indicated that the newly designed automated power arc spraying system with fan nozzle and separate primary & secondary atomizing air had some advantages over the conventional arc spraying system, such as automated operation,big arc spray current, high spraying rate, big breadth of each coat, even and small atomized particles, high density and low porosity of sprayed coating, and high adhesive strength to the substrate.Working procedure of surface preparation and automated arc spraying on bridge deck were introduced, and the quality of sprayed coating is controlled strictly. Field tests proved that the application of this automated power arc spraying system is successful and suitable for coating the steel bridge deck.

  19. 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

  20. Analysis, prediction, and case studies of early-age cracking in bridge decks

    Science.gov (United States)

    ElSafty, Adel; Graeff, Matthew K.; El-Gharib, Georges; Abdel-Mohti, Ahmed; Mike Jackson, N.

    2016-06-01

    Early-age cracking can adversely affect strength, serviceability, and durability of concrete bridge decks. Early age is defined as the period after final setting, during which concrete properties change rapidly. Many factors can cause early-age bridge deck cracking including temperature change, hydration, plastic shrinkage, autogenous shrinkage, and drying shrinkage. The cracking may also increase the effect of freeze and thaw cycles and may lead to corrosion of reinforcement. This research paper presents an analysis of causes and factors affecting early-age cracking. It also provides a tool developed to predict the likelihood and initiation of early-age cracking of concrete bridge decks. Understanding the concrete properties is essential so that the developed tool can accurately model the mechanisms contributing to the cracking of concrete bridge decks. The user interface of the implemented computer Excel program enables the user to input the properties of the concrete being monitored. The research study and the developed spreadsheet were used to comprehensively investigate the issue of concrete deck cracking. The spreadsheet is designed to be a user-friendly calculation tool for concrete mixture proportioning, temperature prediction, thermal analysis, and tensile cracking prediction. The study also provides review and makes recommendations on the deck cracking based mainly on the Florida Department of Transportation specifications and Structures Design Guidelines, and Bridge Design Manuals of other states. The results were also compared with that of other commercially available software programs that predict early-age cracking in concrete slabs, concrete pavement, and reinforced concrete bridge decks. The outcome of this study can identify a set of recommendations to limit the deck cracking problem and maintain a longer service life of bridges.

  1. 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.

  2. Towards Sensor-Based Health Monitoring Systems for Bridge Decks: A Full-Depth Precast Deck Panels Case Study

    Directory of Open Access Journals (Sweden)

    Osama Y. Abudayyeh

    2010-01-01

    Full Text Available Traffic and variable loading conditions greatly influence the performance, durability, and safety of a bridge structure throughout its service life. Continuous monitoring can provide the basis for determining the deterioration rate and for estimating the remaining service life, thus assisting in making important decisions regarding bridge maintenance. This paper presents the design and implementation of a health monitoring system for condition assessment of full-depth precast concrete bridge deck, which was developed for the Parkview Bridge in Kalamazoo, Michigan. This system is composed of a remotely accessible on-site data acquisition system and a sensor network of vibrating wire strain gauges to monitor strain and temperature over given time increments. The system relies on the sensor network embedded in the bridge deck to gather static performance data under different loading conditions to provide condition assessment by collecting, storing, analyzing, and reporting relevant performance data over time. The paper presents a practical case study that mainly focuses on describing the initial steps in the development of the sensor network system, namely, the design (system architecture and data structures and construction along with examples of how the data is acquired, organized, presented, and analyzed, keeping in mind that the bridge is still early in its life-cycle and has not yet experienced any structural problems.

  3. 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

  4. 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.

  5. Using artificial neural networks in the design of orthotropic bridge decks

    Directory of Open Access Journals (Sweden)

    Ahmed Shamel Fahmy

    2016-12-01

    Full Text Available For orthotropic bridge decks a lot of progress has been made in the development of codes to aid in the design process, in addition to software tools for numerical analysis and design. However, professional software tools will not aid the designer in choosing a preliminary economic layout at the conceptual design stage. Designers would go through iterative, lengthy and expensive procedures to reach the best configuration. The present research provides a methodology to investigate the contingency of using artificial neural networks for conceptual design of orthotropic steel-deck bridge. A neural network model was trained with different combinations of dimensions, and eight types of safety checks were performed on all of them. The resulting network can predict whether the deck is safe or not. It is found that this approach for the selection of orthotropic deck dimensions is a better and cost-effective option compared with international codes or expert opinion.

  6. Rapid multichannel impact-echo scanning of concrete bridge decks from a continuously moving platform

    Science.gov (United States)

    Mazzeo, Brian A.; Larsen, Jacob; McElderry, Joseph; Guthrie, W. Spencer

    2017-02-01

    Impact-echo testing is a non-destructive evaluation technique for determining the presence of defects in reinforced concrete bridge decks based on the acoustic response of the bridge deck when struck by an impactor. In this work, we build on our prior research with a single-channel impactor to demonstrate a seven-channel impact-echo scanning system with independent control of the impactors. This system is towed by a vehicle and integrated with distance measurement for registering the locations of the impacts along a bridge deck. The entire impact and recording system is computer-controlled. Because of a winch system and hinged frame construction of the apparatus, setup, measurement, and take-down of the apparatus can be achieved in a matter of minutes. Signal processing of the impact responses is performed on site and can produce a map of delaminations immediately after data acquisition. This map can then be used to guide other testing and/or can be referenced with the results of other testing techniques to facilitate comprehensive condition assessments of concrete bridge decks. This work demonstrates how impact-echo testing can be performed in a manner that makes complete bridge deck scanning for delaminations rapid and practical.

  7. Stiffness and strength of fiber reinforced polymer composite bridge deck systems

    Science.gov (United States)

    Zhou, Aixi

    This research investigates two principal characteristics that are of primary importance in Fiber Reinforced Polymer (FRP) bridge deck applications: STIFFNESS and STRENGTH. The research was undertaken by investigating the stiffness and strength characteristics of the multi-cellular FRP bridge deck systems consisting of pultruded FRP shapes. A systematic analysis procedure was developed for the stiffness analysis of multi-cellular FRP deck systems. This procedure uses the Method of Elastic Equivalence to model the cellular deck as an equivalent orthotropic plate. The procedure provides a practical method to predict the equivalent orthotropic plate properties of cellular FRP decks. Analytical solutions for the bending analysis of single span decks were developed using classical laminated plate theory. The analysis procedures can be extended to analyze continuous FRP decks. It can also be further developed using higher order plate theories. Several failure modes of the cellular FRP deck systems were recorded and analyzed through laboratory and field tests and Finite Element Analysis (FEA). Two schemes of loading patches were used in the laboratory test: a steel patch made according to the ASSHTO's bridge testing specifications; and a tire patch made from a real truck tire reinforced with silicon rubber. The tire patch was specially designed to simulate service loading conditions by modifying real contact loading from a tire. Our research shows that the effects of the stiffness and contact conditions of loading patches are significant in the stiffness and strength testing of FRP decks. Due to the localization of load, a simulated tire patch yields larger deflection than the steel patch under the same loading level. The tire patch produces significantly different failure compared to the steel patch: a local bending mode with less damage for the tire patch; and a local punching-shear mode for the steel patch. A deck failure function method is proposed for predicting the

  8. First application of second-generation steel-free deck slabs for bridge rehabilitation

    Science.gov (United States)

    Eden, Ruth; Klowak, Chad; Mufti, Aftab A.; Tadros, Gamil; Bakht, Baidar; Loewen, Eric

    2004-07-01

    The arching action in concrete deck slabs for girder bridges is utilized fully in steel-free deck slabs. These concrete slabs, requiring no tensile reinforcement, are confined longitudinally by making them composite with the girders, and transversely by external steel straps connecting the top flanges of external girders. Between 1995 and 1999, five steel-free deck slabs without any tensile reinforcement were cast on Canadian bridges. All these slabs developed fairly wide full-depth cracks roughly midway between the girders. While extensive fatigue testing done in the past three years has confirmed that the presence of even wide cracks does not pose any danger to the safety of the structures, wide cracks are generally not acceptable to bridge engineers. The developers of the steel-free deck slabs have now conceded that these slabs should be reinforced with a crack-control mesh of nominal glass fibre reinforced polymer (GFRP) bars. Steel-free deck slabs with crack-control meshes are being referred as the second generation slabs. With the help of testing on full-scale models, it has been found that deck slabs with GFRP bars have the best fatigue resistance and those with steel bars the worst.

  9. Bridge deck repair and protective systems: latex modified concrete topping. Interim report

    Energy Technology Data Exchange (ETDEWEB)

    Swanson, H.N.

    1984-07-01

    Measures to reduce or eliminate bridge deck deterioration by the use of various protective systems have been the subject of a series of reports begun in 1976. This report presents current observations of latex-modified deck-topping concrete protective systems. Latex-modified concrete topping has not provided long-term protection for the ten structures under evaluation in Colorado. Cost comparisons are made between repair with latex-modified concrete and deck replacement. Over a 40-year period, replacement costs are slightly less than rehabilitation costs. Greater control of the curing of deck-topping materials may reduce shrinkage cracking. Nightime paving, cooler calmer weather and higher humidity would increase the probability of success on latex-modified concrete to rehabilitation projects. Asphalt membrane and asphalt overlay are also suggested to increase the probability of success.

  10. Demonstration and Validation of a Lightweight Composite Bridge Deck Technology as an Alternative to Reinforced Concrete

    Science.gov (United States)

    2016-08-01

    78 Figure 103. Extensive missing grout revealed after steel strips removed. .......................... 79 Figure 104. Grout leaking through caulk...ERDC/CERL TR-16-16 79 Figure 103. Extensive missing grout revealed after steel strips removed. Figure 104. Grout leaking through caulk. ERDC...Abstract Cyclic loading and weathering of reinforced concrete bridge decks cause corrosion of reinforcement steel , which leads to cracking, potholes

  11. Research on construction technology for orthotropic steel deck pavement of Haihe River Chunyi Bridge

    Science.gov (United States)

    Xue, Y. C.; Qian, Z. D.; Zhang, M.

    2017-01-01

    In order to ensure the good service quality of orthotropic steel deck pavement of Haihe River Chunyi Bridge in Tianjin, and to reduce the occurrence of pavement diseases like lateral and longitudinal cracks, the key working procedures such as steel deck cleaning, anticorrosive coating, bonding layer spraying, seam cutting, epoxy asphalt concrete’s mixing, transportation, paving and compaction were studied. The study was based on the main features of epoxy asphalt concrete which is the pavement materials of Haihe River Chunyi Bridge, and combined with the basic characteristics and construction conditions of Haihe River Chunyi Bridge. Furthermore, some processing measures like controlling time and temperature, continuous paving with two pavers, lateral feeding, and improving the compaction method were proposed. The project example shows that the processing measures can effectively solve the technical difficulties in the construction of orthotropic steel deck pavement of Haihe River Chunyi Bridge, can greatly improve the construction speed and quality, and can provide reference for the same kinds of orthotropic steel deck pavement construction.

  12. Advanced numerical study of the response of orthotropic steel deck bridge with two membrane layers system

    NARCIS (Netherlands)

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

    2012-01-01

    In the Netherlands an asphaltic surfacing structure for orthotropic steel bridge decks mostly consists of two structural layers. The upper layer consists of Porous Asphalt (PA) because of reasons related to noise hindrance. For the lower layer a choice between Mastic Asphalt (MA) or Guss Asphalt (GA

  13. Moving dynamic loads caused by bridge deck joint unevenness - a case study

    CSIR Research Space (South Africa)

    Steyn, WJV

    2004-11-01

    Full Text Available This paper focus on the general guidelines regarding maximum unevenness from bridge deck joints for typical South African heavy vehicles, in order to minimize the generation of moving variable loads. In a recent investigation it was found that areas...

  14. Lifetime Reliability Assessment of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    A procedure for lifetime assesment of the reliability of short concrete slab bridges is presented in the paper. Corrosion of the reinforcement is the deterioration mechanism used for estimating the reliability profiles for such bridges. The importance of using sensitivity measures is stressed. Fi...

  15. Assessment of concrete bridge decks with alkali silica reactions

    DEFF Research Database (Denmark)

    Eriksen, Kirsten; Jansson, Jacob; Geiker, Mette Rica

    2008-01-01

    Based on investigations of concrete from an approximately 40 years old bridge a procedure to support the management of maintenance and repair of alkali silica damaged bridges is proposed. Combined petrography and accelerated expansion testing were undertaken on cores from the Bridge at Skovdiget......, Bagsværd, Denmark to provide information on the damage condition as well as the residual reactivity of the concrete. The Danish Road Directory’s guidelines for inspection and assessment of alkali silica damaged bridges will be briefly presented, and proposed modifications will be describe...

  16. 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.

  17. An investigation of the seismic behavior of a deck-type reinforced concrete arch bridge

    Science.gov (United States)

    Farahani, Emadoddin Majdabadi; Maalek, Shahrokh

    2017-07-01

    This paper attempts to explore potential benefits of form in a deck-type reinforced concrete (RC) arch bridge in connection with its overall seismic behavior and performance. Through a detailed three-dimensional finite element modeling and analysis of an actual existing deck-type RC arch bridge, some useful quantitative information have been derived that may serve for a better understanding of the seismic behavior of such arch bridges. A series of the nonlinear dynamic analyses has been carried out under the action of seven different time histories of ground motion scaled to the AASHTO 2012 response spectrum. The concept of demand to capacity ratios has been employed to provide an initial estimation of the seismic performance of the bridge members. As a consequence of the structural form, a particular type of irregularity is introduced due to variable heights of columns transferring the deck loads to the main arch. Hence, a particular attention has been paid to the internal force/moment distributions within the short, medium, and long columns as well as along the main arch. A study of the effects of the vertical component of ground motion has demonstrated the need for the inclusion of these effects in the analysis of such bridges.

  18. Research on the Anticorrosion Coating Under the Paved Layer for Highway Steel Box Bridge Deck

    Institute of Scientific and Technical Information of China (English)

    SHEN Cheng-jin; MING Tu-zhang; HU Guang-wei; OU Xue-mei; GEN Ou

    2006-01-01

    The corrosion of the anticorrosion coating and the defects of the asphalt concrete paved layer have been investigated on long-span steel box bridge decks. The anticorrosion coating lies in the middle of two entirely different materials: a highway steel box bridge deck and a paved layer, which is used as anticorrosion and waterproof coating for the steel bridge deck. For our study, electrochemical corrosion and pull strength experiments have been selected for the investigation of the corrosion properties of inorganic zinc rich coating, epoxy zinc rich coating and arc sprayed zinc coating. The adhesive strength between the coatings and the panel, and the effect of the coating corrosion on the shear properties of the paved layers including cast asphalt, thermal asphalt mortar, epoxy asphalt and modified asphalt concrete have been investigated. The results show that the adhesive strength between the coatings and the bridge panel is controlled by the method of pre-processing rust removal. Coating by sandblasting has stronger adhesive strength than coating by shot peening. The results also reveal that shear strength of the paved layer is affected by the corrosion product of zinc coating. The arc sprayed zinc coating has stronger shear strength than zinc rich coatings.

  19. Performance of streamlined bridge decks in relation to the aerodynamics of a flat plate

    DEFF Research Database (Denmark)

    Larose, Guy; Livesey, Flora M.

    1997-01-01

    The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied in this ...... in this paper showed buffeting responses similar to a flat plate with the exception of the multi-box girder which performed much better aerodynamically.......The aerodynamics of three modern bridge decks are compared to the aerodynamics of a 16:1 flat plate. The comparisons are made on the basis of the analytical evaluation of the performance of each cross-section to the buffeting action of the wind. In general, the closed-box girders studied...

  20. An Advanced Coupled Genetic Algorithm for Identifying Unknown Moving Loads on Bridge Decks

    Directory of Open Access Journals (Sweden)

    Sang-Youl Lee

    2014-01-01

    Full Text Available This study deals with an inverse method to identify moving loads on bridge decks using the finite element method (FEM and a coupled genetic algorithm (c-GA. We developed the inverse technique using a coupled genetic algorithm that can make global solution searches possible as opposed to classical gradient-based optimization techniques. The technique described in this paper allows us to not only detect the weight of moving vehicles but also find their moving velocities. To demonstrate the feasibility of the method, the algorithm is applied to a bridge deck model with beam elements. In addition, 1D and 3D finite element models are simulated to study the influence of measurement errors and model uncertainty between numerical and real structures. The results demonstrate the excellence of the method from the standpoints of computation efficiency and avoidance of premature convergence.

  1. Smart Pebble: wireless sensors for structural health monitoring of bridge decks

    Science.gov (United States)

    Watters, David G.; Jayaweera, Palitha; Bahr, Alfred J.; Huestis, David L.; Priyantha, Namal; Meline, Robert; Reis, Robert; Parks, Douglas

    2003-08-01

    SRI International is developing a wireless sensor for monitoring the level of chloride ingress into concrete bridge decks. We call this device a Smart Pebble since it has roughly the size and weight of a typical piece of the rock aggregate that is used in such structures. It is "smart" in that it contains a chloride sensor and a radio-frequency identification (RFID) chip that can be queried remotely both to identify it and to indicate chloride concentration levels. The Smart Pebble is also powered remotely, thus precluding the need for any lifetime-limiting batteries. It is designed to be inserted in the bridge deck either during the initial construction (or during refurbishment) or in a back-filled core hole. This paper will discuss the Smart Pebble design, operation, and status.

  2. Structural Performance of Light Weight Multicellular FRP Composite Bridge Deck Using Finite Element Analysis

    Institute of Scientific and Technical Information of China (English)

    Woraphot Prachasaree; Pongsak Sookmanee

    2012-01-01

    Fiber reinforced polymer (FRP) composite materials having advantages such as higher strength to weight than conventional engineering materials,non-corrosiveness and modularization,which should help engineers to obtain more efficient and cost effective structural materials and systems.Currently,FRP composites are becoming more popular in civil engineering applications.The objectives of this research are to study performance and behavior of light weight multi-cellular FRP composite bridge decks (both module and system levels) under various loading conditions through finite element modeling,and to validate analytical response of FRP composite bridge decks with data from laboratory evaluations.The relative deflection,equivalent flexural rigidity,failure load (mode) and load distribution factors (LDF) based on FE results have been compared with experimental data and discussed in detail.The finite element results showing good correlations with experimental data are presented in this work.

  3. 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.

  4. A Novel Method for Evaluating Fatigue Properties of Bonding Layers Used in Bridge Deck Pavement

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jie; WU Shaopeng; HAN Jun; LIU Gang; ZHANG Guang

    2009-01-01

    A new method was used to evaluate the fatigue properties of the bonding layer used in the bridge deck pavement. The shear fatigue test of three bonding layers was conducted on a dy-namic shear rheometer(DSR). The fatigue formulas were gained for these layers. The experimental results indicate that, at the same torque level or at the same frequency, neoprene latex asphalt bonding layer exhibits excellent fatigue performance when compared to other two bonding layers.

  5. Assessment of the Reliability of Concrete Bridges

    DEFF Research Database (Denmark)

    Middleton, C. R.; Thoft-Christensen, Palle

    a significant shift in emphasis for the highways authorities around the world away from the design of new structures over to maintaining the existing infrastructure. As a result, bridge owners are seeking improved ways of inspecting, assessing, maintaining and repairing their existing stock of bridges...... in the wake of ever increasing traffic loads and volumes, and an ageing population of bridges subject to various mechanisms of deterioration. The goal is to optimise the allocation of limited resources whilst maintaining their bridges in a safe and serviceable condition. Reliability analysis is one tool being...

  6. Study of concrete drilling for automated non-destructive evaluation and rehabilitation system for bridge decks

    Science.gov (United States)

    Trkov, Mitja; Liu, Fei; Yi, Jingang; Baruh, Haim

    2011-04-01

    Robotic drilling is the basic process for the non-destructive rehabilitation (NDR) system in the Automated Non-destructive Evaluation and Rehabilitation System (ANDERS) for bridge decks. In this paper, we present a study and testing of a concrete drilling process that is used for robotic drilling process for bridge decks repair. We first review the ANDERS and NDR design. Then we present the experimental setup for the drilling process study. A set of testing experiments are performed considering drilling process parameters such as drill bit size, drill rotating speed, drill thrust force and types of concrete composites. Based on the experiments and analysis, we identify and find that the optimal set of drilling process parameters for the ANDERS application is 1/4-inch bit size, drill rotational speed of 1500 rpm and thrust force around 35 lbs. We also demonstrate that the monitoring of drill feeding displacement and thrust force cannot be used to detect and identify the cracks in bridge decks.

  7. 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.

  8. Estimation of Bridge Reliability Distributions

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper it is shown how the so-called reliability distributions can be estimated using crude Monte Carlo simulation. The main purpose is to demonstrate the methodology. Therefor very exact data concerning reliability and deterioration are not needed. However, it is intended in the paper to ...

  9. Bridge deck repairs with polymer concrete patching materials

    Science.gov (United States)

    Edgecomb, W. C., Jr.

    1983-01-01

    The FHWA polymer concrete as formulated at Brookhaven National laboratory (BNL) was mixed, placed into spalls and finished on grade with steel trowels on more than a dozen bridges. This polymer concrete was a two-component system consisting of a liquid monomer component comprised of methyl methacrylate base, which contained a cross linking agent with promoters and an inhibitor, and a powder component which contained reactive polymers, blend of silica sands, initiator, and color pigments. These formed an impregnable material of approximately 8000 psi. Cure time for this project's cold weather formulation to obtain this strength was approximately 2 hours at 40 F.

  10. Comparison between major repair and replacement options for a bridge deck life cycle assessment: A case study

    Directory of Open Access Journals (Sweden)

    Abu Dabous Saleh

    2017-01-01

    Full Text Available Material production, manufacturing, transportation, usage, and end of lifeprocessing are usually the main contributors defining the life cycle assessment (LCA. Bridge infrastructure is important to the economy and the society. Over their life cycle, highway bridges experience several stressors that can significantly affect their structural performance and therefore require rehabilitation. This paper discusses the life cycle analysis of bridge rehabilitation decisions and demonstrates the analysis with a case study of a bridge located in Ontario, Canada. The LCA of the bridge deck is analyzed for two rehabilitation strategies: major repair and replacement. The study focuses on evaluating the different life cycle phases of the bridge deck by assessing their carbon dioxide emission, energy consumption and cost. Also, the paper presents the impact of the different elements within each phase to identify the most contributing elements. The LCA of the bridge deck is analyzed and estimated with the aid of CES EduPack 2016 software that includes a database of more than 4000 different materials and more than 200 manufacturing processes. Analysis of the case study shows that material phase causes significant life cycle impact. The study concluded that the deck replacement yields higher environmental impact and life cycle cost compared to repairing and strengthening the deck.

  11. 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.

  12. Hybrid reliability model for fatigue reliability analysis of steel bridges

    Institute of Scientific and Technical Information of China (English)

    曹珊珊; 雷俊卿

    2016-01-01

    A kind of hybrid reliability model is presented to solve the fatigue reliability problems of steel bridges. The cumulative damage model is one kind of the models used in fatigue reliability analysis. The parameter characteristics of the model can be described as probabilistic and interval. The two-stage hybrid reliability model is given with a theoretical foundation and a solving algorithm to solve the hybrid reliability problems. The theoretical foundation is established by the consistency relationships of interval reliability model and probability reliability model with normally distributed variables in theory. The solving process is combined with the definition of interval reliability index and the probabilistic algorithm. With the consideration of the parameter characteristics of theS−N curve, the cumulative damage model with hybrid variables is given based on the standards from different countries. Lastly, a case of steel structure in the Neville Island Bridge is analyzed to verify the applicability of the hybrid reliability model in fatigue reliability analysis based on the AASHTO.

  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. Light-weight aluminium bridges and bridge decks. An overview of recent applications

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Kluyver, D. de

    2008-01-01

    The last decades have shown a large increase in the application of aluminium alloys for light-weight bridges. For bridge construction, aluminium alloys have some specific advantages, but also some points of attention. This paper deals with some recent projects of aluminium bridges, and for these pro

  15. Light-weight aluminium bridges and bridge decks. An overview of recent applications

    NARCIS (Netherlands)

    Maljaars, J.; Soetens, F.; Kluyver, D. de

    2008-01-01

    The last decades have shown a large increase in the application of aluminium alloys for light-weight bridges. For bridge construction, aluminium alloys have some specific advantages, but also some points of attention. This paper deals with some recent projects of aluminium bridges, and for these

  16. Durability assessment of concrete bridge deck considering waterproof membrane and epoxy-coated reinforcement

    Directory of Open Access Journals (Sweden)

    Petr Konečný

    2016-03-01

    Full Text Available The effect of waterproof membrane and steel reinforcement protection on the concrete bridge deck is modeled. The attention is paid to the durability prediction related to steel reinforcement corrosion initiation based on the chloride penetration. Thus 2-D finite element chloride ingress model is applied. The transient finite element model serves to solve Fick's second diffusion law using the computer tool compatible with the Matlab environment. The model focuses on the transport of chloride ions through a reinforced concrete bridge deck with and without the effect of waterproof membrane and on an estimate of the concentration of chlorides at the reinforcement level or in places with damage to the epoxide coating of the reinforcement. The model allows the incorporation of damage to the waterproof insulation under the asphalt coating. The time to chloride induced onset of corrosion is predicted and results are compared. The effect of water proof membrane reinforcement protection strategy typical for Central Europe and epoxy-coating protection widely used in North-Western United States is evaluated.

  17. Vertical impedance measurements of concrete bridge deck cover condition without a direct electrical connection to the reinforcing steel

    Science.gov (United States)

    Mazzeo, Brian A.; Baxter, Jared; Barton, Jeffrey; Guthrie, W. Spencer

    2017-02-01

    Vertical impedance measurements provide significant quantitative information about the ability of concrete cover to slow the penetration of chloride ions that can corrode steel reinforcement in a bridge deck. The primary limitations preventing the widespread adoption of vertical impedance for assessment of concrete bridge decks are (1) the necessity to have a direct electrical connection to the embedded steel reinforcement and (2) the low speeds of data acquisition. This work presents solutions to both limitations. A method using a large-area electrode as a reference electrode for vertical impedance testing is validated using both simulations and measurements in the field.

  18. Detection of Through-Deck Type Fatigue Cracks in Steel Bridges by Self-Reference Lock-in Thermography

    Directory of Open Access Journals (Sweden)

    Tamakoshi T.

    2010-06-01

    Full Text Available A new remote nondestructive inspection technique, based on thermoelastic temperature measurement by infrared thermography, is developed for detection and evaluation of fatigue cracks propagating from welded joints in steel bridges. Fatigue cracks are detected from localized high thermoelastic temperature change at crack tips due to stress singularity under variable loading from traffics on the bridge. Selfreference lock-in data processing technique is developed for the improvement of signal/noise ratio in the crack detection process. The technique makes it possible to perform correlation processing without an external reference signal. It is very difficult to detect through-deck type fatigue cracks in steel decks by the conventional NDT technique, since they are not open to the inspection. In this paper, self-reference lock-in thermography is applied for detection of through-deck type fatigue cracks. Experiments are carried out to steel deck sample, which simulates an actual steel bridge, during crack propagation test. It is found that significant stress concentration zone can be observed near the crack front, which enabled us to detect through-deck type fatigue cracks and to estimate its size.

  19. The Impact of Traffic-Induced Bridge Vibration on Rapid Repairing High-Performance Concrete for Bridge Deck Pavement Repairs

    Directory of Open Access Journals (Sweden)

    Wei Wang

    2014-01-01

    Full Text Available Based on forced vibration tests for high-performance concrete (HPC, the influence of bridge vibration induced by traveling vehicle on compressive strength and durability of HPC has been studied. It is concluded that 1 d and 2 d compressive strength of HPC decreased significantly, and the maximum reduction rate is 9.1%, while 28 d compressive strength of HPC had a slight lower with a 3% maximal drop under the action of two simple harmonic vibrations with 2 Hz, 3 mm amplitude, and 4 Hz, 3 mm amplitude. Moreover, the vibration had a slight effect on the compressive strength of HPC when the simple harmonic vibration had 4 Hz and 1 mm amplitude; it is indicated that the amplitude exerts a more prominent influence on the earlier compressive strength with the comparison of the frequency. In addition, the impact of simple harmonic vibration on durability of HPC can be ignored; this shows the self-healing function of concrete resulting from later hydration reaction. Thus, the research achievements mentioned above can contribute to learning the laws by which bridge vibration affects the properties of concrete and provide technical support for the design and construction of the bridge deck pavement maintenance.

  20. Structural Aspects of Railway Truss Bridges Affecting Transverse Shear Forces in Steel-Concrete Composite Decks

    Science.gov (United States)

    Siekierski, Wojciech

    2015-03-01

    At the steel-concrete interface, the horizontal shear forces that are transverse to cross beams occur due to joint action of the steel-concrete composite deck and the truss girders. Numerical analysis showed that values of the forces are big in comparison to the longitudinal shear forces. In both cases extreme force values occur near side edges of a slab. The paper studies possibilities of reduction of these shear forces by structural alterations of the following: rigidity of a concrete slab, arrangement of a wind bracing, arrangement of concrete slab expansion joints. An existing railway truss bridge span has been analysed. Numerical analysis shows that it is possible to reduce the values of shear forces transverse to cross beams. It may reach 20% near the side edges of slabs and 23% in the centre of slab width.

  1. Structural Aspects of Railway Truss Bridges Affecting Transverse Shear Forces in Steel-Concrete Composite Decks

    Directory of Open Access Journals (Sweden)

    Siekierski Wojciech

    2015-03-01

    Full Text Available At the steel-concrete interface, the horizontal shear forces that are transverse to cross beams occur due to joint action of the steel-concrete composite deck and the truss girders. Numerical analysis showed that values of the forces are big in comparison to the longitudinal shear forces. In both cases extreme force values occur near side edges of a slab. The paper studies possibilities of reduction of these shear forces by structural alterations of the following: rigidity of a concrete slab, arrangement of a wind bracing, arrangement of concrete slab expansion joints. An existing railway truss bridge span has been analysed. Numerical analysis shows that it is possible to reduce the values of shear forces transverse to cross beams. It may reach 20% near the side edges of slabs and 23% in the centre of slab width.

  2. Early age performance of latex-modified concrete bridge deck overlays

    Science.gov (United States)

    Sujjavanich, Suvimol

    Environmental factors and physical properties of latex modified concrete (LMC) are hypothesized to contribute to early age cracking in bridge deck overlays. Cracking permits the ingress of moisture and aggressive solutions into the substrate and may contribute to other subsequent distresses. Understanding the material properties and mechanisms involved is necessary to minimize these distresses. This research consisted of a two part study: first, the development of LMC strength and fracture properties at ages ranging from 5 hours to 28 days was studied, and secondly, the effects of the environment on LMC distresses were modelled. Environmental conditions: temperature, solar energy, and wind speed were determined from weather records. A fracture mechanics based model, the Fictitious Crack Model (FCM), incorporating finite element analyses and superposition techniques was employed with material properties from the first part of study on LMC performance. Different bilinear strain softening diagrams were used to predict fracture performance at different ages. The predictions agreed well with the test data. The impacts of temperature differentials on crack development were studied. The shrinkage effect was also indirectly incorporated through the temperature analysis. The material properties study indicated significant changes in strength, deformability and fracture properties, particularly during the early age. The developments differ slightly from conventional concrete. Test results indicated a significant improvement in reducing and bridging microcracks, especially in the prepeak-load region. Fracture toughness and deformability increased significantly with time. Fracture energy varied from 2.3 to 133.1 N/m, depending on age, and to some degree, on notch depth ratio. In the second stage, the FCM provided a reasonable prediction for crack initiation and propagation when only temperature effects are of concern. Age, surface conditions and structural restraint strongly

  3. S PS 夹层板桥面系统的研究应用进展%Advance in Research and Application of Sandwich Plate System Bridge Decks

    Institute of Scientific and Technical Information of China (English)

    程斌; 汤维力

    2015-01-01

    The sandwich plate system (SPS) is a kind of the composite structure that is made up of the upper and lower steel plates and an intermediate polyurethane core and has vast vista of application to the bridge engineering (particularly to the bridge decks) .In this paper ,the advan‐tages of the SPS are described from aspects of the material properties ,structural characteristics and mechanical behavior ,followed by a detailed introduction to the application and research ad‐vance of the SPS in the newly precast and assembled bridge decks ,replacement of the degraded concrete bridge decks ,strengthening of the conventional orthotropic steel bridge decks as well as the newly built SPS orthotropic steel bridge decks .The results show that the SPS is particularly applicable to the plate (slab) type structures that are mainly subjected to bending and all existing SPS bridge decks have exhibited the reliable mechanical behavior .Besides ,the numerical model‐ing methods for the SPS are also discussed and the future researches on the bond‐slip characteris‐tics of the interfaces ,standard structural details and general design approaches of the SPS are suggested .%夹层板系统(Sandwich Plate System ,SPS)是由上、下2层钢板和中间1层聚氨酯芯体组成的一种复合结构,在桥梁工程(尤其是桥面板工程)中具有广阔的应用前景。从材料性能、构造特点和受力特性角度阐述了SPS夹层板的优越性,并重点介绍了SPS夹层板在新建预制拼装桥面、替换原有混凝土桥面、加固传统正交异性钢桥面板以及新建正交异性夹层钢桥面板等方面的应用情况和研究进展,结果表明S PS 夹层板非常适合在以受弯为主的板式结构中采用,已建成的SPS夹层桥面结构也表现出可靠的力学性能。最后对SPS夹层板的数值建模方法进行讨论,并提出今后应在界面粘结滑移、标准化构造细节、通用设计方法等方面重点开展研究。

  4. Structural performance of complex core systems for FRP-balsa composite sandwich bridge decks

    OpenAIRE

    Osei-Antwi, Michael

    2014-01-01

    Based on current fiber-reinforced polymer (FRP) composite construction principles, FRP decks fall into two categories: pultruded decks and sandwich decks. Sandwich decks comprise face sheets and either honeycombs or foams reinforced with internal FRP webs for shear resistance. The honeycomb structure and the webs cause debonding between the upper face sheets and the core due to the uneven support of the former. An alternative material that has high shear capacity and can provide uniform ...

  5. Multi-mode traffic-induced vibrations in composite ladder-deck bridges under heavy moving vehicles

    Science.gov (United States)

    Camara, A.; Ruiz-Teran, A. M.

    2015-10-01

    Composite (steel-concrete) ladder-decks represent one of the most common solutions in road bridges nowadays. In these structures the Serviceability Limit State (SLS) of vibrations is traditionally ignored or roughly addressed by means of simple static deflection-based approaches, inherently assuming that the vibrations are controlled by the fundamental longitudinal mode. This work demonstrates that a wide range of high-order vibrational modes, involving the transverse flexure of the slab between longitudinal girders, govern the accelerations recorded in the deck and inside the vehicles. In addition, a new methodology for analysing the Vehicle-Bridge Interaction is proposed, including the approaching platforms, the transition slabs, and the bridge joints. The results suggest that the riding comfort for vehicle users is specially affected by direct effects on the wheels, like the road roughness and possible construction misalignments at the bridge joints, as well as low-frequency vibrations coming from the deck in short or slender bridges. The filtering effects resulting from the average of the response in time and in space when calculating the root mean square acceleration are also explored, and new design parameters are provided. In addition, several structural features (such as the depth and spacing of the longitudinal and transverse steel beams, the thickness of the concrete slab, and the stiffness of the cantilever cross beams at the diaphragm sections) have been studied, and a set of new design criteria has been established. It has been demonstrated that the transverse flexibility of the deck (specially influenced by the support conditions and the slab thickness) is critically important for the users' (pedestrians and vehicle passengers) comfort, as it controls the aforementioned high-order vibrational modes which govern the dynamic response.

  6. Effect of cracking and randomness of inputs on corrosion initiation of reinforced concrete bridge decks exposed to chlorides

    Directory of Open Access Journals (Sweden)

    P. Konecny

    2017-01-01

    Full Text Available The paper is aimed at the indicative evaluation of the effect of random scatter of input parameters in case of durability of reinforced concrete bridge deck. The time to onset of corrosion of steel reinforcement of concrete bridge deck exposed to chloride is evaluated. The effect of cracking in concrete onto chloride ingress is considered. The selected steel reinforcement protection strategies are: unprotected steel reinforcement, epoxy-coated steel reinforcement and water-proof barrier bellow asphalt overlay. The preliminary model for damage effect on chloride ion ingress through water proof membrane under penetrable asphalt overlay is used. 2-D finite element chloride ingress model is combined with Monte Carlo simulation technique. The innovative crack effect modeling via highly penetrable elements is applied. Deterministic and probabilistic calculations are compared.

  7. Modeling of Multi-Layered Protection Systems for Chloride Penetration in Concrete Bridge Decks

    Science.gov (United States)

    Harajli, Ali A.

    Modeling of Multi-Layered Protection Systems for Chloride Penetration in Concrete Bridge Decks. This paper covers the development of a new methodology for predicting the chloride concentration and corrosion initiation times for a multi-layer protection overlay system. The first topic will be presenting an innovative method to predict the chloride concentrations using different diffusion coefficients for each protective layer. The new method covers the cases where the applied surface chloride concentrations are either a constant or linear functions with time. The second topic will implement the results from field data about the chloride variations due to the presence of applied topical layers for comparison with the theoretical models. This section will also apply damage factors that are time-dependent to simulate external factors such as traffic loading or vibrations. The third topic will investigate the sensitivity of the single and multi-layer systems due to diffusivity parameter changes. The fourth topic will analyze the random variation of the diffusivity values to predict the mean and standard deviation of chloride concentrations. The diffusivity values are selected from published values by NIST and are based on certain water cement (w/c) ratios.

  8. Evaluation of undersized bioretention stormwater control measures for treatment of highway bridge deck runoff.

    Science.gov (United States)

    Luell, S K; Hunt, W F; Winston, R J

    2011-01-01

    Two grassed bioretention cells were constructed in the easement of a bridge deck in Knightdale, North Carolina, USA, in October, 2009. One was intentionally undersized ('small'), while the other was full sized ('large') per current North Carolina standards. The large and small cells captured runoff from the 25- and 8-mm events, respectively. Both bioretention cells employed average fill media depths of 0.65 m and internal water storage (IWS) zones of 0.6 m. Flow-proportional, composite water quality samples were collected and analyzed for nitrogen species, phosphorus species, and TSS. During 13 months of data collection, the large cell's median effluent concentrations and loads were less than those from the small cell. The small cell's TN and TSS load reductions were 84 and 50%, respectively, of those achieved by the large cell, with both cells significantly reducing TN and TSS. TP loads were not significantly reduced by either cell, likely due to low TP concentrations in the highway runoff which may have approached irreducible levels. Outflow pollutant loads from the large and small cell were not significantly different from one another for any of the examined pollutants. The small cell's relative performance provides support for retrofitting undersized systems in urbanized areas where there is insufficient space available for conventional full-sized stormwater treatment systems.

  9. Assessment of the Reliability Profiles for Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper calculation of reliability profiles is discussed. ULS as well as SLS limit states are formulated. Corrosion due to chloride penetration is the considered deterioration mechanism. Three models for corrosion are formulated. A definition of service lifetime for concrete bridges...... is presented and discussed. The proposed method of calculating reliability profiles is illustrated on an exiting U.K. bridge....

  10. Reliability assessment of offshore platforms exposed to wave-in-deck loading. Appendix F: Reliability analysis of offshore jacket structures with wave load on deck using the model correction factor method

    Energy Technology Data Exchange (ETDEWEB)

    Dalsgaard Soerensen, J. [Aalborg Univ., Aalborg (Denmark); Friis-Hansen, P. [Technical Univ. Denmark, Lyngby (Denmark); Bloch, A.; Svejgaard Nielsen, J. [Ramboell, Esbjerg (Denmark)

    2004-08-01

    Different simple stochastic models for failure related to pushover collapse are investigated. Next, a method is proposed to estimate the reliability of real offshore jacket structures. The method is based on the Model Correction Factor Method and can be used to very efficiently to estimate the reliability for total failure/collapse of jacket type platforms with wave in deck loads. A realistic example is evaluated and it is seen that it is possible to perform probabilistic reliability analysis for collapse of a jacket type platform using the model correction factor method. The total number of deterministic, complicated, non-linear (RONJA) analysis is typically as low as 10. Such reliability analyses are recommended to be used in practical applications, especially for cases with wave in deck load, where the traditional RSR analyses give poor measures of the structural reliability. (au)

  11. Experimental evaluation of the buckling phenomena in the new joint design for upper deck structure of a bridge

    Directory of Open Access Journals (Sweden)

    Solazzi L.

    2010-06-01

    Full Text Available This paper is concerned with the experimental mechanical analysis of a new design of a joint for a main components of a upper deck of a road bridge. These components are subject to the compression state stress induced by the weight and the load acting on the road. Each upper deck of a bridge (positioned on each side of the bridge is composed by four tubular structures that must be joint each together. The joint must to take in to account many aspects, for example that the length of each component is not the same (because, obviously, there is a mechanical tolerance. This phenomena induce different compression stress on each component and so is very important non only the critical buckling load but also the post buckling behaviour of the structure. It is very important that if a single tubular structure reaches the critical load of instability, it still has load capacity . This is to avoid that, in the case where a column reaches the instability, the entire load acting on a column increase the load on the remaining three. For this purpose many different geometrical solutions have been designed (elaborated by fem analyses and successively tested experimentally. This work reports the main experimental results on the best joint solution and how this increase the load capacity and the displacement respect to the solution without this flange.

  12. 水泥混凝土桥面铺装施工质量控制%Pavement construction quality control of cement concrete bridge deck

    Institute of Scientific and Technical Information of China (English)

    贾志民

    2009-01-01

    Combining with construction practice of the bridge deck pavement, the author introduces the quality control points in the cement concrete bridge deck pavement construction from aspects of hinge joint concrete construction and bridge deck pavement concrete construction, so as to perfect bridge deck pavement construction technology, ensure that the bridge deck concrete pavement layer has design strength, in-tegrity and anti-permeability, anti-crack and anti-impact performance.%结合桥面铺装的施工实践,从铰缝混凝土施工和桥面铺装混凝土施工两方面介绍了水泥混凝土桥面铺装施工中的质量控制要点,以完善桥面铺装施工工艺,保证桥面混凝土铺装层具有设计强度、整体性及抗渗抗裂抗冲击性.

  13. Reliability assessment of welded steel details in bridges using inspection

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard; Yalamas, T.

    2014-01-01

    of the membrane stresses are estimated using a generic bridge structure and traffic measurements. The optimal reliability level for a welded detail in a bridge subjected to fatigue are estimated by cost benefit-analysis taking into account the risk of human lives through the Life Quality Index. Since the optimal...

  14. Assessment of the Reliability of Concrete Slab Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle; Jensen, F. M.; Middleton, C. R.

    This paper is based on research performed for the Highways 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....

  15. Development and construction of low-cracking high-performance concrete (LC-HPC) bridge decks: Free shrinkage tests, restrained ring tests, construction experience, and crack survey results

    Science.gov (United States)

    Yuan, Jiqiu

    2011-12-01

    The development, construction, and evaluation of low-cracking high-performance concrete (LC-HPC) bridge decks are described based on laboratory test results and experiences gained during the construction of 13 LC-HPC bridge decks in Kansas, along with another deck bid under the LC-HPC specifications but for which the owner did not enforce the specification. This study is divided into four parts covering (1) an evaluation of the free shrinkage properties of LC-HPC candidate mixtures, (2) an investigation of the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete, (3) a study of the restrained shrinkage performance of concrete using restrained ring tests, and (4) a description of the construction and preliminary evaluation of LC-HPC and control bridge decks constructed in Kansas. The first portion of the study involves evaluating the effects of the duration of curing, fly ash, and a shrinkage reducing admixture (SRA) on the free-shrinkage characteristics of concrete mixtures. The results indicate that an increase of curing period reduces free shrinkage. With 7 days of curing, concretes containing fly ash as a partial replacement for cement exhibit higher free shrinkage than concretes with 100% portland cement. When the curing period is increased to 14, 28, and 56 days, the adverse effect of adding fly ash on free shrinkage is minimized and finally reversed. The addition of an SRA significantly reduces free shrinkage for both the 100% portland cement mixture and the mixture containing fly ash. The second portion of the study investigates the relationship between the evaporable water content in the cement paste and the free shrinkage of concrete. A linear relationship between free shrinkage and evaporable water content in the cement paste is observed. For a given mixture, specimens cured for a longer period contain less evaporable water and exhibit lower free shrinkage and less weight loss in the free shrinkage

  16. 正交异性钢桥面板横隔板切口疲劳应力幅分析%ANALYSIS OF FATIGUE STRESS AMPLITUDE OF DIAPHRAGM NOTCH IN ORTHOTROPIC STEEL BRIDGE DECK

    Institute of Scientific and Technical Information of China (English)

    吉伯海; 田圆; 傅中秋; 徐汉江

    2014-01-01

    建立全桥模型和简化的钢桥面板局部节段模型,通过子模型法插值得到横隔板疲劳细节模型的边界条件,计算不同车轮横向分布对应的疲劳细节局部应力,研究横隔板参数变化对横隔板疲劳细节损伤的影响。结果表明:混合单元模型与钢桥面板简化模型对应的应力幅相差小于5.0%,采用钢桥面板简化模型分析横隔板疲劳细节受力简单合理。横隔板疲劳细节在车轮偏离中心位置150 mm时应力幅最大,随着车轮偏离中心位置距离的增大,应力幅下降明显。横隔板间距增大,横隔板疲劳细节应力幅上升,增加横隔板厚度可有效改善其疲劳受力性状。%The overall bridge FE model and simplified steel bridge deck FE model were built .The boundary conditions of diaphragm fatigue detail FEM were interpolated from the FEM of the steel bridge deck .The local stresses under variable wheels lateral distribution were calculated .Influence of diaphragm ’ s parameters on fatigue damage of diaphragm fatigue detail was investigated .The results showed that the differences of stress amplitude between the FEM of mixed-element and simplified steel bridge deck were less than 5.0%.It was simple and reliable to calculate the fatigue stress of diaphragm fatigue detail by using steel bridge deck model .Stress amplitude of diaphragm fatigue detail reached maximum when the off-center distance of wheel position was 150 mm, which decreased obviously with the increasing off-center distance of wheel position .Stress amplitude of diaphragm fatigue detail increased with the increasing interval of diaphragms .And increasing diaphragm ’ s thickness could improve the fatigue behavior of stress of steel bridge deck .

  17. Structural reliability of existing city bridges

    NARCIS (Netherlands)

    Hellebrandt, L.; Steenbergen, R.; Vrouwenvelder, T.; Blom, K.

    2015-01-01

    Full probabilistic reliability analysis may be valuable for assessing existing structures. Measures for increasing the safety level are quite costly for existing structures and may be unnecessary when such a decision is grounded on a conservative analysis for determining the structural reliability.

  18. Post-stressed constant depth beam concrete road and railway bridge voided decks morphology; Morfologia de tableros aligerados de canto constante postesados para puentes carreteros y ferroviarios

    Energy Technology Data Exchange (ETDEWEB)

    Yepes, V.; Alcala, J.; Diaz, J.; Gonzalez-Vidosa, F.

    2011-07-01

    In the work a study to statistically characterise 82 prestressed concrete bridge decks of real flyovers of constant depth are treated. The main objective of the study is to find design formulae with the least number of data so as to improve the preliminary design of this type of structures. The study performs an exploratory analysis and a multivariate analysis of the geometrical variables, the amount of materials and the cost for voided decks. The regression models have allowed predicting the depth of the deck as function of the span and the external void. The depth is the variable that better explains (51,9%) the cost per unit surface of the deck in road bridges, while for railway decks this variable only explains in the order of 23,4%, what implies more independent variables. The main spans and the total length in the case of the railway deck are enough to find the preliminary design of the slab with reasonable accuracy for the economic assessment of the design. (Author) 17 refs.

  19. Experimental Study on Sandwich Bridge Decks with GFRP Face Sheets and a Foam-Web Core Loaded under Two-Way Bending

    Directory of Open Access Journals (Sweden)

    Ruili Huo

    2015-01-01

    Full Text Available In recent years, the sandwich bridge decks with GFRP face sheets and light weight material core have been widely used in the world due to their advantages of low cost, high strength to weight ratios, and corrosion resisting. However, as the bridge decks, most of them are used in foot bridges rather than highway bridges because the ultimate bending strength and initial bending stiffness are relatively low. To address this issue and expand the scope of use, a simple and innovative sandwich bridge deck with GFRP face sheets and a foam-web core, manufactured by vacuum assisted resin infusion process, is developed. An experimental study was carried out to validate the effectiveness of this panel for increasing the ultimate bending strength and initial bending stiffness under two-way bending. The effects of face sheet thickness, foam density, web thickness, and web spacing on displacement ductility and energy dissipation were also investigated. Test results showed that, compared to the normal foam-core sandwich decks, an average approximately 657.1% increase in the ultimate bending strength can be achieved. Furthermore, the bending stiffness, displacement ductility, and energy dissipation can be enhanced by increasing web thickness, web height, and face sheet thickness or decreasing web spacing.

  20. Experimental study of membrane fatigue response for asphalt multisurfacing systems on orthotropic steel deck bridges

    NARCIS (Netherlands)

    Liu, X.; Tzimiris, G.; Scarpas, T.; Hofman, R.; Voskuilen, J.

    2014-01-01

    In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage

  1. Test method to assess membrane layers fatigue response on orthotropic steel bridge decks

    NARCIS (Netherlands)

    Liu, X.; Tzimiris, G.; Li, J.; Scarpas, T.; Hofman, R.; Voskuilen, J.

    2015-01-01

    In order to adequately characterize the fatigue response of the various membranes with surrounding multilayer surfacing layers on orthotropic steel decks and collect the necessary parameters for FE modeling, the details of the cyclic Membrane Adhesion Tester (MAT) are introduced. The fatigue damage

  2. Bridging Resilience Engineering and Human Reliability Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Ronald L. Boring

    2010-06-01

    There has been strong interest in the new and emerging field called resilience engineering. This field has been quick to align itself with many existing safety disciplines, but it has also distanced itself from the field of human reliability analysis. To date, the discussion has been somewhat one-sided, with much discussion about the new insights afforded by resilience engineering. This paper presents an attempt to address resilience engineering from the perspective of human reliability analysis (HRA). It is argued that HRA shares much in common with resilience engineering and that, in fact, it can help strengthen nascent ideas in resilience engineering. This paper seeks to clarify and ultimately refute the arguments that have served to divide HRA and resilience engineering.

  3. Bridge deck surface temperature monitoring by infrared thermography and inner structure identification using PPT and PCT analysis methods

    Science.gov (United States)

    Dumoulin, Jean

    2013-04-01

    One of the objectives of ISTIMES project was to evaluate the potentialities offered by the integration of different electromagnetic techniques able to perform non-invasive diagnostics for surveillance and monitoring of transport infrastructures. Among the EM methods investigated, we focused our research and development efforts on uncooled infrared camera techniques due to their promising potential level of dissemination linked to their relative low cost on the market. On the other hand, works were also carried out to identify well adapted implementation protocols and key limits of Pulse Phase Thermography (PPT) and Principal Component Thermography (PCT) processing methods to analyse thermal image sequence and retrieve information about the inner structure. So the first part of this research works addresses infrared thermography measurement when it is used in quantitative mode (not in laboratory conditions) and not in qualitative mode (vision applied to survey). In such context, it requires to process in real time thermal radiative corrections on raw data acquired to take into account influences of natural environment evolution with time, thanks to additional measurements. But, camera sensor has to be enough smart to apply in real time calibration law and radiometric corrections in a varying atmosphere. So, a complete measurement system was studied and developed [1] with low cost infrared cameras available on the market. In the system developed, infrared camera is coupled with other sensors to feed simplified radiative models running, in real time, on GPU available on small PC. The whole measurement system was implemented on the "Musmeci" bridge located in Potenza (Italy). No traffic interruption was required during the mounting of our measurement system. The infrared camera was fixed on top of a mast at 6 m elevation from the surface of the bridge deck. A small weather station was added on the same mast at 1 m under the camera. A GPS antenna was also fixed at the

  4. Nonlinear Dynamic Reliability of Coupled Stay Cables and Bridge Tower

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Nonlinear vibration can cause serious problems in long span cable-stayed bridges. When the internal resonance threshold is reached between the excitation frequency and natural frequency,large amplitudes occur in the cable. Based on the current situation of lacking corresponding constraint criteria, a model was presented for analyzing the dynamic reliability of coupling oscillation between the cable and tower in a cable-stayed bridge. First of all, in the case of cable sag, the d'Alembert principle is applied to studying the nonlinear dynamic behavior of the structure, and resonance failure interval of parametric oscillation is calculated accordingly. Then the dynamic reliability model is set up using the JC method. An application of this model has been developed for the preliminary design of one cable-stayed bridge located on Hai River in Tianjin, and time histories analysis as well as reliability indexes have been obtained. When frequency ratio between the cable and tower is approaching 1∶2, the reliability index is 0.98, indicating high failure probability. And this is consistent with theoretical derivation and experimental results in reference. This model, which is capable of computing the reliability index of resonance failure, provides theoretical basis for the establishment of corresponding rule.

  5. Reliability-based Assessment of Fatigue Life for Bridges

    DEFF Research Database (Denmark)

    Toft, Henrik Stensgaard; Sørensen, John Dalsgaard

    2012-01-01

    The reliability level for bridges is discussed based on a comparison of the reliability levels proposed and used by e.g. JCSS, ISO, NKB and Eurocodes. The influence of reserve capacity by which failure of a specific detail does not lead to structural collapse is investigated. The results show...... of regular inspections into account. In an illustrative example the reliability level for a set of typical welded steel details is investigated along with the influence of different inspection methods. The results show that the reliability level can be significantly increased by applying regular inspections....... However, the accuracy of the inspection methods has a significant influence on how much the reliability level is increased by an inspection....

  6. Some considerations on the effects of the P-derivatives on bridge deck flutter

    Science.gov (United States)

    Zhang, Xin; Brownjohn, James Mark William

    2005-05-01

    Using two degrees of freedom (dof) experimental flutter derivatives to perform three-dimensional flutter analysis for a cable-supported bridge is a widely practiced method. It is important to consider the P-derivatives effect to have more accurate analysis for a long-span bridge. Through a case example, this paper studied some of the issues relating to the P-derivatives effects on flutter. The operational condition in two-dof experiments was discussed. It was suggested that due to the strong aeroelastic coupling effect of the sectional model studied in this research, there was an inherent weakness of two-dof experiments. The effect of the P-derivatives was studied for an example bridge by comparing the flutter analysis results using two-dof and three-dof experimental flutter derivatives.

  7. Software Reliability Cases: The Bridge Between Hardware, Software and System Safety and Reliability

    Energy Technology Data Exchange (ETDEWEB)

    Herrmann, D.S.; Peercy, D.E.

    1999-01-08

    High integrity/high consequence systems must be safe and reliable; hence it is only logical that both software safety and software reliability cases should be developed. Risk assessments in safety cases evaluate the severity of the consequences of a hazard and the likelihood of it occurring. The likelihood is directly related to system and software reliability predictions. Software reliability cases, as promoted by SAE JA 1002 and 1003, provide a practical approach to bridge the gap between hardware reliability, software reliability, and system safety and reliability by using a common methodology and information structure. They also facilitate early insight into whether or not a project is on track for meeting stated safety and reliability goals, while facilitating an informed assessment by regulatory and/or contractual authorities.

  8. 桥面铺装与小箱梁的共同作用试验%Experiment of Coaction of Bridge Deck Pavement and Small Box Girder

    Institute of Scientific and Technical Information of China (English)

    钱寅泉; 周正茂; 袁桂芳; 王素娟

    2012-01-01

    Load tests on a single small box girder and a bridge were carried out to evaluate the effects of deck pavement by comparing the deflections of the girders before and after the pavement surfaced. The comprehensive elastic modulus was obtained from the test before pavement surfaced, and the coaction degree of the bridge deck pavement and the girders was obtained by comparing the flexural inertia moment corresponding to the deflection in the test after pavement surfaced with the theoretical flexural inertia moment corresponding to the supposed thickness of the pavement in work. The results from these tests show that (1) the rough interface could greatly improve the coaction degree of bridge deck pavement with girders, which could reach 100% ; (2) in general cases, the extent of the coaction of bridge deck pavement with girders could reach 70% , and for a pavement with thickness of 8 cm, the thickness of the pavement in coaction could be taken as 60% or 3 cm in thickness could be substracted from the pavement in design; (3 ) the pavement could improve the uniformity of the transverse load distribution. Load tests on a single small box girder and a bridge were carried out to evaluate the effects of deck pavement by comparing the deflections of the girders before and after the pavement surfaced. The comprehensive elastic modulus was obtained from the test before pavement surfaced, and the coaction degree of the bridge deck pavement and the girders was obtained by comparing the flexural inertia moment corresponding to the deflection in the test after pavement surfaced with the theoretical flexural inertia moment corresponding to the supposed thickness of the pavement in work. The results from these tests show that (1) the rough interface could greatly improve the coaction degree of bridge deck pavement with girders, which could reach 100% ; (2) in general cases, the extent of the coaction of bridge deck pavement with girders could reach 70% , and for a pavement with

  9. Steel bridge deck pavement design index analysis of the highway bridge in Maanshan Yangtze River%马鞍山长江公路大桥钢桥面铺装设计指标分析

    Institute of Scientific and Technical Information of China (English)

    詹成根; 王民; 张昭

    2014-01-01

    对马鞍山长江公路大桥钢桥面铺装技术难点进行了分析,并确定了设计要求。参考国内类似结构的多种大跨径悬索桥钢桥面铺装设计指标,从使用条件、工程实践及试验研究等角度出发,对比分析了钢桥面铺装设计指标。结合该桥整体结构变形和荷载响应特性,制定了钢桥面铺装结构层设计指标。该研究成果对改善钢桥面铺装的结构性能和提高钢桥面铺的使用寿命具有重要的意义。%By analyzing technical difficulties of Maanshan Yangtze River highway bridge steel bridge deck pavement,the design requirements are determined.Considering do-mestic similar structures of long-span steel bridge deck pavement design index of sus-pension bridges,the operation conditions,engineering practice and experimental studies are compared.According to the overall structure deformation,load response characteris-tics,design index for steel bridge deck pavement structure layer,research achievements of scientific improvement are obtained,which can improve the performance and increase the service life of the steel bridge deck pavement structure.This work has important significance.

  10. HERMES: a high-speed radar imaging system for inspection of bridge decks

    Energy Technology Data Exchange (ETDEWEB)

    Azevedo, S.G.

    1996-10-26

    Corrosion of rebar in concrete bridges causes subsurface cracks and is a major cause of structural degradation that necessitates repair or replacement. Early detection of corrosion effects can limit the location and extent of necessary repairs, while providing long-term information about the infrastructure status. Most current detection methods, however, are destructive of the road surface and require closing or restricting traffic while the tests are performed. A ground-penetrating radar imaging system has been designed and developed that will perform the nondestructive evaluation of road-bed cracking at traffic speeds; i.e., without the need to restrict traffic flow. The first-generation system (called the HERMES bridge inspector), consists of an offset-linear array of 64 impulse radar transceivers and associated electronics housed in a trailer. Computers in the trailer and in the towing vehicle control the data acquisition, processing, and display. Cross-road resolution is three centimeters at up to 30 cm in depth, while down-road resolution depends on speed; 3 cm below 20 mph up to 8 cm at 50 mph. A two-meter- wide path is inspected on each pass over the roadway. This paper, describes the design of this system, shows preliminary results, and lays out its deployment schedule.

  11. 钢主梁拱桥组合桥面系力学性能分析%MECHANICAL BEHAVIOR ANALYSIS OF COMPOSITE DECK FLOOR OF ARCH BRIDGE WITH STEEL GIRDER

    Institute of Scientific and Technical Information of China (English)

    苏庆田; 李杰; 董冰

    2012-01-01

    钢-混凝土组合结构桥面系近几年开始在拱桥结构中使用,拱桥中组合桥面系受力复杂,其力学性能受钢与混凝土是否连接、是否张拉系杆以及混凝土的浇注顺序等影响.该文采用空间有限元模型,开展了钢主梁拱桥组合桥面系的力学性能研究.研究表明:在钢主梁拱桥结构中混凝土桥面板与钢主梁是否结合对桥面系的整体受力影响甚微,只对桥面系局部位置的混凝土桥面板应力分布有所影响;拱桥中是否安装系杆对桥面系的受力影响较大,而且桥面系的受力与系杆张拉力有密切关系;对于组合桥面系的拱桥采用一次浇筑混凝土桥面板施工方法的桥面系受力要明显优于采用分段浇筑混凝土桥面板的方法.%A steel-concrete composite deck has been used in acrh bridges recently. The mechanism of a composite deck is complex, and was affected by the factors of setting connections between concrete decks and steel girder or not, setting tied bars or not, different deck concrete casting sequences etc. In this paper, mechanical behaviors of a composite deck floor of an arch bridge with steel girders are analyzed by a spatial finite element model. The research results show that whether setting connections between concrete decks and a steel girder or not slightly affects the total mechanical behavior of a deck floor but influents the local stress of the deck; whether setting tied bar affects the deck floor mechanical property greatly and the deck floor stress depends on the tension force of tied bars heavily; as to arch bridge with a composite deck floor, the mechanical behavior of deck floors with casting deck concrete by one time is superior to that of deck floors with casting deck concrete by several times.

  12. 基于可靠度的组合桥梁设计及维护策略%Reliability-Based Design and Maintenance Strategy for Composite Bridges

    Institute of Scientific and Technical Information of China (English)

    张慕圣; 陈锐斌

    2012-01-01

    Currently,the design practice of highway bridges around the world are moving towards limit states design,a reliability-based design procedure.Canadian Highway Bridge Design Code (CHBDC) is the first design code entirely developed based on limit states design philosophy,including foundations and FRP components.However,reliability of a structure decreases in service due to environmental attacks and material deterioration such as fatigue,corrosion and many other reasons.Therefore,the structure should be inspected periodically,and the reliability of the structure should be evaluated according to its age and field data.If its reliability is reduced to a certain level,a repair should be scheduled as well as some preventive maintenance measures should be implemented to prevent further deterioration.Recently,many research works have been conducted to investigate reliability-deterioration mechanisms for each type of infrastructure and its components,optimize the inspection and maintenance strategy,predict remaining service life,estimate its life cycle cost.This paper is focused on the study of reliability-deterioration mechanisms of slab on steel girder bridges due to fatigue and corrosion of steel girders as well as corrosion of reinforcement in the deck slab.Examples will also be given to illustrate the proposed life cycle management strategy for composite slab on steel girder bridges.

  13. 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.

  14. Aluminium bridges, aluminium bridge decks

    NARCIS (Netherlands)

    Soetens, F.; Straalen, IJ.J. van

    2003-01-01

    Applications of aluminium have grown considerably in building and civil engineering the last decade. In building and civil engineering the increase of aluminium applications is due to various aspects like light weight, durability and maintenance, use of extrusions, and esthetics. The paper starts

  15. Aluminium bridges, aluminium bridge decks

    NARCIS (Netherlands)

    Soetens, F.; Straalen, IJ.J. van

    2003-01-01

    Applications of aluminium have grown considerably in building and civil engineering the last decade. In building and civil engineering the increase of aluminium applications is due to various aspects like light weight, durability and maintenance, use of extrusions, and esthetics. The paper starts wi

  16. 基于桥面铺装技术的城市高架桥梁设计研究%Urban Elevated Bridge Design Based on Deck Pavement Technology

    Institute of Scientific and Technical Information of China (English)

    宋殿峰

    2014-01-01

    This article expounds the deck pavement techn-ology of urban elevated bridge and points out the existing problems, and puts forward pavement construction, joints treatment and other technical processing measures through analyzes the deck pavement technology of urban elevated bridge.%本文对城市高架桥梁桥面铺装工艺进行了阐述,指出面铺装存在的问题,通过对高架桥桥面铺装技术的分析,提出了摊铺施工、接缝处理等技术处理举措。

  17. Reliability-Based Optimization for Maintenance Management in Bridge Networks

    OpenAIRE

    Hu, Xiaofei

    2014-01-01

    This dissertation addresses the problem of optimizing maintenance, repair and reconstruction decisions for bridge networks. Incorporating network topologies into bridge management problems is computationally difficult. Because of the interdependencies among networked bridges, they have to be analyzed together. Simulation-based numerical optimization techniques adopted in past research are limited to networks of moderate sizes. In this dissertation, novel approaches are developed to dete...

  18. Future Trends in Reliability-Based Bridge Management

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    Future bridge management systems will be based on simple stochastic models predicting the residual strength of structural elements. The current deterministic management systems are not effective in optimizing e.g. the life cycle cost of a bridge or a system of bridges. A number of important factors...

  19. Preliminary Investigation of the Systematic Approach to the Repair Versus Replacement Decision-Making Process for Deteriorated Concrete Bridge Decks.

    Science.gov (United States)

    1986-06-26

    Developing State Transportation Programs.............. 161 6.3 Bridge Management System ................... 163 6.4 Components of the Systematic Decision...144 Figure 6-1 Schematic of State Transportation Management and Bridge Management System .................................... 160 Figure 6-2...briefly highlights the general concepts associated with an overall bridge management system . Specifically, the chap- ter identifies the components or the

  20. On Reliability Based Optimal Design of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In recent years important progress has been made in assessment of the lifetime behaviour of concrete bridges. Due to the large uncertainties related to the loading and the deterioration of such bridges, an assessment based on stochastic modelling of the significant parameters seems to be only rel...

  1. Fatigue damage reliability analysis for Nanjing Yangtze river bridge using structural health monitoring data

    Institute of Scientific and Technical Information of China (English)

    HE Xu-hui; CHEN Zheng-qing; YU Zhi-wu; HUANG Fang-lin

    2006-01-01

    To evaluate the fatigue damage reliability of critical members of the Nanjing Yangtze river bridge, according to the stress-number curve and Miner's rule, the corresponding expressions for calculating the structural fatigue damage reliability were derived. Fatigue damage reliability analysis of some critical members of the Nanjing Yangtze river bridge was carried out by using the strain-time histories measured by the structural health monitoring system of the bridge. The corresponding stress spectra were obtained by the real-time rain-flow counting method.Results of fatigue damage were calculated respectively by the reliability method at different reliability and compared with Miner's rule. The results show that the fatigue damage of critical members of the Nanjing Yangtze river bridge is very small due to its low live-load stress level.

  2. Design of Bridge Deck with Intelligent Temperature Control and Deicing System%智能控温防冻桥面的构思和设计

    Institute of Scientific and Technical Information of China (English)

    谭红霞; 涂莉; 李建男

    2012-01-01

    It is cold winter in China,and the cold weather lasts almost one month in south China and even longer in the north.So,the road surface and bridge deck get iced up easily.The traffic accidents and high-way closures caused by icing will bring huge negative social influence and economic losses,so it is necessary to take effective decicing methods.However,some of the current deicing methods,have both advantages and disadvantages.Accordingly,this paper proposes a new method:replace a row of reinforcement steel bar with steel pipes in the steel mesh and lay heating wires in the pipes to heat up he bridge deck.The entire circuit control system takes the advantage of automatic temperature control.When the deck temperature is lower than 2 ℃,the temperature control system automatically switch on the power,and wires warm up;when the deck temperature is higher than 20 ℃,the temperature control system automatically switch off the power,wires stop warming.In this way,intelligent temperature control is achieved,and at the same time,the deck will not be iced up in low temperature.This system is easy to repair when with a fault,thus ensuring safe transportation.%中国冬季天气寒冷,路面桥面容易结冰,南方结冰期近1个月,北方时间更长.结冰引起的交通事故和高速公路关闭带来巨大的社会影响和经济损失,故急需采取有效的方法防止路面结冰.利用在桥面铺装层中的钢筋网,修改一个方向的钢筋为钢管,钢管中敷设发热丝,对桥面加热,整个电路使用控制系统根据温度变化自动控制.当桥面温度低于2℃时,控温系统自动接通电源,发热丝发热,加热桥面,当桥面温度高于20℃时,控温系统自动断开电源,发热丝停止加热桥面,从而实现温度智能可控,并且低温时路面不会结冰,故障时易于检修,车辆能安全通行.

  3. Semiempirical Methodology for Estimating the Service Life of Concrete Deck Panels Strengthened with Fiber-Reinforced Polymer

    Directory of Open Access Journals (Sweden)

    Eon-Kyoung Kim

    2014-01-01

    Full Text Available Deterioration of concrete bridge decks affects their durability, safety, and function. It is therefore necessary to conduct structural rehabilitation of damaged concrete decks by strengthening them with fiber-reinforced polymer. Of the recent studies on the strengthened structures, most have focused on static behavior; only a few studies have investigated fatigue behavior. Accurate analysis of fatigue in concrete deck performance requires a more realistic simulated moving load. This study developed a theoretical live-load model to reflect the effect of moving vehicle loads, based on a statistical approach to the measurement of real traffic loads over various time periods in Korea. It assessed the fatigue life and strengthening effect of bridge decks strengthened with either carbon fiber sheets or grid carbon fiber polymer plastic using probabilistic and reliability analyses. It used extrapolations and simulations to derive maximum load effects for time periods ranging from 1 day to 75 years. Limited fatigue tests were conducted and probabilistic and reliability analyses were carried out on the strengthened concrete bridge deck specimens to predict the extended fatigue life. Analysis results indicated that strengthened concrete decks provide sufficient resistance against increasing truck loads during the service life of a bridge.

  4. 重庆两江大桥正交异性钢桥面板疲劳性能试验研究%Fatigue test of orthotropic steel bridge deck in Chongqing liangjiang bridge

    Institute of Scientific and Technical Information of China (English)

    叶华文; 徐勋; 强士中; 任伟平

    2013-01-01

    为评估重庆两江大桥正交异性钢桥面板双向荷载下的疲劳性能,对由盖板、板肋和横隔板组成的箱形正交异性钢桥面板模型进行疲劳试验研究和有限元分析.采用应力等效方法,板肋与横隔板交叉细节部分采用1∶1足尺模型,横隔板开孔分别采用苹果形和钥匙形,面内和面外双向疲劳加载完成正交异性板结构设计寿命期及超长服役期的等效实桥疲劳应力幅作用下2 000万次疲劳试验.有限元值和实测值较吻合.在疲劳试验基础上,讨论横隔板开孔边缘、纵肋与横隔板焊接以及纵肋与盖板焊接3个关键部位的疲劳性能.研究结果表明:双向荷载作用下横隔板产生面外弯曲变形,易导致面外疲劳;正交异性钢桥面板构造未发现裂纹,疲劳寿命远超过设计寿命期.根据欧洲规范的疲劳等级分类检算,其疲劳强度满足使用要求.%In order to estimate the biaxial fatigue performance of orthotropic decks in Chongqing Liangjiang cable-stayed bridges, an experimental and numerical investigation was conducted to study the biaxial fatigue behavior of box-shaped orthotropic steel deck specimen composed of deck plate, plate longitudinal ribs and cross beams. Firstly an equivalent stress approach was applied to gain a test model with full scale connection details of the longitudinal rib to cross beam joint and apple- and key- shaped cut-out of the crossbeam. The fatigue behavior was discussed at three locations such as the edge of the cut-out in the cross beam, the longitudinal rib to cross beam joint and the longitudinal rib to deck plate joint, based on the static experimental and numerical results. The fatigue test was carried out under in-plane and out-plane loading during 20 000 000 cycles under equivalent applied stress ranges including design life and limit life. The numerical results are confirmed to agree well with the experimental results. The experimental results show that the

  5. reliability assessment of stringers spacings in bridges as function of ...

    African Journals Online (AJOL)

    user

    Reinforced concrete and steel which have edged out timber as a ... with concrete bridges built that are between forty and fifty years old. ... severe weather and site conditions, which is one of its attractive ... tropics but also as a sustainable development which will help to ...... strength: a linear cumulative damage theory. Wood.

  6. Probabilistic seismic response and reliability assessment of isolated bridges

    Institute of Scientific and Technical Information of China (English)

    Giuseppe Carlo Marano

    2005-01-01

    Bridge seismic isolation strategy is based on the reduction of shear forces transmitted from the superstructure to the piers by two means: shifting natural period and earthquake input energy reduction by dissipation concentrated in protection devices. In this paper, a stochastic analysis of a simple isolated bridge model for different bridge and device parameters is conducted to assess the efficiency of this seismic protection strategy. To achieve this aim, a simple nonlinear softening constitutive law is adopted to model a wide range of isolation devices, characterized by only three essential mechanical parameters. As a consequence of the random nature of seismic motion, a probabilistic analysis is carried out and the time modulated Kanai-Tajimi stochastic process is adopted to represent the seismic action. The response covariance in the state space is obtained by solving the Lyapunov equation for a stochastic linearized system. After a sensitivity analysis, the failure probability referred to extreme displacement and the mean value of dissipated energy are assessed by using the introduced stochastic indices of seismic bridge protection efficiency. A parametric analysis for protective devices with different mechanical parameters is developed for a proper selection of parameters of isolation devices under different situations.

  7. 采用GFRP配筋解决混凝土碳化对桥梁面板的负面影响%THE SOLUTION FOR ADVERSE IMPACT OF CARBONATION ON CONCRETE BRIDGE DECK SLABS BT USING GFRP REINFORCEMENT

    Institute of Scientific and Technical Information of China (English)

    郑愚; 秦怀泉; 李春红

    2009-01-01

    As crucial structural components in bridge structures, bridge deck slabs played an important role in integral structural behaviours and transportation. However, with the increasing of ages in services, the durability of reinforced concrete bridge deck slabs was influenced significantly by carbonation. Recently, because of high strength, light weight and strong corrosion-resistance, glass fiber polymer reinforcement bars (GFRP bars) were accepted by civil engineers. Due to the existence of compressive membrane action, it was shown that the structural behaviours of GFRP reinforced concrete bridge deck slabs with same reinforcement percentage were similar as those of steel reinforced concrete bridge deck slabs in nonlinear finite element analysis. Based on numerical analysis results, GFRP is available to be used as replacement of steel reinforcement. According the analysis of mechanism of concrete carbonation and material properties of GFRP, it was found that the durability of GFRP reinforced concrete bridge deck slabs was enhanced after the occurrence of carbonation in concrete structures, because carbonation reduced the permeability and porosity of concrete.%桥梁面板是桥梁结构的主要构件,对结构的整体性能和交通运输起着至关重要的作用.然而随着使用年限的增加,混凝土碳化将对钢筋混凝土桥梁面板的耐久性能产生较大的影响.近年来,玻璃纤维增强复合筋材(GFRP Bars)因具有高强、轻质、耐腐蚀等性能而逐渐被工程界认可.非线性有限元分析结果表明,由于压缩薄膜效应的存在使得同样配筋率的GFRP筋混凝土桥梁面板与钢筋混凝土桥梁面板的工作性能相似,证实了GFRP筋代替钢筋的可行性.在分析混凝土的碳化机理和GFRP的材料属性后发现,由于碳化使混凝土的渗透性和孔隙率降低,在碳化发生以后GFRP筋混凝土桥梁面的耐久性能不仅没有下降反而有所提高.

  8. 采用GFRP配筋解决混凝土碳化对桥梁面板的负面影响%THE SOLUTION FOR ADVERSE IMPACT OF CARBONATION ON CONCRETE BRIDGE DECK SLABS BY USING GFRP REINFORCEMENT

    Institute of Scientific and Technical Information of China (English)

    郑愚; 秦怀泉; 李春红

    2011-01-01

    As crucial structural components in bridge structures, bridge deck slabs played an important role in integral structural behaviours and transportation. However, with the increasing of ages in services, the durability of reinforced concrete bridge deck slabs was influenced significantly by carbonation. Recently, because of high strength, light weight and strong corrosion-resistance, glass fiber polymer reinforcement bars ( GFRP bars) were accepted by civil engineers. Due to the existence of compressive membrane action, it was shown that the structural be haviours of GFRP reinforced concrete bridge deck slabs with same reinforcement percentage were similar as those of steel reinforced concrete bridge deck slabs in nonlinear finite element analysis. Based on numerical analysis results, GFRP is available to be used as replacement of steel reinforcement. According the analysis of mechanism of concrete carbonation and material properties of GFRP, it was found that the durability of GFRP reinforced concrete bridge deck slabs was enhanced after the occurrence of carbonation in concrete structures, because carbonation reduced the permeability and porosity of concrete.%桥梁面板是桥梁结构的主要构件,对结构的整体性能和交通运输起着至关重要的作用.然而随着使用年限的增加,混凝土碳化将对钢筋混凝土桥梁面板的耐久性能产生较大的影响.近年来,玻璃纤维增强复合筋材( GFRP Bars)因具有高强、轻质、耐腐蚀等性能而逐渐被工程界认可.非线性有限元分析的结果表明,由于压缩薄膜效应的存在使得同样配筋率的GFRP筋混凝土桥梁面板与钢筋混凝土桥梁面板的工作性能相似,证实了GFRP筋代替钢筋的可行性.在分析混凝土的碳化机理和GFRP的材料属性后发现,由于碳化使混凝土的渗透性和孔隙率降低,在碳化发生以后GFRP筋混凝土桥梁面的耐久性能不仅没有下降反而有所提高.

  9. Assessing and updating the reliability of concrete bridges subjected to spatial deterioration - principles and software implementation

    DEFF Research Database (Denmark)

    Schneider, Ronald; Fischer, Johannes; Bügler, Maximilian

    2015-01-01

    . The overall system reliability is computed by means of a probabilistic structural model coupled with the deterioration model. Inspection data are included in the system reliability calculation through Bayesian updating on the basis of the DBN model. As proof of concept, a software prototype is developed...... to implement the method presented here. The software prototype is applied to a typical highway bridge and the influence of inspection information on the system deterioration state and the structural reliability is quantified taking into account the spatial correlation of the corrosion process. This work...... is a step towards developing a software tool that can be used by engineering practitioners to perform reliability assessments of ageing concrete bridges and update their reliability with inspection and monitoring data....

  10. structural reliability of the nigerian grown abura timber bridge beam ...

    African Journals Online (AJOL)

    ENGR. J. I. AGUWA

    2013-07-02

    Jul 2, 2013 ... Structural reliability analysis was carried out on the Nigerian grown Abura timber, to ascertain its structural ... wall sheeting, formwork and furniture. The ... reinforced concrete members. ... fulfill certain performance criteria related to safety and ..... Plastic Structures” First Edition, Mir Publishers. Moscow ...

  11. 城市人行天桥桥面铺装方案研究%The bridge deck pavement scheme research on city pedestrian bridge

    Institute of Scientific and Technical Information of China (English)

    陈娟婷; 田原

    2014-01-01

    Taking the pavement engineering of pedestrian bridge as research object, this paper introduced the pedestrian bridge pavement func-tion and common pavement classification, combining with the actual investigation researched the characteristics and applicability scope of various pavement schemes, and listed and compared, in order to provide some valuable reference for designers in pavement scheme selection.%以人行天桥的铺装工程为研究对象,介绍了天桥铺装的功能与常见的铺装分类,结合实际,调查研究了各种铺装方案的特点和适用范围,并列表加以对比分析,旨在为设计人员在铺装方案的选择上提供一些有价值的参考。

  12. Aerodynamic interaction between road deck and rail deck of separate-type highway-railway bridges and its effect on train running performance%分离式公铁双层桥面相互气动干扰及对列车走行性的影响

    Institute of Scientific and Technical Information of China (English)

    李永乐; 姜孝伟; 苏洋; 李龙安; 廖海黎

    2016-01-01

    There exists aerodynamic interaction between road deck and rail deck of highway-railway bridges under cross wind.In order to investigate the effect of different height intervals between two decks on train running performance, a separate-type highway-railway concrete box girder bridge was taken as an engineering example.The numerical simulation with CFD and the coupled vibration analysis of a wind-vehicle-bridge system were performed to determine train aerodynamic characteristics and to obtain its dynamic response.The results showed that the height interval between two decks has a major influence on train aerodynamic characteristics and its dynamic response;reducing the height interval leads to increase in the train lift coefficient and its vertical acceleration,and the wheel load reduction ratio increases as well;the effect of height intervals between two decks should receive more attention when selecting the optimal height interval in the design of highway-railway bridges.%横向风作用下公铁两用双层桥的上、下桥面间存在相互的气动干扰,为研究公铁两用组合桥间隔高度对列车走行性的影响,针对某分离式公铁两用混凝土箱梁桥,采用计算流体动力学(CFD)数值模拟和风-车-桥耦合振动研究的方法,分析了上、下桥面间隔高度对列车气动特性和车辆动力响应的影响。分析结果表明,公铁两用组合桥间隔高度对列车的气动特性和动力响应影响显著,间隔高度减小,列车升力系数和竖向加速度显著增大,轮重减载率也随之增大。公铁两用组合桥的设计应考虑间隔高度对列车的影响,以选择合理的间隔高度。

  13. Determining the optimum length of a bridge opening with a specified reliability level of water runoff

    Directory of Open Access Journals (Sweden)

    Evdokimov Sergey

    2017-01-01

    Full Text Available Current trends in construction are aimed at providing reliability and safety of engineering facilities. According to the latest government regulations for construction, the scientific approach to engineering research, design, construction and operation of construction projects is a key priority. The reliability of a road depends on a great number of factors and characteristics of their statistical compounds (sequential and parallel. A part of a road with such man-made structures as a bridge or a pipe is considered as a system with a sequential element connection. The overall reliability is the multiplication of the reliability of these elements. The parameters of engineering structures defined by analytical dependences are highly volatile because of the inaccuracy of the defining factors. However each physical parameter is statistically unstable that is evaluated by variable coefficient of their values. It causes the fluctuation in the parameters of engineering structures. Their study may result in the changes in general and particular design rules in order to increase the reliability. The paper gives the grounds for these changes by the example of a bridge. It allows calculating its optimum length with a specified reliability level of water runoff under the bridge.

  14. Reliability analysis of offshore jacket structures with wave load on deck using the Model Correction Factor Method

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Friis-Hansen, P.; Nielsen, J.S.

    2007-01-01

    Traditionally, deterministic pushover analyses are performed for steel-jacket offshore platforms in order to calculate RSR (Reserve Strength Ratio) values as the representative reliability measure for the total collapse of the structure. In this paper, reliability analyses are performed for total...

  15. Reliability Analysis of Offshore Jacket Structures with Wave Load on Deck using the Model Correction Factor Method

    DEFF Research Database (Denmark)

    2006-01-01

    Traditionally deterministic push-over analyses are performed for steel-jacket offshore platforms in order to calculate RSR (Reserve Strength Ratio) values as the representative reliability measure for total collapse of the structure. In this paper reliability analyses are performed for total...

  16. Performance of stress-laminated timber highway bridges in cold climates

    Science.gov (United States)

    James P. Wacker

    2009-01-01

    This paper summarizes recent laboratory and field data studies on thermal performance of stress-laminated timber highway bridges. Concerns about the reliability of stress-laminated deck bridges when exposed to sub-freezing temperatures triggered several investigations. Two laboratory studies were conducted to study the effects of wood species, preservative, moisture...

  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. Demonstration of dual-band infrared thermal imaging for bridge inspection. Phase II, final report

    Energy Technology Data Exchange (ETDEWEB)

    Durbin, P.F.; Del Grande, N.K.; Schaich, P.C.

    1996-03-01

    Developing and implementing methods of effective bridge rehabilitation is a major issue for the Federal Highway Administration (FHWA). The nation spends $5 billion annually to replace, rehabilitate or construct new bridges. According to the National Bridge Inventory, over 100,000 U.S. bridges are structurally deficient. About 40,000 of these bridges have advanced deck deterioration. The most common causes of serious deck deterioration is delamination. Delaminations result when steel reinforcements within the bridge deck corrode, creating gaps that separate the concrete into layers. A reliable inspection technology, capable of identifying delaminations, would represent a power new tool in bridge maintenance. To date, most bridge inspections rely on human interpretation of surface visual features of chain dragging. These methods are slow, disruptive, unreliable and raise serious safety concerns. Infrared thermal imaging detects subsurface delaminations and surface clutter, which is introduced by foreign material on the roadway. Typically, foreign material which is not always evident on a video tape image, produces a unique IR reflectance background unlike the thermal response of a subsurface delamination. Lawrence Livermore National Laboratory (LLNL) uses dual-band infrared (DBIR) thermal imaging to identify and remove nonthermal IR reflectance backgrounds from foreign material on the roadway. DBIR methods improve the performance of IR thermal imaging by a factor of ten, compared to single-band infrared (SBIR) methods. DBIR thermal imaging allows precise temperature measurement to reliably locate bridge deck delaminations and remove wavelength-dependent emissivity variations due to foreign material on the roadway.

  19. The Maintenance Measures of Steel Deck Pavement of Zhoushan Sea-crossing Bridge%舟山跨海大桥钢桥面铺装养护措施

    Institute of Scientific and Technical Information of China (English)

    竺海钢; 曾田; 贺才松

    2015-01-01

    Based on the construction environment and operational requirements of steel deck pavement of Zhoushan Sea-crossing Bridge,the types and causes of steel deck pavement disease are analyzed,and the conservation measures of steel deck epoxy asphalt pavement are proposed.By comparing the construction effects of two rehabilitation programs of double layer epoxy gravel concrete structure and ER structure,the construction feasibility and maintenance rationality of double layer epoxy gravel concrete structure are verified.%基于舟山跨海大桥的施工环境和钢桥面铺装的使用要求,并对钢桥面铺装病害类型及成因进行分析,提出了环氧沥青钢桥面铺装养护措施.通过采用双层环氧碎石混凝土结构和ER结构两种修复方案进行施工对比,验证了双层环氧碎石混凝土结构的施工可行性和维修合理性.

  20. The Maintenance Measures of Steel Deck Pavement of Zhoushan Sea-crossing Bridge%舟山跨海大桥钢桥面铺装养护措施

    Institute of Scientific and Technical Information of China (English)

    竺海钢; 曾田; 贺才松

    2015-01-01

    Based on the construction environment and operational requirements of steel deck pavement of Zhoushan Sea-crossing Bridge,the types and causes of steel deck pavement disease are analyzed,and the conservation measures of steel deck epoxy asphalt pavement are proposed.By comparing the construction effects of two rehabilitation programs of double layer epoxy gravel concrete structure and ER structure,the construction feasibility and maintenance rationality of double layer epoxy gravel concrete structure are verified.%基于舟山跨海大桥的施工环境和钢桥面铺装的使用要求,并对钢桥面铺装病害类型及成因进行分析,提出了环氧沥青钢桥面铺装养护措施。通过采用双层环氧碎石混凝土结构和ER结构两种修复方案进行施工对比,验证了双层环氧碎石混凝土结构的施工可行性和维修合理性。

  1. Optimizing rib width to height and rib spacing to deck plate thickness ratios in orthotropic decks

    Directory of Open Access Journals (Sweden)

    Abdullah Fettahoglu

    2016-12-01

    Full Text Available Orthotropic decks are composed of deck plate, ribs, and cross-beams and are frequently used in industry to span long distances, due to their light structures and load carrying capacities. Trapezoidal ribs are broadly preferred as longitudinal stiffeners in design of orthotropic decks. They supply the required stiffness to the orthotropic deck in traffic direction. Trapezoidal ribs are chosen in industrial applications because of their high torsional and buckling rigidity, less material and welding needs. Rib width, height, spacing, thickness of deck plate are important parameters for designing of orthotropic decks. In the scope of this study, rib width to height and rib spacing to deck plate thickness ratios are assessed by means of the stresses developed under different ratios of these parameters. For this purpose a FE-model of orthotropic bridge is generated, which encompasses the entire bridge geometry and conforms to recommendations given in Eurocode 3 Part 2. Afterwards necessary FE-analyses are performed to reveal the stresses developed under different rib width to height and rib spacing to deck plate thickness ratios. Based on the results obtained in this study, recommendations regarding these ratios are provided for orthotropic steel decks occupying trapezoidal ribs.

  2. Bridging the gap between metallurgy and fatigue reliability of hydraulic turbine runners

    Science.gov (United States)

    Thibault, D.; Gagnon, M.; Godin, S.

    2014-03-01

    The failure of hydraulic turbine runners is a very rare event. Hence, in order to assess the reliability of these components, one cannot rely on statistical models based on the number of failures in a given population. However, as there is a limited number of degradation mechanisms involved, it is possible to use physically-based reliability models. Such models are more complicated but have the advantage of being able to account for physical parameters in the prediction of the evolution of runner degradation. They can therefore propose solutions to help improve reliability. With the use of such models, the effect of materials properties on runner reliability can easily be illustrated. This paper will present a brief review of the Kitagawa-Takahashi diagram that links the damage tolerance approach, based on fracture mechanics, to the stress or strain-life approaches. This diagram is at the centre of the reliability model used in this study. Using simplified response spectra obtained from on-site runner stress measurements, the paper will show how fatigue reliability is impacted by materials fatigue properties, namely fatigue crack propagation behaviour and fatigue limit obtained on S-N curves. It will also present a review of the most important microstructural features of 13%Cr- 4%Ni stainless steels used for runner manufacturing and will review how they influence fatigue properties in an effort to bridge the gap between metallurgy and turbine runners reliability.

  3. 双层桥箱内壁车辆碰撞混凝土损伤仿真研究%Simulation Study on Concrete Damage of the Inner Box Collision of the Double Decked Continuous Box Girder Bridge

    Institute of Scientific and Technical Information of China (English)

    沈正峰; 方金苗; 郑净

    2014-01-01

    Double-decked continuous box bridge is a new structure system and how to evaluate the structure damage caused by vehicle collision inner box has a great significance to the wide application of the new structure .This paper researches all conditions of structure damages caused by vehicle collision inner box by means of computerized simulation .The study finds out the concrete injured parts and its degree ,analysis the sensitive factor of concrete damage ,which provides suggestions for the design of double-decked bridge .%双层连续箱梁桥是一种新型结构体系,如何评价车辆撞击箱梁内部造成的结构损伤对于这种新型结构的广泛运用具有重要意义。通过计算机仿真技术研究各种工况下车辆对箱梁桥内壁撞击引起的结构损伤情况,得出混凝土损伤部位以及程度,分析影响混凝土损伤的敏感因子,为双层桥结构设计提供参考。

  4. Reliability Analysis-Based Numerical Calculation of Metal Structure of Bridge Crane

    Directory of Open Access Journals (Sweden)

    Wenjun Meng

    2013-01-01

    Full Text Available The study introduced a finite element model of DQ75t-28m bridge crane metal structure and made finite element static analysis to obtain the stress response of the dangerous point of metal structure in the most extreme condition. The simulated samples of the random variable and the stress of the dangerous point were successfully obtained through the orthogonal design. Then, we utilized BP neural network nonlinear mapping function trains to get the explicit expression of stress in response to the random variable. Combined with random perturbation theory and first-order second-moment (FOSM method, the study analyzed the reliability and its sensitivity of metal structure. In conclusion, we established a novel method for accurately quantitative analysis and design of bridge crane metal structure.

  5. 南京铁心桥钢桥面热拌环氧混凝土铺装工艺研究%Hot-mixing Epoxy Asphalt Concrete Pavement Technology for Steel BridgeDeck Pavement of Tiexin Bridge in Nanjing City

    Institute of Scientific and Technical Information of China (English)

    潘军; 杨文

    2016-01-01

    Based on the steel bridge deck pavement engineering of Tiexin bridge in Nanjing city,the pavement technologies of hot mixing epoxy asphalt concrete using on steel deck were studied,inclu-ding the pavement structure design,mix design,pavement performance evaluation and construction technology.The difference of pavement construction between hot mixing and warm mixing epoxy as-phalt were also introduced in this paper.Research results show that hot mixing epoxy asphalt is suit-able for steel deck pavement due to its high stability,excellent high temperature performance and con-venient workability.%结合南京铁心桥钢桥面环氧铺装实体工程,对热拌环氧沥青混凝土铺装结构形式、热拌环氧沥青性能与混合料配合比设计、路用性能评价,以及施工工艺进行了系统研究,全面比较了热、温拌环氧沥青铺装施工工艺的区别。结果表明,热拌环氧沥青混凝土具有高强度、出色的高温稳定性,以及便捷的施工可操作性,非常适用于大跨钢桥铺装工程。

  6. Finishes for Wood Decks

    Science.gov (United States)

    Mark Knaebe

    2013-01-01

    Wood decks have become an important part of residential construction. Wood decks can add versatile living space to a home and, with minimal maintenance, provide decades of use. However, wood decks are exposed to high levels of stress from severe weather conditions that shrink and swell the wood. Without proper maintenance, wood decks can develop problems such as checks...

  7. 水泥混凝土桥梁长寿命桥面铺装层复合结构疲劳特性%Fatigue Performance of Composite Structure for Perpetual Pavement on Cement Concrete Bridge Deck

    Institute of Scientific and Technical Information of China (English)

    钱振东; 王江洋; 王亚奇

    2012-01-01

    In order concrete bridge, to design the perpetual pavement with excellent fatigue behavior for the cement based on the characteristics required for perpetual road pavement, three composite structures were tested with four-point flexural bending test to investigate fatigue properties based on the Weibull distribution theory. The double-logarithm fatigue equations for perpetual pavement were established. The results show that the fatigue lives of three composite structures follow the double-parameter Weibull distribution. With the failure probability of 0.1, the fatigue performance of composite structure, when the lower layer is AC while the lower layer uses epoxy asphalt mixture (EAM) as a substitute for stone mastic asphalt (SMA), is improved significantly. In addition, the fatigue performance of composite structure, when the lower layer is EAM while the upper layer uses SMA as a substitute for asphalt concrete (AC), is improved more. The combination structure of EAM and SMA has the best fatigue performance, and totally satisfies the structure design feature requirement for perpetual pavement. The research results provide a reliable foundation for the further study of the perpetual bridge deck pavement.%为了构建疲劳性能优异的水泥混凝土桥梁长寿命铺装结构,借鉴长寿命沥青路面设计的基本思路,选取3种铺装复合结构方案,采用应变控制的四点弯曲疲劳试验,并基于Weibull分布理论对复合结构的疲劳特性进行分析,建立长寿命桥面铺装复合结构双对数疲劳预估方程。研究结果表明:3种铺装复合结构的疲劳寿命均服从双参数Weibull分布;在失效概率为0.1时,复合结构上面层同为AC,下面层采用环氧沥青混合料(EAM)代替SMA后,其疲劳性能得到提高,复合结构下面层同为EAM,上面层采用SMA代替AC后,疲劳性能得到再次提高;"EAM+SMA"的组合具有较好的抗疲劳性能,同时满足长寿命桥面铺装的结构最优设

  8. 南京四桥钢桥面铺装防水粘结层试验及施工工艺研究%Tests for Waterproof Binding Layer of Steel Bridge Deck Pavement of Fourth Nanjing Changjiang River Bridge and the Paving Technique

    Institute of Scientific and Technical Information of China (English)

    章登精; 朱华平; 潘友强

    2014-01-01

    T he Fourth Nanjing Changjiang River Bridge is a three-span continuous steel box girder suspension bridge with a main span of 1 418 m ,to which the composite poured asphalt steel deck pavement system has been used for the first time .The lower layer of the pavement is the 4 cm thick GA-13 poured asphalt concrete w hile the upper layer is the 3 .5 cm thick AC-13 high-elastic modified asphalt concrete ,and the binding layer between the lower layer and the steel deck plate a-dopts the solvent rubber asphalt .To investigate the performance of the binding layer ,the solvent rubber asphalt was checked by the pull-out test and shear test .The results indicate that the bind-ing layer of solvent rubber asphalt can better meet the anti-debonding damage requirements of the steel bridge deck pavement under constant temperatures ,but under the extreme low temperatures , the tensile strength of the binding layer should be checked .The binding layer is proved satisfying the anti-shear requirements .To direct the binding layer construction ,the testing of the surface handling technique for the steel bridge deck and that of the field construction technique of the bind-ing layer were carried out .According to the test results ,the targeted measures taken for ensuring the construction quality were proposed . The sandblasting of the steel bridge deck was set at Sa3 .0 .After the sandblasting of the steel bridge deck ,the waterproof binding layer was directly paved and there was no need to do the traditional zinc spraying or painting protection .The rational construction control parameters were determined through experimental study and trial section con-struction .%南京四桥为主跨1418 m的三跨连续钢箱梁悬索桥,在国内首次采用复合浇注式沥青钢桥面铺装体系,下层为4 cm厚GA -13浇注式沥青混凝土,上层为3.5 cm厚AC -13高弹改性沥青混凝土,下层与桥面钢板的粘结层采用溶剂型橡胶沥青。为了解粘结层性能,

  9. Critical wind velocities for several kinds of typical vehicle running on a cable-stayed bridge deck%几种典型车辆在斜拉桥桥面行驶的临界风速研究

    Institute of Scientific and Technical Information of China (English)

    马麟; 韩万水; 刘健新; 李加武

    2011-01-01

    The critical wind velocity and running velocity were studied for three kinds of typical vehicle running on a cable-stayed bridge deck under action of strong side wind. The effects of the bridge's side buffeting and the following coordinate features of the vehicle's moving equations on the vehicle side deviation relative to the bridge deck were analyzed, the calculation formulas of its relative side slipping and velocity were obtained. Based on previous studies, a wind-vehicle-bridge coupling vibration system including vehicle side deviation and driver's behavior was studied, and the corresponding simulation code was improved and tested. A cable-stayed bridge was taken as an example, critical wind velocities of three kinds of typical automobile running on the bridge deck were obtained. Results showed that the critical wind velocity is not significantly influenced by controlling objectives of driver behavior; the accident types of different vehicles are possibly different; for box-type truck, its critical wind velocity of side slipping is always lower than that of overturning; but for cars like Santana and Jia-bao, overturning accident plays a controlling role when running velocity is high, while side slipping accident does when running velocity is low.%研究强侧风作用下三种典型汽车在斜拉桥桥面行驶时的临界风速和车速.分析汽车运动方程的随动坐标特性和桥梁的侧向抖振对汽车相对桥面侧偏的影响,得到侧偏位移及速率的计算式,在以往基础上,研究了考虑车辆侧偏和驾驶员行为的风-车-桥空间耦合振动系统,完善了仿真分析程序的功能.以某斜拉桥为实例,分析三种典型车辆在桥面行使的临界风速.分析结果表明:采用控制重心还是前轮侧滑的驾驶员模型不显著影响桥面汽车临界风速的大小;不同类型汽车的事故原因可能不同,对于箱式货车,侧滑事故起控制作用,对于桑塔纳和一汽佳宝,车速高时,侧倾

  10. Reliability Assessment for PSC Box-Girder Bridges Based on SHM Strain Measurements

    Directory of Open Access Journals (Sweden)

    Chuang Chen

    2017-01-01

    Full Text Available A reliability assessment method for prestressed concrete (PSC continuous box-girder bridges based on structural health monitoring (SHM strain measurements was proposed. First, due to the fact that measured strain was compositive and the variation periods of its components were different, a series of limit state equations under normal use limit state were given. Then, a linear fitting method was used to determine the relationship between the ambient temperature and the measured strain, which was aimed at extracting the vehicle load effect and the temperature load effect from the measured strain. Finally, according to the equivalent normalization method, the load effects unsatisfying the normal distribution by probability density function fitting were transformed, and the daily failure probabilities of monitored positions were calculated for evaluating the safety state of the girder. The results show that (1 the top plate of the box girder is more sensitive than the bottom plate to the high temperature, (2 the daily and seasonal strain variations induced by uniform temperature reveal an inconsistent tendency to the seasonal variation for mid-span cross sections, and (3 the generalized extreme value distribution is recommended for temperature gradient stress and vehicle induced stress fitting for box-girder bridges.

  11. A-DECK Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The technical objectives of A-DECK are: 1)Flight Weight including rideshare payloads will be less than 500 Kg. 2)First fundamental frequency of integrated A-DECK...

  12. 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

  13. Reliability Design and Electro-Thermal-Optical Simulation of Bridge-Style Infrared Thermal Emitters

    Directory of Open Access Journals (Sweden)

    Peng Zhou

    2016-09-01

    Full Text Available Designs and simulations of silicon-based micro-electromechanical systems (MEMS infrared (IR thermal emitters for gas sensing application are presented. The IR thermal emitter is designed as a bridge-style hotplate (BSH structure suspended on a silicon frame for realizing a good thermal isolation between hotplate and frame. For investigating the reliability of BSH structure, three kinds of fillet structures were designed in the contact corner between hotplate and frame. A 3-dimensional finite element method (3D-FEM is used to investigate the electro-thermal, thermal-mechanical, and thermal-optical properties of BSH IR emitter using software COMSOLTM (COMSOL 4.3b, COMSOL Inc., Stockholm, Sweden. The simulation results show that the BSH with oval fillet has the lowest stress distribution and smoothest flows of stress streamlines, while the BSH with square fillet has the highest temperature and stress distribution. The thermal-optical and thermal-response simulations further indicate that the BSH with oval fillet is the optimal design for a reliable IR thermal emitter in spite of having slight inadequacies in emission intensity and modulation bandwidth in comparison with other two structures.

  14. Grey Target Optimization of Waterproof Adhesive Material for Concrete Bridge Deck Pavement Based on Mechanical Analysis%基于力学分析的桥面铺装防水粘结层材料灰靶优选

    Institute of Scientific and Technical Information of China (English)

    于新; 李英涛; 刘云

    2012-01-01

    为了优选与混凝土箱梁桥防水粘结层实际受力状态相匹配的材料,以沪杭高速公路拓宽改建工程高架桥为例,采用有限元法建立了全桥模型,在分析刹车、超载、随机动荷载等因素对防水粘结层力学响应的基础上,利用灰靶理论优选室内实测典型防水粘结层的相关技术参数.研究结果表明:刹车超载使防水粘结层产生的剪应力大于由桥面不平度引起的防水粘结层剪应力,最大可达0.397 MPa;橡胶沥青和SBS改性沥青防水粘结层综合性能较优,可作为混凝土桥防水粘结层材料.%In order to select the optimal waterproof adhesive material that meets the stress needs of concrete box girder bridge deck pavement, taking the viaduct in widening project of the Shanghai-Hangzhou Expressway as an example, a composite structure model of the whole bridge was established using the finite element method, and the influence of braking, overloading, random dynamic loading on the mechanical response of the waterproof adhesive layer was analyzed. The technique parameters of some typical materials for waterproof adhesive layer were tested in lab, and then analyzed by the grey target theory. The result shows that braking plus overloading has a larger effect on the shear stress of adhesive layer than the random dynamic loading caused by bridge deck roughness, and may produce a maximum shear stress of 0. 397 MPa. The rubber asphalt and SBS modified asphalt both have good performance, and can be used as the material of waterproof adhesive layer.

  15. Fatigue Analysis of Details in Steel Deck of Cable Stayed Bridges%斜拉桥钢桥面板细节疲劳分析

    Institute of Scientific and Technical Information of China (English)

    颜飞; 陈惟珍

    2012-01-01

    正交异性钢桥面板存在大量焊接疲劳薄弱坏节,活载反复作用下容易发生疲劳破坏,国内外针对钢桥面板的力学性能及细节疲劳研究主要考虑第二结构体系效应,通过混合有限元方法模拟斜拉桥第一结构体系效应对疲劳应力的影响,以全梁段板壳单元代替相应位置的鱼骨主梁,采用蒙特·卡洛方法模拟车流,加载于疲劳细节的应力影响面,选用Eurocode疲劳曲线验算各疲劳细节的累积损伤,结果表明受压梁段由于第一体系效应影响可不进行疲劳验算,而对受拉梁段钢桥面系进行疲劳评估时可以忽略全桥结构体系效应的影响.%There are a large number of welded fatigue weak points in steel deck which are prone to fatigue damage under cyclic loads. The second structural system effect has been mainly considered in domestic and international study of the mechanical properties and details fatigue of steel deck. The first structural system effect of fatigue stresses by replacing the corresponding position of fish bone beams with whole shell element through hybrid finite element method;and choosing the fatigue curve of Eurocode to calculate the cumulative damage of fatigue details. The results show that compression beam segment is no need for fatigue checking;while the effect of whole structural system can be ignored in fatigue assessment of tesion beam segment of steel deck.

  16. 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。

  17. Design of Experimental Suspended Footbridge with Deck Made of UHPC

    Directory of Open Access Journals (Sweden)

    Blank Marek

    2016-01-01

    Full Text Available This paper deals with the static and dynamic design of experimental footbridge for pedestrians and cyclists in the municipality Lužec nad Vltavou in Czech Republic, Europe. This work aims to familiarize the reader with calculations carried out and the results obtained, describing the static and dynamic properties of proposed footbridge. The construction of footbridge is designed as a suspended 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 tons. 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. The utilization of the excellent properties of UHPC allows to design a very thin and lightweight construction of the deck, which could not be achieved with the use of normal concrete.

  18. 正交异性钢桥面铺装有限元模拟和优化分析%Finite element simulation and optimal analysis of surfacing on steel orthotropic bridge deck

    Institute of Scientific and Technical Information of China (English)

    谭积青; 徐伟; 张肖宁

    2006-01-01

    为了确定正交异性钢桥面铺装受力状态并为设计提供参考,运用子模型有限元法分析了桥梁整体变形及局部轮载作用下铺装内部受力状态及应变分布特点.为优化设计铺装层结构,分析了铺装层模量对其应变状态影响.分析结果表明:大跨径钢桥整桥变形对铺装层受力状态影响很小,铜桥面铺装设计的控制受力因素是轮载局部作用下铺装层的横向应变,铺装层模量对铺装层的受力状态有显著影响,通过提高铺装层刚度过渡层的结构优化设计措施可以显著改善铺装层的受力状态,降低铺装层的应变水平.分别对环氧沥青混凝土、SBS改性沥青SMA和Rosphalt改性沥青混凝土的模量及疲劳性能进行了试验评价,可以为桥面铺装结构组合设计提供参考数据.%To analyze the stress state of steel orthotropic deck pavement and provide reference for the design of the overlay, the inner stress state and strain distribution of surfacing under the load of the deformation of the whole bridge structure and tyre load are analyzed by the finite element method of submodeling. Influence of surfacing modulus on the strain state of the overlay is analyzed for the purpose of the optimal design of the overlay structure. Analysis results show that the deformation of the whole bridge structure has no evident influence on the stress state of the overlay. The key factor of the overlay design is the transverse tensile strain in the overlay above the upper edge of web plate of rib. The stress state of the overlay is influenced evidently by the modulus of rigidity transform overlay. And the stress state of the overlay can be optimized and lowered by increasing the modulus and thickness of rigidity transform overlay. The fatigue test has been done to evaluate the fatigue performance and modulus of different deck pavement materials such as epoxy asphalt, SBS modified asphalt, rosphalt asphalt which can provide reference for

  19. 带有挑臂的双层钢桁悬索桥颤振性能风洞试验%Wind tunnel test for flutter stability of double-deck truss girder suspension bridge with cantilever beam

    Institute of Scientific and Technical Information of China (English)

    向活跃; 李永乐; 武兵

    2014-01-01

    为了提高加劲梁的颤振性能,针对某三塔两跨公铁两用悬索桥进行了节段模型风洞试验,探讨了多种气动措施对加劲梁颤振临界风速的影响。结果显示,在三种风攻角下,常规气动措施如增加上下桥面板中央稳定板、铁路道板及检修道开槽等措施降低了加劲梁的颤振临界风速,封闭铁路挑臂并给合上桥面板上、下中央稳定板后,加劲梁在三种风攻角下的颤振性能均大幅提高,使颤振临界风速满足要求。相关结论可为类似桥梁断面的颤振优化提供借鉴。%To improve the flutter stability of stiffened girder, the sectional model wind tunnel tests of a long span highway-railway suspension bridge with two main spans and three towers were carried out. A variety of aerodynamic measures on the flutter stability were explored. The results indicate that conventional aerodynamic measures such as the upper and lower central stabilizer, slotting rail road board and railway maintenance road reduce the critical flutter wind speed in three attack angle cases, while the flutter stability is increased significantly after closing the railway cantilever and u-sing the upper and lower central stabilizer in upper deck, which meets the requirement of standard. The conclusions can provide some references for similar bridge cross-section in the optimization of flutter stability.

  20. Force-based and displacement-based reliability assessment approaches for highway bridges under multiple hazard actions

    Directory of Open Access Journals (Sweden)

    Chao Huang

    2015-08-01

    Full Text Available The strength limit state of American Association of State Highway and Transportation Officials (AASHTO Load and Resistance Factor Design (LRFD Bridge Design Specifications is developed based on the failure probabilities of the combination of non-extreme loads. The proposed design limit state equation (DLSE has been fully calibrated for dead load and live load by using the reliability-based approach. On the other hand, most of DLSEs in other limit states, including the extreme events Ⅰ and Ⅱ, have not been developed and calibrated though taking certain probability-based concepts into account. This paper presents an assessment procedure of highway bridge reliabilities under the limit state of extreme event Ⅰ, i. e., the combination of dead load, live load and earthquake load. A force-based approach and a displacement-based approach are proposed and implemented on a set of nine simplified bridge models. Results show that the displacement-based approach comes up with more convergent and accurate reliabilities for selected models, which can be applied to other hazards.

  1. A software prototype for assessing the reliability of a concrete bridge superstructure subjected to chloride-induced reinforcement corrosion

    DEFF Research Database (Denmark)

    Schneider, Ronald; Thöns, Sebastian; Fischer, Johannes

    2014-01-01

    A software prototype is developed for assessing and updating the reliability of single-cell prestressed concrete box girders subjected to chloride-induced reinforcement corrosion. The underlying system model consists of two integrated sub-models: a condition model for predicting the deterioration...... through Bayesian updating on the basis of the DBN model. To demonstrate the effect of partial inspections, the software prototype is applied to a case study of a typical highway bridge with six spans. The case study illustrates that it is possible to infer the condition of uninspected parts...... state of the box girder and a structural model for evaluating the overall system reliability. The condition model is based on a dynamic Bayesian network (DBN) model which considers the spatial variation of the corrosion process. Inspection data are included in the calculation of the system reliability...

  2. 纵坡弯道桥面沥青铺装结构剪应力分析%Shear Stress Analysis of Bridge Deck Asphalt Pavement for Longitudinal Slope Curve

    Institute of Scientific and Technical Information of China (English)

    祁文洋; 孔晨光; 于增义

    2014-01-01

    依据纵坡弯道车辆荷载作用特性,建立纵坡弯道桥面铺装结构三维有限元模型,分析车辆载重、行驶速度、弯道半径、纵坡坡度、沥青铺装层厚度与模量对水平剪应力的影响。结果表明:设计时避免最小半径极限值与纵坡坡度最大值同时出现,适当增大沥青铺装上层模量、铺装层总厚度、减小沥青铺装下层模量,并严格控制纵坡弯道上车速及车辆载重,可减少沥青铺装层发生推移病害的可能性。%Based on the properties of vehicle loads on longitudinal slope and curved sections, this paper establish-es the 3D finite element model for the bridge deck pavement, analyzing effects of the vehicle loads, running speed, the radius of curved sections, longitudinal slope degree, the thickness and modulus of asphalt layer on horizontal shear stress. Results show that in order to avoid the appearance of the minimum radius and the maximum longitudi-nal slope degree at the same time, it is advisable to increase modulus of upper asphalt layer and the total thickness of asphalt layer, decrease sub-layer modulus, and limit the vehicle speed and load at the curved sections so that translation diseases of asphalt layer can be reduced.

  3. Fatigue performance of welded aluminum deck structures

    Energy Technology Data Exchange (ETDEWEB)

    Haagensen, P.J.; Ranes, M.; Kluken, A.O.; Kvale, I.

    1996-12-01

    Aluminum alloys are used increasingly in load carrying structures where low weight and low maintenance costs are at a premium. Helicopter decks, structures for living quarters and personnel transfer bridges between platforms are examples of offshore applications. While these structures are not usually subjected to high fatigue loads, the increasing use of aluminum in high speed ships, and more recently in highway bridge structures, makes the question of fatigue performance more important. In this paper the fatigue properties of small scale weldments in an AA6005 alloy are compared with the results of fatigue tests on full scale sections of welded extrusions in the same material, which were used in an aluminum bridge deck structure. The fatigue performance is also compared with the fatigue clauses in the new British design code BS8118 for aluminium structures and the proposed Eurocode 9. The prospects of using a new joining technique, friction stir welding (FSW), in the production of large scale panels for deck and ship hull structures is discussed. The FSW process is described briefly, and some fatigue test data are presented.

  4. Combined Plate-Beam Element Method for Local Vibration Computation of Orthotropic Steel Bridge Deck%正交异性钢桥面板局部振动计算的组合板梁单元法

    Institute of Scientific and Technical Information of China (English)

    马牛静; 王荣辉

    2011-01-01

    Proposed in this paper is a combined plate-beam element method to calculate the local vibration of the orthotropic steel bridge deck with trapezoid stiffened ribs, which is used in the long-span steel bridge. In this method, the top plate and the trapezoid stiffened rib are respectively taken as the flat shell element and the plate-beam element, and the corresponding displacement model is established according to the deformation coordination relationship between the plate and the rib. Moreover, the stiffness matrix of the combined plate-beam element is obtained based on the energy-variation principle, and the consistent mass matrix and the consistent load matrix are obtained based on the shape function of each sub-element. Then, the finite dynamic equilibrium equations are obtained. Finally, a calculation program of dynamic finite element is presented for the combined plate-beam element, and the first 10 consequent natural frequencies are compared with those of the shell finite element, finding that the latters accord well with the formers. Thus, the proposed method proves to be feasible and efficient.%针对大跨度钢桥中采用梯形加劲肋的正交异性钢桥面板,提出一种计算钢桥面板局部振动的组合板梁单元法.其中顶板用平板壳单元分析,梯形加劲肋视为板梁单元,两者的位移模式根据板与肋的变形协调关系建立.组合板梁单元的刚度矩阵通过能量变分原理得到,利用各子单元的形函数可以求得组合板梁单元的一致质量矩阵与一致荷载列阵,进而得到相应的有限元动力平衡方程组.最后编制了组合板梁单元的有限元动力计算程序,将其前10阶自振频率与板壳有限元计算结果进行比较,验证了该方法的可行性与高效性.

  5. Fatigue Life Study of U-rib Butt Weld of Steel Bridge Deck%钢桥面板U肋对接焊缝疲劳寿命研究

    Institute of Scientific and Technical Information of China (English)

    王益逊; 傅中秋; 孙童; 徐捷; 朱伟

    2016-01-01

    以江阴长江大桥为研究对象,建立正交异性钢桥面板局部有限元模型,计算各种标准疲劳车作用下U肋对接焊缝处的疲劳应力幅,结合BS5400规范得到该细节相应位置的疲劳损伤度;建立车辆轮迹分布模型,将影响疲劳损伤的各参数矩阵化,根据实桥车流模拟结果,提出一种考虑轮迹改变的疲劳损伤计算方法。结果表明,U 肋对接焊缝腹板处的损伤相对较小,靠近顶板部位、腹板与底板交接部位,以及U肋底部的损伤较为严重;考虑车辆轮迹改变后的疲劳寿命与实测结果吻合度较高,因此考虑车辆轮迹位置的改变可以提高寿命评估的精确度。%The Jiangyin Yangtze River Bridge is studied in this paper .The local finite element model of orthotropic steel bridge deck is established .The fatigue stress amplitude of U‐rib butt weld under all kinds of standard vehicle loads is calculated and thus the fatigue damage degree of a certain position is obtained according to the specification BS5400 .Then ,the vehicle wheelmark distribution model is built up .By matrixing all parameters that affect the fatigue damage and considering w heelmark chan‐ges ,a fatigue damage calculation method is proposed based on the simulation results of traffic flow . The results show that the damage of U‐rib web butt weld is relatively less while that near the roof ,of web‐floor joint and of U‐rib floor is more serious .In addition ,the fatigue life of U‐rib butt weld by considering wheelmark changes matches well with the measured results .Therefore ,the accuracy of fatigue assessment could be improved by considering w heelmark changes in the calculation of fatigue lif e .

  6. Reliability Evaluation of a Single-phase H-bridge Inverter with Integrated Active Power Decoupling

    DEFF Research Database (Denmark)

    Tang, Junchaojie; Wang, Haoran; Ma, Siyuan

    2016-01-01

    it with the traditional passive DC-link solution. The converter level reliability is obtained by component level electro-thermal stress modeling, lifetime model, Weibull distribution, and Reliability Block Diagram (RBD) method. The results are demonstrated by a 2 kW single-phase inverter application....

  7. 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.

  8. Analysis of an Orthotropic Deck Stiffened with a Cement-Based Overlay

    DEFF Research Database (Denmark)

    Walter, Rasmus; Olesen, John Forbes; Stang, Henrik

    2007-01-01

    Over the past years, with increasing traffic volumes and higher wheel loads, fatigue damage in steel parts of typical orthotropic steel bridge decks has been experienced on heavily trafficked routes. A demand exists to find a durable system to increase the fatigue safety of orthotropic steel bridge...... decks. A solution might be to enhance the stiffness of the traditional orthotropic bridge deck by using a cement-based overlay. In this paper, an orthotropic steel bridge deck stiffened with a cement-based overlay is analyzed. The analysis is based on nonlinear fracture mechanics, and utilizes...... of crack widths. Furthermore, the analysis shows that debonding is initiated for a certain crack width in the overlay. The load level where cracking and debonding is initiated depends on the stress-crack opening relationship of the material....

  9. Fatigue life analysis of steel bridge deck based on measured strain%基于实测应变的钢桥面板疲劳寿命分析

    Institute of Scientific and Technical Information of China (English)

    吉伯海; 程苗; 傅中秋; 袁周致远

    2014-01-01

    In order to evaluate the fatigue life of a steel bridge deck, stress measuring points were set near the weld of the roof connected to the U-rib and the arc-shaped notch of the diaphragm plate across a quarter of a bridge ’ s steel box girder, and the fatigue stress was monitored for 24 hours. According to the measured data, the fatigue stress spectra were calculated with the rain-flow counting method. Based on the BS 5400 specification, the fatigue damage state of the stress measuring points was evaluated. The results show that the stress level of the measuring points near the arc-shaped notch of the diaphragm plate was relatively high. Each stress measuring point was mainly a low-rising stress cycle and the cycles of 2 to 10 Mpa stress amplitude accounted for more than 90%. However, the maximum stress amplitude exceeded the limit of fatigue damage stipulated by the BS 5400 specification. Fatigue life analysis shows that fatigue cracks in the weld of the roof connected to the U-rib easily occurred near the roof area at the welding hole, and the fatigue life of the weld of the diaphragm plate connected to the U-rib’ s web was short.%为评估钢桥面板的疲劳寿命,在某大桥钢箱梁1/4跨截面的顶板与U肋连接焊缝处和横隔板弧形缺口处布置应力测点,进行24 h疲劳应力监测。根据实测数据,利用雨流计数法计算得到疲劳应力谱,并基于BS 5400规范对各应力测点的疲劳损伤状态进行评估。结果表明:横隔板弧形缺口周边测点的应力水平相对较高;各应力测试点以低幅值应力循环为主,其中应力幅为2~10 MPa的循环次数占90%以上,但最大应力幅值均超过了BS 5400规范规定的产生疲劳损伤的极限值。疲劳寿命分析表明,顶板与U肋纵向连接焊缝过焊孔处易产生靠近顶板部位的疲劳裂纹,横隔板与U肋腹板连接焊缝的疲劳寿命较低。

  10. Fatigue influence for wheels position of the orthotropic steel bridge deck of U-rib butt weld%轮迹位置对钢桥面板U肋对接焊缝疲劳性能的影响

    Institute of Scientific and Technical Information of China (English)

    朱伟; 吉伯海; 傅中秋

    2015-01-01

    为研究车轮行驶位置对钢桥面板U肋对接焊缝疲劳性能的影响,现以江阴长江大桥为研究对象,采用数值模拟的方法,计算了不同车辆轮迹位置作用下U肋对接焊缝处的疲劳应力幅,结合BS5400规范得到了该细节相应位置的疲劳损伤度;建立U肋对接焊缝局部模型,模拟了不同车轮位置作用下疲劳裂纹扩展路径,同时得到了各扩展阶段的裂纹扩展参数。结果表明:车轮位置与焊缝之间距离大于600 mm,可忽略车辆位置对U肋对接焊缝开裂前的疲劳损伤累计;相对于其他部位,U 肋两侧弧形段疲劳损伤严重,易产生疲劳裂纹;随着车轮位置的改变,裂纹扩展路径逐渐由与焊缝平行向与焊缝垂直发展,车轮位置与焊缝之间距离大于750 mm,可忽略车辆位置对U肋对接焊缝开裂后的裂纹扩展影响。%In order to study the fatigue effect of the orthotropic steel bridge deck of U-rib butt weld under different wheels position, which use the numerical simulation method and as the Jiangyin Yangtze River Bridge for research object. First use the general-purpose finite element software to analysis the fatigue stress amplitude of U-rib butt welds under different wheels position, which com-bined with BS5400 standard to calculate the degree of fatigue damage for this fatigue details, and then use FRANC2 D/L software to simulate the changing rules of crack propagation path under differ-ent wheels positions. The results show that: the distance of wheels and U-rib is greater than 600 mm, it can ignore the fatigue damage cumulative to butt weld; compared to other sites, the fatigue damage of the sides of U-rib arc-shaped segment is serious, which easy to produce fatigue crack;with the change of the position of the wheels, the crack propagation path change from parallel to the butt weld to the vertical to the butt weld gradually, and while the distance of wheels and U-rib is greater than 750mm, the effect of

  11. Soil on Phoenix Deck

    Science.gov (United States)

    2008-01-01

    This image, taken by the Surface Stereo Imager (SSI) of NASA's Phoenix Lander, shows Martian soil piled on top of the spacecraft's deck and some of its instruments. Visible in the upper-left portion of the image are several wet chemistry cells of the lander's Microscopy, Electrochemistry, and Conductivity Analyzer (MECA). The instrument on the lower right of the image is the Thermal and Evolved-Gas Analyzer. The excess sample delivered to the MECA's sample stage can be seen on the deck in the lower left portion of the image. This image was taken on Martian day, or sol, 142, on Saturday, Oct. 19, 2008. Phoenix landed on Mars' northern plains on May 25, 2008. The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  12. Bridging Human Reliability Analysis and Psychology, Part 2: A Cognitive Framework to Support HRA

    Energy Technology Data Exchange (ETDEWEB)

    April M. Whaley; Stacey M. L. Hendrickson; Ronald L. Boring; Jing Xing

    2012-06-01

    This is the second of two papers that discuss the literature review conducted as part of the U.S. Nuclear Regulatory Commission (NRC) effort to develop a hybrid human reliability analysis (HRA) method in response to Staff Requirements Memorandum (SRM) SRM-M061020. This review was conducted with the goal of strengthening the technical basis within psychology, cognitive science and human factors for the hybrid HRA method being proposed. An overview of the literature review approach and high-level structure is provided in the first paper, whereas this paper presents the results of the review. The psychological literature review encompassed research spanning the entirety of human cognition and performance, and consequently produced an extensive list of psychological processes, mechanisms, and factors that contribute to human performance. To make sense of this large amount of information, the results of the literature review were organized into a cognitive framework that identifies causes of failure of macrocognition in humans, and connects those proximate causes to psychological mechanisms and performance influencing factors (PIFs) that can lead to the failure. This cognitive framework can serve as a tool to inform HRA. Beyond this, however, the cognitive framework has the potential to also support addressing human performance issues identified in Human Factors applications.

  13. Designing Flight Deck Procedures

    Science.gov (United States)

    Degani, Asaf; Wiener, Earl

    2005-01-01

    Three reports address the design of flight-deck procedures and various aspects of human interaction with cockpit systems that have direct impact on flight safety. One report, On the Typography of Flight- Deck Documentation, discusses basic research about typography and the kind of information needed by designers of flight deck documentation. Flight crews reading poorly designed documentation may easily overlook a crucial item on the checklist. The report surveys and summarizes the available literature regarding the design and typographical aspects of printed material. It focuses on typographical factors such as proper typefaces, character height, use of lower- and upper-case characters, line length, and spacing. Graphical aspects such as layout, color coding, fonts, and character contrast are discussed; and several cockpit conditions such as lighting levels and glare are addressed, as well as usage factors such as angular alignment, paper quality, and colors. Most of the insights and recommendations discussed in this report are transferable to paperless cockpit systems of the future and computer-based procedure displays (e.g., "electronic flight bag") in aerospace systems and similar systems that are used in other industries such as medical, nuclear systems, maritime operations, and military systems.

  14. Bridging Human Reliability Analysis and Psychology, Part 1: The Psychological Literature Review for the IDHEAS Method

    Energy Technology Data Exchange (ETDEWEB)

    April M. Whaley; Stacey M. L. Hendrickson; Ronald L. Boring; Jeffrey C. Joe; Katya L. Le Blanc; Jing Xing

    2012-06-01

    In response to Staff Requirements Memorandum (SRM) SRM-M061020, the U.S. Nuclear Regulatory Commission (NRC) is sponsoring work to update the technical basis underlying human reliability analysis (HRA) in an effort to improve the robustness of HRA. The ultimate goal of this work is to develop a hybrid of existing methods addressing limitations of current HRA models and in particular issues related to intra- and inter-method variabilities and results. This hybrid method is now known as the Integrated Decision-tree Human Event Analysis System (IDHEAS). Existing HRA methods have looked at elements of the psychological literature, but there has not previously been a systematic attempt to translate the complete span of cognition from perception to action into mechanisms that can inform HRA. Therefore, a first step of this effort was to perform a literature search of psychology, cognition, behavioral science, teamwork, and operating performance to incorporate current understanding of human performance in operating environments, thus affording an improved technical foundation for HRA. However, this literature review went one step further by mining the literature findings to establish causal relationships and explicit links between the different types of human failures, performance drivers and associated performance measures ultimately used for quantification. This is the first of two papers that detail the literature review (paper 1) and its product (paper 2). This paper describes the literature review and the high-level architecture used to organize the literature review, and the second paper (Whaley, Hendrickson, Boring, & Xing, these proceedings) describes the resultant cognitive framework.

  15. 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...

  16. Technology for long cable erection of a thousand-meter scale cable-stayed bridge

    Institute of Scientific and Technical Information of China (English)

    Rao Huarong; Deng Huibin

    2009-01-01

    In the background of the construction of Sutong Yangtze River Bridge (short as Sutong Bridge), the cable construction method and techniques of a thousand-meter scale cable-stayed bridge are introduced. Some key construction techniques, such as outspreading cable on deck, installing cable at pylon, pulling and fixing cable at the attachment with decks and cable PE sheath protection are discussed.

  17. 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...

  18. Study on Scheme Selection of Waterproof System of Bridge Deck Pavement Based on Fuzzy Evaluation Theory%模糊评价理论在桥面铺装防水体系方案比选中的应用研究

    Institute of Scientific and Technical Information of China (English)

    孙强; 潘红伟; 付建村; 孙杰

    2014-01-01

    结合华北地区某大型水泥混凝土桥面沥青铺装层工程,将半结构多目标模糊优选评价理论应用到桥面铺装防水体系方案比选中。根据桥面铺装防水体系需要综合考虑的几个方面,建立综合评价指标体系,通过确定各指标对分系统相对优属度矩阵及分系统对总决策的相对优属度向量,并确定出各方案对总决策的优越度,最终比选出方案1(热 SBS 改性沥青与0.5%单粒径预拌碎石封层+2 cm 沥青胶砂防水层+改性乳化沥青粘层)为最优方案。%Relying on bridge deck pavement for a large concrete bridge in North China,the half-structural and multi-objective fuzzy optimization theory is applied.According to considering several as-pects of waterproof system of bridge deck pavement,comprehensive evaluation index system is estab-lished.Through determining the relative subordinate degree matrix for the criteria and the relative subor-dinate degree vector of the sub-system to total decision,the preponderance of the scenarios chosen to the total decision are decided,and finally program 1 that is seal coat of heat SBS modified asphalt and 0.5%single particle size premixed gravel +waterproof layer of 2 cm asphalt sand +sticky layer of modified e-mulsified asphalt is selected as the optimal scheme.

  19. Nondestructive evaluation inspection of the Arlington Memorial Bridge using a robotic assisted bridge inspection tool (RABIT)

    Science.gov (United States)

    Gucunski, Nenad; Boone, Shane D.; Zobel, Rob; Ghasemi, Hamid; Parvardeh, Hooman; Kee, Seong-Hoon

    2014-04-01

    The information presented in this report provides a detailed assessment of the condition of the Arlington Memorial Bridge (AMB) deck. The field-data collection was obtained by both the RABIT™ Bridge Inspection Tool and a number of semi-automated non-destructive evaluation (NDE) tools. The deployment of the semi-automated NDE tools was performed to inspect the AMB deck condition and also to validate data obtained by the RABIT™ Bridge Inspection Tool. Data mining and analysis were accomplished through enhanced data interpretation and visualization capabilities using advanced data integration, fusion, and 2D rendering. One of the major challenges that the research team had to overcome in assessing the condition of the AMB deck was the presence of an asphalt overlay on the entire bridge deck.

  20. Study on Deck Runoff Collection System of Long-Span Bridges across Ecology Water Area%跨敏感水域特大桥桥面径流收集系统方案研究

    Institute of Scientific and Technical Information of China (English)

    彭晓彬

    2015-01-01

    本文在调研危化品运输车辆和初期雨水污染物浓度分析的基础上,给出了危化品泄漏量、初期雨水径流量、设计降雨历时等主要参数的确定方法;基于雨水管道极限强度理论,提出了包含纵向截流管及收集池的桥面径流收集系统设计方法;并结合实际工程设计,对多种桥面径流收集及处理方案进行了分析比较,提出了相关建议,从而为今后的特大桥桥面径流收集系统研究起参考和借鉴的作用。%Based on the investigation of dangerous chemicals transport vehicles and the analysis of initial rainwater pollutant concentrations,the determination methods were given for some main parameters,such as leakage rate of dangerous chemicals,initial rainwater runoff discharge,design rainfall duration and so on.based on the ultimate strength theory of rainwater pipelines,the design method for deck runoff collection system was proposed.some schemes for deck runoff collection and treatment were analyzed and compared based on actual projects.And some suggestions were proposed in hope of sheding light on future research and design in this field.

  1. Bridge Pressure Flow Scour at Clear Water Threshold Condition

    Institute of Scientific and Technical Information of China (English)

    GUO Junke; KERENYI Kornel; PAGAN-ORTIZ Jorge E; FLORA Kevin

    2009-01-01

    Bridge pressure flow scour at clear water threshold condition is studied theoretically and experimentally. The flume experiments reveal that the measured scour profiles under a bridge are more or less 2-dimensional; all the measured scour profiles can be described by two similarity equations, where the horizontal distance is scaled by the deck width while the local scour by the maximum scour depth; the maximum scour position is located just under the bridge about 15% deck width from the downstream deck edge; the scour begins at about one deck width upstream the bridge while the deposition occurs at about 2.5 deck widths downstream the bridge; and the maximum scour depth decreases with increas-ing sediment size, but increases with deck inundation. The theoretical analysis shows that: bridge scour can be divided into three cases, i.e. downstream unsubmerged, partially submerged, and totally submerged. For downstream unsubmerged flows, the maximum bridge scour depth is an open-channel problem where the conventional methods in terms of critical velocity or bed shear stress can be applied; for partially and totally submerged flows, the equilibrium maximum scour depth can be described by a scour and an inundation similarity number, which has been confirmed by experiments with two decks and two sediment sizes. For application, a design and field evaluation procedure with examples is presented, including the maximum scour depth and scour profile.

  2. Seafloor Surficial Sediments (Deck 41)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The National Geophysical Data Center (NGDC) "Deck41" database contains surficial sediment descriptions for over 36,000 seafloor samples worldwide. The file was begun...

  3. Towards multiple hazard resilient bridges: a methodology for modeling frequent and infrequent time-varying loads Part I, Comprehensive reliability and partial failure probabilities

    Science.gov (United States)

    Liang, Zach; Lee, George C.

    2012-09-01

    The current AASHTO load and resistance factor design (LRFD) guidelines are formulated based on bridge reliability, which interprets traditional design safety factors into more rigorously deduced factors based on the theory of probability. This is a major advancement in bridge design specifications. However, LRFD is only calibrated for dead and live loads. In cases when extreme loads are significant, they need to be individually assessed. Combining regular loads with extreme loads has been a major challenge, mainly because the extreme loads are time variables and cannot be directly combined with time invariant loads to formulate the probability of structural failure. To overcome these difficulties, this paper suggests a methodology of comprehensive reliability, by introducing the concept of partial failure probability to separate the loads so that each individual load combination under a certain condition can be approximated as time invariant. Based on these conditions, the extreme loads (also referred to as multiple hazard or MH loads) can be broken down into single effects. In Part II of this paper, a further breakdown of these conditional occurrence probabilities into pure conditions is discussed by using a live truck and earthquake loads on a bridge as an example. There are three major steps in establishing load factors from MH load distributions: (1) formulate the failure probabilities; (2) normalize various load distributions; and (3) establish design limit state equations. This paper describes the formulation of the failure probabilities of single and combined loads.

  4. Similarities and differences in bare concrete deck deterioration curves from multi NDE technology surveys

    Science.gov (United States)

    Kim, Jinyoung; Gucunski, Nenad; Dinh, Kien

    2016-04-01

    Reinforced concrete decks are in most cases the fastest deteriorating components of a bridge due to the multitude of influencing factors: direct traffic loading and environmental effects, maintenance activities (salting), etc. Among many deterioration types, corrosion-induced deterioration is the most common problem in reinforced concrete decks. The study concentrates on the condition assessment of bridge decks using complementary NDE techniques. The assessment has three main components: assessment of corrosive environment and corrosion processes, and assessment with respect to the deck delamination. The study concentrates on a complementary use of five NDE techniques: impact echo (IE) to detect and characterize delamination, ground penetrating radar (GPR) to describe the corrosive environment and detect delamination, and electrical resistivity (ER) to estimate the corrosion rate by measuring concrete resistivity. The ability of the NDE methods to objectively characterize deterioration progression is illustrated by the results from NDE surveys of 10 bridges of different ages in New Jersey during a period of one year. The deterioration progression is illustrated by condition maps and condition indices. As demonstrated in the paper, multiple deterioration models are developed utilizing the proposed methodology, which shows high potential for development of more realistic deterioration and life cycle cost models for bridge decks.

  5. 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)....

  6. Seismic Retrofitting of an Existing Steel Railway Bridge by Fluid Viscous Dampers

    Science.gov (United States)

    Gangopadhyay, Avijit; Ghosh, Aparna Dey

    2016-06-01

    There are over a lakh of bridges in the Indian Railways, many of which have become seismically deficient, either through aging or due to inadequate seismic design considerations. The extensive damage of bridges all over the world in recent earthquakes has propelled significant advancement in earthquake protection and retrofitting of bridges. Amongst various passive control systems that are reliable as well as cost-effective, Fluid Viscous Dampers (FVDs) are proving to be successful in bridge vibration control. Orificed FVDs, commercially available as Taylor Devices, have already been successfully installed in several bridges worldwide. However, there has been no such application or study related to Indian railway bridges. In this paper, an existing thirty years' old railway bridge in Jharkhand, India, has been analyzed in SAP2000v14 considering reduced stiffness and found deficient when subjected to spectrum-compatible accelerograms. Subsequent retrofitting of the bridge superstructure with FVDs has been carried out and the results indicate substantial reductions in the responses of the bridge deck.

  7. Seismic Retrofitting of an Existing Steel Railway Bridge by Fluid Viscous Dampers

    Science.gov (United States)

    Gangopadhyay, Avijit; Ghosh, Aparna Dey

    2016-09-01

    There are over a lakh of bridges in the Indian Railways, many of which have become seismically deficient, either through aging or due to inadequate seismic design considerations. The extensive damage of bridges all over the world in recent earthquakes has propelled significant advancement in earthquake protection and retrofitting of bridges. Amongst various passive control systems that are reliable as well as cost-effective, Fluid Viscous Dampers (FVDs) are proving to be successful in bridge vibration control. Orificed FVDs, commercially available as Taylor Devices, have already been successfully installed in several bridges worldwide. However, there has been no such application or study related to Indian railway bridges. In this paper, an existing thirty years' old railway bridge in Jharkhand, India, has been analyzed in SAP2000v14 considering reduced stiffness and found deficient when subjected to spectrum-compatible accelerograms. Subsequent retrofitting of the bridge superstructure with FVDs has been carried out and the results indicate substantial reductions in the responses of the bridge deck.

  8. 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.

  9. On the typography of flight-deck documentation

    Science.gov (United States)

    Degani, Asaf

    1992-01-01

    Many types of paper documentation are employed on the flight-deck. They range from a simple checklist card to a bulky Aircraft Flight Manual (AFM). Some of these documentations have typographical and graphical deficiencies; yet, many cockpit tasks such as conducting checklists, way-point entry, limitations and performance calculations, and many more, require the use of these documents. Moreover, during emergency and abnormal situations, the flight crews' effectiveness in combating the situation is highly dependent on such documentation; accessing and reading procedures has a significant impact on flight safety. Although flight-deck documentation are an important (and sometimes critical) form of display in the modern cockpit, there is a dearth of information on how to effectively design these displays. The object of this report is to provide a summary of the available literature regarding the design and typographical aspects of printed matter. The report attempts 'to bridge' the gap between basic research about typography, and the kind of information needed by designers of flight-deck documentation. The report focuses on typographical factors such as type-faces, character height, use of lower- and upper-case characters, line length, and spacing. Some graphical aspects such as layout, color coding, fonts, and character contrast are also discussed. In addition, several aspects of cockpit reading conditions such as glare, angular alignment, and paper quality are addressed. Finally, a list of recommendations for the graphical design of flight-deck documentation is provided.

  10. Active aerodynamic stabilisation of long suspension bridges

    DEFF Research Database (Denmark)

    Nissen, Henrik Ditlev; Sørensen, Paul Haase; Jannerup, Ole Erik

    2004-01-01

    The paper describes the addition of actively controlled appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suppension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to ma...

  11. Active aerodynamic stabilisation of long suspension bridges

    DEFF Research Database (Denmark)

    Nissen, Henrik Ditlev; Sørensen, Paul Haase; Jannerup, Ole Erik

    2004-01-01

    The paper describes the addition of actively controlled appendages (flaps) attached along the length of the bridge deck to dampen wind-induced oscillations in long suppension bridges. A novel approach using control systems methods for the analysis of dynamic stability is presented. In order to ma...

  12. 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...

  13. Experiment study on fatigue behavior of composite girders with steel plate-concrete composite bridge decks%带钢板-混凝土组合桥面板的组合梁疲劳性能试验研究

    Institute of Scientific and Technical Information of China (English)

    杨勇; 周现伟; 薛建阳; 霍旭东

    2012-01-01

    In order to study the fatigue behaviour of the steel plate-concrete composite-deck composite girders under the fatigue load, constant-amplitude fatigue tests of six specimens of the steel plate-concrete composite-deck composite beam were carried out and static loading experiments of two specimens were conducted. The influence of the main factors including the upper and lower limits of fatigue load and the stress amplitude on the failure modes and the fatigue damage extent of composite girders under fatigue load were focused on. The dynamic deflection, strains of concrete and steel plates, strains of steel beam, residual deflection and residual bearing capacity were measured and analyzed. From the tests results, the fatigue life-spans of the composite girders specimens were directly related with their stress amplitudes, but the upper and lower limits of fatigue load had little effect. With regard to the fatigue failure modes of the composite girders specimens, positive moment composite girders were all failed due to collapse of the steel beam and crush of concrete of compressive zone, but not to the negative moment of composite girders, as a result of steel-beam buckling under static tests after fatigue tests. This paper were very helpful for this type of compsite girders design.%为研究带钢板-混凝土组合桥面板的组合梁在疲劳荷载下的受力性能,对2个试件进行静力试验研究,并对6个试件进行等幅疲劳试验研究。疲劳试验试件按承受正弯矩和承受负弯矩两组类型试件分别考虑,在各组试件中均主要考察疲劳荷载上、下限值及疲劳荷载幅值等因素对带钢板-混凝土组合桥面板组合梁的疲劳破坏模式及疲劳累积损伤的影响。疲劳试验过程中对组合梁试件在各主要循环加载次数下的动挠度、残余挠度、混凝土应变、底部钢板应变、试件钢梁应变及试件受弯刚度进行试验测量和分析。疲劳试验结果表明:正

  14. Parametric modelling of nonstationary platform deck motions

    Digital Repository Service at National Institute of Oceanography (India)

    Mandal, S.

    -sense-stationary processes. Then the time series are modelled by the maximum entropy method which is formulated here for spectral estimation of platform deck displacements. The lower order maximum entropy spectra of nonstationary platform deck displacements are compared...

  15. Two-stage Hemodialysis Reliable Outflow (HeRO) graft implantation technique that avoids the use of a femoral bridging dialysis catheter.

    Science.gov (United States)

    Yoon, William J; Lorelli, David R

    2015-01-01

    The purpose of this study is to report a novel two-stage Hemodialysis Reliable Outflow (HeRO) graft implantation technique that avoids the use of a femoral bridging hemodialysis catheter in internal jugular vein (IJV) catheter-dependent patients with contralateral central venous occlusion. The first stage is to implant the ePTFE component and consists of: 1) performing two to three incisions in the upper arm ipsilateral to the preexisting IJV catheter, 2) tunneling the expanded polytetrafluoroethylene (ePTFE) component through these incision sites, and 3) placing the ePTFE component in the subcutaneous tissue without anastomosing it to the target artery. The preexisting IJV catheter is maintained to provide continuous dialysis access. The second stage is initiated in 4 weeks and includes: 1) thrombectomy and anastomosing the ePTFE component arterial end to the target artery, 2) insertion of the venous outflow component using the preexisting IJV catheter access site, and 3) connecting the venous outflow component to the ePTFE component in the standard fashion. The HeRO graft was successfully implanted in two stages without using a femoral bridging catheter. Immediate postimplant cannulatabilty was achieved upon completion of the second stage procedure. This novel two-stage HeRO implantation technique is simple, yet allows immediate cannulation upon completion of the second stage procedure while avoiding the need of a femoral bridging catheter in IJV catheter- dependent patients with contralateral central venous occlusion, and thus lowering the risk of infection related to a femoral bridging catheter.

  16. 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. 

  17. 75 FR 4584 - Wire Decking From China

    Science.gov (United States)

    2010-01-28

    ... COMMISSION Wire Decking From China AGENCY: United States International Trade Commission. ACTION: Scheduling... retarded, by reason of subsidized and less-than-fair-value imports from China of wire decking, provided for..., producers, or exporters in China of wire decking, and that such ] products are being sold in the...

  18. IRC evaluates corrosion in repaired concrete bridge slabs

    Energy Technology Data Exchange (ETDEWEB)

    Qian, S. [National Research Council of Canada, Ottawa, ON (Canada)

    2001-03-01

    The old two-lane Perley Bridge in Hawkesbury, Ontario, has been replaced by a four-lane bridge. The old bridge had a reinforced concrete deck supported by a steel structure. A research project aimed at evaluating the corrosion present in the steel reinforcement in repaired concrete on the old bridge was completed, and the results indicated that corrosion can be predicted in a more reliable manner by using several different corrosion monitoring techniques and analyzing the results. The exposure conditions and the age of the old bridge were known, which made it possible to obtain valuable information on the deterioration process and mechanisms, as well as their effect on the corrosion of the reinforcing steel by examining the slabs. Several factors play a role in the probability and rate of corrosion. They include carbon dioxide, sulphur dioxide, nitrous oxide, and chloride present in the atmosphere, and the amounts of oxygen at the interface of the steel reinforcement and the concrete. Half-cell potential measurements, which measure the potential difference between a standard portable half-cell and the reinforcing steel, have been used since the 1980s to identify the condition of concrete structures. This measurement provides only an indication of the likelihood of corrosion. In the case of the Perley Bridge, half-cell potential measurements, linear polarization, and concrete resistivity measurements were taken on four slabs of repaired concrete removed from the bridge. The results demonstrated that each method has benefits and limitations, which used in combination, provide a valid indication of active corrosion in the reinforcement. In the future, the reliability of different techniques will be assessed by considering environmental conditions.

  19. Bending Moments Distribution at the Main Structural Elements of Skew Deck-Slab and Their Implementation on Cost Effectiveness

    Directory of Open Access Journals (Sweden)

    Maher Kakish

    2007-01-01

    Full Text Available The distribution of bending moments in T-beam deck slab varies from one T-beam to another. The design of T-beams should be based on the actual bending moments each beam is subjected to for the purpose of achieving economy especially in bridge deck slab, extended over big area. The saving in some cases is substantial due to reducing the quantities of steel and concrete.

  20. Finite Element Analysis of Composite Deck Slab Using Perfobond Rib as Shear Connection System under Vertical Loading

    Directory of Open Access Journals (Sweden)

    Omid Monshi Toussi

    2016-01-01

    Full Text Available Nowadays, the composite decks are very common to use in composite or steel construction. In this case of study the composite slabs have been investigated numerically by Finite Element Method (FEM. Five composite slabs were analyzed using finite element software LUSAS. The deflection of each model were obtained and compared with experimental test. Results showed a good agreement with the experimental data and indicate that the perfobond rib is appropriate shear connector for the bridges decks.

  1. 正交异性钢桥面板U肋对接焊缝疲劳损伤度分析∗%STUDY OF THE FATIGUE DAMAGE BEHAVIOR OF U-RIB BUTT WELDS OF ORTHOTROPIC STEEL BRIDGE DECK

    Institute of Scientific and Technical Information of China (English)

    王益逊; 吉伯海; 姚悦; 傅中秋; 朱伟

    2016-01-01

    The measuring points were set on the U⁃rib butt welds of fast lane and slow lane in a quarter⁃span of Jiangyin Yangtze River Bridge to measure the one⁃day strain process curves. The curves were filterred by MATLAB software to obtain the real strain process curves of steel box girder under the vehicle loading. The daily damage degree distribution rules of fast and slow lane were analyzed based on the rain flow method and Miner fatigue damage cumulative rule. The daily damage distribution model of U⁃rib butt welds was put forward and the fatigue life of U⁃rib butt welds was evaluated. The analysis result showed that the time when the damage peak of both kinds of lanes occurred was basically the same, yet the peak value differed a lot from each other. The peak value of the slow lane was 4. 4 times than that of the fast lane. The fitting value of fatigue life based on daily damage distribution model coincided well with that of the measured, which could be applied to practical engineerings. The design life of the bridge was superior to and 3. 7 times of the fatigue life of the U⁃rib butt in the slow lane, meaning that the fatigue life of the U⁃rib butt in the slow lane was far from demand, thus special attention should be paid to it.%分别在江阴长江大桥1/4跨截面快车道、慢车道U肋对接焊缝处布设测点,测得该桥一天的应变历程曲线。基于雨流计数法以及Miner疲劳损伤累计准则,分析快、慢车道日损伤度分布规律,并提出了该桥U肋对接焊缝部位的日损伤分布模型,最后对U肋对接焊缝处的疲劳寿命进行评估。分析结果表明,快、慢车道出现损伤峰值的时间基本一致,但各峰值大小差异性较大,慢车道损伤峰值约为快车道损伤峰值的4�4倍;根据日损伤度分布模型得出的疲劳寿命拟合值与实测值吻合良好,可以应用于实际工程;大桥设计寿命约为慢车道U肋对接焊缝实测寿命的3�7

  2. UAV Deck Recovery Stability Analysis

    Science.gov (United States)

    2012-01-01

    any point from touch-down to hangar stowage and back to launch position. Deck handling studies determine turnover limits, sliding freedom, tiedown...beam behind the LPD rack on the port side of the hangar near a fire hatch. The energy index was calculated based on the MRU’s evaluation of the...deck’s motion. Figure 18 – Motion Reference Unit (MRU) on LCS-2 The CPU is housed in a rack encased standard PC hard disk (Figure 19). Other

  3. Stability of vaccines - bridging from stability data to continuous safety and efficacy throughout shelf life - an always reliable approach?

    Science.gov (United States)

    Pfleiderer, Michael

    2009-11-01

    Stability studies are important tools to reliably ensure that efficacy and safety of medicinal products will remain unchanged from release of drug product until the end of shelf life. For complex medicinal products such as biological medicinal products, including vaccines, design and conduct of such studies requires particularly careful considerations in order to ensure that technical data resulting from stability studies are indeed indicative for unchanged clinical performance. Ideally, relevance of specifications controlled by stability studies as well as definition of shelf life should be justified by acceptable clinical data obtained with product at the end of the shelf life claimed.

  4. 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....

  5. Reliability of redundant ductile structures with uncertain system failure criteria

    Indian Academy of Sciences (India)

    Baidurya Bhattacharya; Qiang Lu; Jinquan Zhong

    2009-12-01

    Current reliability based approaches to structural design are typically element based: they commonly include uncertainties in the structural resistance, applied loads and geometric parameters, and in some cases in the idealized structural model. Nevertheless, the true measure of safety is the structural systems reliability which must consider multiple failure paths, load sharing and load redistribution after member failures, and is beyond the domain of element reliability analysis. Identification of system failure is often subjective, and a crisp definition of system failure arises naturally only in a few idealized instances equally important. We analyse the multi-girder steel highway bridge as a out of active parallel system. System failure is defined as gross inelastic deformation of the bridge deck; the subjectivity in the failure criterion is accounted for by generalizing as a random variable. Randomness in arises from a non-unique relation between number of failed girders and maximum deflection and from randomness in the definition of the failure deflection. We show how uncertain failure criteria and structural systems analyses can be decoupled. Randomness in the transverse location of trucks is considered and elastic perfectly plastic material response is assumed. The role of the system factor modifying the element-reliability based design equation to achieve a target system reliability is also demonstrated.

  6. 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.

  7. Is deck C an advantageous deck in the Iowa Gambling Task?

    Directory of Open Access Journals (Sweden)

    Lin Ching-Hung

    2007-08-01

    Full Text Available Abstract Background Dunn et al. performed a critical review identifying some problems in the Somatic Marker Hypothesis (SMH. Most of the arguments presented by Dunn focused on the insufficiencies for replication of skin conductance responses and somatic brain loops, but the study did not carefully reassess the core-task of SMH. In a related study, Lin and Chiu et al. identified a serious problem, namely the "prominent deck B phenomenon" in the original IGT. Building on this observation, Lin and Chiu also posited that deck C rather than deck A was preferred by normal decision makers due to good gain-loss frequency rather than good final-outcome. To verify this hypothesis, a modified IGT was designed that possessed high contrast of gain-loss value in each trial, with the aim of achieving a balance between decks A and C in terms of gain-loss frequency. Based on the basic assumption of IGT, participants should prefer deck C to deck A based on consideration of final-outcome. In contrast, based on the prediction of gain-loss frequency, participants should have roughly equal preferences for decks A and C. Methods This investigation recruited 48 college students (24 males and 24 females as participants. Two-stage IGT with high-contrast gain-loss value was launched to examine the deck C argument. Each participant completed the modified IGT twice and immediately afterwards was administered a questionnaire to assess their consciousness and final preferences following the game. Results The experimental results supported the predictions regarding gain-loss frequency participants choose the deck C with nearly identical frequency to deck A, despite deck C having a better final outcome than deck A. The "sunken deck C" phenomenon is clearly identified in this version of IGT which achieves a balance in gain-loss frequency. Moreover, the "sunken deck C" phenomenon not only appears during the first stage, but also during the second stage of IGT. In addition

  8. Delta-Reliability

    OpenAIRE

    Eugster, P.; Guerraoui, R.; Kouznetsov, P.

    2001-01-01

    This paper presents a new, non-binary measure of the reliability of broadcast algorithms, called Delta-Reliability. This measure quantifies the reliability of practical broadcast algorithms that, on the one hand, were devised with some form of reliability in mind, but, on the other hand, are not considered reliable according to the ``traditional'' notion of broadcast reliability [HT94]. Our specification of Delta-Reliability suggests a further step towards bridging the gap between theory and...

  9. Damage identification of RC bridge decks under fatigue loading

    Directory of Open Access Journals (Sweden)

    Zanuy, C.

    2014-12-01

    Full Text Available The complex nature of structural phenomena still requires the comparison between numerical models and the real structural performance. Accordingly, many civil structures are monitored to detect structural damage and provide updated data for numerical models. Monitoring usually relies on the change of dynamic properties (experimental modal analysis. Regarding concrete structures, existing works have typically focused on the progressive decrease of natural frequencies under gradually increasing loads. In this paper, high-cycle fatigue effects are analyzed. An experimental campaign on specimens reproducing the top slab of concrete girders has been carried out, including fatigue tests and a reference static test. Impact-excitation tests were done at different stages to extract dynamic properties. Output-only models (only based on the structural response to an external excitation that is not measured were used as identification techniques. The evolution of dynamic properties was correlated with damage development, with emphasis on the fatigue process stages: crack formation, cyclic reduction of tension-stiffening and brittle fracture of the reinforcement.La naturaleza compleja de muchos fenómenos estructurales requiere que los modelos numéricos necesiten ser verificados con el comportamiento estructural real. Por ello, muchas estructuras son monitorizadas, tanto para detectar posibles daños estructurales como para proporcionar datos a incluir en los modelos. A menudo, la monitorización se basa en el cambio de las propiedades dinámicas mediante técnicas de análisis modal experimental. Con respecto al hormigón estructural, la mayoría de los trabajos existentes se ha centrado en el cambio de las frecuencias propias con cargas monótonamente crecientes. En este artículo se analizan los efectos de la fatiga. Se ha llevado a cabo una campaña experimental sobre piezas que reproducen la losa superior de tableros de puentes, realizándose ensayos de fatiga y uno estático de referencia. Las propiedades dinámicas se han ido extrayendo mediante técnicas de output-only a partir de ensayos de excitación mediante impacto. El cambio de las propiedades dinámicas se ha correlacionado con las etapas del proceso de fatiga: formación de fisuras, reducción de tension-stiffening y rotura frágil de la armadura.

  10. Fatigue of bridges with a horizontal rotation axle under random wind load

    NARCIS (Netherlands)

    Maljaars, J.; Steenbergen, R.D.J.M.

    2012-01-01

    The operating mechanisms of movable bridges are subjected to various types of fluctuating loads which may induce fatigue damage. Wind load acting on the bridge deck - when the bridge is open - is one of the important load types. A wind load model is proposed that can be used in the fatigue design ve

  11. 夹芯钢板覆盖法(SPS)在钢箱梁桥正交异性桥面板维修加固中的应用与试验%Research on Application of Sandwich Plate System (SPS) on Strengthening Orthotropic Bridge Deck of Steel Box Girder Bridge

    Institute of Scientific and Technical Information of China (English)

    许传博; 胡利平

    2012-01-01

    This paper introduces the application of sandwich plate system SPS ) on strengthening of steel box girder bridge with load test being carried out to verify the effect of SPS, which can provide a reference for the similar engineering practice.%结合工程实例,介绍了夹芯钢板覆盖法(SPS)在钢箱梁桥维修加固中的应用,并通过荷载试验对其加固效果进行了检验,可为类似维修加固工程提供参考。

  12. A strange bridge by Leonardo

    CERN Document Server

    Huylebrouck, Dirk

    2013-01-01

    On folio 855 recto of the Codex Atlanticus, Leonardo da Vinci drew three 'easily movable' bridges, but one of them is enigmatic: all 'replicas' in Leonardo museums and exhibitions come as a surprise, to say the least, to any engineer or architect whose attention is drawn to it. This is the case for models in Amboise (France), Chicago and Portland (USA), Florence (Italy) and for the one of the traveling exhibition by the Australian company 'Grande Exhibitions' that already visited 40 major cities in the world. All 'replicas' of the bridge model attributed to Leonardo have pillars standing on the deck of the bridge, while the deck is suspended by cables attached on these pillars. At first sight this problem does not catch the attention of the observer, as the bridge seems to be a mixed form of a beam and a suspension bridge, but it was not overlooked by my colleague architect-engineer Dr. Laurens Luyten (Gent, Belgium). Yet, after a TV-interview in Brussels so much pressure was exerted by some of the museum col...

  13. Simulators for Mariner Training and Licensing: Guidelines for Deck Officer Training Systems.

    Science.gov (United States)

    1982-12-01

    34 Shiphandling and Shiphandling Training." TAEG Report Number 1. Training Analysis and Evaluation Group, Naval Training Equipment Cnter, Orlando, Florida...addresses the proper use of the shiphandling /ship bridge simulator in effectively conducting simulator training for senior commercial ship deck officers...the evaluation of simulator training courses for their personnel. Senior Mariner Simulator-Based Training SystemAO ot ? Shiphandling Instructor

  14. Full-scale measurements of dynamic response of suspension bridge subjected to environmental loads using GPS technology

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    Nowadays, there are many larger and taller engineering structures than in the past. These structures are commonly designed to be more flexible. Thus, they are sensitive to severe wind gust and earthquake tremor. For the dynamic response prediction, finite element (FE) modal updating and structural health monitoring, the dynamic characteristics of a structure are becoming increasingly important. The aim of this paper is to show an emerging tool-the real time kinematic (RTK) global positioning system (GPS), which is used to measure and monitor the low-frequency vibration of Dalian BeiDa Bridge, a medium span suspension bridge. The modal analysis is firstly performed on the developed three-dimensional FE model according to the original blue prints of the bridge to provide the analytical frequencies and mode shapes. The field ambient vibration tests using the accelerometers on the bridge deck are conducted just prior to the use of the GPS system in order to validate the FE model. And then, the calibration test is done to assess the dynamic displacement measurement accuracy of the GPS in three orthogonal directions. The GPS signal properties, such as the amplitude, standard deviations (STD), power spectral density (PSD), and probability density functions (PDF), are studied in details. After that, a structural health monitoring system based on the GPS is devised and installed on the bridge to provide real-time measurement of deck movement. The output-only modal parameter identification is carried out by using the Periodogram method to investigate the responses of the bridge. The result shows that the spectral densities of the displacements measured by the GPS correspond well with the results by the FEM analysis and the accelerometer vibration test. It is concluded that the GPS method is reliable and useful to clarify the ambient vibration response behaviors of the flexible structures. The integration of the GPS and accelerometer methods results in a hybrid arrangement

  15. Field measurement on wind characteristic and buffeting response of the Runyang Suspension Bridge during typhoon Matsa

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Field measurement on wind characteristic and buffeting response of existing bridge is of great value to the development of bridge wind engineering,and the structural health monitoring system(SHMS) em-ployed in many long-span bridges provide a research basis for the field measurement.In order to pro-vide reliable basis for wind resistant evaluation of Runyang Suspension Bridge(RSB),two anemome-ters and 85 accelerometers were installed in the SHMS of RSB.In August 2005,Typhoon Matsa crossed over Jiangsu,the SHMS timely recorded the typhoon and structural vibration responses.In this paper by using the time-frequency technique and statistical theory,the recorded data were analyzed to obtain the strong wind characteristics,the buffeting response characteristics of the cable and deck,and the variation of buffeting response RMS versus wind speed.Results obtained in this study can be em-ployed to validate the credibility of current buffeting response analysis theory techniques,and provide reference values for wind resistant evaluation of other long-span bridges.

  16. Field measurement on wind characteristic and buffeting response of the Runyang Suspension Bridge during typhoon Matsa

    Institute of Scientific and Technical Information of China (English)

    WANG Hao; LI AiQun; GUO Tong; XIE Jing

    2009-01-01

    Field measurement on wind characteristic and buffeting response of existing bridge is of great value to the development of bridge wind engineering, and the structural health monitoring system (SHMS) em-ployed in many long-span bridges provide a research basis for the field measurement. In order to pro-vide reliable basis for wind resistant evaluation of Runyang Suspension Bridge (RSB), two anemome-ters and 85 accelerometers were installed in the SliMS of RSB. In August 2005, Typhoon Matsa crossed over Jiangsu, the SHMS timely recorded the typhoon and structural vibration responses. In this paper by using the time-frequency technique and statistical theory, the recorded data were analyzed to obtain the strong wind characteristics, the buffeting response characteristics of the cable and deck, and the variation of buffeting response RMS versus wind speed. Results obtained in this study can be em-ployed to validate the credibility of current buffeting response analysis theory techniques, and provide reference values for wind resistant evaluation of other long-span bridges.

  17. Wind-Tunnel Tests of a Bridge Model with Active Vibration Control

    DEFF Research Database (Denmark)

    Hansen, H. I.; Thoft-Christensen, Palle; Mendes, P. A.

    The application of active control systems to reduce wind vibrations in bridges is a new area of research. This paper presents the results that were obtained on a set of wind tunnel tests of a bridge model equipped with active movable flaps. Based on the monitored position and motion of the deck......, the flaps are regulated by a control algorithm so that the wind forces exerted on them counteract the deck oscillations....

  18. Experimental Validation of a Numerical Model for Three-Dimensional High-Speed Railway Bridge Analysis by Comparison with a Small-Scale Model

    DEFF Research Database (Denmark)

    Sneideris, J.; Bucinskas, P.; Agapii, L.

    2015-01-01

    dimensional 10-degrees-of-freedom system. The subsoil model utilizes Green’s function for a horizontally layered half-space. The small-scale experimental model consists of bridge deck, columns and footings which are made from Plexiglas. An electric vehicle travels along the bridge deck on a track to simulate...... is based on finite-element analysis for the bridge structure and a semi-analytical solution for the subsoil. The bridge deck and columns are modelled using three-dimensional beam elements. The foundations are implemented as rigid footings placed on the ground surface. The vehicle is modelled as a two...

  19. Flight Deck I-Glasses Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Flight Deck i-Glasses is a color, stereoscopic 3-D display mounted on consumer style eye glass frames that will enhance operator performance and multi-modal...

  20. 33 CFR 155.790 - Deck lighting.

    Science.gov (United States)

    2010-07-01

    ...) POLLUTION OIL OR HAZARDOUS MATERIAL POLLUTION PREVENTION REGULATIONS FOR VESSELS Transfer Personnel... horizontal plane 3 feet above the deck the illumination must measure at least: (1) 5.0 foot candles...

  1. Deck41 Surficial Seafloor Sediment Description Database

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Deck41 is a digital summary of surficial sediment composition for 36,401 seafloor samples worldwide. Data include collecting source, ship, cruise, sample id,...

  2. COUPLING VIBRATION OF VEHICLE-BRIDGE SYSTEM

    Institute of Scientific and Technical Information of China (English)

    陈炎; 黄小清; 马友发

    2004-01-01

    By applying the sinusoidal wave mode to simulate the rugged surface of bridge deck,accounting for vehicle-bridge interaction and using Euler-Bernoulli beam theory, a coupling vibration model of vehicle-bridge system was developed. The model was solved by mode analyzing method and Runge-Kutta method, and the dynamic response and the resonance curve of the bridge were obtained. It is found that there are two resonance regions, one represents the main resonance while the other the minor resonance, in the resonance curve. The influence due to the rugged surface, the vibration mode of bridge, and the interaction between vehicle and bridge on vibration of the system were discussed. Numerical results show that the influence due to these parameters is so significant that the effect of roughness of the bridge deck and the mode shape of the bridge can't be ignored and the vehicle velocity should be kept away from the critical speed of the vehicle.

  3. Is deck B a disadvantageous deck in the Iowa Gambling Task?

    Directory of Open Access Journals (Sweden)

    Chiu Yao-Chu

    2007-03-01

    Full Text Available Abstract Background The Iowa gambling task is a popular test for examining monetary decision behavior under uncertainty. According to Dunn et al. review article, the difficult-to-explain phenomenon of "prominent deck B" was revealed, namely that normal decision makers prefer bad final-outcome deck B to good final-outcome decks C or D. This phenomenon was demonstrated especially clearly by Wilder et al. and Toplak et al. The "prominent deck B" phenomenon is inconsistent with the basic assumption in the IGT; however, most IGT-related studies utilized the "summation" of bad decks A and B when presenting their data, thereby avoiding the problems associated with deck B. Methods To verify the "prominent deck B" phenomenon, this study launched a two-stage simple version IGT, namely, an AACC and BBDD version, which possesses a balanced gain-loss structure between advantageous and disadvantageous decks and facilitates monitoring of participant preferences after the first 100 trials. Results The experimental results suggested that the "prominent deck B" phenomenon exists in the IGT. Moreover, participants cannot suppress their preference for deck B under the uncertain condition, even during the second stage of the game. Although this result is incongruent with the basic assumption in IGT, an increasing number of studies are finding similar results. The results of the AACC and BBDD versions can be congruent with the decision literatures in terms of gain-loss frequency. Conclusion Based on the experimental findings, participants can apply the "gain-stay, loss-shift" strategy to overcome situations involving uncertainty. This investigation found that the largest loss in the IGT did not inspire decision makers to avoid choosing bad deck B.

  4. 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.

  5. Experimental investigation of multilayer surfacing system on orthotropic steel bridge with the five-point bending test

    NARCIS (Netherlands)

    Tzimiris, G.; Liu, X.; Scarpas, A.; Li, J.; Hofman, R.; Voskuilen, J.

    2013-01-01

    Due to lightweight and flexibility, orthotropic steel deck bridges become popular the last decades but several problems were reported in relation to asphalt surfacing materials such as rutting, cracking, loss of bond between the surfacing system and steel deck. In the Netherlands a surfacing structu

  6. 一种混凝土桥梁时变体系可靠度分析方法%An approach for evaluating time-variant system reliability of concrete bridges

    Institute of Scientific and Technical Information of China (English)

    田浩; 陈艾荣; 楼慧元

    2012-01-01

    A finite element- and Monte-Carlo simulation-based computational methodology was proposed to evaluate the time-variant system reliability of concrete bridges exposed to aggressive environments. Some essential ingredients involved in the simulation of the lifetime performance and the system reliability were figured out and solved. As for lifetime performance, based on the finite element-based method proposed in previous studies, a program named CBDAS (Concrete Bridge Durability Analysis System) was written in FORTRAN 95 to perform the time-variant performance assessment. In the case of system reliability, a technique for searching the structural failure modes based on the degree of static indeterminacy of the structure was presented, and a program named SRMCS (System Reliability by Monte-Carlo Simulations) was written in MATLAB to evaluate the structural system reliability. As a result, the computational methodology for computing the time-variant system reliability of concrete bridges was set up associated with the solutions of the lifetime performance and the system reliability. Finally, three numerical examples were illustrated to display the functions of CBDAS, SRMCS, and the combination of the two analysis tools.%提出一种基于有限单元法和Monte-Carlo模拟相结合的劣化环境作用时混凝土桥梁时变体系可靠度分析方法,明确并解决结构性能演变模拟和体系可靠度分析中的一些关键问题.根据已有研究成果中给出的基于有限元的分析方法利用FORTRAN 95编写分析程序——混凝土桥梁耐久性分析系统CBDAS来进行结构性能演变过程;提出一种基于结构超静定次数的体系失效模式确定方法,并利用MATLAB编写了分析程序SRMCS来计算结构的体系可靠度.结合结构性能演变模拟和体系可靠度分析给出混凝土桥梁时变体系可靠度的计算方法.最后,利用3个算例分别演示了程序CBDAS,SRMCS以及两者相结合时的分析功能.

  7. Air-Decking Technique in Bench Blasting

    Institute of Scientific and Technical Information of China (English)

    ZHU Hong-bing; LU Wen-bo; WU Liang

    2006-01-01

    The mechanism and the design parameters of blasting with air-decking are studied. The theory of detonation waves is used to investigate the processes of the one-dimensional plane detonation wave within a borehole. The interaction of the rarefaction wave with an interface and reflection on a rigid wall is also analyzed. The same courses of the shock wave are also investigated. This decides the distribution of the pressure of the explosion products changing with time along the borehole. Based on the above theoretical analysis, two conditions should be met for a reasonable range of values of the air-decking ratio in blasting rock. First, the rarefaction wave from the contact interface between detonation products and air reaches the bottom earlier than that of the reflected shock wave from the end of the stemming. Second,the reflected shock wave reaches the contact interface between the detonation products and air earlier than that of the reflected rarefaction wave from the bottom of the borehole. Finally, the reasonable value of the air-decking ratio must be decided theoretically in air-decking blasting. For different explosives, the reasonable range of air-decking ratio varies from 0.15 to 0.4. This result is well consistent with what was obtained by previous researchers.

  8. 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.

  9. Non-destructive inspection protocol for reinforced concrete barriers and bridge railings

    Science.gov (United States)

    Chintakunta, Satish R.; Boone, Shane D.

    2014-02-01

    Reinforced concrete highway barriers and bridge railings serve to prevent errant vehicles from departing the travel way at grade separations. Despite the important role that they play in maintaining safety and their ubiquitous nature, barrier inspection rarely moves beyond visual inspection. In August 2008, a tractor-trailer fatally departed William Preston Lane, Jr. Memorial Bridge after it dislodged a section of the bridge barrier. Investigations following the accident identified significant corrosion of the anchor bolts attaching the bridge railing to the bridge deck. As a result of the information gathered during its investigation of the accident, the National Transportation Safety Board (NTSB) made recommendations to the Federal Highway Administration concerning Non-Destructive Evaluation (NDE) of concrete bridge railings. The Center for nondestructive evaluation (NDE) at Turner Fairbank Highway Research Center in McLean, VA is currently evaluating feasibility of using four technologies - ground penetrating radar (GPR), ultrasonic pulse-echo, digital radiography and infrared thermal imaging methods to develop bridge inspection methods that augment visual inspections, offer reliable measurement techniques, and are practical, both in terms of time and cost, for field inspection work. Controlled samples containing predefined corrosion levels in reinforcing steel were embedded at barrier connection points for laboratory testing. All four NDE techniques were used in the initial phase I testing. An inspection protocol for detecting and measuring the corrosion of reinforced steel embedded in the anchorage system will be developed as part of phase II research. The identified technologies shall be further developed for field testing utilizing a structure with a barrier in good condition and a structure with a barrier in poor condition.

  10. Long-term structural health monitoring of the 2006 Torino's Olympic pedestrian cabled-stayed bridge

    Science.gov (United States)

    Giacosa, L. M.; De Stefano, A.

    2009-03-01

    The currently project is focused on monitoring the reliability, the static and dynamic conditions of the Pedestrian Olympic Bridge in Torino, Italy. Smart sensors based on fiber optic sensors, realized by University of Illinois at Chicago, were installed on the cables. In parallel new low-cost accelerometers and inclinometers sensors, realized by the ChiLab, Italy), were installed on the bridge deck to control statically but also dynamically its behaviour. Acquisition system to collect the data through a continuous monitoring platform, able to pre-process the data, was integrated to manage it locally or in remote way. The performance and reliability of civil infrastructure systems such as bridges are governed by a number of factors including the actual operating and loading environments, complex interactions between structural members and systems, and defect, deterioration and damage mechanisms. These factors are studied dynamically with structural identification of various levels of uncertainty which can be attributed to the fabricated-constructed-erected nature of these systems, variability in site characteristics and conditions, material properties and service loads, and direct exposure to the environment over long life-cycles that are often many decades in length.

  11. 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...

  12. 14 CFR 125.315 - Admission to flight deck.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Admission to flight deck. 125.315 Section...,000 POUNDS OR MORE; AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT Flight Operations § 125.315 Admission to flight deck. (a) No person may admit any person to the flight deck of an airplane unless...

  13. 46 CFR 12.15-13 - Deck engine mechanic.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Deck engine mechanic. 12.15-13 Section 12.15-13 Shipping... ENDORSEMENTS Qualified Member of the Engine Department § 12.15-13 Deck engine mechanic. (a) An applicant for an endorsement as deck engine mechanic shall be a person holding an MMC or MMD endorsed as junior engineer....

  14. Environmental life cycle assessment of railway bridge materials using UHPFRC

    Science.gov (United States)

    Bizjak, Karmen Fifer; Šajna, Aljoša; Slanc, Katja; Knez, Friderik

    2016-10-01

    The railway infrastructure is a very important component of the world's total transportation network. Investment in its construction and maintenance is significant on a global scale. Previously published life cycle assessment (LCA) studies performed on road and rail systems very seldom included infrastructures in detail, mainly choosing to focus on vehicle manufacturing and fuel consumption. This article presents results from an environmental study for railway steel bridge materials for the demonstration case of the Buna Bridge in Croatia. The goal of these analyses was to compare two different types of remediation works for railway bridges with different materials and construction types. In the first part, the environmental impact of the classical concrete bridge construction was calculated, whereas in the second one, an alternative new solution, namely, the strengthening of the old steel bridge with ultra-high-performance fibre-reinforced concrete (UHPFRC) deck, was studied. The results of the LCA show that the new solution with UHPFRC deck gives much better environmental performance. Up to now, results of LCA of railway open lines, railway bridges and tunnels have been published, but detailed analyses of the new solution with UHPFRC deck above the old bridge have not previously been performed.

  15. 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.

  16. I-5/Gilman advanced technology bridge project

    Science.gov (United States)

    Lanza di Scalea, Francesco; Karbhari, Vistasp M.; Seible, Frieder

    2000-04-01

    The UCSD led I-5/Gilman Advanced Technology Bridge Project will design and construct a fully functional traffic bridge of advanced composite materials across Interstate 5 in La Jolla, California. Its objective is to demonstrate the use of advanced composite technologies developed by the aerospace industry in commercial applications to increase the life expectancy of new structures and for the rehabilitation of aging infrastructure components. The structure will be a 450 ft long, 60 ft wide cable-stayed bridge supported by a 150 ft A-frame pylon with two vehicular lanes, two bicycle lanes, pedestrian walkways and utility tunnels. The longitudinal girders and pylon will be carbon fiber shells filled with concrete. The transverse deck system will consist of hollow glass/carbon hybrid tubes and a polypropylene fiber reinforced concrete deck with an arch action. Selected cables will be composite. The bridge's structural behavior will be monitored to determine how advanced composite materials perform in civil infrastructure applications. The bridge will be instrumented to obtain performance and structural health data in real time and, where possible, in a remote fashion. The sensors applied to the bridge will include electrical resistance strain gages, fiberoptic Bragg gratings and accelerometers.

  17. 刚架拱桥斜撑破坏及加固后可靠性分析%Bracing strut failure and its reliability analysis after reinforce in framed arch bridge

    Institute of Scientific and Technical Information of China (English)

    姚良云; 陈燊

    2013-01-01

    Based on the framed arch bridge mechanical behavior and its component structure defects, a solid model of batter brace by means of ANSYS program was established to simulate the reduction of the strength in the wet formed joint of the batter brace, resulting from the descent of the elastic modulus of the concrete. Based on its reliability analysis after reinforce in the framed arch bridge, the the residual service-life of bridge could be predicted.%根据刚架拱桥结构的受力特性和构件本身存在的缺陷,利用斜撑的ANSYS实体模型分析刚架拱桥斜撑的破坏机理,以弹模的降低来模拟斜撑湿接缝处混凝土强度的衰变.研究表明湿接缝处混凝土强度不足是斜撑破坏的主要原因,并对斜撑加固后的可靠性进行分析,预测了斜撑的剩余使用寿命.

  18. 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.

  19. 46 CFR 177.900 - Deck rails.

    Science.gov (United States)

    2010-10-01

    ... of a ferry or a vessel engaged in excursion trips, including but not limited to sightseeing trips... significantly reduce safety. A rail complying with the requirements of paragraphs (d)(1), (2), or (3) of this... exists that is more than 305 millimeters (12 inches) high except: (1) On passenger decks of a ferry or of...

  20. Social psychology on the flight deck

    Science.gov (United States)

    Helmreich, R. L.

    1980-01-01

    Social psychological and personality factors that can influence resource management on the flight deck are discussed. It is argued that personality and situational factors intersect to determine crew responses and that assessment of performance under full crew and mission conditions can provide the most valuable information about relevant factors. The possibility of training procedures to improve performance on these dimensions is discussed.

  1. Deck Yourself with Flu Protection Song

    Centers for Disease Control (CDC) Podcasts

    2009-12-22

    This song (sung to the tune of Deck the Halls) describes actions you can take to protect yourself and others from the flu. Sing along!  Created: 12/22/2009 by National Center for Preparedness, Detection, and Control of Infectious Diseases (NCPDCID), Division of Global Migration and Quarantine (DGMQ).   Date Released: 12/22/2009.

  2. Bridges analysis, design, structural health monitoring, and rehabilitation

    CERN Document Server

    Bakht, Baidar

    2015-01-01

    This book offers a valuable guide for practicing bridge engineers and graduate students in structural engineering; its main purpose is to present the latest concepts in bridge engineering in fairly easy-to-follow terms. The book provides details of easy-to-use computer programs for: ·      Analysing slab-on-girder bridges for live load distribution. ·      Analysing slab and other solid bridge components for live load distribution. ·      Analysing and designing concrete deck slab overhangs of girder bridges under vehicular loads. ·      Determining the failure loads of concrete deck slabs of girder bridges under concentrated wheel loads. In addition, the book includes extensive chapters dealing with the design of wood bridges and soil-steel bridges. Further, a unique chapter on structural health monitoring (SHM) will help bridge engineers determine the actual load carrying capacities of bridges, as opposed to their perceived analytical capacities. The chapter addressing structures...

  3. Application of Composite Structures in Bridge Engineering. Problems of Construction Process and Strength Analysis

    OpenAIRE

    Flaga Kazimierz; Furtak Kazimierz

    2015-01-01

    Steel-concrete composite structures have been used in bridge engineering from decades. This is due to rational utilisation of the strength properties of the two materials. At the same time, the reinforced concrete (or prestressed) deck slab is more favourable than the orthotropic steel plate used in steel bridges (higher mass, better vibration damping, longer life).

  4. 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.

  5. Eye Tracking Metrics for Workload Estimation in Flight Deck Operation

    Science.gov (United States)

    Ellis, Kyle; Schnell, Thomas

    2010-01-01

    Flight decks of the future are being enhanced through improved avionics that adapt to both aircraft and operator state. Eye tracking allows for non-invasive analysis of pilot eye movements, from which a set of metrics can be derived to effectively and reliably characterize workload. This research identifies eye tracking metrics that correlate to aircraft automation conditions, and identifies the correlation of pilot workload to the same automation conditions. Saccade length was used as an indirect index of pilot workload: Pilots in the fully automated condition were observed to have on average, larger saccadic movements in contrast to the guidance and manual flight conditions. The data set itself also provides a general model of human eye movement behavior and so ostensibly visual attention distribution in the cockpit for approach to land tasks with various levels of automation, by means of the same metrics used for workload algorithm development.

  6. Applications of Non-destructive methods (GPR and 3D Laser Scanner) in Historic Masonry Arch Bridge Assessment

    Science.gov (United States)

    Alani, Amir; Banks, Kevin

    2014-05-01

    There exist approximately 70,000 masonry arch bridge spans (brick and stone) in the UK with tens of thousands more throughout Europe. A significant number of these bridges are still in operation and form part of the road and rail network systems in many countries. A great majority of these bridges are in desperate need of repair and maintenance. Applications of non-destructive testing methods such as ground penetrating radar (GPR), 3D laser scanning, accelerometer sensors and vibration detecting sensors amongst many others have been used to assess and monitor such structures in the past few years. This presentation provides results of the applications of a 2GHz GPR antenna system and a 3D laser scanner on a historic masonry arch bridge (the Old Bridge, Aylesford) located in Kent, in the south east of England. The older part of the bridge (the mid-span) is 860 years old. The bridge was the subject of a major alteration in 1811. This presentation forms part of a larger ongoing study which is using the two above mentioned non-destructive methods for long-term monitoring of the bridge. The adopted survey planning strategy and technique, data acquisition and processing as well as challenges encountered during actual survey and fieldworks have been discussed in this presentation. As a result of this study the position of different layers of the deck structure has been established with the identification of the original stone base of the bridge. This information in addition to the location of a number of structural ties (anchors - remedial work carried out previously) in the absence of reliable and accurate design details proved to be extremely useful for the modelling of the bridge using the finite element method. Results of the 3D laser scanning of the bridge have also been presented which have provided invaluable data essential for the accurate modelling of the bridge as well as the long term monitoring of the bridge. 2014 EGU-GA GI3.1 Session, organised by COST Action

  7. Fatigue Reliability Analysis of Multi-loading Suspension Bridges Considering Nonlinear Accumulative Damage%考虑非线性累积损伤的大跨多荷载桥梁的疲劳可靠度评估

    Institute of Scientific and Technical Information of China (English)

    陈志为; 徐幼麟

    2014-01-01

    针对大跨多荷载桥梁疲劳损伤累积非线性过程中的大量不确定性,对火车、汽车与风荷载作用下的大跨悬索桥,利用连续损伤模型提出了一个疲劳可靠度评估方法。首先,在连续损伤模型基础上,对模型参数进行分析;然后,根据工程应用的需要,适当简化疲劳模型,在连续损伤模型中引入合适的随机变量,定义疲劳可靠度分析的极限状态函数,假定多种未来可能的交通荷载和荷载增长模式,利用蒙特卡洛方法产生随机变量并计算失效概率;最后以香港青马大桥为例,讨论了该桥在不同荷载状况下使用120年后的疲劳失效概率。研究发现:若保持当前的交通状态,桥梁可保持良好状况,但未来交通荷载的快速增长会导致结构提前失效。%Taking into account uncertainties in the nonlinear process of fatigue damage accumulation for fatigue reliability analysis of multi-loading long-span bridges,a fatigue reliability assessment method for a long suspension bridge under combined highway,railway,and wind loadings was proposed using a continuum damage model (CDM ). First,the CDM based on continuum damage mechanics was briefly introduced,and main model parameters were analyzed. Then,a simplified CDM was proposed for further application to bridge structures. A limit state function for fatigue reliability analysis based on CDM was defined by introducing proper random variables into the CDM. The Monte Carlo simulation (MCS)was adopted to generate the random variables and to calculate the failure probability. Finally, the Tsing Ma Bridge in Hong Kong was taken as a case study,and the failure probabilities of the bridge at the end of 120 years were estimated for different loading scenarios. The results indicate that the health condition of the bridge in fatigue is satisfactory under the current traffic conditions,but attentions should be paid to future traffic growth because it

  8. Measurement of Prestressing Force in Pretensioned UHPC Deck Using a Fiber Optic FBG Sensor Embedded in a 7-Wire Strand

    Directory of Open Access Journals (Sweden)

    Jae-min Kim

    2016-01-01

    Full Text Available This paper presents the results of the performance test and long-term monitoring of the prestressing force inside concrete performed on a pretensioned Ultra-High Performance Concrete (UHPC deck. The force is measured by applying a 7-wire strand embedded with an FBG (Fiber Bragg Grating sensor. The performance test was conducted on a 3.7 m × 1.8 m pretensioned deck specimen through wheel loading tests to verify the applicability of the measurement method. In addition, a 12.3 m long and 4.8 m wide bridge with a pretensioned UHPC deck was erected and long-term monitoring was conducted over three years to verify the applicability of the method to real bridges. The effectiveness of the measurement method of the prestressing force inside concrete is verified, and the long-term monitoring data are used to investigate various temperature compensation methods. The results show that the proposed method enables effective measurement of small changes in the prestressing force inside the concrete. These changes are caused by the external forces acting on the bridge in service and provide sufficient durability for long-term sensing. The analysis of the prestressing force obtained through long-term monitoring reveals the necessity of conducting temperature compensation for the consistency of the data acquired using the FBG sensor. Moreover, the selection of the thermal expansion coefficient appears also to be of critical importance for temperature compensation.

  9. Influences of Loads on Vehicles and Lanes on Reliability of Bridge Structures%车辆荷载和车道荷载对桥梁结构可靠度的影响

    Institute of Scientific and Technical Information of China (English)

    陈名扬; 王起才

    2012-01-01

    公路桥梁结构的整体计算采用车道荷载,结构的局部计算采用车辆荷载,车辆荷载与车道荷载的作用不得叠加.将采用这2种荷载设计的结构进行可靠度对比,结果表明,按车辆荷载设计的结构满足正常使用功能的可靠度偏低,更容易发生损坏,这些损坏会影响到结构的正常使用.提出通过调整重型车辆通过桥梁时的交通行驶规则,增大结构按正常使用极限状态设计时车辆荷载的代表值,从而提高按车辆荷载设计的结构可靠度.%Integral calculation for highway bridge structures adopts loads on lanes, local calculation for structures employs loads on vehicles, and the effects of loads on vehicles and lanes should not be superimposed. This paper compares reliabilities of structures designed by means of these two loads, the result show that the reliability of structures designed based on loads on vehicles to satisfy normal functions of use is lower and easier to damages, which will affect normal use of structures. The paper proposes to increase effect values of actions of loads on vehicles during design in limit state of normal use by adjusting traffic driving rules as heavy vehicles pass bridges so as to improve reliability of structures designed on the basis of loads on vehicles.

  10. Study on low temperature performance of Gussasphalt on steel decks with hard bitumen

    Institute of Scientific and Technical Information of China (English)

    YangJun

    2003-01-01

    Using a Hamburg wheel-traek test device, the resistance to rutting of Gussasphalt is tested and compared.Gussasphalt with hard bitumen has good resistance to rutting. The related resistance abilities to cracking at low temperature of Gussasphalt are tested and compared through flexural experiments and the composite structure fatigue test with temperature dropping. Gussasphalt with high pedormanee polymer modified bitumen has a longer fatigue life and a lower breaking temperature; they can be used in the future sudaces for steel bridge decks in Germany.

  11. RELIABLE HYSTERESIS CURRENT CONTROLLED DUAL BUCK HALF BRIDGE INVERTER%一种可靠的滞环电流型双降压式半桥逆变电路

    Institute of Scientific and Technical Information of China (English)

    刘军; 严仰光

    2003-01-01

    研究了一种新颖的双降压式半桥逆变电路(Dual buck half bridge inverter,DBI),该电路有无直通,效率高等特点.提出了一种DBI的无偏置电流运行方式和一种滞环电流型双降压式半桥逆变电路(Hysteresis current controlled dual buck half bridge inverter,HCDBI),消除了采用载波交截SPWM控制DBI正常工作所必需的偏置电流,进一步提高了效率.对HCDBI和传统半桥逆变器进行了理论上的损耗计算分析和实验验证,证明了HCBBI可大幅降低开关损耗,开关频率高,滤波器小.为实现逆变器的高频化提供了一种简洁的方法和新的途径.%A highly efficient and reliable topology-dual buck half bridge inverter (DBI) is introduced. The existence of discontinuous conduction mode (DCM) operation state requires the bias of inductor current for DBI implemented with linear controllers like ramp comparison SPWM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis current controlled dual buck half bridge inverter (HCDBI) are proposed. The bias current required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational scheme and control strategy are presented. Power losses of the conventional half bridge inverter (CHBI) and HCDBI are compared with mathematical computation, and experimental verification is also executed. Both calculational and experimental results verify that HCDBI has a superior switching performance over CHBI. Its excellent high frequency operational capacity provides another access to realize high frequency operation of inverters.

  12. 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.

  13. Thermal analysis of GFRP-reinforced continuous concrete decks subjected to top fire

    Science.gov (United States)

    Hawileh, Rami A.; Rasheed, Hayder A.

    2017-09-01

    This paper presents a numerical study that investigates the behavior of continuous concrete decks doubly reinforced with top and bottom glass fiber reinforced polymer (GFRP) bars subjected to top surface fire. A finite element (FE) model is developed and a detailed transient thermal analysis is performed on a continuous concrete bridge deck under the effect of various fire curves. A parametric study is performed to examine the top cover thickness and the critical fire exposure curve needed to fully degrade the top GFRP bars while achieving certain fire ratings for the deck considered. Accordingly, design tables are prepared for each fire curve to guide the engineer to properly size the top concrete cover and maintain the temperature in the GFRP bars below critical design values in order to control the full top GFRP degradation. It is notable to indicate that degradation of top GFRP bars do not pose a collapse hazard but rather a serviceability concern since cracks in the negative moment region widen resulting in simply supported spans.

  14. DeckLink SDI采集卡

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Blackmagic Design的DeckLink SDI采集卡,具有高质量10b高/标清SDI采集和回放能力。它还配有广播级SDI,能够在SD—SDI和HD—SDI格式之间即时转换,非常适合连接HDCAM、HD—D5和Digital Betacam等录机。

  15. 46 CFR 178.450 - Calculation of drainage area for cockpit and well deck vessels.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Calculation of drainage area for cockpit and well deck....450 Calculation of drainage area for cockpit and well deck vessels. (a) The drainage area required on... cockpit deck; DR=total deck area of the cockpit or well deck in the after 2/3 of the vessel length...

  16. 46 CFR 28.565 - Water on deck.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Water on deck. 28.565 Section 28.565 Shipping COAST... VESSELS Stability § 28.565 Water on deck. (a) Each vessel with bulwarks must comply with the requirements... energy, “b” in Figure 28.565, must not be less than the water on deck heeling energy, “a” in Figure...

  17. "The Battery" designed with Super-Light (concrete) Decks

    DEFF Research Database (Denmark)

    Castberg, Niels Andreas; Hertz, Kristian Dahl

    the cantilevered internal corridors are investigated. Super-Light Structures is a newly patented structural concrete concept. Slabs based on the concept are the first structural element developed under the patent. The slabs called SL-decks have multiple advantages compared to traditional hollow core slabs....... The paper aims to describe the concept of how the deck can be used in these innovative buildings and how the special advantages of the SL-decks are applied....

  18. Non-intrusive schemes for speed and axle identification in bridge-weigh-in-motion systems

    Science.gov (United States)

    Kalhori, Hamed; Makki Alamdari, Mehrisadat; Zhu, Xinqun; Samali, Bijan; Mustapha, Samir

    2017-02-01

    Bridge weigh-in-motion (BWIM) is an approach through which the axle and gross weight of trucks travelling at normal highway speed are identified using the response of an instrumented bridge. The vehicle speed, the number of axles, and the axle spacing are crucial parameters, and are required to be determined in the majority of BWIM algorithms. Nothing-on-the-road (NOR) strategy suggests using the strain signals measured at some particular positions underneath the deck or girders of a bridge to obtain this information. The objective of this research is to present a concise overview of the challenges of the current non-intrusive schemes for speed and axle determination through bending-strain and shear-strain based approaches. The problem associated with the global bending-strain responses measured at quarter points of span is discussed and a new sensor arrangement is proposed as an alternative. As for measurement of local responses rather than the global responses, the advantage of shear strains over bending strains is presented. However, it is illustrated that shear strains at quarter points of span can only provide accurate speed estimation but fail to detect the correct number of axles. As a remedy, it is demonstrated that, even for closely-spaced axles, the shear strain at the beginning of the bridge is capable of reliably identifying the number of axles. In order to provide a fully automated speed and axle identification system, appropriate signal processing including low-pass filtering and wavelet transforms are applied to the raw time signals. As case studies, the results of experimental testing in laboratory and on a real bridge are presented.

  19. 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...

  20. Fatigue monitoring and analysis of orthotropic steel deck considering traffic volume and ambient temperature

    Institute of Scientific and Technical Information of China (English)

    SONG; YongSheng; DING; YouLiang

    2013-01-01

    Fatigue has gradually become a serious issue for orthotropic steel deck used for long-span bridges. Two fatigue effects, namely number of stress cycles and equivalent stress amplitude, were introduced as investigated parameters in this paper. Investigation was focused on their relationships with traffic volume and ambient temperature by using 7-months fatigue monitoring data of an actual bridge. A fatigue analytical model considering temperature-induced changes in material property of asphalt pavement was established for verifying these relationships. The analysis results revealed that the number of stress cycles and equivalent stress amplitude showed a linear correlation with the traffic volume and ambient temperature, respectively, and that the rib-to-deck welded joint was much more sensitive to the traffic volume and ambient temperature than the rib-to-rib welded joint. The applicability of the code-recommended model for fatigue vehicle loading was also discussed, which revealed that the deterministic vehicle loading model requires improvement to account for significant randomness of the actual traffic conditions.

  1. effect of uncertainty on the fatigue reliability of reinforced concrete ...

    African Journals Online (AJOL)

    user

    2016-07-03

    Jul 3, 2016 ... deterioration and much heavier vehicle loads, the safety of the existing deteriorating bridge decks in the later life cycle is more critical [15]. ... problem, it is also a risk to those who traverse the structure. Forms of deterioration ...

  2. Protecting wood decks from biodegradation and weathering : evaluation of deck finish systems

    Science.gov (United States)

    J. J. Morrell; P. F. Schneider; R. Sam Williams

    2001-01-01

    Mildew resistance, water repellency, and overall finish appearance were evaluated for 32 deck finishes on western redcedar (Thuja plicata D. Donn.) and Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) after 12, 21, and 39 months of outdoor exposure in western Oregon. The finishes were either solvent-borne or waterborne; were ei- ther clear, tinted, or lightly...

  3. Smart suspension systems for bridge-friendly vehicles

    Science.gov (United States)

    Chen, Yonghong; Tan, Chin An; Bergman, Larry A.; Tsao, T. C.

    2002-06-01

    In this paper, the effects of using semi-active control strategy (such as MR dampers) in vehicle suspensions on the coupled vibrations of a vehicle traversing a bridge are examined in order to develop various designs of smart suspension systems for bridge-friendly vehicles. The bridge-vehicle coupled system is modeled as a simply supported beam traversed by a two-degree-of-freedom quarter-car model. The surface unevenness on the bridge deck is modeled as a deterministic profile of a sinusoidal wave. As the vehicle travels along the bridge, the system is excited as a result of the surface unevenness and this excitation is characterized by a frequency defined by the speed of travel and the wavelength of the profile. The dynamic interactions between the bridge and the vehicle due to surface deck irregularities are obtained by solving the coupled equations of motion. Numerical results of a passive control strategy show that, when the lower natural frequency of the vehicle matches with a natural frequency (usually the first frequency) of the bridge and the excitation frequency, the maximum response of the bridge is large while the response of the vehicle is relatively smaller, meaning that the bridge behaves like a vibration absorber. This is undesirable from a bridge design viewpoint. Comparative studies of passive and semi-active controls for the vehicle suspension are performed. It is demonstrated that skyhook control can significantly mitigate the response of the bridge, while ground-hook control reduces the tire force impacted onto the bridge.

  4. 33 CFR 401.32 - Cargo booms-deck cargo.

    Science.gov (United States)

    2010-07-01

    ... 33 Navigation and Navigable Waters 3 2010-07-01 2010-07-01 false Cargo booms-deck cargo. 401.32... OF TRANSPORTATION SEAWAY REGULATIONS AND RULES Regulations Seaway Navigation § 401.32 Cargo booms—deck cargo. (a) Every vessel shall have cargo booms secured in a manner that affords maximum...

  5. 14 CFR 121.547 - Admission to flight deck.

    Science.gov (United States)

    2010-01-01

    ... 14 Aeronautics and Space 3 2010-01-01 2010-01-01 false Admission to flight deck. 121.547 Section 121.547 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION (CONTINUED... REQUIREMENTS: DOMESTIC, FLAG, AND SUPPLEMENTAL OPERATIONS Flight Operations § 121.547 Admission to flight deck...

  6. 29 CFR 1915.165 - Ship's deck machinery.

    Science.gov (United States)

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Ship's deck machinery. 1915.165 Section 1915.165 Labor... (CONTINUED) OCCUPATIONAL SAFETY AND HEALTH STANDARDS FOR SHIPYARD EMPLOYMENT Ship's Machinery and Piping Systems § 1915.165 Ship's deck machinery. (a) Before work is performed on the anchor windlass or any...

  7. 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.

  8. Investigation of Influence Factors of Wind-Induced Buffeting Response of a Six-Tower Cable-Stayed Bridge

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Zhang

    2016-01-01

    Full Text Available This paper presents an investigation of the wind-induced buffeting responses of the Jiashao Bridge, the longest multispan cable-stayed bridge in the world. A three-dimensional finite element model for the Jiashao Bridge is established using the commercial software package ANSYS and a 3D fluctuating wind field is simulated for both bridge deck and towers. A time-domain procedure for analyzing buffeting responses of the bridge is implemented in ANSYS with the aeroelastic effect included. The characteristics of buffeting responses of the six-tower cable-stayed bridge are studied in some detail, focusing on the effects including the difference in the longitudinal stiffness between the side towers and central towers, partially longitudinal constraints between the bridge deck and part of bridge towers, self-excited aerodynamic forces, and the rigid hinge installed in the middle of the bridge deck. The analytical results can provide valuable references for wind-resistant design of multispan cable-stayed bridges in the future.

  9. Parametric Study of Open Trough Steel Concrete Composite Deck

    Directory of Open Access Journals (Sweden)

    Merool Devarsh Vakil

    2015-01-01

    Full Text Available Steel concrete composite deck is used in many parts of the world as fast and economical structural system. Recently the techniques are getting attention in India also. The profile deck is made up of thin cold formed steel sheet which can be formed in any desired shape. In this paper, critical study is made by varying the geometrical and material strength parameters of steel concrete deck. Its effect on flexural resistance and neutral axis location is analyzed. Ductile behavior of deck is another important concern. Here, authors put forward the limiting value of neutral axis for commonly used grades of steel for profile deck, which should be checked to ensure ductile behavior of composite deck. The paper considers variations in concrete thickness, yield strength of material, cylinder strength of concrete for an open trough type profile deck .Analysis of moment of resistance and depth of neutral axis are made as per Euro code EN-1994 assuming full bond between steel and concrete. The results show that there is significant variation in flexural capacity and neutral axis location on varying geometrical and material parameters.

  10. Orbiter Flight Deck Redesign (A Physical Layout for a Futuristic Flight Deck)

    Science.gov (United States)

    Khorsandi, Mehrzad

    1996-01-01

    The purpose of this summer project was to develop a set of schematic drawings for redesign of the Space Shuttle flight deck from which three dimensional computer drawings can be built and viewed in a virtual environment. In order to achieve this goal, first recommendations for overall redesign of Space Shuttle previously made by experts in the field were reviewed and relevant information was extracted and delineated. Original drawings of the Space Shuttle made by Rockwell were obtained and carefully examined. In order to implement and assess any modifications in terms of space saving parameters, it was determined that the drawings alone could not achieve this objective. As a complement, physical measurements of the mockup of Space Shuttle flight deck were made and the information was categorized and properly labeled on the original drawings. Then, spacesaving redesign ideas, as motivated by expert recommendations on such things as information display panel upgrade by technologically advanced flat display units, were implemented. Next, the redesign ideas were executed on the Forward flight deck, Overhead Console, Right and Left Console, and Center Console. A new 3-D computer drawing of this was developed by modifying the existing drawing on the in-house developed software (PLAID). Finally, the drawing was transported to a Virtual Environment and observed.

  11. 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.

  12. 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....

  13. Dynamic Analysis of Horizontally Curved Thin-Walled Box-Girder Bridge due to Moving Vehicle

    Directory of Open Access Journals (Sweden)

    K. Nallasivam

    2007-01-01

    Full Text Available The impact on curved box-girder bridges due to vehicle moving across rough bridge deck have been analyzed using bridge-vehicle coupled dynamics. The bridge deck unevenness has been assumed to be a homogeneous random process in space specified by a PSD function. The analysis incorporates the effect of centrifugal forces due to vehicle moving on curved bridge. The curved box-girder bridge has been numerically modeled using computationally efficient thin-walled box-beam finite elements which take into account the torsional warping, distortion and distortional warping, that are important features of thin-walled box girders. Rigid vehicle with longitudinal and transverse input to the wheels giving rise to heave-pitch-roll degrees of freedom has been considered. The theoretical bridge model used in simulation study has been validated by a free vibration experiment using impact excitation. The impact factors for several response parameters such as bending moment, shear force, torsional moment, torsional bi-moment, distortional moment, distortional bi-moment and vertical deflections have been obtained for various bridge-vehicle parameters. Both constant velocity and forward acceleration of the vehicle have been considered to examine impact factor. The results highlighted that the impact factors of a curved box girder bridge corresponding to torsion, distortion and their corresponding bimoments have been observed to be generally very high, while those of the other responses are also relatively higher than that of corresponding straight box girder bridge.

  14. Running safety analysis of a train on the Tsing Ma Bridge under turbulent winds

    Institute of Scientific and Technical Information of China (English)

    Guo Weiwei; Xia He; Xu Youlin

    2010-01-01

    The dynamic responses of the Tsing Ma suspension bridge and the running behaviors of trains on the bridge under turbulent wind actions are analyzed by a three-dimensional wind-train-bridge interaction model. This model consists of a spatial finite element bridge model, a train model composed of eight 4-axle identical coaches of 27 degrees-of-freedom, and a turbulent wind model. The fluctuating wind forces, including the buffeting forces and the self-excited forces, act on the bridge only, since the train runs inside the bridge deck. The dynamic responses of the bridge are calculated and some results are compared with data measured from Typhoon York. The runnability of the train passing through the Tsing Ma suspension bridge at different speeds is researched under turbulent winds with different wind velocities. Then, the threshold curve of wind velocity for ensuring the running safety of the train in the bridge deck is proposed, from which the allowable train speed at different wind velocities can be determined. The numerical results show that rail traffic on the Tsing Ma suspension bridge should be closed as the mean wind velocity reaches 30 m/s.

  15. Multiobjective Optimal Control of Longitudinal Seismic Response of a Multitower Cable-Stayed Bridge

    Directory of Open Access Journals (Sweden)

    Geng Fangfang

    2016-01-01

    Full Text Available The dynamic behavior of a multitower cable-stayed bridge with the application of partially longitudinal constraint system using viscous fluid dampers under real earthquake ground motions is presented. The study is based on the dynamic finite element model of the Jiashao Bridge, a six-tower cable-stayed bridge in China. The prime aim of the study is to investigate the effectiveness of viscous fluid dampers on the longitudinal seismic responses of the bridge and put forth a multiobjective optimization design method to determine the optimized parameters of the viscous fluid dampers. The results of the investigations show that the control objective of the multitower cable-stayed bridge with the partially longitudinal constraint system is to yield maximum reductions in the base forces of bridge towers longitudinally restricted with the bridge deck, with slight increases in the base forces of bridge towers longitudinally unrestricted with the bridge deck. To this end, a multiobjective optimization design method that uses a nondominating sort genetic algorithm II (NSGA-II is used to optimize parameters of the viscous fluid dampers. The effectiveness of the proposed optimization design method is demonstrated for the multitower cable-stayed bridge with the partially longitudinal constraint system, which reveals that a design engineer can choose a set of proper parameters of the viscous fluid dampers from Pareto optimal fronts that can satisfy the desired performance requirements.

  16. Probabilistic Corrosion Service Life Model of Concrete Bridge Exposed to Chloride Deicer Salts

    Directory of Open Access Journals (Sweden)

    Cristian-Claudiu Comisu

    2005-01-01

    Full Text Available A model to determine the time till first repair and subsequent rehabilitation of concrete bridge decks exposed to chloride deicer salts that recognizes and incorporates the statistical nature of factors affecting the corrosion process, consists of the following serial phases: diffusion to the depth of the steel that would precipitate first maintenance actions; corrosion of the steel at the first maintenance depth until cracking and spalling occurs; continuous spalling until a damage level is reached which is defined as the end of functional service life for the deck of concrete bridge. The model expands on an existing deterministic model using statistical computing techniques, including resampling techniques such as the parametric and simple bootstrap. Emphasis was placed on the diffusion portion of the diffusion-cracking model, but advances can be readily included for the time for corrosion deterioration after corrosion initiation. The diffusion phase is described by Fick’s law and the boundary conditions define the solution form. The time till cracking model depends upon some factors as concrete strength properties, cover depth and corrosion rate. Corrosion rate has a significant influence on the time to cracking which typically occurs in three to seven years after initiation. Service life model that predict the time to first repair and rehabilitation of concrete bridge decks provide a useful tool for comparing the effectiveness measures and provide bridge engineers with a useful planning tool. A service life model for the corrosion of concrete bridge deck in chloride laden environments is proposed. The aim of this paper is to enhance the awareness among the engineering community to use the model to determine the time till first repair and subsequent rehabilitation of concrete bridge decks exposed to chloride deicer salts in Romania.

  17. Super-light concrete decks for building floor slabs

    DEFF Research Database (Denmark)

    Hertz, Kristian Dahl; Castberg, Niels Andreas; Christensen, Jacob

    2014-01-01

    to flexibility, sound insulation and fire resistance compared with present-day prefabricated structures. Full-scale tests and theoretical investigations show that the deck structure performs as intended. Also, that it is possible to assess by calculation the loadbearing capacity in bending and shear, and assess......This paper presents investigations carried out at the Technical University of Denmark (DTU) on a prototype series for a super-lightweight prestressed concrete deck element called the SL-Deck. The intention behind making a new prefabricated deck element is to improve performance with respect...... the pull-out strength of prestressing wires, the fire resistance and the acoustic insulation. Based on the results of the investigations, recommendations are given for further development of the structure before fully automated mass production is established....

  18. Influence of maximum decking charge on intensity of blasting vibration

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Based on the character of short-time non-stationary random signal, the relationship between the maximum decking charge and energy distribution of blasting vibration signals was investigated by means of the wavelet packet method. Firstly, the characteristics of wavelet transform and wavelet packet analysis were described. Secondly, the blasting vibration signals were analyzed by wavelet packet based on software MATLAB, and the change of energy distribution curve at different frequency bands were obtained. Finally, the law of energy distribution of blasting vibration signals changing with the maximum decking charge was analyzed. The results show that with the increase of decking charge, the ratio of the energy of high frequency to total energy decreases, the dominant frequency bands of blasting vibration signals tend towards low frequency and blasting vibration does not depend on the maximum decking charge.

  19. 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....

  20. 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....

  1. 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,...

  2. 76 FR 31451 - Special Conditions: Boeing Model 747-8 Airplanes; Stairway Between the Main Deck and Upper Deck

    Science.gov (United States)

    2011-06-01

    ... takeoff weight of 975,000 pounds, new General Electric GEnx -2B67 engines, and the capacity to carry 605... provided along the stairs. 11. When passengers occupy the upper deck, at least one flight attendant must...

  3. Structure-borne noise of railway composite bridge: Numerical simulation and experimental validation

    Science.gov (United States)

    Li, Xiaozhen; Liu, Quanmin; Pei, Shiling; Song, Lizhong; Zhang, Xun

    2015-09-01

    In order to investigate the characteristics of the noise from steel-concrete composite bridges under high-speed train loading, a model used to predict the bridge-borne noise is established and validated through a field experiment. The numerical model for noise prediction is developed based on the combination of spatial train-track-bridge coupled vibration theory and Statistical Energy Analysis (SEA). Firstly, train-track-bridge coupled vibration is adopted to obtain the velocity time history of the bridge deck vibration. Then, the velocity time history is transferred into frequency domain through FFT to serve as the vibratory energy of SEA deck subsystems. Finally, the transmission of the vibratory energy is obtained by solving the energy balance equations of SEA, and the sound radiation is computed using the vibro-acoustic theory. The numerically computed noise level is verified by a field measurement. It is determined that the dominant frequency of steel-concrete composite bridge-borne noise is 20-1000 Hz. The noise from the bottom flange of steel longitudinal girder is less than other components in the whole frequency bands, while the noise from web of steel longitudinal girder is dominant in high frequency range above 315 Hz. The noise from concrete deck dominates in low-frequency domain ranges from 80 Hz to 160 Hz.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Seismic Response Analysis of Continuous Multispan Bridges with Partial Isolation

    Directory of Open Access Journals (Sweden)

    E. Tubaldi

    2015-01-01

    Full Text Available Partially isolated bridges are a particular class of bridges in which isolation bearings are placed only between the piers top and the deck whereas seismic stoppers restrain the transverse motion of the deck at the abutments. This paper proposes an analytical formulation for the seismic analysis of these bridges, modelled as beams with intermediate viscoelastic restraints whose properties describe the pier-isolator behaviour. Different techniques are developed for solving the seismic problem. The first technique employs the complex mode superposition method and provides an exact benchmark solution to the problem at hand. The two other simplified techniques are based on an approximation of the displacement field and are useful for preliminary assessment and design purposes. A realistic bridge is considered as case study and its seismic response under a set of ground motion records is analyzed. First, the complex mode superposition method is applied to study the characteristic features of the dynamic and seismic response of the system. A parametric analysis is carried out to evaluate the influence of support stiffness and damping on the seismic performance. Then, a comparison is made between the exact solution and the approximate solutions in order to evaluate the accuracy and suitability of the simplified analysis techniques for evaluating the seismic response of partially isolated bridges.

  9. Problems associated with nondestructive evaluation of bridges

    Science.gov (United States)

    Prine, David W.

    1995-05-01

    The US has 542,000 bridges that consume billions of dollars per year in construction, rehabilitation, and maintenance funds and which are the lifelines of US commerce. The 1992 ISTEA (Intermodal Surface Transportation Efficiency Act) mandates the implementation of a quantitative computerized bridge management system by 1996. A prime need of such a system are quantitative bridge inspection methods to feed accurate reliable condition information to the huge database of bridges. Nondestructive evaluation (NDE) will fill a critical need in the implementation of effective bridge management. However, many serious barriers exist to the widespread routine application of this technology to bridges. This paper provides an overview of the typical problems associated with applying NDE to bridges.

  10. Re-Assessment of Concrete Bridges

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    In this paper two aspects of re-assessment of the reliability of concrete bridges are discussed namely modelling of the corrosion of reinforcement and updating of uncertain variables. The main reason for deterioration of concrete bridges is corrosion of the reinforcement. Therefore, modelling...

  11. 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.

  12. 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.

  13. P-D Effects on the Reliability of Oil Offshore Jacket Platforms in Mexico

    Directory of Open Access Journals (Sweden)

    De León-Escobedo D.

    2012-07-01

    Full Text Available Given the important economic consequences of an oil platform failure, all the aspects of its structural behavior and safety issues need to be carefully considered. In particular, P-Δ effects on the deck legs of marine offshore jacket platforms may be relevant when the deck height and the vertical load are significant. In this paper, the impact of the moment amplification, due to slenderness of the deck legs, on the platform safety is examined and appraised from the viewpoint of the structural reliability. The formulation is applied to a typical tall deck marine platform under the environmental loading at the Bay of Campeche, Mexico, and its reliability index is calculated with and without the P-Δeffect. The results presented herein may be used to improve the current practice in the design and assessment of offshore marine platforms in Mexico and to update the current version of the code.

  14. Investigations on Efficiently Interfaced Steel Concrete Composite Deck Slabs

    Directory of Open Access Journals (Sweden)

    K. N. Lakshmikandhan

    2013-01-01

    Full Text Available The strength of the composite deck slab depends mainly on the longitudinal shear transfer mechanism at the interface between steel and concrete. The bond strength developed by the cement paste is weak and causes premature failure of composite deck slab. This deficiency is effectively overcame by a shear transferring mechanism in the form of mechanical interlock through indentations, embossments, or fastening studs. Development of embossment patterns requires an advanced technology which makes the deck profile expensive. Fastening studs by welding weakens the joint strength and also escalates the cost. The present investigation is attempted to arrive at a better, simple interface mechanism. Three types of mechanical connector schemes are identified and investigated experimentally. All of the three shear connector schemes exhibited full shear interaction with negligible slip. The strength and stiffness of the composite slabs with shear connectors are superior about one and half time compared to these of the conventional reinforced concrete slabs and about twice compared to these of composite slabs without mechanical shear connectors. The scheme2 and scheme3 shear connector mechanisms integrate deck webs and improve strength and stiffness of the deck, which can effectively reduce the cost of formworks and supports efficiently.

  15. Ambient Response Analysis of the Great Belt Bridge

    DEFF Research Database (Denmark)

    Brincker, Rune; Frandsen, J. B.; Andersen, P.

    2000-01-01

    In this paper an ambient response analysis of the Great Belt Bridge is presented. The Great Belt Bridge is one of the largest suspension bridges in the world, and the analysis was carried out in order to investigate the possibilities of estimating reliable damping values from the ambient response...

  16. Strategic Planning for the National Bridge Stock of Iran

    Directory of Open Access Journals (Sweden)

    Ali Sahrapeyma

    2013-06-01

    Full Text Available The National Bridge Stock of Iran consists of about 330,000 bridges, of which around 50% are older than 30 years. Since 2010, Iran Road Maintenance & Transportation Organization has started implementing a comprehensive Bridge Management System in order to manage this aged stock efficiently. To predict future conditions of bridge stock, a heuristic numerical method is presented. This methodology is based on Markovian process to model deterioration of bridge decks and a multi-objective optimization problem to find the best solutions. The optimization problem involves three decision variables regarding management strategies, and has three objectives regarding cost minimization. Constraints of the problem are the percentage of deficient bridges, the percentage of bridges under MR&Rs (Maintenance, Repair and Rehabilitation and the average value of condition scores. The results show that to avoid future challenges, the annual budget for bridge maintenance should be increased, the current maintenance strategy should be improved as soon as possible, and national manuals and instructions for inspection, condition rating and maintenance should be developed.

  17. Optimum Maintenance Strategies for Highway Bridges

    DEFF Research Database (Denmark)

    Frangopol, Dan M.; Thoft-Christensen, Palle; Das, Parag C.;

    As bridges become older and maintenance costs become higher, transportation agencies are facing challenges related to implementation of optimal bridge management programs based on life cycle cost considerations. A reliability-based approach is necessary to find optimal solutions based on minimum...... expected life-cycle costs or maximum life-cycle benefits. This is because many maintenance activities can be associated with significant costs, but their effects on bridge safety can be minor. In this paper, the program of an investigation on optimum maintenance strategies for different bridge types...... is described. The end result of this investigation will be a general reliability-based framework to be used by the UK Highways Agency in order to plan optimal strategies for the maintenance of its bridge network so as to optimize whole-life costs....

  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. 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.

  1. 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.

  2. Experimental Study of Properties of Pervious Concrete used for Bridge Superstructure

    DEFF Research Database (Denmark)

    Lund, Mia Schou Møller; Hansen, Kurt Kielsgaard; Hertz, Kristian Dahl

    2014-01-01

    -Chain Bridges are a new patented bridge technology consisting of a number of Super-Light Deck elements, which are post-tensioned to create an arch bridge used for example for highways. The present study investigates how pervious concrete can be applied as a stabilizing filling materi-al between the arch...... substructure and the wearing course. One pervious concrete mixture contain-ing air entrainment is designed and tested. The tests include investigations of compaction meth-ods, compressive strength, stiffness, frost resistance and permeability....

  3. 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.

  4. 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.

  5. Fiber reinforced polymer composites for bridge structures

    Directory of Open Access Journals (Sweden)

    Alexandra CANTORIU

    2013-12-01

    Full Text Available Rapid advances in construction materials technology have led to the emergence of new materials with special properties, aiming at safety, economy and functionality of bridges structures. A class of structural materials which was originally developed many years ago, but recently caught the attention of engineers involved in the construction of bridges is fiber reinforced polymer composites. This paper provides an overview of fiber reinforced polymer composites used in bridge structures including types, properties, applications and future trends. The results of this study have revealed that this class of materials presents outstanding properties such as high specific strength, high fatigue and environmental resistance, lightweight, stiffness, magnetic transparency, highly cost-effective, and quick assembly, but in the same time high initial costs, lack of data on long-term field performance, low fire resistance. Fiber reinforced polymer composites were widely used in construction of different bridge structures such as: deck and tower, I-beams, tendons, cable stands and proved to be materials for future in this field.

  6. 港珠澳大桥青州航道桥工程特点及关键技术%Engineering Characteristics and Key Techniques of Qingzhou Ship Channel Bridge of Hong Kong-Zhuhai-Macao Bridge

    Institute of Scientific and Technical Information of China (English)

    刘明虎; 孟凡超; 李国亮

    2013-01-01

    The Qingzhou Ship Channel Bridge of the Hong Kong-Zhuhai-Macao Bridge is a steel box girder cable-stayed bridge with double pylons and double cable planes.In the design of the bridge,a variety of the new materials,new techniques and new workmanships have been applied.In this paper,the engineering characteristics and key techniques of the bridge are summarized.On the bridge,the steel box girders of the same structural types of the adjacent non-navigable span bridges are fully used as the counterweight and on the outer side spans of the bridge,the stay cables are not installed.The arrangement of the bridge in such a way is well appropriate to the local conditions of the bridge site and has notable comprehensive advantage.The structural support system of the bridge is the three-way system that can ensure the structural performance of the whole bridge to be optimal.The pylons have the crisscross steel struts of the “Chinese Knot” configuration,which are connected with the concrete pylon columns via the connecting boxes in a combined force transmitting mode of “ compression-shear” and the performance of the steel struts and connection is safe and reliable.The foundations for the bridge are the composite piles of variable diameter steel pipes and together with the reinforced concrete in the steel pipes,the composite sections of the piles that are to jointly bear the loads and are cost-saving and rational are formed.The pier shafts are formed by the precast segments.The segments are installed at the site and are connected each other by the φ75 mm thick prestressing bars.The steel box girders are of the optimized streamlined flat sections topped with the orthotropic steel deck plates and the fatigue performance of the girders are quite superior.The stay cables are the ones made up of the parallel steel wires and having tensile strength of 1 860 MPa.%港珠澳大桥青州航道桥为双塔双索面钢箱梁斜拉桥,该桥设计采用了多项新材料、新技术

  7. RISK LEVEL ANALYSIS ON THE PREVENTIVE EROSION CAPACITY OF BRIDGES

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Deficiency of the Preventive Erosion Capacity (PEC) of a bridge pier is the main factor leading to bridge failures. In this paper, the PEC of bridge piers was analyzed using the stochastic analysis method. The definitions of the reliability and risk level of a bridge pier subjected to water erosion were proposed and a computational model for erosion depth and risk level in was suggested.

  8. 46 CFR 72.05-10 - Type, location, and construction of fire control bulkheads and decks.

    Science.gov (United States)

    2010-10-01

    ..., location, and construction of fire control bulkheads and decks. (a) The hull, structural bulkheads, decks... scantlings. (b) The hull, superstructure, and deck houses shall be subdivided by suitable structural steel or... Stairway and elevator enclosures Corridors Life boat embarkation or lowering stations Staterooms and all...

  9. 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.

  10. 49 CFR 176.205 - Under deck stowage requirements.

    Science.gov (United States)

    2010-10-01

    ... ventilated cargo space with no source of artificial heat and clear of living quarters. No bulkhead or deck of... crushing by cargo being stowed against it. (4) Except when fitted with electrical fixtures of the explosion... have been removed from the hold or compartment. Explosion-proof portable lighting may be used if...

  11. Calibrated hot deck imputation for numerical data under edit restrictions

    NARCIS (Netherlands)

    de Waal, A.G.; Coutinho, Wieger; Shlomo, Natalie

    2017-01-01

    We develop a non-parametric imputation method for item non-response based on the well-known hot-deck approach. The proposed imputation method is developed for imputing numerical data that ensure that all record-level edit rules are satisfied and previously estimated or known totals are exactly prese

  12. Meeting Mathematics Standards with a Deck of Playing Cards

    Science.gov (United States)

    McAllister, Deborah A.; McDonald, Shirley A.; Bothman, Susan M.

    2010-01-01

    The activities contained in this document have been presented at several conference sessions. Participants engaged in hands-on activities for Grades 3 through 8 that utilized a deck of playing cards to meet mathematics content and process standards. Activities included variations of card games, but with a mathematical twist, and other card-based…

  13. Modeling of cable vibration effects of cable-stayed bridges

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    The analysis of dynamic responses of cable-stayed bridges subjected to wind and earthquake loads generallyconsiders only the motions of the bridge deck and pylons. The influence of the stay cable vibration on the responses of the bridgeis either ignored or considered by approximate procedures. The transverse vibration of the stay cables, which can be significant insome cases, are usually neglected in previous research. In the present study, a new three-node cable element has been developed tomodel the transverse motions of the cables. The interactions between the cable behavior and the other parts of the bridgesuperstructure are considered by the concept of dynamic stiffness. The nonlinear effect of the cable caused by its self-weight isincluded in the formulation. Numerical examples are presented to demonstrate the accuracy and efficiency of the proposed model.The impact of cable vibration behavior on the dynamic characteristics of cable-stayed bridges is discussed.

  14. Fatigue in Steel Highway Bridges under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, Jette Andkjær

    1999-01-01

    Fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis. In the experimental part of the investigation, fatigue test series on welded plate test specimens...... correspond to one week's traffic loading, determined by means of strain gauge measurements on the orthotropic steel deck structure of the Faro Bridges in Denmark. The test series carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...... the fracture mechanics analysis and the fatigue test results indicate that Miner's rule, which is normally used in the design against fatigue in steel bridges, may give results that are unconservative. The validity. of the results obtained from Miner's rule will depend on the distribution of the load history...

  15. Fatigue in Steel Highway Bridges under Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, J.A.; Vejrum, Tina

    1997-01-01

    In the present investigation, fatigue damage accumulation in steel highway bridges under random loading is studied. The fatigue life of welded joints has been determined both experimentally and from a fracture mechanics analysis.In the experimental part of the investigation, fatigue test series...... to one week's traffic loading, determined by means of strain gage measurements on the orthotropic steel deck structure of the Farø Bridges in Denmark.The test series which have been carried through show a significant difference between constant amplitude and variable amplitude fatigue test results. Both...... the fatigue test results and the fracture mechanics analysis indicate that the linear fatigue damage accumulation formula, which is normally used in the design against fatigue in steel bridges, may give results, which are unconservative. The validity of the results obtained from the linear fatigue damage...

  16. The Damage Effects in Steel Bridges under Highway Random Loading

    DEFF Research Database (Denmark)

    Agerskov, Henning; Nielsen, Jette Andkjær

    1996-01-01

    In the present investigation, fatigue damage accumulation in steel bridges under highway random loading is studied. In the experimental part of the investigation, fatigue test series on welded plate test specimens have been carried through. The fatigue tests have been carried out using load...... histories, which correspond to one week's traffic loading, determined by means of strain gage measurements on the orthotropic steel deck structure of the Farø Bridges in Denmark. Both the results that have been obtained in the test series carried through and the results of fracture mechanics analysis...... indicate that the linear fatigue damage accumulation formula, which is normally used in the design against fatigue in steel bridges, may give results, which are unconservative....

  17. 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.

  18. 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

  19. Full Scale Investigation of the Dynamic Heat Storage of Concrete Decks with PCM and Enhanced Heat Transfer Surface Area

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

    2013-01-01

    of hollow core decks with different surfaces on the bottom are investigated: reference deck made of standard concrete and flat surface, deck with special mortar grooved tiles, deck with flat mortar tiles, deck with grooved mortar and phase change material tiles, deck with flat mortar and phase change...... material tiles. The experimental investigation presented in the paper is performed in the specially designed modified hot box apparatus that allows maintaining periodic steady-state tests with the full-scale concrete deck elements. The presented research investigates if the extended surface area and PCM...

  20. Flexible concrete link slabs used as expansion joints in bridge decks

    DEFF Research Database (Denmark)

    Lárusson, Lárus Helgi; Fischer, Gregor

    2011-01-01

    of water through the expansion joint and subsequent corrosion of girders and girder bearings. Investigations on joint-less superstructures using conventional steel reinforcement in so-called concrete link slabs indicate improved performance and economic feasibility. However, this concept requires...

  1. Strength of Loop Connections between Precast Bridge Decks Loaded in Combined Tension and Bending

    DEFF Research Database (Denmark)

    Jørgensen, Henrik Brøner; Hoang, Linh Cao

    2015-01-01

    The paper presents a study of the load-carrying capacity of loop connections subjected to combined tension and bending. For such connections, the main design challenge in practice is to obtain a load-carrying capacity that is governed by yielding of the looped reinforcing bars (i.e., the U...

  2. Internal Force Calculation of Long Cantilever Traffic Deck Slab%长悬臂行车道板的内力计算

    Institute of Scientific and Technical Information of China (English)

    孙立刚

    2012-01-01

    采用沙柯公式、贝达巴赫公式和Ansys计算分析公路桥梁长悬臂行车道板的内力,总结了计算方法,对设计工作具有一定的参考价值。%Internal force of long cantilever traffic deck slab of highway bridge is calculated and analyzed by the adoption of Sawko formula,Baider Bahkt formula,and Ansys.Calculation methods are summarized which have certain reference value for design effort.

  3. Finite-element (FE modelling of bridge dynamics from exposure to moving load

    Directory of Open Access Journals (Sweden)

    G.M. Kadisov

    2013-12-01

    Full Text Available Solutions to the problem of cable-stayed bridge dynamics are received and analysed on the basis of two modelling options. According to the first one space-time finite-elements are used. The first three bridge vibration modes are shown to study cable-stayed bridge fluctuations when exposed to the vertical force moving at a constant speed and compile charts of time history strains in fixed sections of a deck. According to the second option a suspended superstructure is represented by a fold with absolutely rigid transverse membranes in joints of cables, a bridge tower is represented by a beam. Natural modes of the bridge are received by a solution of homogeneous system equations of the mixed method. Nodal lines of a fold for the first four natural modes are shown. The comparative description of applicability of the above-mentioned methods of solving problems of dynamics affected by moving load is given.

  4. 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.

  5. International Contribution to the Highway Agency's Bridge Related Research

    DEFF Research Database (Denmark)

    Nowak, A. S.; Thoft-Christensen, Palle

    The objective of this paper is to summarize recent contributions of international experts to the research program sponsored by the Highways Agency. An efficient management of existing bridges requires methodology for an accurate evaluation of the actual loads and load carrying capacity and predic......The objective of this paper is to summarize recent contributions of international experts to the research program sponsored by the Highways Agency. An efficient management of existing bridges requires methodology for an accurate evaluation of the actual loads and load carrying capacity...... of reliability models for analysis of bridges subjected to corrosion and fatigue, and reliability-based optimization of maintenance strategies for bridges....

  6. 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.

  7. Robotics and Automation for Flight Deck Aircraft Servicing

    Energy Technology Data Exchange (ETDEWEB)

    Chesser, J.B.; Draper, J.V.; Pin, F.G.

    1999-03-01

    One of the missions of the Future Aircraft Carriers Program is to investigate methods that would improve aircraft turnaround servicing activities on carrier decks. The major objectives and criteria for evaluating alternative aircraft servicing methods are to reduce workload requirements, turnaround times (TAT), and life-cycle costs (LCC). Technologies in the field of Robotics and Automation (R and A) have the potential to significantly contribute to these objectives. The objective of this study was to investigate aircraft servicing functions on carrier decks which would offer the potentially most significant payoff if improved by various R and A technologies. Improvement in this case means reducing workload, time and LCC. This objective was accomplished using a ''bottom-up'' formalized approach as described in the following.

  8. In-service performance and behavior characterization of the hybrid composite bridge system - a case study

    CERN Document Server

    Civitillo, John M; Gheitasi, Amir; Saliba, Mark; Kassner, Bernard L

    2014-01-01

    The Hybrid Composite Beam (HCB) system is an innovative structural technology that has been recently used in bridge construction within the U.S. transportation network. In this system, the superstructure consists of a conventional reinforced concrete deck supported by Hybrid Composite Beams. Each beam is comprised of a glassfiber reinforced polymer (FRP) box shell containing a tied parabolic concrete arch. Inclined stirrups provide shear integrity and enforce composite action between the HCBs and the concrete deck. This paper focuses on evaluating the in-service performance of a newly constructed HCB bridge superstructure located on Route 205 in Colonial Beach, Virginia. A live load test was conducted using tandem axle dump trucks under both quasi-static and dynamic conditions. Results obtained from the experimental investigation were used to determine three key behavior characteristics. Dynamic amplification and lateral load distribution were found to be reasonable in comparison to the assumed design values....

  9. Numerical Hybrid Simulation Modeling Verification for a Curved 3-Pier Bridge (Investigation of Combined Actions on Reinforced Concrete Bridge Piers (CABER Project

    Directory of Open Access Journals (Sweden)

    Adel Abdelnaby

    2013-06-01

    Full Text Available Reinforced concrete bridge piers are subjected to complex loading conditions under earthquake ground motions. Bridge geometric irregularities and asymmetries result in combined actions imposed on the piers as a combination of displacements and rotations in all six degrees of freedom at the pier-deck juncture. Existing analytical tools have proven their inadequacy in representing the actual behavior of piers under these combined actions, particularly in their inelastic range. The objective of this investigation is to develop a fundamental understanding of the effects of these combined actions on the performance of RC piers and the resulting system response. This paper describes a part of the CABER project that verifies the numerical hybrid simulation of the curved bridge. In this part two models were introduced, a whole model and a sub-structured hybrid model. The whole model was established using the Zeus-NL analysis platform, which is capable of performing inelastic nonlinear response history analysis of the whole curved bridge. The hybrid model was divided into three modules which comprised the deck, left and right piers, and the middle pier of the bridge. The three modules were modeled by Zeus-NL as a static analysis module interface. The simulation coordinator (SimCor software was utilized to communicate between these modules using a Pseudo-Dynamic time integration scheme. Results obtained from both models were compared and conclusions were drawn.

  10. MEMS reliability

    CERN Document Server

    Hartzell, Allyson L; Shea, Herbert R

    2010-01-01

    This book focuses on the reliability and manufacturability of MEMS at a fundamental level. It demonstrates how to design MEMs for reliability and provides detailed information on the different types of failure modes and how to avoid them.

  11. 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

  12. 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...

  13. 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.

  14. Vibration analysis of concrete bridges during a train pass-by using various models

    Science.gov (United States)

    Li, Qi; Wang, Ke; Cheng, Shili; Li, Wuqian; Song, Xiaodong

    2016-09-01

    The vibration of a bridge must be determined in order to predict the bridge noise during a train pass-by. It can be generally solved with different models either in the time domain or the frequency domain. The computation cost and accuracy of these models vary a lot in a wide frequency band. This study aims to compare the results obtained from various models for recommending the most suitable model in further noise prediction. First, train-track-bridge models in the time domain are developed by using the finite element method and mode superposition method. The rails are modeled by Timoshenko beam elements and the bridge is respectively modeled by shell elements and volume elements. Second, power flow models for the coupled system are established in the frequency domain. The rails are modelled by infinite Timoshenko beams and the bridge is respectively represented by three finite element models, an infinite Kirchhoff plate, and an infinite Mindlin plate model. The vibration at given locations of the bridge and the power input to the bridges through the rail fasteners are calculated using these models. The results show that the shear deformation of the bridge deck has significant influences on the bridge vibration at medium-to-high frequencies. The Mindlin plate model can be used to represent the U-shaped girder to obtain the power input to the bridge with high accuracy and efficiency.

  15. 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.

  16. A probabilistic bridge safety evaluation against floods.

    Science.gov (United States)

    Liao, Kuo-Wei; Muto, Yasunori; Chen, Wei-Lun; Wu, Bang-Ho

    2016-01-01

    To further capture the influences of uncertain factors on river bridge safety evaluation, a probabilistic approach is adopted. Because this is a systematic and nonlinear problem, MPP-based reliability analyses are not suitable. A sampling approach such as a Monte Carlo simulation (MCS) or importance sampling is often adopted. To enhance the efficiency of the sampling approach, this study utilizes Bayesian least squares support vector machines to construct a response surface followed by an MCS, providing a more precise safety index. Although there are several factors impacting the flood-resistant reliability of a bridge, previous experiences and studies show that the reliability of the bridge itself plays a key role. Thus, the goal of this study is to analyze the system reliability of a selected bridge that includes five limit states. The random variables considered here include the water surface elevation, water velocity, local scour depth, soil property and wind load. Because the first three variables are deeply affected by river hydraulics, a probabilistic HEC-RAS-based simulation is performed to capture the uncertainties in those random variables. The accuracy and variation of our solutions are confirmed by a direct MCS to ensure the applicability of the proposed approach. The results of a numerical example indicate that the proposed approach can efficiently provide an accurate bridge safety evaluation and maintain satisfactory variation.

  17. On maintenance strategies of roads and bridges%谈公路桥梁养护对策

    Institute of Scientific and Technical Information of China (English)

    赵文峰

    2015-01-01

    The paper analyzes the meaning and aims of the road and bridge maintenance,illustrates factual maintenance measures of bridges and roads from the bridge beam maintenance,bridge pier maintenance,and deck maintenance,so as to prolong the life of roads and bridges and re-duce the times and cost of the roads and bridge maintenance by the maintenance measures.%分析了公路桥梁养护的意义及目的,从桥梁梁板养护、桥梁墩台养护、桥面铺装养护三方面,阐述了公路桥梁的具体养护措施,以延长公路桥梁的使用年限,减少公路桥梁修复的次数与成本。

  18. Software reliability

    CERN Document Server

    Bendell, A

    1986-01-01

    Software Reliability reviews some fundamental issues of software reliability as well as the techniques, models, and metrics used to predict the reliability of software. Topics covered include fault avoidance, fault removal, and fault tolerance, along with statistical methods for the objective assessment of predictive accuracy. Development cost models and life-cycle cost models are also discussed. This book is divided into eight sections and begins with a chapter on adaptive modeling used to predict software reliability, followed by a discussion on failure rate in software reliability growth mo

  19. DEM simulation of particle flow on a single deck banana screen

    Institute of Scientific and Technical Information of China (English)

    Liu Chusheng; Wang Hong; Zhao Yuemin; Zhao Lala; Dong Hailin

    2013-01-01

    A mathematical study of particle flow on a banana screen deck using the discrete element method (DEM) was presented in this paper.The motion characteristics and penetrating mechanisms of particles on the screen deck were studied.Effects of geometric parameters of screen deck on banana screening process were also investigated.The results show that when the values of inclination of discharge and increment of screen deck inclination are 10° and 5° respectively,the banana screening process get a good screening performance in the simulation.The relationship between screen deck length and screening efficiency was further confirmed.The conclusion that the screening efficiency will not significantly increase when the deck lengthL ≥430 mm (L/B ≥3.5) was obtained,which can provide theoretical basis for the optimization of banana screen.

  20. Golden Gate Bridge response: a study with low-amplitude data from three earthquakes

    Science.gov (United States)

    Celebi, Mehmet

    2012-01-01

    The dynamic response of the Golden Gate Bridge, located north of San Francisco, CA, has been studied previously using ambient vibration data and finite element models. Since permanent seismic instrumentation was installed in 1993, only small earthquakes that originated at distances varying between ~11 to 122 km have been recorded. Nonetheless, these records prompted this study of the response of the bridge to low amplitude shaking caused by three earthquakes. Compared to previous ambient vibration studies, the earthquake response data reveal a slightly higher fundamental frequency (shorter-period) for vertical vibration of the bridge deck center span (~7.7–8.3 s versus 8.2–10.6 s), and a much higher fundamental frequency (shorter period) for the transverse direction of the deck (~11.24–16.3 s versus ~18.2 s). In this study, it is also shown that these two periods are dominant apparent periods representing interaction between tower, cable, and deck.

  1. Parametrically excited oscillation of stay cable and its control in cable-stayed bridges

    Institute of Scientific and Technical Information of China (English)

    孙炳楠; 汪至刚; 高赞明; 倪一清

    2003-01-01

    This paper presents a nonlinear dynamic model for simulation and analysis of a kind of parametrically excited vibration of stay cable caused by support motion in cable-stayed bridges. The sag, inclination angle of the stay cable are considered in the model, based on which, the oscillation mechanism and dynamic response characteristics of this kind of vibration are analyzed through numerical calculation. It is noted that parametrically excited oscillation of a stay cable with certain sag, inclination angle and initial static tension force may occur in cable-stayed bridges due to deck vibration under the condition that the natural frequency of a cable approaches to about half of the first model frequency of the bridge deck system. A new vibration control system installed on the cable anchorage is proposed as a possible damping system to suppress the cable parametric oscillation. The numerical calculation results showed that with the use of this damping system, the cable oscillation due to the vibration of the deck and/or towers will be considerably reduced.

  2. Numerical Analysis of Heat Storage and Heat Conductivity in the Concrete Hollow Core Deck Element

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund;

    2011-01-01

    the overall heat transfer and heat storage in the hollow-core decks. The presented results allow comparison between detailed results from 2D-COMSOL simulations and simple 1D calculations from the whole building simulation tool such as BSim program and moreover, it is possible to validate the calculation...... method in BSim for the concrete deck element with air voids. Finally, this paper presents a comparison of the calculated heat conductivity of the hollow-core concrete deck and the measured heat conductivity for the same deck by using hot box apparatus....

  3. Requirements for an Aircraft Carrier Flight Deck Fire Fighting Test Facility

    Science.gov (United States)

    2007-11-02

    PEO Carriers 614 Sicard Street SE Stop 7007 11. SPONSOR / MONITOR’S REPORT Washington Navy Yard DC 20376-7007 NUMBER(S) 12. DISTRIBUTION /AVAILABILITY...nozzles are installed every 8 feet (alternately 5 feet and 3 feet apart). > Every point on the flight deck must be reachable by a minimum of two AFFF...nozzle rated at 125 gpm. > AFFF solution flow rates for each flight deck demand point are as follows: AFFF System Nominal Flow Rate Flush Deck/Deck Edge

  4. Identification of aeroelastic forces on bridge cables from full-scale measurements

    DEFF Research Database (Denmark)

    Acampora, Antonio; Macdonald, J.H.G.; Georgakis, Christos

    2011-01-01

    Despite much research in recent years, large amplitude vibrations of inclined cables continue to be of concern for cable-stayed bridges. Various mechanisms have been suggested for their excitation, including rain-wind excitation, dry inclined cable galloping, high reduced velocity vortex shedding...... Bridge. The system records wind conditions and weather conditions, as well as accelerations of certain cables and a few locations on the deck and tower. Using state-of-the-art methods of output-only system identification, the vibration modes of the cables have been identified. From these modes...

  5. Nonlinear Analysis of Cable Vibration of a Multispan Cable-Stayed Bridge under Transverse Excitation

    OpenAIRE

    Kun Lin; Dujian Zou; Minghai Wei

    2014-01-01

    The nonlinear vibrations of cable in a multispan cable-stayed bridge subjected to transverse excitation are investigated. The MECS (multielements cable system) model, where multielements per cable stay are used, is built up and used to analyze the model properties of the multispan cable-stayed bridges. Then, a simplified two-degrees-of-freedom (2-DOFs) model, where the tower or the deck is reduced to a beam, is proposed to analyze the nonlinear dynamic behaviors of the beam and cable. The res...

  6. Lyapunov-Based Control for Suppression of Wind-Induced Galloping in Suspension Bridges

    Directory of Open Access Journals (Sweden)

    Naif B. Almutairi

    2011-01-01

    Full Text Available This paper investigates the suppression of galloping in a suspension bridge due to wind loads. The galloping phenomenon can be destructive due to the high-amplitude oscillations of the structure. Two controllers are proposed to generate the control force needed to suppress the vertical galloping in the suspended cables and in the bridge deck. SIMULINK software is used to simulate the controlled system. The simulation results indicate that the proposed controllers work well. In addition, the performance of the system with the proposed controllers is compared to the performance of the system controlled with a tuned mass damper.

  7. Identification of aeroelastic forces on bridge cables from full-scale measurements

    DEFF Research Database (Denmark)

    Acampora, Antonio; Macdonald, J.H.G.; Georgakis, Christos

    2011-01-01

    Despite much research in recent years, large amplitude vibrations of inclined cables continue to be of concern for cable-stayed bridges. Various mechanisms have been suggested for their excitation, including rain-wind excitation, dry inclined cable galloping, high reduced velocity vortex shedding...... Bridge. The system records wind conditions and weather conditions, as well as accelerations of certain cables and a few locations on the deck and tower. Using state-of-the-art methods of output-only system identification, the vibration modes of the cables have been identified. From these modes...

  8. 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.

  9. Improving Power Converter Reliability

    DEFF Research Database (Denmark)

    Ghimire, Pramod; de Vega, Angel Ruiz; Beczkowski, Szymon

    2014-01-01

    The real-time junction temperature monitoring of a high-power insulated-gate bipolar transistor (IGBT) module is important to increase the overall reliability of power converters for industrial applications. This article proposes a new method to measure the on-state collector?emitter voltage...... of a high-power IGBT module during converter operation, which may play a vital role in improving the reliability of the power converters. The measured voltage is used to estimate the module average junction temperature of the high and low-voltage side of a half-bridge IGBT separately in every fundamental...... is measured in a wind power converter at a low fundamental frequency. To illustrate more, the test method as well as the performance of the measurement circuit are also presented. This measurement is also useful to indicate failure mechanisms such as bond wire lift-off and solder layer degradation...

  10. 桥面铺装黏结材料的制备与性能研究%Preparation and Study of Bonding Material for Deck Overlay

    Institute of Scientific and Technical Information of China (English)

    杨朋; 张肖宁; 吴少鹏

    2008-01-01

    制备并研究了新型桥面黏结材料.选用柔性和耐久性能优越的单组分聚氨酯作为黏结材料,探讨了其与集料的黏结机制.利用优质集料和国际稀浆封层协会微表处技术指南(ISSA A143)中Ⅱ型级配制备出了新型桥面黏结材料.性能研究表明其具有良好的抗拉伸剪切性能、抗疲劳性能和抗水损害性能.该材料是一种性能优良的桥面铺装材料.%A new type bonding material (polyurethane-aggregates mixture) for bridge deck overlay has been prepared and analyzed. One component moisture-curable polyurethane was chosen for binder material because of its excellent flexibility and durability, and then curing mechanism between polyurethane and aggregates was analyzed then. According to ISSA A143 Ⅱ type gradation, polyurethane-aggregate mixture was prepared with selected solidifying mechanism. Experimental results of polyurethane-aggregates mixture show [ that the materid has ] excellent direct tensile and shear properties, fatigue resistance, moisture resistance and flame retardant properties. Polyurethane-aggregates mixture is proved to be an excellent bonding material for bridge deck overlay due to its excellent performance.

  11. Real-time seismic monitoring of the integrated cape girardeau bridge array and recorded earthquake response

    Science.gov (United States)

    Celebi, M.

    2006-01-01

    This paper introduces the state of the art, real-time and broad-band seismic monitoring network implemented for the 1206 m [3956 ft] long, cable-stayed Bill Emerson Memorial Bridge in Cape Girardeau (MO), a new Mississippi River crossing, approximately 80 km from the epicentral region of the 1811-1812 New Madrid earthquakes. The bridge was designed for a strong earthquake (magnitude 7.5 or greater) during the design life of the bridge. The monitoring network comprises a total of 84 channels of accelerometers deployed on the superstructure, pier foundations and at surface and downhole free-field arrays of the bridge. The paper also presents the high quality response data obtained from the network. Such data is aimed to be used by the owner, researchers and engineers to assess the performance of the bridge, to check design parameters, including the comparison of dynamic characteristics with actual response, and to better design future similar bridges. Preliminary analyses of ambient and low amplitude small earthquake data reveal specific response characteristics of the bridge and the free-field. There is evidence of coherent tower, cable, deck interaction that sometimes results in amplified ambient motions. Motions at the lowest tri-axial downhole accelerometers on both MO and IL sides are practically free from any feedback from the bridge. Motions at the mid-level and surface downhole accelerometers are influenced significantly by feedback due to amplified ambient motions of the bridge. Copyright ASCE 2006.

  12. Design and Construction of Operation Bridge for Research Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Kwangsub; Choi, Jinbok; Lee, Jongmin; Oh, Jinho [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2015-05-15

    The operation bridge contains a lower working deck mounted on a saddle that travels on rails. Upright members are mounted on the saddle to support the upper structure and two hoist monorails. The saddle contains an anti-derail system that is composed of seismic lugs and guide rollers. The operation bridge travels along the rails to transport the fuel assembly, irradiated object, and reactor components in the pools by using tools. Hoists are installed at the top girder. The hoist is suspended from the monorail by means of a motor driven trolley that runs along the monorail. Movements of hoist and trolley are controlled by using the control pendant switch. Processes of design and construction of the operation bridge for the research reactor are introduced. The operation bridge is designed under consideration of functions of handling equipment in the pool and operational limits for safety. Structural analysis is carried out to evaluate the structural integrity in the seismic events. Tests and inspections are also performed during fabrication and installation to confirm the function and safety of the operation bridge.

  13. Ground-penetrating radar: A tool for monitoring bridge scour

    Science.gov (United States)

    Anderson, N.L.; Ismael, A.M.; Thitimakorn, T.

    2007-01-01

    Ground-penetrating radar (GPR) data were acquired across shallow streams and/or drainage ditches at 10 bridge sites in Missouri by maneuvering the antennae across the surface of the water and riverbank from the bridge deck, manually or by boat. The acquired two-dimensional and three-dimensional data sets accurately image the channel bottom, demonstrating that the GPR tool can be used to estimate and/or monitor water depths in shallow fluvial environments. The study results demonstrate that the GPR tool is a safe and effective tool for measuring and/or monitoring scour in proximity to bridges. The technique can be used to safely monitor scour at assigned time intervals during peak flood stages, thereby enabling owners to take preventative action prior to potential failure. The GPR tool can also be used to investigate depositional and erosional patterns over time, thereby elucidating these processes on a local scale. In certain instances, in-filled scour features can also be imaged and mapped. This information may be critically important to those engaged in bridge design. GPR has advantages over other tools commonly employed for monitoring bridge scour (reflection seismic profiling, echo sounding, and electrical conductivity probing). The tool doesn't need to be coupled to the water, can be moved rapidly across (or above) the surface of a stream, and provides an accurate depth-structure model of the channel bottom and subchannel bottom sediments. The GPR profiles can be extended across emerged sand bars or onto the shore.

  14. Bridge Management Strategy Based on Extreme User Costs for Bridge Network Condition

    Directory of Open Access Journals (Sweden)

    Ladislaus Lwambuka

    2014-01-01

    Full Text Available This paper presents a practical approach for prioritization of bridge maintenance within a given bridge network. The maintenance prioritization is formulated as a multiobjective optimization problem where the simultaneous satisfaction of several conflicting objectives includes minimization of maintenance costs, maximization of bridge deck condition, and minimization of traffic disruption and associated user costs. The prevalence of user cost during maintenance period is twofold; the first case refers to the period of dry season where normally the traffic flow is diverted to alternative routes usually resurfaced to regain traffic access. The second prevalence refers to the absence of alternative routes which is often the case in the least developed countries; in this case the user cost referred to results from the waiting time while the traffic flow is put on hold awaiting accomplishment of the maintenance activity. This paper deals with the second scenario of traffic closure in the absence of alternative diversion routes which in essence results in extreme user cost. The paper shows that the multiobjective optimization approach remains valid for extreme cases of user costs in the absence of detour roads as often is the scenario in countries with extreme poor road infrastructure.

  15. Optimal, Generic Planning of Maintenance and Inspection of Steel Bridges

    DEFF Research Database (Denmark)

    Sørensen, John Dalsgaard; Faber, M.H.

    2002-01-01

    Fatigue damage is an important deterioration mechanism for steel bridges. This paper describes a simplified and generic approach for reliability and risk based inspection planning of fatigue sensitive structural details. Fatigue sensitive details are categorized according to their loading...

  16. 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.

  17. Flight Deck Weather Avoidance Decision Support: Implementation and Evaluation

    Science.gov (United States)

    Wu, Shu-Chieh; Luna, Rocio; Johnson, Walter W.

    2013-01-01

    Weather related disruptions account for seventy percent of the delays in the National Airspace System (NAS). A key component in the weather plan of the Next Generation of Air Transportation System (NextGen) is to assimilate observed weather information and probabilistic forecasts into the decision process of flight crews and air traffic controllers. In this research we explore supporting flight crew weather decision making through the development of a flight deck predicted weather display system that utilizes weather predictions generated by ground-based radar. This system integrates and presents this weather information, together with in-flight trajectory modification tools, within a cockpit display of traffic information (CDTI) prototype. that the CDTI features 2D and perspective 3D visualization models of weather. The weather forecast products that we implemented were the Corridor Integrated Weather System (CIWS) and the Convective Weather Avoidance Model (CWAM), both developed by MIT Lincoln Lab. We evaluated the use of CIWS and CWAM for flight deck weather avoidance in two part-task experiments. Experiment 1 compared pilots' en route weather avoidance performance in four weather information conditions that differed in the type and amount of predicted forecast (CIWS current weather only, CIWS current and historical weather, CIWS current and forecast weather, CIWS current and forecast weather and CWAM predictions). Experiment 2 compared the use of perspective 3D and 21/2D presentations of weather for flight deck weather avoidance. Results showed that pilots could take advantage of longer range predicted weather forecasts in performing en route weather avoidance but more research will be needed to determine what combinations of information are optimal and how best to present them.

  18. Heat Storage Performance of the Prefabricated Hollow Core Concrete Deck Element with Integrated Microencapsulated Phase Change Material

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

    2012-01-01

    of thermal properties of standard concrete material and pure PCM. Consequently, the numerical models of the decks were updated with the experimentally determined thermal properties of PCM concrete after these two materials have been combined into one material. Finally, the heat storage of the decks......The paper presents the numerically calculated dynamic heat storage capacity of the prefabricated hollow core concrete deck element with and without microencapsulated phase change material (PCM). The reference deck is the ordinary deck made of standard concrete material and that is broadly used...... in many emerging buildings. The new concrete deck with microencapsulated PCM is the standard deck on which one more layer with PCM concrete was added and at the same time the latent heat storage was introduced to the construction. The challenge to simulate the performance of the new deck with PCM concrete...

  19. 46 CFR 108.135 - Boundary bulkheads, decks of galleys, and combustible material lockers.

    Science.gov (United States)

    2010-10-01

    ... material lockers. 108.135 Section 108.135 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED... Protection § 108.135 Boundary bulkheads, decks of galleys, and combustible material lockers. Each boundary... storage locker must be an A class bulkhead and A class deck respectively....

  20. 46 CFR 32.56-15 - Deck spills-T/ALL.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Deck spills-T/ALL. 32.56-15 Section 32.56-15 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY TANK VESSELS SPECIAL EQUIPMENT, MACHINERY, AND HULL....56-15 Deck spills—T/ALL. A coaming or other barrier at least .3 meters (1 foot) higher than adjacent...

  1. STS-56 Commander Cameron and Pilot Oswald on OV-103's forward flight deck

    Science.gov (United States)

    1993-01-01

    During an STS-56 orbiter maneuver, Commander Kenneth Cameron (left), holding checklist, and Pilot Stephen S. Oswald man their respective stations on the forward flight deck of Discovery, Orbiter Vehicle (OV) 103. They are surrounded by forward flight deck windows and forward, center, and overhead control panels. A portable laptop computer is positioned on the forward window sill.

  2. STS-56 Commander Cameron with camera stowage bag on OV-103's flight deck

    Science.gov (United States)

    1993-01-01

    STS-56 Commander Kenneth Cameron, with a penlight flashlight velcroed to his headband, prepares to open a camera stowage bag on the forward flight deck of Discovery, Orbiter Vehicle (OV) 103. Behind him are the forward flight deck windows, forward control panels, and the commanders and pilots seatbacks.

  3. 46 CFR 116.1120 - Drainage of cockpit vessels, well deck vessels, and open boats.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Drainage of cockpit vessels, well deck vessels, and open boats. 116.1120 Section 116.1120 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) SMALL... Drainage of cockpit vessels, well deck vessels, and open boats. Drainage of cockpit vessels, well...

  4. STS-38 Mission Specialist (MS) Springer uses camera on OV-104 aft flight deck

    Science.gov (United States)

    1990-01-01

    STS-38 Mission Specialist (MS) Robert C. Springer, holding HASSELBLAD camera, positions himself under aft flight deck overhead window W7 before recording the Earth's surface below. Behind Springer are Atlantis', Orbiter Vehicle (OV) 104's, onorbit station and aft flight deck viewing windows.

  5. 49 CFR 176.74 - On deck stowage of break-bulk hazardous materials.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false On deck stowage of break-bulk hazardous materials... CARRIAGE BY VESSEL General Handling and Stowage § 176.74 On deck stowage of break-bulk hazardous materials... within a horizontal distance of 25 feet of an operating or embarkation point of a lifeboat. (g)...

  6. Reliability Engineering

    CERN Document Server

    Lazzaroni, Massimo

    2012-01-01

    This book gives a practical guide for designers and users in Information and Communication Technology context. In particular, in the first Section, the definition of the fundamental terms according to the international standards are given. Then, some theoretical concepts and reliability models are presented in Chapters 2 and 3: the aim is to evaluate performance for components and systems and reliability growth. Chapter 4, by introducing the laboratory tests, puts in evidence the reliability concept from the experimental point of view. In ICT context, the failure rate for a given system can be

  7. Flight deck benefits of integrated data link communication

    Science.gov (United States)

    Waller, Marvin C.

    1992-01-01

    A fixed-base, piloted simulation study was conducted to determine the operational benefits that result when air traffic control (ATC) instructions are transmitted to the deck of a transport aircraft over a digital data link. The ATC instructions include altitude, airspeed, heading, radio frequency, and route assignment data. The interface between the flight deck and the data link was integrated with other subsystems of the airplane to facilitate data management. Data from the ATC instructions were distributed to the flight guidance and control system, the navigation system, and an automatically tuned communication radio. The co-pilot initiated the automation-assisted data distribution process. Digital communications and automated data distribution were compared with conventional voice radio communication and manual input of data into other subsystems of the simulated aircraft. Less time was required in the combined communication and data management process when data link ATC communication was integrated with the other subsystems. The test subjects, commercial airline pilots, provided favorable evaluations of both the digital communication and data management processes.

  8. Hygrothermal Performance of West Coast Wood Deck Roofing System

    Energy Technology Data Exchange (ETDEWEB)

    Pallin, Simon B [ORNL; Kehrer, Manfred [ORNL; Desjarlais, Andre Omer [ORNL

    2014-02-01

    Simulations of roofing assemblies are necessary in order to understand and adequately predict actual the hygrothermal performance. At the request of GAF, simulations have been setup to verify the difference in performance between white and black roofing membrane colors in relation to critical moisture accumulation for traditional low slope wood deck roofing systems typically deployed in various western U.S. Climate Zones. The performance of these roof assemblies has been simulated in the hygrothermal calculation tool of WUFI, from which the result was evaluated based on a defined criterion for moisture safety. The criterion was defined as the maximum accepted water content for wood materials and the highest acceptable moisture accumulation rate in relation to the risk of rot. Based on the criterion, the roof assemblies were certified as being either safe, risky or assumed to fail. The roof assemblies were simulated in different western climates, with varying insulation thicknesses, two different types of wooden decking, applied with varying interior moisture load and with either a high or low solar absorptivity at the roof surface (black or white surface color). The results show that the performance of the studied roof assemblies differs with regard to all of the varying parameters, especially the climate and the indoor moisture load.

  9. Hygrothermal Performance of West Coast Wood Deck Roofing System

    Energy Technology Data Exchange (ETDEWEB)

    Pallin, Simon B [ORNL; Kehrer, Manfred [ORNL; Desjarlais, Andre Omer [ORNL

    2014-02-01

    Simulations of roofing assemblies are necessary in order to understand and adequately predict actual the hygrothermal performance. At the request of GAF, simulations have been setup to verify the difference in performance between white and black roofing membrane colors in relation to critical moisture accumulation for traditional low slope wood deck roofing systems typically deployed in various western U.S. Climate Zones. The performance of these roof assemblies has been simulated in the hygrothermal calculation tool of WUFI, from which the result was evaluated based on a defined criterion for moisture safety. The criterion was defined as the maximum accepted water content for wood materials and the highest acceptable moisture accumulation rate in relation to the risk of rot. Based on the criterion, the roof assemblies were certified as being either safe, risky or assumed to fail. The roof assemblies were simulated in different western climates, with varying insulation thicknesses, two different types of wooden decking, applied with varying interior moisture load and with either a high or low solar absorptivity at the roof surface (black or white surface color). The results show that the performance of the studied roof assemblies differs with regard to all of the varying parameters, especially the climate and the indoor moisture load.

  10. Community-based benchmarking of the CMIP DECK experiments

    Science.gov (United States)

    Gleckler, P. J.

    2015-12-01

    A diversity of community-based efforts are independently developing "diagnostic packages" with little or no coordination between them. A short list of examples include NCAR's Climate Variability Diagnostics Package (CVDP), ORNL's International Land Model Benchmarking (ILAMB), LBNL's Toolkit for Extreme Climate Analysis (TECA), PCMDI's Metrics Package (PMP), the EU EMBRACE ESMValTool, the WGNE MJO diagnostics package, and CFMIP diagnostics. The full value of these efforts cannot be realized without some coordination. As a first step, a WCRP effort has initiated a catalog to document candidate packages that could potentially be applied in a "repeat-use" fashion to all simulations contributed to the CMIP DECK (Diagnostic, Evaluation and Characterization of Klima) experiments. Some coordination of community-based diagnostics has the additional potential to improve how CMIP modeling groups analyze their simulations during model-development. The fact that most modeling groups now maintain a "CMIP compliant" data stream means that in principal without much effort they could readily adopt a set of well organized diagnostic capabilities specifically designed to operate on CMIP DECK experiments. Ultimately, a detailed listing of and access to analysis codes that are demonstrated to work "out of the box" with CMIP data could enable model developers (and others) to select those codes they wish to implement in-house, potentially enabling more systematic evaluation during the model development process.

  11. Occupational Issues and Expectations of Turkish Deck Cadets

    Directory of Open Access Journals (Sweden)

    Serdar Yġldġz

    2016-09-01

    Full Text Available Seafaring is one of the world's most difficult professions. Seafarers have to face with many negative factors while they are at sea. These negative factors, makes the seafaring profession difficult to be preferred. Fatigue, stress, heavy weather conditions and lack of communication are some of these factors that affect seafarer’s occupational continuity and also make contribution to occurrence of marine accidents. Cadet is one of the seafarers who will be a navigation officer and captain in the near future. That’s why cadets have a significant role in maritime industry. Theoretical and practical training of cadets is very important. Purpose of this study was to examine deck cadets’ training conditions and difficulties they have to face with during their training period. In order to identify these difficulties, render their lives during trainings easier, and establish their expectations, questionnaire conducted with 618 deck cadets. Interviews were carried out with 3 trainers and 10 maritime companies that have substantial shares in Turkey’s maritime trade. As a result of this study identified factors that increase fatigue mostly, reduction measures have been exposed and have tried to offer solutions. This study is an advisory to improve the occupational continuity of cadets in the profession.

  12. Aspects regarding analysis of the work deck from a support vessel

    Science.gov (United States)

    Axinte, T.; Nutu, C.; Stanca, C.; Cupsa, O.; Carp, A.

    2016-08-01

    The authors are presenting an analysis of the work deck only for the support vessel, a ship having in its structure among others: deck cranes and helicopter deck. The work deck is one of the most important parts of the support vessel's hull. We are starting the paper by presenting the role and the importance of the support vessel's type, by using an original execution drawing carried out using the Unigraphics NX 8.0 Software from Siemens.. Further on we can determine the shear, normal and the von Mises stresses pertaining to the work deck by using the finite element method. After determination of these stresses we can assess fatigue life, strength safety factor and fatigue safety factor. In order to determine the fatigue, the loading pattern only with the full unit cycle will be used. As for determining the safety factor only the ultimate strength stress criterion with the stress type von Mises from failure theories, will be used.

  13. 78 FR 25846 - Special Conditions: Airbus, Model A340-600 Series Airplanes; Lower Deck Crew Rest Compartments

    Science.gov (United States)

    2013-05-03

    ...; Lower Deck Crew Rest Compartments AGENCY: Federal Aviation Administration (FAA), DOT. ACTION: Final... unusual design feature associated with the installation of lower deck crew rest (LDCR) compartments. The... certificate to install a lower deck crew rest (LDCR) compartment in Airbus Model A340-600 series...

  14. 78 FR 21037 - Special Conditions: Airbus Model A330-200 Airplanes; Bulk Cargo Lower Deck Crew Rest Compartments

    Science.gov (United States)

    2013-04-09

    ... Cargo Lower Deck Crew Rest Compartments AGENCY: Federal Aviation Administration (FAA), DOT. ACTION... unusual design feature associated with the installation of bulk cargo lower deck crew rest compartments... supplemental type certificate to install a bulk cargo lower deck crew rest compartment in the Airbus Model...

  15. Material use in the US deck market: an assessment of the market potential for Alaska yellow cedar

    Science.gov (United States)

    I. Eastin; I. Ganguly; S. Shook; A. Brackley

    2005-01-01

    The deck-building industry is going through a period of rapid growth and dramatic change with respect to the types of materials available to build decks. A 2001 study by the Freedonia Group estimates that the demand for decking materials will increase by almost 20 percent between 2000 and 2010. To better understand material use and contractor preferences within the...

  16. 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.

  17. 桥梁施工期暂态结构安全可靠度分析研究%Safety Reliability Analysis of Beam-arch Association Bridge Transient Structure During Construction Period

    Institute of Scientific and Technical Information of China (English)

    王鹏

    2014-01-01

    Transient structure is involved in the process of bridge’s construction.From the perspective of supplementing the results of hazard identification,construction of reliability-based security risk analysis method for transient structure was proposed.Then,the model of transient structure was established to analyze the reliability of transient structure.Thus, identification and analysis method of security risk in the process of bridge’s construction was improved,which provides a new way of analytical control of transient structure.%针对桥梁施工过程中具有施工暂态结构这一特点,从补充危险源识别结果的角度出发,提出基于施工暂态结构可靠指标安全风险分析方法。对连续梁施工暂态结构进行了模型建立和可靠性分析,完善了施工过程安全风险分析方法,为施工暂态结构分析控制提出了一种新的思路。

  18. Pounding Effects in Simply Supported Bridges Accounting for Spatial Variability of Ground Motion: A Case Study

    Directory of Open Access Journals (Sweden)

    G. Tecchio

    2012-01-01

    Full Text Available This study carries out a parametrical analysis of the seismic response to asynchronous earthquake ground motion of a long multispan rc bridge, the Fener bridge, located on a high seismicity area in the north-east of Italy. A parametrical analysis has been performed investigating the influence of the seismic input correlation level on the structural response: a series of nonlinear time history analyses have been executed, in which the variation of the frequency content in the accelerograms at the pier bases has been described by considering the power spectral density function (PSD and the coherency function (CF. In order to include the effects due to the main nonlinear behaviours of the bridge components, a 3D finite element model has been developed, in which the pounding of decks at cap-beams, the friction of beams at bearings, and the hysteretic behaviour of piers have been accounted for. The sensitivity analysis has shown that the asynchronism of ground motion greatly influences pounding forces and deck-pier differential displacements, and these effects have to be accurately taken into account for the design and the vulnerability assessment of long multispan simply supported bridges.

  19. Framework for Bridges Maintenance in Egypt

    Directory of Open Access Journals (Sweden)

    Hesham Abd Elkhalek

    2016-01-01

    Full Text Available The traditional approaches for bridges maintenance is proven to be inefficient as they lead to random way of spending maintenance budget and deteriorating bridge conditions. In many cases, maintenance activities are performed due to user complaints. The objective of this paper is to develop a practical and reliable framework to manage the maintenance and repair activities of Bridges network in Egypt considering performance and budget limits. The model solves an optimization problem that maximizes the average condition of the network given the limited budget using Genetic Algorithm (GA. The main tasks of the system are bridge inventory, condition assessment, deterioration using markov model, and maintenance optimization. The developed model takes into account multiple parameters including serviceability requirements, budget allocation, element importance on structural safety and serviceability, bridge impact on network, and traffic. A questionnaire is conducted to complete the research scope. The proposed model is implemented in software, which provides a friendly user interface. The results of the framework are multi – year maintenance plan for the entire network for up to five years. A case study is presented for validating and testing the model with Data collected from “General Authority for Roads, Bridges and Land Transport” in Egypt.

  20. 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 .

  1. A Bridge Deflection Monitoring with GPS

    Science.gov (United States)

    Figurski, M.; Gałuszkiewicz, M.; Wrona, M.

    2007-01-01

    This paper introduces results of investigation carried on by The Applied Geomatics Section in Military University of Technology. Research includes possibilities of monitoring dynamic behavior of a bridge using high rate GPS data. Whole event was executed with collaboration of The Road and Bridge Management and The Warsaw Geodesy Company. Interdisciplinary approach with this project allows authors to get reliable information about investigating constructions and their respond for true traffic loading detected by GPS receivers. Way of compute data and used software (TRACK) are also shown in this paper.

  2. Integration of energy management concepts into the flight deck

    Science.gov (United States)

    Morello, S. A.

    1981-01-01

    The rapid rise of fuel costs has become a major concern of the commercial aviation industry, and it has become mandatory to seek means by which to conserve fuel. A research program was initiated in 1979 to investigate the integration of fuel-conservative energy/flight management computations and information into today's and tomorrow's flight deck. One completed effort within this program has been the development and flight testing of a fuel-efficient, time-based metering descent algorithm in a research cockpit environment. Research flights have demonstrated that time guidance and control in the cockpit was acceptable to both pilots and ATC controllers. Proper descent planning and energy management can save fuel for the individual aircraft as well as the fleet by helping to maintain a regularized flow into the terminal area.

  3. Flight Deck Interval Management Avionics: Eye-Tracking Analysis

    Science.gov (United States)

    Latorella, Kara; Harden, John W.

    2015-01-01

    Interval Management (IM) is one NexGen method for achieving airspace efficiencies. In order to initiate IM procedures, Air Traffic Control provides an IM clearance to the IM aircraft's pilots that indicates an intended spacing from another aircraft (the target to follow - or TTF) and the point at which this should be achieved. Pilots enter the clearance in the flight deck IM (FIM) system; and once the TTF's Automatic Dependent Surveillance-Broadcast signal is available, the FIM algorithm generates target speeds to meet that IM goal. This study examined four Avionics Conditions (defined by the instrumentation and location presenting FIM information) and three Notification Methods (defined by the visual and aural alerts that notified pilots to IM-related events). Current commercial pilots flew descents into Dallas/Fort-Worth in a high-fidelity commercial flight deck simulation environment with realistic traffic and communications. All 12 crews experienced each Avionics Condition, where order was counterbalanced over crews. Each crew used only one of the three Notification Methods. This paper presents results from eye tracking data collected from both pilots, including: normalized number of samples falling within FIM displays, normalized heads-up time, noticing time, dwell time on first FIM display look after a new speed, a workload-related metric, and a measure comparing the scan paths of pilot flying and pilot monitoring; and discusses these in the context of other objective (vertical and speed profile deviations, response time to dial in commanded speeds, out-of-speed-conformance and reminder indications) and subjective measures (workload, situation awareness, usability, and operational acceptability).

  4. STS-56 Commander Cameron and Pilot Oswald on CCT flight deck in JSC's MAIL

    Science.gov (United States)

    1993-01-01

    STS-56 Discovery, Orbiter Vehicle (OV) 103, Commander Kenneth Cameron, (left) and Pilot Stephen S. Oswald, wearing launch and entry suits (LESs) and launch and entry helmets (LEHs), are seated on the forward flight deck of the crew compartment trainer (CCT), a shuttle mockup. Cameron mans the commander station controls and Oswald the pilots station controls during an emergency egress (bailout) simulation. The view was taken from the aft flight deck looking forward and includes Cameron's and Oswald's profiles and the forward flight deck controls and checklists. The CCT is located in JSC's Mockup and Integration Laboratory (MAIL) Bldg 9NE.

  5. The Deck effect in piN to pipipiN

    Energy Technology Data Exchange (ETDEWEB)

    Jozef Dudek; Adam Szczepaniak

    2005-08-21

    Recent high-statistics analyses of the reaction $\\pi p \\to \\pi \\pi \\pi p$ have motivated a reconsideration of the Deck effect which was widely applied to such data in the 1960's and 70's. The Deck effect is essentially kinematic in origin yet considerable subtleties can arise when one attempts to model its contribution to the data. We will discuss previous Deck studies and propose how it may be constrained further than was possible before using the data now available.

  6. 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

  7. Probabilistic Model of Fatigue Damage in Steel Box-girder Bridge Subject to Stochastic Vehicle Loads%随机车载下钢箱梁桥疲劳损伤概率模型

    Institute of Scientific and Technical Information of China (English)

    罗媛; 颜东煌; 鲁乃唯; 汪勤用

    2016-01-01

    将具有确定性参数的典型疲劳车辆模型改进为随机疲劳车流模型,采用小样本车辆轴重与等效疲劳应力数据拟合响应面的方法解决了车流作用下桥梁有限元应力时程分析耗时过长的问题.提出钢箱梁顶板-U肋疲劳损伤概率建模方法,最后将疲劳损伤概率模型应用于可靠度评估领域,揭示了车流参数对结构疲劳可靠指标的影响规律.研究结果表明:行车道重载车辆的较高占有率是导致其顶板-U肋疲劳可靠指标远低于超车道的重要原因;车辆轴重的增长致使钢箱梁疲劳可靠指标迅速降低,车重年线性增长系数由0增长至1%时,行车道顶板-U肋处100 a的疲劳可靠指标由3.42下降至0.72.随机疲劳车流模型与疲劳损伤概率模型具有一定的应用前景.%The typical fatigue truck model with deterministic parameters is developed to be a stochastic vehicle flow model. The time-consuming problem of bridge finite element analysis under traffic flow loads is solved by using a response surface method to approximate the function between vehicle axle weight of a few training data and equivalent fatigue stresses. A probabilistic fatigue damage modeling method applies to rib-to-deck details of steel box-girder bridges is presented. Finally, the fatigue damage model is applied to the reliability assessment, and the influence of traffic flow parameters on structural fatigue reliability is revealed. The numerical result indicates that (1) the higher occupancy rate of heavy vehicle flow in the slow lane is the main reason for the decrease of the fatigue reliability of corresponding rib-to-deck details compared with the fast lane;(2) the increase of the vehicle axle weight causes a rapid decrease of the fatigue reliability index of the steel box girders, when the annual linear growth factor increases from 0 to 1%, the fatigue reliability index of rib-to-deck detail in the slow lane decreases from 3. 42 to 0. 72 . There is

  8. 钢箱梁桥面板爆炸冲击响应数值模拟研究%Numerical simulation for response of a steel box girder deck to blast loading

    Institute of Scientific and Technical Information of China (English)

    蒋志刚; 白志海; 严波; 朱新明

    2012-01-01

    大跨度缆索承重桥梁遭受恐怖爆炸袭击的风险比一般桥梁大.运用LS-DYNA非线性有限元软件,研究了箱包炸弹和小轿车炸弹(TNT当量10~500 kg)桥面爆炸冲击作用下缆索承重桥梁钢箱梁正交异性桥面板的塑性变形、开裂与破口及耗能.结果表明:桥面板的主要耗能机制为盖板和加劲肋的塑性变形耗能,占爆炸输入能量的70%以上;加劲肋和横隔板对桥面板破口有约束作用,TNT当量为300~500 kg时,纵桥向破口尺寸小于等于横隔板间距,并小于横桥向破口尺寸.%Large span cable-supported bridges suffer greater risk of terrorful explosion than normal bridges do. The plastic deformation, rupture, tearing and energy dissipation of an orthotropic steel deck under blasting loads of hand-placed bombs and sedan bombs (TNT equivalent 10kg-500kg) were investigated with nonlinear finite element software LS-DYNA. The results showed that the bridge decks main energy dissipation mechanisms are the plastic deformation of cover plates and lengthways stiffeners, and the ratio of plastic deformation energy to explosion energy exceeds 70% ; the rupture of deck is constrained by the stiffeners and diaphragms, the lengths of ruptures in lengthways are not longer than the distance between two diaphragms, and shorter than those in width way while TNT equivalent is from 300kg to 500kg.

  9. 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.

  10. 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...

  11. 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....

  12. 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.

  13. Compressive sampling based approach for identification of moving loads distribution on cable-stayed bridges

    Science.gov (United States)

    Bao, Yuequan; Li, Hui; Zhang, Fujian; Ou, Jinping

    2013-04-01

    A moving loads distribution identification method for cable-stayed bridges based on compressive sampling (CS) technique is proposed. CS is a technique for obtaining sparse signal representations to underdetermined linear measurement equations. In this paper, CS is employed to localize moving loads of cable-stayed bridges by limit cable force measurements. First, a vehicle-bridge model for cable-stayed bridges is presented. Then the relationship between the cable force and moving loads is constructed based on the influence lines. With the hypothesis of sparsity distribution of vehicles on bridge deck (which is practical for long-span bridges), the moving loads are identified by minimizing the `l2-norm of the difference between the observed and simulated cable forces caused by moving vehicles penalized by the `l1-norm' of the moving load vector. The resultant minimization problem is convex and can be solved efficiently. A numerical example of a real cable-stayed bridge is carried out to verify the proposed method. The robustness and accuracy of the identification approach with limit cable force measurement for multi-vehicle spatial localization are validated.

  14. 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.

  15. Confiabilidade da mensuração do alinhamento pélvico no plano transverso durante o teste da ponte com extensão unilateral do joelho Reliability of transverse plane pelvic alignment measurement during the bridge test with unilateral knee extension

    Directory of Open Access Journals (Sweden)

    Juliana A. Andrade

    2012-08-01

    the occurrence of musculoskeletal injuries. OBJECTIVES: To investigate the intra- and inter-rater reliability of a qualitative analysis and intra-test reliability of a quantitative analysis of transverse plane pelvic alignment during the bridge test with unilateral knee extension. METHOD: Thirty participants (24.73±4.24 years old were tested. The qualitative analysis was conducted by asking two raters to judge the transverse plane pelvic alignment and its reliability was assessed with the weighted kappa coefficient (k w. The quantitative analysis was conducted by measuring the greatest pelvic tilt angle in transverse plane and its reliability was assessed by use of the intraclass correlation coefficient (ICC; the mean change, which was evaluated using 95% confidence interval of the mean difference (95%CI and Bland-Altman plot; and the quantification of measurement variability, which was assessed using standard error of measurement (SEM and the coefficient of variation of the typical error (CV TE. In addition, the minimal detectable change (MDC95 was determined. RESULTS: The intra-rater reliability ranged from fair to moderate (k w=0.32 to 0.58 and the inter-rater reliability was substantial (k w=0.80. The intra-test reliability was excellent (ICC=0.82, the 95% CI ranged from -0.51º to 1.99º, the SEM was 2.38º and the CV TE was 28.75%. The MDC95 was 6.59º. CONCLUSIONS: The inter-rater reliability was greater than the intra-rater reliability; the intra-test reliability was excellent and showed no systematic or random error.

  16. Microelectronics Reliability

    Science.gov (United States)

    2017-01-17

    convey any rights or permission to manufacture, use, or sell any patented invention that may relate to them. This report was cleared for public release...testing for reliability prediction of devices exhibiting multiple failure mechanisms. Also presented was an integrated accelerating and measuring ...13  Table 2  T, V, F and matrix versus  measured  FIT

  17. Flight Deck of the Future: Virtual Windows and e-textile iGear Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Flight Deck of the Future (F.F) will integrate interdisciplinary talent to design innovative, integrated human interfaces for the next generation of human...

  18. 75 FR 32902 - Wire Decking from the People's Republic of China: Final Affirmative Countervailing Duty...

    Science.gov (United States)

    2010-06-10

    ... (``waterfalls''), depending on the rack storage system. The wire decking may or may not be anchored to the rack... Federal Register. In accordance with section 703(d) of the Act, we subsequently issued instructions to...

  19. Fire modeling for Building 221-T - T Plant Canyon Deck and Railroad Tunnel

    Energy Technology Data Exchange (ETDEWEB)

    Oar, D.L.

    1994-09-29

    This report was prepared by Hughes Associates, Inc. to document the results of fire models for building 221-T Canyon Deck and Railroad Tunnel. Backup data is contained in document No. WHC-SD-CP-ANAL-010, Rev. 0.

  20. Astronaut Russell L. Schweickart on deck prior to water egress training

    Science.gov (United States)

    1968-01-01

    Astronaut Russell L. Schweickart, lunar module pilot of the Apollo 9 (Spacecraft 104/Lunar Module 3/Saturn 504) space mission, relaxes on the deck of the NASA Motor Vessel Retriever prior to water egress training in the Gulf of Mexico.

  1. 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...

  2. 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...

  3. Application of Close Range Photogrammetry to Deck Measurement in Recreational Ships

    OpenAIRE

    Celestino Ordóñez; Belén Riveiro; Pedro Arias; Julia Armesto

    2009-01-01

    In this article, we present results that demonstrate the utility of close range photogrammetry in the measurement of decks in recreational craft as an alternate measurement system to the one based on direct acquisition of coordinates. The areas of deck covered with teakwood for aesthetic or security reasons were measured. Both methods were compared in terms of precision of measurements, time consumption, equipment cost, and ease of manipulation and equipment transportation. Based on the resul...

  4. The five-point bending test applied on wearing courses laid on orthotropic steel decks

    OpenAIRE

    Houel, Adrien; Arnaud, Laurent

    2009-01-01

    This paper deals with the evolving behaviour of wearing courses on steel orthotropic decks, such as the French Millau viaduct bituminous mix or an ultra high performance concrete (UHPC) pavement. This is of great importance when dealing with durability. A five-point bending fatigue test was developed since 2003 at the ENTPE laboratory. It enables to test various bituminous concrete mixes. Recent works on UHPC pavements on steel orthotropic decks are considered to improve service life of such ...

  5. 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

  6. Reactor cover system improvements. Final report FY 1978. [Seal, bearing, support, deck, vessel support

    Energy Technology Data Exchange (ETDEWEB)

    McEdwards, J.A.; Matteras, J.L.

    1978-01-01

    The effort in the reactor cover study area resulted in design recommendations for the vessel support, the deck, and the bearing and seals. Sixteen configurations of bearings and seals were examined as part of this study. The selected concepts use a double inflatable seal plus a sodium dip seal. Six different deck configurations were considered as part of this study. The most attractive of these concepts is the conical deck. Five different vessel support concepts were considered. Of these, the U ring appears to be the most attractive. Significant findings are the following: (1) verified that passive cooling of the deck and support lead to acceptable temperatures; (2) the assembly tolerances can be loosened for lower fabrication cost and easier operation while meeting positional and sealing requirements; (3) determined that the conical deck is the most effective deck configuration; (4) determined that the U ring is the most effective vessel support configuration; (5) selected a bearing and seal approach that gives effective gas sealing, adequate control of sodium frost, and easy maintenance.

  7. Existing bridge evaluation using deficiency point method

    Directory of Open Access Journals (Sweden)

    Vičan Josef

    2016-01-01

    Full Text Available In the transforming EU countries, transportation infrastructure has a prominent position in advancing industry and society. Recent developments show, that attention should be moved from the design of new structures towards the repair and reconstruction of existing ones to ensure and increase their satisfactory structural reliability and durability. The problem is very urgent because many construction projects, especially transport infrastructure, in most European countries are more than 50-60 years old and require rehabilitations based on objective evaluations. Therefore, the paper presents methodology of existing bridge evaluation based on reliability concept using Deficiency Point Method. The methodology was prepared from the viewpoint to determine the priority order for existing bridge rehabilitation.

  8. Theoretical and Experimental Studies of Wave Impact underneath Decks of Offshore Platforms

    Energy Technology Data Exchange (ETDEWEB)

    Baarholm, Rolf Jarle

    2001-07-01

    The main objective of this thesis has been to study the phenomenon of water impact underneath the decks of offshore platforms due to propagating waves. The emphasis has been on the impact loads. Two theoretical methods based on two-dimensional potential theory have been developed, a Wagner based method (WBM) and a nonlinear boundary element method (BEM). A procedure to account for three-dimensional effects is suggested. The deck is assumed to be rigid. Initial studies of the importance of hydroelasticity for wave loads on an existing deck structure have been performed. For a given design wave, the local structural responses were found to behave quasi-static. Global structural response has not been studied. In the Wagner based method gravity is neglected and a linear spatial distribution of the relative impact velocity along the deck is assumed. The resulting boundary value problem is solved analytically for each time step. A numerical scheme for stepping the wetted deck area in time is presented. The nonlinear boundary element method includes gravity, and the exact impact velocity is considered. The incident wave velocity potential is given a priori, and a boundary value problem for the perturbation velocity potential associated with the impact is defined. The boundary value problem is solved for each time step by applying Green's second identity. The exact boundary conditions are imposed on the exact boundaries. A Kutta condition is introduced as the fluid flow reaches the downstream end of the deck. At present, the BEM is only applicable for fixed platform decks. To validate the theories, experiments have been carried out in a wave flume. The experiments were performed in two-dimensional flow condition with a fixed horizontal deck at different vertical levels above the mean free surface. The vertical force on the deck and the wetting of the deck were the primary parameters measured. Only regular propagating waves were applied. When a wave hits the deck, the

  9. Bragg grating fiber optic sensing for bridges and other structures

    Science.gov (United States)

    Measures, Raymond M.; Alavie, A. Tino; Maaskant, Robert; Huang, Shang Yuan; LeBlanc, Michel

    1994-09-01

    We have demonstrated that fiber optic intracore Bragg grating sensors are able to measure the strain relief experienced over an extended period of time by both steel and carbon composite tendons within the concrete deck support girders of a recently constructed two span highway bridge. This is the first bridge in the world to test the prospects of using carbon fiber composite tendons to replace steel tendons. This unique set of measurements was accomplished with an array of 15 Bragg grating fiber optic sensors that were embedded within the precast concrete girders during their construction. We have also demonstrated that these same sensors can measure the change in the internal strain within the girders associated with both static and dynamic loading of the bridge with a truck. We are now studying the ability of Bragg grating fiber optic sensors to measure strong strain gradients and thereby provide a warning of debonding of any Bragg grating sensor from its host structure...one of the most important failure modes for any fiber optic strain sensor.

  10. GPS deflection monitoring of the West Gate Bridge

    Science.gov (United States)

    Raziq, Noor; Collier, Philip

    2007-05-01

    The achievable precision and relatively high sampling rates of currently available GPS receivers are well suited for monitoring the movements of long-span engineering structures where the amplitude of movements is often more than a few centimetres and the frequency of vibrations is low (below 10 Hz). However, engineering structures often offer non-ideal environments for GPS data collection due to high multipath interference and obstructions causing cycle slips in the GPS observations. Also, for many engineering structures such as bridge decks, vertical movements are more pronounced and more structurally critical than horizontal movements. Accuracy of GPS determined positions in the vertical direction is typically two to three times poorer than in the horizontal component. This paper describes the results of a GPS deflection monitoring trial on the West Gate Bridge in Melbourne, Australia. The results are compared to the estimated frequencies and movements from the design of the bridge and previous accelerometer campaigns. The frequency information derived from the GPS results is also compared to frequency data extracted from an accelerometer installed close to a GPS receiver. GPS results agree closely to the historical results and recent accelerometer trials for key modal frequencies. This indicates the suitability of GPS receivers to monitor engineering structures that exhibit smaller movements due to their stiffness and in environments not ideally suited to using GPS.

  11. Comprehensive Bridge Health Evaluation Method Based on Information Fusion

    Directory of Open Access Journals (Sweden)

    Li Li-ping

    2016-01-01

    Full Text Available In the bridge maintenance management decision, the health evaluation on bridge structure is far more than determination of abnormal index exceed fixed threshold, or evaluation on damage status and carrying capacity, the on-site human inspection should also be paid attention. In order to achieve more accurate and reliable health status evaluation result, it needs to take full advantage of various information and parameter. The D-S evidence information fusion was used in the paper to present comprehensive bridge health evaluation method. It fuses bridge operation status using abnormal status identification, bridge durability with residual life estimation, as well as human inspection rating, to arrive at health evaluation. The actual application examples to verify the method is also provided.

  12. 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...

  13. 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

  14. 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.

  15. Formulation of Equations of Motion for a Simply Supported Bridge under a Moving Railway Freight Vehicle

    Directory of Open Access Journals (Sweden)

    Ping Lou

    2007-01-01

    Full Text Available Based on energy approach, the equations of motion in matrix form for the railway freight vehicle-bridge interaction system are derived, in which the dynamic contact forces between vehicle and bridge are considered as internal forces. The freight vehicle is modelled as a multi-rigid-body system, which comprises one car body, two bogie frames and four wheelsets. The bogie frame is linked with the car body through spring-dashpot suspension systems, and the bogie frame is rigidly linked with wheelsets. The bridge deck, together with railway track resting on bridge, is modelled as a simply supported Bernoulli-Euler beam and its deflection is described by superimposing modes. The direct time integration method is applied to obtain the dynamic response of the vehicle-bridge interaction system at each time step. A computer program has been developed for analyzing this system. The correctness of the proposed procedure is confirmed by one numerical example. The effect of different beam mode numbers and various surface irregularities of beam on the dynamic responses of the vehicle-bridge interaction system are investigated.

  16. 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.

  17. Simplified Dynamic Structural Time History Response Analysis of Flexible Approach Walls Founded on Clustered Pile Groups Using Impact_Deck

    Science.gov (United States)

    2016-07-01

    The user assigns a fixed ERDC/ITL TR-16-1 243 damping ratio and Impact_Deck estimates the natural frequencies and calculate the coefficients...for a similar structure. ERDC/ITL TR-16-1 244 I.4 Flexible Wall frequency estimates For the flexible wall problem specified in Appendix C...Impact_Deck example problem . .......................... 39 Table 2.4 Extreme forces/moments for the Impact_Deck example problem

  18. Error Sources in Proccessing LIDAR Based Bridge Inspection

    Science.gov (United States)

    Bian, H.; Chen, S. E.; Liu, W.

    2017-09-01

    Bridge inspection is a critical task in infrastructure management and is facing unprecedented challenges after a series of bridge failures. The prevailing visual inspection was insufficient in providing reliable and quantitative bridge information although a systematic quality management framework was built to ensure visual bridge inspection data quality to minimize errors during the inspection process. The LiDAR based remote sensing is recommended as an effective tool in overcoming some of the disadvantages of visual inspection. In order to evaluate the potential of applying this technology in bridge inspection, some of the error sources in LiDAR based bridge inspection are analysed. The scanning angle variance in field data collection and the different algorithm design in scanning data processing are the found factors that will introduce errors into inspection results. Besides studying the errors sources, advanced considerations should be placed on improving the inspection data quality, and statistical analysis might be employed to evaluate inspection operation process that contains a series of uncertain factors in the future. Overall, the development of a reliable bridge inspection system requires not only the improvement of data processing algorithms, but also systematic considerations to mitigate possible errors in the entire inspection workflow. If LiDAR or some other technology can be accepted as a supplement for visual inspection, the current quality management framework will be modified or redesigned, and this would be as urgent as the refine of inspection techniques.

  19. Torsional and longitudinal vibration of suspension bridge subject to aerodynamic forces

    Directory of Open Access Journals (Sweden)

    Ahmed N. U.

    1998-01-01

    Full Text Available In this paper we consider a dynamic model of suspension bridge governed by a pair of coupled partial differential equations which describe both torsional and longitudinal vibration of the road bed. The vertical and torsional motions are coupled through a nonlinear operation with the nonlinearity arising from loss of tension in the vertical cables supporting the decks. We study the impact of wind forces on the stability of motion of this system both in the absence and presence of viscous and structural damping. The results are illustrated by numerical simulation.

  20. Behaviour of composite sandwich decks at high temperatures

    OpenAIRE

    Puchades, Maria Isabel Garcia

    2016-01-01

    Structures made of FRP composites have been shown to provide efficient and economical applications in bridges and piers. They are being increasingly used due to their several advantages when compared to traditional materials, namely, the lightness, strength, good insulation properties, low maintenance and improved performance when submitted to aggressive environments. However, fire behaviour has been recently identified by several authors as the most critical gap for these materials to be ful...

  1. 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)

  2. 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...

  3. 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...

  4. 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.

  5. 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

  6. 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....

  7. Risk based bridge data collection and asset management and the role of structural health monitoring

    Science.gov (United States)

    Omenzetter, Piotr; Bush, Simon; Henning, Theunis; McCarten, Peter

    2011-04-01

    Bridges are critical to the operation and functionality of the whole road networks. It is therefore essential that specific data is collected regarding bridge asset condition and performance, as this allows proactive management of the assets and associated risks and more accurate short and long term financial planning. This paper proposes and discusses a strategy for collection of data on bridge condition and performance. Recognizing that risk management is the primary driver of asset management, the proposed strategy prioritizes bridges for levels of data collection including core, intermediate and advanced. Individual bridges are seen as parts of wider networks and bridge risk and criticality assessment emphasizes bridge failure or underperformance risk in the network context. The paper demonstrates how more reliable and detailed data can assist in managing network and bridge risks and provides a rationale for application of higher data collection levels for bridges characterized by higher risk and criticality. As the bridge risk and/or criticality increases planned and proactive integration of structural health monitoring (SHM) data into asset management is outlined. An example of bridge prioritization for data collection using several bridges taken from a national highway network is provided using an existing risk and criticality scoring methodology. The paper concludes with a discussion on the role of SHM in data collection for bridge asset management and where SHM can make the largest impacts.

  8. Grid reliability

    CERN Document Server

    Saiz, P; Rocha, R; Andreeva, J

    2007-01-01

    We are offering a system to track the efficiency of different components of the GRID. We can study the performance of both the WMS and the data transfers At the moment, we have set different parts of the system for ALICE, ATLAS, CMS and LHCb. None of the components that we have developed are VO specific, therefore it would be very easy to deploy them for any other VO. Our main goal is basically to improve the reliability of the GRID. The main idea is to discover as soon as possible the different problems that have happened, and inform the responsible. Since we study the jobs and transfers issued by real users, we see the same problems that users see. As a matter of fact, we see even more problems than the end user does, since we are also interested in following up the errors that GRID components can overcome by themselves (like for instance, in case of a job failure, resubmitting the job to a different site). This kind of information is very useful to site and VO administrators. They can find out the efficien...

  9. Structural Reliability of the Tampico Bridge under Wind Loading

    Directory of Open Access Journals (Sweden)

    David de León

    2008-01-01

    Full Text Available Se analiza un puente carretero localizado en Tampico, en la costa este de México, para determinar su confiabilidad estructural ante cargas de viento. Las variabilidades inherentes a las fuerzas aleatorias de viento y a las propiedades mecánicas del acero constituyen las incertidumbres aleatorias, y esto contribuye a la probabilidad de falla de las vigas de acero. La idealización de la carga y la estructura del puente, así como el análisis de la respuesta estructural ante la carga de viento, contribuyen a que exista una incertidumbre adicional, de tipo epistémico, que deriva en un rango (o distribución de posibles probabilidades de falla. El diseño con el mínimo del costo esperado en el ciclo de vida se asocia con el diseño óptimo. Sin embargo, para este diseño óptimo, es posible seleccionar el percentil 90, por ejemplo, (o la media más una desviación estándar de la probabilidad de falla o índice de confiabilidad correspondiente, para administradores con aversión al riesgo, lo cual constituye una decisión conservadora. El criterio propuesto constituye una nueva aproximación para tomar decisiones conservadoras e involucrar a la incertidumbre epistémica en el proceso de diseño y evaluación de puentes

  10. 连续梁与行驶车辆耦合振动分析%Analysis of Coupling Vibration of Continuous Bridge and Moving Vehicle

    Institute of Scientific and Technical Information of China (English)

    陈榕峰; 张建莉

    2014-01-01

    In order to analyze the reciprocity of highway bridge and vehicle ,an analysis method of couple vibration between 1/2-four degree vehicle model and highway bridge deck roughness was advanced .According to the power spectral density function advised by GB/T 7031 -1986 ,the values of different bridge deck roughness were obtained .The samples were taken as the inputting disturbances of a 1/2 vehicle vertical dynamics model .The dynamic response of maximum moment and vertical displacement for the simply-supported beam and the continuous girder in different bridge deck roughness was analyzed by numerical simulation ,and the variety rule of impacting factor was obtained .The result shows that along with the vehicle velocity increasing ,the value of impacting factor first increases and then decreases .But along with the grade of highway bridge deck roughness worse ,the value of impacting factor increases non-linearly .The grade of bridge deck roughness and speed are significant factors of vehicle dynamic effect .%为了分析公路桥梁与车辆之间的相互作用,提出了四自由度1/2车辆模型相对于不平整桥面耦合振动分析方法。根据GB/T 7031-1986建议的公路路面功率谱密度的拟合表达式,求得了不同等级桥面的不平度值,并作为1/2车辆垂向动力学模型的输入激励,基于数值仿真分析,分别对不同等级桥面的连续梁桥进行了控制截面的挠度动力响应计算,得到了相应挠度冲击系数随桥面等级及车速变化规律。结果表明:桥梁挠度冲击系数随车速增加呈先增大后减小趋势;随着公路桥面等级变差,冲击系数呈非线性增大,桥面等级及车速是影响车辆动力作用的显著因素。

  11. Performance-based seismic assessment of skewed bridges with and without considering soil-foundation interaction effects for various site classes

    Science.gov (United States)

    Ghotbi, Abdoul R.

    2014-09-01

    The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and column-bent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center (PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge configurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly

  12. Structural evaluation of a prestressed concrete bridge under an alkali-silica reaction; Evaluacion estructural de un puente de hormigon pretensado afectado por una reaccion alcali-silice

    Energy Technology Data Exchange (ETDEWEB)

    Carpintero Garcia, I.; Bermudez Adriozola, B.

    2010-07-01

    The Central Laboratory of Structures and Materials (CEDEX) was commissioned by the National Department of Highways to evaluate the safety conditions of one bridge built on 1997, which is part of the net of the Spanish National Highways. Even at the first inspection many cracks were detected in the concrete deck, associated with expansion concrete processes. This examination revealed that concrete deterioration was not associated with any reinforcement corrosion process; in fact, there were no symptoms of this pathology all along the bridge. for that reason the internal chemical reactions were considered as the most probable cause for the expansion of concrete, as no symptoms of deterioration due to external attack were found. In order to check the origin of concrete expansion, some tests were carried out on concrete samples drilled on the decks. Results of these tests show that there had been internal reactions in concrete mass which explains its expansion and the appearance of those cracks observed. Further more, some other activities were also carried out on site to estimate the importance of the structural damages, as topographic levelling and dynamic testing of the decks. Also the mechanical properties of concrete probes were tested at laboratory. This article shows the main results obtained on the study carried on to determine the cause and significance of the structural damages of the bridge. (Author) 3 refs.

  13. Quality and reliability management and its applications

    CERN Document Server

    2016-01-01

    Integrating development processes, policies, and reliability predictions from the beginning of the product development lifecycle to ensure high levels of product performance and safety, this book helps companies overcome the challenges posed by increasingly complex systems in today’s competitive marketplace.   Examining both research on and practical aspects of product quality and reliability management with an emphasis on applications, the book features contributions written by active researchers and/or experienced practitioners in the field, so as to effectively bridge the gap between theory and practice and address new research challenges in reliability and quality management in practice.    Postgraduates, researchers and practitioners in the areas of reliability engineering and management, amongst others, will find the book to offer a state-of-the-art survey of quality and reliability management and practices.

  14. Reexamining the validity and reliability of the clinical version of the Iowa gambling task: Evidence from a normal subject group

    Directory of Open Access Journals (Sweden)

    Ching-Hung eLin

    2013-05-01

    Full Text Available Over past decade, the Iowa gambling task (IGT has been utilized to test various decision deficits induced by neurological damage or psychiatric disorders. The IGT has recently been standardized for identifying 13 different neuropsychological disorders. Neuropsychological patients choose bad decks frequently, and normal subjects prefer good EV decks. However, the IGT has several validity and reliability problems. Some research groups have pointed out that the validity of IGT is influenced by the personality and emotional state of subjects. Additionally, several other studies have proposed that the prominent deck B phenomenon (PDB phenomenon – that is, normal subjects preferring bad deck B – may be the most serious problem confronting IGT validity. Specifically, deck B offers a high frequency of gains but negative EV. In the standard IGT administration, choice behavior can be understood with reference to gain-loss frequency (GLF rather than inferred future consequences (EV, the basic assumption of IGT. Furthermore, using two different criteria (basic assumption vs. professional norm results in significantly different classification results. Therefore, we recruited 72 normal subjects to test the validity and reliability of IGT. Each subject performed three runs of the computer-based clinical IGT version. The PDB phenomenon has been observed to a significant degree in the first and second stages of the clinical IGT version. Obviously, validity, reliability and the practice effect were unstable between two given stages. The present form of the clinical IGT version has only one stage, so its use should be reconsidered for examining normal decision makers; results from patient groups must also be interpreted with great care. GLF could be the main factor to be considered in establishing the constructional validity and reliability of the clinical IGT version.

  15. Application of Close Range Photogrammetry to Deck Measurement in Recreational Ships

    Directory of Open Access Journals (Sweden)

    Celestino Ordóñez

    2009-09-01

    Full Text Available In this article, we present results that demonstrate the utility of close range photogrammetry in the measurement of decks in recreational craft as an alternate measurement system to the one based on direct acquisition of coordinates. The areas of deck covered with teakwood for aesthetic or security reasons were measured. Both methods were compared in terms of precision of measurements, time consumption, equipment cost, and ease of manipulation and equipment transportation. Based on the results, we conclude that photogrammetry has advantages in almost every aspect with respect to the direct method. Consequently, photogrammetry is suggested as a suitable method for coordinate measurement of decks in recreational ships. However, in some special circumstances, where ships have wide corridors with few obstacles the direct method can be more appropriate than the photogrammetric method.

  16. Application of close range photogrammetry to deck measurement in recreational ships.

    Science.gov (United States)

    Ordóñez, Celestino; Riveiro, Belén; Arias, Pedro; Armesto, Julia

    2009-01-01

    In this article, we present results that demonstrate the utility of close range photogrammetry in the measurement of decks in recreational craft as an alternate measurement system to the one based on direct acquisition of coordinates. The areas of deck covered with teakwood for aesthetic or security reasons were measured. Both methods were compared in terms of precision of measurements, time consumption, equipment cost, and ease of manipulation and equipment transportation. Based on the results, we conclude that photogrammetry has advantages in almost every aspect with respect to the direct method. Consequently, photogrammetry is suggested as a suitable method for coordinate measurement of decks in recreational ships. However, in some special circumstances, where ships have wide corridors with few obstacles the direct method can be more appropriate than the photogrammetric method.

  17. 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.

  18. Pilot Study for Investigating the Cyclic Response of the Recentering Bridge Bearing System Combined with the Friction Damper

    Directory of Open Access Journals (Sweden)

    Jong Wan Hu

    2016-01-01

    Full Text Available The bridge bearing is one of the component members which provide resting supports between piers and decks. The bridge bearing is intended to control longitudinal movement caused by traffic flow and thermal expansion, thereby reducing stress concentration. In high seismicity area, the bridge bearing has been utilized as the base isolation system to mitigate acceleration transferred from the ground. Although the existing bridge bearing installed between superstructure and substructure provides extra flexibility to the base of the entire structure, considerable permanent deformation occurs due to lack of recentering capacity after earthquake. It is required to spend extra cost for repairing impaired parts. The bridge bearings integrated with superelastic shape memory alloy (SMA devices used for upgrading the recentering effect into the friction damper are proposed in this study. The refined finite element (FE analyses are introduced to reproduce the response of such new structures under cyclic loading condition. The bridge bearing systems that maintain uniform recentering capability are designed with various friction coefficients so as to examine energy dissipation and residual deformation through FE analyses. After observing FE analysis results, optimal design for the recentering bridge bearing system will be proposed to take advantage of energy dissipation and self-centering capacity.

  19. SIMPLIFIED CFD MODAL AND AERODYNAMIC CHARACTERISTICS OF INVERTED TRAPEZOIDAL PLATE-TRUSS DECK%倒梯形板桁主梁CFD简化模型及气动特性研究

    Institute of Scientific and Technical Information of China (English)

    李永乐; 安伟胜; 蔡宪棠; 何庭国

    2011-01-01

    板桁主梁以其良好的整体性和合理的受力性能广泛应用于铁路桥梁建设中,随着桥梁跨径的增大,其抗风性能已逐渐成为控制桥梁设计的关键因素之一.基于桁架受风面积等效,并考虑上流、下流构件间相互的气动干扰,提出了一种简化的CFD分析模型,该模型偏安全地忽略了腹杆和上弦杆、下弦杆连接处相互的气动作用,将三维板桁主梁等效为二维平面结构,从而降低建模难度和减小计算工作量.基于该简化CFD分析模型,对倒梯形板桁主梁的静力气动力系数、涡振性能、颤振导数进行了计算分析,并对比了桥上车辆存在对板桁主梁的气动特性的影响.研究结果表明,倒梯形板桁主梁的涡振性能对雷诺数较为敏感,桥上车辆的存在显著改变了板桁主梁的气动特性.%With its good properties of integrity and reasonable mechanics, the plate-truss deck is gradually widely used in the construction of railway bridges. But its wind-resistant capability becomes one of the important factors controlling the bridge design with the increasing of a bridge span. A simplified CFD modal was presented by the basis of the equivalent trusses area acted by wind. The modal fully consider the aerodynamic interference between the structural members at windward and leeward sides. The modal neglects the aerodynamic interference at the junction of top chords, bottom chords and web members. The three-dimensional plate-truss deck is simplified into a two-dimensional cross section, which can reduce the modeling difficulty and calculation work. The static aerodynamic coefficients, vortex-vibration performance and flutter derivatives of the inverted trapezoidal plate-truss deck are simulated. The influence of train existing on the deck is investigated. The research results show that vortex vibration performance of the inverted trapezoidal plate-truss deck is more sensitive to the Reynolds number, and the existence of

  20. Towards a characterization of information automation systems on the flight deck

    Science.gov (United States)

    Dudley, Rachel Feddersen

    This thesis summarizes research to investigate the characteristics that define information automation systems used on aircraft flight decks and the significant impacts that these characteristics have on pilot performance. Major accomplishments of the work include the development of a set of characteristics that describe information automation systems on the flight deck and an experiment designed to study a subset of these characteristics. Information automation systems on the flight deck are responsible for the collection, processing, analysis, and presentation of data to the flightcrew. These systems pose human factors issues and challenges that must be considered by designers of these systems. Based on a previously developed formal definition of information automation for aircraft flight deck systems, an analysis process was developed and conducted to reach a refined set of information automation characteristics. In this work, characteristics are defined as a set of properties or attributes that describe an information automation system's operation or behavior, which can be used to identify and assess potential human factors issues. Hypotheses were formed for a subset of the characteristics: Automation Visibility, Information Quality, and Display Complexity. An experimental investigation was developed to measure performance impacts related to these characteristics, which showed mixed results of expected and surprising findings, with many interactions. A set of recommendations were then developed based on the experimental observations. Ensuring that the right information is presented to pilots at the right time and in the appropriate manner is the job of flight deck system designers. This work provides a foundation for developing recommendations and guidelines specific to information automation on the flight deck with the goal of improving the design and evaluation of information automation systems before they are implemented.

  1. 46 CFR 108.141 - Boundary bulkheads and decks between the emergency power source and service generators.

    Science.gov (United States)

    2010-10-01

    ... Structural Fire Protection § 108.141 Boundary bulkheads and decks between the emergency power source and... source or components of an emergency electric power source that adjoins a space containing a ship's... 46 Shipping 4 2010-10-01 2010-10-01 false Boundary bulkheads and decks between the emergency power...

  2. Laboratory investigation of fire transfer from exterior wood decks to buildings in the wildland-urban interface

    Science.gov (United States)

    Laura E. Hasburgh; Donald S. Stone; Samuel L. Zelinka

    2017-01-01

    In the wildland-urban interface, wood decks are a target for wildfire and may be ignited by firebrands or flaming debris. Wood decks also present a potential source for ignition of structures in the wildland-urban interface. However, their role in ignition of the adjacent structure is unclear and current regulation is based in part on anecdotal evidence. This paper...

  3. Rolling Deck to Repository III: Shipboard Event Logging

    Science.gov (United States)

    Chandler, C. L.; Arko, R.; Miller, S. P.; Dorsk, A.; McCue, S.; Fisichella, D. C.

    2008-12-01

    Data gathered during NSF-supported scientific research cruises represent an important component of the overall oceanographic data collection. The Rolling Deck to Repository (R2R) pilot project aims to improve access to basic shipboard data and ultimately reduce the work required to provide that access. Improved access will be achieved through identification of best practices for shipboard data management, identification of standard metadata and data products from research cruises, development of metadata schemas to describe a research cruise, and development of a prototype data discovery system that could be used by the entire NSF-supported academic research fleet. Shoreside data managers will work collaboratively with ship technicians and vessel operators to develop approaches that scale from smaller coastal vessels to larger open ocean research vessels. One of the coordinated subprojects within the R2R project will focus on development of a shipboard event logging system that would incorporate best practice guidelines, a metadata schema and new and existing applications to generate a scientific sampling event log in the form of a digital text file. A cruise event logging system enables researchers to record digitally all scientific sampling events and assign a unique event identifier to each entry. Decades of work conducted within large coordinated ocean research programs (JGOFS, GLOBEC, WOCE and RIDGE) have shown that creation of a shipboard sampling event log can facilitate greatly the subsequent integration of data sets from individual investigators. In addition to providing a quick way to determine what types of data might have been collected during a cruise, the sampling event log can be used to visualize the relationship, both temporally and geospatially, between the diverse types of sampling events conducted during a research cruise. Research questions in marine ecology or modeling projects are inherently multi-disciplinary and require access to a variety

  4. 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.

  5. 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.

  6. Reliability of the ultimate strength of ship stiffened panel subjected to random corrosion degradation

    Science.gov (United States)

    Feng, Guo-qing; Hu, Bing-nan; Ren, Hui-long

    2017-03-01

    Attentions have been increasingly paid to the influence of the corrosion on the ultimate strength of ship structures. In consideration of the random characteristics of the corrosion of ship structures, the method for the ultimate strength analysis of the ship stiffened panel structure subjected to random corrosion degradation is presented. According to the measured corrosion data of the bulk carriers, the distribution characteristics of the corrosion data for the stiffened panel on the midship deck are analyzed, and a random corrosion model is established. The ultimate strength of the corroded stiffened panel is calculated by the nonlinear finite element analysis. The statistical descriptions of the ultimate strength of the corroded stiffened panel are defined through the Monte Carlo simulations. A formula is proposed on the ultimate strength reduction of the stiffened panel as a function of the corrosion volume. The reliability analysis of the ultimate strength of the corroded deck stiffened panel is performed. It shows that both the corrosion data of the deck stiffened panel and the ultimate strength of the random corroded deck stiffened panel follow the log-normal distribution. The ultimate stress ratio of the stiffened panel is inversely proportional to the corrosion volume ratio.

  7. 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...

  8. STS-31 crewmembers during simulation on the flight deck of JSC's FB-SMS

    Science.gov (United States)

    1988-01-01

    On the flight deck of JSC's fixed based (FB) shuttle mission simulator (SMS), Mission Specialist (MS) Steven A. Hawley (left), on aft flight deck, looks over the shoulders of Commander Loren J. Shriver, seated at the commanders station (left) and Pilot Charles F. Bolden, seated at the pilots station and partially blocked by the seat's headrest (right). The three astronauts recently named to the STS-31 mission aboard Discovery, Orbiter Vehicle (OV) 103, go through a procedures checkout in the FB-SMS. The training simulation took place in JSC's Mission Simulation and Training Facility Bldg 5.

  9. Fatigue Performance Assessment of Composite Arch Bridge Suspenders Based on Actual Vehicle Loads

    Directory of Open Access Journals (Sweden)

    Bin Chen

    2015-01-01

    Full Text Available In the through arch bridges, the suspenders are the key components connecting the arch rib and the bridge deck in the middle, and their safety is an increasing focus in the field of bridge engineering. In this study, various vehicle traffic flow parameters are investigated based on the actual vehicle data acquired from the long-term structural health monitoring system of a composite arch bridge. The representative vehicle types and the probability density functions of several parameters are determined, including the gross vehicle weight, axle weight, time headway, and speed. A finite element model of the bridge structure is constructed to determine the influence line of the cable force for various suspenders. A simulated vehicle flow, generated using the Monte Carlo method, is applied on the influence lines of the target suspender to determine the stress process, and then the stress amplitude spectrum is obtained based on the statistical analysis of the stress process using the rainflow counting method. The fatigue performance levels of various suspenders are analyzed according to the Palmgren-Miner linear cumulative damage theory, which helps to manage the safety of the suspenders.

  10. Condition Assessment on Thermal Effects of a Suspension Bridge Based on SHM Oriented Model and Data

    Directory of Open Access Journals (Sweden)

    Bo Chen

    2013-01-01

    Full Text Available This paper aims to carry out the condition assessment on temperature distribution and thermal effects of a long span suspension bridge. The structural health monitoring (SHM oriented data analysis is first performed and several indices are developed to process the time-varying temperature, displacement, and strain responses. An analytical procedure based on heat transfer theory is presented to determine the temperature distributions within the bridge. The fine finite element models of the deck plate, the cross frame, and the bridge tower are constructed for thermal analysis. A new approach to the thermal-structural coupling analysis of long span bridges is proposed to examine the structural thermal effects. The feasibility and validity of the proposed data process method and the new approach for thermal-structural coupling analysis are examined through detailed numerical simulation. The numerical results are compared with the field measurement data obtained from the long-term monitoring system of the bridge and they show a very good agreement, in terms of temperature distribution in different time and in different seasons. This exercise verifies the accuracy of the heat transfer analysis employed and the effectiveness and validity of the proposed approaches for data processing and thermal-structural coupling analysis.

  11. Increasing the Capacity of Existing Bridges by Using Unbonded Prestressing Technology: A Case Study

    Directory of Open Access Journals (Sweden)

    Antonino Recupero

    2014-01-01

    Full Text Available External posttensioning or unbonded prestressing was found to be a powerful tool for retrofitting and for increasing the life extension of existing structures. Since the 1950s, this technique of reinforcement was applied with success to bridge structures in many countries, and was found to provide an efficient and economic solution for a wide range of bridge types and conditions. Unbonded prestressing is defined as a system in which the post-tensioning tendons or bars are located outside the concrete cross-section and the prestressing forces are transmitted to the girder through the end anchorages, deviators, or saddles. In response to the demand for a faster and more efficient transportation system, there was a steady increase in the weight and volume of traffic throughout the world. Besides increases in legal vehicle loads, the overloading of vehicles is a common problem and it must also be considered when designing or assessing bridges. As a result, many bridges are now required to carry loads significantly greater than their original design loads; and their deck results still deteriorated by cracking of concrete, corrosion of rebars, snapping of tendons, and so forth. In the following, a case study about a railway bridge retrofitted by external posttensioning technique will be illustrated.

  12. Frontiers of reliability

    CERN Document Server

    Basu, Asit P; Basu, Sujit K

    1998-01-01

    This volume presents recent results in reliability theory by leading experts in the world. It will prove valuable for researchers, and users of reliability theory. It consists of refereed invited papers on a broad spectrum of topics in reliability. The subjects covered include Bayesian reliability, Bayesian reliability modeling, confounding in a series system, DF tests, Edgeworth approximation to reliability, estimation under random censoring, fault tree reduction for reliability, inference about changes in hazard rates, information theory and reliability, mixture experiment, mixture of Weibul

  13. Dynamic Heat Storage and Cooling Capacity of a Concrete Deck with PCM and Thermally Activated Building System

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

    2012-01-01

    the performance of the new deck with PCM concrete is the thermal properties of such a new material, as the PCM concrete is yet to be well defined. The results presented in the paper include models in which the PCM concrete material properties, such as thermal conductivity, and specific heat capacity were first......This paper presents a heat storage and cooling concept that utilizes a phase change material (PCM) and a thermally activated building system (TABS) implemented in a hollow core concrete deck. Numerical calculations of the dynamic heat storage capacity of the hollow core concrete deck element...... with and without microencapsulated PCM are presented. The new concrete deck with microencapsulated PCM is the standard deck on which an additional layer of the PCM concrete was added and, at the same time, the latent heat storage was introduced to the construction. The challenge of numerically simulating...

  14. Experimental Validation of a Numerical Model for Three-Dimensional High-Speed Railway Bridge Analysis by Comparison with a Small-Scale Model

    DEFF Research Database (Denmark)

    Sneideris, J.; Bucinskas, P.; Agapii, L.;

    2015-01-01

    The aim of this paper is to perform dynamic analysis of a multi-span railway bridge interacting with the underlying soil. A small-scale model of a bridge structure is constructed for experimental testing and the results are compared with a computational model. The computational model in this paper...... is based on finite-element analysis for the bridge structure and a semi-analytical solution for the subsoil. The bridge deck and columns are modelled using three-dimensional beam elements. The foundations are implemented as rigid footings placed on the ground surface. The vehicle is modelled as a two...... a passing train. Mattress foam is used to substitute for the subsoil. The model is equipped with a number of accelerometers, strategically placed in certain positions to analyse the dynamic structural response. Finally, the results obtained from experimental tests are used to calibrate and validate...

  15. Experimental study on AR fiberglass connectors for bridges made of composite materials

    Directory of Open Access Journals (Sweden)

    Tolosana, N.

    2006-06-01

    Full Text Available One highly relevant aspect in composite material bridgedesing is the study of the shear connectors to be used.Composite material bridges most commonly comprise acomposite deck resting on steel or reinforced concrete girders.This article analyzes the connectors most frequentlyused in such bridges.It also reviews the connectors used in the King StormwaterChannel Bridge, whose fibreglass deck is supported bygirders made of concrete-filled carbon fibre girders.The paper advances proposals for several types of connectorsand discusses the results of push-out test run ona number of prototypes with different geometries.The results are analyzed to identify the optimum model forthe “Autovia del Cantabrico” Overpass, with its 46-m span,carbon fibre girders and AR glass shear connectors.Un aspecto relevante dentro del proyecto de un puenterealizado en materiales compuestos es el estudio de losconectores. El caso mas frecuente de puente en materialescompuestos es aquel que presenta un tablero de materialescompuestos soportado por vigas metalicas o de hormigonarmado. En este trabajo se analizaran los tipos deconectores mas utilizados en este tipo de puentesSe analizaran tambien los conectores utilizados en elKing Stormwater Channel Bridge, donde ademas deltablero en fibra de vidrio, se fabricaron las vigas en fibrasde carbono rellenas de hormigon.En este articulo se propondran varios tipos de conectoresy se presentaran los resultados experimentales correspondientesal ensayo de “push-out” de varios prototipos condiferentes geometrias.Tras evaluar los resultados, se determinara el mas idoneopara su implantacion en el Paso Superior de la Autovia delCantabrico, de 46 metros de luz y que presenta las vigasen fibra de carbono y los conectores de vidrio AR.

  16. Damage Localization of Cable-Supported Bridges Using Modal Frequency Data and Probabilistic Neural Network

    Directory of Open Access Journals (Sweden)

    X. T. Zhou

    2014-01-01

    Full Text Available This paper presents an investigation on using the probabilistic neural network (PNN for damage localization in the suspension Tsing Ma Bridge (TMB and the cable-stayed Ting Kau Bridge (TKB from simulated noisy modal data. Because the PNN approach describes measurement data in a Bayesian probabilistic framework, it is promising for structural damage detection in noisy conditions. For locating damage on the TMB deck, the main span of the TMB is divided into a number of segments, and damage to the deck members in a segment is classified as one pattern class. The characteristic ensembles (training samples for each pattern class are obtained by computing the modal frequency change ratios from a 3D finite element model (FEM when incurring damage at different members of the same segment and then corrupting the analytical results with random noise. The testing samples for damage localization are obtained in a similar way except that damage is generated at locations different from the training samples. For damage region/type identification of the TKB, a series of pattern classes are defined to depict different scenarios with damage occurring at different portions/components. Research efforts have been focused on evaluating the influence of measurement noise level on the identification accuracy.

  17. Deterministic and Probabilistic Analysis of NPP Communication Bridge Resistance Due to Extreme Loads

    Directory of Open Access Journals (Sweden)

    Králik Juraj

    2014-12-01

    Full Text Available This paper presents the experiences from the deterministic and probability analysis of the reliability of communication bridge structure resistance due to extreme loads - wind and earthquake. On the example of the steel bridge between two NPP buildings is considered the efficiency of the bracing systems. The advantages and disadvantages of the deterministic and probabilistic analysis of the structure resistance are discussed. The advantages of the utilization the LHS method to analyze the safety and reliability of the structures is presented

  18. 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...

  19. IMPLEMENTATION OF DIAGNOSIS AND REPAIR OF BRIDGE STRUCTURES

    Directory of Open Access Journals (Sweden)

    Yushkov Vladimir Sergeevich

    2016-06-01

    Full Text Available Insufficiency and delays of maintenance of the technical state of bridges is greatly related to work labour input, absence of adequate mechanical means and automation of the process of inspection of structures. The authors considered domestic and foreign Machinery which repair bridge structures and are used to conduct surveys, tests and special repairs on different levels, both above and below the vehicle position. The design of a machine with the main operational characteristics is presented. The defects detected during the inspection of bridges are enumerated. In the conditions of deterioration of the bridges of different structures and responding the requirements to reduce the risk level of engineering structures’ operation there is a demand in renewing the population of machines for investigation of the technical condition of automobile bridge, because of special vehicles deterioration, there is no staff of specialists who are able to solve the problems of maintenance and increasing the reliability of bridge structures to the required extend. Also the main principles of control and inspection of bridge structures include the requirements to technical equipment for measurements and testing equipment.

  20. A vibration powered wireless mote on the Forth Road Bridge

    Science.gov (United States)

    Jia, Yu; Yan, Jize; Feng, Tao; Du, Sijun; Fidler, Paul; Soga, Kenichi; Middleton, Campbell; Seshia, Ashwin A.

    2015-12-01

    The conventional resonant-approaches to scavenge kinetic energy are typically confined to narrow and single-band frequencies. The vibration energy harvester device reported here combines both direct resonance and parametric resonance in order to enhance the power responsiveness towards more efficient harnessing of real-world ambient vibration. A packaged electromagnetic harvester designed to operate in both of these resonant regimes was tested in situ on the Forth Road Bridge. In the field-site, the harvester, with an operational volume of ∼126 cm3, was capable of recovering in excess of 1 mW average raw AC power from the traffic-induced vibrations in the lateral bracing structures underneath the bridge deck. The harvester was integrated off-board with a power conditioning circuit and a wireless mote. Duty- cycled wireless transmissions from the vibration-powered mote was successfully sustained by the recovered ambient energy. This limited duration field test provides the initial validation for realising vibration-powered wireless structural health monitoring systems in real world infrastructure, where the vibration profile is both broadband and intermittent.

  1. 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…

  2. 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…

  3. 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,…

  4. 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.

  5. 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...

  6. 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...

  7. 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…

  8. 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)

  9. 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.

  10. STS-39 MS Veach monitors AFP-675 panel on OV-103's aft flight deck

    Science.gov (United States)

    1991-01-01

    STS-39 Mission Specialist (MS) Charles L. Veach analyzes data displayed on Air Force Program 675 (APF-675) command and monitor panel on the aft flight deck payload station aboard Discovery, Orbiter Vehicle (OV) 103. Just above Veach's head, Panel A3 closed circuit television (CCTV) screen A2 glows. At Veach's right is a portable laptop computer attached to panel L10.

  11. STS-27 Pilot Gardner works with cameras on aft flight deck at window W8

    Science.gov (United States)

    1988-01-01

    Pilot Guy S. Gardner holds ARRIFLEX 16mm motion picture camera in his right hand and a 70mm still camera in his left hand as another 70mm camera and a 35mm camera float around him. Gardner tries to position the cameras at aft flight deck overhead window W8.

  12. STS-37 Pilot Cameron and MS Godwin work on OV-104's aft flight deck

    Science.gov (United States)

    1991-01-01

    STS-37 Pilot Kenneth D. Cameron and Mission Specialist (MS) Linda M. Godwin pause from their work on aft flight deck of Atlantis, Orbiter Vehicle (OV) 104, to pose for a picture. Cameron holds onto an onorbit station control panel while Godwin steadies herself by using the overhead window (W8) sill.

  13. Expertise and responsibility effects on pilots' reactions to flight deck alerts in a simulator.

    Science.gov (United States)

    Zheng, Yiyuan; Lu, Yanyu; Yang, Zheng; Fu, Shan

    2014-11-01

    Flight deck alerts provide system malfunction information designed to lead corresponding pilot reactions aimed at guaranteeing flight safety. This study examined the roles of expertise and flight responsibility and their relationship to pilots' reactions to flight deck alerts. There were 17 pilots composing 12 flight crews that were assigned into pairs according to flight hours and responsibilities. The experiment included 9 flight scenarios and was carried out in a CRJ-200 flight simulator. Pilot performance was recorded by a wide angle video camera, and four kinds of reactions to alerts were defined for analysis. Pilots tended to have immediate reactions to uninterrupted cautions, with a turning off rate as high as 75%. However, this rate decreased sharply when pilots encountered interrupted cautions and warnings; they also exhibited many wrong reactions to warnings. Pilots with more expertise had more reactions to uninterrupted cautions than those with less expertise, both as pilot flying and pilot monitoring. Meanwhile, the pilot monitoring, regardless of level of expertise, exhibited more reactions than the pilot flying. In addition, more experienced pilots were more likely to have wrong reactions to warnings while acting as the monitoring pilot. These results suggest that both expertise and flight responsibility influence pilots' reactions to alerts. Considering crew pairing strategy, when a pilot flying is a less experienced pilot, a more experience pilot is suggested to be the monitoring pilot. The results of this study have implications for understanding pilots' behaviors to flight deck alerts, calling for specialized training and design of approach alarms on the flight deck.

  14. STS-26 crew on fixed based (FB) shuttle mission simulator (SMS) flight deck

    Science.gov (United States)

    1988-01-01

    STS-26 Discovery, Orbiter Vehicle (OV) 103, Commander Frederick H. Hauck (left) and Pilot Richard O. Covey review checklists in their respective stations on the foward flight deck. The STS-26 crew is training in the fixed base (FB) shuttle mission simulator (SMS) located in JSC Mission Simulation and Training Facility Bldg 5.

  15. President Nixon on deck of U.S.S. Hornet awaiting Apollo 11 crew arrival

    Science.gov (United States)

    1969-01-01

    President Richard M. Nixon photographed on the deck of the U.S.S. Hornet, prime recovery ship for the Apollo 11 lunar landing mission, awaiting the Apollo 11 crew arrival. swimmer. All four men are wearing biological isolation garments. Apollo 11 splashed down at 11:40 a.m., July 24, 1969, about 812 nautical miles southwest of Hawaii.

  16. STS-38 MS Springer on OV-104's flight deck with Navy banner and Marine decal

    Science.gov (United States)

    1990-01-01

    STS-38 Mission Specialist (MS) Robert C. Springer stretches out in front of the forward flight deck control panels onboard Atlantis, Orbiter Vehicle (OV) 104. Springer poses with a 'Semper Fi United States Marines' decal and a U.S. Naval Academy banner. A HASSELBLAD camera freefloats in front of his chest.

  17. Aces in the Deck: Four Principles for Assessing and Strengthening Student Poems

    Science.gov (United States)

    Morrow, Stephen; Hermsen, Terry

    2008-01-01

    In the late 1970s, poet Lewis MacAdams labeled the many writers beginning to visit schools as "wild cards in the deck of education," bringing fresh possibilities to a somewhat staid curriculum. Now, nearly thirty years later, the authors wonder if it isn't time to renew the metaphor, as everyone strive to name what happens when poets bring their…

  18. On the Effect of Green Water on Deck on the Wave Bending Moment

    DEFF Research Database (Denmark)

    Wang, Zhaohui; Jensen, Jørgen Juncher; Xia, Jinzhu

    1998-01-01

    The aim of the present work is to investigate whether green water on deck in severe sea states have a notable effect on the maximum wave bending moments. The analysis is carried out for an S175 container ship for which results from model experiments are available. The static water head and a mome...

  19. Stacked Deck: An Effective, School-Based Program for the Prevention of Problem Gambling

    Science.gov (United States)

    Williams, Robert J.; Wood, Robert T.; Currie, Shawn R.

    2010-01-01

    School-based prevention programs are an important component of problem gambling prevention, but empirically effective programs are lacking. Stacked Deck is a set of 5-6 interactive lessons that teach about the history of gambling; the true odds and "house edge"; gambling fallacies; signs, risk factors, and causes of problem gambling; and…

  20. STS-26 Commander Hauck poses on shuttle mockup aft flight deck

    Science.gov (United States)

    1988-01-01

    STS-26 Discovery, Orbiter Vehicle (OV) 103, Commander Frederick H. Hauck poses on shuttle mockup aft flight deck in the Shuttle Mockup and Integration Laboratory Bldg 9A. Hauck's right hand is propped on Onorbit Station control panel A2 remote manipulator system (RMS) translation hand control. Photograph was taken by Keith Meyers of the NEW YORK TIMES.

  1. Teaching Random Assignment: A Classroom Demonstration Using a Deck of Playing Cards

    Science.gov (United States)

    Enders, Craig K.; Laurenceau, Jean-Philippe; Stuetzle, Rick

    2006-01-01

    Despite its apparent simplicity, random assignment is an abstract concept for many students. This article describes a classroom demonstration that uses a standard deck of playing cards. In small groups, students randomly assign playing cards (i.e., participants) to 2 treatment groups. Following randomization, students compare the relative…

  2. 46 CFR 32.56-30 - Category A machinery spaces: Bulkheads and decks-T/ALL.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 1 2010-10-01 2010-10-01 false Category A machinery spaces: Bulkheads and decks-T/ALL... EQUIPMENT, MACHINERY, AND HULL REQUIREMENTS Structural Fire Protection for Tank Ships With a Keel Laying Date On or After January 1, 1975 § 32.56-30 Category A machinery spaces: Bulkheads and decks—T/ALL....

  3. Reliability computation from reliability block diagrams

    Science.gov (United States)

    Chelson, P. O.; Eckstein, E. Y.

    1975-01-01

    Computer program computes system reliability for very general class of reliability block diagrams. Four factors are considered in calculating probability of system success: active block redundancy, standby block redundancy, partial redundancy, and presence of equivalent blocks in the diagram.

  4. Simple Program to Investigate Hysteresis Damping Effect of Cross-Ties on Cables Vibration of Cable-Stayed Bridges

    Directory of Open Access Journals (Sweden)

    Panagis G. Papadopoulos

    2012-01-01

    Full Text Available A short computer program, fully documented, is presented, for the step-by-step dynamic analysis of isolated cables or couples of parallel cables of a cable-stayed bridge, connected to each other and possibly with the deck of the bridge, by very thin pretensioned wires (cross-ties and subjected to variation of their axial forces due to traffic or to successive pulses of a wind drag force. A simplified SDOF model, approximating the fundamental vibration mode, is adopted for every individual cable. The geometric nonlinearity of the cables is taken into account by their geometric stiffness, whereas the material nonlinearities of the cross-ties include compressive loosening, tensile yielding, and hysteresis stress-strain loops. Seven numerical experiments are performed. Based on them, it is observed that if two interconnected parallel cables have different dynamic characteristics, for example different lengths, thus different masses, weights, and geometric stiffnesses, too, or if one of them has a small additional mass, then a single pretensioned very thin wire, connecting them to each other and possibly with the deck of the bridge, proves effective in suppressing, by its hysteresis damping, the vibrations of the cables.

  5. 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...

  6. Bienestar Animal: Comportamiento productivo y salud de las crías de cerdos alojadas en tecnología Flat Deck - Animal Well-being: Productive behaviour and health of the breeding of pigs housed in technology Flat Deck

    OpenAIRE

    Maikel Díaz Gutierrez; Yunier Hernández Cruz

    2010-01-01

    ResumenCon el objetivo de evaluar comportamiento productivo y de salud de las crías de cerdos alojados en tecnología Flat Deck se realiza el trabajo Bienestar Animal: Comportamiento productivo y de salud de las crías de cerdos alojadas en tecnología Flat Deck. Para ello se utilizaron 24 bóxer de maternidad de tecnología Flat Deck, de estos 12 de origen chino y 12 de origen español con características similares. Se analizaron un total de 1433 crías mestizas (cruce de hembras Yorkland entre la ...

  7. 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.

  8. 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...

  9. VLSI Reliability in Europe

    NARCIS (Netherlands)

    Verweij, Jan F.

    1993-01-01

    Several issue's regarding VLSI reliability research in Europe are discussed. Organizations involved in stimulating the activities on reliability by exchanging information or supporting research programs are described. Within one such program, ESPRIT, a technical interest group on IC reliability was

  10. 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...

  11. 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)

  12. The stability safety factor calibration based on the reliability index

    Institute of Scientific and Technical Information of China (English)

    Tong Xiaolong; Fang Zhi

    2014-01-01

    When the bridge structure stability safety factor of the first type is 4,the research that whether the structure reliability index will reach target reliability index under the more-likely-to-happen collapse situation of the second type is necessary. The stability calculations of the first and the second type are made respectively for single layer and single span rigid frame bridge. Based on the critical load obtained from the stability calculation of the first type,the stability safety factor of the first type is taken as 4,and the first order reliability method is used to program and calculate the reliability index. Then,the load effect under the stability reliability index cal-culation of the first type and the critical load of the second type are employed to calculate the reliability index of the second type. The evaluation of structure stability safety factor is discussed according to reliability index. Based on the discussion above,parameter analysis of the stable critical loads of two types is made,and the in-fluence of critical load change on reliability index is researched. The result shows that stability analysis should identify collapse state;when the stability safety factor of the first type is 4,but the structure has the collapse of the second type,the reliability index cannot be ensured to reach the target reliability index under certain condi-tions.

  13. The stability safety factor calibration pased on the reliability index

    Institute of Scientific and Technical Information of China (English)

    Tong Xiaolong; Fang Zhi

    2014-01-01

    When the bridge structure stability safety factor of the first type is 4, the research that whether the structure reliability index will reach target reliability index under the more-likely-to-happen collapse situation of the second type is necessary. The stability calculations of the first and the second type are made respectively for single layer and single span rigid frame bridge. Based on the critical load obtained from the stability calculation of the first type, the stability safety factor of the first type is taken as 4, and the first order reliability method is used to program and calculate the reliability index. Then, the load effect under the stability reliability index cal- culation of the first type and the critical load of the second type are employed to calculate the reliability index of the second type. The evaluation of structure stability safety factor is discussed according to reliability index. Based on the discussion above, parameter analysis of the stable critical loads of two types is made, and the in- fluence of critical load change on reliability index is researched. The result shows that stability analysis should identify collapse state; when the stability safety factor of the first type is 4, but the structure has the collapse of the second type, the reliability index cannot be ensured to reach the target reliability index under certain condi- tions.

  14. Effect of sensor placement on operational modal analysis of steel girder bridges

    Science.gov (United States)

    Whelan, Matthew J.; Gangone, Michael V.; Janoyan, Kerop D.

    2011-04-01

    With the advent and development of low-cost wireless structural health monitoring systems, the task of routinely assessing the in-service condition of highway bridges through distributed sensor-based measurements is an increasingly feasible component of bridge safety and management practice. Bridge monitoring encompasses placement of often a limited number of distributed sensors across a relatively large and complex structural system. Consequently, the selection of proper sensor locations is imperative to extraction of the most value from the recorded measurements. An experimental investigation is presented wherein sensor placement on the superstructure girders or primary beams is contrasted to the response measured on the surface of the bridge deck. The effect on the dataset richness, as evidenced by the modal content, is presented and conclusions regarding optimal placement for this structure type are presented. To affirm the plausibility of the observed responses and conclusions drawn, a finite element analysis is also performed on a model developed from the as-built drawings.

  15. Applications of infrared thermography for nondestructive testing of fatigue cracks in steel bridges

    Science.gov (United States)

    Sakagami, Takahide; Izumi, Yui; Kobayashi, Yoshihiro; Mizokami, Yoshiaki; Kawabata, Sunao

    2014-05-01

    In recent years, fatigue crack propagations in aged steel bridge which may lead to catastrophic structural failures have become a serious problem. For large-scale steel structures such as orthotropic steel decks in highway bridges, nondestructive inspection of deteriorations and fatigue damages are indispensable for securing their safety and for estimating their remaining strength. As conventional NDT techniques for steel bridges, visual testing, magnetic particle testing and ultrasonic testing have been commonly employed. However, these techniques are time- and labor- consuming techniques, because special equipment is required for inspection, such as scaffolding or a truck mount aerial work platform. In this paper, a new thermography NDT technique, which is based on temperature gap appeared on the surface of structural members due to thermal insulation effect of the crack, is developed for detection of fatigue cracks. The practicability of the developed technique is demonstrated by the field experiments for highway steel bridges in service. Detectable crack size and factors such as measurement time, season or spatial resolution which influence crack detectability are investigated.

  16. Reliable software for unreliable hardware a cross layer perspective

    CERN Document Server

    Rehman, Semeen; Henkel, Jörg

    2016-01-01

    This book describes novel software concepts to increase reliability under user-defined constraints. The authors’ approach bridges, for the first time, the reliability gap between hardware and software. Readers will learn how to achieve increased soft error resilience on unreliable hardware, while exploiting the inherent error masking characteristics and error (stemming from soft errors, aging, and process variations) mitigations potential at different software layers. · Provides a comprehensive overview of reliability modeling and optimization techniques at different hardware and software levels; · Describes novel optimization techniques for software cross-layer reliability, targeting unreliable hardware.

  17. Ambient Data to Analyse the Dynamic Behaviour of Bridges

    DEFF Research Database (Denmark)

    Brincker, Rune; Stefano, A. de; Piombo, B.

    1996-01-01

    The dynamic analysis of Queensborough bridge data recorded by EDI Ltd., based in Vancouver (Canada), under environmental excitation, is a chance to involve a few different research groups already working in this field. Three different research units have employed alternatives methodologies...... of the results obtained via these techniques in order to select the most reliable aspects and to merge them for creating a common strategy of approaching the bridge monitoring matter. All this, seeking to define an optimum standard methodology to be proposed to those institutions and maintenance companies daily...

  18. Research on Selections of Bridge Site and Type of Hutiaoxia Jinsha River Bridge%虎跳峡金沙江大桥方案研究

    Institute of Scientific and Technical Information of China (English)

    刘伟; 陈克坚; 游励晖

    2013-01-01

    Research purposes:The Hutiaoxia Jinsha River Bridge is the key project of Lijiang-Xianggelila Railway and is located in the sensitive environmental and high seismic intensity region with the active fault.The reasonable bridge site and type should be selected for this bridge on consideration of the railway alignment,environment protection,topography,geological condition and the plan of hydraulic engineering on the midstream of the river.Research conclusions:(1)Using the deck type steel braced arch at the No.8 bridge site(416m) of the Hutaioxia Jinsha River Bridge is the best engineering plan.Using the steel truss suspension bridge at No.27 bridge site (98 + 660 +98 m) can remain the condition for the hydroelectric plan of river and can get the better economic and social benefits.(2) The deck type steel braced arch has features of the good load bearing capacity,good rigidity and nice looking and is suitable for the high mountain and deep valley area,but it produces the impact on the water storage and shipping under bridge because the arch rib is installed on bottom of the structure.(3) The steel truss suspension bridge has the features of the fine anti-seismic performance and good rigidity to meet the train requirement.(4) The research result can provide the reference to the type selection of the large span railway bridge in mountain and deep valley area.%研究目的:虎跳峡金沙江大桥为丽香铁路的重点控制性工程.大桥桥址位于环境敏感区、高烈度地震区及断裂发育带,需要综合线路走线、环保、地形、地质情况及金沙江中游水电开发规划的影响,选择虎跳峡金沙江大桥的合理桥位及桥式方案.研究结论:(1)虎跳峡金沙江大桥的8号桥位416 m上承式钢桁拱桥是最优的工程方案,27号桥位(98+660 +98)m钢桁梁悬索桥可以为规划中的水电开发预留条件,整体上经济、社会效应更好;(2)上承式钢桁拱桥承载能力高、刚度大、造型优美,适用于

  19. 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.

  20. 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...