Stress and noises of steel box girders in Sutong Bridge
Xue Tao; Chen Zhijian; Dong Xuewu
2008-01-01
Sutong Bridge is a cable-stayed bridge with a main span of 1 088 m.370 high-precision stress monitoring measured data show that in the process of hoisting the steel box girders,the stress of the main girders is in the fluctuant and complex state and many meteorological factors,such as sunshine radiation,temperature and wind,have important influence on the change of stress of the steel box girders.According to the real-time weather data,the stress data after the process of wavelet denoising from representative measuring points in different weather conditions is picked to estab-lish the stress response brought by meteorological factors with Layered Separation method,thereby basically eliminating the influence of meteorological factors on the stress of main girders,so that accurate and reliable stress data can be got for steel box girders adjustment and cable-tensioned construction control.
Unconventional Bearing Capacity Analysis and Optimization of Multicell Box Girders
Jovan Tepic
2014-01-01
Full Text Available This study deals with unconventional bearing capacity analysis and the procedure of optimizing a two-cell box girder. The generalized model which enables the local stress-strain analysis of multicell girders was developed based on the principle of cross-sectional decomposition. The applied methodology is verified using the experimental data (Djelosevic et al., 2012 for traditionally formed box girders. The qualitative and quantitative evaluation of results obtained for the two-cell box girder is realized based on comparative analysis using the finite element method (FEM and the ANSYS v12 software. The deflection function obtained by analytical and numerical methods was found consistent provided that the maximum deviation does not exceed 4%. Multicell box girders are rationally designed support structures characterized by much lower susceptibility of their cross-sectional elements to buckling and higher specific capacity than traditionally formed box girders. The developed local stress model is applied for optimizing the cross section of a two-cell box carrier. The author points to the advantages of implementing the model of local stresses in the optimization process and concludes that the technological reserve of bearing capacity amounts to 20% at the same girder weight and constant load conditions.
PARAMETRIC STUDY OF SKEW ANGLE ON BOX GIRDER BRIDGE DECK
Shrikant D. Bobade *, Dr. Valsson Varghese
2016-01-01
Box girder bridge deck, is the most common type of bridges in world and India, it consists of several Slab or girders. The span in the direction of the roadway and connected across their tops and bottoms by a thin continuous structural stab, the longitudinal box girders can be made of steel or concrete. The Simple supported single span concrete bridge deck is presented in present study. Skewed bridges are suitable in highway design when the geometry of straight bridges is not possible. The sk...
Stiffened flanges used in steel box girder bridges
Ferreira, Pedro; Virtuoso, Francisco
2015-01-01
This paper presents a design method for stiffened flanges used in steel box girder bridges based on a set of design curves that take into account all relevant parameters regarding the ultimate strength of stiffened flanges, including the real boundary conditions for the inplane displacements at the edges. These design curves were developed and calibrated based on the results obtained with nonlinear analysis using the semi-analytical and finite element methods and they were vali...
The Influence of Shear Effects on the Deflections of Steel Box Girder Bridges
V. Křístek
2000-01-01
Full Text Available It is already well known that the shear lag phenomenon, generated by shear deformations in the flanges of box girders, can result in a very non-uniform distribution, across the flange width, of longitudinal normal stresses, and consequently can then influence girder deflections. The shear lag effects become even more pronounced in cases where flange width increases in relation to girder span. However, in box girders, where the cross-sectional area of webs usually represents a fraction of the total cross sectional area, also shear deformations of webs can significantly affect the magnitudes of girder deflections. Both these phenomena – the shear lag in the flanges and the shear deformations in the webs – become particularly manifest in box girders subjected to considerable shear forces. Such a situation occurs when a box girder bridge is under the action of usual deal and live loads.
Effect of material uncertainties on dynamic response of segmental box girder bridge
Suchart Limkatanyu; Kittisak Kuntiyawichai
2007-01-01
The main objective of this paper was to investigate the effect of material uncertainties on dynamic response of segmental box girder bridge subjected to a moving load, in this case a rapid passing trains. Literatures concerned with the design of segmental box girder bridge, the application of finite element analysis to model the segmental box girder bridge, and the minimum requirement for structural conditions of the bridge were described and discussed in detail. A series of finite element a...
Design and test of box girder for a large wind turbine blade
Nielsen, Per Hørlyk; Tesauro, Angelo; Bitsche, Robert;
This report is covering the structural design and full scale test of a box girder as a part of the project “Demonstration of new blade design using manufacturing process simulations” supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions......, which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated that the...... manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes...
Tan Manjiang
2015-01-01
Full Text Available To research structural performance of extra-large-span cable-stayed bridge under different section forms, with the engineering background of a 800m main-span cable-stayed bridge with steel truss girder, the cable-stayed bridge with steel box girder is designed according to the current bridge regulations when two bridges are designed in an ultimate state of the carrying capacity, so the maximum stress and minimum stress of the stress envelope diagram are substantially the same. A comprehensive comparison is given to two types of bridge on the aspect of static force, natural vibration frequency, stability, economic performance and so on. Analysis results provide future reference for the large-span cable-stayed bridge to select between the steel truss girder and the steel box girder.
Design and test of box girder for a large wind turbine blade
Nielsen, Per H.; Tesauro, A.; Bitsche, R. [Technical Univ. of Denmark. DTU Wind Energy, DTU Risoe Campus, Roskilde (Denmark)] [and others
2012-09-15
This report is covering the structural design and full scale test of a box girder as a part of the project ''Demonstration of new blade design using manufacturing process simulations'' supported by the EUDP program. A box girder with a predetermined outer geometry was designed using new inventions, which create an inner structure in the box girder. With a combination of advanced FEM analysis and the inventions it was possible to reduce the material thickness of the cap by up to 40%. The new design of the box girder was manufactured at SSP Technology A/S, where it was demonstrated that the manufacturing process could include the new inventions. Subsequently the box girder was transported to the blade test facility at DTU Wind Energy. A series of test was performed with the blade to investigate the behaviour during loading, and finally the girder was loaded to ultimate failure. The report includes the description of the test setup, the test and an overview over the results from the test performed on the box girder. During the final test the box girder failed at 58 % of the expected ultimate load. Unfortunately, no definite conclusion could be made concerning the failure mechanism. (Author)
Dynamic Magnification Factor in a Box-Shape Steel Girder
Rahbar-Ranji, A.
2014-01-01
The dynamic effect of moving loads on structures is treated as a dynamic magnification factor when resonant is not imminent. Studies have shown that the calculated magnification factors from field measurements could be higher than the values specified in design codes. It is the main aim of present paper to investigate the applicability and accuracy of a rule-based expression for calculation of dynamic magnification factor for lifting appliances used in marine industry. A steel box shape girder of a crane is considered and transient dynamic analysis using computer code ANSYS is implemented. Dynamic magnification factor is calculated for different loading conditions and compared with rule-based equation. The effects of lifting speeds, acceleration, damping ratio and position of cargo are examined. It is found that rule-based expression underestimate dynamic magnification factor.
Tan Manjiang; Bai Zhizhou; Chen Dewei
2015-01-01
To research structural performance of extra-large-span cable-stayed bridge under different section forms, with the engineering background of a 800m main-span cable-stayed bridge with steel truss girder, the cable-stayed bridge with steel box girder is designed according to the current bridge regulations when two bridges are designed in an ultimate state of the carrying capacity, so the maximum stress and minimum stress of the stress envelope diagram are substantially the same. A comprehensive...
Design of steel box girder for Taizhou Yangtze River Highway Bridge
Ding Lei; Shan Hongwei; Zhou Qing; Zheng Benhui
2011-01-01
Taizhou Yangtze River Highway Bridge is the first three-pylon two-span suspension bridge in China. The maingirder adopts flat steamline steel closed box girder which has well wind-resistant capability and is technically mature besides beautiful appearance. Straight web plates of the steel box girder in longitudinal direction are proposed in order to ensure the integrity of the steel box girder, and to keep the stress of the steel box girder continuous in the middle pylon,as well as to reduce the gradient of the middle pylon columns. The cross section of the box girder has one box with three cells. Solid-web diaphragm plate with good integrity and high torsional stiffness is adopted. The lifting lugs are utilized in the anchors of suspender cable. In this paper, selection of the cross section of the steel box girder, the general structure design, local structure design and main structure calculation results of Taizhou Yangtze River Bridge are introduced emphatically.
Research on the special lifting devices for steel box girders of Sutong Bridge
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.
Full Scale Test of a SSP 34m box girder 1. Data report
Jensen, Find Mølholt; Branner, Kim; Nielsen, Per Hørlyk;
surface deformation. A prediction was made on the location of the failure of the girder. At this location the majority of the measuring equipment was concentrated. The prediction was proved to be correct and valuable information of the behaviour of the box girder prior to failure was obtained......This report presents the setup and result of a full-scale test of a reinforced glass fibre/epoxy box girder used in 34m wind turbine blade. The tests were performed at the Blaest test facility in August 2006. The test is an important part of a research project established in cooperation between...... the box girder was loaded until failure. A comprehensive description of the test setup is given. This report deals only with tests and results. There are no conclusions on the data in this report, but references are given to publications, where the data are used and compared with FEM etc. Various kinds...
Seismic response of skewed RC box-girder bridges
Ahmed Abdel-Mohti; Gokhan Pekcan
2008-01-01
It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities.Since the 1971 San Fernando earthquake,there has been a better understanding of the seismic performance of bridges.Nonetheless,there are no detailed guidelines addressing the performance of skewed highway bridges.Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex.Therefore,there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges.This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees,analytically.Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000.Different types of analysis were considered on both models such as:nonlinear static pushover,and linear and nonlinear time history analyses.A comparison was conducted between FE and BS,different skew angles,abutment support conditions,and time history and pushover analysis.It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles.Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis.Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.
Dynamic Analysis of Horizontally Curved Thin-Walled Box-Girder Bridge due to Moving Vehicle
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.
Effect of material uncertainties on dynamic response of segmental box girder bridge
Suchart Limkatanyu
2007-11-01
Full Text Available The main objective of this paper was to investigate the effect of material uncertainties on dynamic response of segmental box girder bridge subjected to a moving load, in this case a rapid passing trains. Literatures concerned with the design of segmental box girder bridge, the application of finite element analysis to model the segmental box girder bridge, and the minimum requirement for structural conditions of the bridge were described and discussed in detail. A series of finite element analysis was carried out using SAP2000 Nonlinear software. The effect was investigated by varying the Modulus of Elasticity by 5%, 10% and 15%. The results were then compared with the case of assumed uniform property which had already been checked for model accuracy using the Standard prEN 1991-2. The results showed that, for the uniform case, the dynamic responses of the bridge gave the highest response at the resonance speed. When considering the non-uniform material properties (non-uniform case, the effect of material uncertainties appeared to have an effect on both displacement and acceleration responses. Nonetheless, the dynamic factor provided in the design code was sufficient for designing the segmental box girder bridge with either uniform or non-uniform material properties for the train speeds considered in this study.
Early-age Cracking Control for Diaphragm of Box Girder Bridge with Prestressing Force
Zonglin Wang; Guodong Li
2013-01-01
It presents the results on the early-age cracking control of diaphragm in long-span prestressed concrete box girder bridge with prestressing force. Based on the three-dimensional hydration heat temperature conduction theory and humidity diffusion theory, the early-age cracking mechanism of diaphragm was simulated by finite element model. Meanwhile, the cracking control techniques of prestressing force to prevent the early-age cracking for diaphragm is discussed. The cracking control tec...
Field test on temperature field and thermal stress for prestressed concrete box-girder bridge
Baoguo CHEN; Rui DING; Junjie ZHENG; Shibiao ZHANG
2009-01-01
A field test was conducted to investigate the distribution of temperature field and the variation of thermal stress for a prestressed concrete (PC) box-girder bridge. The change of hydration heat temperature consists of four periods: temperature rising period, constant temperature period, rapid temperature fall period and stow temperature fall period. The peak value of hydration heat temperature increases with the increasing casting temperature of concrete; the relation between them is approximately linear. According to field tests, the thermal stress incurred by hydration heat may induce temperature cracks on the PC box-girder. Furthermore, the nonlinear distribution of temperature gradient and the fluctuation of thermal stress induced by exposure to sunlight were also obtained based on continuous in-situ monitoring. Such results show that the prevailing Chinese Code (2004) is insufficient since it does not take into account the temperature gradient of the bottom slab. Finally, some preventive measures against temperature cracks were proposed based on related studies. The conclusions can provide valuable reference for the design and construction of PC box-girder bridges.
Yan Shiguang; Li Hongtao; Wang Chao
2012-01-01
This article presents in detail the assembling and welding process technique of the steel box girder tuyere blocks of Taizhou Bridge. The application of this process technique effectively solves the problem of welding stress release in tuyere block assembling and welding without increasing the number of turns of the blocks and overhead welding, thus avoiding possible structural deformation due to excessive accumulation of internal welding stress, greatly reducing the repeated deformation and correction work during assembling and welding, and ensuring the weld seam quality and overall dimensions of tuvere blocks of Taizhou Bridze.
Zhengjie Zhou
2010-01-01
Full Text Available Precast, prestressed concrete box girders are commonly used as superstructure components for short and medium span bridges. Their configuration and typical side-by-side placement make large portions of these elements inaccessible for visual inspection or the application of nondestructive testing techniques. This paper demonstrates that vibration-based damage detection (VBDD is an effective alternative for monitoring their structural health. A box girder removed from a dismantled bridge was used to evaluate the ability of five different VBDD algorithms to detect and localize low levels of spalling damage, with a focus on using a small number of sensors and only the fundamental mode of vibration. All methods were capable of detecting and localizing damage to a region within approximately 1.6 times the longitudinal spacing between as few as six uniformly distributed accelerometers. Strain gauges configured to measure curvature were also effective, but tended to be susceptible to large errors in near support damage cases. Finite element analyses demonstrated that increasing the number of sensor locations leads to a proportional increase in localization accuracy, while the use of additional modes provides little advantage and can sometimes lead to a deterioration in the performance of the VBDD techniques.
Fatigue stress monitoring and analyses for steel box girder of Runyang Suspension Bridge
Ying WANG; Zhaoxia LI; Baijian WU
2008-01-01
The monitoring of fatigue stress of steel bridge is a key issue of bridge health monitoring and safety assessment. This paper aims to find out the strain history features of the girder components of Runyang Suspension Bridge (RYSB) under vehicle and environmental loading during its first year of service based on the strain-history data recorded by structural health monitoring system installed in the bridge. The fatigue stress spectrums of steel box girders under normal traffic load, heavy trucks and typhoon loads were studied as well as the correlation between varying strain and temperature based on real-time monitoring of temperature histories. The results show that, monitoring on local strain in health monitoring systems of RYSB can effectively provide the information on fatigue stresses. The range of the equivalent fatigue stress on the monitoring location of the bridge is currently low, mainly due to varying traffic loading and temper-ature. There exists significant correlation between varying temperature and mean value of fatigue stress. Effect of the passing of heavy trucks on bridge fatigue is quite signifi-cant since the value of the cumulative fatigue damage generated by heavy trucks is 10 to 100 times larger than that by normal traffic. Therefore, the effect on fatigue cumulative damage due to heavy trucks or overloaded vehicles needs to be monitored and paid much attention to.
Zheheng Chen; Tong Guo; Shengyou Yan
2015-01-01
Structural health monitoring (SHM) has attracted much attention in recent years, which enables early warnings of structural failure, condition assessments, and rational maintenance/repair strategies. In the context of bridges, many long-span steel bridges in China have been installed with the SHM systems; however, the applications of the SHM in prestressed concrete (PSC) bridges are still rather limited. On the other hand, the PSC box girder bridges are extensively used in highway and railway...
Chen, G. W.; Omenzetter, P.
2016-04-01
This paper presents the implementation of an updating procedure for the finite element model (FEM) of a prestressed concrete continuous box-girder highway off-ramp bridge. Ambient vibration testing was conducted to excite the bridge, assisted by linear chirp sweepings induced by two small electrodynamic shakes deployed to enhance the excitation levels, since the bridge was closed to traffic. The data-driven stochastic subspace identification method was executed to recover the modal properties from measurement data. An initial FEM was developed and correlation between the experimental modal results and their analytical counterparts was studied. Modelling of the pier and abutment bearings was carefully adjusted to reflect the real operational conditions of the bridge. The subproblem approximation method was subsequently utilized to automatically update the FEM. For this purpose, the influences of bearing stiffness, and mass density and Young's modulus of materials were examined as uncertain parameters using sensitivity analysis. The updating objective function was defined based on a summation of squared values of relative errors of natural frequencies between the FEM and experimentation. All the identified modes were used as the target responses with the purpose of putting more constrains for the optimization process and decreasing the number of potentially feasible combinations for parameter changes. The updated FEM of the bridge was able to produce sufficient improvements in natural frequencies in most modes of interest, and can serve for a more precise dynamic response prediction or future investigation of the bridge health.
This paper presents a wireless ultrasonic wavefield imaging (WUWI) technique for detecting hidden damage inside a steel box girder bridge. The proposed technique allows (1) complete wireless excitation of piezoelectric transducers and noncontact sensing of the corresponding responses using laser beams, (2) autonomous damage visualization without comparing against baseline data previously accumulated from the pristine condition of a target structure and (3) robust damage diagnosis even for real structures with complex structural geometries. First, a new WUWI hardware system was developed by integrating optoelectronic-based signal transmitting and receiving devices and a scanning laser Doppler vibrometer. Next, a damage visualization algorithm, self-referencing f-k filter (SRF), was introduced to isolate and visualize only crack-induced ultrasonic modes from measured ultrasonic wavefield images. Finally, the performance of the proposed technique was validated through hidden crack visualization at a decommissioned Ramp-G Bridge in South Korea. The experimental results reveal that the proposed technique instantaneously detects and successfully visualizes hidden cracks even in the complex structure of a real bridge. (paper)
An, Yun-Kyu; Song, Homin; Sohn, Hoon
2014-09-01
This paper presents a wireless ultrasonic wavefield imaging (WUWI) technique for detecting hidden damage inside a steel box girder bridge. The proposed technique allows (1) complete wireless excitation of piezoelectric transducers and noncontact sensing of the corresponding responses using laser beams, (2) autonomous damage visualization without comparing against baseline data previously accumulated from the pristine condition of a target structure and (3) robust damage diagnosis even for real structures with complex structural geometries. First, a new WUWI hardware system was developed by integrating optoelectronic-based signal transmitting and receiving devices and a scanning laser Doppler vibrometer. Next, a damage visualization algorithm, self-referencing f-k filter (SRF), was introduced to isolate and visualize only crack-induced ultrasonic modes from measured ultrasonic wavefield images. Finally, the performance of the proposed technique was validated through hidden crack visualization at a decommissioned Ramp-G Bridge in South Korea. The experimental results reveal that the proposed technique instantaneously detects and successfully visualizes hidden cracks even in the complex structure of a real bridge.
Assessment of seismic performance of skew reinforced concrete box girder bridges
Abdel-Mohti, Ahmed; Pekcan, Gokhan
2013-12-01
The seismic vulnerability of highway bridges remains an important problem and has received increased attention as a consequence of unprecedented damage observed during several major earthquakes. A significant number of research studies have examined the performance of skew bridges under service and seismic loads. The results of these studies are particularly sensitive to modeling assumptions in view of the interacting parameters. In the present study, three-dimensional improved beam-stick models of two-span highway bridges with skew angles varying from 0° to 60° are developed to investigate the seismic response characteristics of skew box girder bridges. The relative accuracy of beam-stick models is verified against counterpart finite element models. The effect of various parameters and conditions on the overall seismic response was examined such as skew angle, ground motion intensity, soil condition, abutment support conditions, bridge aspect ratio, and foundation-base conditions. The study shows that the improved beam-stick models can be used to conduct accurate nonlinear time history analysis of skew bridges. Skew angle and interacting parameters were found to have significant effect on the behavior of skewed highway bridges. Furthermore, the performance of shear keys may have a predominant effect on the overall seismic response of the skew bridges.
Jensen, Find M.; Branner, K.; Nielsen, Per H. (and others)
2008-03-15
This report presents the setup and result of a full-scale test of a reinforced glass fibre/epoxy box girder used in 34m wind turbine blade. The tests were performed at the Blaest test facility in August 2006. The test is an important part of a research project established in cooperation between Risoe DTU, the National Laboratory for Sustainable Energy at the Technical University of Denmark -, SSP-Technology A/S and Blaest (Blade test centre A/S) and it has been performed as a part of Find Moelholt Jensen's PhD study. This report contains the complete test data for the final test, in which the box girder was loaded until failure. A comprehensive description of the test setup is given. This report deals only with tests and results. There are no conclusions on the data in this report, but references are given to publications, where the data are used and compared with FEM etc. Various kinds of measuring equipment have been used during these tests: acoustic emission, 330 strain gauges, 24 mechanical displacement devices and two optical deformation measuring systems. The mechanical displacement devices measured both global (absolute) and local (relative) deflection and the optical systems measured surface deformation. A prediction was made on the location of the failure of the girder. At this location the majority of the measuring equipment was concentrated. The prediction was proved to be correct and valuable information of the behaviour of the box girder prior to failure was obtained. The experimental investigation consisted of the following load configurations: -Flapwise bending -Torsion Ultrasonic scanning of the box girder was performed before, during and after the test the box girder. This was done to investigate whether the girder was damaged by the load or imperfection (productions defects) growth. (au)
Zheheng Chen
2015-01-01
Full Text Available Structural health monitoring (SHM has attracted much attention in recent years, which enables early warnings of structural failure, condition assessments, and rational maintenance/repair strategies. In the context of bridges, many long-span steel bridges in China have been installed with the SHM systems; however, the applications of the SHM in prestressed concrete (PSC bridges are still rather limited. On the other hand, the PSC box girder bridges are extensively used in highway and railway systems and premature damage of these bridges is often reported, resulting in considerable maintenance and/or replacement costs. First, this paper presents a state-of-art review on the SHM of long-span PSC bridges. Monitoring strategies, methods, and previous applications for these bridges are summarized and discussed. In order to well capture the behavior of the bridge during its whole life and to maximize the use of sensors, a life-cycle monitoring strategy is proposed, in which the sensor layout is determined according to requirements for construction monitoring, completion test, and in-service monitoring. A case study is made on a three-span PSC box girder bridge in China. The system configuration, sensor layout, and data communications, and so forth, are presented. The up-to-date monitored structural responses are analyzed and compared with the design values.
Iman MOHSENI; A.R.Khalim RASHID
2012-01-01
Concrete precast multicell box-girder (MCB) bridges combine aesthetics with torsional stiffness perfectly.Previous analytical studies indicate that currently available specifications are unable to consider the effect of the twisting moment (torsional moment) on bridge actions.In straight bridges the effect of torsion is negligible and the transverse reinforced design is governed by other requirements.However,in the case of skewed bridges the effect of the twisting moment should be considered.Therefore,an in-depth study was performed on 90 concrete MCB bridges with skew angles ranging from 0° to 60°.For each girder the bridge actions were determined under the American Association of State Highway and Transportation Officials (AASHTO) live load conditions.The analytical results show that torsional stiffness and live load positions greatly affected the bridges' responses.In addition,based on a statistical analysis of the obtained results,several skew correction factors are proposed to improve the precision of the simplified Henry's method,which is widely used by bridge engineers to predict bridge actions.The relationship between the bending moment and secondary moments was also investigated and it was concluded that all secondary actions increase with an increase in skewness.
The application of hybrid carbon fiber reinforced polymer (HCFRP) sensors was addressed to monitor the structural health of an existing prestressed concrete (PC) box girder bridge in a destructive test. The novel HCFRP sensors were fabricated with three types of carbon tows in order to realize distributed and broad-based sensing, which is characterized by long-gauge length and low cost. The HCFRP sensors were bonded on the bottom and side surfaces of the existing bridge to monitor its structural health. The gauge lengths of the sensors bonded on the bottom and side surfaces were 1.5 m and 1.0 m, respectively. The HCFRP sensors were distributed on the bridge for two purposes. One was to detect damage and monitor the structural health of the bridge, such as the initiation and propagation of new cracks, strain distribution and yielding of steel reinforcements. The other purpose was to monitor the propagation of existing cracks. The good relationship between the change in electrical resistance and load indicates that the HCFRP sensors can provide actual infrastructures with a distributed damage detection and structural health monitoring system. Corrections were made to this article on 13 May 2008. The corrected electronic version is identical to the print version
CFRP-Strengthening and Long-Term Performance of Fatigue Critical Welds of a Steel Box Girder
Roland E. Koller
2014-02-01
Full Text Available Empa’s research efforts in the 1990s provided evidence that a considerable increase of the fatigue strength of welded aluminum beams can be achieved by externally bonding pultruded carbon fiber reinforced polymer (CFRP laminates using rubber-toughened epoxies over the fatigue-weak welding zone on their tensile flange. The reinforcing effect obtained is determined by the stiffness of the unidirectional CFRP laminate which has twice the elastic modulus of aluminum. One can therefore easily follow that an unstressed CFRP laminate reinforcement of welded beams made of steel will not lead to a substantial increase in fatigue strength of the steel structure. This consideration led to the idea of prestressing an external reinforcement of the welded zone. The present investigation describes experimental studies to identify the adhesive system suitable for achieving high creep and fatigue strength of the prestressed CFRP patch. Experimental results (Wöhler-fields of shear-lap-specimens and welded steel beams reinforced with prestressed CFRP laminates are presented. The paper concludes by presenting a field application, the reinforcement of a steel pendulum by adhesively bonded prestressed CFRP laminates to the tensile flanges of the welded box girder. Inspections carried out periodically on this structure revealed neither prestress losses nor crack initiation after nine years of service.
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
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
钟国东
2009-01-01
该文通过对异型箱梁桥有限元模型的建立、输出数据的整理及分析,说明异型箱梁桥的空间分析方法,为类似桥梁的结构分析及设计提供了参考.%Through the establishment of finite element model for the irregular box girder bridge, and the sorting and analysis of the output data, the article explains the space analysis method of the irregular box girder bridge to provide the reference for the structural analysis and design of the similar bridges.
Difference Solution for Shear Lag Effect of Twin-cell Box Girder%单箱双室箱梁剪力滞效应的差分解
刘勇; 张丽; 张元海; 张效军
2012-01-01
从满足剪力滞翘曲应力的轴向平衡条件出发,选取三次抛物线翘曲位移模式,考虑了悬臂板宽度及上下翼板至形心轴不同距离的影响,从而更合理反映箱形梁剪力滞翘曲应力.导出了剪力滞翘曲惯性矩、惯性积和面积等几何特性计算公式.根据最小势能原理,建立了薄壁箱梁挠曲剪力滞的控制微分方程.采用有限差分法推导出变截面悬臂葙梁剪力滞效应计算式和边界条件.运用Ansys有限元软件中的Shell63单元进行建模,分析单箱双室三跨连续箱梁剪力滞效应的分布规律.对比分析了翘曲位移模式及轴力平衡条件对剪力滞效应的影响.结果表明:二、三次抛物线均不是最合理的位移模式;连续箱梁的剪力滞效应受翘曲位移模式的影响很小;轴力平衡条件对应力分布的影响亦很小.%The warping displacement pattern of cubic parabolic curve is chosen on the axial force equilibrium condition. In order to reflect the stress distribution in the box girder more rationally,the width of the cantilever plate and the distance form the top and bottom flange plates to the centre axis are fully considered. Formulas of the moment of inertia, product of inertia and sectional area for shear lag warping geometrical properties are deduced. The equations of equilibrium with considering the shear lag for thin-walled box girders are established on the basis of the variation principle. The calculation formulas and bounding conditions of shear lag effect of the continuous box girder are deduced by adopting the finite difference solution. The Shell63 unit of Ansys program is used to analyze the distributions of shear lag effect for three-span continuous box girder. The influence of distributions by longitudinal warping displacement patterns and axial force equilibrium condition is analyzed. The results show that neither of the warping displacement patterns of quadratic nor cubic parabolic curve is the most
黄中华
2012-01-01
介绍了辽宁滨海公路辽河特大桥斜拉桥钢箱梁非对称悬臂安装技术,通过对本桥方案箱梁非对称悬臂安装方案—边跨钢梁高支架上直接滑移就位连接、主跨钢梁逐段悬臂安装的方案可行性研究与实施,为同类型桥梁施工提供了很好的借鉴作用。%Asymmetric cantilever - type mounting technology of steel box girder of cable - stayed bridge of Li- aohe Bridge across Liaoning Coastal Highway is introduced; through the feasibility study and implementation of asymmetric cantilever - type mounting scheme of steel box girder of the bridge - scheme of direct slip in place con- nection on high bracket of side - span steel girder and section by section cantilever - type mounting of main span steel girder, a good reference is provided for the bridge construction of the same type.
殷玉枫; 曾光; 吕西波; 张孟辉
2012-01-01
The box girder of overhead travelling crane features typical thin-wall structure, in which fatigue crack can appear easily due to load situation and weld defects of the crane, etc. Considering such case, the Ansys finite element software is adopted for load analysis of typical working conditions of the box girder in order to figure out the position and causes of any crack, and the fracture mechanics and Ansys software are adopted for analysis and simulation of the stress field, displacement field of the fatigue crack in box girder, as well as the size of stress field, which is significant to estimate the fatigue crack expansion and remaining life of the crane box girder.%桥式起重机箱形梁是典型的薄壁结构,由于起重机受载情况及本身结构焊接缺陷等因素,在箱形梁上很容易出现疲劳裂纹.针对桥式起重机箱形梁疲劳裂纹现象,借助Ansys有限元软件,对箱形梁典型工况进行受载分析,判断出裂纹的位置及其产生原因;运用断裂力学和Ansys软件分析模拟出箱形梁疲劳裂纹的应力场、位移场以及应力场区域的大小,对起重机箱形梁进行疲劳裂纹扩展以及剩余寿命的预估都有意义.
Jensen, Find M.; Branner, K.; Nielsen, Per H. (and others)
2008-05-15
This report presents the setup and result from three static full-scale tests of the reinforced glass fiber/epoxy box girder used in a 34m wind turbine blade. One test was without reinforcement one with cap reinforcement and the final test was with rib reinforcement. The cap reinforcement test was part of a proof of concept investigation for a patent. The tests were performed at the Blaest test facility in August 2007. The tests are an important part of a research project established in cooperation between Risoe National Laboratory for sustainable energy--Technical university of Denmark, SSP-Technology A/S and Blaest (Blade test centre A/S) and it has been performed as a part of Find Moelholt Jensen's PhD thesis. This report is the second data report containing the complete test data for the three full-scale tests. This report deals only with the test methods and the obtained results, no conclusions are drawn. These can be found in papers and patent referenced in the data report. Various kinds of measuring equipment have been used during these tests: acoustic emission, force transducers, strain gauges and optical deformation measuring system (DIC). The experimental investigation consisted of the following tests: 1) Flapwise bending with no reinforcement 2) Flapwise bending with wire reinforcements 3) Flapwise bending with rib reinforcements. (au)
Application of TMD in Large Span Steel Box Girder Footbridge%TMD在大跨径钢箱梁人行桥上的应用分析
苑翔
2013-01-01
This paper introduces the Tuned Mass Damper (TMD) composition and operation principle of the structure, comparison of advantages and disadvantages of TMD and other control of steel box girder footbridge vibration methods, and combined with the Mianyang No.1 bridge footbridge of Sichuan Province as an example, through the use of text and graph-table combination method, describes vividly the practical application of TMD in large span footbridge.% 介绍了质量调谐阻尼器(TMD)的结构组成以及工作原理，比较了TMD与其它控制钢箱梁人行桥振动方法的优缺点，并结合四川省绵阳市一号桥人行桥为工程实例，通过采用文字与图、表相结合的方式，形象地阐述了TMD在大跨径人行桥中的实际应用。
郑开启; 卜红旗; 刘钊; 惠卓; 吕志涛
2013-01-01
To investigate the structural behavior of segmental precast prestressed concrete box girder un-der the regular service stage and the construction state,a span of 48 m full scale box girder model of this type was tested for the Fourth Nanjing Yangtze River Bridge approach. The assembling and loading plans were de-termined according to the geometric parameters as well as the actual constraints of the girder. This paper focuses on the static performance,such as stress and displacement changes of the girder during segment loading and transporting. Comparative finite element method analysis was also performed for checking. The model test results show that at the regular service stage,the residual deformation of the girder after unloading is small,which demonstrates that the girder keeps in elastic during loading. The tooth joints of segments work well with each other and have no relative slip;the global performance of the girder is good as monotonous. The vertical distribution of longitudinal strain at joint and between joints basically accords with hypothesis of plane section. Also,the stress increment of prestress tendons is linear to the mid-span moment change. Finally,during the segment trans-port stage,it shows that there is sufficient compressive stress of the lower flange of the girder to meet the security requirements of transporting girder.% 以南京长江第四大桥引桥为背景，开展了一孔48 m跨径体内-体外混合配束节段预制拼装箱梁的足尺模型试验，以研究该类箱梁在正常使用阶段和施工状态下的结构行为。根据试验箱梁的尺寸参数以及实际约束条件确定了拼装与加载方案。本文重点研究正常使用荷载和梁上运梁两种工况下梁体应力状况与位移变化等结构静力性能，并与试验梁实体有限元模型进行对比分析。研究结果表明：在正常使用阶段，加、卸载后拼装梁体残余变形较小，基本处于弹性工作状态，整体
郑开启; 卜红旗; 刘钊; 惠卓; 吕志涛
2013-01-01
To investigate the structural behavior of segmental precast prestressed concrete box girder un-der the regular service stage and the construction state,a span of 48 m full scale box girder model of this type was tested for the Fourth Nanjing Yangtze River Bridge approach. The assembling and loading plans were de-termined according to the geometric parameters as well as the actual constraints of the girder. This paper focuses on the static performance,such as stress and displacement changes of the girder during segment loading and transporting. Comparative finite element method analysis was also performed for checking. The model test results show that at the regular service stage,the residual deformation of the girder after unloading is small,which demonstrates that the girder keeps in elastic during loading. The tooth joints of segments work well with each other and have no relative slip;the global performance of the girder is good as monotonous. The vertical distribution of longitudinal strain at joint and between joints basically accords with hypothesis of plane section. Also,the stress increment of prestress tendons is linear to the mid-span moment change. Finally,during the segment trans-port stage,it shows that there is sufficient compressive stress of the lower flange of the girder to meet the security requirements of transporting girder.% 以南京长江第四大桥引桥为背景，开展了一孔48 m跨径体内-体外混合配束节段预制拼装箱梁的足尺模型试验，以研究该类箱梁在正常使用阶段和施工状态下的结构行为。根据试验箱梁的尺寸参数以及实际约束条件确定了拼装与加载方案。本文重点研究正常使用荷载和梁上运梁两种工况下梁体应力状况与位移变化等结构静力性能，并与试验梁实体有限元模型进行对比分析。研究结果表明：在正常使用阶段，加、卸载后拼装梁体残余变形较小，基本处于弹性工作状态，整体
Zhang, Xun; Li, Xiaozhen; Hao, Hong; Wang, Dangxiong; Li, Yadong
2016-04-01
A side effect of high-speed railway and urban rail transit systems is the associated vibration and noise. Since the use of concrete viaducts is predominant in railway construction due to scarce land resources, low-frequency (20-200 Hz) structure-radiated noise from concrete bridges is a principal concern. Although it is the most commonly used bridge type, the mechanism of noise emission from box-shaped bridge girders when subjected to impact forces from moving trains, which sounds like beating a drum, has not been well studied. In this study, a field measurement was first made on a simply-supported box-shaped bridge to record the acceleration of the slabs and the associated sound pressures induced by running trains. These data indicated that a significant beat-wave noise occurred in the box-shaped cavity when the train speed was around 340 km/h, which arose from the interference between two sound waves of 75.0 Hz and 78.8 Hz. The noise leakage from the bridge expansion joint was serious and resulted in obvious noise pollution near the bridge once the beat-wave noise was generated in the cavity. The dominant frequency of the interior noise at 75.0 Hz was confirmed from the spectrum of the data and the modal analysis results, and originated from the peak vibration of the top slab due to resonance and the first-order vertical acoustic mode, which led to cavity resonance, amplifying the corresponding noise. The three-dimensional acoustic modes and local vibration modes of the slab were calculated by using the finite element method. A simplified vehicle-track-bridge coupling vibration model was then developed to calculate the wheel-rail interaction force in a frequency range of 20-200 Hz. Numerical simulations using the boundary element method confirmed the cavity resonance effect and the numerical results agreed well with the data. Based on the calibrated numerical model, three noise reduction measures, i.e., adding a horizontal baffle in the interior cavity, narrowing
Stress analysis of deck pavement of continuous steel box girder%连续钢箱梁桥面铺装层结构应力分析
李国芬; 曹牧; 王宏畅; 朱华平
2013-01-01
正交异性钢桥面的构造复杂，用理论算法对铺装层进行力学计算，较难得到精确的计算结果。本文利用有限元通用软件对曲线钢箱梁桥浇筑式沥青铺装层进行受力分析，将正交异性钢桥面板、铺装层作为整体，建立有限元模型，研究铺装层受力变形特点。根据钢桥面铺装层常出现的病害，并结合超载及刹车产生的水平荷载对铺装层受力的影响，提出相应的桥面铺装层破坏的综合控制指标。%The geometric structure of steel deck plates is complex. So it is difficult to get precise results in the mechanics calculation of deck pavement with traditional methods. This paper adopts the finite element meth-od for the mechanics analysis of the composite guss asphalt surfacing layer of curved steel box girder bridges. By taking the orthotropic steel deck and the pavement as a whole,a reasonable finite element model which estab-lished can be used to study the stress and deformation features of the surfacing layer. According to the common diseases in steel deck pavements and the effect of the overload and the horizontal load in braking to the pave-ment,this paper puts forward the comprehensive control indicators for pavement failures.
廖霞霞; 胡明敏; 徐昊
2014-01-01
Evaluation of the box girder details of Shanghai Yangtze river can provide the basis for the bridge ’ s maintenance and repairment .The research result of “Fatigue stress spectrum study of the steel box girder of Shanghai Yangtze River Bridge ,based on the analysis of WIM data” was used to get all the details of the stress spectrum of steel box girder .Then according to BS 5400 the tenth part ,confirming S-N curve which can reflect the details quality of fatigue .Finally ,estimating the steel box girder’s life with the combination of the Miner fatigue cumulative damage rule .According to the result ,we can know that during the current oper-ating process ,the box girder details have small stress amplitude ,high cycles and small damage magnitude . These details will not bring about fatigue damage .During the current operation ,the structure will keep high safety performance and reliability .Determine the damage point and the size of the damage value is unique in this article .%通过对上海长江大桥细节寿命的估算为大桥的维护和修复提供依据。基于论文“基于WIM数据的上海长江大桥钢箱梁应力谱研究”的研究结果，得到钢箱梁各细节的应力谱，同时参考英国桥梁规范BS 5400第十部分，确定了能够体现细节疲劳性能的 S-N曲线，并结合M iner疲劳累积损伤准则，对大桥钢箱梁细节寿命进行评估。研究结果表明，在现行日常运营过程中，钢箱梁各细节应力幅值较小，循环次数多，损伤量级很小，故细节不会发生疲劳破坏，即结构在现行运营期间保持了很高的安全性和可靠度。
CALCULATION AND ANALYSIS ON FLEXURAL CAPACITY OF PRESTRESSED COMPOSITE BOX GIRDER%预应力组合箱梁抗弯能力计算分析
胡少伟; 胡汉林
2012-01-01
The prestressed steel and concrete composite beams having been widely used in engineering as a new transverse bearing component.The bending capacity is one of the most fundamental and important behaviors.The calculation formulas of elastic bearing capacity and deflection were derived considering the slip at the steel-concrete interface and the stress increments of prestressed tendons on the base of the elastic theory;and on the premise of plane section and complete composite action,the expressions of prestressed composite beam＇s ultimate plastic capability which consider the stress increments of prestressed tendons were deduced,based on the simplified plastic theory.These foumulas can reflect the characteristics of the prestressed composite box girder.It turns out that the calculation values are in good agreement with the experimental results,which meet the engineering accuracy.%预应力钢-混凝土组合梁作为一种新型的横向承重构件,在工程中得到了广泛的使用,准确计算其抗弯承载能力是工程上最为基本也是最重要的要求。该文以弹性分析理论为基础,推导了考虑交界面相对滑移和预应力增量的预应力组合梁弹性承载能力和挠度计算公式;以完全协同作用和平截面假定为前提,采用简化的塑性理论,推导了考虑预应力增量的极限抗弯承载能力计算公式。公式能够反映预应力组合梁的受力特点,计算结果与试验值吻合良好,满足工程精度。
马磊; 万水; 蒋正文; 李明鸿
2014-01-01
A formula for calculating the load transverse distribution coefficient of single box multi-cell girder with corrugated steel webs was deduced by the rigid connected beam method on the basis of the equivalent plane plate-girder model.Then,a test on a single box double-cell girder with cor-rugated steel webs was carried out to research its load transverse distribution.The research results show that the error between the load transverse distribution coefficient calculating with rigid connect-ed beam method and that obtained from test and finite element analysis is less than 7%.Compared with the finite element analysis result of the girder with midspan diaphragm,the load transverse dis-tribution coefficient calculated by the rigid connected beam method is relatively safe.Thus the rigid connected beam method can be used to calculate the load transverse distribution coefficient of the sin-gle box double-cell girder with corrugated steel webs where or not there is a diaphragm in the mids-pan of the girder.The distribution law of the load transverse distribution coefficient along the longi-tudinal of single box multi-cell girder with corrugated steel webs was suggested according to the ex-perimental results.The moment transverse distribution coefficients are mc ,where mc is the load trans-verse distribution coefficient at the middle span calculated by the rigid beam method.For the support reaction transverse distribution coefficients of the middle girder,0.6m0 is used at the end,where m0 is the load transverse distribution coefficient at the end calculated by the level principle method;mc is applicable from L/4 to L;and the transition from the end to L/4 is linear.The support reaction transverse distribution coefficients of the side girder are 0.9m0.%将单箱多室波形钢腹板箱梁等效为平面板梁模型，用刚接梁法推导了单箱多室波形钢腹板箱梁荷载横向分布系数的计算公式，并对1根单箱双室波形钢腹板箱梁进行了荷
An improved approach for analyzing shear lag effect of box girders%箱形梁剪力滞效应的改进分析方法研究
张元海; 白昕; 林丽霞
2012-01-01
以薄壁箱梁的弯曲理论为基础，从分析翼缘板的面内剪切变形和弯曲剪力流的分布规律入手，从理论上证明二次抛物线是箱形梁剪力滞效应分析中的合理翘曲位移函数。选取剪力滞翘曲位移函数时，对悬臂板和底板引入修正系数，并考虑翘曲正应力的平衡条件。对箱形梁横截面上新出现的广义内力给出明确定义并称之为剪滞力矩，从分析正应力在翘曲虚位移上的虚功出发，揭示所定义的剪滞力矩即为相应于剪力滞广义位移的广义内力。对简支箱梁和连续箱梁模型的应力计算表明，计算值与实测值吻合良好，从而证实该文的分析方法和建立的公式是正确的。挠度计算表明：剪力滞效应使简支箱梁和连续箱梁算例的跨中挠度分别增大12％和19％，工程实践中必须认真对待。%Based on the flexural theory for thin-walled box girders, quadratic parabola is proved to be reasonable as the warping displacement function in shear lag effect analysis of a box girder through investigating the in-plane shear deformation and the shear flow in the flanges. Modified factors for the cantilever and bottom slabs are introduced in the warping displacement function for shear lag and the equilibrium condition for warping stresses is also considered. The new generalized internal force is defined explicitly and named as shear lag moment, which is proved to be the generalized moment corresponding to the generalized displacement for shear lag, through analyzing the virtual work done by the normal stress on the virtual warping displacement. Simply supported and continuous box girder models are analyzed and the calculated results are in good agreement with the test results, which validates the proposed method and formulas. For the simply supported and continuous box girder models, shear lag effect increases the mid-span deflections by 12% and 19%, respectively, which should be treated
钢-混组合箱梁的车桥耦合振动影响分析%Analysis on Coupling Reaction of Steel-Concrete Composed Box Girder Vibration
汪家正
2011-01-01
随着对于钢-混组合箱梁结构研究的深入开展,其在车辆荷载作用下的车桥振动响应问题也备受关注。不同截面形式对其车-桥相互作用性能有着较大影响。文章基于模态综合法的原理,建立两种不同截面形式的钢-混组合箱梁的动力计算模型,并对其动力特性进行了比较分析,结果表明：双车响应大致为单车响应的两倍,说明不同车辆荷载作用下桥梁的反应是线性的,为以后此类桥梁的设计提供参考。%As the development of study on steel-concrete composed box girder,its natural vibration under vehicle loading draws more and more attentions.Different types of cross sections have different influence on the interaction between vehicle and bridge.Based on the component mode synthesis principle,the article builds two different types of steel-concrete composed box girder model and performs comparison analysis on its dynamic property.The result shows that the coupling reactions for two vehicles are bigger than that for one vehicle.This indicates that the relationship between them is linear,which provides reference for future bridge design.
任红伟; 刘保东; 李鹏飞
2012-01-01
In order to calculate the ultimate flexural capacity for externally prestressed box girder with corrugated steel webs, in view of its structural characteristics, considered the shear slip of shear key between the corrugated steel webs and the roof and floor concrete, the formulas of the ultimate flexural capacity of the externally prestressed box girder with corrugated steel webs were derived. As the slip strains increased the strain of the roof and floor and the sectional curvature, the influence of the interfacial slip on the ultimate flexural capacity were taken into account by the additional moment. Based on the analysis of the compatibility relation between externally prestressed tendons and the beam deformation, the stress increment of the external prestressing tendons was derived, the calculating steps of the ultimate flexural capacity of the externally prestressed box girder with corrugated steel webs by the plastic hinge method were derived and summarized, and the method was verified by model tests. The comparison of the experimental and theoretical results indicate that (1) the ultimate flexural capacity will be reduced when considering shear slip of the shear key; (2) the results obtained using the derived formulas are better than those from existing methods, which are close to the measured values and can give a reference to the calculation of the same type of girders.%为了计算体外预应力波纹钢腹板组合箱梁桥的极限抗弯承载力,针对其构造特点,考虑波纹钢腹板与顶底板混凝土剪力连接键剪切滑移的影响,推导了波纹钢腹板预应力箱梁极限抗弯承载力计算公式.滑移应变增大了项底板的应变和截面曲率,可以通过附加弯矩考虑界面滑移对极限抗弯承载力的影响；在分析体外预应力钢筋与梁体变形协调关系的基础上,得到了体外预应力筋的应力增量,推导并总结了应用塑性铰法计算波纹钢腹板体外预应力组合箱梁极限抗
Comparison of Temperature Loadings of Bridge Girders
J. Římal
2008-01-01
Full Text Available This paper compares the effect of temperature changes on the superstructure of bridges, above all the effect of non-uniform temperature. Loadings according to standards ESN 73 6203, ENV 1991-1-5 and DIN 1072 are compared here. The paper shows a short summary of temperature loading according to each standard and shows the comparison of bending moments arisen from these temperature loadings on superstructure made from continuous girder from a steel-concrete box girder with a composite concrete slab. With respect to a variety of design processes, the comparison is made without any coefficient of loading, combination or material.
一种计入桥面铺装非完善接触效应的箱梁结构计算方法%Application of Deck Pavement into Box Girder Structure
董建兴
2013-01-01
The local simulation analysis is carried out for the imperfect contact between the bridge deck pavement and the box girder structure.Then the shear stiffness is obtained from load-slip curves.And a 3-D model for a real bridge structure is built and analyzed in which Spring elements are adopted to simulate the interface shear stiffness.By this calculation model the structural responses under some loads are acquired to explore the effect of considering interface slip between the concrete box deck and the pavement on the structural behavior of the bridge.The results indicate that the cracking load and ultimate bearing capacity of structure are advanced by the affect of the pavement.By comparing the data,the advice of analyzing the box girder with deck overlays is proposed,which has definite social and economic benefit.%采用有限元软件对桥面铺装与箱梁结构桥面板之间的非完善接触进行局部仿真分析,提取荷载一滑移曲线获得界面之间的剪切刚度,并在整体模型中用弹簧单元模拟界面之间的剪切刚度,对猫铺大桥结构进行三维空间分析.通过这种计算模式分析结构在荷载作用下的的整体响应,探讨比较了考虑混凝土与桥面铺装界面滑移对箱梁结构受力性能的影响.研究得出了考虑铺装层参与截面受力能提高结构开裂荷载和极限承载能力、增大结构刚度的结论.计算结果对考虑铺装层作用时箱梁计算提出合理建议,具有一定的经济和社会效益.
王骑; 廖海黎; 李明水; 马存明
2013-01-01
回顾了机翼和箱梁的气动迟滞效应研究现状,介绍了大振幅下获取薄翼和流线型箱梁自激气动力的风洞试验.研究结果表明:薄翼在超过失速角的振幅条件下,升力并没有出现明显的失速现象,但气动力的高阶谐波分量显著增加；大振幅条件下,流线型箱梁的气动力高阶谐波分量也比较显著,并以第2和第3阶谐波分量为主.此外,在大振幅条件下,流线型箱梁的气动力矩迟滞曲线可出现“8字环”,即气动力在一个振动周期内既做了正功也做了负功；其中,迟滞曲线“8字环”的气动正功部分随着振幅和折算风速的增大而增加.该现象可导致桥梁也出现类似于失速机翼的极限环震荡.最后,基于不同振幅下流线型箱梁的力矩迟滞曲线,简要讨论了大跨度桥梁在颤振后状态可能出现的振动形式和气动稳定性.%The state-of-the-art of aerodynamic hysteresis of airfoil and box girder is reviewed briefly. A detailed introduction is given to the wind tunnel tests of motion-induced aerodynamic force measurements of thin airfoil and streamline box girder under large amplitude oscillation. The test results show that the lift stall didn't occur while the torsional amplitude exceeds the stall incidence angle, and the higher order harmonic components are remarkable in the aerodynamic force. The aerodynamic hysteresis curve of pitching moment for streamline box girder can take on "8-shape" loop, which means that the aerodynamic forces can provide both the positive and negative works within one vibration period. The limited cycle oscillation may also occur for bridge deck, which is usually observed in the stall airfoil. Based on the aerodynamic hysteresis curve of pitching moment under different amplitudes, the possible vibration pattern and aerodynamic instability are discussed for the post-flutter state of long span bridge.
张策; 邵旭东; 张阳
2015-01-01
With the precast segment cantilever method,a bracket joint between segments is proposed for the extra-long-span continuous box girder bridge composed of ultra-high performance concrete (UHPC ). The optimization analysis is conducted based on some parameters,such as the horizontal angle of bracket joint,the ratio of joint tooth block depth and height,and the ratio of joint tooth block height to beam height. The optimal ones are less than 45 ,great than 1/10, and 1/3 ~ 2/3 correspondingly. A double cantilever box girder with bracket joint is designed according to the optimization results. Combining with model tests and numerical analysis,the shear behavior of web ’s joint and the influence of diaphragm plates on the joint performance are studied. The results demonstrate that the shear behavior of web’s joint is strong,and the shear capacity of joint can be increased by intensive diaphragm plates in thin-walled box girder. The cracking strain in joint’s corner is up to 455με,and the corresponding stress is about 9. 23MPa. The results are much greater than those of the ordinary concrete joint,and the resistance cracking degree of safety approaches 1. 63.%针对超大跨径UHPC连续箱梁桥，提出悬臂拼装法施工的牛腿式UHPC节段间接缝，并对其倾角、深高比、齿梁高之比进行优化设计，得到接缝牛腿最优水平倾角为0°～45°，深高比≥1／10，齿梁高比为1／3～2／3。利用优化结果设计制作一个双悬臂梁接缝模型，采用模型试验与数值分析相结合的方法，研究薄壁箱梁拼装节段腹板接缝的抗剪性能及横隔板对腹板接缝性能的影响。静力试验的结果与数值模拟分析的结果都表明：薄壁箱梁腹板接缝抗剪性能强，密集横隔板能提高接缝抗剪承载力，接缝角趾开裂应变达到455με，相应计算应力达14．71MPa，远大于普通混凝土的接缝强度，抗裂安全度可达1．63。
孔德法
2012-01-01
鱼腹式变截面箱梁桥具有造型美观的特点,符合桥梁美学设计,但施工难度大；结合工程实例,通过建立空间直角坐标系,“从点到线、从线到面、从面到体”进行控制,思路清晰,工艺明确,较好的解决了变截面箱梁的施工难题.桥梁施工范围内淤泥深度为3.49～8.86 m,无明水,施工过程中,根据淤泥深度不同,分别采用“钻孔桩、贝雷梁”和“清淤换填、戗灰处理”两种方式对支架基础进行处理:经过施工检验,基础沉降量控制在允许范围内.%Fish-bellied box girder bridges with variable cross-section have attractive characteristics which comply with the idea of aesthetic design of bridge, but the construction is difficult. The author, in combination with actual project, established the space rectangular coordinate system to control the construction "from point to line, from line to surface, and from surface to body" with clear technological meanings and processes, therefore the construction puzzle of variable cross-section box girder was well solved. In addition, because the depth of silt within construction range is 3. 49 .8. 86 m without visible water, two ways of "bored piles plus bailey beam" and "dredging for filling, treating with ash" were adopted to deal with the support foundation during construction based on different depth of silt. The results of construction inspection show that the settlement of the foundation is within the allowed range.
王运金; 李北星; 唐凯; 胡峰强; 张剑峰
2012-01-01
为防止九江长江公路大桥主桥超宽箱梁混凝土的早期开裂,进行专门的抗裂混凝土配合比优化设计试验.通过水化热、绝热温升、平板法塑性收缩开裂、温度～应力试验机开裂等试验方法,研究了胶凝材料组成对混凝土早期抗裂性的影响,配制出抗裂性能良好的C55混凝土.该混凝土采用42.5级p·Ⅱ水泥掺入25％的Ⅰ级粉煤灰、缓凝型聚羧酸盐高性能减水剂配制,绝热温升55.8℃,塑性收缩抗裂等级Ⅱ级,开裂温度8.7℃,应力储备37.3％,实际应用效果良好.%To prevent the concrete for the very wide box girder of the main bridge of Jiujiang Changjiang River Highway Bridge from early stage cracking, the optimal design and experiment for the mix proportioning of cracking resistance concrete for the box girder was specially carried out. By way of the hydration heat testing, adiabatic temperature rise testing, flat slab testing of plastic shrinkage cracking and cracking testing of temperatures-stress testing machine, the influence of the cementitious material compositions on the early stage cracking resistance of the concrete was studied and the C55 concrete having good cracking resistance was accordingly prepared. The concrete is used with the Grade 42. 5 P?II cement added with 25% of the Grade I flyash and high-range water reducer of retarding-type polycarboxylate. The adiabatic temperature rise of the concrete is 55. 8 ?, the level of the plastic shrinkage cracking resistance is grade II, the cracking temperature is 8. 7 ? and the stress reserve is 37. 3%. The practical application of the concrete proves that the effect of the concrete is sound.
张健; 钟伟
2016-01-01
为了检验徐家湾连续刚构渡槽箱梁的安全性能，经过近42天5级加载充水试验，监测结果表明：徐家湾渡槽箱梁竖向位移与设计理论值一致，渡槽施工质量良好，结构安全。其成果可供类似连续刚构渡槽充水试验参考。%In order to check the safety of box girder of Xujiawan continuous rigid aqueduct,5-grade loading water filling test was conducted for nearly 45 days. The results of monitoring demonstrate the vertical displacement is identical with the design value,the construction quality is good,and the structure is safe. The results also can be reference for water filling test of similar rigid aqueduct.
邵旭东; 詹豪; 雷薇; 张哲
2013-01-01
A novel super-long-span continuous box-girder bridge made from ultra-high-performance concrete (UHPC) was proposed.By combining UHPC,thin-walled box girder with dense diaphragm plates and partial external prestressing into the novel box-girder system,a traditional three-dimensional prestressed structure is transformed into a longitudinal one-way prestressed one.Hence,not only can the main span length of girder bridges be improved,but also the ever existing problems in long-span PC bridges,such as the cracking in concrete girders and the excessive deflection at midspan,may be eliminated.A trial-design for a continuous box-girder bridge built from UHPC with main span length of 400m is presented,and the results show that the thicknesses of its components can be decreased greatly,the transverse stress decreased effectively by using the dense diaphragms,and the self-weight of superstructure may be reduced about 50％ so that a good economy may be achieved and the one-way prestressed structure is completely feasible.The model tests were carried out to evaluate the creep deformation and shear capability of UHPC beam,and the results show that the creep deformation of UHPC beam is only 20％ of that of ordinary concrete beam,and the shear capability of web can be further enhanced by employing dense diaphragms.The novel super-long-span continuous box-girder bridge is a competitive candidate in the aspects of safety,economy and durability,implying that it is applicable to the continuous girder bridge with main span length of 400m.%提出一种超大跨径超高性能混凝土(UHPC)连续箱梁桥新体系.新体系梁桥将超高性能混凝土(UHPC)、密集横隔板薄壁箱梁和部分体外预应力有机结合,变传统三向预应力为纵向单向预应力结构,不仅提升了梁桥跨径,而且可消除传统大跨径PC梁桥的主梁过度下挠和梁体开裂两类病害,通过对跨径400m的UHPC连续箱梁桥试设计,结果表明,新体系箱梁桥各种板件
吉伯海; 叶枝; 傅中秋; 汪锋; 孙洪滨
2016-01-01
为准确评估钢桥结构的疲劳损伤状态和剩余疲劳寿命，以江阴长江大桥为背景，对该桥钢箱梁疲劳裂纹产生位置进行连续疲劳应变监测，获取应变时程数据，结合雨流计数法技术建立日疲劳应力谱；分析应力幅～循环次数分布规律；研究累积损伤度分布特征，建立损伤度分布模型，计算不同车道构造细节疲劳损伤度和剩余寿命。研究结果表明：钢箱梁顶板测点、U肋与横隔板焊接末端处、弧形缺口有效截面最小处均以压应力为主，U 肋以拉应力为主；应力幅累积循环次数分布服从Weibull函数分布；疲劳累积损伤度分布服从Boltzman函数分布，顶板与U肋连接处U肋腹板沿横桥向慢车道疲劳损伤较快车道损伤大，下游车道较上游车道损伤大，其中下游慢车道U肋腹板细节疲劳损伤最大。%To accurately evaluate the fatigue damaging condition and remaining fatigue life of steel bridge structure ,the Jiangyin Changjiang River Bridge was cited as an example .Continuous fatigue strain monitoring was conducted at the locations where fatigue cracks were found on the steel box girder to gain real‐time strain data .The monitoring data ,combined with the rain flow counting method ,were used to set up the daily fatigue stress spectrum to analyze the distribution law of S~ N curve .The distribution law of fatigue accumulating damage was studied .The model of damage distribution was set up ,to calculate the fatigue damages and remaining life of different structural details of the traffic lane .T he results of the study demonstrate that compressive stress was dominant at the testing locations in the steel box girder ,ends of U‐rib and diaphragm welds and least effective cross section of the arc notches ,whereas tensile stress was found primarily on U ribs .The distribution of the accumulated stress cycle follows the way of Weibull function distribu‐tion .The distribution
Research on temperature field and temperature stress of prestressed concrete girders
Chen Cheng; Kaiyin Zhang
2011-01-01
This paper introduces the establishment and simplification of the temperature field and the general calculation method of temperature stress of the prestressed concrete box girders. Three kinds of sunshine temperature gradient models were loaded to a real bridge respectively, and got stress and displacement curves. Research data of several prestressed concrete box girders were selected from different regions of China to compare the relative error of the calculated and measured value. We indic...
邵旭东; 张良; 张松涛; 欧阳泽卉
2016-01-01
针对新型UHPC连续箱梁桥的结构特点及预应力体系布置，对其腹板处体外预应力下折索进行齿块锚固研究。对独立矩形齿块进行应力分析，揭示板厚对锚固区壁板外侧“局部弯曲效应”的影响。通过拓扑优化分析构建出一个揭示齿块锚固区传力机理的简化平面杆系模型，提出两种齿块锚固区局部加强的方法。在此基础上，对UHPC箱梁桥的腹板体外预应力锚固齿块进行构造设计，对比6种不同锚固方案，分析横隔板、预应力筋齿块内转向和锚固长度对锚固区受力的影响，最终得出较为合理的体外预应力齿块锚固构造形式。%According to the characteristics of a novel continuous UHPC box-girder bridge and the lay-out of its prestressing system,the anchor block for external tendons on the web was studied.Firstly,the effect of the plate thickness on the“local bending effect”in anchorage zone was evaluated through the anal-ysis of stress in the isolated rectangular anchor block.A simplified plane linkage model was proposed through the topology optimization in order to study the force transfer mechanism in anchorage zone.More-over,two kinds of methods were developed to strengthen the anchorage zone based on the simplified mod-el.On the basis of the above research procedure,six different anchoring schemes of the anchor block for the external tendons were designed.After analyzing and comparing the performance of the different ancho-ring schemes,the effects of diaphragms,steering of prestressing tendons,and anchoring length of the an-chor block on the mechanical behavior of the anchorage zone were evaluated.Finally,a type of reasonable anchor block of the external tendons was obtained.
张元海; 康喜东; 林丽霞
2012-01-01
Based on the flexural theory of thin-walled box girder, the curve of quadratic parabola is proved to be the reasonable form of the warping displacement function in the shear lag effect analysis of a box girder through investigating the in-plane shear deformation and the bending shear flow distribution in the flanges. The additional deflection induced by shear lag effect is adopted as the generalized displacement. The governing differential equations and the corresponding boundary conditions for shear lag effect of box girder are established by the energy calculus of variations based on the principle of minimum poten- tial energy. The new generalized internal force is defined rigorously,and a simple and convenient formula of stress for shear lag warping is presented which has the same form as the bending stress of elementary beam. A simply supported box girder model is analyzed and the calculated results are in good agreement with the test results, validating the method and formula presented. The generalized moment for shear lag differs from the bending moment in distribution and attenuates quickly. For the simply supported box girder example under concentrated load, shear lag effect increases the mid-span deflection by 12 ~,which should be treated carefully in practice.%以薄壁箱梁的弯曲计算理论为基础，从分析翼缘板的面内剪切变形和弯曲剪力流的分布规律入手，从理论上证明二次抛物线是箱形梁剪力滞效应分析中的合理翘曲位移函数。选取剪力滞效应引起的附加挠度作为广义位移，用基于最小势能原理的能量变分法建立箱形梁剪力滞效应分析的控制微分方程和边界条件。对箱粱横截面上新出现的广义内力给出严密定义，并建立了剪力滞翘曲应力的简便计算公式，它与初等梁弯曲应力公式具有相同的形式。对一个简支箱梁模型的计算表明，计算值与实测值吻合良好，从而证实了本文的分析方
吴多; 李青宁
2014-01-01
Traveling wave effect is a main influence factor for the multi-support excitation of large-span structures .It has been unable to meet the needs of engineering earthquake-resistance without considering the traveling wave effect of earth -quake ground-motion ,especially for the curve bridges by complex loading .Large mass model is currently used for the analysis of the traveling wave effect ,then the displacement differential method is used to calculate the relative displace-ment of the structure .However ,the displacement differential method often can lead to displacement “drift” and distortion for more support of large-span structures .Taking a five cross curve box girder bridge as an example ,a traveling wave processing method based on the basal coefficient reduction is proposed ,and the different apparent-wave velocity is used for seismic time-history response analysis .The results show that under the seismic action ,the traveling wave effect is fa-vorable for structural displacement ,and considering the traveling wave of reduction factor can better fix the actual dis -placement under the action of earthquake .Finally when considering the traveling wave effect ,the variable parameters such as the apparent-wave velocity and high pier have a greater influence on the seismic response of curve bridge .There-fore ,in the seismic analysis of curve bridge ,the specific requirements of engineering should be considered for contrast calculation so as to ensure the safety of the design .%行波效应是目前大跨结构中考虑多点激励的一种主要影响因素。特别是针对受力复杂的曲线桥，不考虑地震动的行波效应已经不能满足工程抗震的需求。目前常用大质量模型进行行波效应的分析，然后利用位移差动的方法求出结构的相对位移。对于多支撑的大跨结构来说位移差动的方法经常会导致位移的“漂移”和失真。以一座五跨曲线箱梁桥为例，提出了一种
Yue Zheng; Xiang Xiao; Lunhai Zhi; Guobo Wang
2015-01-01
This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abut...
马玉臣
2011-01-01
The use of large post-tensioning pre-stressed high-performance concrete box girders used in deepwater berths especially for ore terminals to accommodate ships of more than 250 000 tons is still unprecedented in China. The paper describes that the prestressed girders are suitable for the load and process requirements through various quality control procedures during the construction of Caofeidian Ore Terminal and the successful engineering practice ran provide references for similar projects.%大型后张预应力高性能混凝土箱梁应用在深水泊位特别是25万吨级以上的矿石码头国内尚无先例,文中阐述了该预应力梁在曹妃甸矿石码头工程施工过程中通过多方面质量控制,较好地适应了荷载和工艺要求,其成功应用可为以后类似工程提供借鉴.
杨婷; 周志勇
2015-01-01
To study vortex-induced resonance characteristics and anti-vibration measures'mechanism of central-slotted box girders,the large-scale sectional model vibration measurement,pressure measurement and CFD were employed.A long-span cable-stayed bridge over Yangtze River was taken as an example to conduct wind tunnel tests of large-scale sectional model.The test results indicated that it is the maintenance rails located inside aerodynamic susceptible sites that cause the vortex-induced vibration of the bridge.CFD numerical simulation results showed that the upwind flow passing through the curved soffit plate is hindered by the inside maintenance rails to cause an increased width of dead water region in the wake of upwind box section,a continuous and intensive vortex shedding phenomenon occurs due to velocity gradient and the VIV of the bridge main beam section takes place;accordingly,the inside maintenance rails are proposed to offset the center line of the main beam with a certain distance,they are not an obstacle to the high-speed upwind flow;thus the flow separates at the location far away from the knuckle line and the size of dead water region in the upwind box wake is reduced to prevent the vortex shedding.The static pressure test results showed that when shifting the inside maintenance rails,the negative mean pressure at the soffit plate knuckle line,does not change dramatically,the fluctuating pressures on the upwind and downwind inclined panels can be reduced,and the fluctuating energy is dispersed without a consistent predominant frequency.Wind tunnel tests for the modified section were conducted and the results showed that the VIV of the bridge can be suppressed completely.%基于大比例节段模型风洞测振、测压试验及计算流体力学（Computational Fluid Dynamic，CFD）方法进行中央开槽箱梁涡激共振特性及抑振措施机理研究。以芜湖长江公路二桥为例进行大比例节段模型风洞试验。结果显示，位于
吴焕庆; 张俊波; 刘世忠; 冀伟; 满自亭
2013-01-01
Under the condition of the plane section assumption and without considering the inertia moment of corrugated steel webs,this paper establishes the additional axial force formula for the two spans continuous box-girder bridge with corrugated steel webs based on a cubic parabola shear lag warping function.At the same time,it leads into the additional axial force stress ratio coefficient.Then it analyses the impact of additional axial stress to the influence degree of structural mechanical,which is based on the continuous box-girder bridge with corrugated steel webs under the full cross-uniformly distributed load and mid-span concentrated load.It shows that the value of additional axial stress can be ignored because the additional axial force stress ratio coefficient under the full cross-uniformly distributed load and the mid-span concentrated load is less than 1％.%基于平截面假定并不计波形钢腹板惯性矩,建立了波形钢腹板两跨连续箱梁在三次抛物线剪滞翘曲位移函数下的附加轴力计算式.引入附加轴向应力比系数,分析了波形钢腹板混凝土两跨连续梁在均布荷戢及跨中集中荷载作用下,附加轴向应力对结构受力性能的影响,分析表明:在两种荷栽工况下,附加轴向应力比系数均小于1％,可以忽略其效应.
Distortional Buckling Analysis of Steel-Concrete Composite Girders in Negative Moment Area
Zhou Wangbao
2014-01-01
Full Text Available Distortional buckling is one of the most important buckling modes of the steel-concrete composite girder under negative moment. In this study, the equivalent lateral and torsional restraints of the bottom flange of a steel-concrete composite girder under negative moments due to variable axial forces are thoroughly investigated. The results show that there is a coupling effect between the applied forces and the lateral and torsional restraint of the bottom flange. Based on the calculation formula of lateral and torsional restraints, the critical buckling stress of I-steel-concrete composite girders and steel-concrete composite box girders under variable axial force is obtained. The critical bending moment of the steel-concrete composite girders can be further calculated. Compared to the traditional calculation methods of elastic foundation beam, the paper introduces an improved method, which considers coupling effect of the external loads and the foundation spring constraints of the bottom flange. Fifteen examples of the steel-concrete composite girders in different conditions are calculated. The calculation results show a good match between the hand calculation and the ANSYS finite element method, which validated that the analytic calculation method proposed in this paper is practical.
Yue Zheng
2015-01-01
Full Text Available This paper aims to evaluate the impact interaction between the abutment and the girder subjected to nonuniform seismic excitation. An impact model based on tests is presented by taking material properties of the backfill of the abutment into consideration. The conditional simulation is performed to investigate the spatial variation of earthquake ground motions. A two-span continuous steel box girder bridge is taken as the example to analyze and assess the pounding interaction between the abutment and the girder. The detailed nonlinear finite element (FE model is established and the steel girder and the reinforced concrete piers are modeled by nonlinear fiber elements. The pounding element of the abutment is simulated by using a trilinear compression gap element. The elastic-perfectly plastic element is used to model the nonlinear rubber bearings. The comparisons of the pounding forces, the shear forces of the nonlinear bearings, the moments of reinforced concrete piers, and the axial pounding stresses of the steel girder are studied. The made observations indicate that the nonuniform excitation for multisupport bridge is imperative in the analysis and evaluation of the pounding effects of the bridges.
高立强; 蒲黔辉; 施洲
2011-01-01
The scheme of steel box girder used in the design of Yongjiang Railway Cable-stayed Bridge of Ningbo city is the first case in railway bridges in China. For railway bridges, the transverse position of steel rails is stable, and bridge deck pavement is different from that of highway bridges. In order to study the difference of orthotropic deck used in railway bridge and highway bridge, railway bridge and highway bridge deck pavements were installed on the deck separately. With the finite element method, the transverse and longitudinal influence lines of the stresses in the fatigue-sensitive regions with different bridge deck pavements were calculated. The reason why the stress in each fatigue-sensitive region was studied, and the characteristics of steel box girder orthotropic deck for railway bridge and highway bridge were analyzed. With the representative railway and highway vehicles as the loads, the stresses of steel box girder orthotropic deck in some fatigue-sensitive regions were calculated. The results of analysis and calculation show that (1 ) The dispersion of asphalt concrete deck pavement for highway bridge is weak, while that of railway bridge deck pavement is strong. Compared with highway bridge, the values of influence lines of the stresses in the fatigue-sensitive regions are smaller, and the lengths of influence lines are longer for railway bridge. (2) Under theload of normal railway vehicle, the largest stresses of rib-to-diaphragm joint and edge of cutout in diaphragm are similar to that under the load of normal highway vehicle. (3) In comparison with railway bridge, fatigue cracks are likely to emerge at the rib-to-deck joint for highway bridge orthotropic deck.%宁波甬江铁路斜拉桥在设计中采用钢箱梁方案,在铁路桥中为国内首例.铁路桥梁钢轨横向位置固定,桥面铺装也与公路桥梁不同,为研究钢箱粱正交异性板用于铁路桥梁和公路桥梁的区别,在桥面板上分别设置铁路与公路铺
Committee VI.1. Extreme Hull Girder Loading
Jensen, Jørgen Juncher
2000-01-01
Committee Mandate. Evaluate and develop direct calculation procedures for extreme wawe loads on ship hull girders. Due consideration shall be given to stochastic and non-linear effects. The procedures shall be assessed by comparison with in-service experiences, model tests and more refined...
Critical Strength of steel Girder Web
Pratibha M Alandkar; Sandeep M Shiyekar; Mukund R Shiyekar
2016-01-01
When a member is subjected to combined action of bending moment, shear and axial force, bending moment & axial force is assumed to resist by whole section and shear is resisted by web only. In such case web shall be designed for combined shear and axial force. The present study determines the strength of web of steel girder under the action of pure shear, pure axial force and combination of it. The classical plate buckling theory is already established to determine the critical buckling st...
Behaviour of parallel girders stabilised with U-frames
Virdi, Kuldeep; Azzi, Walid
2010-01-01
Lateral torsional buckling is a key factor in the design of steel girders. Stability can be enhanced by cross-bracing, reducing the effective length and thus increasing the ultimate capacity. U-frames are an option often used to brace the girders when designing through type of bridges and where...... overhead bracing is not practical. This paper investigates the effect of the U-frame spacing on the stability of the parallel girders. Eigenvalue buckling analysis was undertaken with four different spacings of the U-frames. Results were extracted from finite element analysis, interpreted and conclusions...
Shear design recommendations for stainless steel plate girders
Saliba, Najib; Real, E.; Gardner, Leroy
2014-01-01
The behaviour and design of stainless steel plate girders loaded in shear is investigated in this paper. A review of existing methods for the design of stainless steel plate girders, including codified provisions, is first presented. A database of thirty-four experiments carried out on austenitic, duplex and lean duplex stainless steel plate girders is then reported, and used to assess the current shear resistance design equations from Eurocode 3: Part 1.4 and Eurocode 3: Part 1.5 and the rec...
BENDING-SHEAR INTERACTION OF LONGITUDINALLY STIFFENED GIRDERS
Beg, Darko; Sinur, Franc
2011-01-01
To understand behaviour of longitudinally stiffened plated girders subjected to high bending moments and shear forces, four tests on large scale test specimens were performed. The results of these tests were used to verify the numerical model, which was employed for further parametric studies. With a verified simplified numerical model a parametric nonlinear analysis was systematically carried out to determine the resistance of longitudinally stiffened plated girders. Based on 630 numerical s...
Life-Cycle Management Strategy on Steel Girders in Bridges
So, Kevin K. L.; Moe M. S. Cheung; Zhang, Eric X. Q.
2012-01-01
The major problems affecting the service life of bridges are related to various factors such as fatigue-sensitive details, increased service loads, corrosion deterioration, and the lack of proper maintenance. Among them, corrosion deterioration and fatigue damages of structures particularly to steel girder bridges are the most common ones. Bridges of different structural forms, at different locations or under different climates, may suffer from various degrees of deterioration. Steel girders ...
Experimentally Validated Nonlinear Analysis of Bridge Plate Girders with Deformations
Kużawa Mieszko
2015-09-01
Full Text Available Comprehensive methodology of numerical nonlinear analysis of the consecutive phases in the structural behaviour of bridge plate girders with deformations is presented. The analysis concerns all stages of structure loading until failure and especially determination of the ultimate shear load capacity. Verification and validation of the numerical procedures proposed is based on comparison of the calculated results with effects of experimental laboratory shear capacity tests of plate girders carried out at the University of Ljubljana.
罗扣; 王东晖; 张强
2013-01-01
The main part of the Hong Kong-Zhuhai-Macau Bridge is a part of the combined bridge and tunnel,of which the non-navigable span bridge in the shallow water area is the 85 m span continuous composite girder bridge that totally has 64 spans of the composite girders and is 5 440 m in length.The span arrangement of the bridge mainly includes two kinds of arrangement of 6)× 85 m and 5)× 85 m.The composite girders are the separated continuous single-cell singlebox girders with constant depth and specifically are composed of the open steel box girders and the concrete deck slabs that are connected each other via shear studs.A steel box girder is the inverted trapezoid structure,a concrete deck slab is the precast full slab in the transverse direction and the grooves are pre-reserved at the locations of the shear studs.To improve the transverse mechanical behavior of the deck slabs,the stringers are set in the sections of the composite girders and to keep the integrity of the slabs,the shear studs are arranged in a way of clustering.The composite girders are erected and installed in each full span by the large transportation and erection floating crane and the girders are closed span by span.%港珠澳大桥主体工程采用桥隧组合方案,其中浅水区非通航孔桥采用85 m连续组合梁桥形式,全长5 440m,共64孔,跨径布置主要采用6×85 m和5×85m2种形式.组合梁采用单箱单室分幅等高连续梁,由开口钢箱梁和混凝土桥面板通过剪力钉联结而成.钢箱梁为倒梯形结构;混凝土桥面板为横向整块预制,在剪力钉处设置预留槽.为改善混凝土桥面板的横向受力性能,该桥组合梁截面设置小纵梁;为保持桥面板的整体性,剪力钉采用集束式布置方式.组合梁采用大型运架一体浮吊整孔安装架设,逐孔合龙.
Stress analysis of the welds in the girder
The girder at the back of each module plays an important structural role in the assembly of the Tilecalorimeter barrel. It is important, therefore, to clearly understand the welds within the girder. In order to understand the stresses in the welds, a 2-dimensional finite element model has been constructed of the girder cross section similar to the model that has been previously used by J. Blocki to analyze the girder. The current European welding norms do not require stress concentrations within welds to be considered except under fatigue loading conditions. Since this is not the case for this design, the use of the average stress in sizing the welds is allowed under the European welding norms. An analysis of the welds by V. Romanov that only considered the average stress, showed that the average weld stress was 38N/mm2, well within acceptable limits. However, it should be kept in mind that the forces on the welds vary significantly along the length of the girder so the average stress may not be an adequate method of analyzing these welds. In addition, since these welds are so critical to the structural integrity of the Tilecalorimeter, it is desirable to examine stress concentrations even though this is not required by the european norms. Therefore, it is recommended that a 30mm wide bar as shown in Figure 3 be used on the ten modules that see the highest load from the cryostat. This is a very simple and low-cost modification to a small number of girders that will provide significant additional safety
Experiments and theory on deck and girder crushing
Simonsen, Bo Cerup; Ocakli, Hasan
1999-01-01
This paper is concerned with theoretical and experimental analysis of deep plastic collapse of a deck or deep girder subjected to an in-plane, concentrated load. A theory is derived which is valid until initition of fracture in the structure. The presented experimental results show load-deflectio...
Suspension Bridge Flutter for Girder with Separate Control Flaps
Huynh, T.; Thoft-Christensen, Palle
Active vibration control of long span suspension bridge flutter using separated control flaps (SFSC) has shown to increase effectively the critical wind speed of bridges. In this paper, an SFSC calculation based on modal equations of the vertical and torsional motions of the bridge girder includi...
Preliminary study to facilitate smart structure systems in bridge girders
Kirkpatrick, Thomas C.; Peterson, Danford O.; Rossi, Peter J.; Ray, Laura R.; Livingston, Richard A.
1999-05-01
Sensors are currently available and used to monitor structural performance and loads incurred by bridges already in service. However, there has been limited research concerning the stresses that steel bridge girders endure during transport from the manufacturer to the job site and during the installation process. This paper reports the measured stresses on steel bridge girders during transportation from Lancaster, PA to Hanover, NH and during construction of the Ledyard Bridge on the New Hampshire - Vermont border. Two different monitoring system were developed for this data acquisition in a mobile environment. The first, a fiber optic strain monitoring system, utilizing Bragg grating technology. The second utilized an electrical- resistive foil strain gage network, in conjunction with wireless telemetry equipment. Together, these two systems formed a smart structure system for monitoring bridge girders while confirming the accuracy of data gathered through redundancy. Result conclusively demonstrated for the first time, that stresses in beams during transportation are significant and approach the factor of safety margin in girder design.
Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete
Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Manlone, Brian J.
2000-01-01
Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ha...
Analysis of Load Test on Composite I-Girder Bridge
Huseynov, F.; Brownjohn, J. M. W.; O'Brien, Eugene J.; Hester, David
2016-01-01
This paper showcases the importance of field testing in efforts to deal with the deteriorating infrastructure. It demonstrates a load test performed on a healthy but aging composite reinforced concrete bridges in Exeter, UK. The bridge girders were instrumented with strain transducers and static strains were recorded while a four-axle, 32 tonne lorry remained stationary in a single lane. The results obtained from the field test were used to calculate transverse load distribution factors (DFs)...
Life-Cycle Management Strategy on Steel Girders in Bridges
Kevin K. L. So
2012-01-01
Full Text Available The major problems affecting the service life of bridges are related to various factors such as fatigue-sensitive details, increased service loads, corrosion deterioration, and the lack of proper maintenance. Among them, corrosion deterioration and fatigue damages of structures particularly to steel girder bridges are the most common ones. Bridges of different structural forms, at different locations or under different climates, may suffer from various degrees of deterioration. Steel girders at different positions of a bridge may also suffer from different degrees of damage. How to effectively maintain the bridge asset at a minimal cost and how to predict the time for future works are crucial, particularly when government funding sources become stretched. A comprehensive bridge management framework assisting stakeholders to appropriately and reasonably prioritize their future maintenance-related works in their bridge stocks, such that stakeholders can better allocate the limited resources, is utmost concerned. This paper proposes an integrated life-cycle management (LCM strategy on steel girders in bridges in which corrosion deterioration and fatigue damage prediction models are mapped with girders’ performance conditions. A practical example to demonstrate the applicability of the proposed LCM strategy is also illustrated.
Precast Prestressed Concrete Truss-Girder for Roof Applications
Peter Samir
2014-01-01
Full Text Available Steel trusses are the most popular system for supporting long-span roofs in commercial buildings, such as warehouses and aircraft hangars. There are several advantages of steel trusses, such as lightweight, ease of handling and erection, and geometric flexibility. However, they have some drawbacks, such as high material and maintenance cost, and low fire resistance. In this paper, a precast concrete truss is proposed as an alternative to steel trusses for spans up to 48 m (160 ft without intermediate supports. The proposed design is easy to produce and has lower construction and maintenance costs than steel trusses. The truss consists of two segments that are formed using standard bridge girder forms with block-outs in the web which result in having diagonals and vertical members and reduces girder weight. The two segments are then connected using a wet joint and post-tensioned longitudinally to form a crowned truss. The proposed design optimizes the truss-girder member locations, cross-sections, and material use. A 9 m (30 ft long truss specimen is constructed using self-consolidated concrete to investigate the constructability and structural capacity of the proposed design. A finite element analysis of the specimen is conducted to investigate stresses at truss diagonals, verticals, and connections. Testing results indicate the production and structural efficiency of the developed system.
S M Mosavi; A Sadeghi Nik
2015-02-01
Applying composites in order to strengthen and renew the infrastructures has globally been accepted. Traditional methods to strengthen the out-of-standard structures are costly, time consuming and requires a lot of labour. Today, new techniques are hired using light and strong substances which also resist against corrosion, known as Carbon Fibre Reinforced Polymer (CFRP) plates. Regarding the high tensile strength and proper module of elasticity, CFRP plates are considered as a suitable alternative to strengthen girders. The behaviour of steel–concrete composite girders being statically loaded and strengthened by CFRP plates in this study. The CFRP plates used in this study have been stuck, with epoxy adhesive, under the tensile sections of three steel girders. The results accompanied with analytical study of moment–curvature and numerical analysis done with ANSYS, show that CFRP plates with epoxy adhesive increases the ultimate loading capacity of steel–concrete composite girder. Plastic stiffness of the girders was also increased.
Effects of vertical girder realignment in the Argonne APS storage ring
The effects of vertical girder misalignments on the vertical orbit of the Advanced Photon Source (APS) storage ring are studied. Partial sector-realignment is prioritized in terms of the closed-orbit distortions due to misalignments of the corresponding girders in the sectors. A virtual girder-displacement (VGD) method is developed that allows the effects of a girder realignment to be tested prior to physically moving the girder. The method can also be used to anticipate the corrector strengths needed to restore the beam orbit after a realignment. Simulation results are compared to experimental results and found to reproduce the latter quite closely. Predicted corrector strengths are also found to be close to the actual local corrector strengths after a proof-of-principle two-sector realignment was performed
Composite Steel-Concrete Girders with Circular Holes
Feneşan, Crina; Moga, Cătălin
2015-01-01
In this paper some aspects concerning the design of steel-concrete composite structures are presented. The steel girders are built-up as rolled sections with circular holes in webs. This paper also presents, an adaptation of Euro norms EN 1994-1-1:2004. Eurocode 4 - Design of composite and concrete structures – Part 1-1: General rules for buildings and EN 1994-2:2004. Eurocode 4 - Design of composite and concrete structures – Part 2: General rules and rules for bridges to the design of comp...
On the Influence of Hull Girder Flexibility on the Wave
Seng, Sopheak; Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher
2012-01-01
(CFD) solving the Navier-Stokes equations with the free surface captured by a volume-of-fluid (VOF) method. In all procedures the flexibility of the hull girder is modelled as a non-uniform Timoshenko beam. It is observed that the non-linear models agree well with the model tests and as there is no...... occurrence of severe slamming in the cases considered, the inexpensive non-linear strip theory is as accurate as the direct CFD calculation method. In a comparison with the results using the rigid body assumption, the increase in the vertical bending moment (VBM) amidships due to the flexibility of the hull...
Hordijk, D.A.; Bruggeling, A.S.G.; Kaptijn, N.
1998-01-01
In the Netherlands a pilot project has started to recognize the possibilities of non-metallic materials for prestressing. This project will also serve to gather more knowledge regarding the properties of non-metallic wires, their anchorages and their application in large tendons. It is intended to a
Design of bridge crane girder strain acquisition system based on virtual instrument
Wenxue LIU
Full Text Available Girder is an important part of the bridge crane, which is also the main force element. In order to prevent accidents, it is necessary to collect the bridge crane girder stress data to analyse the fatigue life. This paper constructs a bridge crane girder strain acquisition system. The hardware system consists of sensors, connectors, data acquisition cards, wireless data transmission groups, POE power and host computer. The software system consists of NI MAX to interface with the computer's NI hardware and software resources,and LabVIEW programming to display and storage the girder strain data. Through this system, positions and working days strain data acquisition for the 50/10 t bridge crane girder gets the key positions strain data. The results show that the girder strain data acquisition system runs stably, channel signals of acquisition task transmit accurately, and the terminal data stores competely, meeting the detection requirements, which provides an important data support for the subsequent fatigue analysis and accurate remaining service life prediction of the crane girder.
Redistribution of internal forces in composite concrete girders made continuous vs. time
Mašović Snežana
2011-01-01
Full Text Available Research on the long-term behavior of composite concrete girders made continuous is presented in the paper. Concrete precast element is cracked under construction load. Creep and differential shrinkage of precast and in-situ cast part of the girder also induce stresses in a structure. The subject of this investigation is redistribution of section forces in course of time for concrete girders subjected to change of the structural system. The aim of investigation is to verify design models and analytical procedures by experimental research.
Norsen, T
2005-01-01
At the 1927 Solvay conference, Einstein presented a thought experiment intended to demonstrate the incompleteness of the quantum mechanical description of reality. In the following years, the thought experiment was picked up and modified by Einstein, de Broglie, and several other commentators into a simple scenario involving the splitting in half of the wave function of a single particle in a box. In this paper we collect together several formulations of this thought experiment from the existing literature; analyze and assess it from the point of view of the Einstein-Bohr debates, the EPR dilemma, and Bell's theorem; and generally lobby for Einstein's Boxes taking its rightful place alongside similar but historically better-known quantum mechanical thought experiments such as EPR and Schroedinger's Cat.
Norsen, Travis
2004-01-01
At the 1927 Solvay conference, Einstein presented a thought experiment intended to demonstrate the incompleteness of the quantum mechanical description of reality. In the following years, the thought experiment was picked up and modified by Einstein, de Broglie, and several other commentators into a simple scenario involving the splitting in half of the wave function of a single particle in a box. In this paper we collect together several formulations of this thought experiment from the exist...
Onboard monitoring of fatigue damage rates in the hull girder
Nielsen, Ulrik Dam; Jensen, Jørgen Juncher; Pedersen, Preben Terndrup;
2011-01-01
taking into account whipping stresses. It is conceptually shown how such a method, which integrates onboard estimation of sea states, can be used to deduce decision support with respect to the accumulated fatigue damage in the hull girder.The paper firstly presents a set of measured full-scale wave......-scale onboard acceleration and stress measurements can be used to calculate sea state parameters. These calculated environmental data are verified by a comparison to hindcast data.In the third part of the paper the full-scale fatigue stress ranges are compared to results from an analytical design oriented...... calculation procedure for flexible ship hulls in short-term estimated sea states.Altogether, it is conceptually shown that by a combination of the onboard estimated sea state parameters with the described analytical fatigue damage prediction procedure a method can be established for real-time onboard decision...
Development of high performance precast/prestressed bridge girders
Akhnoukh, Amin K.
Demand continues to increase for bridges with long spans and shallow depths. Due to safety concerns, four-span overpasses are being replaced with two span overpasses to avoid placement of piers near the highway shoulders. In the meantime, the bridge profile is restricted due to existing businesses nearby. Thus, nearly the same superstructure depth must be used for double the span length. This dissertation focuses on topics aiming at providing precast prestressed concrete girders with the shallowest possible depth for a given span. It forms parts of larger projects conducted by the University of Nebraska for the Nebraska Department of Roads and for the Wire Reinforcement Institute. Specifically, the following issues were researched: (1) Use of 0.7 in. diameter Grade 270 ksi strands for pretensioning of precast concrete girders at a strand spacing of 2 inches by 2 inches. This arrangement gives nearly 190 percent of the prestressing with 0.5 in. diameter strands and nearly 135 percent with 0.6 in. strands. The research focuses on the required confinement steel to allow determination of transfer and development lengths according to current procedures in the AASHTO LRFD Bridge Design Specifications for smaller strands. (2) Develop a self consolidating concrete (SCC) mix, using Nebraska aggregates that will allow for a specified design strength at service of 15 ksi and a minimum strength at one day of 10 ksi, representing the demand at the time of release of the prestress to the concrete member. Prior to this study, standard concrete strength prevailing in Nebraska has been 8 ksi at service and 6.5 ksi at release. It was the goal of the research to keep the cost of materials as low as possible but not exceeding 250 per cubic yard, compared to the proprietary mixes that cost approximately four times this amount. (3) Use of 80 ksi welded wire reinforcement (WWR) as the auxiliary reinforcement for shear, web end splitting and flange confinement. This would result in higher
The Viability of Steel-Concrete Composite Girder Bridges With continuous Profiled Steel Deck
Hatlee, Jonathan Russell
2009-01-01
The continuous permanent metal deck form system provides a quick and efficient method of constructing short-span, simply supported composite steel girder bridges. However, because shear studs can only be welded to the girder through the steel deck at rib locations, the number of shear stud locations is limited to the number of ribs in the shear span while the spacing of the shear studs is restricted to the rib spacing of the steel deck. This results in a condition where various...
姬幸斌; 李文兴; 吴建明
2012-01-01
部分充填混凝土窄幅钢箱连续组合梁桥是钢箱-混凝土组合梁与矩形钢管混凝土结构结合的一种新型组合结构梁桥。基于一般钢箱-混凝土连续组合梁桥中支座负弯矩区因混凝土翼板开裂而导致抗弯强度、局部稳定性不足的特点，提出了一种部分充填混凝土窄幅钢箱连续组合梁桥，并对其中支座负弯矩区的正截面强度和支座截面抗剪性能进行了塑性理论分析。% The narrow range of steel box continuous composite girder bridge that partially filled concrete is a new type of bridge which is composited by steel box-concrete composite girder and rectangular steel tube concrete. As the disadvantage that wing crack in negative moment region causing insufficient of bending strength and local stability of traditional steel box continuous composite girder bridge,a narrow range of steel box continuous composite girder bridge is presented. Then, the plasticity theory analysis is used on normal-section strength of bearing negative moment region and on cross-section support bearing shear performance.
M B ANOOP; K BALAJI RAO
2016-08-01
A methodology for performance evaluation of reinforced concrete bridge girders in corrosive environments is proposed. The methodology uses the concept of performability and considers both serviceability- and ultimate-limit states. The serviceability limit states are defined based on the degree of cracking (characterized by crack width) in the girder due to chloride induced corrosion of reinforcement, and the ultimate limit states are defined based on the flexural load carrying capacity of the girder (characterized in terms of rating factor using the load and resistance factor rating method). The condition of the bridge girder is specified by the assignment of a condition state from a set of predefined condition states. Generally, the classification of condition states is linguistic, while the condition states are considered to be mutually exclusive and collectivelyexhaustive. In the present study, the condition states of the bridge girder are also represented by fuzzy sets to consider the ambiguities arising due to the linguistic classification of condition states. A non-homogeneous Markov chain (MC) model is used for modeling the condition state evolution of the bridge girder with time. The usefulness of the proposed methodology is demonstrated through a case study of a severely distressed beam of the Rocky Point Viaduct. The results obtained using the proposed approach are compared with those obtained using conventional MC model. It is noted that the use of MC with fuzzy states leads to conservative decision making for the problem considered in the case study.
A EVALUATION OF THE EFFECTIVE PRESTRESS ON TIMBER CONCRETE COMPOSITE GIRDER BRIDGE
Araki, Shogo
In applying the glulam timber to the large-sized structures, the new types of connections have been developed. In presence, there are a few joint systems using steel plates and bolts. However, those systems are not always adequately satisfied with durability. Therefore, the new joint system by prestressing was developed. In Nagano prefecture, the timber-concrete composite bridge was provided as the standard design of timber bridges, and the joint system is by prestressing. In case of concrete girder, work of prestress decrease by elastic strain, creep, and etc. However, timber-concrete composite girder is not cleared numerically. In this study, we discussed the effective prestress on timber-concrete composite girder based on time-dependent of prestress checked in existing bridge, and we suggest the evaluation method of it.
A Simple Technique to Determine Interface Slip of Stud Connected SCC Girders
Rajasankar J.
2012-01-01
Full Text Available A simple technique is proposed to compute interface slip of stud connected steel-concrete composite (SCC girders based on the results of a flexure test. The technique makes use of relative longitudinal displacement of the concrete slab and steel beam to calculate the interface slip. In the flexure test of a SCC girder, a cost-effective instrumentation arrangement consisting of mechanical dial gauges is used to measure the relative longitudinal displacement. Responses measured from experiments on SCC girders conducted by the authors are used for numerical implementation and validation of the technique. Alternatively, interface slip is also evaluated by applying an analytical model which is based on first principles of mechanics. The values of interface slip computed by using the proposed technique are found to have close correlation with those of the analytical model. The effect of edge restraint on slip due to friction between steel and concrete is also studied
ZHANG Zhi-cheng; XIE Xu; ZHANG He; CHEN Heng-zhi
2007-01-01
A convenient approach is proposed for analyzing the ultimate load carrying capacity of concrete filled steel tubular (CFST) arch bridge with stiffening girders. A fiber model beam element is specially used to simulate the stiffening girder and CFST arch rib. The geometric nonlinearity, material nonlinearity, influence of the construction process and the contribution of prestressing reinforcement are all taken into consideration. The accuracy of this method is validated by comparing its results with experimental results. Finally, the ultimate strength of an abnormal CFST arch bridge with stiffening girders isinvestigated and the effect of construction method is discussed. It is concluded that the construction process has little effect on the ultimate strength of the bridge.
Welding of girders to insert plates of composite steel-concrete structure of tower in Kuwait
A. Lisiecki; J. Szlek; A. Klimpel
2007-01-01
Purpose: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible sources of the ...
Welding of girders to insert plates of composite steel-concrete structure
A. Klimpel; A. Lisiecki; J. Szlek
2007-01-01
Purpose: of this paper: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible s...
M. Škaloud; Zörnerová, M. (Marie)
2010-01-01
As a great part of steel structures are subjected to many times repeated loads (bridges, crane-supporting girders and the like), it is demonstrated, by means of the results of numerous experiments carried out by the authors in Prague, how the post-critical reserve of strength, the failure mechanism and the limit states of the webs of steel girders are affected by the cumulative damage process generated by the many times repeated character of loading, and how this phenomenon influences the des...
Sensitivity and statistical analysis within the elaboration of steel plated girder resistance
Melcher, J.; Škaloud, Miroslav; Kala, Z.; Karmazínová, M.
2009-01-01
Roč. 5, č. 2 (2009), s. 120-126. ISSN 1816-112X. [International conf. on steel and aluminium structures /6./. Oxford, 24.06.2007-27.06.2007] Institutional research plan: CEZ:AV0Z20710524 Keywords : steel structures * fatigue * sensitivity * imperfection * plated girder Subject RIV: JM - Building Engineering
Welding of girders to insert plates of composite steel-concrete structure
A. Klimpel
2007-09-01
Full Text Available Purpose: of this paper: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible sources of the concrete damage due to high welding temperature and stresses.Findings: It was shown that MMA welding at vertical-up position, by a rutile coated electrode of diameter 3,2 [mm], at welding current 110-120 [A], of the butt welds of tee-joints of girders and the insert plate does not cause any harmful and damaging effect to concrete, which temperature in a region of the contact with the bottom surface of the insert plate does not exceed 240 [˚C] during full cycle of welding. Tensile and compression stresses of concrete are transmitted mainly by anchoring bars, fixed in concrete and also by reinforcing fabric of concrete, and do not cause any cracks of concrete.Research limitations/implications: To achieve more consistent results of the numerical analysis of stresses and deformation distribution in the insert plate with experimental results, it is necessary to calculate plastic deformation of materials and also take into consideration nonlinear change of yield point (plasticity as a function of temperature.Practical implications: The technology was applied for welding of the girders to insert plates of the telecommunication tower in Kuwait.Originality/value: Welding procedure specification ensuring high quality of the welded joints of girders and insert plate of composite steel-concrete structure.
Welding of girders to insert plates of composite steel-concrete structure of tower in Kuwait
A. Lisiecki
2007-07-01
Full Text Available Purpose: A study of influence of preheating and MMA welding technique of tee-joints of plate girders to insert plates of a composite steel-concrete structure of the telecommunication tower, on the properties and quality of the concrete in the region of the insert plate has been carried out.Design/methodology/approach: Studies of thermo-mechanical phenomena during manual arc welding MMA of tee-joints between plate girders and insert plates were carried out to identify possible sources of the concrete damage due to high welding temperature and stresses.Findings: It was shown that MMA welding at vertical-up position, by a rutile coated electrode of diameter 3,2 [mm], at welding current 110-120 [A], of the butt welds of tee-joints of girders and the insert plate does not cause any harmful and damaging effect to concrete, which temperature in a region of the contact with the bottom surface of the insert plate does not exceed 240 [°C] during full cycle of welding. Tensile and compression stresses of concrete are transmitted mainly by anchoring bars, fixed in concrete and also by reinforcing fabric of concrete, and do not cause any cracks of concrete.Research limitations/implications: To achieve more consistent results of the numerical analysis of stresses and deformation distribution in the insert plate with experimental results, it is necessary to calculate plastic deformation of materials and also take into consideration nonlinear change of yield point (plasticity as a function of temperature.Practical implications: The technology was applied for welding of the girders to insert plates of the telecommunication tower in Kuwait.Originality/value: Welding procedure specification ensuring high quality of the welded joints of girders and insert plate of composite steel-concrete structure.
... Meeting Calendar Find an ENT Doctor Near You Voice Box (Laryngeal) Cancer Voice Box (Laryngeal) Cancer Patient Health Information News media ... laryngeal cancer can be severe with respect to voice, breathing, or swallowing. It is fundamentally a preventable ...
Sakaguchi, Junichi; Nakajima, Akinori; Suzuki, Yasuo
The sophisticated numerical analysis method is required to simulate the strain behavior of the reinforcement and the crack width of the RC slab, although many researches are conducted on the cracking behavior of the RC slab in the composite girder under the negative bending. In this paper, the numerical analysis method is constructed to evaluate the strain behavior of the reinforcement and the crack width of the RC slab in the steel-concrete composite girder subjected to the negative bending. The analysis method using the rigid body spring model takes into account the imperfect composite action between the steel girder and the RC slab, the bond between the reinforcement and the concrete, and the shrinkage of the concrete. As a result, it is confirmed that the analysis method can simulate the crack and the strain behavior of RC slab quantitatively in the steel-concrete composite girder under the negative bending.
Zevallos, E.; Hassanein, M.F.; Real Saladrigas, Esther; Mirambell Arrizabalaga, Enrique
2016-01-01
Because of public construction budgets were cut over the last few years, new bridge girders with corrugated webs to reduce the construction costs have become more widely studied and used. In spite that tapered bridge girders with corrugated webs (BGCWs) are used in modern bridges, their shear strength and behaviour rarely exists in literature. Based on available literature, the web of the linearly tapered BGCWs may be divided into three typologies with different structural response to shear f...
Mufti, Aftab; Jaeger, Leslie; Klowak, Chad; Kyriakopoulos, Nikolas; Bakht, Baidar; Tadros, Gamil
2007-04-01
Deflections of structures, such as bridge girders, are often the most difficult to monitor. Strain measurement is relatively simple with the use of electronic strain gauges, fiber optic sensors, or other strain measuring devices. This paper investigates two different methods for predicting or monitoring the deflection of a simply-supported full-scale bridge girder subjected to a partially distributed uniform load using strain measurements. A full-scale pre-stressed concrete bridge girder was instrumented and tested under a static monotonic load in the linear elastic range. This paper highlights the experimentally measured deflections along the length of one half of the girder and compares them to theoretically predicted deflections and deflections predicted using numerical integration along with harmonic analysis of curvatures determined from theoretical and observed experimental strains. Experimental test results indicate that estimating deflections from observed strains is feasible within the linear-elastic range of such girders. The methods outlined for predicting deflections of full-scale pre-stressed concrete bridge girders from observed strains are a valuable tool for structural engineers and for the periodic and continuous monitoring of civil structures such as bridges.
Li Jianzhong; Peng Tianbo; Xu yan
2008-01-01
An investigation of girder bridges on National Highway 213 and the Doujiangyan-Wenchuan expressway after the Wenchuan earthquake showed that typical types of damage included:span collapses due to unseating at expansion joints;shear key failure;and damage of the expansion joint due to the slide-induced large relative displacement between the bottom of the girder and the top of the laminated-rubber bearing.This slide,however,can actually act as a form of isolation for the substructure,and as a result,the piers and foundation of most of the bridges on state route 213 suffered minor damage.The exception was the Baihua Bridge,which suffered severe damage.Corresponding seismic design recommendations are presented based on this investigation.
Numerical Simulation for Progressive Collapse of Continuous Girder Bridge Subjected to Ship Impact
田力; 黄飞
2014-01-01
The three-stage simulation method based on LS-DYNA was introduced in this study to simulate the pro-gressive collapse of a continuous girder bridge after a ship-bridge collision. The pile-soil dynamic interaction and the initial stress and deformation of the whole bridge before the collision were considered. By analyzing the damage, de-formation, stress distribution and collapse process of the whole bridge, the results show that the displacement response of the cap beam lags behind the pile cap. The response order of the whole bridge’s components depends on their dis-tances from the collision region. The plastic deformation of soil around piles has a positive effect on delaying the fur-ther increase in the displacement of piles. The impacted pier’s losing stability and its superstructure’s excessive defor-mation are the main reasons leading to the progressive collapse of the continuous girder bridge.
Interactive Shear Buckling Of Plate Girder with Corrugated Web (Analytical Solution)
Prof.Dr:S.A.Tohamy; Ass.Prof.Dr:A.B.Saddek; Eng: Asmaa.Y.Hamed
2016-01-01
This paper presents analytical studies the elastic interactive shear buckling stress of corrugated steel web is calculated by all possible failure criteria (steel yielding, local and global buckling stresses), using Minimum Potential Energy Method to determine critical shear stress of local and global buckling of plate girder with corrugated webs. The results are compared with Finite element method (FEM) using ANSYS/V12. It found that the proposed equations are a good agreement with the resul...
Xiaoguang Deng; Muyu Liu
2015-01-01
Based on the nonlinear stability analysis method, the 3D nonlinear finite element model of a composite girder cable-stayed bridge with three pylons is established to research the effect of factors including geometric nonlinearity, material nonlinearity, static wind load, and unbalanced construction load on the structural stability during construction. Besides, the structural nonlinear stability in different construction schemes and the determination of temporary pier position are also studied...
Performance of Bridge Decks and Girders with Lightweight Aggregate Concrete, v. 2 of 2
Ramirez, J.A.; Olek, J.; Rolle, Eric Joseph; Malone, Brian Joseph
2000-01-01
Structural lightweight concrete is a very versatile material and Haydite and Minergy lightweight aggregates can be utilized in the mixture development of concrete for use in girders and decks in bridges. More widespread use of lightweight aggregates (LWA) would result in savings in construction cost due to considerable dead load reduction. The materials phase of this research study evaluated the fresh concrete properties (slump, unit weight, and air content), the mechanical properties of ...
Strain-Based Evaluation of a Steel Through-Girder Railroad Bridge
Daumueller, Andrew N.; David V. Jáuregui
2012-01-01
In the state of New Mexico (USA), passenger rail began in 2008 between Belen and Santa Fe on the Rail Runner, following the acquisition of about 100 miles of existing rail and related infrastructure. Many of the bridges on this route are over 100 years old and contain fatigue prone details. This study focuses on a steel through-girder bridge along this corridor. To accurately evaluate these structures for load carrying capacity and fatigue, an accurate analytical model is required. Accordingl...
Statistical and sensitivity analysis within the elaboration of steel plated girders
Melcher, J.; Škaloud, Miroslav; Kala, Z.; Karmazínová, M.
Oxford : Oxford Brookes University, 2007 - (Beale, R.), s. 309-315 ISBN 978-0-9556254-0-4. [Steel and aluminium structures ICSAS´07 /6./. Oxford (GB), 24.07.2007-27.07.2007] Grant ostatní: GA ČR(CZ) GA103/05/2059; GA ČR(CZ) GA103/07/1067 Institutional research plan: CEZ:AV0Z20710524 Keywords : steel plate girders * initial imperfection * web breathing Subject RIV: JM - Building Engineering
Study the vibration and dynamic response of the dipole girder system for CSNS/RCS
Renhong, Liu; JunSong, Zhang; GuangYuan, Wang
2015-01-01
China Spallation Neutron Source is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts an H- linac and a rapid cycling synchrotron. The RCS accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25Hz. The dipole of the CSNS RCS is operated at a 25 Hz sinusoidal alternating current which causes severe vibrate. The vibration will influence the long term safety and reliable operation of the magnet. The dipole of the CSNS RCS is an active vibration equipment which is different from the ground vibration accelerator. It is very important to design and study the dynamic characteristics of the dipole girder system. This paper takes the dipole and girder as a specific model system, a method for studying the dynamic characteristics of the system is put forward by combining theoretical calculation with experimental testing. The modal parameters with and without vibration isolator of the dipole girder system are obtain through ANSYS s...
The vibration research of the AC dipole-girder system for CSNS/RCS
Renhong, Liu; Huamin, Qu; Ling, Kang; Motuo, Wang; Guangyuan, Wang; Haijing, Wang
2013-01-01
China spallation neutron source(CSNS) is a high intensity proton accelerator based facility, and its accelerator complex includes two main parts: an H- linac and a rapid cycling synchrotron(RCS). The rcs accumulates the 80MeV proton beam, and accelerates it to 1.6GeV, with a repetition rate of 25 Hz. The AC dipole of the RCS is operated at a 25Hz sinusoidal alternating current which causes severe vibration. The vibration will influence the long-term safety and reliable operation of the magnet. The dipole magnet of RCS is active vibration equipment which is different with ground vibration accelerator. It is very important to design and research the dynamic characteristic of the dipole-girder system. This paper takes the dipole and girder as a specific model system, a method for researching the dynamic characteristic of the system is put forward by combining theoretical calculation with experimental testing. The ansys simulation method plays a very important role in the girder structure design stage. With the m...
Finite Element Analysis of the Effect of Crack Depth and Crack Opening On the Girder
Md. Kamrul Hassan
2011-01-01
Full Text Available In order to identify the effect of crack depth and opening on the girder, finite element method (FEM has been used in this paper. In FE analysis, six nodded two dimensional plane elements (PLANE-2 are considered. Each node has two degree of freedom such as UX and UY. For the plane elements, a plane stress width/thickness option is chosen. For analytical model of crack of the concrete bridge girder, crack opening was increased from 0.2 mm to 1mm at an interval 0.2 mm and crack depth also increased from 30 mm to 150 mm at an interval 30 mm. The models were discreatized by a triangular mesh and convergence test was executed to obtain satisfactory results from the Plane-2 element. From the numerical result, it is seen that the principal stress become a higher with increased the crack depth and also crack opening with respect to load increasing. But the crack depth at 90 mm and crack opening at 0.6 mm, it has more effect on the girder because the stress concentration is higher than other crack depth and opening.
Stenholt, Rasmus; Madsen, Claus B.
2011-01-01
Enabling users to shape 3-D boxes in immersive virtual environments is a non-trivial problem. In this paper, a new family of techniques for creating rectangular boxes of arbitrary position, orientation, and size is presented and evaluated. These new techniques are based solely on position data...
Construction engineering of steel tub-girder bridge systems for skew effects
Jimenez Chong, Juan Manuel
Closed structural sections, such as those having circular, rectangular or trapezoidal shape, possess high rotational rigidity when compared to open sections such as I-girders. The high torsional rigidity of closed sections makes them ideal for use in highly curved bridges. In this case, the geometry of the bridge results in large torsional forces. Because of structural efficiency and economy reasons, most of these closed-section bridges consist of a trapezoidal cross-section, with a top concrete slab and bottom and side steel plates. The slab is cast after the steel is erected and thus a system of internal diaphragms and braces is necessary to stabilize the system during erection. During the steel erection and the early stages of the concrete deck placement, the section can be considered as quasi-closed as the top concrete flange has not been cast or is not yet effective. During steel erection, undetermined and/or large torsional forces and/or displacements may result in fit-up problems requiring large stresses to overcome. During concrete deck placement, the undetermined displacements can affect the control of the deck thickness and the final deck geometry, such as the alignment of deck joints and the matching of stages in phased constructions projects. Due to the interactions between their various components, the behavior of curved and skewed tub-girder bridges is significantly more complex than that of straight bridges. When skewed supports are used in tub-girders, the interaction of the girder bending rotations and the displacement constraints induced by the skewed support diaphragms causes twisting of the girders at the supports. These twist rotations introduce additional torques into the system. Both curvature and skew can cause design and construction difficulties, especially at the supports, where the corresponding steel dead load deflections and the large torsional stiffness of the girders may lead to large fit-up forces. Currently, the general
Lutz, Marilyn; Gallucci, Laura
2005-01-01
The paper describes the Maine Music Box and examines its potential as a tool for teaching and learning music. Pedagogical concepts are demonstrated using MIDI, Scorch, image and streaming video files.
The larynx, or voice box, is located in the neck and performs several important functions in the body. The larynx is involved in swallowing, breathing, and voice production. Sound is produced when the air which ...
A numerical investigation on the fire response of a steel girder bridge
Paya-Zaforteza, I.; Garlock, Maria E.M.
2012-01-01
The response of bridges subject to fire is an under researched topic despite the number of bridge failures caused by fire. Since available data shows that steel girder bridges are especially vulnerable to fire, this paper delves into their fire response by analyzing with a 3D numerical model the response of a typical bridge of 12.20 m span length. A parametric study is performed considering: (1) two possibilities for the axial restraint of the bridge deck, (2) four types of structural steel f...
Methods for determination of ultimate load of eccentrically patch loaded steel I-girders
Šćepanović, B.
2014-12-01
Full Text Available Experimental tests show that most eccentrically patch loaded steel I-girders have a collapse mode quite different from that of centrically loaded girders. Concerning engineering practice, the most important difference between collapse modes is in ultimate load. The reduction in ultimate load with an increase in load eccentricity is obvious in some eccentrically loaded girders. Under certain circumstances, for a certain combination of influential parameters, eccentrically loaded girders behave as if loaded in the web plane, with no or no significant reduction in ultimate load due to load eccentricity. Dealing with such a big number of mutually dependant parameters that influence collapse mode and level of ultimate load reduction due to load eccentricity, still without theoretical formulation of collapse mechanism, two approaches for ultimate load determination are analysed: empirical mathematical expressions and artificial neural networks forecast models. Results of two procedures are compared. Recommendations for application in engineering practice are given.Las pruebas experimentales muestran que la mayoría de vigas en I de acero cargadas excéntricamente tienen un modo de colapso muy diferente del de las vigas cargadas centradas. En cuanto a la práctica de ingeniería, la diferencia más importante entre los modos de colapso es la carga final. La reducción de la carga última con un aumento de la excentricidad de carga es evidente en algunas vigas cargadas excéntricamente, mientras que bajo ciertas circunstancias, para una determinada combinación de parámetros influyentes, las vigas cargadas excéntricamente se comportan como si se carga en el plano del alma, con ninguna reducción significativa en la carga última debido a la carga excéntrica. Se analizan dos métodos para la determinación de la carga máxima: expresiones matemáticas empíricas y redes neuronales artificiales. Los resultados de ambos procedimientos se comparan. Se
Some remarks in regard to the fatigue analysis of steel plate girders with breathing webs
Maquoi, R.; Škaloud, Miroslav
Praha : České Vysoké Učení technické v Praze, 2003 - (Studnička, J.), s. 397-402 ISBN 80-01-02747-3. [Česko-slovenská konference s mezinárodní účastí - Ocelové konstrukce a mosty /20./. Praha (CZ), 17.09.2003-20.09.2003] R&D Projects: GA AV ČR IAA2071102 Institutional research plan: CEZ:AV0Z2071913 Keywords : steel plate girders * fatigue limit state * fatigue crack Subject RIV: JM - Building Engineering
刘扬; 王东东
2013-01-01
Guided by the energy variational principle and based on the different longitudinal displacements of three parabolas,the basic differential equation of the shear lag of cantilever box girders is obtained,and its feasibility is proved by using the finite difference method.The method is applied to analyze the shear lag effect of cantilever box girder under the longitudinal prestressing of equivalent loaf.Based on the ANSYS,a model which features that the box girder is built and simulated by Solid 95,and the prestressed steel is simulated by Link 10.Later,the model is used to analyze the coefficient distribution rule of the shear lag of the box girder under the longitudinal prestressing,and then this rule is compared with the result from finite difference method.This comparison proves the applicability of the difference method in the study of the shear lag effect of the box girder under longitudinal prestressing of equivalent loaf,and longitudinal prestressing's effects on the shear lag effect of beam is also analyzed.%选取3次抛物线变化的纵向位移,通过能量变分原理得到悬臂箱梁的剪力滞基本微分方程,再利用有限差分法进行求解,将该方法用于分析纵向预应力等效荷载作用下的悬臂箱梁剪力滞效应.运用ANSYS有限元软件建立模型,采用Solid 95单元模拟箱梁,采用Link8单元模拟预应力钢束,分析在纵向预应力作用下箱梁剪滞系数分布规律并与差分法求解的结果进行对比.经过对比,验证了差分法求解纵向预应力等效荷载作用下箱梁剪滞效应的可行性,同时分析了纵向预应力对箱梁剪滞效应的影响.
赵建; 郑舟军
2013-01-01
组合梁仿真分析时将多个剪力钉简化成一个等效剪力群钉进行模拟,不能准确得到每个剪力钉的受力情况.为解决此问题,根据实桥集束式剪力钉布置方式制作剪力群钉推出试件,并进行推出试验,得知群钉中最不利的单个剪力钉承担了32％～37％的总剪力(平均值仅为25％);由大跨度组合箱梁整体模型计算得到剪力群钉受力均值、钢-混凝土相对位移及钢梁与混凝土桥面板的受力状况;根据剪力群钉荷载分配比例对组合梁整体计算得到的剪力钉计算结果进行修正.结果表明,将剪力群钉受力均值换算得到剪力钉受力极值的方法,可实现对大跨度组合梁及其剪力钉的精确仿真分析.%When the simulation analysis of a composite girder is made,the way of simplifying the multiple shear studs of the girder into the equivalent group shear studs can not exactly acquire the force condition of each stud.To solve the problem,the push-out specimen of the group shear studs was fabricated according to the clustering layout of the shear studs of the practical bridge,the push out test for the specimen was carried out and it was consequently known that the single stud in the group shear studs under the worst force condition sustained 32％～37％ of the total shear force (while the average value was 25％ only).From the calculation of the integral model of the long span composite box girder,the force average values of the group shear studs,the relative displacement of the steel and concrete and the force conditions of the steel girder and concrete deck slabs were acquired and with reference to the load distribution ratios of the group shear studs,the calculation results of the shear studs were modified.The results of the calculation and modification demonstrate that by way of converting from the force average values of the group shear studs to the force ultimate values of the shear studs,the accurate simulation analysis of
Strain-Based Evaluation of a Steel Through-Girder Railroad Bridge
Andrew N. Daumueller
2012-01-01
Full Text Available In the state of New Mexico (USA, passenger rail began in 2008 between Belen and Santa Fe on the Rail Runner, following the acquisition of about 100 miles of existing rail and related infrastructure. Many of the bridges on this route are over 100 years old and contain fatigue prone details. This study focuses on a steel through-girder bridge along this corridor. To accurately evaluate these structures for load carrying capacity and fatigue, an accurate analytical model is required. Accordingly, four models were developed to study the sensitivity of a bridge in New Mexico to floor-system connection fixity and the ballast. A diagnostic load test was also performed to evaluate the accuracy of the finite-element models at locations of maximum moments. Comparisons between the simulated and measured bridge response were made based on strain profiles, peak strains, and Palmgren-Miner’s sums. It was found that the models including the ballast were most accurate. In most cases, the pinned ended models were closer to the measured strains. The floor beams and girders were relatively insensitive to the ballast and end conditions of the floor-system members, whereas the stringers were sensitive to the modeling of the ballast.
Coupled Vibration of Long-Span Railway Curved Girder Bridges and Vehicles
Shan Deshan; Li Qiao
2005-01-01
The structure of a long curved girder bridge is represented with a three-dimensional curved finite element model. Each 4-axle vehicle is modeled by a dynamic system of 35 degrees of freedom. The random irregularities of the track are generated from a power spectral density function under the given track condition. The dynamic interaction between the bridge and train is realized through the contact forces between the wheels and track. Then based on these models, the coupled equations of motion are solved by applying the time-integration and iteration techniques to the coupled system. The proposed formulation and the associated computer program are then applied to a real curved girder bridge. The dynamic responses of the bridge-vehicle system and the derailments and offload factors related to the riding and running safeties of vehicles are computed. The results show that the formulation presented in this paper can well predict dynamic behaviors of both bridge and train with reasonable computation efforts.
Xiaoguang Deng
2015-01-01
Full Text Available Based on the nonlinear stability analysis method, the 3D nonlinear finite element model of a composite girder cable-stayed bridge with three pylons is established to research the effect of factors including geometric nonlinearity, material nonlinearity, static wind load, and unbalanced construction load on the structural stability during construction. Besides, the structural nonlinear stability in different construction schemes and the determination of temporary pier position are also studied. The nonlinear stability safety factors are calculated to demonstrate the rationality and safety of construction schemes. The results show that the nonlinear stability safety factors of this bridge during construction meet the design requirement and the minimum value occurs in the maximum double cantilever stage. Besides, the nonlinear stability of the structure in the side of edge-pylon meets the design requirement in the two construction schemes. Furthermore, the temporary pier can improve the structure stability, effectively, and the actual position is reasonable. In addition, the local buckling of steel girder occurs earlier than overall instability under load in some cable tension stages. Finally, static wind load and the unbalanced construction load should be considered in the stability analysis for the adverse impact.
A Cyber-Physical System for Girder Hoisting Monitoring Based on Smartphones.
Han, Ruicong; Zhao, Xuefeng; Yu, Yan; Guan, Quanhua; Hu, Weitong; Li, Mingchu
2016-01-01
Offshore design and construction is much more difficult than land-based design and construction, particularly due to hoisting operations. Real-time monitoring of the orientation and movement of a hoisted structure is thus required for operators' safety. In recent years, rapid development of the smart-phone commercial market has offered the possibility that everyone can carry a mini personal computer that is integrated with sensors, an operating system and communication system that can act as an effective aid for cyber-physical systems (CPS) research. In this paper, a CPS for hoisting monitoring using smartphones was proposed, including a phone collector, a controller and a server. This system uses smartphones equipped with internal sensors to obtain girder movement information, which will be uploaded to a server, then returned to controller users. An alarming system will be provided on the controller phone once the returned data exceeds a threshold. The proposed monitoring system is used to monitor the movement and orientation of a girder during hoisting on a cross-sea bridge in real time. The results show the convenience and feasibility of the proposed system. PMID:27399710
A Cyber-Physical System for Girder Hoisting Monitoring Based on Smartphones
Han, Ruicong; Zhao, Xuefeng; Yu, Yan; Guan, Quanhua; Hu, Weitong; Li, Mingchu
2016-01-01
Offshore design and construction is much more difficult than land-based design and construction, particularly due to hoisting operations. Real-time monitoring of the orientation and movement of a hoisted structure is thus required for operators’ safety. In recent years, rapid development of the smart-phone commercial market has offered the possibility that everyone can carry a mini personal computer that is integrated with sensors, an operating system and communication system that can act as an effective aid for cyber-physical systems (CPS) research. In this paper, a CPS for hoisting monitoring using smartphones was proposed, including a phone collector, a controller and a server. This system uses smartphones equipped with internal sensors to obtain girder movement information, which will be uploaded to a server, then returned to controller users. An alarming system will be provided on the controller phone once the returned data exceeds a threshold. The proposed monitoring system is used to monitor the movement and orientation of a girder during hoisting on a cross-sea bridge in real time. The results show the convenience and feasibility of the proposed system. PMID:27399710
A Cyber-Physical System for Girder Hoisting Monitoring Based on Smartphones
Ruicong Han
2016-07-01
Full Text Available Offshore design and construction is much more difficult than land-based design and construction, particularly due to hoisting operations. Real-time monitoring of the orientation and movement of a hoisted structure is thus required for operators’ safety. In recent years, rapid development of the smart-phone commercial market has offered the possibility that everyone can carry a mini personal computer that is integrated with sensors, an operating system and communication system that can act as an effective aid for cyber-physical systems (CPS research. In this paper, a CPS for hoisting monitoring using smartphones was proposed, including a phone collector, a controller and a server. This system uses smartphones equipped with internal sensors to obtain girder movement information, which will be uploaded to a server, then returned to controller users. An alarming system will be provided on the controller phone once the returned data exceeds a threshold. The proposed monitoring system is used to monitor the movement and orientation of a girder during hoisting on a cross-sea bridge in real time. The results show the convenience and feasibility of the proposed system.
The BOXES Methodology Black Box Dynamic Control
Russell, David W
2012-01-01
Robust control mechanisms customarily require knowledge of the system’s describing equations which may be of the high order differential type. In order to produce these equations, mathematical models can often be derived and correlated with measured dynamic behavior. There are two flaws in this approach one is the level of inexactness introduced by linearizations and the other when no model is apparent. Several years ago a new genre of control systems came to light that are much less dependent on differential models such as fuzzy logic and genetic algorithms. Both of these soft computing solutions require quite considerable a priori system knowledge to create a control scheme and sometimes complicated training program before they can be implemented in a real world dynamic system. Michie and Chambers’ BOXES methodology created a black box system that was designed to control a mechanically unstable system with very little a priori system knowledge, linearization or approximation. All the method need...
Wang Changfeng
2014-10-01
Full Text Available During an earthquake, the nonlinearity of the bridge structure mainly occurs at the supports, bridge piers and restrainers. When entering nonlinear stage, members of the bridge structure affect the elasto-plastic seismic response of the whole structure to a certain extent; for multi-span continuous bridges, longitudinal restrainers can be installed on the movable piers to optimise the distribution of seismic force and enable the movable piers to bear a certain amount of seismic effect. In order to evaluate the effect of nonlinearity of restrainer and supports on the elasto-plastic seismic response of continuous girder bridge, analytical models of continuous girder bridge structure considering the nonlinearity of movable supports, restrainers and bridge piers were built and the nonlinear time history analysis was conducted to evaluate the effect of nonlinearity of restraining devices and supports on the elasto-plastic seismic response of continuous girder bridge. Relevant structural measures and recommendation were made to reduce the seismic response of the fixed piers of the continuous girder bridge.
Bertsche, David; The ATLAS collaboration; Welch, Steven; Smith, Dale Shane; Che, Siinn; Gan, K.K.; Boyd, George Russell Jr
2015-01-01
The opto-box is a custom mini-crate for housing optical modules, which process and transfer optoelectronic data. The system tightly integrates electrical, mechanical, and thermal functionality into a small package of size 35x10x8 cm^3. Special attention was given to ensure proper shielding, grounding, cooling, high reliability, and environmental tolerance. The custom modules, which incorporate Application Specific Integrated Circuits (ASICs), were developed through a cycle of rigorous testing and redesign. In total, fourteen opto-boxes have been installed and loaded with modules on the ATLAS detector. They are currently in operation as part of the LHC run 2 data read-out chain.
徐升桥; 刘永锋
2013-01-01
京新上地桥的曲线混凝土主梁采用单点顸推法施工,顶推总重250 000 kN,顶推距离213 m,顶推过程最大悬臂长度63 m.钢导梁预埋于主梁前端,通过剪力连接件和混凝土箱梁连接成整体,以传递顶推过程中的弯矩和剪力.对钢-混凝土过渡段顶、底、腹板的连接件受力性能进行设计分析,并建立实体模型详细分析最不利工况下关键部位的局部应力,结果表明界面连接可靠,钢-混凝土过渡段变形协调、应力分布均匀,设计合理.%Single-point incremental launching method is employed to construct the curved concrete main girder of Shangdi Bridge on Beijing - Xinjiang Expressway. During the incremental launching construction, the total launching weight, distance and maximum cantilever length is respectively 25 000 t, 213 m and 63 m. In order to transfer bending moment and shear force, the steel launching nose is pre-embedded in the front end of the concrete main girder, and is integrally connected with the concrete box girder by shear connectors. For the steel-concrete transition section; mechanical performance of connectors at the top, bottom and web slabs are analyzed firstly; and then, local stress at key positions under the most unfavorable conditions are precisely analyzed by means of solid model. The analysis results show that: connection of the interface is reliable, deformation of the steel-concrete transition section is compatible, and stress distribution is uniform, which indicate that the design is reasonable.
Raiser, Lynne; D'Zamko, Mary Elizabeth
1984-01-01
Using environmental materials (such as the phone book and placemats from fast food restaurants) can be a motivating way to teach learning disabled students skills and concepts, as shown in an approach to reading, math, science and nutrition, and social studies instruction using a JELL-O brand gelatin box. (CL)
Hydrophobic, Porous Battery Boxes
Bragg, Bobby J.; Casey, John E., Jr.
1995-01-01
Boxes made of porous, hydrophobic polymers developed to contain aqueous potassium hydroxide electrolyte solutions of zinc/air batteries while allowing air to diffuse in as needed for operation. Used on other types of batteries for in-cabin use in which electrolytes aqueous and from which gases generated during operation must be vented without allowing electrolytes to leak out.
A system for posting objects into closed containers, such as glove boxes, is described in which the bag used, preferably made of plastic, does not have to be fitted and sealed by the operator during each posting operation. (U.K.)
Jones, AnnMarie
2002-01-01
Presents a multicultural project used with fourth-grade students in which they created a three-dimensional totem pole using leftover cereal boxes. Discusses in detail how to create the totem pole. Explains that students learned about Northwest American Indians in class. (CMK)
This magnetic tape contains the FORTRAN source code, sample input data, and sample output data for the Photochemical Box Model (PBM). The PBM is a simple stationary single-cell model with a variable height lid designed to provide volume-integrated hour averages of O3 and other ph...
Evaluation of the Structure Stability of a Plate Girder Bridge Using MIDAS Structure Analysis
Kim, Eui Soo; Kim, Jong Hyuk [National Forensic Service, Wonju (Korea, Republic of)
2014-04-15
Recently, as a means of resolving the issue of legal liability in the event of an accident or a disaster, a wide variety of simulation techniques, such as structural and structure-fluid interaction analysis, have been used in the field of forensic engineering. The plate girder bridge discussed in this paper was being constructed between a pier and an abutment to expand an existing bridge, but an accident whereby the bridge overturned occurred at the end of the concrete laying process for a protective wall. This accident was caused by additional loads not being considered at the time of the design as well as the actual construction being different from the design. The additional loads ultimately generated a negative support force. In this study, we determined the cause of the accident by comparing the structural stability of the original design with that of the additional, non-conforming construction using MIDAS structural analysis.
Prediction of Fatigue Life of a Continuous Bridge Girder Based on Vehicle Induced Stress History
V.G. Rao
2003-01-01
Full Text Available The fatigue damage assessment of bridge components by conducting a full scale fatigue testing is often prohibitive. A need, therefore, exists to estimate the fatigue damage in bridge components by a simulation of bridge-vehicle interaction dynamics due to the action of the actual traffic. In the present paper, a systematic method has been outlined to find the fatigue damage in the continuous bridge girder based on stress range frequency histogram and fatigue strength parameters of the bridge materials. Vehicle induced time history of maximum flexural stresses has been obtained by Monte Carlo simulation process and utilized to develop the stress range frequency histogram taking into consideration of the annual traffic volume. The linear damage accumulation theory is then applied to calculate cumulative damage index and fatigue life of the bridge. Effect of the bridge span, pavement condition, increase of vehicle operating speed, weight and suspension characteristics on fatigue life of the bridge have been examined.
Roessiger, R.
1987-01-01
The TGL 13472 industrial standard calculation method is explained for steel girder stability and fatigue with the example of a bucket wheel excavator boom. The excavator operates in block mining with the bucket wheel boom slewing 90 degrees. Bucket wheel cutting and girder load forces are determined by a computer program. Their values are listed. Equations for maximum load fatigue and operating strength factor are given along with stability results. Time required for calculations is regarded as reasonable. 4 refs.
Decommissioning a small glove box
An account is given of dismantling a fuel fabrication glove box using simple tooling. The fissile content of the box was first measured by several non-destructive techniques. After cleaning, the box was dismantled using hand tools and finally packed for disposal. A record of operator radiation doses, the time taken for each stage of the operation and packing information is given. (author)
Bertsche, David; The ATLAS collaboration
2015-01-01
The opto-box is a custom mini-crate for housing optical modules, which process and transfer optoelectronic data. Many novel solutions were developed for the custom design and manufacturing. The system tightly integrates electrical, mechanical, and thermal functionality into a small package of size 35x10x8 cm$^{3}$. Special attention was given to ensure proper shielding, grounding, cooling, high reliability, and environmental tolerance. The custom modules, which incorporate Application Specific Integrated Circuits (ASICs), were developed through a cycle of rigorous testing and redesign. In total, fourteen opto-boxes have been installed and loaded with modules on the ATLAS detector. They are currently in operation as part of the LHC run 2 data read-out chain.
Nielsen, Peter Vilhelm
The velocity level in a room ventilated by jet ventilation is strongly influenced by the supply conditions. The momentum flow in the supply jets controls the air movement in the room and, therefore, it is very important that the inlet conditions and the numerical method can generate a satisfactor...... description of this momentum flow. The Box Method is a practical method for the description of an Air Terminal Device which will save grid points and ensure the right level of the momentum flow....
Melacci, Stefano; Gori, Marco
2013-11-01
Supervised examples and prior knowledge on regions of the input space have been profitably integrated in kernel machines to improve the performance of classifiers in different real-world contexts. The proposed solutions, which rely on the unified supervision of points and sets, have been mostly based on specific optimization schemes in which, as usual, the kernel function operates on points only. In this paper, arguments from variational calculus are used to support the choice of a special class of kernels, referred to as box kernels, which emerges directly from the choice of the kernel function associated with a regularization operator. It is proven that there is no need to search for kernels to incorporate the structure deriving from the supervision of regions of the input space, because the optimal kernel arises as a consequence of the chosen regularization operator. Although most of the given results hold for sets, we focus attention on boxes, whose labeling is associated with their propositional description. Based on different assumptions, some representer theorems are given that dictate the structure of the solution in terms of box kernel expansion. Successful results are given for problems of medical diagnosis, image, and text categorization. PMID:24051728
Baumann, Gregg W.
1997-01-01
Approved for public release; distribution unlimited. The objective of this study is to investigate structural shadow zones encountered in shipbuilding design using the I-DEAS (Integrated Design Engineering Analysis Software) software. The term 'shadow zone' refers to areas of low stress concentrations that are caused by lines of stress bending around structural discontinuities. Two ship design situations frequently encountered that result in shadow zones are hull girder penetrations and sh...
Škaloud, Miroslav; Melcher, J.; Kala, J.; Kala, Z.
Lisabon : Rolo & Filhos, Indústrias Gráficas, S.A, 2009 - (Ambrósio, J.; Silva, M.), s. 645-646 ISBN 978-989-96264-2-3. [ESMC2009. Lisabom (PT), 07.09.2009-11.09.2009] Grant ostatní: GA ČR(CZ) GA103/08/0275 Institutional research plan: CEZ:AV0Z20710524 Keywords : economic-fabrication steel girders * web initial curvature * straightening Subject RIV: JM - Building Engineering
Performances of super-long span prestressed cable-stayed bridge with CFRP cables and RPC girder
Fang Zhi; Fan Fenghong; Ren Liang
2013-01-01
To discuss the applicability of advanced composite carbon fiber reinforced polymer (CFRP) and ultra-high performance concrete reactive powder concrete (RPC) in super-long span cable-stayed bridges , taking a 1 008 m cable-stayed bridge with steel girders and steel cables as an example,a new cable-stayed bridge in the same span with RPC girders and CFRP cables was designed,in which the cable’s cross section was determined by the principle of equivalent cable capacity and the girder’s cross section was determined in virtual of its stiffness, shear capacity and local stability. Based on the methods of finite element analysis,the comparative analysis of these two cable-stayed bridge schemes about static performances,dynamic performances,stability and wind resis-tance behavior were carried out. The results showed that it was feasible to form a highly efficient,durable concrete cable-stayed bridge with RPC girders and CFRP cables and made its applicable span range expand to 1 000 m long around.
Optimizationd sign fo erhead raveling rane's box irder%桥式起重机箱形梁的优化设计
田国富; 孙书慧; 程艳辉
2000-01-01
箱形梁桥式起重机是起重机械的一种类型，广泛应用于各厂矿企业。其主要承载结构箱形梁的重量占整机重量的比重最大，为提高整机性能，降低能耗，在对整机受力分析基础上，建立了优化模型，并应用其进行了具体优化设计。%The welded box girder of overhead traveling crane is one kind of cranes used in general plants.The welded box girder is the major loaded part and its weight takes the major part of the machine’s total weight.In order to improve the capacity of the cranes, a kind of optimization model based on the analyzing of loading condition and a optimization design according to it is done.
Hale, Layton C.; Malsbury, Terry; Hudyma, Russell M.; Parker, John M.
2000-01-01
A projection optics box or assembly for use in an optical assembly, such as in an extreme ultraviolet lithography (EUVL) system using 10-14 nm soft x-ray photons. The projection optics box utilizes a plurality of highly reflective optics or mirrors, each mounted on a precision actuator, and which reflects an optical image, such as from a mask, in the EUVL system onto a point of use, such as a target or silicon wafer, the mask, for example, receiving an optical signal from a source assembly, such as a developed from laser system, via a series of highly reflective mirrors of the EUVL system. The plurality of highly reflective optics or mirrors are mounted in a housing assembly comprised of a series of bulkheads having wall members secured together to form a unit construction of maximum rigidity. Due to the precision actuators, the mirrors must be positioned precisely and remotely in tip, tilt, and piston (three degrees of freedom), while also providing exact constraint.
Description is given of a device for simply and rapidly assembling and dissassembling the filters used inside sealed enclosures, such as glove-boxes and shielded cells equipped with nippers or manipulators, said filters being of the type comprising a cylindrical casing containing a filtering member, the upper portion of said casing being open so as to allow the gases to be cleaned to flow in, whereas the casing bottom is centrally provided with a hole extended outwardly by a threaded collar on which is screwed a connecting-sleeve to be fixed to the mouth of a gas outlet pipe. To a yoke transverse bar is welded a pin which can be likened to a bent spring-blade, one arm of which welded to said transverse bar, is rectilinear whereas its other arm is provided with a boss cooperating with a cavity made in a protrusion of said pipe, right under the mouth thereof
Briegel, C; Hendricks, B; King, C; Lackey, S; Neswold, R; Nicklaus, D; Patrick, J; Petrov, A; Rechenmacher, R; Schumann, C; Smedinghoff, J
2012-01-01
The Accelerator Control System at Fermilab has evolved to enable this relatively large control system to be encapsulated into a "box" such as a laptop. The goal was to provide a platform isolated from the "online" control system. This platform can be used internally for making major upgrades and modifications without impacting operations. It also provides a standalone environment for research and development including a turnkey control system for collaborators. Over time, the code base running on Scientific Linux has enabled all the salient features of the Fermilab's control system to be captured in an off-the-shelf laptop. The anticipated additional benefits of packaging the system include improved maintenance, reliability, documentation, and future enhancements.
COMPARATIVE ANALYSIS OF MODELS OF RAILWAY LOADS C14 AND LM71 FOR GIRDER BRIDGES
V. Artomov
2014-01-01
Full Text Available Purpose. The article analyzes the railway load LM71 for the purpose of its application in national design projects of the railway girder bridges. Purpose of the article is harmonization of national design codes of enginnering structures with the European standards (Eurocodes. Methodology. Analytical calculation methods (influence lines, the matrix analysis and computer programming are used in the article. Findings. Deflected mode parameters of the railway bridges under the influence of loads C14 and LM71 have certain differences. The extent of these differences depends on length, material of drift structures and also on dynamic coefficients. These dependences should be considered in national design codes and in harmonized with Eurocodes standards. In the further researches relationships between load C14 and models SW, HSLM taking into account various dynamic effects and trains speedis planned to determine. Originality. The presented results, in particular deflected mode parameters (including loads with dynamic coefficients, obtained for the first time. Practical value. Results of research are used in National Annex to the National Standard of Ukraine NSTU-N B EN 1991-2:2010. Eurocode 1. Actions on structures. Part 2. Traffic loads on bridges (EN 1991-2:2003.
Case Study Evaluation of Steel Girder of Bridge Replacement by GFRP
Parinaz Arashnia
2015-09-01
Full Text Available Nowadays, because of the steel desired tensile, compressive strength, and light weight especially in the large spans, it has been widely popular in the bridge construction. On the other hand, there are some disadvantages including corrosion, buckling and weaknesses in the higher temperatures, and unsuitable weld which would be resolved using Fibres Reinforced Polymer (FRP profiles. The FRP is a remarkable class of composite polymers that can improve structural elements behaviours like as resistance against corrosion, fire, electricity, and magnetic fields. In this paper, composite GFRP & UHF beams along with the behaviour of I-shaped beam were studied and discussed under the point loads using numerical models, results were compared and verified with the experimental tests whereas two different beams were modelled and verified under static progressive loading performed with ABAQUS as an FEM base software. Finally, Moddares-Haqqani that is a steel girder bridge has been modeled by SAP software and maximum displacement has been determined. Then 4 GFRP beams modeled by ABAQUS software and best section has been determined. Beams are under dead and live loading. Purposes of this paper are evaluating of use of GFRP materials as a basic material in construction process and compare this operation with steel. Results shown that because of lower modulus of elasticity in GFRP compare with steel, displacement has increase in GFRP beams and hence beams dimension must be increase to limit displacement.
Real-time damage monitoring scheme in PSC girder bridge using output-only acceleration data
Kim, Jeong-Tae; Park, Jae-Hyung; Do, Han-Sung; Lee, Jung-Mi
2007-04-01
Artificial neural networks (ANNs) have been increasingly utilized for structural health monitoring (SHM) due to the advantage that it needs only a few training data to detect damage in structures. In this study, a new damage monitoring method using a set of parallel ANNs and acceleration signals is developed for alarming locations of damage in PSC girder bridges. First, theoretical backgrounds are described. The problem addressed in this paper is defined as the stochastic process. In addition, a parallel ANN-algorithm using output-only acceleration responses is newly designed for damage detection in real time. The cross-covariance of two acceleration-signals measured at two different locations is selected as the feature representing the structural condition. Neural networks are trained for potential loading patterns and damage scenarios of the target structure for which its actual loadings are unknown. The feasibility of the proposed method is evaluated from numerical model tests on PSC beams for which accelerations were acquired before and after several damage cases.
A Damage Prognosis Method of Girder Structures Based on Wavelet Neural Networks
Rumian Zhong
2014-01-01
Full Text Available Based on the basic theory of wavelet neural networks and finite element model updating method, a basic framework of damage prognosis method is proposed in this paper. Firstly, a damaged I-steel beam model testing is used to verify the feasibility and effectiveness of the proposed damage prognosis method. The results show that the predicted results of the damage prognosis method and the measured results are very well consistent, and the maximum error is less than 5%. Furthermore, Xinyihe Bridge in the Beijing-Shanghai Highway is selected as the engineering background, and the damage prognosis is conducted based on the data from the structural health monitoring system. The results show that the traffic volume will increase and seasonal differences will decrease in the next year and a half. The displacement has a slight increase and seasonal characters in the critical section of mid span, but the strain will increase distinctly. The analysis results indicate that the proposed method can be applied to the damage prognosis of girder bridge structures and has the potential for the bridge health monitoring and safety prognosis.
Cardboard Boxes: Learning Concepts Galore!
Warner, Laverne; Wilmoth, Linda
2007-01-01
Mrs. Keenan, a preschool teacher, observed her 3-year-old granddaughter Riley pull, tug, and stack piles of holiday boxes on the floor. She remembered that her child care director had suggested using boxes as a curriculum theme, but she hadn't given much thought about the idea until now. She said to herself, "I wonder if my children would be as…
Students' approaches to mathematical tasks using software as a black-box, glass-box or open-box
Hosein, Anesa
2009-01-01
Three mathematical software modes are investigated in this thesis: black-box software showing no mathematical steps; glass-box software showing the intermediate mathematical steps; and open-box software showing and allowing interaction at the intermediate mathematical steps. The glass-box and open-box software modes are often recommended over the black-box software to help understanding but there is limited research comparing all three. This research investigated students' performance and the...
Method of positioning channel box
Upon measuring the dimension of a channel box by disposing ultrasonic sensors to the uppermost portion of a measuring device main body, the deviation of the channel box from the center of the device main body is detected by measuring the distance betwen the sensors at the uppermost portion of the device main body and the lower end of the channel box for four surfaces simultaneously. The direction and the distance for moving the channel box to the center of the device main body are calculated based on the results to feedback tham for the operation of a fuel exchanger, thereby positioning the channel box upon insertion to the device main body. That is, a fuel assembly loaded with the channel box is gradually brought down being suspended from a crane and the position of the channel box is recognized by the ultrasonic sensors, thereafter, the position of the center is corrected and it is brought down again and the outer dimension is measured. Accurate positioning in a short periodof time is enabled and operator's burden can be mitigated to prevent the danger of indury. (N.H.)
Microclimate boxes for panel paintings
Wadum, Jørgen
The use of microclimate boxes to protect vulnerable panel paintings is, therefore, not a new phenomenon of the past two or three decades. Rather, it has been a concern for conservators and curators to protect these objects of art at home and in transit since the end of the nineteenth century. The...... increased number of travelling exhibitions in recent years has heightened the need to protect paintings during circulation (Thomson 1961; Mecklenburg 1991). The use and design of microclimate boxes have been evolving since 1892. These boxes may be divided into three broad groups: those using an active...
Phattrawan Tongkumchum
2005-01-01
In this paper we propose a two-dimensional box plot, a simple bivariate extension of the box plot and the scatter plot. This plot comprises a pair of trapeziums oriented in the direction of a fitted straight line, with symbols denoting extreme values. The choice for the fitted straight resistant line showing the relationship between the two variables is Tukey’s resistance line. The main components of the plot are an inner box containing 50% of the projection points of the observations on the ...
Škaloud, Miroslav; Zörnerová, Marie
Singapore : Research publishing services, 2009 - (Lam, D.), s. 166-171 ISBN 978-981-08-3068-7. [Steel concrete composite and hybrid structures. Leeds (GB), 08.07.2009-10.07.2009] R&D Projects: GA ČR(CZ) GA103/06/0064; GA AV ČR(CZ) IAA200710603 Grant ostatní: GA ČR(CZ) GA103/08/0275; GA ČR(CZ) GA103/08/1677 Institutional research plan: CEZ:AV0Z20710524 Keywords : economic-fabrication steel girders * buckling * fatigue Subject RIV: JM - Building Engineering
GPR signal analysis of post-tensioned prestressed concrete girder defects
The accurate inspection of the duct condition in post-tensioned prestressed concrete (PPC) is an essential part of GPR concrete inspection. The purpose is to inspect the grouting condition of the ducts where the strands are located, to find out if there is a void in the ducts, and if any water exists. In order to investigate the radar image characteristics of different PPC duct defects, a number of model girders were manufactured. Three major ducts are included in our study: (1) well grouted and no void (normal condition); (2) the duct is half filled, and the void is filled by water or air; and (3) the duct is not filled at all, and the duct is water or air filled. The data corresponding to seven different situations are acquired and processed. It is found that the radar can detect the first interface in the duct, and the detailed structure inside the duct cannot be ‘seen’ from the images directly. Characteristic curves greatly help the interpretation. A completely void duct is the easiest to differentiate from the others. The signature for this situation is characterized by a strong and clear reflection interface which becomes weaker as the void is water filled. The normal condition shows the weakest reflection interface. As for the half void situation, the front scan shows a similar result to the normal condition whether it is water or air filled, and the back scan shows similar features to the completely void situation. The experiment and analysis is helpful and instructive for practical engineering inspection. (paper)
Gould, W J; Georgi, M E
1991-10-15
Two eastern box turtles (Terrapene carolina carolina) were treated for myiasis caused by Sarcophaga cistudinis. The tortoises were examined because of swellings of the proximal cervical regions. Both fully recovered following surgical removal of multiple larvae. PMID:1748614
佛陈大桥(扩建)连续钢箱梁设计%Design of Continuous Steel-box Girder in Fochen Extension Bridge
郑楷柱; 何海; 梁立农; 饶瑞
2015-01-01
变截面连续钢箱梁在国内应用方兴未艾,对其研究和成熟工程案例相对较少.本文从佛陈大桥(扩建)连续钢箱梁的结构、防腐、铺装、架设等方面进行深入研究并精心设计,使其很好地结合了桥位所处的环境,满足了施工工期的要求.
箱梁极限承载力破坏仿真分析%Simulation Analysis of Failure of Box Girder Under Ultimate Bearing Capacity
尹冠生; 刘晓伟; 张小慧
2013-01-01
以J-H-C作为混凝土材料模型,以PLASTIC-KINEMATIC作为钢筋材料模型,用数值模拟箱梁在极限承载力下的破坏.实践证明,这两种材料模型能够较好地模拟箱梁在极限承载力下的破坏.
Optimal Design for UHPC Continuous Box Girder Bridge with 400 m Main Span%主跨400 m的UHPC连续梁桥优化设计
刘勇; 邵旭东; 詹豪
2014-01-01
利用超高性能混凝土(UHPC)的优越性能,提出了与之相适应的新型箱梁结构,目的是利用材料的高强度及新结构的轻型化,解决常规混凝土连续箱梁桥易开裂、下挠和自重过大、跨径难以突破300 m的难题.在原有工作的基础上,对主跨400m的UHPC连续箱梁桥进行了整体性能分析及优化设计,优化内容包括桥梁边跨长度、梁高、板厚等主要参数,以得到其合适的取值范围,根据优化结果建议:边跨与主跨跨径比范围为0.55 ～0.65;中支点梁高与主跨跨径比范围为1/20 ～ 1/25;跨中梁高与支点梁高比范围为1/1.8～1/2.3.整体性能分析结果表明:运用UHPC及新结构,能轻松实现连续梁桥400 m跨径的突破,并具有较大的整体刚度及安全储备.综合考虑长期社会经济效益,在主跨跨径300 ～ 500 m范围内,该新型结构可与斜拉桥、悬索桥等其他桥型形成强有力的竞争选型方案.
福州市螺洲大桥主桥钢箱梁顶推施工技术%Fuzhou Beaufort Bridge Pushing steel box girder construction technology
黄强
2011-01-01
Bridge project with Fuzhou Beaufort introduced Pushing walker pan features and construction techniques of process equipment,and the use of centralized control system.At the same time according to the actual situation of this project,analysis of the top platform and push the design of temporary buttress will not rationality and economy.%结合福州市螺洲大桥工程介绍步履式平移顶推施工技术的特点和工艺设备,以及采用的集中控制系统。同时根据本工程实际情况,分析顶推平台与临时支墩的布置与设计的合理性以及经济性。
Lipeng An
2016-07-01
Full Text Available To systematically study the vehicle–bridge coupled dynamic response and its change rule with different parameters, a vehicle model with seven degrees of freedom was built and the total potential energy of vehicle space vibration system was deduced. Considering the stimulation of road roughness, the dynamic response equation of vehicle–bridge coupled system was established in accordance with the elastic system principle of total potential energy with stationary value and the “set-in-right-position” rule. On the basis of the self-compiled Fortran program and bridge engineering, the dynamic response of long-span continuous girder bridge under vehicle load was studied. This study also included the calculation of vehicle impact coefficient, evaluation of vibration comfort, and analysis of dynamic response parameters. Results show the impact coefficient changes with lane number and is larger than the value calculated by the “general code for design of highway bridges and culverts (China”. The Dieckmann index of bridge vibration is also related to lane number, and the vibration comfort evaluation is good in normal conditions. The relevant conclusions from parametric analyses have practical significance to dynamic design and daily operation of long-span continuous girder bridges in expressways. Safety and comfort are expected to improve significantly with further control of the vibration of vehicle–bridge system.
The World Nuclear Transport Institute was formed to fill a need to provide a dedicated vehicle for the radioactive transport and packaging industry sectors worldwide, to exchange information and ideas, all with a view to working toward consolidated industry positions on the key issues affecting safe, efficient and reliable transport. WNTI was also intended to be a strong voice for industry in those international and national bodies where deliberations on such transport safety issues take place. The very fact that companies, sometimes in competition with each other, were prepared to come together in this way, reflects two important points: firstly, it represents an acknowledgement on industry's part that safe, effective and reliable transport is the sine qua non, the absolute essential. And second, it is a recognition that it is enhanced to the extent that industry is able to collaborate to this end. This is thinking outside the box. Another important attribute of safety is 'stability'. Everyone likes to know where he or she stands. The radioactive materials packaging and transport industry thrives within a stable regulatory framework for safety. For a stable regulatory regime allows operators to be properly trained; it allows operators to become familiar with safety requirements, and to be at ease with them. Stability is conducive to safety and efficiency. Stability is good for business too - for stability in package and transport requirements allows sufficient time for a fair return on investment in expensive package design, manufacture, licensing and use over time. Stability should not, however, be opposed to creativity. From experience we can develop new thinking to improve efficiency as illustrated in examples of work related to the packaging and transport of Uranium Concentrates for instance.. Another example is work within WNTI on the thermal test requirements for the packaging of uranium hexafluoride. The robustness of packages is based on the risk factors
Comparison of black-box, glass-box and open-box software for aiding conceptual understanding
Hosein, Anesa; Aczel, James; Clow, Doug; Richardson, John T. E.
2008-01-01
Three mathematical software types: black-box (no steps shown), glass-box (steps shown) and open-box (interactive steps) were used by 32 students to solve conceptual and procedural tasks on the computer via remote observation. Comparison of the three software types suggests that there is no difference in the scores that students receive for conceptual understanding tasks. Students using the black-box are more likely to explore answers than students using the glass and open-box software.
Plate forming and break down pizza box
Pantisano, Frank; Devine, Scott M.
1992-01-01
A standard corrugated paper pizza box is provided with slit cuts cut through the top panel of the pizza box in a shape to form four circular serving plates with a beveled raised edge and cross slit cuts through the bottom panel of the pizza box separating the box into four essentially equal portions for easy disposal.
GS Department
2010-01-01
With a view to ensuring optimum use of the first-aid boxes on the CERN site, we should like to remind you of various changes introduced in March 2009: The TSO of the buildings concerned is responsible for the first-aid boxes, including checking their contents. First-aid boxes may be restocked ONLY at the CERN stores (SCEM No. 54.99.80). This is no longer possible at the Infirmary. The associated cost is charged to the Departments. First-aid boxes should be used only for mild injuries. All other cases should be referred to the Medical Service Infirmary (Bldg. 57 – ground-floor, tel. 73802) between 8.00 a.m. and 5.30 p.m. or to the Fire and Rescue Service (tel. 74444). N.B.: This information does not apply to the red emergency first-aid boxes in the underground areas or to the emergency kits for use in the event of being splashed with hydrofluoric acid.
Asymptotic Symmetries from finite boxes
Andrade, Tomas
2015-01-01
It is natural to regulate an infinite-sized system by imposing a boundary condition at finite distance, placing the system in a "box." This breaks symmetries, though the breaking is small when the box is large. One should thus be able to obtain the asymptotic symmetries of the infinite system by studying regulated systems. We provide concrete examples in the context of Einstein-Hilbert gravity (with negative or zero cosmological constant) by showing in 4 or more dimensions how the Anti-de Sitter and Poincar\\'e asymptotic symmetries can be extracted from gravity in a spherical box with Dirichlet boundary conditions. In 2+1 dimensions we obtain the full double-Virasoro algebra of asymptotic symmetries for AdS$_3$ and, correspondingly, the full Bondi-Metzner-Sachs (BMS) algebra for asymptotically flat space. In higher dimensions, a related approach may continue to be useful for constructing a good asymptotically flat phase space with BMS asymptotic symmetries.
Asymptotic symmetries from finite boxes
Andrade, Tomás; Marolf, Donald
2016-01-01
It is natural to regulate an infinite-sized system by imposing a boundary condition at finite distance, placing the system in a 'box.' This breaks symmetries, though the breaking is small when the box is large. One should thus be able to obtain the asymptotic symmetries of the infinite system by studying regulated systems. We provide concrete examples in the context of Einstein-Hilbert gravity (with negative or zero cosmological constant) by showing in 4 or more dimensions how the anti-de Sitter and Poincaré asymptotic symmetries can be extracted from gravity in a spherical box with Dirichlet boundary conditions. In 2 + 1 dimensions we obtain the full double-Virasoro algebra of asymptotic symmetries for AdS3 and, correspondingly, the full Bondi-Metzner-Sachs (BMS) algebra for asymptotically flat space. In higher dimensions, a related approach may continue to be useful for constructing a good asymptotically flat phase space with BMS asymptotic symmetries.
Identifying competencies of boxing coaches
Ioannis Tasiopoulos
2014-10-01
Full Text Available The purpose of this study was to find out the management skills required by boxing coaches to administrate their clubs. For the purposes of this study a scale was constructed which was answered by 98 boxing coaches. Explanatory factor analysis revealed seven factors: Communication-public relations (5 items, event management (4 items, management techniques (4 items, new technologies (4 items, prevention-safety (2 items, sport (5 items and sports facilities (2 items. The Cronbach of the scale was 0.85. The five competencies that rated by the coaches were: Supervisors of the area of training, maintaining excellent communication with athletes, using new technologies (e-mail, internet, handling disciplinary matters, accidents, complaints and reports on some sporting games and promoted harmony among athletes. We concluded that boxing coaches understand that the competencies required for meeting their obligations, were related to sports, prevention, safety and communications-public relations.
Innovations in Los Alamos alpha box design
Destructive examinations of irradiated fuel pins containing plutonium fuel must be performed in shielded hot cells with strict provisions for containing the plutonium. Alpha boxes provide containment for the plutonium, toxic fission products, and other hazardous highly radioactive materials. The alpha box contains windows for viewing and a variety of transfer systems specially designed to allow transfers in and out of the alpha box without spread of the hazardous materials that are contained in the box. Alpha boxes have been in use in the Wing 9 hot cells at Los Alamos National Laboratory for more than 20 years. Features of the newly designed alpha boxes are presented
Innovations in Los Alamos alpha box design
Ledbetter, J.M.; Dowler, K.E.; Cook, J.H.
1985-01-01
Destructive examinations of irradiated fuel pins containing plutonium fuel must be performed in shielded hot cells with strict provisions for containing the plutonium. Alpha boxes provide containment for the plutonium, toxic fission products, and other hazardous highly radioactive materials. The alpha box contains windows for viewing and a variety of transfer systems specially designed to allow transfers in and out of the alpha box without spread of the hazardous materials that are contained in the box. Alpha boxes have been in use in the Wing 9 hot cells at Los Alamos National Laboratory for more than 20 years. Features of the newly designed alpha boxes are presented.
Calculation of parton distributions in the 'cavity approximation' to the MIT bag model gives a divergent sum of positive terms. In this version of the model the flexible movable bag is replaced by an inflexible immovable box. This suggests that Bjorken scaling does not hold for the deep inelastic scattering in this version of the model. (K.A.)
On the Dirichlet's Box Principle
Poon, Kin-Keung; Shiu, Wai-Chee
2008-01-01
In this note, we will focus on several applications on the Dirichlet's box principle in Discrete Mathematics lesson and number theory lesson. In addition, the main result is an innovative game on a triangular board developed by the authors. The game has been used in teaching and learning mathematics in Discrete Mathematics and some high schools in…
崔增印
2008-01-01
The story goes that some time ago,a man pun- ished his 3-year-old daughter for wasting a roll of gold wrapping paper.Money was tight and he became infuriated when the child tried to decorate a box to put under the Christmas tree.Nevertheless,the little girl brought the gift to
Škaloud, Miroslav; Zörnerová, Marie
Brno : Akademické nakladatelství CERN, s.r.o. 2009, 2009 - (Melcher, J.; Skyva, J.; Karmazínová, M.), s. 293-302 ISBN 978-80-7204-635-5. [Ocelové konstrukce a mosty 2009. Brno (CZ), 23.09.2009-25.09.2009] R&D Projects: GA ČR(CZ) GA103/09/0091 Grant ostatní: GA ČR(CZ) GA103/08/0275; GA ČR(CZ) GA103/08/1677 Institutional research plan: CEZ:AV0Z20710524 Keywords : thin-walled steel girders * buckling * S-N curves Subject RIV: JM - Building Engineering
Andersen, Ingrid Marie Vincent; Jensen, Jørgen Juncher
2012-01-01
the ship. The theory takes into account non-linear radiation forces (memory effects) through the use of a set of higher order differential equations. The non-linear hydrostatic restoring forces and non-linear Froude-Krylov forces are determined accurately at the instantaneous position of the ship in...... global hull girder loads as consequence of the increased hull flexibility must be considered. This is especially so as the rules of the classification societies do not explicitly account for the effect of hull flexibility on the global loads. In the present paper an analysis has been carried out for the...... 9,400 TEU container ship used as case-ship in the EU project TULCS (Tools for Ultra Large Container Ships). A non-linear time-domain strip theory is used for the hydrodynamic analysis of the vertical bending moment amidships in sagging and hogging conditions for a flexible and a rigid modelling of...
Taniguchi, N.; Yoda, T. [Waseda University, Tokyo (Japan). School of Science and Engineering
1997-10-15
An evaluation is being established on composite girders with corrugated steel webs that they are a composite girder having excellent mechanical characteristics. However, structural analysis of these composite girders is not easy even of the one-dimensional analysis. Therefore, a proposal was made on a simple method for bending analysis of a composite girder with corrugated webs having I-section subjected to bending. The result of the analysis using the proposed method was compared with measured values, and the reasonability of the test was investigated including that for the non-linear region. In this analysis, the I-section girder was converted equivalently into a multi-layered beam consisting of cross sections with an equivalent width, and displacement and stress in each layer were approximated linearly by dividing the multi-layered beam into fine layers of `N` number. Formulation was performed by using an ordinary matrix method based on the derived displacement field and stress field. An initial stress method was used for non-linearity analysis of the beams. This analysis was found effective in analyzing a beam subjected to strong effect of shear as in a corrugated steel web composite girder. Among the results of the linearity analyses, the displacement and stress agreed nearly well with the measured values. The non-linearity analysis was performed simply when combined with the initial stress method. 16 refs., 24 figs., 4 tabs.
Cosmetic Foot Surgery: Fashion's Pandora's Box
... News, Videos & Podcasts » Articles » Text Size Print Bookmark Cosmetic Foot Surgery: Fashion’s Pandora’s Box? Cosmetic Foot Surgery: Fashion’s Pandora’s Box? Foot and Ankle Surgeons Warn ...
The Heuristic Interpretation of Box Plots
Lem, Stephanie; Onghena, Patrick; Verschaffel, Lieven; Van Dooren, Wim
2013-01-01
Box plots are frequently used, but are often misinterpreted by students. Especially the area of the box in box plots is often misinterpreted as representing number or proportion of observations, while it actually represents their density. In a first study, reaction time evidence was used to test whether heuristic reasoning underlies this…
Box-shaped halophilic bacteria.
Javor, B; Requadt, C; Stoeckenius, W
1982-01-01
Three morphologically similar strains of halophilic, box-shaped procaryotes have been isolated from brines collected in the Sinai, Baja California (Mexico), and southern California (United States). Although the isolates in their morphology resemble Walsby's square bacteria, which are a dominant morphological type in the Red Sea and Baja California brines, they are probably not identical to them. The cells show the general characteristics of extreme halophiles and archaebacteria. They contain ...
Sindbæk, Søren Michael
2013-01-01
Long-distance communication has emerged as a particular focus for archaeological exploration using network theory, analysis, and modelling. Initial attempts to adapt methods from social network analysis to archaeological data have, however, struggled to produce decisive results. This paper argues...... ruined network from observable distributions and patterns of association in the archaeological record. In formal terms this is not a problem of network analysis, but network synthesis: the classic problem of cracking codes or reconstructing black-box circuits....
Elser, Stefan
2011-01-01
Ziel dieser Doktorarbeit ist es, bekannte und oft verwendete Eigenschaften des Tychonow-Produkts in analoger Form für das k-Box-Produkt zu beweisen, was bisher noch nicht geschehen ist, und die Verbindung zwischen der Infinitären Kombinatorik und der Topologie zu vertiefen. In der Infinitären Kombinatorik, ein Zweig der modernen Mengenlehre, bedient man sich gerne topologischer Begriffe, um einerseits Ergebnisse zu verdeutlichen und um andererseits den sehr abstrakten kombinatorischen Be...
Study of Shear Stud Connector Layout for Composite Girders%结合梁剪力钉布置形式研究
侯健; 罗扣
2014-01-01
为提高结合梁桥桥面板的整体性，并方便施工，对剪力钉集束式（在钢梁腹板的上翼缘每隔一定距离布置1束剪力钉群，各钉群之间留有相应宽度无钉区）布置形式进行研究。通过建立结合梁结构的有限元模型，分别计算恒载、车辆偏载作用下，集束式和均布式（钢梁上翼缘均匀、等间距的剪力钉布置形式）桥面板和剪力钉的滑移量、钢梁的应力、钢梁底板位移等。研究结果表明：剪力钉集束式布置具有桥面板整体性好，施工工序简单等特点；在荷载作用下，剪力钉采用集束式布置能够保证钢梁和混凝土桥面板之间有效传力；汽车偏载作用下，集束式布置也可以保证钢梁与混凝土桥面板之间的有效结合，不会发生桥面板上掀现象。%In order to improve the integrity of the deck of composite girder bridge and for the convenience of construction ,the clustered shear stud connectors arrangement was studied (in the upper flange of the webs of the steel girder ,clusters of shear stud connectors are installed with e-qual intervals and a connector-free zone with certain width among the clusters is reserved ) .The fi-nite element model of the composite girder structure was established to calculate respectively the slip amount of the bridge deck and shear stud connectors ,stress in the steel girder and the dis-placement of the steel girder base plate under the action of dead load and eccentric vehicle load ,for both the clustered arrangement and uniform arrangement (the shear stud connectors are uniformly arranged in the upper flange of the steel girder with equal intervals ) .The results of the study dem-onstrate that the clustered arrangement of shear stud connectors is favorable for the integrity of the bridge deck and simplifies the construction procedures ;under the action of loads ,the clustered ar-rangement of shear stud connectors allows the effective force
王存贵; 王殿永; 高杰; 靳春尚
2012-01-01
The main bridge of Fenfangwan Changjiang River Bridge in Chongqing City is a semi-floating system steel truss girder cable-stayed bridge with double pylons, double cable planes and with span arrangement (216. 5 + 464 + 216. 5) m. The main girder of the bridge is designed as the steel truss girder structure erected by the piece-by-piece assembling. In the light of the topographic conditions of the south and north banks, the asymmetric way of erection was chosen for the girder. The steel truss girder on the south bank side was erected from the side span towards the central span. The girder of the side span was assembled on the scaffolding, the girder in the middle was erected first and then the components like the edge stringers and edge deck plates were erected, using the deck truck cranes. The girder for the main span was erected by the cantilever assembling method. The girder of the north bank was erected by the balanced two-cantilever assembling method and the 5 blocks of the girder atop and on both sides of a main pier were assembled on the pier-side brackets.%重庆粉房湾长江大桥主桥为跨度(216.5+464+216.5)m的双塔双索面半飘浮体系钢桁梁斜拉桥,主梁采用钢桁梁结构.钢桁梁采取散拼架设,南、北岸钢桁梁根据地形情况选取了不对称的方式施工.南岸钢桁梁由边跨向中跨架设,边跨钢桁梁采用支架拼装,先架设中间桁架,再利用桥面汽车吊架设边纵梁、边桥面板等构件；主跨钢桁梁采用悬臂拼装.北岸钢桁梁采用双悬臂对称架设,主墩墩顶及两侧共5个节段钢桁梁采用墩旁托架拼装.
Ionization box type radiation detector
An ionization box for monitoring radiation rays, a first amplification circuit of a multi-stage amplification circuit employing a MOS type FET as an initial stage amplification device, a second amplification circuit employing a junction type FET as an initial stage amplification device, a first change-over switch for switching ionization current depending on input signals, a second change-over switch for switching output signals, and a signal level discrimination circuit are constituted integrally. When radiation dose rate is low, the ionization current is inputted to the first amplification circuit and outputted as a radiation ray monitor signal and, when the radiation dose rate is increased to higher than a predetermined value, the ionization current is inputted to the second amplification circuit and outputted as a radiation ray monitor signal. That is, monitoring accuracy is high when the ionization current is low since the MOS type FET of high input impedance is used. If the ionization current is higher than a predetermined value, there is no worry that the detection becomes impossible since the junction type FET having less worry of causing characteristic change due to high radiation dose rate is used. Accordingly, ionization box type monitor at a high monitoring reliability can be obtained. (N.H.)
F-box proteins in flowering plants
无
2002-01-01
In eukaryotes, the ubiquitin-mediated protein degradation pathway has been shown to control several key biological processes such as cell division, development, metabolism and immune response. F-box proteins, as a part of SCF (Skp1-Cullin (or Cdc53)-F-box) complex, functioned by interacting with substrate proteins, leading to their subsequent degradation by the 26S proteasome. To date, several F-box proteins identified in Arabidopsis and Antirrhinum have been shown to play important roles in auxin signal transduction, floral organ formation, flowering and leaf senescence. Arabidopsis genome sequence analysis revealed that it encodes over 1000 predicted F-box proteins accounting for about 5% of total predicted proteins. These results indicate that the ubiquitin-mediated protein degradation involving the F-box proteins is an important mechanism controlling plant gene expression. Here, we review the known F-box proteins and their functionsin flowering plants.
Understanding Recommender Dynamics driving Box Office Revenues
Yeung, C H; Jin, C -H
2010-01-01
We introduce a simple model to investigate the underlying dynamics driving movie box office. Without an explicit reliance on time, the box office of movies evolves naturally by movie-movie competition through reviews listed on a centralized recommender system. A simple mean-field approximation is employed which assumes an average interaction between the competing movies, and describes the interesting box office dynamics. Box office hits are found for movies with quality beyond a critical value, leading to booms in gross box office. Such critical value is dependent on the reviewing behaviors, intention of movie goers for new movies, and the quality of the peer competing movies. Finally we compare our analytical results with simulations and real system and obtain qualitative agreements, suggesting the present model in describing the fundamental dynamics of box office.
Metod of black box and their us
Novotný, Martin
2013-01-01
This thesis on a topic "black-box method and its use" deals with the description of the method of solving problematic tasks as a black box and its use in teaching. Using the theory of systems and cybernetics disciplines, especially cybernetic-pedagogy attempts to describe this method so that it is as efficient as possible and to maximize the benefits for students. Besides, the implementation of selected black box that will be suitable and used for teaching subjects electrotechnics, automatiza...
Repackaging SRS Black Box TRU Waste
Historically, large items of TRU Waste, which were too large to be packaged in drums for disposal have been packaged in various sizes of custom made plywood boxes at the Savannah River Site (SRS), for many years. These boxes were subsequently packaged into large steel ''Black Boxes'' for storage at SRS, pending availability of Characterization and Certification capability, to facilitate disposal of larger items of TRU Waste. There are approximately 107 Black Boxes in inventory at SRS, each measuring some 18' x 12' x 7', and weighing up to 45,000 lbs. These Black Boxes have been stored since the early 1980s. The project to repackage this waste into Standard Large Boxes (SLBs), Standard Waste Boxes (SWB) and Ten Drum Overpacks (TDOP), for subsequent characterization and WIPP disposal, commenced in FY04. To date, 10 Black Boxes have been repackaged, resulting in 40 SLB-2's, and 37 B25 overpack boxes, these B25's will be overpacked in SLB-2's prior to shipping to WIPP. This paper will describe experience to date from this project
Interchangeable breech lock for glove boxes
Lemonds, David Preston
2015-11-24
A breech lock for a glove box is provided that may be used to transfer one or more items into the glove box. The breech lock can be interchangeably installed in place of a plug, glove, or other device in a port or opening of a glove box. Features are provided to aid the removal of items from the breech lock by a gloved operator. The breech lock can be reused or, if needed, can be replaced with a plug, glove, or other device at the port or opening of the glove box.
Model Equations: "Black Box" Reconstruction
Bezruchko, Boris P.; Smirnov, Dmitry A.
Black box reconstruction is both the most difficult and the most tempting modelling problem when any prior information about an appropriate model structure is lacking. An intriguing thing is that a model capable of reproducing an observed behaviour or predicting further evolution should be obtained only from an observed time series, i.e. "from nothing" at first sight. Chances for a success are not large. Even more so, a "good" model would become a valuable tool to characterise an object and understand its dynamics. Lack of prior information causes one to utilise universal model structures, e.g. artificial neural networks, radial basis functions and algebraic polynomials are included in the right-hand sides of dynamical model equations. Such models are often multi-dimensional and involve quite many free parameters.
Unification of box shapes in molecular simulations
Bekker, H.
1997-01-01
In molecular simulations with periodic boundary conditions the computational box may have five different shapes: triclinic; the hexagonal prism; two types of dodecahedrons; and the truncated octahedron. In this article, we show that every molecular simulation, formulated in one of these boxes, can b
Black-Box Search by Unbiased Variation
Lehre, Per Kristian; Witt, Carsten
2012-01-01
The complexity theory for black-box algorithms, introduced by Droste, Jansen, and Wegener (Theory Comput. Syst. 39:525–544, 2006), describes common limits on the efficiency of a broad class of randomised search heuristics. There is an obvious trade-off between the generality of the black-box model...
Cosmetic Foot Surgery: Fashion's Pandora's Box
... Fashion’s Pandora’s Box? A A A | Print | Share Cosmetic Foot Surgery: Fashion’s Pandora’s Box? Foot and ankle ... extreme and imprudent as it may sound, the cosmetic surgery craze isn't just for faces anymore- ...
Modern biotechnology Panacea or new Pandora's box?
Tramper, J.; Yang Zhu, Yang
2011-01-01
According to Greek mythology Pandora was sent down to earth upon the orders of Zeus. She was given a mysterious box which she was not allowed to open. However, Pandora was very curious and when she arrived on earth she couldn?t help taking a peek inside the box. She saw that it was filled with gifts
Box Plots in the Australian Curriculum
Watson, Jane M.
2012-01-01
This article compares the definition of "box plot" as used in the "Australian Curriculum: Mathematics" with other definitions used in the education community; describes the difficulties students experience when dealing with box plots; and discusses the elaboration that is necessary to enable teachers to develop the knowledge necessary to use them…
49 CFR 178.515 - Standards for reconstituted wood boxes.
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for reconstituted wood boxes. 178.515... wood boxes. (a) The identification code for a reconstituted wood box is 4F. (b) Construction requirements for reconstituted wood boxes are as follows: (1) The walls of boxes must be made of...
Spatial Effect on Railway Trough Girder with Reactive Powder Concrete%铁路活性粉末混凝土槽形梁的空间作用效应
李志光; 余自若; 王月
2013-01-01
The authors carried out three-dimensional finite element analysis on a 32 m railway trough girder which was made of reactive powder concrete.After working out shear lag coefficients under different load conditions,the rule of shear lag was analyzed,and the results indicated that the shear lag effect in this reactive powder concrete trough girder was larger than that of common concrete girder.Further,the spatial effect on transversal and longitudinal bending moments was analyzed,and the study result on the influence lines of transversal bending moments indicated that,due to the spatial effect,any force on any point of the trough girder would cause transversal bending moment which should not be ignored.Finally,the study result on influence lines of longitudinal bending moments showed that,there was spatial effect on equivalent load in reactive powder concrete trough girder; the closer to the girder end the place was,the more obviously the effect became,which also should not be ignored.Therefore,in the design of this kind of railway girder,the spatial effect on the vicinity of girder end should be taken seriously.%对32 m铁路活性粉末混凝土槽形梁进行三维有限元分析,计算出不同工况下的剪力滞系数,并对剪力滞规律进行分析,研究表明该梁的剪力滞效应较普通混凝土梁更加明显;对其横向和纵向弯矩的空间效应进行分析,对横向弯矩影响线的研究表明,受空间作用的影响,梁上任意一点受力均会在某一截面产生不可忽略的横向弯矩;对纵向弯矩影响线的研究表明空间作用对活性粉末混凝土槽形梁换算荷载的影响在越靠近端部影响越明显,且该影响不可忽略,所以在设计该种梁时需要在靠近端部位置充分考虑空间作用的影响.
Improvements relating to glove boxes
It is stated that radiation problems with glove boxes can only be partly overcome by adding shielding to their working faces, since about 25% of the working face may be taken up with glove ports at which the only shielding provided is that of the glove. A glove port cover is here described, mountable above the port, comprising a number of flaps of lead-loaded flexible material. The flaps can be pushed aside by hand to permit access to a glove fixed in the port, but overlap to close off the port when the hand is withdrawn. The lead loaded flexible material preferably has a natural or synthetic rubber base. Constructional details are given. Only the flaps need to be lead-loaded, and to facilitate manufacture and handling the surfaces of the cover are preferably lead-free. Three flaps can suffice, but five or six are preferred. For mounting purposes a cover may have beading at its periphery for clamped location in a groove round the glove port. (U.K.)
殷红
2013-01-01
The main bridge of Huanggang Changjiang River Rail-cum-Road Bridge is a steel truss girder cable-stayed bridge with double pylons and double cable planes.The chord and web members of the main truss of the bridge were designed as the ones of parallelogram sections.To guarantee the manufacturing quality of the members,the key techniques for the manufacturing were studied.The precision of the geometric dimensions of the members was guaranteed by the techniques of controlling the precision of the inclined angle grooves of the welded edges,fine adjusting the diagonal line dimensions of the diaphragms (controlling the angles of the end openings) and assembling the members on the special jig supports.The precision of the anchor tube positioning was guaranteed by the techniques of converting the spatial positioning dimensions of the anchor tubes into the plane positioning dimensions and controlling the installing,welding procedures of the anchor boxes and the installing precision of the anchor tubes.The assembling quality of the steel truss girder was guaranteed by the techniques of testing the precision of the hole groups at the inclined web member joints by the special testing templates for the web member joints.Practice proves that the key techniques applied to the manufacturing of the members effectively tackle the control problems of the members of parallelogram sections and guarantee the manufacturing precision of the steel truss girder of the bridge.%黄冈公铁两用长江大桥主桥为双塔双索面钢桁梁斜拉桥,其主桁弦杆和腹杆采用平行四边形截面.为保证主桁平行四边形截面杆件的制造质量,对其制造关键技术进行研究.通过控制杆件焊接边斜角坡口精度、微调隔板对角线尺寸(控制端口角度)、应用专用胎架组拼杆件的技术保证杆件形位尺寸的精度.通过将锚管空间定位尺寸转化为平面定位尺寸、控制锚箱安装及焊接工序、控制锚管安装精度的技术
Design of the Main Bridge Steel Truss Girder of Xinglong Bridge%兴隆大桥主桥钢桁梁设计
杨文; 何耀炜
2016-01-01
下承式钢桁梁桥因其具有建筑高度低、施工速度快和结构轻巧简洁等优点，成为中等跨度公路桥梁中有竞争力的桥型。文中以兴隆大桥为依托，建立数学分析模型，对下承式钢桁梁桥结构的受力特性进行分析，并指出该类型桥梁施工的方法和技术要点。%The through steel truss girder bridge becomes a bridge type for medium span highway bridg-es with low building height,fast construction speed and the advantages of compact and simple struc-ture.Based on the Xinglong Bridge,a mathematical analysis model is established in this paper to ana-lyze the mechanical characteristics of the steel truss girder bridge,and the method and technical points of the bridge construction are pointed out.
Skopenkov, Mikhail
2011-05-01
Given a triangular cake and a box in the shape of its mirror image, how can the cake be cut into a minimal number of pieces so that it can be put into the box? The cake has icing, so we are not allowed to put it into the box upside down. V. G. Boltyansky asked this question in 1977 and showed that three pieces always suffice. In this paper we provide examples of cakes that cannot be cut into two pieces to be put into the box. This shows that three is the answer to Boltyansky\\'s question. We also give examples of cakes which can be cut into two pieces. © THE MATHEMATICAL ASSOCIATION OF AMERICA.
Spacer for supporting fuel element boxes
A spacer plate unit arranged externally on each side and at a predetermined level of a polygonal fuel element box for mutually supporting, with respect to one another, a plurality of the fuel element boxes forming a fuel element bundle, is formed of a first and a second spacer plate part each having the same length and the same width and being constituted of unlike first and second materials, respectively. The first and second spacer plate parts of the several spacer plate units situated at the predetermined level are arranged in an alternating continuous series when viewed in the peripheral direction of the fuel element box, so that any two spacer plate units belonging to face-to-face oriented sides of two adjoining fuel element boxes in the fuel element bundle define interfaces of unlike materials
Mystery Boxes, X Rays, and Radiology.
Thomson, Norman
2000-01-01
Indicates the difficulties of teaching concepts beyond light and color and creating memorable learning experiences. Recommends sequential activities using the mystery box approach to explain how scientists and doctors use photon applications. (YDS)
Skopenkov, Mikhail
2010-01-01
Given a cake in form of a triangle and a box that fits the mirror image of the cake, how to cut the cake into a minimal number of pieces so that it can be put into the box? The cake has an icing, so that we are not allowed to put it into the box upside down. V.G. Boltyansky asked this question in 1977 and showed that three pieces always suffice. In this paper we provide examples of cakes that cannot be cut into two pieces to put into the box. This shows that three is the answer to V.G. Boltyansky's question. Also we give examples of cakes which can be cut into two pieces.
Decommissioning a tritium glove-box facility
Folkers, C.L.; Homann, S.G.; Nicolosi, A.S.; Hanel, S.L.; King, W.C.
1979-08-08
A large glove-box facility for handling reactive metal tritides was decommissioned. Major sections of the glove box were decontaminated and disassembled for reuse at another tritium facility. To achieve the desired results, decontamnation required repeated washing, first with organic liquids, then with water and detergents. Worker protection was provided by simple ventilation combined with careful monitoring of the work areas and employees. Several innovative techniques are described.
Decommissioning a tritium glove-box facility
A large glove-box facility for handling reactive metal tritides was decommissioned. Major sections of the glove box were decontaminated and disassembled for reuse at another tritium facility. To achieve the desired results, decontamnation required repeated washing, first with organic liquids, then with water and detergents. Worker protection was provided by simple ventilation combined with careful monitoring of the work areas and employees. Several innovative techniques are described
SET Backaction on the Single Electron Box
Turek, B. A.; Lehnert, K. W.; Clerk, A.; Gunnarsson, D.; Bladh, K.; Delsing, P.; Schoelkopf, R. J.
2005-01-01
We report an experimental observation of the backaction of a Single Electron Transistor (SET) measuring the Coulomb staircase of a single electron box. As current flows through the SET, the charge state of the SET island fluctuates. These fluctuations capacitively couple to the box and cause changes in the position, width, and asymmetry of the Coulomb staircase. A sequential tunnelling model accurately recreates these effects, confirming this mechanism of the backaction of an SET. This is a f...
Random Young diagrams in a Rectangular Box
Beltoft, Dan; Boutillier, Cédric; Enriquez, Nathanaël
We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape.......We exhibit the limit shape of random Young diagrams having a distribution proportional to the exponential of their area, and confined in a rectangular box. The Ornstein-Uhlenbeck bridge arises from the fluctuations around the limit shape....
HYDROGEN AND VOC RETENTION IN WASTE BOXES
PACE ME; MARUSICH RM
2008-11-21
The Hanford Waste Management Project Master Documented Safety Analysis (MDSA) (HNF-14741, 2003) identifies derived safety controls to prevent or mitigate the risks of a single-container deflagration during operations requiring moving, venting or opening transuranic (TRU)-waste containers. The issue is whether these safety controls are necessary for operations involving TRU-waste boxes that are being retrieved from burial at the Hanford Site. This paper investigates the potential for a deflagration hazard within these boxes and whether safety controls identified for drum deflagration hazards should be applied to operations involving these boxes. The study evaluates the accumulation of hydrogen and VOCs within the waste box and the transport of these gases and vapors out of the waste box. To perform the analysis, there were numerous and major assumptions made regarding the generation rate and the transport pathway dimensions and their number. Since there is little actual data with regards to these assumptions, analyses of three potential configurations were performed to obtain some indication of the bounds of the issue (the concentration of hydrogen or flammable VOCs within a waste box). A brief description of each of the three cases along with the results of the analysis is summarized.
49 CFR 178.517 - Standards for plastic boxes.
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for plastic boxes. 178.517 Section 178... PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.517 Standards for plastic boxes. (a) The following are identification codes for plastic boxes: (1) 4H1 for an expanded plastic box; and (2) 4H2 for...
49 CFR 230.101 - Steam locomotive driving journal boxes.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Steam locomotive driving journal boxes. 230.101... Locomotives and Tenders Running Gear § 230.101 Steam locomotive driving journal boxes. (a) Driving journal boxes. Driving journal boxes shall be maintained in a safe and suitable condition for service. Not...
Effect of an odor eliminator on feline litter box behavior.
Cottam, Nicole; Dodman, Nicholas H
2007-02-01
Decreasing litter box odor may be an important treatment component in addressing feline inappropriate elimination. A three-phase study was conducted to determine if the use of Zero Odor litter box spray increases the preference of litter boxes to cats, presumably by its odor-eliminating quality. In the first phase, cats were given a litter box preference test between a litter box sprayed with Zero Odor and one without. In the second phase, the number of occurrences of behaviors indicative of a cat's dissatisfaction with the litter box (scratching at the sides of the box, floor or wall, hesitating when entering the litter box, balancing on the side of the box and eliminating outside of the litter box) was compared before and after the use of Zero Odor. Last, the frequency of eliminations that occurred outside the litter box was measured during a baseline phase and a test phase, in which Zero Odor was sprayed into all litter boxes in the home. Significantly fewer behaviors associated with feline litter box dissatisfaction and fewer undesirable eliminations were observed in phases 2 and 3, respectively. These findings suggest that use of Zero Odor litter box spray appears to decrease litter box odor and increases the attractiveness of litter box to cats. PMID:17049291
49 CFR 178.514 - Standards for plywood boxes.
2010-10-01
... 49 Transportation 2 2010-10-01 2010-10-01 false Standards for plywood boxes. 178.514 Section 178... PACKAGINGS Non-bulk Performance-Oriented Packaging Standards § 178.514 Standards for plywood boxes. (a) The identification code for a plywood box is 4D. (b) Construction requirements for plywood boxes are as follows:...
Bending analysis of laminated composite box beams
Tripathy, A.K.; Patel, H.J.; Pang, S.S. (Louisiana State Univ., Baton Rouge, LA (United States). Dept. of Mechanical Engineering)
1994-01-01
Box beams are widely used in weight reduction structures such as aircraft wings. The use of composite box beams further reduces the weight factor for such structures with the same deflection and stress as that of isotropic box beams. The difference in the behavior of composite box beam with different fiber orientation, number of plies, and number of stringers also provides a wide range of designing parameters to achieve the required performance for a given problem. A bending analysis has been carried out for the study of deflections and stresses for box beams of different material (isotropic and laminated composites), size, and number of stringers subjected to different kinds of loading conditions. A finite element model has been developed based on the strain energy principle, and the results are compared with an available commercial code COSMOS/M.'' Experiments using aluminum and scotchply composite laminates were conducted to verify the results. An optimal design for size and number of stiffeners for a given loading condition has been achieved. Investigations have also been carried out to find the effect of transverse shear on the span-wise normal stress.
Pharmacy Students’ Knowledge of Black Box Warnings
Shireman, Theresa I.; Generali, Joyce; Rigler, Sally; Mayorga, Angela
2010-01-01
Objective To evaluate the progression of pharmacy students’ knowledge of black box warnings across 3 years of didactic training, and to determine how they stay current with new warnings. Methods A cross-sectional survey instrument was administered to pharmacy students in their first (P1), second (P2), and third (P3) professional years. The survey assessed student awareness of medications possessing a black box warning and familiarity with the warning content for 20 medications (15 with and 5 without warnings). Results Mean number of correct responses identifying the presence or absence of a black box warning among the 20 medications were 5.8 ± 3.3, 9.6 ± 4.0, and 14.8 ± 2.8 for the P1, P2, and P3 students, respectively. Knowledge of black box warning content was variable. Students were least aware of the warning content for stavudine and enoxaparin. Students were most familiar with the warning content for paroxetine and estrogen. Conclusion Students’ awareness and understanding of black box warnings was proportional to their educational progression, but their knowledge level was inconsistent across drug groups. PMID:20221356
Nearly Seamless Vacuum-Insulated Boxes
Stepanian, Christopher J.; Ou, Danny; Hu, Xiangjun
2010-01-01
A design concept, and a fabrication process that would implement the design concept, have been proposed for nearly seamless vacuum-insulated boxes that could be the main structural components of a variety of controlled-temperature containers, including common household refrigerators and insulating containers for shipping foods. In a typical case, a vacuum-insulated box would be shaped like a rectangular parallelepiped conventional refrigerator box having five fully closed sides and a hinged door on the sixth side. Although it is possible to construct the five-closed-side portion of the box as an assembly of five unitary vacuum-insulated panels, it is not desirable to do so because the relatively high thermal conductances of the seams between the panels would contribute significant amounts of heat leakage, relative to the leakage through the panels themselves. In contrast, the proposal would make it possible to reduce heat leakage by constructing the five-closed-side portion of the box plus the stationary portion (if any) of the sixth side as a single, seamless unit; the only remaining seam would be the edge seal around the door. The basic cross-sectional configuration of each side of a vacuum-insulated box according to the proposal would be that of a conventional vacuum-insulated panel: a low-density, porous core material filling a partially evacuated space between face sheets. However, neither the face sheets nor the core would be conventional. The face sheets would be opposite sides of a vacuum bag. The core material would be a flexible polymer-modified silica aerogel of the type described in Silica/Polymer and Silica/Polymer/Fiber Composite Aero - gels (MSC-23736) in this issue of NASA Tech Briefs. As noted in that article, the stiffness of this core material against compression is greater than that of prior aerogels. This is an important advantage because it translates to greater retention of thickness and, hence, of insulation performance when pressure is
Advances in the theory of box integrals
Bailey, David H.; Borwein, J.M.; Crandall, R.E.
2009-06-25
Box integrals - expectations <|{rvec r}|{sup s}> or <|{rvec r}-{rvec q}|{sup s}> over the unit n-cube (or n-box) - have over three decades been occasionally given closed forms for isolated n,s. By employing experimental mathematics together with a new, global analytic strategy, we prove that for n {le} 4 dimensions the box integrals are for any integer s hypergeometrically closed in a sense we clarify herein. For n = 5 dimensions, we show that a single unresolved integral we call K{sub 5} stands in the way of such hyperclosure proofs. We supply a compendium of exemplary closed forms that naturally arise algorithmically from this theory.
谷丹丹; 孙全胜
2015-01-01
为研究M PC复合材料加固空心板梁桥的有效性，在某跨径13 m的空心板梁桥主梁跨中11 m范围内浇筑M PC复合材料进行加固，桥梁加固前与加固后分别进行静载试验，并采用有限元法建立加固前后主梁的有限元模型，分析加固前后主梁的挠度、裂缝和应变的变化。分析结果表明：工况1（跨中最大弯矩横向对称加载）、工况2（跨中最大弯矩横向偏载加载）下主梁加固后的挠度较加固前分别降低了13．4％、12．6％，加固后主梁的挠度明显减小；在试验过程中，加固后主梁裂缝未见明显变化，裂缝区应变水平降低，较好地抑制了原有裂缝的发展；工况1、工况2下主梁加固后的应变较加固前分别降低了13．75％、14．79％，加固后主梁受拉区应变显著降低；加固后校验系数改善率最大为13．89％，该加固方法能够有效地提高桥梁的承载力和刚度。%To study the efficiency of using MPC composite material to strengthen void plate girder bridge ,within the 11 m area of the midspan of the main girder of a 3 × 13 m void plate girder bridge ,the MPC composite material was cast for the strengthening purpose .Static tests were done before and after the strengthening ,and the finite element method was used to establish the models of the main girder before and after the strengthening ,to analyze the variation of main span deflec‐tion ,cracking and strain .The results of the analysis indicate that under two load cases (load case 1 is the transverse symmetrical loading with maximum midspan bending moment and the load case 2 is the transverse eccentric loading with maximum midspan bending moment .) ,the deflection of main girder reduces by 13 .4% and 12 .6% , respectively , compared with the data before the strengthening ,and the deflection of the main girder after strengthening is distinctively declined . During the process of the tests ,the cracking of the main
The primary objective of conducting the full-scale fire tests of the DOT (Department of Transportation) 7A FRP Boxes was to provide information to assist in quantifying the fire hazard of the storage located at the Radioactive Waste Management Complex (RWMC), and to learn if changing the storage array will decrease the fire risk. Also, the level of fire fighting and fire protection required to maintain the risk at the RWMC within acceptable DOE guidelines was investigated. Two full-scale fire tests were conducted at Southwest Research Institute (SwRI) in June 1978, using the DOE 7A FRP Plywood Storage Containers. The fire tests showed that when subjected to a substantial ignition source, the boxes will propagate fire as long as no fire-suppression measures are taken. Fire will breach the boxes and spread the radioactive contaminated waste if it is not extinguished. As the fire progresses, additional boxes will become involved, and eventually the entire storage array will ignite. It is recommended that the use of DOT 7A Boxes be discontinued and replaced with noncombustible storage containers. In the event this is not practicable, guidance recommendations are presented to minimize the large fire loss potential. It is also recommended that an investigation be conducted into the number of boxes that can be destroyed and still maintain a safe environment for employees and the public. This investigation should include how far radioactive contamination will spread, what cleanup will be required, anticipated exposure of the people within the area, and the public impact of such a fire
大板梁翼板对接焊缝的超声波检测%Ultrasonic Testing on Butt Weld of Wing Plate of Main Girder
唐垚; 喻星星
2015-01-01
The ultrasonic testing method of the butt weld of the wing plate with a thickness of 140 mm of the main girder in the utility boiler is introduced. The selection of the probe, the determination of the scanning method in the detection process and the method for depicting the DAC curve using the CSK-Ⅳ test block are mainly discussed.%介绍了电站锅炉大板梁140 mm厚翼板对接焊缝的超声波检测方法. 主要论述了检测过程中探头的选取、 扫查方式的确定以及利用CSK-Ⅳ试块制作DAC曲线的方法.
Testing of packings for stuffing boxes
The stuffing box packings function when they are sealed tight and do not obstruct the movement of the spindle. Characteristic values are necessary to characterise the materials properties of stuffing box packings. Essentially, the definitions of the characteristic values are known and can be calculated in experimental setups. It is absolutely necessary to standardise the characteristic values as well as the testing procedures in order to be able to provide comparable and reproduceable characteristic values. Depending upon the importance of the fittings, it is necessary to guarantee sufficiently exact and reliable assembly for defined operating conditions. (orig.)
Cereal Box Design: An Interdisciplinary Graphics Activity
Fitzgerald, Mike; Tsosie, Teri
2012-01-01
The cereal box design activity is intriguing both for its simplicity and the resourcefulness that it can generate in young people. Also, it lends itself to a variety of curriculums. It covers both consumerism and Design for the Environment (DfE) concepts broadly and in depth. The activity introduces a wide range of topics. They include graphic…
Study of WATCH GRB error boxes
Gorosabel, J.; Castro-Tirado, A. J.; Lund, Niels;
1995-01-01
We have studied the first WATCH GRB Catalogue ofγ-ray Bursts in order to find correlations between WATCH GRB error boxes and a great variety of celestial objects present in 33 different catalogues. No particular class of objects has been found to be significantly correlated with the WATCH GRBs....
Evidence is presented for Hawking's viewpoint that in an insulated box in thermal equilibrium, black holes should form and evaporate in a statistically time-symmetric way. In particular, it is shown that if a black hole can evaporate adiabatically, it is much more likely to form adiabatically than by Jeans instability. (author)
Safety evaluation for packaging CPC metal boxes
This Safety Evaluation for Packaging (SEP) provides authorization for the use of Container Products Corporation (CPC) metal boxes, as described in this document, for the interarea shipment of radioactive contaminated equipment and debris for storage in the Central Waste Complex (CWC) or T Plant located in the 200 West Area. Authorization is granted until November 30, 1995. The CPC boxes included in this SEP were originally procured as US Department of Transportation (DOT) Specification 7A Type A boxes. A review of the documentation provided by the manufacturer revealed the documentation did not adequately demonstrate compliance to the 4 ft drop test requirement of 49 CFR 173.465(c). Preparation of a SEP is necessary to document the equivalent safety of the onsite shipment in lieu of meeting DOT packaging requirements until adequate documentation is received. The equivalent safety of the shipment is based on the fact that the radioactive contents consist of contaminated equipment and debris which are not dispersible. Each piece is wrapped in two layers of no less than 4 mil plastic prior to being placed in the box which has an additional 10 mil liner. Pointed objects and sharp edges are padded to prevent puncture of the plastic liner and wrapping
Choreographies with Secure Boxes and Compromised Principals
Carbone, Marco; Guttman, Joshua
We equip choreography-level session descriptions with a simple abstraction of a security infrastruc- ture. Message components may be enclosed within (possibly nested) ”boxes” annotated with the intended source and destination of those components. The boxes are to be implemented with cryp...
RELIABILITY BASED DESIGN OF A GEAR BOX
D.MADHUSEKHAR
2014-08-01
Full Text Available Reliability is the probability that a system, component or device will perform without failure for a specified period of time under specified operating conditions. The concept of reliability is of great importance in the design of various machine members. Conventional engineering design uses a deterministic approach. It disregards the fact that the material properties, the dimensions of the components and the externally applied loads are statistical in nature. In conventional design this uncertainties are covered with a factor of safety, which is not always successful. The growing trend towards reducing uncertainty and increasing reliability is to use the probabilistic approach. In the present work a three shaft four speed gear box and six speed gear box are designed using reliability principles. For the specified reliability of the system (Gear box, component reliability (Gear pair is calculated by considering the system as a series system. Design is considered to be safe and adequate if the probability of failure of gear box is less than or equal to a specified quantity in each of the two failure modes. . All the parameters affecting the design are considered as random variables and all the random variables are assumed to follow normal distribution. A computer program in C++ is developed to calculate the face widths in bending and surface failure modes. The larger one out of the two values is considered. By changing the variations in the design parameters, variations in the face widths are studied.
Nondestructive assay of boxed radioactive waste
This paper describes the problems related to the nondestructive assay (NDA) of boxed radioactive waste at the Hanford Site and how Westinghouse Hanford company (WHC) is solving the problems. The waste form and radionuclide content are described. The characteristics of the combined neutron and gamma-based measurement system are described
A white box perspective on behavioural adaptation
Bruni, Roberto; Corradini, Andrea; Gadducci, Fabio; Lluch Lafuente, Alberto; Vandin, Andrea
We present a white-box conceptual framework for adaptation developed in the context of the EU Project ASCENS coordinated by Martin Wirsing. We called it CoDA, for Control Data Adaptation, since it is based on the notion of control data. CoDA promotes a neat separation between application and...
PVC posting bags for glove boxes
This specification covers the materials, measurements and manufacture of unpigmented PVC posting bags for use on glove boxes, together with methods of testing the materials. These bags are used in the handling of radioactive and toxic materials of a hazardous nature and therefore must be of the highest standard of mechanical strength, leak tightness and general finish. (author)
折线形腹板钢梁的局部承压性能有限元分析%The finite element analysis on folded web steel girder under patch loading
庄晖; 黄炳生
2012-01-01
The steel beams with folded webs are produced by substituting the folded webs for flat webs, this is a kind of the steel girders with corrugation webs. And such products have superior load-carrying capacity and favorable economic advantages. At present,studies on the behavior of the steel girders under patch loading are scarce at home and abroad. So this paper presents the finite element analysis on folded wed steel girders under patch loading. Observe the failure of the models and the factors that influence the ultimate capacity. Prepare for the text success.%折线形腹板钢梁是将传统钢梁中的平腹板用折线形钢板来代替,是波纹腹板钢梁的一种.该钢梁具有较高的承载力及良好的经济优势.目前,在国内外仅对梯形腹板钢梁的局部承压性能有少量研究.本文作者采用有限元方法对折线形腹板钢梁局部承压性能进行研究,了解其在实际试验中可能发生的破坏模式和各因素对其局部承压力性能的影响,并为今后试验作准备.
任钢; 肖杰; 丁颖
2012-01-01
In terms of 64m through semi-combined plate girder bridge which is used more widely at present,the effect of coupling stiffness between concrete steel truss girder and distribution distance of shear key on concrete slab is analyzed and compared by changing the coupling stiffness and distribution distance.The calculation shows that with the increase of coupling stiffness axial stress of concrete slab increases while beading stress is slightly affected.By decreasing the distribution distance of shear key,stress of concrete slab at the upside of longitudinal girder is largely affected and the stress at the edge while along the center line is slightly affected.%针对目前高速铁路应用较多的64m下承式板桁半结合桥,通过改变混凝土与钢桁梁之间连接刚度以及剪力键分布距离来分析比较其对混凝土应力的影响,计算表明,连接刚度的增加,混凝土板的轴向应力随之增加,但弯曲应力影响较小。通过剪力键布置间距减小,纵梁上方处混凝土板应力影响较大,而混凝土边缘以及中心线处应力影响较小。
Grey-box modelling of pharmacokinetic/pharmacodynamic systems
Tornøe, Christoffer Wenzel; Jacobsen, Judith L; Pedersen, Oluf;
2004-01-01
Grey-box pharmacokinetic/pharmacodynamic (PK/PD) modelling is presented as a promising way of modelling PK/PD systems. The concept behind grey-box modelling is based on combining physiological knowledge along with information from data in the estimation of model parameters. Grey-box modelling...
49 CFR 230.103 - Tender roller bearing journal boxes.
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Tender roller bearing journal boxes. 230.103... Locomotives and Tenders Running Gear § 230.103 Tender roller bearing journal boxes. Tender roller bearing journal boxes shall be maintained in a safe and suitable condition....