The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analys...The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analysis of bridge inspection materials,the principle of ultrasonic non-destructive testing technology and its adaptability to bridge engineering are elaborated.Subsequently,starting from the preparation work before inspection until damage assessment,the entire process of ultrasonic non-destructive testing is studied,and finally,a technical system of ultrasonic non-destructive testing for bridge engineering that runs through the entire process is formed.It is hoped that this article can provide technical reference value for relevant units in China,and promote the high-quality development of China’s bridge engineering from a macro perspective.展开更多
To address local concrete damage in joint areas at the footing of prefabricated assembled self-centering bridge piers(PASPs)in seismic design,a damage transfer configuration(DTC)was proposed,based on the bridge pier s...To address local concrete damage in joint areas at the footing of prefabricated assembled self-centering bridge piers(PASPs)in seismic design,a damage transfer configuration(DTC)was proposed,based on the bridge pier structure configuration and the mechanism of local damage formation.Integrating the DTC into the PASP,numerical models of a previous experimental reference PASP and a PASP with damage transfer configuration(DTPASP)were established using the finite element software ABAQUS with a concrete damage plasticity(CDP)model.The models were then compared with experimental results regarding damage distribution,hysteresis curves,energy dissipation capacity,the joint opening degree,and residual displacement.The findings indicate that the finite element model developed in this study can well reflect the experimental results of the reference PASP.The incorporation of the DTC proved to be beneficial in preserving structural integrity,bearing capacity,and the functionality of the core structure of bridge piers following an earthquake.Meanwhile,this addition did not exert a significant influence on the seismic behavior of the core structure of the bridge pier.展开更多
This paper conducts practical research on the application of steel fiber reinforced concrete construction technology in road and bridge engineering.The study emphasized in its core advantages of tensile strength,impac...This paper conducts practical research on the application of steel fiber reinforced concrete construction technology in road and bridge engineering.The study emphasized in its core advantages of tensile strength,impact resistance,fatigue resistance and high toughness,and introduces its applications in scenarios such as bridge deck pavement,expansion joints and tunnel opening sections.The key points of construction techniques such as material ratio and fiber selection,mixing,pouring and vibration,as well as quality control difficulties and solutions such as steel fiber dispersion,shrinkage cracks and temperature control was analyzed.The development trends of intelligent material research and development and automated construction technology,and propose application suggestions for engineering design and construction management was discussed in this study,which can serve as a references to improve the quality of road and bridge engineering.展开更多
A multi-level evaluation model for the superstructure of a damaged prestressed concrete girder or beam bridge is established, and the evaluation indices of the model as well as the rating standards are defined. A norm...A multi-level evaluation model for the superstructure of a damaged prestressed concrete girder or beam bridge is established, and the evaluation indices of the model as well as the rating standards are defined. A normal relative function about the evaluation indices of each element is developed to calculate the relative degree, and for each element there are no sub-level elements. When evaluating the elements in the sub-item level or the index level of the model, the weights of elements pertain to one adopted element, taking into account their degrees of deterioration. Since the relative degrees and structure evaluation scales on the damage conditions are applied to characterize the superstructure of damaged prestressed concrete girder bridges, this method can evaluate the prestressed structure in detail, and the evaluation results agree with the Code for Maintenance of Highway Bridges and Culvers （JTG Hll--2004 ）. Finally, a bridge in Jilin province is taken as an example, using the method developed to evaluate its damage conditions, which gives an effective way for bridge engineering.展开更多
In the history of bridge engineering, demand has always been the primary driving force for development. Driven by the huge demand for construction since China’s reform and opening-up, Chinese bridge has leapt forward...In the history of bridge engineering, demand has always been the primary driving force for development. Driven by the huge demand for construction since China’s reform and opening-up, Chinese bridge has leapt forward both quantitatively and qualitatively in three major stages, by completing the transition from “follower” to “competitor,” and nally to “leader.” A new future is emerging for Chinese bridge engi- neering. As an important part of China’s transportation infrastructure, the bridge engineering industry is facing challenges in this new era on how to support the construction of a new form of transportation. This paper provides a summary of the status of bridge technology in China, based on a basic analysis of stock demand, incremental demand, and management demand. It is our belief that the Chinese bridge engi- neering industry must ful ll three outstanding requirements: construction ef ciency, management effec- tiveness, and long-term service. Intelligent technology based on information technology provides a new opportunity for innovation in bridge engineering. As a result, the development path of bridge engineering needs to be changed. This paper puts forward the idea of developing a third-generation bridge project that is characterized by intelligence, and discusses this project’s implications, development focus, and plan. In this way, this work provides a direction for the improvement of the core competitiveness of China’s bridge engineering industry.展开更多
A strong earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008. Shortly after the earthquake, the Turner-Fairbank Highway Research Center of the Federal Highway Administration, in partnershi...A strong earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008. Shortly after the earthquake, the Turner-Fairbank Highway Research Center of the Federal Highway Administration, in partnership with the Research Institute of Highways, the Ministry of Communication of China, led a reconnaissance team to conduct a post-earthquake bridge performance investigation of the transportation system in the earthquake affected areas. The U.S. transportation system reconnaissance team visited the area during July 20 24, 2008. This paper presents the findings and lessons learned by the team.展开更多
To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the gird...To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs. Based on the simplified model four stiffness formulae were deduced according to Hamilton principle. These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively. An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation. The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge. The results show that the errors of frequencies between theoretical analysis and test results are less than 10% mostly, and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stiffness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.展开更多
The steadily growing traffic load has resulted in lots of bridge collapse events over the past decades, especiallyfor short-to-medium span bridges. This study investigated probabilistic and dynamic traffic load effect...The steadily growing traffic load has resulted in lots of bridge collapse events over the past decades, especiallyfor short-to-medium span bridges. This study investigated probabilistic and dynamic traffic load effects on shortto-medium span bridges using practical heavy traffic data in China. Mathematical formulations for traffic-bridgecoupled vibration and probabilistic extrapolation were derived. A framework for extrapolating probabilistic anddynamic traffic load effect was presented to conduct an efficient and accurate extrapolation. An equivalent dynamicwheel load model was demonstrated to be feasible for short-to-medium span bridges. Numerical studies of twotypes of simply-supported bridges were conducted based on site-specific traffic monitoring data. Numerical resultsshow that the simulated samples and fitting lines follow a curve line in the Gumbel distribution coordinate system. Itcan be assumed that dynamic traffic load effects follow Gaussian distribution and the extreme value follows Gumbeldistribution. The equivalent probabilistic amplification factor is smaller than the individual dynamic amplificationfactor, which might be due to the variability of individual samples. Eurocode 1 is the most conservative specificationon vehicle load models, followed by the BS5400 specification. The D60-2015 specification in China and ASSHTOspecification provide lower conservative traffic load models.展开更多
To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristi...To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.展开更多
Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seism...Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seismic responses more accurately, proper analytical models of bearings and shear keys should be developed. Based on a series of cyclic loading experiments and analyses, rational analytical models of laminated elastomeric bearings and shear keys, which can consider mechanical degradation, were developed. The effect of the mechanical degradation was investigated by examining the seismic response of a small-to-medium-span bridge in the transverse direction under a wide range of peak ground accelerations（PGA）. The damage mechanism for small-to-medium-span highway bridges was determined, which can explain the seismic damage investigation during earthquakes in recent years. The experimental results show that the mechanical properties of laminated elastomeric bearings will degrade due to friction sliding, but the degree of decrease is dependent upon the influencing parameters. It can be concluded that the mechanical degradation of laminated elastomeric bearings and shear keys play an important role in the seismic response of bridges. The degradation of mechanical properties of laminated elastomeric bearings and shear keys should be included to evaluate more precise bridge seismic performance.展开更多
Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is d...Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is developed based on .Net platform, with VB.Net, C# language and OpenGL graphic technique. With parameterized modeling method, finite element model of this kind of bridge can be built quickly and accurately, and multi-type element modeling with uniform parameters is realized. With advanced graphic technique, three-dimensional model graph can be real-timely previewed for intuitive data check. With an example of practice project, the accuracy and feasibility of this modeling method and practicality of this software are verified.展开更多
This paper presents the development and testing of a novel internal dissipation connection for the use of post-tensioned rocking columns.The solution is one of the many referring to the dissipative controlled rocking(...This paper presents the development and testing of a novel internal dissipation connection for the use of post-tensioned rocking columns.The solution is one of the many referring to the dissipative controlled rocking(DCR)bridge design philosophy.The internal dissipaters are carefully designed to be cost-effective and reduce the over-all construction cost.The dissipaters are fully threaded,Grade 300 bars connected to the permanent column and foundation longitudinal reinforcement with threaded couplers.In this research,a DCR column is subjected to subsequent earthquake events,and the dissipaters’strain design limits are chosen such that there is no need for replacing after a significant seismic event.The result is a recommended design strain limit of 1.5%for the dissi-paters that guarantees the structural integrity of the DCR column after a seismic event.Additionally,a cumulated strain of 5%is recommended for the dissipaters before replacement is suggested.The proposed connection de-tailing with replaceable internal dissipaters,combined with post-tensioned high strength bars and well-confined concrete,provided self-centring capabilities(no residual displacement),dissipation capacity and significantly less damage in the bridge column than a traditional reinforced concrete solution.展开更多
The fatigue damage mechanism and life prediction on foreign carbon-fiber-reinforced pol-ymer(CFRP)reinforced bridge under high temperature in an asphalt pavement were investiga-ted.First,the subtropical hot and humid ...The fatigue damage mechanism and life prediction on foreign carbon-fiber-reinforced pol-ymer(CFRP)reinforced bridge under high temperature in an asphalt pavement were investiga-ted.First,the subtropical hot and humid construction environment in Bangladesh was introduced under which asphalt mastic bridge deck paving of Bangabandhu Bridge was carried on.Then the strains on a steel bar,concert and CFRP plate were adopted as parameters to investigate the fa-tigue crack evolution,load deflection curve variation characteristic and the CFRP plate stress of reinforced roof girder of the box girder.The girder crack resistance,stiffness and fatigue damage cumulative were analyzed.Finally,according to the laws of the fatigue crack propagation and the failure mode,the corresponding fracture mechanics analysis model was adopted combined with the experimented results,and the crack tip stress intensity factor calculation formula was intro-duced to investigate main fatigue crack propagation of specimens.The results show that the cracking of concrete and the development of the crack are effectively constrained by the CFRP plate in an asphalt layer construction under high-temperature conditions,and the fatigue life of the test beam reinforced with CFRP plates is prolonged to some extent,and the test beam can meet 2 million times the fatigue loading limits after the asphalt pavement construction under high-temperature.The fatigue life is predicted by da/dN-△K curves and crack propagation rate,and the fatigue life calculated by this method is in well agreement with the practical one.展开更多
In the realm of high-speed railway bridge engineering,managing the intricacies of the track-bridge system model(TBSM)during seismic events remains a formidable challenge.This study pioneers an innovative approach by p...In the realm of high-speed railway bridge engineering,managing the intricacies of the track-bridge system model(TBSM)during seismic events remains a formidable challenge.This study pioneers an innovative approach by presenting a simplified bridge model(SBM)optimized for both computational efficiency and precise representation,a seminal contribution to the engineering design landscape.Central to this innovation is a novel model-updating methodology that synergistically melds artificial neural networks with an augmented particle swarm optimization.The neural networks adeptly map update parameters to seismic responses,while enhancements to the particle swarm algorithm’s inertial and learning weights lead to superior SBM parameter updates.Verification via a 4-span high-speed railway bridge revealed that the optimized SBM and TBSM exhibit a highly consistent structural natural period and seismic response,with errors controlled within 7%.Additionally,the computational efficiency improved by over 100%.Leveraging the peak displacement and shear force residuals from the seismic TBSM and SBM as optimization objectives,SBM parameters are adeptly revised.Furthermore,the incorporation of elastoplastic springs at the beam ends of the simplified model effectively captures the additional mass,stiffness,and constraint effects exerted by the track system on the bridge structure.展开更多
In order to study the temperature distribution and the corresponding temperature effects on pre-stressed concrete（PC） curved box girder bridge in Shandong Province, this paper builds and adopts an automatic remote r...In order to study the temperature distribution and the corresponding temperature effects on pre-stressed concrete（PC） curved box girder bridge in Shandong Province, this paper builds and adopts an automatic remote real-time temperature collection system to collect temperature data on site, and further uses the software ANSYS for analysis. Based on the comparisons between the measured data and the simulation results, the following conclusions can be drawn： 1 Our temperature monitoring system is reliable; 2 The corresponding measured data of the web plate and flange plate exposed to the sun, vary more severely than that at other positions, so these plates need higher standard design and construction requirements; 3 In the cold wave where still is sunshine, the box girder temperature effect behaves as sine-like curve.展开更多
This paper takes the right branch main channel Bridge of Huai River Bridge in Huainan as the engineering background, uses the finite element software Midas and the ANSYS to simulate and analyze the jacking constructio...This paper takes the right branch main channel Bridge of Huai River Bridge in Huainan as the engineering background, uses the finite element software Midas and the ANSYS to simulate and analyze the jacking construction of the bridge, and according to the theoretical calculation, the construction monitoring plan is developed, and the stress and deformation of the key section and part of the structure are monitored. Construction monitoring combined with 3 g network and data acquisition module, monitoring data for the real time measurement, the centralized acquisition and wireless transmission, accomplish on-line real-time monitoring of the bridge construction process, effective control of jacking construction and monitoring. The comparison between theoretical analysis and measured results shows that the simulation results are reasonable, and the construction monitoring scheme based on 3G network and data collection can be used as reference.展开更多
The main material of concrete is a construction building material composed of water and mineral mixture and cement and chemical additives in the corresponding proportion and below the standard.In the process of making...The main material of concrete is a construction building material composed of water and mineral mixture and cement and chemical additives in the corresponding proportion and below the standard.In the process of making concrete material,slurry and cement are needed to mix,then cement slurry and sand are mixed into mortar according to the corresponding proportion,and aggregate is added to mortar to form concrete building material.In the process of concrete preparation,the most important construction link is mixing,which needs to be fully stirred to make the performance of concrete meet the construction needs.In the process of concrete construction technology development,both mix ratio and production technology have become more and more mature,but there are still some problems,which have an impact on the quality of concrete[1].Therefore,this paper discusses the quality control of concrete raw materials according to the construction process of road and bridge.展开更多
In order to identify the shortcomings and weaknesses of bridge engineering construction quality in Zhejiang province, this paper firstly selects the quality criteriums of four bridge engineering construction quality c...In order to identify the shortcomings and weaknesses of bridge engineering construction quality in Zhejiang province, this paper firstly selects the quality criteriums of four bridge engineering construction quality criteriums, including concrete durability of outbound construction, construction of large steel box girder, construction of large concrete members and prestressed construction, based on the regional characteristics of Zhejiang province. Then, the quality index of construction projects is analyzed by benchmarking projects in the province, and the gap between the application of high-performance steel, the production and installation technology of steel box girder, the construction equipment of marine concrete components, the installation and tension technology of prestressed pipe and the international advanced level is found. On this basis, the paper puts forward the construction quality improvement strategies in three aspects: design concept, industrial construction level and achievement transformation.展开更多
In order to realize the in-situ evaluation of reinforced concrete bridges subjected to fatigue for a long time or after earthquake, an evaluation method for cumulative damage of concrete structures based on unloading ...In order to realize the in-situ evaluation of reinforced concrete bridges subjected to fatigue for a long time or after earthquake, an evaluation method for cumulative damage of concrete structures based on unloading elastic modulus was proposed. First, according to the concrete stress-strain curve and the statistical relationship between residual strain and cumulative strain, the calculation method of static equivalent strain and residual strain concrete based on unloading elastic modulus and the method for estimating the strength of concrete after damage were proposed. The detailed steps of field test and analysis and the practical damage indicators of residual strain were given. Then, the evaluation method of existing stress and strain of Reinforced Concrete Bridge under dead load and the concept of “equivalent dead load bending moment” were put forward. On this basis, the paper analyzed the root cause of the decrease of bearing capacity of Reinforced Concrete Bridge after fatigue damage, and pointed out that the equivalent strain or residual strain of reinforced concrete increases under the fatigue effect, which led to the decreasing of actual live moment and deformation performance while the ultimate load-carrying capacity remained constant or very little decrease. The evaluation method of structure residual capacity was given, and through comparative analysis of eight T reinforced concrete beams that had been in service for 35 years with the static failure tests, the effectiveness of the method was verified.展开更多
In the maintenance work of highway and bridge engineering structures,the fracture delay of high-strength bolts is a content that needs to be focused on and researched.Based on this,the paper analyzes the fracture dela...In the maintenance work of highway and bridge engineering structures,the fracture delay of high-strength bolts is a content that needs to be focused on and researched.Based on this,the paper analyzes the fracture delay of high-strength bolts in highway bridge maintenance,including an overview of the fundamental research on fracture delay and related specific studies.It is hoped that this study can provide scientific reference for the reasonable maintenance of high-strength bolts,so as to ensure the overall maintenance effect of highway bridge projects.展开更多
文摘The purpose of this study is to analyze the application of ultrasonic non-destructive testing technology in bridge engineering.During the research phase,based on literature collection and reading,as well as the analysis of bridge inspection materials,the principle of ultrasonic non-destructive testing technology and its adaptability to bridge engineering are elaborated.Subsequently,starting from the preparation work before inspection until damage assessment,the entire process of ultrasonic non-destructive testing is studied,and finally,a technical system of ultrasonic non-destructive testing for bridge engineering that runs through the entire process is formed.It is hoped that this article can provide technical reference value for relevant units in China,and promote the high-quality development of China’s bridge engineering from a macro perspective.
基金National Natural Science Foundation of China under Grant Nos.51408359,52278527 and 52478536。
文摘To address local concrete damage in joint areas at the footing of prefabricated assembled self-centering bridge piers(PASPs)in seismic design,a damage transfer configuration(DTC)was proposed,based on the bridge pier structure configuration and the mechanism of local damage formation.Integrating the DTC into the PASP,numerical models of a previous experimental reference PASP and a PASP with damage transfer configuration(DTPASP)were established using the finite element software ABAQUS with a concrete damage plasticity(CDP)model.The models were then compared with experimental results regarding damage distribution,hysteresis curves,energy dissipation capacity,the joint opening degree,and residual displacement.The findings indicate that the finite element model developed in this study can well reflect the experimental results of the reference PASP.The incorporation of the DTC proved to be beneficial in preserving structural integrity,bearing capacity,and the functionality of the core structure of bridge piers following an earthquake.Meanwhile,this addition did not exert a significant influence on the seismic behavior of the core structure of the bridge pier.
文摘This paper conducts practical research on the application of steel fiber reinforced concrete construction technology in road and bridge engineering.The study emphasized in its core advantages of tensile strength,impact resistance,fatigue resistance and high toughness,and introduces its applications in scenarios such as bridge deck pavement,expansion joints and tunnel opening sections.The key points of construction techniques such as material ratio and fiber selection,mixing,pouring and vibration,as well as quality control difficulties and solutions such as steel fiber dispersion,shrinkage cracks and temperature control was analyzed.The development trends of intelligent material research and development and automated construction technology,and propose application suggestions for engineering design and construction management was discussed in this study,which can serve as a references to improve the quality of road and bridge engineering.
文摘A multi-level evaluation model for the superstructure of a damaged prestressed concrete girder or beam bridge is established, and the evaluation indices of the model as well as the rating standards are defined. A normal relative function about the evaluation indices of each element is developed to calculate the relative degree, and for each element there are no sub-level elements. When evaluating the elements in the sub-item level or the index level of the model, the weights of elements pertain to one adopted element, taking into account their degrees of deterioration. Since the relative degrees and structure evaluation scales on the damage conditions are applied to characterize the superstructure of damaged prestressed concrete girder bridges, this method can evaluate the prestressed structure in detail, and the evaluation results agree with the Code for Maintenance of Highway Bridges and Culvers （JTG Hll--2004 ）. Finally, a bridge in Jilin province is taken as an example, using the method developed to evaluate its damage conditions, which gives an effective way for bridge engineering.
文摘In the history of bridge engineering, demand has always been the primary driving force for development. Driven by the huge demand for construction since China’s reform and opening-up, Chinese bridge has leapt forward both quantitatively and qualitatively in three major stages, by completing the transition from “follower” to “competitor,” and nally to “leader.” A new future is emerging for Chinese bridge engi- neering. As an important part of China’s transportation infrastructure, the bridge engineering industry is facing challenges in this new era on how to support the construction of a new form of transportation. This paper provides a summary of the status of bridge technology in China, based on a basic analysis of stock demand, incremental demand, and management demand. It is our belief that the Chinese bridge engi- neering industry must ful ll three outstanding requirements: construction ef ciency, management effec- tiveness, and long-term service. Intelligent technology based on information technology provides a new opportunity for innovation in bridge engineering. As a result, the development path of bridge engineering needs to be changed. This paper puts forward the idea of developing a third-generation bridge project that is characterized by intelligence, and discusses this project’s implications, development focus, and plan. In this way, this work provides a direction for the improvement of the core competitiveness of China’s bridge engineering industry.
基金Turner-Fairbank Highway Research Center of Federal Highway Administration
文摘A strong earthquake occurred in Wenchuan County, Sichuan Province, China, on May 12, 2008. Shortly after the earthquake, the Turner-Fairbank Highway Research Center of the Federal Highway Administration, in partnership with the Research Institute of Highways, the Ministry of Communication of China, led a reconnaissance team to conduct a post-earthquake bridge performance investigation of the transportation system in the earthquake affected areas. The U.S. transportation system reconnaissance team visited the area during July 20 24, 2008. This paper presents the findings and lessons learned by the team.
基金Project(50608008) supported by the National Natural Science Foundation of Chinaproject(20050536002) supported by the Specialized Research Fund for the Doctoral Program of Higher Education
文摘To study the stiffness distribution of girder and the method to identify modal parameters of cable-stayed bridge, a simplified dynamical finite element method model named three beams model was established for the girder with double ribs. Based on the simplified model four stiffness formulae were deduced according to Hamilton principle. These formulae reflect well the contribution of the flexural, shearing, free torsion and restricted torsion deformation, respectively. An identification method about modal parameters was put forward by combining method of peak value and power spectral density according to modal test under ambient excitation. The dynamic finite element method analysis and modal test were carried out in a long-span concrete cable-stayed bridge. The results show that the errors of frequencies between theoretical analysis and test results are less than 10% mostly, and the most important modal parameters for cable-stayed bridge are determined to be the longitudinal floating mode, the first vertical flexural mode and the first torsional mode, which demonstrate that the method of stiffness distribution for three beams model is accurate and method to identify modal parameters is effective under ambient excitation modal test.
基金The research was supported by the National Science Foundation of China(Grant No.51908068)the support from the Key Laboratory of Bridge Engineering Safety Control by Department of Education(Changsha University of Science&Technology).Industry Key Laboratory of Traffic Infrastructure Security Risk Management in Changsha University of Science and Technology(Grant Nos.19KF03,19KB02)Open Fund of Engineering Research Center of Catastrophic Prophylaxis and Treatment of Road&Traffic Safety of Ministry of Education(Grant No.KFJ190403).
文摘The steadily growing traffic load has resulted in lots of bridge collapse events over the past decades, especiallyfor short-to-medium span bridges. This study investigated probabilistic and dynamic traffic load effects on shortto-medium span bridges using practical heavy traffic data in China. Mathematical formulations for traffic-bridgecoupled vibration and probabilistic extrapolation were derived. A framework for extrapolating probabilistic anddynamic traffic load effect was presented to conduct an efficient and accurate extrapolation. An equivalent dynamicwheel load model was demonstrated to be feasible for short-to-medium span bridges. Numerical studies of twotypes of simply-supported bridges were conducted based on site-specific traffic monitoring data. Numerical resultsshow that the simulated samples and fitting lines follow a curve line in the Gumbel distribution coordinate system. Itcan be assumed that dynamic traffic load effects follow Gaussian distribution and the extreme value follows Gumbeldistribution. The equivalent probabilistic amplification factor is smaller than the individual dynamic amplificationfactor, which might be due to the variability of individual samples. Eurocode 1 is the most conservative specificationon vehicle load models, followed by the BS5400 specification. The D60-2015 specification in China and ASSHTOspecification provide lower conservative traffic load models.
基金Projects(20B062,19B054)supported by Excellent Youth Program of Hunan Education Department,ChinaProject(2019JJ50688)supported by Hunan Provincial Natural Science Foundation of ChinaProject(kq195004)supported by Changsha Science and Technology Bureau Project,China。
文摘To study the additional aerodynamic effect on a bridge girder under the action of wind-driven rain, the rainfall similarity considering raindrop impact and surface water is first given. Then, the dynamic characteristics and the process of vortex and flutter generation of the segment models under different rain intensities and angles of attack are tested by considering several typical main girder sections as examples. The test results indicate that the start and end wind speeds,interval length and number of vortex vibrations remain unchanged when it is raining, rainfall will reduce the windinduced vortex response. When test rain intensity is large, the decrease of amplitude is obvious. However, after considering the rain intensity similarity in this study, all of actual maximum rain intensities after conversion approach the domestic extreme rain intensity of approximately 709 mm/h. It can be observed that rainfall has a limited influence on the dynamic characteristics of the structure and vortex vibration response. When the test rain intensity is 120 mm/h, the critical wind speed of the model flutter increases by 20%-30%. However, after considering the rain intensity similarity ratio, the influence of rainfall on the wind-induced flutter instability of the bridge girder may be ignored.
基金Project of China International Science and Technology Cooperation under Grant No.2009DFA82480Science and Technology Project of Communications’ Construction in Western China,MOC under Grant No.2009318223094
文摘Laminated elastomeric bearings have been widely used for small-to-medium-span highway bridges in China, in which concrete shear keys are set transversely to prohibit large girder displacement. To evaluate bridge seismic responses more accurately, proper analytical models of bearings and shear keys should be developed. Based on a series of cyclic loading experiments and analyses, rational analytical models of laminated elastomeric bearings and shear keys, which can consider mechanical degradation, were developed. The effect of the mechanical degradation was investigated by examining the seismic response of a small-to-medium-span bridge in the transverse direction under a wide range of peak ground accelerations（PGA）. The damage mechanism for small-to-medium-span highway bridges was determined, which can explain the seismic damage investigation during earthquakes in recent years. The experimental results show that the mechanical properties of laminated elastomeric bearings will degrade due to friction sliding, but the degree of decrease is dependent upon the influencing parameters. It can be concluded that the mechanical degradation of laminated elastomeric bearings and shear keys play an important role in the seismic response of bridges. The degradation of mechanical properties of laminated elastomeric bearings and shear keys should be included to evaluate more precise bridge seismic performance.
基金National Science and Technology Support Program of China(No.2009BAG15B01)Key Programs for Science and Technology Development of Chinese Transportation Industry(No.2008-353-332-190)
文摘Building a reasonable and accurate finite element model is the first and critical step for structural analysis of complicated bridge. In this article, modeling assistant for continuous suspension with multi-pylon is developed based on .Net platform, with VB.Net, C# language and OpenGL graphic technique. With parameterized modeling method, finite element model of this kind of bridge can be built quickly and accurately, and multi-type element modeling with uniform parameters is realized. With advanced graphic technique, three-dimensional model graph can be real-timely previewed for intuitive data check. With an example of practice project, the accuracy and feasibility of this modeling method and practicality of this software are verified.
文摘This paper presents the development and testing of a novel internal dissipation connection for the use of post-tensioned rocking columns.The solution is one of the many referring to the dissipative controlled rocking(DCR)bridge design philosophy.The internal dissipaters are carefully designed to be cost-effective and reduce the over-all construction cost.The dissipaters are fully threaded,Grade 300 bars connected to the permanent column and foundation longitudinal reinforcement with threaded couplers.In this research,a DCR column is subjected to subsequent earthquake events,and the dissipaters’strain design limits are chosen such that there is no need for replacing after a significant seismic event.The result is a recommended design strain limit of 1.5%for the dissi-paters that guarantees the structural integrity of the DCR column after a seismic event.Additionally,a cumulated strain of 5%is recommended for the dissipaters before replacement is suggested.The proposed connection de-tailing with replaceable internal dissipaters,combined with post-tensioned high strength bars and well-confined concrete,provided self-centring capabilities(no residual displacement),dissipation capacity and significantly less damage in the bridge column than a traditional reinforced concrete solution.
基金funded by the National Natural Science Foundation of China(No.51508368)State High-tech Development Plan of China("863"Program)(No.2012AA03A204)+1 种基金Science and Technology Plan Projects of Jiangsu Provincial Construction Department(No.2015ZD78)Open Project of Structure Engineering Key Laboratory in Jiangsu Province(No.ZD1401)
文摘The fatigue damage mechanism and life prediction on foreign carbon-fiber-reinforced pol-ymer(CFRP)reinforced bridge under high temperature in an asphalt pavement were investiga-ted.First,the subtropical hot and humid construction environment in Bangladesh was introduced under which asphalt mastic bridge deck paving of Bangabandhu Bridge was carried on.Then the strains on a steel bar,concert and CFRP plate were adopted as parameters to investigate the fa-tigue crack evolution,load deflection curve variation characteristic and the CFRP plate stress of reinforced roof girder of the box girder.The girder crack resistance,stiffness and fatigue damage cumulative were analyzed.Finally,according to the laws of the fatigue crack propagation and the failure mode,the corresponding fracture mechanics analysis model was adopted combined with the experimented results,and the crack tip stress intensity factor calculation formula was intro-duced to investigate main fatigue crack propagation of specimens.The results show that the cracking of concrete and the development of the crack are effectively constrained by the CFRP plate in an asphalt layer construction under high-temperature conditions,and the fatigue life of the test beam reinforced with CFRP plates is prolonged to some extent,and the test beam can meet 2 million times the fatigue loading limits after the asphalt pavement construction under high-temperature.The fatigue life is predicted by da/dN-△K curves and crack propagation rate,and the fatigue life calculated by this method is in well agreement with the practical one.
基金Project(2022YFC3004304)supported by the National Key Research and Development Program of ChinaProjects(52078487,U1934207,52178180)supported by the National Natural Science Foundation of China+2 种基金Project(2022TJ-Y10)supported by the Hunan Province Science and Technology Talent Lifting Project,ChinaProject(2023QYJC006)supported by the Frontier Cross Research Project of Central South University,ChinaProject(SKL-IoTSC(UM)-2024-2026/ORP/GA08/2023)supported by the Science and Technology Development Fund and the State Key Laboratory of Internet of Things for Smart City(University of Macao),China。
文摘In the realm of high-speed railway bridge engineering,managing the intricacies of the track-bridge system model(TBSM)during seismic events remains a formidable challenge.This study pioneers an innovative approach by presenting a simplified bridge model(SBM)optimized for both computational efficiency and precise representation,a seminal contribution to the engineering design landscape.Central to this innovation is a novel model-updating methodology that synergistically melds artificial neural networks with an augmented particle swarm optimization.The neural networks adeptly map update parameters to seismic responses,while enhancements to the particle swarm algorithm’s inertial and learning weights lead to superior SBM parameter updates.Verification via a 4-span high-speed railway bridge revealed that the optimized SBM and TBSM exhibit a highly consistent structural natural period and seismic response,with errors controlled within 7%.Additionally,the computational efficiency improved by over 100%.Leveraging the peak displacement and shear force residuals from the seismic TBSM and SBM as optimization objectives,SBM parameters are adeptly revised.Furthermore,the incorporation of elastoplastic springs at the beam ends of the simplified model effectively captures the additional mass,stiffness,and constraint effects exerted by the track system on the bridge structure.
基金Supported by the China Postdoctoral Science Foundation(2013M531560)the Technology Innovation Plan in Traffic of Shandong Province(2012A15)the Science&Technology Development Projects of Shandong Province(2014GSF120015)
文摘In order to study the temperature distribution and the corresponding temperature effects on pre-stressed concrete（PC） curved box girder bridge in Shandong Province, this paper builds and adopts an automatic remote real-time temperature collection system to collect temperature data on site, and further uses the software ANSYS for analysis. Based on the comparisons between the measured data and the simulation results, the following conclusions can be drawn： 1 Our temperature monitoring system is reliable; 2 The corresponding measured data of the web plate and flange plate exposed to the sun, vary more severely than that at other positions, so these plates need higher standard design and construction requirements; 3 In the cold wave where still is sunshine, the box girder temperature effect behaves as sine-like curve.
文摘This paper takes the right branch main channel Bridge of Huai River Bridge in Huainan as the engineering background, uses the finite element software Midas and the ANSYS to simulate and analyze the jacking construction of the bridge, and according to the theoretical calculation, the construction monitoring plan is developed, and the stress and deformation of the key section and part of the structure are monitored. Construction monitoring combined with 3 g network and data acquisition module, monitoring data for the real time measurement, the centralized acquisition and wireless transmission, accomplish on-line real-time monitoring of the bridge construction process, effective control of jacking construction and monitoring. The comparison between theoretical analysis and measured results shows that the simulation results are reasonable, and the construction monitoring scheme based on 3G network and data collection can be used as reference.
文摘The main material of concrete is a construction building material composed of water and mineral mixture and cement and chemical additives in the corresponding proportion and below the standard.In the process of making concrete material,slurry and cement are needed to mix,then cement slurry and sand are mixed into mortar according to the corresponding proportion,and aggregate is added to mortar to form concrete building material.In the process of concrete preparation,the most important construction link is mixing,which needs to be fully stirred to make the performance of concrete meet the construction needs.In the process of concrete construction technology development,both mix ratio and production technology have become more and more mature,but there are still some problems,which have an impact on the quality of concrete[1].Therefore,this paper discusses the quality control of concrete raw materials according to the construction process of road and bridge.
文摘In order to identify the shortcomings and weaknesses of bridge engineering construction quality in Zhejiang province, this paper firstly selects the quality criteriums of four bridge engineering construction quality criteriums, including concrete durability of outbound construction, construction of large steel box girder, construction of large concrete members and prestressed construction, based on the regional characteristics of Zhejiang province. Then, the quality index of construction projects is analyzed by benchmarking projects in the province, and the gap between the application of high-performance steel, the production and installation technology of steel box girder, the construction equipment of marine concrete components, the installation and tension technology of prestressed pipe and the international advanced level is found. On this basis, the paper puts forward the construction quality improvement strategies in three aspects: design concept, industrial construction level and achievement transformation.
文摘In order to realize the in-situ evaluation of reinforced concrete bridges subjected to fatigue for a long time or after earthquake, an evaluation method for cumulative damage of concrete structures based on unloading elastic modulus was proposed. First, according to the concrete stress-strain curve and the statistical relationship between residual strain and cumulative strain, the calculation method of static equivalent strain and residual strain concrete based on unloading elastic modulus and the method for estimating the strength of concrete after damage were proposed. The detailed steps of field test and analysis and the practical damage indicators of residual strain were given. Then, the evaluation method of existing stress and strain of Reinforced Concrete Bridge under dead load and the concept of “equivalent dead load bending moment” were put forward. On this basis, the paper analyzed the root cause of the decrease of bearing capacity of Reinforced Concrete Bridge after fatigue damage, and pointed out that the equivalent strain or residual strain of reinforced concrete increases under the fatigue effect, which led to the decreasing of actual live moment and deformation performance while the ultimate load-carrying capacity remained constant or very little decrease. The evaluation method of structure residual capacity was given, and through comparative analysis of eight T reinforced concrete beams that had been in service for 35 years with the static failure tests, the effectiveness of the method was verified.
文摘In the maintenance work of highway and bridge engineering structures,the fracture delay of high-strength bolts is a content that needs to be focused on and researched.Based on this,the paper analyzes the fracture delay of high-strength bolts in highway bridge maintenance,including an overview of the fundamental research on fracture delay and related specific studies.It is hoped that this study can provide scientific reference for the reasonable maintenance of high-strength bolts,so as to ensure the overall maintenance effect of highway bridge projects.
