Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper...Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.展开更多
Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very n...Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very necessary.In this study,in order to provide the seismic design and evaluation measure of the bridge structure based on the RSPT,a calculation model of RSPT on bridge under earthquake was established,and the track surface response measure when the derailment coefficient reaches the limit value was calculated by referring to 15 commonly used ground motion(GM)intensity measures.Based on the coefficient of variation of the limit value obtained from multiple GM samples,the optimal measures were selected.Finally,the limit value of bridge seismic response based on RSPT with different train speeds and structural periods was determined.展开更多
Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordi...Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.展开更多
This paper focuses on understanding and evaluating the dynamic effect of the heavy-haul train system on the seismic performance of a long-span railway bridge. A systematic study on the effect of heavy-haul trains on b...This paper focuses on understanding and evaluating the dynamic effect of the heavy-haul train system on the seismic performance of a long-span railway bridge. A systematic study on the effect of heavy-haul trains on bridge seismic response has been conducted, considering the influence of vehicle modeling strategies and dynamic characteristics of the seismic waves. For this purpose, the performance of a long-span cable-stayed railway bridge is assessed with stationary trains atop it, where the heavy-haul vehicles are modeled in two different ways: the multi-rigid body model with suspension system and additional mass model. Comparison of the bridge response in the presence or absence of the train system has been conducted, and the vehicle loading situation, which includes full-load and no-load, is also discussed. The result shows that during the earthquake, the peak moment of the main girder and peak stress of stay cables increase by 80% and by 40% in the presence of fully loaded heavy-haul trains, respectively. At the same time, a considerable decrease appears in the peak acceleration of the main girder. This proves the existence of the damping effect of the heavy-haul train system, and this effect is more obvious for the fully loaded vehicles. Finally, this paper proposes an efficient vehicle modeling method with 2 degrees of freedom(DOF) for simplifying the treatment of the train system in bridge seismic checking.展开更多
Based on Hamilton’s principle, the differential equations of free vibration of track-bridge systems with mortar gap are derived. Hence, a method for calculating the natural frequencies of track-bridge systems is prop...Based on Hamilton’s principle, the differential equations of free vibration of track-bridge systems with mortar gap are derived. Hence, a method for calculating the natural frequencies of track-bridge systems is proposed. The influence of the flexural stiffness of the track-bridge system, the vertical and longitudinal stiffness of the mortar layer,gap position and gap length on the natural frequencies of a track-bridge system is discussed. The results show that the natural frequencies of the track-bridge system are more sensitive to the change of the flexural stiffness of the bridge layer. The change of the longitudinal stiffness of the mortar layer and gap position has no obvious effect on the trackbridge system’s natural frequencies, while the interlayer vertical stiffness has a larger impact. The gap length has a more significant effect on the 4th-5th order natural frequencies of the track-bridge system. The range of the natural frequencies that are affected by the gap widens as the gap length increases.展开更多
China’s high-speed railways are always facing the potential damage risk induced by strong earthquakes.And the route design concept of“using bridge instead of embankment”has also greatly increased the probability of...China’s high-speed railways are always facing the potential damage risk induced by strong earthquakes.And the route design concept of“using bridge instead of embankment”has also greatly increased the probability of high speed trains moving on bridges when a strong earthquake happens.In the past decades,a bunch of theoretical and numerical studies have been conducted in the seismic dynamic field of high-speed railway.However,the effective dynamic test system for verifying the given method and theoretical results is still lacking.Therefore,a novel dynamic test system(DTS)consisting of a shaking table array and a train-pass-bridge reduced-scale model is proposed in this paper.Through some crucial technical problems discussion,the effectiveness of similar design scheme and the feasibility of reduced-scale DTS are elaborated,and then the detailed DTS structures are given and displayed as part-by-part.On this basis,the demonstration tests are conducted and compared with the numerical simulation.The results show that the proposed DTS is accurate and effective.Therefore,the DTS can provide a new physical simulation approach to study the high-speed train’s running safety on bridges under earthquakes and can also provide a reference for the construction of related systems.展开更多
The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation an...The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.展开更多
Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are ess...Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are essential factors affecting SCCBB distortional buckling.Based on the stationary potential energy principle,the analytical expressions for the rotational restraint stiffness(RRS)of the web upper edge as well as the RRS and the lateral restraint stiffness(LRS)of the bottom plate were derived.Also,the SCCBB critical moment formula under the hogging moment was derived.Using twenty specimens,the theoretical calculation method is compared with the finite-element method.Results indicate that the theoretical calculation method can effectively and accurately reflect the restraint effect of the studs,top steel flange,and other factors on the bottom plate.Both the RRS and the LRS have a nonlinear coupling relationship with the external loads and the RRS of the web’s upper edge.Under the hogging moment,the RRS of the web upper edge has a certain influence on the SCCBB distortional buckling critical moment.With increasing RRS of the web upper edge,the SCCBB critical moment increases at first and then tends to be stable.展开更多
基金Projects(52022113,52278546,52108433)supported by the National Natural Science Foundation of ChinaProject(2023QYJC009)supported by the Central South University Research Program of Advanced Interdisciplinary Studies,ChinaProject(2023ZZTS0364)supported by the Fundamental Research Funds for the Central Universities,China。
基金Projects(52078487,U1934207,52178180)supported by the National Natural Science Foundations of ChinaProjects(2022YFB2302603,2022YFC3004304)supported by the National Key Research and Development Program of China+2 种基金Project(2022TJ-Y10)supported by the Hunan Province Science and Technology Talent Lifting,ChinaProject(SKL-IOTSC(UM)-2021-2023)supported by the Science and Technology Development Fund,ChinaProject(SKL-IoTSC(UM)-2024-2026/ORP/GA08/2023)supported by the State Key Laboratory of Internet of Things for Smart City(University of Macao),China。
基金Projects(52022113,52278546)supported by the National Natural Science Foundation of ChinaProject(2020EEEVL0403)supported by the China Earthquake Administration。
文摘Sudden earthquakes pose a threat to the running safety of trains on high-speed railway bridges,and the stiffness of piers is one of the factors affecting the dynamic response of train-track-bridge system.In this paper,a experiment of a train running on a high-speed railway bridge is performed based on a dynamic experiment system,and the corresponding numerical model is established.The reliability of the numerical model is verified by experiments.Then,the experiment and numerical data are analyzed to reveal the pier height effects on the running safety of trains on bridges.The results show that when the pier height changes,the frequency of the bridge below the 30 m pier height changes greater;the increase of pier height causes the transverse fundamental frequency of the bridge close to that of the train,and the shaking angle and lateral displacement of the train are the largest for bridge with 50 m pier,which increases the risk of derailment;with the pier height increases from 8 m to 50 m,the derailment coefficient obtained by numerical simulations increases by 75% on average,and the spectral intensity obtained by experiments increases by 120% on average,two indicators exhibit logarithmic variation.
基金Projects(U1934207, 52078487, 51778630) supported by the National Natural Science Foundation of ChinaProject(2019RS3009) supported by the Innovative Provincial Construction Project of Hunan,ChinaProject(2022ZZTS0150) supported by the Fundamental Research Funds of the Central Universities,China
基金Projects(U1934207,51778630,11972379)supported by the National Natural Science Foundation of ChinaProject(2020zzts148)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(GJJ200657)supported the Research Project of Jiangxi Provincial Education Department,China。
文摘Due to the wide railway network and different characteristics of many earthquake zones in China,considering the running safety performance of trains(RSPT)in the design of high-speed railway bridge structures is very necessary.In this study,in order to provide the seismic design and evaluation measure of the bridge structure based on the RSPT,a calculation model of RSPT on bridge under earthquake was established,and the track surface response measure when the derailment coefficient reaches the limit value was calculated by referring to 15 commonly used ground motion(GM)intensity measures.Based on the coefficient of variation of the limit value obtained from multiple GM samples,the optimal measures were selected.Finally,the limit value of bridge seismic response based on RSPT with different train speeds and structural periods was determined.
基金Projects(51408449,51778630)supported by the National Natural Science Foundation of ChinaProject(2018zzts189)supported by the Fundamental Research Funds for the Central Universities,China
文摘Corrugated steel web is folded along the longitudinal direction and has the mechanical properties such as axial compression stiffness corrugation effect, shear modulus corrugation effect, similar to that of an accordion. In order to study the lateral-torsional buckling of box beams with corrugated steel webs (BBCSW) under the action of bending moment load, the neutral equilibrium equation of BBCSW under the action of bending moment load is derived through the stationary value theory of total potential energy and further, along with taking Kollbrunner-Hajdin correction method and the mechanical properties of the corrugated web into consideration. The analytical calculation formula of lateral-torsional buckling critical bending moment of BBCSW is then obtained. The lateral-torsional buckling critical bending moment of 96 BBCSW test specimens with different geometry dimensions are then calculated using both the analytical calculation method and ANSYS finite element method. The results show that the analytical calculation results agree well with the numerical calculation results using ANSYS, thus proving the accuracy of the analytical calculation method and model simplification hypothesis proposed in this paper. Also, compared with the box beams with flat steel webs (BBFSW) with the same geometry dimensions as BBCSW, within the common range of web space-depth ratio and web span-depth ratio, BBCSW’s lateral-torsional buckling critical bending moment is larger than that of BBFSW. Moreover, the advantages of BBCSW’s stability are even more significant with the increase of web space-depth ratio and web depth-thickness ratio.
基金Project(51678576) supported by the National Natural Science Foundation of ChinaProject(2017YFB1201204) supported by the National Key R&D Program of China。
文摘This paper focuses on understanding and evaluating the dynamic effect of the heavy-haul train system on the seismic performance of a long-span railway bridge. A systematic study on the effect of heavy-haul trains on bridge seismic response has been conducted, considering the influence of vehicle modeling strategies and dynamic characteristics of the seismic waves. For this purpose, the performance of a long-span cable-stayed railway bridge is assessed with stationary trains atop it, where the heavy-haul vehicles are modeled in two different ways: the multi-rigid body model with suspension system and additional mass model. Comparison of the bridge response in the presence or absence of the train system has been conducted, and the vehicle loading situation, which includes full-load and no-load, is also discussed. The result shows that during the earthquake, the peak moment of the main girder and peak stress of stay cables increase by 80% and by 40% in the presence of fully loaded heavy-haul trains, respectively. At the same time, a considerable decrease appears in the peak acceleration of the main girder. This proves the existence of the damping effect of the heavy-haul train system, and this effect is more obvious for the fully loaded vehicles. Finally, this paper proposes an efficient vehicle modeling method with 2 degrees of freedom(DOF) for simplifying the treatment of the train system in bridge seismic checking.
基金Projects(U1934207,52078487,51778630) supported by the National Natural Science Foundation of ChinaProject(502501006) supported by the Fundamental Research Funds for the Central Universities,China+1 种基金Project(2019RS3009)supported by the Hunan Innovative Provincial Construction Project,ChinaProjects(HJGZ20211003,HJGZ20212009)supported by State Key Laboratory of Performance Monitoring and Protecting of Rail Transit Infrastructure,China。
文摘Based on Hamilton’s principle, the differential equations of free vibration of track-bridge systems with mortar gap are derived. Hence, a method for calculating the natural frequencies of track-bridge systems is proposed. The influence of the flexural stiffness of the track-bridge system, the vertical and longitudinal stiffness of the mortar layer,gap position and gap length on the natural frequencies of a track-bridge system is discussed. The results show that the natural frequencies of the track-bridge system are more sensitive to the change of the flexural stiffness of the bridge layer. The change of the longitudinal stiffness of the mortar layer and gap position has no obvious effect on the trackbridge system’s natural frequencies, while the interlayer vertical stiffness has a larger impact. The gap length has a more significant effect on the 4th-5th order natural frequencies of the track-bridge system. The range of the natural frequencies that are affected by the gap widens as the gap length increases.
基金Projects(51878674,52108433,52022113) supported by the National Natural Science Foundation of ChinaProject(2019RS3009) supported by the Hunan Innovative Provincial Construction,China+2 种基金Project(2021JJ40587) supported by the Hunan Provincial Natural Science Foundation of ChinaProject(21B0309) supported by the Research Foundation of Education Bureau of Hunan Province,ChinaProject(HSR202004) supported by the Open Foundation of National Engineering Research Center of High-Speed Railway Construction Technology,China。
文摘China’s high-speed railways are always facing the potential damage risk induced by strong earthquakes.And the route design concept of“using bridge instead of embankment”has also greatly increased the probability of high speed trains moving on bridges when a strong earthquake happens.In the past decades,a bunch of theoretical and numerical studies have been conducted in the seismic dynamic field of high-speed railway.However,the effective dynamic test system for verifying the given method and theoretical results is still lacking.Therefore,a novel dynamic test system(DTS)consisting of a shaking table array and a train-pass-bridge reduced-scale model is proposed in this paper.Through some crucial technical problems discussion,the effectiveness of similar design scheme and the feasibility of reduced-scale DTS are elaborated,and then the detailed DTS structures are given and displayed as part-by-part.On this basis,the demonstration tests are conducted and compared with the numerical simulation.The results show that the proposed DTS is accurate and effective.Therefore,the DTS can provide a new physical simulation approach to study the high-speed train’s running safety on bridges under earthquakes and can also provide a reference for the construction of related systems.
基金Project(2021RC2011)supported by the Science and Technology Innovation Program of Hunan Province,ChinaProjects(U1934207,52178180)supported by the National Natural Science Foundation of ChinaProject(2021M703648)supported by the China Postdoctoral Science Foundation。
文摘The track geometry is a critical factor that affects the running safety and riding comfort of trains moving on a high-speed railway bridge.This study addresses the mapping relationship between the track deformation and lateral deformations of bridges.Equilibrium equations and natural boundary conditions of the track-bridge system are established based on the energy variational principle,and an analytical solution is derived for the track deformation accounting for lateral bridge deformations.A five-span simply-supported bridge with continuous welded rail has been selected as the case study.The mapping rail deformations are compared to the finite element results,and both results agree well with each other,validating the analytical method proposed in this paper.The influence factors on the mapping rail deformation are further evaluated.Results show that the mapping rail deformation is consistent with the girder displacement at the area that is away from the girder ends when the flexural stiffness ratio between the track and the bridge girder is low.The interlayer stiffness has a significant effect on the mapping rail deformation when the track flexural stiffness is of a high value.
基金Projects(U1934207,52078487,51778630) supported by the National Natural Science Foundations of ChinaProject(502501006) supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2019RS3009) supported by the Hunan Innovative Provincial Construction Project,China。
文摘Restrained distortional buckling is an important buckling mode of steel-concrete composite box beams(SCCBB)under the hogging moment.Rotational and lateral deformation restraints of the bottom plate by the webs are essential factors affecting SCCBB distortional buckling.Based on the stationary potential energy principle,the analytical expressions for the rotational restraint stiffness(RRS)of the web upper edge as well as the RRS and the lateral restraint stiffness(LRS)of the bottom plate were derived.Also,the SCCBB critical moment formula under the hogging moment was derived.Using twenty specimens,the theoretical calculation method is compared with the finite-element method.Results indicate that the theoretical calculation method can effectively and accurately reflect the restraint effect of the studs,top steel flange,and other factors on the bottom plate.Both the RRS and the LRS have a nonlinear coupling relationship with the external loads and the RRS of the web’s upper edge.Under the hogging moment,the RRS of the web upper edge has a certain influence on the SCCBB distortional buckling critical moment.With increasing RRS of the web upper edge,the SCCBB critical moment increases at first and then tends to be stable.
