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
Under high-level earthquakes,bridge piers and bearings are prone to be damaged and the elastoplastic state of bridge structural components is easily accessible in the train-track-bridge interaction(TTBI)system.Conside...Under high-level earthquakes,bridge piers and bearings are prone to be damaged and the elastoplastic state of bridge structural components is easily accessible in the train-track-bridge interaction(TTBI)system.Considering the complexity and structural non-linearity of the TTBI system under earthquakes,a single software is not adequate for the coupling analysis.Therefore,in this paper,an interactive method for the TTBI system is proposed by combining the multi-body dynamics software Simpack and the seismic simulation software OpenSees based on the Client-Server architecture,which takes full advantages of the powerful wheel-track contact analysis capabilities of Simpack and the sophisticated nonlinear analysis capabilities of OpenSees.Based on the proposed Simpack and OpenSees co-simulating train-track-bridge(SOTTB)method,a single-span bridge analysis under the earthquake was conducted and the accuracy of co-simulation method was verified by comparing it with results of the finite element model.Finally,the TTBI model is built utilizing the SOTTB method to further discuss the running safety of HST on multi-span simply supported bridges under earthquakes.The results show that the SOTTB method has the advantages of usability,high versatility and accuracy which can be further used to study the running safety of HST under earthquakes with high intensities.展开更多
Segment sectional model tests are carried out to investigate the wind loading on middle pylon of Taizhou Bridge, which has complicated three-dimensional flow due to its feature of double columns. Through the force mea...Segment sectional model tests are carried out to investigate the wind loading on middle pylon of Taizhou Bridge, which has complicated three-dimensional flow due to its feature of double columns. Through the force measuring tests, aerodynamic force coefficients of every segment of the pylon columns have been obtained. It is found that the tested aerodynamic force coefficients are much smaller than those given by codes. The interference effects of aerodynamic force coefficients between columns of pylon are discussed. The results show that the interference effect is the most evident when the yaw angle is about 30 ° from transverse direction. This kind of interference effect can be described as diminutions in transverse aerodynamic force coefficients and magnifications in longitudinal aerodynamic force coefficients of downstream columns.展开更多
China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than ...China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.展开更多
Considering the CRTS-II track slab,which is commonly used in the Chinese high-speed railway system,a vehicle-track-bridge dynamic analysis method is proposed in which the vehicle subsystem equations are established by...Considering the CRTS-II track slab,which is commonly used in the Chinese high-speed railway system,a vehicle-track-bridge dynamic analysis method is proposed in which the vehicle subsystem equations are established by the rigid body dynamics method,the track subsystem and the bridge subsystem equations are established by the FEM,the wheel-rail contact relation is defined by the corresponding assumption in vertical direction and the Kalker linear creep theory in lateral direction.The in-span spring element is derived to model the track-bridge interaction;the equal-band-width storage is adopted to fit the track structure with multilayer uniform section beam;and the dynamic equilibrium equations are solved by the inter-history iteration method.As a case study,the response of a CRH2 high-speed train transverses a simply-supported bridge with successive 31.5m double bound pre-stress beams is simulated.The result shows that using the vehicle-track-bridge interaction model instead of the vehicle-bridge interaction model helps predict the rotation angle at beam ends and choose an economic beam vertical stiffness.展开更多
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Project(2020EEEVL0403)supported by the China Earthquake AdministrationProjects(51878674,52022113)supported by the National Natural Science Foundation of ChinaProject(2022ZZTS0670)supported by the Fundamental Research Funds for the Central Universities,China。
文摘Under high-level earthquakes,bridge piers and bearings are prone to be damaged and the elastoplastic state of bridge structural components is easily accessible in the train-track-bridge interaction(TTBI)system.Considering the complexity and structural non-linearity of the TTBI system under earthquakes,a single software is not adequate for the coupling analysis.Therefore,in this paper,an interactive method for the TTBI system is proposed by combining the multi-body dynamics software Simpack and the seismic simulation software OpenSees based on the Client-Server architecture,which takes full advantages of the powerful wheel-track contact analysis capabilities of Simpack and the sophisticated nonlinear analysis capabilities of OpenSees.Based on the proposed Simpack and OpenSees co-simulating train-track-bridge(SOTTB)method,a single-span bridge analysis under the earthquake was conducted and the accuracy of co-simulation method was verified by comparing it with results of the finite element model.Finally,the TTBI model is built utilizing the SOTTB method to further discuss the running safety of HST on multi-span simply supported bridges under earthquakes.The results show that the SOTTB method has the advantages of usability,high versatility and accuracy which can be further used to study the running safety of HST under earthquakes with high intensities.
基金National Science and Technology Support Program of China ( No. 2009BAG15B01)Key Pro-grams for Science and Technology Development of Chinese Transportation Industry ( No. 2008-353-332-190 )National Science Foundation( No. 51008233)
文摘Segment sectional model tests are carried out to investigate the wind loading on middle pylon of Taizhou Bridge, which has complicated three-dimensional flow due to its feature of double columns. Through the force measuring tests, aerodynamic force coefficients of every segment of the pylon columns have been obtained. It is found that the tested aerodynamic force coefficients are much smaller than those given by codes. The interference effects of aerodynamic force coefficients between columns of pylon are discussed. The results show that the interference effect is the most evident when the yaw angle is about 30 ° from transverse direction. This kind of interference effect can be described as diminutions in transverse aerodynamic force coefficients and magnifications in longitudinal aerodynamic force coefficients of downstream columns.
基金supported by the National Natural Science Foundation of China (Grant No. 51608542)Project of Science and Technology Research and Development Program of China Railway Corporation (Grant No.2015G001-G)
文摘China railways track structure II (CRTS II) slab ballastless track on bridge is one kind of track structures unique to China. Its main bearing component of longitudinal force is the continuous base plate rather than rail. And the track-bridge interaction is weakened by the sliding layer installed between base plate and bridge deck. In order to study the dynamic response of CRTS II slab ballastless track on bridge under seismic action, a 3D nonlinear dynamic model for simply-supported bridges and CRTS II track was established, which considered structures such as steel rail, fasteners, track plate, mortar layer, base plate, sliding layer, bridge, consolidation, anchors, stoppers, etc. Then its force and deformation features under different intensities of seismic excitation were studied. As revealed, the seismic response of the system increases with the increase of seismic intensity. The peak stresses of rail, track plate and base plate all occur at the abutment or anchors. Both track plate and base plate are about to crack. Besides, the rapid relative displacement between base plate and bridge deck due to the small friction coefficient of sliding layer is beneficial to improve the seismic performance of the system. During the earthquake, a large vertical displacement appears in base plate which leads to frequent collisions between stoppers and base plate, as a result, stoppers may be damaged.
基金supported by the National Basic Research Program of China("973"Project)(Grant No.2013CB036203)the National Natural Science Foundation of China(Grant No.U1134206)+1 种基金the 111 project(Grant No.B13002)the Doctoral Fund of Ministry of Education of China(Grant No.20130009110036)
文摘Considering the CRTS-II track slab,which is commonly used in the Chinese high-speed railway system,a vehicle-track-bridge dynamic analysis method is proposed in which the vehicle subsystem equations are established by the rigid body dynamics method,the track subsystem and the bridge subsystem equations are established by the FEM,the wheel-rail contact relation is defined by the corresponding assumption in vertical direction and the Kalker linear creep theory in lateral direction.The in-span spring element is derived to model the track-bridge interaction;the equal-band-width storage is adopted to fit the track structure with multilayer uniform section beam;and the dynamic equilibrium equations are solved by the inter-history iteration method.As a case study,the response of a CRH2 high-speed train transverses a simply-supported bridge with successive 31.5m double bound pre-stress beams is simulated.The result shows that using the vehicle-track-bridge interaction model instead of the vehicle-bridge interaction model helps predict the rotation angle at beam ends and choose an economic beam vertical stiffness.
