Study Of Pounding Effect And Its Mitigation Measures Of Rigid Frame Bridge Subjected To Strong Earthquakes

With the vigorous development of our high-speed railway industry,there is more and more attention paid to the construction toward high-speed railway bridges.Due to our country located in the earthquake prone zones,the seismic performance of high-speed rail bridges has been the focus of research.This thesis puts the pounding effect occurring in the superstructures as an aim,and analyzes the seismic performances of the bridge and the factors affecting the pounding effect of the bridge systematically.Finally,research the inhibition effect of the bridge's pounding effect taken the interaction between girder and rail and the installation of seismic isolation device.The study is summarized as follows:(1)Establish a high-speed continuous rigid frame bridge model and use nonlinear seismic response analysis method to analyze rigid frame bridge's seismic behavior when with or without consideration of beam-rail interaction.Investigate structural dynamic character and seismic response performance considering the influence of beam-rail interaction or not,and clarify the necessity of pounding effect toward analyzing the seismic performance of bridge structures even considering the interaction of beam-rail interaction.(2)Establish a high-speed continuous rigid frame bridge model considering pounding effect,and research the structure's pounding effect and dynamic response under the action of seismic waves with different peak accelerations and PGA/PGV values.It is revealed that pounding effect can increase axial force of pounding site significantly.The beam-rail interaction can reduce the pounding effect of the structure under strong earthquakes.The increase of earthquake intensity and the decrease of PGA/PGV ratio can increase pounding effect and dynamic response of structure.(3)The influence of stiffness and recovery coefficient of pounding unit,the initial gap between the rigid frame bridge and the longitudinal resistance of the beam track on the pounding effect and seismic response of bridge structure is studied.It is clarified that increasing stiffness and recovery coefficient of pounding unit can increase the pounding effect of superstructure,but has little effect on dynamic response of substructure.The intermediate value of initial gap makes structurure's pounding force and internal force responses of substructure significantly increase.Increasing the longitudinal resistance of the beam track can reduce pounding effect and dynamic response of bridge.(4)According to model of high-speed railway continuous rigid frame bridge considering pounding effect,the restraining effect on bridge's pounding effect is studied under installation of viscous damper and shock transmission unit.The influence of the parameter changes of the two damping devices on the structural pounding effect and dynamic response are discussed.Based on the condition that there is no pounding effect between the joints,the best parameters of the two damping devices are determined considering the factors including the maximum output of the devices,the relative displacement between the joints and the internal force response of pier.