Dynamic Characteristics And Seismic Response Analysis Of Long-span X-style Steel-box Arch Bridge

Arch bridge is one of the most commonly used bridges in mountainous areas across deep valley in China.The axial compression ratio of main arch of long span arch bridge is generally high.Seismic design cannot be overly dependent on the ductility design of structures.Appropriate seismic mitigation measures should be taken to reduce the seismic responses of arch bridges.In this thesis,the dynamic characteristics of the Long-span X-style steel-box arch bridge under the action of earthquake and the influence of the seismic isolation measures on the seismic response of the bridge are studied in the following aspects.1.The development of steel box arch bridge at home and abroad and the typical earthquake damage of arch bridge in previous earthquakes are summarized,and the present situation and main problems of the seismic study of steel arch bridge are expounded.The development of bridge isolation technology,the principle of seismic isolation and several commonly used bridge isolation devices are introduced.2.In view of the inconsistent conclusion of the influence of structural design parameters on the dynamic characteristics of the Long-span X-style steel-box arch bridge,this thesis takes the Guan Tang Bridge in Liuzhou,Guangxi as the research object.According to the dynamics theory,selects the appropriate finite element to establish the full bridge space calculation model,and explores and gets the dynamic self vibration of the Long-span X-style steel-box arch bridge.The influence of the inclination of the arch rib,the stiffness of the transverse bracing and the number of the transverse bracing on the natural vibration characteristics of the arch rib is clearly defined.3.The relative motion method(RMM)is applied to realize the multi-point excitation for analysis of traveling wave effect.The seismic response analysis of the bridge considering traveling wave effect is carried out.The response curves of internal force and displacement of each key section of the arch bridge with phase difference are obtained under the action of different phase difference seismic waves,and compared with the seismic response of the bridge under the unanimous excitation,the change law of the structure response of the X-style steel-box arch bridge under the action of traveling wave is obtained.4.Based on the two seismic isolation measures,the layout and design parameters of the two kinds of isolation devices are changed by simulation.The seismic response and change law of Long-span X-style steel-box arch bridge under the different parameters of the damper are calculated and analyzed.At the same time,the calculation results of the two kinds of isolation measures are compared,and the damping effect of the shock reduction device on the whole bridge is analyzed.