Study On Seismic Responses Of General Bearings For Reilway Bridges

The relevant provisions of the railway bridge bearings in the current standard'Code for seismic design of railway engineering' are using static analysis method, which only considers the safety checking for fixed bearing, without including systemic seismic design for bearings and the influences of dynamic factors. The relevant seismic design provisions for bearings are simple in the current seismic design code.In this paper, systematic research and comparison analyses on different anti-earthquake codes home and aboard were made, and calculation comparisons of examples were carried out. The comparison analyses provide some meaningful suggestions for learning the advanced experience of the codes of other countries and the revision of'Code for seismic design of railway engineering' in future.Considering the influences of dynamic factors, seismic responses of several typical piers for simple supported railway bridges are calculated based on general FEA program SAP2000 by using response spectrum analysis method and dynamic time history analysis method in this paper. Through the comparisons and analyses of calculation results, the influences of the parameters including the pier stiffness and the mass ratio of the superstructure to substructure on seismic responses of fixed bearings are obtained. The seismic responses are also compared with the results calculated according to'Code for seismic design of railway engineering' and some valuable results are obtained:(1) The effects of pier stiffness and the mass ratio of the superstructure to substructure on seismic responses of fixed bearings for simple supported railway beam bridges are remarkable and some changing rules are found.(2) The horizontal seismic forces of fixed bearings calculated according to present seismic design code are smaller than those obtained by FEA methods. The law of the increasing coefficient, obtained by comparing the dynamic analysis results and the calculated results by the formula from the code, affected by pier stiffness and the mass ratio are obvious. Some suggestions for confirmation of dynamic influence coefficient for the horizontal seismic force checking formula of fixed bearings are provided.