Seismic input methods in coupled system of train-track-bridge

Abstract

To research the influence of seismic input method on the seismic response of traintrack-bridge system, four methods are adopted to input non-uniform seismic excitation, including direct solving method, relative motion method, large mass method and large stiffness method. Train-track-bridge dynamic analysis models under different seismic input methods are established. Taking rigid frame-continuous composite beam bridge with the span of (48+5×80+48) m as an example, the seismic responses of coupled system of train-track-bridge under different seismic input methods are compared. The results show that the seismic responses of vehicle and bridge system from large stiffness method and direct solving method are the same, derailment coefficients and the rates of wheel load reduction from large mass method are bigger than that from direct solving method, the maximum deviation reaches 44.0% and 26.4%; the derailment coefficients, the rates of wheel load reduction and bridge displacements from relative motion method are smaller than that from direct solving method with maximum deviation of 32.5%, 12.8% and 51.9% respectively. As large stiffness method only requires the input of dynamic displacement time-history, so it is more convenient than direct soling method.