SIMPLE EVALUATION METHOD OF SEISMIC BEHAVIOR OF RAILWAY BRIDGE USING PERIOD AND STRENGTH OF GROUND AND STRUCTURES

Abstract

 Nonlinear dynamic analysis method is proposed to calculate the seismic response of a railway bridge, in which the behavior of ground and the structure are expressed by a two-degree-of-freedom (2DOF) system. The push-over analyses with respect to the surface ground and the structure are first conducted respectively, and they are characterized by independent two single-degree-of-freedom (SDOF) systems. By coupling these two SDOF systems, it is possible to compose a 2DOF system that can conduct nonlinear dynamic analysis considering both soil and structural behaviors. The effectiveness of the proposed method was confirmed by applying it to a railroad bridge pier and comparing the results with those of a dynamic analysis using a detail space frame model. In addition, a method to improve the accuracy of the nonlinear response spectrum method was also investigated that enables simple evaluation of seismic response values of railroad structures, This method is effective as a method for calculating seismic response values for seismic design because the evaluation considers indispensable parameters with respect to the soil ground and the structure: natural period and strength.