Proposal for Evaluation Method of Damping Ratio of Railway Viaducts Based on the Amplitude Ratio of the Underground Part to entire Structure

Abstract

At first, it is confirmed that the damping ratio calculated by the strain energy proportional damping method is consistent with the damping ratio evaluated from the microtremor observation of the single column pier. Next, we evaluated the damping ratio of the various type of railway viaducts analytically and proposed the evaluation method of the damping ratio based on the amplitude ratio of underground part to entire structure which is calculated from the primary vibration mode shape. Furthermore, we proposed the evaluation method for seismic nonlinear response of railway viaducts by using the proposed evaluation method of the damping ratio. The nonlinear seismic response considering the proper damping ratio can be obtained by using this method, and the calculation procedure is almost the same as that by using the conventional method. Therefore, this method is effective for evaluating the seismic response of railway viaducts for the seismic design.