Seismic response of bridges considering different ground motion selection methods

Abstract

This paper makes use of different ground motion selection and scaling methods for the identification of predominantly first-mode engineering demand parameters (EDPs) of bridges under earthquake excitation. Two groups of ground motions are selected for this purpose. The first group, expected to result primarily in the first-mode response, is selected using the conditional mean spectrum (CMS) method. The second group, which serves as the reference for comparison, is selected to match a chosen scenario response spectrum. Since the shape of the chosen scenario spectrum allows higher mode response, the ground motions in this second group are considered as the ground motions with higher mode effects. Both groups of ground motions are selected using a method that seeks to match the mean and variance of the target spectrum. Comparison of the nonlinear timehistory analysis responses from the two groups for three chosen ground motion scenarios indicates that higher mode effects are more pronounced on column displacements and deck accelerations than the column shear forces.