Nonlinear response of bridges under multi-support excitation

This work presents the results of an extensive numerical study on the nonlinear response of bridges subjected to multi-support seismic excitation. Bridges of varying stiffness and ductility have been designed, as in current engineering practice, for synchronous motion, and have been subsequently analyzed in the non linear range under non-synchronous seismic motion. The purpose of the study has been to assess the effects on the peak inelastic response of bridge structures, and the extent of validity of the q-factor approach for the design. The results show that the bridges designed for synchronous input exhibit an excess of strength in the central piers, while the opposite occurs for the lateral ones, so that in some cases these may have ductility demands as large as twice the q-factor.