Seismic response and design method of single large span structures to spatially random ground motions

Abstract

This article aims at studying the seismic response rules and design method of single large span structures to spatially varying ground motions. A corrected earthquake power spectral density model is first proposed and applied to the following solution process. The practical solution form of the multi-support pseudo excitation method is put forward and used to analyze the seismic response. The total response is divided into the pseudo-static and relative dynamic response. A simplified single large span structural model is used as the research object to study the response law when both the wave-passage effect and incoherence effect are considered. The result shows that the wave-passage effect and incoherence effect can both increase the pseudo-static response. The relative dynamic response is influenced by the form of trigonometric function, while wave-passage frequency influences the period and coherence function results in amplitude attenuation. When the ratio of natural frequency to wave-passage frequency equals to 0.5  n ( n = 0, 1, 2,…), the structural seismic response reaches extreme value. Based on the derived response law, a method of quickly determining the most unfavorable conditions of the multi-support excitation effect is proposed for seismic design of single large span structures.