Arch Dam Response to Nonuniform Seismic Input

Abstract

A frequency‐domain investigation into the effects of nonuniform earthquake excitation on the response of a three‐dimensional arch dam‐water‐foundation system is performed. The analysis consists of two parts. First, the free‐field motions of the canyon walls are obtained by the boundary element method after making some simplifying assumptions about the canyon geometry and the earthquake mechanism. In the second part of the analysis, the frequency‐domain response of the dam‐water‐foundation system is computed by the finite element method using the previously determined free‐field excitations. To more concisely quantify the effect of nonuniform seismic input, the frequency‐domain responses are converted into the time domain in the form of standard deviations of the response to a random input with an earthquake‐like frequency content. As shown by an analysis of Pacoima Dam, inclusion of nonuniformity in the stream component of the excitation reduces the dam response, and the effect of nonuniformity in the cross‐stream and vertical components varies, with the potential for a significant increase.