Extension of Algorithm for Support Non-Uniform Record Using Time Domain 3D Boundary Elements Method

It is well established that the seismic ground response of surface topographies may differ from those of free field motion during earthquakes. Although the topography effect on ground response can be crucial when the wavelength is comparable to irregularity dimensions, only a few building codes have considered this issue. This is because of the complex nature of seismic wave scattering by topographical structures, which can only be solved accurately and economically using advanced numerical methods under realistic conditions. Among the numerical methods, the BEM is a very effective tool for dynamic analysis of linear elastic bounded and unbounded media. In this research, a three-dimensional model of the Pacoima dam site is prepared. Time domain 3D boundary element method is used to apply the non-uniform excitation at the dam supports. This model is subjected to the vertically propagating incident S waves. Time delay can be characterized by calculating the value of time delay for which the cross-correlation between two records is maximized. Finally, to obtain the time delay in topographic site, a function considering effective parameters such as the height from the canyon base, wave velocity and predominant frequency, is presented. Furthermore, a code was developed for generating the spatial variation of seismic ground motions.