Seismic ground motion incoherency evaluation and numerical simulation based on spatial variability of rock site

Abstract

In this study, the seismic ground motion incoherency evaluation and numerical simulation based on spatial variability of rock site was performed using numerical analysis. To conduct this research, an inhomogeneous rock numerical models of 300 m x 150 m were generated using Finite Element Method (FEM) software, OpenSees. A case matrix based on the coefficient of variation and correlation length, a representative parameters indicating spatial variability, was generated. Through the dynamic numerical analysis, ground motions were obtained for each case, and the ground motion coherency functions were calculated. The empirical coherency function of the Pinyon-Flat site in the western United States was reproduced using numerical analysis, which showed the possibility of developing a coherency function of actual rock site using numerical simulation. And, as a result of the case study analysis, it was found that the spatial variability of the rock mass has a very large effect on the seismic ground motion coherency.