Influence of spatial variability of ground on seismic response analysis: a case study of Bangkok subsoils

Abstract

The objective of this study was to observe the spatial variation in the geological subsoil condition on the seismic ground response of Bangkok subsoils during the remote 6.8 M w Tarlay earthquake in 2011 in Northern Thailand. A simulation of random locations was initially performed to define the studied locations. The dynamic parameters, such as the soil index properties, shear modulus, and shear wave velocity, were determined from the subsurface modeling of Bangkok subsoils. Next-generation attenuation analysis was performed to define the input ground motion at each investigated site. Non-linear one-dimensional site response analysis was performed to investigate the surface ground motion, amplification factor, and spectral acceleration during short (0.2\xa0s) and long (1\xa0s) time periods. In general, it is important to consider the ground spatial variation in any seismic ground response analysis. The results show that Bangkok subsoils could magnify the seismic wave during an earthquake. For example, in the 2011 Tarlay earthquake, the magnification varied from two- to four-fold. The results from this study can be used to define the microzonation of the ground motion characteristic of Bangkok subsoils, such as the peak ground acceleration and the spectral acceleration, at short and long periods.