Does the 1D Assumption Hold for Site Response Analysis? a Study of Seismic Site Responses and Implication for Ground Motion Assessment Using Kik-Net Strong-Motion Data

Date: 4/25/2019

Time: 06:00 PM

Room: Grand Ballroom

The one-dimensional (1D) approach is still the prevailing methodology to incorporate site effects in ground response analysis and ground motion modelling. To bridge the 1D to multidimensional site response analysis, we have developed quantitative criteria and a reproducible method to identify sites with significant deviations from 1D behaviour. For KiK-net, we found that 158 out of 354 show two- and three-dimensional (2D/3D) effects, extending the resonance towards shorter periods at which 2D/3D site effects exceed those of the classical 1D configurations and imposing an additional amplification to that due to the impedance contrast alone. Such 2D/3D effects go along with a large within-station ground motion variability. These effects are found to be more pronounced for small impedance contrasts. While it is hardly possible to identify common features in ground motion behaviour for stations with similar topography typologies, it is not over-conservative to apply a safety factor to account for 2D/3D site effects in ground motion modelling.

Presenting Author: Marco Pilz

Authors