Nonlinear analysis of seismic response of a base isolated building on a piled raft foundation with grid-form ground improvement

Abstract

A seismic observation has being carrying out at a building on a piled raft foundation with grid-form ground improvement. The building is located in Tokyo, and the observation records have been successfully obtained during the 2011 off the Pacific Coast of Tohoku Earthquake. The observed earthquake at this site is ranked in a middle scale. A seismic response analysis using a nonlinear ground model is conducted for this record. An elasto-plastic model based on a subloading Mohr-Coulomb model is used for the ground. In this model, the G-γ and h-γ relations are directly used to change the status of the subloading surface. A 3D fine finite element mesh model is used with two directional input motions. The simulation results agree well with the observations. The validity of the nonlinear model for the middle scale earthquake is confirmed.