Nonlinear Dynamic Analysis of Pile Groups under Seismic Loading

Abstract

In recent years, the nonlinear response of pile groups under dynamic loading is the most important issue. During this procedure it is necessary to perform the numerical model analysis of pile groups with accounts for the nonlinear soil characteristics, the pile-soil-interaction, and the load-transfer mechanics. With the improvement of the computational efficiency and the program of finite element and finite different element, numerical model has been widely used for analysis the geotechnical practice. In this research, numerical model which using BNWF (Beam-on-Nonlinear-Winkler-Foundation) method with finite element program OpenSEES is developed to study the nonlinear response of pile group. This model is used to predict the response of pile groups of centrifuge tests in silica dry sand. For simplifying the model, using group equivalent pile method to model the pile group in one row in two-dimensions. The equivalent linear earthquake site response approach is performed with 1D site response code DEEPSOIL for obtain the dynamic free field ground motion analysis. The free field site response shows that the calculated results are relatively agree well with measured responses at the longer period and have some difference at lower period, but this incompatibility is considered acceptable. The dynamic nonlinear responses of pile groups shows the dynamic BNWF model with group equivalent pile method can be sensitive and the calculated and measured responses are all have good agreements and perform satisfactorily. For analysis the pile-group-supported structures, the response of pile has no significant influence to the structure during earthquake.