Numerical Analysis of Seismic Soil-Pile-Structure Interaction in Soft Soil with Strong Nonlinearity and Its Validation by 1g Shaking Table Test

The failure of pile foundations in recent strong earthquakes showed that the current analysis and design method of pile foundation need improvement. In strong earthquakes, the mechanical behavior of the pile foundations, the surrounding soil and the structure are completely nonlinear. Considerations of their nonlinearities are important in improving the analysis method. In recent years, the nonlinearity of the soil and the piles have become inevitable in the analysis of pile foundations. However, the nonlinearity of the structure is simplified. In this paper, a section of an elevated bridge supported by a 3 × 3 group-pile foundation in model scale is considered. 1g shaking table test and three-dimensional nonlinear dynamic finite element method (FEM) are conducted to investigate the seismic behavior of the mentioned model. In the numerical analysis, a FEM program called DBLEAVES is used. In the numerical modeling, the soil, the piles and the structure are modeled by nonlinear constitutive equations. The purpose of this study is to confirm the accuracy of the mentioned nonlinear analysis method by the 1g shaking table test. The recorded data of the shaking table test are reproduced qualitatively and quantitatively by the numerical test. This implies that the discussed numerical method is a comprehensive tool. Applicability of the method is to study the seismic behavior of piles with a high accuracy. Study of reinforcing of existing piles with the ground improvement is its other applicability.