Dynamic Analysis of Pile Foundations: Effects of Material Nonlinearity of Soil

 

Bal Krishna Maheshwari

Asst. Professor, Department of Earthquake Engineering, IIT Roorkee, Roorkee, India (Formerly doctoral student Saitama University, Japan) bkmahfeq@iitr.ernet.in

and

Hiroyuki Watanabe

Formerly Professor, Department of Civil & Environmental Engineering, Saitama University, Saitama, Japan

ABSTRACT

Due to soil-structure interaction effects, the dynamic response of pile-supported structures is strongly dependent on the behavior of soil-pile system. A rational design of such structures requires adequate analysis of the soil-pile system. At strong ground excitations behavior of soil surrounding the piles is nonlinear. In this paper, a simplified and computationally efficient technique is presented to incorporate the material nonlinearity of soil in the dynamic analysis of piles. Approach is based on Green’s function formulation and a hyperbolic model is used to define the nonlinear stress-strain relationship for the soil. Effects of material nonlinearity of soil, on the free field response, the seismic response and the impedance functions of pile foundation, are investigated. Analysis is performed both for a single pile and a pile group. It was observed that both seismic response and impedance functions are significantly affected by the nonlinear behavior of the soil media.

Keywords: Soil-pile interaction, material nonlinearity, hyperbolic model, seismic response, impedance functions.

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