The nonlinear vibrations of soil-pile systems under seismic ground motion

In this paper, a boundary element method (BEM) is developed for the nonlinear dynamic analysis of soil-pile systems accounting for both kinematic and inertial interaction. The column-pile of arbitrary doubly symmetric simply or multiply connected constant cross section is partially embedded in layered viscoelastic profile, undergoing moderate large deflections taking into account the effects of shear deformation and rotary inertia. The column-pile is subjected to seismic action as well as to arbitrarily distributed or concentrated transverse, axial and bending loading. To account for shear deformations, the concept of shear deformation coefficients is used. Five boundary value problems are formulated with respect to the transverse displacements, to the axial displacement and to two stress functions and solved using the Analog Equation Method, a BEM based method. The application of the boundary element technique yields a nonlinear coupled system of equations of motion. The evaluation of the shear deformation coefficients is accomplished from the aforementioned stress functions using only boundary integration. The proposed model takes into account the coupling effects of bending-shear deformations along the member as well as the shear forces along the span induced by the applied axial loading. Numerical examples are solved to illustrate the efficiency and the range of applicability of the developed method