Effect of Pile Group Configurations on Nonlinear Dynamic Response

A three-dimensional (3D) finite-element program has been developed for the dynamic analysis of pile groups. Soil and pile media have been discretized into 3D isoparametric continuum elements. To simulate the stress transfer between soil and pile under lateral load, surface elements have been introduced at the interface. To avoid the radiation effect due to dynamic loading, it is proposed to use the appropriate boundary conditions with introduction of Kelvin elements at the transmitting boundary. The displacements at each time step are evaluated using the implicit Newmark-beta integration method. In the iterative procedure, stresses at a given Gauss point are first checked and adjusted against a limiting tension criterion, and then these stresses are further checked against a yield criterion. Extra stresses computed during these checks are converted to load vectors that are applied in the next iteration. A parametric study is carried out to consider the effect of pile spacing, number of piles, arrangement of pile, and soil modulus on the response of pile group.