Static and Dynamic Axial Response of Drilled Piers. II: Numerical Simulation

Abstract

Realistic time history simulation of drilled pier/pile-soil systems under dynamic and static loading is essential for the development of effective performance-based earthquake designs of deep foundations. This paper presents the results of the numerical simulation of a series of static and dynamic tests on drilled piers performed at the University of California, Berkeley. A nonlinear soil model was implemented based on multiaxial cyclic bounding-surface plasticity within a general finite-element framework, OpenSees. The model requires a small number of parameters that can be easily obtained through conventional site investigations. The results of the simulations show that the model can reasonably simulate nonlinear response of the soil and that it does a good job of capturing the actual load deformation curves obtained from in situ dynamic and static pier load tests. Although the model is suitable for a fully nonlinear total stress analysis of soil-pile systems under multidirectional shaking, further studies are needed to enhance the model capacity by incorporating the cyclic stiffness and strength degradation caused by full stress reversals.