Abstract

Abstract: This presentation discusses a parallel dynamic code which is developed to analyse large-scale seismic soil-pile-structure interaction problems. The dynamic program is developed as part of research programme aimed at studying the effects of earthquakes on pile foundations in soft clay layers. Other aspects of the programme, such as centrifuge model testing, cyclic triaxial and resonant column tests as well as constitutive modeling work will also be briefly outlined. The dynamic code is developed from the source code of a static analysis software GeoFEA. The development work includes modifying the code so that very large problems can be domain-decomposed and analysed on a number of PCs connected via a 10 Gbits/sec high-speed switch. Data transfer between PCs is effected using MPI protocol. Within a single PC, multiple cores can also be used by underlaying the MPI scheme with a hyperthreading scheme, implemented using OpenMP. The parallel scheme is implemented on an element-by-element iterative solution algorithm which obviates the assembly of the global stiffness matrix and can be parallelized readily. This drastically reduces memory requirements. By using multiple PCs on a problem, calculation time is also significantly reduced. This allows very large problems involving millions of degrees-of-freedom to be studied using a cluster of relatively inexpensive PCs. The program is verified by comparison with centrifuge model and ABAQUS results on soil-pile-raft interaction. Then two large scale models are analyzed to simulate the seismic soil-pile-structure interaction.