Description |
SPASM performs a dynamic analysis for lateral soil-pile behavior implemented in a beam-column. The analytical method enables the study of the lateral response of soil-pile systems under earthquake ground motion. Wave loadings and mudslide effects may also be considered. The single pile member is represented in the analysis by a discrete element mechanical model which is restricted to linearly elastic behavior. Simplified superstructure effects can be simulated by increased stiffness along the pile member within the structural system and by coupled rotational restraints at appropriate joints. All input data for the pile, soil and motion can be freely varied along the length. Stability and accuracy are maintained in the dynamic analysis by the use of an implicit (Crank-Nicolson) type of numerical solution. The soil-pile coupling at each node along the embedded length of the pile is represented by a multi-element assemblage of friction blocks, springs, and dashpots which facilitate the examination of hysteretic soil-pile interaction under earthquake loading. The present nonlinear inelastic soil support model allows either degradation or hardening of resistance as a function of deflection and of the number of reversals of deflection in the range beyond an initially elastic condition. Furthermore, the formation of gaps is allowed in order to properly represent the expected soil-pile interplay in the upper layers of the soil. The computer program is formulated to allow interfacing with either a super-structure program or a free-field motion program. |