TRANSMITTING BOUNDARIES FOR TRANSIENT ELASTIC RESPONSE IN SOIL-STRUCTURE INTERACTION SYSTEM

摘要

The objective of present work is to investigate the effects of various boundaries in analyzing the problems in dynamic soil-structure interaction (SSI) system. The fixed soil boundaries in the soil structure interaction system under seismic event, reflect the waves which are radiated outward from the excited structure towards infinity. A general and efficient Finite Element method through which an infinite system may be approximated to a finite system for the solution directly in the time domain of transient soilstructure interaction problems is the main concern. A study has been performed here to investigate the effectiveness of various boundaries such as viscous boundaries, transmitting boundary etc. The dynamic response of an elastic block on a homogeneous and on layered half space is studied. The block and the near field soil region are discretised with plane strain finite elements and far field soil region is modeled by transmitting cone boundary in which dashpots are combined with stiffness at the boundary nodes. The SSI system is subjected to transient load of a rectangular pulse either in vertical or in horizontal direction at top surface of the block. The displacement time history responses at the top of the block are compared for the cases of free, fixed and transmitting boundary in graphical form . The transient response of SSI system is evaluated by varying the stiffness of the homogeneous soil. The parametric studies of the SSI system under transient loads are carried out to investigate the effect of stiffness ratio between the soil layers on transient response of the system in a layered half space. The maximum response and the behavior of present responses are compared with that of other investigators in tabular form. The response of block-soil interaction under horizontal and vertical transient load, indicate that the present method is effective compared to other modeling methods.