EFFECTS OF DIFFERENT BACKFILL SOIL TYPES ON DYNAMIC BEHAVIOR OF RECTANGULAR TANK WALL CONSIDERING BACKFILLWALLFLUID INTERACTION

摘要

This study focused on the effects of backfill soil types variation on seismic response of rectangular storage tanks. However, only the exterior wall of the rectangular tank interacts with both backfill and fluid is tackled since each part of the structure shows considerable differences in terms of the loads subjected to along with geometrical and positional differences. Hence, the objectives of this study are to develop a model to determine the response of tank wall under dynamic loading and to examine the commonly encountered backfill effects on dynamic response of rectangular tank wall. Three different backfill soil types, which are classified by Unified Soil Classification System, were chosen to represent the soil properties in the analyses. These are poorly graded gravels (GP), silty gravels (GM) and poorly graded sands (SP). Drucker-Prager material approach is used for elasto-plastic soil behavior, and also nonlinear wall-soil interface behavior including seperation is considered.Fluid-rectangular tank wall-backfill system is modeled with the finite element method considering wall-backfill interaction. In addition to this, the fluid-wall interaction is taken into account using Lagrangian approach. The findings obtained from the study showed that maximum vertical displacements of backfill, lateral and roof displacements, stress responses generally decreased with increasing backfill soil stiffness. However, sloshing displacement is not affected by backfill-wall interaction.