Elasto-Plastic Soil-Structure Interaction Analysis of Building Frame-Soil System

The conventional building frame analysis is carried out assuming unyielding supports and ignoring the interactive response of supporting soil media. In fact, the building frame and its foundation along with the soil mass on which it rests together constitute a single integral compatible structural unit to resist the loads. A proper idealization of the building frame-foundation-soil system is thus needed for accessing the realistic and more accurate analysis. The interaction system analyzed in this way yields a rational structural behavior as the shear forces and bending moments get significantly altered due to the resulting differential settlements of soil mass. In addition to this, the constitutive relationship of the soil mass also plays an important role. The paper presents the elasto-plastic interaction analysis of two-bay two-storey plane frame-foundation beam-soil system using the finite element method. The superstructure is considered to behave in linear elastic manner whereas the soil mass to behave in elasto-plastic manner and to yield according to various yields criteria. The settlements in soil mass, contact pressure below foundation beam, forces in the frame members and the foundation beam are evaluated and collapse load is determined considering various yield criteria. The results of the elasto-plastic analysis are compared with conventional analysis