Experimental investigation on dynamic characteristics of structures founded on a dispersive soil

Abstract

The objective of this paper is to evaluate the Soil-Structure-Interaction (SSI) effects on the seismic response of structures founded on Shedi soil of Dakshina Kannada. Shedi soil, which is a dispersive type of soil is highly vulnerable to dynamic loading in the saturated condition. Experimental investigations have been carried out on 1:10 scaled single bay three dimensional multistorey building models made of aluminium with its foundation resting on locally available Shedi soil (classifying as sandy silt) and sand in the saturated and dry conditions. The combined system of Soil-Foundation-Structure models is subjected to dynamic loading. The response of the model is measured at each floor level. This structural response is compared with that of a fixed base model to isolate the effect of soil structure interaction. The variations in natural frequency with various parameters such as different types of soil, degree of saturation of soil, number of storeys and the stiffening effect of walls are evaluated. The experimental results are presented and the modifications in dynamic characteristics due to the incorporation of soil flexibility are studied. Free vibration analysis of the three dimensional finite element model of the soil foundation structure system is carried out and the results are compared with the experimentally obtained values.