Effect of Soil Foundation Structure Interaction on Seismic Behaviour of Pile Supported Frame Buildings

Abstract

The main objective of this research is to contribute to the understanding of the seismic performance of superstructure by considering the complex dynamic interaction between superstructure, the pile foundation and the soil. As the dynamic response of the structure and the pile to large extent is inelastic, the primary focus is on studying the behavior of superstructure by modeling the nonlinearities of soil and modeling the interface between pile and soil. newlineTo address this problem, a Finite Element Method is used to model soil structure interaction analysis of pile supported framed structures by programming in MATLAB R2009a using Direct Method. To understand this complex behavior of Soil Foundation Structure Interaction (SFSI) a five storey pile supported frame structure is modeled and its inelastic behavior under strong earthquake excitations is studied. A comparison of linear and nonlinear responses and the effect / significance of soil inelasticity on the structural response are commented. Also a parametric study has been carried out to know the response of pile and pile supported framed buildings with and without interface elements. newlineBesides this, the change in response of a high rise structure when a group of adjacent pile supported structures are present under seismic excitation is also studied (Structure Soil Structure Interaction (SSSI)). Different case studies are considered, namely 1. the group effect of structures supported on piles (like group of two or three identical structures and group of three different structures), 2. the effect of variability in structure height (like 5, 10 and 15 storey structure) and 3. the effect of variability in structure shape are considered. For each case, the SSSI response is compared with the conventional fixed base response to understand the significance of SSSI. newlineQuantitative conclusions of this study states that a reasonable seismic analysis for high rise buildings supported on pile foundations is needed to produce a safe and economic design.