Relative Analysis of RC Structures With & Without Base Isolation System for Varied Soil Strata Using SSI Effect

The structural response is highly influenced by Soil Structure Interaction (SSI) under the effect of seismic forces. In this study the response of the structure with varied conditional parameters of soil flexibility have been studied and the behaviour of the structure under these conditions been identified. Different conditions are considered for the analysis; one is substituting support condition at base by spring of equivalent stiffness parameter for different types of soil considered and second by considering the base isolation system under same effect. For SSI study, types of soil which are considered conventionally are Hard, Medium and Soft Soil. The purpose of this study is to carried out the structural response under severe conditions and find its usability under it. Symmetric space frames resting on isolated footing of configurations 5 bays in x and y direction with G+ 5 storeys is considered with fixed base and flexible base with and without different types of base isolator. The spring model is developed by using stiffness equation along all 6 DOF and elastic continuum model is developed by Finite Element Method using Etabs V18. The RSA is carried out in this study as per IS 1893:2016. For more accuracy in results, the additions of base isolation system is also introduced for severe seismic zone which helps to identify the behaviour of the structure in such conditions using lateral load resisting system. The influence of SSI & base isolation system on various structural parameters i.e. natural time period, base shear, roof displacement, drift and overturning moment are presented. The study reveals that the SSI with the base isolation system significantly effects on the response of the structure.