Pushover Analysis of R.C.C. Building Including 3D Soil–Structure Interaction

Abstract

The paper explores the seismic vulnerability parameters of Jorhat Engineering College taking into consideration the effects of the flexibility of supporting soil foundation system. The building is analysed using nonlinear static pushover analysis procedure. The structure is surveyed and 2D drawings detailing the plan and elevation of the building, consisting of 13 structural units, are made using Autodesk AutoCAD. The building is modelled and analysed in SAP 2000^®. Infill wall loads are included, and bare frame study is done for the units. Soil flexibility is considered. The soil type of the location considered for analysis is Type II (medium or stiff soils) as per IS 1893:2016. The flexible base units are modelled by assigning springs to the column bases, the stiffness of which are calculated by Gazeta’s equations as per ATC-40. Translational and rotational degrees of freedom are considered for X-, Y- and Z-axes. Both linear and nonlinear analyses are performed on all the units for both longitudinal and transverse direction loadings. Plastic hinge properties are assigned to the members as per FEMA-356, to identify the critical members which have exceeded their capacities. The displacement-coefficient method given by FEMA-356:2000 is employed to find the target displacement for the pushover analysis. Results of the analyses show variation in the performance of the buildings with flexible base foundations.