Nonlinear analysis of R.C. Frame-wall system with soil-foundation-structure interaction (SFSI)

Abstract

The aim of the current paper is to evaluate the dynamic soil-structure interaction effects on R.C.
framed buildings with or without shear wall on raft foundation by explicit consideration of structural
nonlinearity and soil-structure interaction as per Indian and Ethiopian seismic codes. To this end, finite
element model (Elastic continuum approach) employed for soil-foundation-structure model. At first,
reinforced concrete buildings being four and eight stories high, resting on rock, dense, stiff and soft soil
types, once with moment resisting and once with concrete shear walls are considered. The total SSI system
is modeled with SAP 2000 V21, and the seismic behavior is evaluated using a nonlinear static analysis. The
analysis is once implemented for fixed-based and once for SSI assumptions. The nonlinear response of
buildings was determined and compared between two cases: fixed-base and SSI conditions. Response
quantities such as SSI effects on the Target displacement, SSI effects on the story drifts, SSI effects on the
plastic hinge mechanisms and rotations obtained from pushover analysis of superstructure. The numerical
findings indicate that incorporating the soil-structure interaction generally increases the top displacements
and plastic hinge rotation, reduces the base shear. Hence, it is very important point is that soil-structure
interaction increases the plastic deformation.