ASSESSMENT OF R.C. FRAMED BUILDINGS WITH SOIL STRUCTURE INTERACTION: AS PER ETHIOPIAN AND INDIAN SEISMIC CODE

Abstract

The dynamic soil-structure interaction effects for RC framed buildings with or without shear wall on raft foundation is evaluated by explicit consideration of structural nonlinearity and soilstructure interaction as per Indian and Ethiopian seismic codes. In the current study, the finite element model (Elastic continuum approach) employed for soil-foundation-structure model. Hence, four and eight number of stories with or without shear wall on raft foundation found on rock, dense, stiff and soft soils are designed and modeled using SAP 2000 v 21. The building studied with or without incorporation of SSI effect. The analysis is carried out in 3 stages: (1) response spectrum analysis, (2) soil-structure interaction analysis, and (3) nonlinear structural analysis (pushover analysis). The response spectrum analysis is used to design the section sizes of the members and a comparison is made according to IS 456: 2000 and ES EN-2. The nonlinear static pushover analysis is used to observe proper structural behavior for defined push displacement. The resulting pushover curves are studied through performance-based design (PBD). Finally, a comparison is made between the behavior of each building in the fixed base condition and SSI condition. This work demonstrates ES ES-2 moments exceed that of the IS 456: 2000 by an average of about 15.58% for beam area of tension reinforcement for span and 15.4% for support. So, Indian code provides a more economical design than Ethiopian code ES EN-2. Moreover, 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 displacement and plastic hinge rotation, reduces the base shear. Hence, it is very important point is that soil-structure increases the plastic deformation.