Experimental and Numerical Studies on Setback Buildings Considering the SSI Effect under Seismic Response

R M Thejaswini,L Govindaraju,V Devaraj

doi:10.28991/cej-2021-03091664

Abstract

From the previous studies it is observed that due to the effect of the earthquake, several irregular buildings failed vulnerably. Further the effect of sub soil conditions where these buildings have been founded also play an important role on the seismic response of these buildings. In the past, experimental studies on the seismic response of different setback building configurations have not been carried out. Therefore, in the present study the seismic behaviour of setback buildings considering Soil Structure Interaction (SSI) has been evaluated by conducting experimental and numerical investigations. Buildings with various setback configurations were considered and are designed as pile foundation supported structures. The irregularity index of these building configurations have been determined as per the existing codal provisions. These piles supported buildings representing the prototype structure have been scaled down according to geometric, kinematic and dynamic scaling laws. The scaled building models are subjected to vibrations beyond resonant frequencies using shake table facility. A comparison of the results has been made between experimental and numerical investigations. Based on the study it has been observed that storey displacements of building with regular configurations are higher in comparison with the setback buildings. It is also found that asymmetrical and symmetrical setback buildings having different irregularity indices as per IS:1893-2016 indicate nearly the same displacements at resonant frequencies. Doi: 10.28991/cej-2021-03091664 Full Text: PDF

Highlights

Many Stepped buildings which are vertically irregular in nature have been constructed in order to improve the aesthetic view; these vertically irregular buildings are commonly called as setback buildings
From the computation of the irregularity indices, it is found that setback buildings SB3 and SB4 are having identical irregularity indices as per Eurocode (2004) and ASCE (2005) but different as per IS: 1893-2016
There is a need for further studies to develop generalised procedures to compute irregularity indices

Summary

Introduction

Many Stepped buildings which are vertically irregular in nature have been constructed in order to improve the aesthetic view; these vertically irregular buildings are commonly called as setback buildings. Setback buildings have vertically discontinuities with respect to geometry, due to these sudden reductions in plan along the elevations cause vertical discontinuities that could affect performance of such buildings due to seismological effect, based on the limit condition or the seismic intensity level assumptions, as observed by Michalis et al (2006) [1] in their analytical study. An analytical study carried out considering linear static analysis, on the influence of vertical irregularity on multi-storey structures subjected to dynamic loading, found that torsional response occurred on account of vertical irregularity [4]. Rahman et al (2013) [6] performed linear static and dynamic analysis on G+10 vertically irregular setback structures, and storey deflection, drift, and shear of the structure were determined. This review of various kinds of irregularities indicated that seismic response varies dramatically near irregularities

Objectives

Results

Conclusion