Backstay Effect of Diaphragm in Tall Building

Abstract

Seismic analysis of structural systems with floor diaphragms has been a requisite in the recent past. The duty of a structural engineer is to be prudent about the behavior of every structural system adopted. Amongst the structural systems that are adopted world over, diaphragm with rigid and semi-rigid floor plate are adopted widely in the analysis. This research focuses on the backstay effect i.e. podium structural interaction with the tower area and consideration of retaining wall as increment of lateral stiffness as specified in latest tall building code IS6700:2016 for low and high rise structures. In the current study models were prepared with low to high rise storeys with rigid and flexible diaphragms considering backstay diaphragm placing tower at center and corner. The models were subjected to seismic forces; response spectrum along with the combination of the gravity loads. The structural responses like natural periods, base shear, displacement and inter storey drift were also studied.