A Study to Observe Effect of Ground Soft Storey on Structural Performance of Multistoried R.C.C Buildings

Abstract

The rapid growth of urban population and the consequent pressure on limited space have considerably influenced city residential development upward resulting in high rise buildings. Now-a-days majority of the high-rise buildings intend to provide spacious open areas (to provide parking facilities, shops, superstores, other special facilities etc.) at the ground floor for the inhabitants of the residence or other commercial buildings. To facilitate this demand of the building owners, the Structural Engineers design building structures avoiding use of infill walls at the functional area of the ground floor, but maintaining the partition walls in the other floors, which results in an asymmetric structural behavior under service loads. These structures are currently getting special attraction to be analyzed for understanding their structural behavior completely. Keeping this scope in mind, the current study aims to investigate structural behavioral pattern of multistoried RCC buildings to observe ground soft storey effect on these buildings. The study is carried out to analyze ten RCC residential buildings (five with soft storey and the other five without soft storey) by means of numerical finite element analysis software ETABS. A number of structural parameters (base shear, time period, drifts, column reaction forces) have been determined involving load combinations of vertical as well as lateral loads in both directions of building plan. Afterwards, each of these attained outputs have been compared for buildings with soft storey and buildings without soft storey for better understanding. It is observed that, in case of time period and base shear, almost similar values are obtained for buildings with a particular height (for buildings with soft storey and buildings without soft storey). For the cases of support reactions of interior, exterior, or corner columns, the buildings without ground soft storey experiences much higher support reaction compared to those with ground soft stories. Overall, buildings with soft storey have higher storey drift values then those without soft storey. Especially for earthquake loads, the storey drift values of buildings with soft storey vary significantly than those of buildings without soft storey. But for wind loads this, variations is not so prominent. The observations found from the present study addresses several important concerns and it also indicates that more study should be carried out to properly reveal the structural behavior of not only the RCC structures, but also steel and steel-concrete composite buildings, buildings with various slab systems (flat slab, flat-plate slabs, waffle slabs etc.).