PERFORMANCE BASED EVALUATION OF FLAT SLAB STRUCTURES WITH SQUARE COLUMNS

Abstract

Most of the reinforced concrete structures comprise of conventional beam-column frames. In the present era, the multi-story structures are given higher priority with lack of availability of land. However, there are limits for the height and weight of the structures. Thus, the construction industry is more concentrated on measures to reduce the weight and height of the storey, without compromising with usable space. The flat slab structures serve the purpose as they are the structures involving slabs directly resting on columns; hence, negating the need for beams, which would consume lot of space and also lead to heavy weight of the structure. Even though, flat slabs are found to be advantageous in functional as well as economic aspects; the key issue with flat slabs is their inability to withstand lateral loads efficiently. In the present study, the seismic behaviour of flat slab structures is studied. The 7 storey building models involving flat slab without drops, with drops and with edge beams are modelled considering both bare frame and brick infill frame structures with square columns. The buildings are located in medium soil cover with seismic zone III. The analysis is performed using ETABS 2013 V13.2. The non-linear behaviour of the building models is studied by pushover analysis, considering FEMA 440 parameters. The prime emphasis is made to consider user defined hinge properties to establish the actual hinging pattern of the members. The performance of the building models is studied by evaluating the parameters like hinge locations, ductility ratio, safety ratio and global stiffness.