COMPARATIVE STUDY OF FLAT SLAB DESIGN USING VARIOUS INTERNATIONAL CODES

The structural function of beamless floor system is to collect the gravity load and other load such as wind load etc. and to transfer to the vertical structural elements i.e. column through the combined capacity in flexure and shear. In Flat slab, the slab is directly supported on the columns. Moments and shear values are usually the largest over the columns. However, when spans are relatively small and imposed load is low, the thickness of slab can be increased to reduce the stresses at slab-column joint which would result in providing greater effective depth for negative moments occurring near the column. With increasing span and live load intensity, the thickness requirement increases which does not give economical solution. So, to tackle this problem flaring of the column at top is done such that the plan geometry at the column head is similar to that of the column. The column capital is intended primarily to increase the capacity of the slab to resist punching shear. The column capital stiffens the slab, which help in controlling the floor deflection. Thus, the floor span can be increased to some extent. Beyond a certain range of span, further stiffening of the slab is required which is achieved by increasing the slab thickness of the slab panel around the column capital. This portion of the slab is known as drop panel. For flat slabs and flat plates supported directly by columns, shear may be the critical factor in design. In almost all tests of such structures, failures have been due to shear or perhaps shear and torsion. These conditions are particularly serious around the exterior columns. In the present study, attempt has been made to understand different methods of analysis of flat slab and parameters, which governs the design parameters of the flat slab. Attempts have been made to study the provisions of flat slab in well-known international standards such as ACI 318, EC-2 and IS 456:2000.