Slab effects on building seismic performance: State of the art

Abstract

Several tests have been conducted on Beam-Column-Slab subassemblages since early 1980’s. Traditionally, the floor slab has been neglected or only partially considered as a strength contributing factor for seismic performance of buildings. But the experimental tests have confirmed that the floor slab plays a crucial role in imparting strength and stiffness to a frame when subjected to lateral loads. The underestimation of slab contribution to beam strength is actually detrimental as it reduces the column-beam flexural strength ratio and might trigger a “Strong Beam - Weak Column” failure phenomenon. This state-of-the-art paper briefly discusses the mechanisms of slab action and its influence on behaviour of a moment frame subjected to lateral loads. Several factors that affect the degree of slab participation, like influence of transverse beams and beam growth effect are also mentioned. This paper also discusses a few attempts on quantifying the slab contribution in terms of ‘effective flange width’. Finally, the areas that need further research are highlighted and the need for incorporating slab contribution into building design guidelines is emphasized.