Seismic Behavior of Connections Subjected to Punching Shear in Flat-Slab Systems

Flat-slab structural systems have a large applicability due to their functional and economic advantages. Initially, the reinforced concrete flat slabs had drops and columns with capitals and were considered to be the structures of choice for warehouse construction and heavy loads because shear was not a problem. Flat plates were subsequently developed, with no drops and no column capitals and due to cheaper formwork required, they were popular for residential and office buildings. Flat plate slabs exhibit higher stress at the column connection and are most likely to fail due to punching shear rather than flexural failure. To avoid shear failure, parameters influencing the punching strength need to be clearly investigated by realistic analytical or experimental studies. The present analytical study investigates the influence of some of the parameters governing the behavior of connections under punching shear, which are concrete strength, column aspect ratio, slab thickness and gravity loading. Computer program Structural Analysis Program 2000 V14 is used to model columns and slabs as frame and shell elements, respectively. Parametric studies on aspect ratio and depth-to-span ratio have been carried out using displacement control non-linear static pushover analysis to investigate the influence of these parameters on punching shear capacity of the intermediate and corner column connections, which proved to be the governing criteria to prescribe drift limits for flat plate systems in seismic zones.