BEHAVIOUR OF RESTRAINED SIFCON TWO WAY SLABS PART 2: PUNCHING SHEAR

In part 1 of this paper, flexural tests conducted on restrained SIFCON two way slabs were described and the load-deflection responses under flexural loading were reported. Three different types of slabs i.e. SIFCON slabs, FRC slabs and PCC slabs were investigated. It was found that flexural performance of SIFCON slabs is quite superior when compared to FRC and PCC slabs. Among SIFCON slabs those containing twelve percent fibres by volume exhibited excellent load carrying capacities, ductility and energy absorption capacities. In part 2 of the paper, the effect of various volume percentage of steel fibre in SIFCON slab specimens subjected to punching shear was studied. The punching shear load was applied to simulate a column-footing connection. From experimentation, the failure loads, deflection and crack patterns in punching shear were studied. Fibre reinforced concrete (FRC) and plain cement concrete (PCC) slab specimens were used as control specimens. The results reported that SIFCON slabs with 12% fibre volume possess high performance than the other slab specimens in all respects. The experimental results are compared with the ACI and IS codes and the need for separate provisions for SIFCON in punching shear is emphasised. A regression model has been developed to predict the punching shear capacity of SIFCON slabs.