Experimental studies and theoretical analysis of the residual properties of three-span small-scale continuous concrete slabs after a fire

Abstract

This study investigated the effect of travelling fire scenarios, span–thickness ratios, and recurring ages on the post-fire residual behaviour of small-scale continuous reinforced concrete slabs. The mechanical performance of five fire-damaged continuous slabs and one reference slab were investigated, including load–deflection curves, concrete and reinforcement strains, cracking patterns, and failure modes, and the observations were compared with those discussed in companion papers. In addition to considering the boundary restraint and failure criteria, this study proposed a simple ellipse equation to determine the tensile membrane action region and residual ultimate loads of concrete slabs at the limit state. The results indicated that the travelling fire scenario, including the fire direction and time delay, had a slight effect on the residual behaviour of fire-damaged slabs with larger span–thickness ratios. For fire-damaged slabs with larger span–thickness ratios, flexural failure easily occurred with sufficient development of the tensile membrane action. The proposed ellipse method can be used to accurately determine the residual ultimate loads of fire-damaged continuous slabs with large span–thickness ratios.