Residual properties of three-span continuous reinforced concrete slabs subjected to different compartment fires

This paper presents an experimental study on the post-fire residual behavior of continuous reinforced concrete (RC) slabs. The mechanical performance of five post-fire continuous RC slabs is investigated, including load-deflection curves, concrete and reinforcement strains, cracking patterns, and failure modes. The results indicate that the residual material properties of heated compartments and concrete spalling significantly affect the ultimate load and failure mode of the fire-damaged continuous RC slabs. The deflection failure criterion is suitable for determining the ultimate state of each span in fire-damaged continuous RC slabs. Apart from the flexural failure mode, punching shear failure also occurred in the fire-damaged continuous slab, particularly in the span with considerable explosive concrete spalling. Compared with the edge spans, the middle span in the continuous slab tends to exhibit better ductility performance owing to continuity at both supports of the span. In addition, several theoretical methods are used to estimate the residual performance of the tested slabs. The reinforcement strain difference and ACI methods are proposed to help predict the residual limit loads of the post fire continuous RC slabs.