Experimental, analytical and numerical investigation on the effects of different shear reinforcement on residual post-fire behavior of reinforced concrete deep beams

The current research presents findings from a study that conducted an experimental exploration of the comparative structural behaviors of deep beams composed of reinforced concrete when subjected to fire, aiming to analyze the residual post-fire performance of the beams. To this end, eleven full-scale deep beams were fabricated using two different strength classes of concrete. Eight specimens underwent testing subsequent to being exposed fire, while the remaining were tested under room temperature conditions as control samples. The key variables that influenced the experiments included the type and quantity of shear reinforcement, the compressive strength of the concrete, and the shear span-to-depth ratio. The outcomes of the experimental investigation reveal a shift in the failure mode of specimens following exposure to fire and also experiencing a reduction in their maximum load capacity of all fired specimens. The results indicate that the elimination of horizontal shear reinforcement enhances ductility in high-strength concrete deep beams after being subjected to fire, whereas it diminishes ductility in deep beams made of normal-strength concrete. Notably, a novel analytical approach based on the strut-and-tie method was developed for the first time to accurately estimate the ultimate capacity of deep beams post-fire exposure.