Experimental and Numerical Study on the Behavior of Reinforced Concrete Deep Beams with Normal-Strength and High-Strength Concrete After Being Exposed to Fire

Failure of reinforced concrete deep beams which are main structural elements in bridges and tall buildings is mainly brittle and shear-dominant. Besides, fire incidents, being a major cause of failure in such structures, increase the brittleness of failure in reinforced concrete members. Due to the lack of experimental studies focusing on the parameters affecting the behavior of reinforced concrete deep beams, this paper presents the results of an experimental study on the structural responses of 14 full-scale concrete deep beam after being exposed to ISO 834 fire. The main variables in the experiments were concrete compressive strength ( \(f_{c}^{\prime }\) $f_c^{\prime }$ ), shear span-to-depth ratio (a/d), height of beams, type and ratio of shear reinforcement, and the loading type. Results shows the failure modes change after being exposed to fire. All of the specimens experience a reduction in ultimate capacity. Also, increasing a/d ratio results in a reduction in ultimate capacity as well as transformation of failure mode to less brittle modes. In addition, it was observed that the horizontal shear reinforcement increases the displacement corresponding to ultimate capacity; it also increases the post-fire ductility of members. Furthermore, results show that vertical shear reinforcement improves the ultimate capacity and ductility of members. In addition, by performing image processing, it was observed that the specimens will face a decrease in the maximum crack width after exposure to fire. Also, in order to validate the results of the laboratory study, finite element modeling was used and good agreement was observed between the numerical and laboratory results.