Post-fire performance of GFRP reinforced concrete deep beams: experimental and numerical study

Fire resistance of Glass Fiber Reinforced Polymer (GFRP) reinforced concrete members is an important concern in concrete structures. The experimental study of the structural response of GFRP reinforced concrete deep beams exposed to the ISO 834 standard fire is presented in this paper. To this end, a number of 7 specimens including 2 control and 5 fired specimen, have been subjected to monotonic static loading after exposure to fire. Shear span-to-depth ratio (a/d), horizontal distributed web reinforcement, and concrete compressive strength were the primary variables in the experiments. The results showed that after exposure to fire, ultimate capacity of the members decreases; and no changes occur in the initial stiffness of the members. Furthermore, the failure mode of specimens becomes more brittle and less ductile. Additionally, increasing a/d results in a decrease in the load bearing capacity and a shift in failure mode from pure shear to more ductile modes. By comparing the crack widths at failure point, obtained from image processing, it was found that in the beams with the small a/d ratio which are more shear dominant, after fire exposure, the maximum width of the cracks decreases.