Shear Behavior of Thermally Damaged Reinforced Concrete Beams

Sixteen shear-critical reinforced concrete short beams (RCSB) with different percentages of tension reinforcement were loaded until failure at ambient and after 350, 550, and 750°C temperatures. Elevated temperatures resulted in a higher shear capacity loss in the beams with a lower tension reinforcement. Stiffness of the beams reduced, whereas midspan deflection corresponding to ultimate load increased after elevated temperatures. Load-shear crack width responses indicated a brittle failure in the beams up to a temperature of 350°C. Ductile failure was perceived in the specimens tested after 550 and 750°C. The strains in tension reinforcement corresponding to ultimate load decrease as the exposure temperature increases. Theoretical predictions provided reasonable estimates of shear capacities up to a temperature of 350°C; in contrast, shear capacities of beams exposed to over 550°C were found up to 46% higher. The experimental results were used to develop an equation for the computation of the shear capacity of RCSB after exposure to elevated temperatures.