Experimental and numerical study on post-fire flexural capacity of corroded reinforced concrete beams under various cooling methods

This paper investigates the flexural behavior of corroded reinforced concrete (RC) beams after various cooling methods. Twenty-eight RC beams were fabricated, with four beams remaining unexposed to fire and twenty-four subjected to fire damage. The study examined three concrete cover thicknesses (20 mm, 30 mm, and 40 mm), three fire exposure times (60 min, 90 min, and 120 min), and two cooling methods (natural cooling and water cooling) to analyze their impacts on the flexural properties of corroded RC beams. The results revealed that the minimum temperatures experienced by the steel bars were observed with a concrete cover thickness of 40 mm, indicating a reduction of up to 18.19 % compared to a cover thickness of 20 mm. After a 120 min fire exposure, water cooling resulted in brittle failure of corroded RC beams. Relative to room temperature, the peak load of non-corroded specimens with a 20 mm concrete cover thickness decreased by 18.2 % and 26.6 % at 90 and 120 min, respectively. For fire exposure durations of 60, 90, and 120 min, water spraying cooling resulted in a reduction of the peak load of corroded RC beams with a 20 mm cover thickness by approximately - 3.9 %, 4.7 %, and 18.9 %, respectively, compared to natural cooling. After 120 min of fire exposure, the bearing capacity of water-cooled specimens increased with increasing concrete cover thickness. Numerical simulations utilizing the finite element method were employed to analyze the thermal response and flexural properties of corroded RC beams. The residual flexural capacity of corroded RC beams post high-temperature exposure was evaluated using three design codes: GB 50010-2010, ACI 318-19, and EN 1992-1-1.