RESEARCH ON THE CALCULATION METHOD OF SHORT-TERM BENDING CRACK WIDTH AND STIFFNESS OF CORRODED REINFORCED CONCRETE BEAMS UNDER DIFFERENT COOLING METHODS

To investigate the ultimate limit state of corroded reinforced concrete (RC) beams under different cooling methods, 20 concrete beams were fabricated. They were subjected to accelerated corrosion tests, fire tests, and static tests after natural cooling and water spray cooling. The study found that with increasing damage, the stiffness and deformation capacity of the test beams were reduced. For example, with a corrosion rate of 0.15 and a fire time of 120 min, the stiffness of the test beams decreased by 63.6% under water spray cooling, which was more significant compared to the 56.9% reduction under natural cooling; in addition, the width of the bending cracks in the corroded beams was 1.5-2.2 times larger than that of the intact ordinary concrete beams. Based on the “Code for Design of Concrete Structures GB50010-2010”, it was found that the error between the calculated and measured deflection values was large and the calculation was conservative. Therefore, a correction was made, and formulas for short-term stiffness and crack width of corroded beams under different cooling methods were established. The results were verified using experimental data from this study and existing literature. The results show that the average ratio of calculated values to experimental values is 0.97 and 1.028, which are in good agreement and the calculation is relatively safe.