Calculation Method of the Residual Bearing Capacities of Concrete T-Shaped Beams Considering the Effect of Fire Cracks

To obtain an accurate estimation of the residual bearing capacities of concrete T-shaped beams after fire exposure, a calculation method combined the finite element (FE) thermal simulation and analytical equilibrium equation was established on a basis of an experimental study of fire (high-temperature) exposure. The effect of the concrete crack size under fire exposure on the post-fire residual bearing capacity was carefully considered in the calculation method. The influences of the load ratio, reinforcement ratio, height-to-width ratio and concrete cover thickness on the residual bearing capacity of a concrete beam after fire exposure were studied, and then a calculation formula for predicting the residual bearing capacity of a concrete T-shaped beam considering fire cracks was proposed according to these influencing factors. The results show that the height-to-width ratio and the reinforcement ratio have a great influence on the residual bearing capacity of the T-shaped beam after fire exposure; these ratios are positively correlated with the residual bearing capacity. The load ratio of the T-shaped beam also has a great influence on the residual bearing capacity of the beam after fire exposure; this ratio is negatively correlated with the residual bearing capacity. The thickness of the concrete cover has little effect on the residual bearing capacity. Compared with that of the finite element simulation results, the calculation accuracy of the residual bearing capacity formula after fire exposure is satisfactory; thus, this work can provide a reference for the calculation of the residual bearing capacity of concrete T-shaped beams after fire exposure.