Development Methodology of Determinating Residual Carrying Capacity of Reinforced Concrete Beams with Damages Tensile Reinforcement Which Occurred during Loading

This paper reports the improved and verified procedure for calculating reinforced concrete beams affected by damage to stretched reinforcement when loaded. The main results from testing the reinforced concrete beams with damage in the stretched zone in the form of one hole in the reinforcement in the middle of the beam are given. The variable parameter of the study was the level of load resulting in the damage. It acquired values of 0, 30 %, 50 %, 70 % of the bearing capacity of control undamaged samples. Overall, the results of testing 12 samples are given. A new procedure has been proposed for taking into consideration changes in the mechanical characteristics of stretched reinforcement arising from its damage. This makes it possible to more accurately establish the bearing capacity of reinforced concrete bended elements affected by damage to their reinforcement during operation. The analysis of the calculation, compared with experimental quantities, led to a conclusion that the strain model could determine when the bearing capacity of reinforced concrete beams without damage and with damage to working reinforcement is exhausted. Based on the improved algorithm, the principle of using a strain model was proposed to establish when the bearing capacity of damaged samples, taking into consideration the effect of the load level, is exhausted. The theoretical estimation, considering when the bearing capacity is exhausted, showed results that are 3...21 % less than the experimental values, which ensures reliability of calculation of such structures. The proposed calculation provides a new approach to determining the bearing capacity of reinforced concrete beams damaged during operation. That, in turn, makes it possible to more accurately determine the residual bearing capacity of structures and increases the safety of their operation.