Stress-strain relationships

A total of 5 full-scale Reinforced Concrete (RC) frames were tested to develop new models for predicting the structural behavior of corroded RC frames and to verify the accuracy of the models mostly developed for RC columns. Four corroded and one non-corroded RC frame were tested under cyclic loading. Corroded RC frames were tested under displacement-controlled cyclic loading at four corrosion levels and for a constant applied axial load ratio of 0.20, with the same concrete compression strength level and reinforcement bar layout. Actual corrosion ratios were obtained following the loading tests, breaking all RC columns and beams and extracting all reinforcement bars from concrete. The test results demonstrated that the corrosion level played an active role in the structural capacity of the RC frames. Initial corrosion crack widths had more significant effects on structural performance. Some models proposed for corroded RC columns can also be used for corroded RC frames in terms of yield and ultimate load capacities according to the corrosion levels of the columns and beam composing the RC frame. It was also concluded from the test results that the displacement-based ductility ratio for corroded RC frames could still be misleading if they were not computed according to energy-based or bilateral failure criteria. Structural properties such as initial/secant stiffness and energy absorption capacity calculated based on experimental measurements for RC frames had further disclosed corrosion effects