Residual behaviour of corroded reinforcements after high temperature exposure

Abstract

Accidental fires in aged concrete structures may lead to a combination of corrosion and fire. Assessing the structural performance of aged concrete after fire exposure is critical for life and property safety. Considering the effect of high temperatures and corrosion on the residual mechanical properties of reinforcement, accelerated corrosion tests, high-temperature tests, and static tension testing were conducted. The results indicated that the fracture source of the regular rebar is usually located at the center of the fracture surface; however, it moves to the corrosion pits for the corroded rebar. Compared with a corroded reinforcement unexposed to high temperature, the load capacity of rebars exposed to high temperatures decreased significantly, which was more prominent when the temperature was above 600 °C. Moreover, after experiencing high temperatures, the degradation rate for the load capacity of the corroded hot-rolled ribbed bars was higher than that of the corroded hot-rolled plain bars. Compare with ultimate load and strain, the energy absorption capacity drops more severely with increasing corrosion degree. Regarding the yield and ultimate strength based on the mean cross-sectional area, corrosion accelerated the strength degradation of hot-rolled ribbed bars after heat treatment, whereas the strength of heated hot-rolled plain bars was less affected by corrosion. The findings and conclusions of this study can provide a theoretical basis for evaluating the fire-induced damage in corroded concrete structures.