Effects of Stirrup Corrosion on the Shear Performance of Reinforced Concrete Beams after Fire Exposure

Abstract

Previous studies have demonstrated that elevated temperatures exert a significant influence on the structural performance of reinforced concrete (RC) members. However, the residual shear performance of the RC beam under the combined effects of stirrup corrosion and fire has not been thoroughly explored. Therefore, this paper aims to investigate this aspect by prefabricating eight RC beams and employing experimental, numerical, and theoretical methods. The influence of varying stirrup corrosion degrees and fire exposure time on the residual shear capacity of these beams was examined. It was observed that corrosion-induced cracks had an impact on the distribution of the temperature field within the RC beams. Furthermore, the exposure to the corrosion–fire combination significantly affected the shear capacity of the RC beams. Notably, stirrup corrosion may lead to a more brittle failure after a fire. To assess the impact of corrosion degree and fire exposure time on the temperature field and residual shear properties of RC beams, a simplified finite element (FE) model considering the effect of concrete spalling was developed. The accuracy of this model was validated through a comparison with experimental results. Finally, three theoretical methods for predicting the residual shear capacity of postfire RC beams with corroded stirrups were proposed, based on Chinese, American, and European codes. A comparison between the calculated and test results revealed a good agreement. These methods can provide conservative predictions for practical engineering applications.