Residual strength of corroded reinforced concrete beams.

Currently, much research is focused on the corrosion of reinforcement in concrete members. However, none addresses the problems associated with the residual strength of reinforced concrete beams exhibiting both main and shear reinforcement corrosion simultaneously. The aim of this research, therefore, was to determine the residual strength of corroded reinforced concrete beams where various degrees of reinforcement corrosion is present in both the main and shear reinforcement. This may provide a better understanding of the performance of deteriorated reinforced concrete beams in service.One of the main causes of concrete deterioration is corrosion of the steel reinforcement and thus a reduction of the residual service life. In general, corrosion of reinforcement is believed to affect the structural performance of concrete elements in two ways. Firstly, by reducing the rebar cross sectional area, and secondly, by loss of bond strength between the concrete and steel reinforcement and resulting growth of cracks due to the formation of corrosion products at concrete/reinforcement interface.The experimental programme was carried out to provide information on the loss of strength resulting from corrosion to the main and shear reinforcement. Corrosion was induced by means of external power supplies. The test programme was divided into three series. Series I was devised to determine the residual flexural strength of reinforced concrete beams where different diameters of main (high yield) reinforcement were subjected to varying degrees of accelerated corrosion (shear strength was provided by mild steel shear reinforcement which remained unaffected by corrosion). Series II was devised to determine the residual shear strength of reinforced concrete beams where the shear (mild steel) reinforcement was subjected to varying degrees of accelerated corrosion (flexural strength was provided by high yield steel which was protected from corrosion). Finally, Series III was devised to determine the residual strength of reinforced concrete beams where both the main (high yield) and shear (mild steel) reinforcement were simultaneously corroded and the effect of this on the performance of the beam was determined. In total, 116 beams were subjected to accelerated corrosion using an impressed current imposed on the reinforcement. Each beam was loaded to failure to determine the strength loss. Four degrees of corrosion were targeted, ranging from 0% (control) to 15%, in increments of 5%.The results of the laboratory tests determined the significance of both main and shear reinforcement corrosion on the performance of deteriorated reinforced concrete beams. In addition, simplified analytical equations were developed which may assist the engineer in assessing the residual strength of corroded reinforced concrete beams.