Ultimate and nominal shear strength in reinforced concrete beams deteriorated by corrosion

Abstract

Exposure to aggressive agents such as chlorides facilitates the corrosion process of the transversal reinforcement (stirrups) of concrete beams, as the steel of these reinforcements is closest to the concrete’s surface. Two groups of eight beams each were fabricated, and had a separation of either 150 or 200 mm between stirrups for each series. During the first stage, beams were exposed to wetting cycles using a 3.5% NaCl solution, and were then subjected to a drying process until steel depassivation was reached. Subsequently, a 100 μA/cm 2 printed current was applied for either 80 (moderate) or 120 (severe) days in order to reach different levels of corrosion in the stirrups. Results showed that the ultimate shear strength was influenced mainly by moderate and severe levels of deterioration, as beams subjected to these treatment levels showed a 30% decrease in ultimate shear strength relative to control beams. Additionally, beam ductility was affected by levels of moderate and severe deterioration of stirrups, and this was evident due to the brittleness and sudden failure observed during beam testing. Finally, our findings indicated that the average remaining section based on the critical diameter of the stirrups was a reliable predictor of ultimate shear strength.