Investigation of corrosion of steel stirrups in reinforced concrete structures

Although extensive research on steel corrosion in concrete has been undertaken it is more on longitudinal reinforcing bars than stirrups as suggested in the review of published literature. The effect of corrosion of steel stirrups on structural behaviour can be significant for shear failure mode. This paper aims to investigate the degradation of mechanical behaviour of corroded stirrups. Details of a comprehensive experiment designed to examine the mechanical behaviour of corroded stirrups in concrete structural members are presented. A micromechanical damage model for failure mechanism of corroded stirrups is proposed and a model for damage factor is derived. Based on these models, a constitutive model for corroded stirrups is developed and verified with test results. It is found in the experiment that both the strength and ductility of corroded stirrups decrease with the increase of corrosion and that the hemispherical model for the pit shape is more appropriate for the prediction of strength reduction of corroded stirrups. The constitutive model developed in the paper can be used to predict the mechanical behaviour of corroded stirrups with reasonable accuracy, paving the way for the assessment of corrosion induced shear failure of reinforced concrete structures.