Residual Life Assessment of Reinforced Concrete Considering Tension Softening Behaviour

Abstract

Under fatigue loading, concrete exhibits softening behaviour due to the formation of an inelastic zone ahead of the crack tip. The formation of this inelastic zone is due to the heterogeneities present in the concrete. This inelastic zone is dominated by various toughening mechanisms. Current design practices for reinforced concrete is by assuming a zero tensile strength for concrete which is over conservative. Actually concrete can withstand a reasonable tensile stress and strain. Therefore study of RC member should consider the tension softening response of concrete. Under fatigue loading, strength and stiffness decrease progressively according to the maximum amplitude and the number of cycles. Fracture plays an important role in failure of normally and lightly reinforced beam. Since FPZ mechanisms and fibre bridging action resist crack propagation, we need to consider those while predicting remaining life of RC member. Fatigue failure occurs when applied load is much less than the moment capacity. Such structures susceptible to fatigue load need to be monitored and residual life is to be predicted. This paper aims to predict the residual life of reinforced concrete members are assessed in terms of moment carrying capacity by considering various tension softening laws.