Seismic performance assessment of existing three and seven-storey RC moment frames considering steel reinforcement corrosion

Abstract

Corrosion of steel reinforcement in concrete structures is one of the most influencing factors in the loss of durability of reinforced concrete (RC) structures. Neglecting the effects of corrosion has unpleasant consequences and may lead to the failure of structures before their designed life time. Corrosion reduces the cross section of the steel reinforcement, changes the mechanical properties of the steel, decreases the strength of the concrete, and ultimately reduces the capacity and ductility of RC structures. In this study, the effects of corrosion on the moment-curve diagram of structural elements are studied and then compared with the approaches recommended by guidelines such as FEMA-356. To evaluate the effect of steel corrosion on the performance of structures, two RC frames (3-storey and 7-storey) are modeled and two corrosion scenarios are applied to beams and columns of the structures. Then, capacity curves of structures as well as design parameters such as ductility coefficients are obtained by nonlinear static (pushover) analysis of the structures considering the effects of corrosion on moment-curvature diagrams of structural elements. The results show that the coefficient of awareness of 0.75 according to the guidelines such as FEMA-356 can lead to overestimate the structural capacity in highly corrosive environment. It also leads to conservative and uneconomic results in a low corrosive environment. It is observed that the capacities of the 3 and 7-storey structures have been decreased between 19 to 36 percent due to corrosion. Results also show that corrosion reduces the structural capacity between 8 to 28 percent.