An optimum strengthening strategy for corrosion-affected reinforced concrete structures

Corrosion of reinforcing steel in concrete is the most predominant cause for deterioration of reinforced concrete structures, leading to many premature structural failures. To ensure the safety and serviceability of deteriorated structures, a risk-informed and cost-effective rehabilitation strategy is essential. The intention of the present paper is to develop an optimal strengthening strategy for corrosion-affected reinforced concrete structures strengthened with a widely used fiber-reinforced polymer (FRP) technique. In this strategy, the optimum strengthening time and the degree of strengthening-that is, the number of FRP layers-can be determined. Mathematical formulation of the proposed strategy, which is based on cost optimization, is provided in a generic format. Application of the proposed methodology is presented in a numerical example for a corrosion-affected reinforced concrete girder flexurally strengthened with FRP. The Genetic Algorithm (GA) method is used for finding the optimum solution. It is found in the paper that the proposed strategy can determine the optimum strengthening time and amount of FRP strengthening efficiently. It is also found that the ratio of cost of failure to cost of preventive maintenance governs the optimum time for maintenance action. The paper concludes that the developed strategy can assist structural engineers and asset managers in developing rehabilitation or replacement strategy for deteriorated infrastructure. .