Life Cycle Cost GA Optimization of Repaired Reinforced Concrete Structures Located in a Marine Environment

Abstract

Life-Cycle-Cost (LCC) analysis of corroded structures located in corrosive marine environments considers the time-dependent resistance and loading affect, and repair and maintenance scenarios applied during life time of these structures. Finding the optimum repair and maintenance scenario for a corroded reinforced concrete (RC) structure is a significant process to select a repair and maintenance scenario with minimum LCC and maximum service lifetime. For this purpose, a finite element (FE) model is applied to assess the time-dependent capacity of corroded RC circular column using nonlinear analysis. In corrosion initiation phase, empirical chloride diffusion and surface chloride concentration models obtained for silica fume RC under long-term exposure in splash zone of Bandar-Abbas coasts, located in south side of Iran, and in corrosion propagation phase, empirical corrosion current density model for splash zone of a marine environment in literature is used for modeling of corrosion process. In this analysis, the influence of a number of repair or rehabilitation scenarios on the performance of a corroded circular RC column due to chloride-induced corrosion, including five different concrete surface coatings used on the external surface of concrete, four different increasing concrete cover thickness and using the new longitudinal and horizontal reinforcements after the initial cracking of concrete cover are investigated. These 11 different scenarios with considering a scenario without any repair are optimized by Genetic Algorithm (GA) based on minimum LCC cost and 40 years failure time in terms of corrosion.