Life-cycle multi-objective optimization design method of RC structures based on sustainability

In order to solve the core problem that the current design methods only focus on short-term performance and can hardly meet the requirements of sustainable development, a life-cycle multi-objective optimization design method of reinforced concrete (RC) structures was proposed based on sustainability. This method considered the cumulative failure probability, economic cost, environmental cost and social cost of RC structures under the influence of marine chlorides, and the optimization objective functions of time-varying reliability index and life-cycle sustainability cost were proposed. Then, the initial design parameters and maintenance parameters of the RC box girder with single objective, double objectives and triple objectives were optimized using Monte Carlo simulation and genetic algorithm. The results show that, compared with the original design scheme, the jointly optimized scheme of parameters during the construction and opera1tion periods improves the initial performance of the structure, enhances the single maintenance effect and reduces the number of subsequent maintenances, thus reducing the social cost and achieving a better sustainability performance under the condition of no significant increase in economic and environmental costs. Moreover, the triple objective optimization method of life cycle economic, environmental and social costs is a feasible approach to balance the three dimensions (economic, environmental and social) of sustainability. The environmental cost is negatively correlated with the economic cost and the social cost, and the economic cost is positively correlated with the social cost, when only the maintenance parameters of bonded steel plates are optimized. © 2023 Science Press. All rights reserved.