Evaluation of reinforced concrete (RC) structures which are subjected to the damaging environmental factors during the service life is critical. The service life model, the effects of environmental factors with their extent of damage during the service period of the structure could be predicted. Various uncertainties that came with this assessment confidence in the results should be taken by a safe margin. Structural reliability methods are one of the best tools to calculate the life model that considers the random properties of parameters. However, if the epistemic and inherent uncertainty of parameters with their time-dependent changes considered, the life model is more reliable. The reinforcement corrosion is the most damaging mechanism that causes the premature degradation of RC structures and substantial economic losses each year. In this work, the time-dependent reliability of an RC beam with chloride-induced corrosion considering epistemic uncertainty via an efficient numerical procedure is developed. Fuzzy time-dependent reliability index has been calculated using $\alpha$-cut approach based on a hybrid version of genetic algorithm (GA) and particle swarm optimization (PSO), namely HGAPSO applying three-term conjugate reliability method. Results showed that the proposed numerical approach could efficiently and robustly estimate the fuzzy time-dependent reliability index.

评估使用寿命期间受破坏性环境因素影响的钢筋混凝土（RC）结构至关重要。可以预测使用寿命模型，环境因素的影响及其在结构使用期内的损坏程度。评估信心对结果带来的各种不确定性应有一定的把握。结构可靠性方法是计算考虑参数随机属性的寿命模型的最佳工具之一。但是，如果考虑参数的认知和固有不确定性及其随时间的变化，则寿命模型将更可靠。钢筋腐蚀是破坏力最大的机制，每年都会导致RC结构过早退化和大量经济损失。在这项工作中，通过有效的数值程序，开发了考虑到不确定性的氯离子腐蚀的钢筋混凝土梁的时变可靠性。模糊时间相关的可靠性指标已使用$\alpha$遗传算法（GA）和粒子群优化（PSO）的混合版本的多切方法，即应用三项共轭可靠性方法的HGAPSO。结果表明，所提出的数值方法可以有效，鲁棒地估计模糊的时变可靠性指标。