This paper investigates the time-dependent reliability of recycled aggregate concrete (RAC) beams made with 50% incorporation of recycled coarse aggregates. A basic method based on the series system model is adopted to calculate the reliability index, and the case studies show that the reliability index decreases with the service time: the reliability indices decrease from the values of 3.27 and 3.70 to 3.02 and 3.55 for RAC beams and normal aggregate concrete (NAC) beams during the service period of 50 years (target reliability index is 3.2 according to Chinese code) in the first case study, also indicating that the reliability index of RAC beams is lower than that of the NAC beams. Then, influencing factors such as the compressive strength, reinforcement ratio, thickness of concrete cover, carbonation rate and corrosion rate are analyzed based on a parametric study. All these factors affect the time to surface cracking and the time to reach the limit crack width of concrete cover. Finally, this investigation concludes that the methods, such as increasing the compressive strength or appropriately increasing the strength of concrete and reinforcement ratio at the same time, are feasible methods for meeting the requirements of the time-dependent reliability of concrete beams.

本文研究了掺入50％的再生粗骨料制成的再生骨料混凝土（RAC）梁的时变可靠性。采用了基于串联系统模型的基本方法来计算可靠性指标，案例研究表明，可靠性指标随着使用时间的延长而降低：RAC梁的可靠性指标从3.27和3.70降低到3.02和3.55在第一个案例研究中，使用50年的普通骨料混凝土（NAC）梁（根据中文规范，目标可靠度指标为3.2），也表明RAC梁的可靠性指标低于NAC梁。然后，影响抗压强度，配筋率，混凝土表皮厚度，碳化率和抗拉强度等因素。基于参数研究分析腐蚀速率。所有这些因素都会影响表面开裂的时间以及达到混凝土保护层极限裂缝宽度的时间。最后，本研究得出结论，同时增加抗压强度或适当增加混凝土强度和配筋率等方法是满足混凝土梁随时间变化的可靠性的可行方法。