海洋环境下CFRP加固梁的时变可靠度分析

Time-dependent Reliability Analysis of CFRP-strengthened Reinforced Concrete Beams Subjected to Marine Environment

建立了海洋环境下CFRP加固梁的时变抗力表达式,对影响抗力的相关变量做了统计分析,并根据Monte Carlo-JC法和Monte Carlo法分别编制了计算程序。通过将抗力简化为各时段的随机变量,Monte Carlo-JC法先用Monte Carlo法抽样得到各时段抗力样本值,进而获得抗力统计参数,然后用JC法计算构件的时变可靠度。结果表明,未加固梁的可靠度在开始几年变化不大,第5年后开始迅速下降;在第15年用CFRP加固后,可靠度大幅提高,到第30年仍具备较好的安全性。以Monte Carlo法的计算结果作为精确解,通过对比,证明上述采用的Monte Carlo-JC法是一种高效且偏安全的可靠度计算方法。

The formula for calculating time-varying flexural resistances of CFRP-strengthened reinforced concrete beams in marine environment is developed, accompanied by statistical analysis of some main influencing factors, then Matlab programs are compiled respectively based on Monte Carlo JC method and Monte Carlo method. Through transfor ruing the resistances into time-varying random variables, Monte Carlo-JC method obtains sample values of resistances simulated in Monte Carlo method at first, and statistical parameters can be obtained, then time-dependent reliability is carried out in JC method. According to the results, before the 5th year, reliability of concrete beams doesn＇t change much, then it declines rapidly from then on. In the 15th year, concrete beams are strengthened by CFRP, which im proves the reliability significantly. CFRP-strengthened beams still remain high reliability in the 30th year. Compared with Monte Carlo method, of which the calculation results can be considered as exact solutions, Monte Carlo-JC method is more efficient and safer.