FRP箍筋强度保留率分布模型与可靠性分析

Strength Retention Rate Distribution Model and Reliability Analysis of FRP Stirrups

基于文献数据,采用假设检验法,开展纤维增强复合材料(FRP)箍筋强度保留率分布规律研究.通过Kolmogorov-Smirnov(K-S)检验对比了Weibull分布、正态分布及对数正态分布这3种模型对FRP箍筋强度保留率的拟合优度.结果表明:当FRP箍筋弯折半径(R)与箍筋直径(D)之比(R/D)在常规范围内(3~5)时,对数正态分布为最优分布模型,据此得到95%和50%保证率下FRP箍筋强度保留率分别不小于32.46%和43.79%;中国、美国、日本和加拿大四国规范保留率预测公式计算结果的保证率仅为24.1%~40.3%,偏于不安全.根据中国FRP纵筋与箍筋的强度保证率要求,当R/D=3、4、5时玻璃纤维增强复合材料(GFRP)箍筋强度保留率不小于38.86%、35.68%、46.09%.

The hypothesis testing approach was applied to treat the experimental data from the open literature for the establishment of the distribution law of the strength retention rate of fiber reinforced plastic(FRP)stirrups.The goodness-of-fit of three distribution models(Weibull distribution,normal distribution,and lognormal distribution)for the FRP stirrups strength retention rate was compared using Kolmogorov-Smirnov(K-S)test.The results show that the lognormal distribution is the optimal distribution model within the rational range(3-5)of internal radius(R)to bar diameter(D)ratio(R/D).It follows that the strength retention rates of 95%and 50%guarantee rates is no less than 32.46%and 43.79%,respectively.Furthermore,the results show that the reliabilities of calculation results from the retention rate formula used in the Chinese,American,Canadian,and Japanese standards are only between 24.1%-40.3%,which is unconservative.According to the strength guarantee rate requirements of FRP longitudinal reinforcement and stirrups in China,the strength retention rates of glass fiber reinforced plastic(GFRP)stirrups with R/D of 3,4 and 5 are not less than 38.86%,35.68%and 46.09%,respectively.