基于支持向量机法的混凝土强度对拼宽T梁桥时变可靠度影响分析

Influence Analysis of Concrete Strength on Time-Varying Reliability of Widening T-Beam Bridge Based on Support Vector Method

基于支持向量机法,研究了拼宽T梁桥的效应函数在小样本条件下的隐式函数拟合精度问题,误差小于5%;将拟合的隐式函数用于构建正截面抗弯承载力功能函数,分析了拼宽桥的时变可靠度变化规律。研究结果表明:SVM法预测结果偏小;分析强度时变效应及收缩徐变因素,在70 a内梁片结构可靠指标降低速率及幅度不显著,且较不分析时变效应时高;假设旧梁运营20 a后进行拓宽,新梁运营45 a内,拼宽桥体系可靠指标降低速率相对平缓;新梁运营45 a后,拼宽桥体系可靠指标减少则值得关注。

Based on support vector method,the fitting accuracy of implicit function for the effect function of widening T-beam bridge under the condition of small sample was studied,whose error was less than 5%.The fitting implicit function was used to construct the function of flexural capacity of normal section,and the variation law of time-varying reliability of widening T-beam bridge was analyzed.The research results show that:the prediction results obtained by SVM method are smaller;considering the time-varying effect of concrete strength as well as shrinkage and creep,the reduction of reliability index of beam structure in 70 years is not significant,and it is higher than that of structure without considering time-varying effect.Taking the widening of old beams after 20 years of operation as an example,the reliability index of widening bridge system decreases relatively smoothly in 45 years of operation of new beams,while the reliability index of widening bridge system decreases significantly after 45 years of operation of new beams.