考虑混凝土强度随机退化的长寿命斜拉桥主梁目标可靠指标确定方法  

A Method for Determining the Target Reliability for Long Life Cable-stayed Bridges Considering Random Degradation of Concrete Strength

作　　者：张振浩 田勇 梁高明 ZHANG Zhen-hao;TIAN Yong;LIANG Gao-ming(School of Civil Engineering,Changsha University of Science&Technology,Changsha 410114,Hunan,China;College of Mechanical and Electrical Engineering,Xiangxi National Vocational and Technical College,Xiangxi 416000,Hunan,China)

机构地区：[1]长沙理工大学土木工程学院,湖南长沙410114 [2]湘西民族职业技术学院机电工程学院,湖南湘西416000

出　　处：《中国公路学报》2025年第1期199-212,共14页China Journal of Highway and Transport

基　　金：国家重点研发计划项目(2021YFB2600900);湖南省人才托举工程项目(2023TJ-Z17);湖南省教育厅科学研究项目(重点项目22A0239);长沙市自然科学基金项目(kq2202210)。

摘　　要：针对混凝土斜拉桥长寿命设计时的材料参数取值以及PC主梁构件目标可靠指标取值问题,对混凝土强度的随机退化规律、考虑设计使用年限的材料参数取值方法、斜拉桥PC主梁构件考虑材料性能退化的目标可靠指标确定方法进行了研究。首先,基于相关实测数据,对冻融循环下混凝土抗压强度退化过程进行随机过程辨识,结果表明冻融循环下混凝土强度退化规律基本符合Gamma过程,并建立了Gamma过程辨识方法。其次,提出了一种考虑设计使用年限确定所需的材料性能值的方法。基于混凝土抗压强度退化基本服从Gamma过程的结论,获得混凝土性能退化过程在任意时间处的一维概率分布,根据其概率密度函数以α′=0.05分位值确定结构服役至设计使用年限时的混凝土强度退化量,从而确定能满足设计使用年限要求的混凝土抗压强度设计值。最后,在考虑混凝土强度退化及钢筋锈蚀、钢筋与混凝土协同工作能力退化的情况下计算斜拉桥PC主梁时变抗弯承载力;运用验算点法计算斜拉桥PC主梁的时变可靠指标,基于服役期可靠指标的退化量,建立了结构长寿命设计条件下考虑设计使用年限的斜拉桥PC主梁目标可靠指标确定方法。研究可为斜拉桥目标可靠指标合理定值提供参考。This study investigated the material parameter values for the long-life design of concrete cable-stayed bridges and target reliability index values for PC main beam components.In addition,it investigated the random degradation law of concrete strength,a method for determining material parameter values considering the design service life,and a calculation method for the target reliability index considering the material performance degradation of cable-stayed bridge PC main beam components.First,based on relevant measured data,a random process identification of concrete compressive strength degradation under freeze-thaw cycles was conducted.The results show that the degradation law of concrete strength under freeze-thaw cycles followed the Gamma process,and a Gamma process identification method was established.Second,a method was proposed to determine the required material performance values by considering the design service life.Based on the conclusion that the degradation of the concrete compressive strength follows the Gamma process,a one-dimensional probability distribution of the concrete performance degradation process at any time was obtained.The concrete compressive strength design value that meets the requirements of the design service life was determined based on the probability density function withα'=0.05 percentile value when the structure is in service until the design service life.Finally,the time-varying flexural bearing capacity of the cable-stayed bridge PC main beam was calculated by considering the degradation of concrete strength,rebar corrosion,and collaborative working capacity degradation of the rebar and concrete.The time-varying reliability index of a cable-stayed bridge PC main beam was calculated using the checkpoint method.Based on the degradation of the service period reliability index,a method was established to determine the target reliability index of the cable-stayed bridge PC main beam,considering the design service life under the condition of a long-life design.This study provid

关 键 词：桥梁工程 斜拉桥 长寿命设计 性能随机退化 Gamma过程 材料参数设计值 目标可靠指标 

分 类 号：U441[建筑科学—桥梁与隧道工程]