模糊失效准则下桥梁拉索锈蚀时变可靠性分析  

Analysis on Time-varying Reliability of Corroded Bridge Cables Based on Fuzzy Failure Criterion

作　　者：王天鹏 张建仁[1] 王磊 马亚飞 WANG Tian-peng;ZHANG Jian-ren;WANG Lei;MA Ya-fei(School of Civil Engineering,Changsha University of Science&Technology,Changsha Hunan 410114,China;School of Civil Engineering,Central South University of Forestry and Technology,Changsha Hunan 410004,China)

机构地区：[1]长沙理工大学土木工程学院,湖南长沙410114 [2]中南林业科技大学土木工程学院,湖南长沙410004

出　　处：《公路交通科技》2021年第8期59-66,共8页Journal of Highway and Transportation Research and Development

基　　金：国家重点基础研究发展计划"九七三"项目(2015CB057705);国家自然科学基金项目(51478050,51778068)。

摘　　要：针对桥梁缆索耐久性问题日益突出的现状,对锈蚀拉索的时变可靠性问题进行了研究。首先,基于不同气候条件下钢丝的腐蚀速率和拉索截面锈蚀扩展规律,由随机过程理论建立了锈蚀拉索的抗力退化模型。针对拉索运营期失效具有模糊性的特点,以安全系数为判据构造了拉索模糊失效的隶属函数,提出了模糊失效准则下拉索锈蚀可靠度分析模型,并采用将服役期离散化的方法简化了时变可靠度的计算问题。通过算例分析了不同腐蚀环境下服役拉索的时变可靠度,并与时不变可靠度以及清晰失效准则下的时变可靠度进行了比较。结果表明:本研究模型能够反映拉索在不同腐蚀环境、不同服役时间内可靠度的变化规律。与清晰失效准则相比,模糊失效准则下时变可靠指标的渐变规律更好,与工程实际更为相符,一定程度上避免了清晰失效准则下安全系数选取困难的情况。拉索服役期的时变可靠指标具有明显的时段区分,当护套完好时,可靠指标下降缓慢,一旦护套破损引发钢丝锈蚀,随着腐蚀环境的不同可靠指标将显著下降。对于护套发生局部破损的拉索,在较恶劣环境中服役寿命仅为8~10 a,由于钢丝锈蚀的不可逆性,避免护套的损伤并加强检测是保证拉索耐久性的关键。In view of the increasingly prominent problem of bridge cable durability,the time-varying reliability of corroded is studied.First,based on the corrosion rate of steel wires and the corrosion propagation rule of cable section under different climatic conditions,the resistance degradation model of corroded cables is established by stochastic process theory.In view of the fuzziness of cable failure in operation period,the membership function of cable fuzzy failure is constructed based on safety factor.The reliability analysis model of cable corrosion under fuzzy failure criterion is proposed,and the calculation of time-varying reliability is simplified by discretizing service period.The time-varying reliability of cables in different corrosive environments is analyzed by examples,which is compared with time-invariant reliability and the time-varying reliability under clear failure criteria.The result shows that(1)The model can reflect the variation of cable reliability in different corrosion environments and service periods.(2)Compared with the clear failure criterion,the gradual change rule of the time-varying reliability indicator under fuzzy failure criterion is better,which is more consistent with the engineering practice,and the difficulty of selecting the safety factor under the clear failure criterion is avoided to a certain extent.(3)The time-varying reliability indicator of cable service life has obvious time division.When the sheath is intact,the reliability indicator decreases slowly.Once the sheath is damaged and the steel wires are corroded,the reliability indicator will decrease significantly with the change of corrosive environment.For the cables with partial damaged sheath,the service life is only 8 to 10 years in harsh environments.Due to the irreversibility of steel wire corrosion,avoiding damage to the sheath and strengthening detection are the keys to ensuring cable durability.

关 键 词：桥梁工程 时变可靠性 模糊失效准则 拉索 锈蚀 

分 类 号：U443.38[建筑科学—桥梁与隧道工程]