考虑非平稳过程的劣化钢筋混凝土梁桥时变可靠度分析  

Time-dependent reliability analysis of deteriorating reinforced concrete bridges considering nonstationary processes

作　　者：金聪鹤 钱永久[1] 张方[1] 徐望喜 JIN Cong-he;QIAN Yong-jiu;ZHANG Fang;XU Wang-xi(School of Civil Engineering,Southwest Jiaotong University,Chengdu 610031,China)

机构地区：[1]西南交通大学土木工程学院,成都610031

出　　处：《工程科学学报》2022年第7期1265-1273,共9页Chinese Journal of Engineering

基　　金：国家自然科学基金资助项目(51778532)。

摘　　要：采用Gamma随机过程描述车辆荷载频率函数,提出了基于荷载频率增大的钢筋混凝土桥梁时变可靠度分析方法.考虑历史荷载信息对桥梁时变抗力的验证作用,改进了抗力变异系数为时间变量的桥梁时变可靠度计算公式.采用上述方法,对某装配式预应力混凝土桥进行时变可靠度分析,结果表明,车辆荷载频率增量关联与否不影响结构时变可靠度的变化;结构在20至40 a的时变失效概率介于验证荷载为31.6%至36.4%初始抗力的失效概率之间,证明改进的公式具有更高的精度.当荷载频率λ小于10 a^(−1),考察范围不超过35 a,若历史荷载强度不高于初始抗力的29.1%,可以采用基于荷载频率函数λ(t)的可靠度计算方法;若一年两遇的车载强度超过结构初始抗力的36.4%,且年均增长率γ超过150%时,在海洋环境建造的钢筋混凝土梁桥在20 a内的失效概率较高,需引起注意,在设计和施工时增强钢筋的耐锈蚀性.Traffic volume and vehicle loads are increasing with time during the bridge service life.Time-dependent reliability theory considers the time-varying effects of loads and resistance,which has been commonly adopted in recent engineering reliability research.The degradation of bridge resistance and increase of vehicle load and frequency varies with time,as described by a nonstationary stochastic model.The gamma stochastic process is adopted to describe the frequency function of vehicle load occurrence to promote the application of nonstationary processes in reliability studies,and time-dependent reliability analyzing approach is proposed for reinforced concrete bridges based on increasing load frequency.The time-dependent reliability equation is modified to account for the verifying effect of historical load information on time-varying resistance by including the coefficient of variation of bridge resistance as a time-associated variable.The above two methods are then used to perform a time-dependent reliability analysis on a prefabricated prestressed concrete bridge.The results show that the structural time-dependent reliability immunes the correlativity of frequency increment of vehicle loads;the time-dependent failure probabilities within 20 to 40 years range from those obtained by proof load tests with load intensities between 31.6%and 36.4%of the initial resistance,indicating higher precision of the modified equation.When the load frequencyλis less than ten times a year,the inspecting time interval is within 35 years,and the historical load intensity is less than 29.1%of the initial resistance,the approach based on load frequency functionλ(t)is available.When the load frequency exceeds 36.4%of the bridge’s initial resistance,and the annual growth rate of frequency(γ)exceeds 150%.The RC bridge structure constructed in the marine environment has a higher failure probability within 20 years;thus,extra attention must be paid as corrosion resistance of reinforcements should be enhanced during its design and co

关 键 词：时变可靠度 非平稳随机过程 历史荷载信息 频率函数 伽马分布 钢筋混凝土梁 

分 类 号：U441.2[建筑科学—桥梁与隧道工程]