大气环境下服役公路梁桥结构时变可靠度分析

为了准确评估钢筋锈蚀对大气环境下服役桥梁耐久性能影响,结合一般大气环境下钢筋锈蚀的系统研究成果和服役桥梁实际检测资料,综合考虑钢筋截面面积、屈服强度和黏结强度的降低,建立服役公路桥梁弯曲抗力退化时变模型,在现有运营荷载等级和服役周期基础上分析结构时变可靠度.针对一座实际服役桥梁开展分析,计算表明：在一般大气环境下综合考虑钢筋锈蚀对钢筋截面面积、屈服强度和黏结退化的影响,桥梁结构时变可靠度在31 a左右即下降到需要维修补强的程度,与工程实际的首次维修维修时间基本一致,远远提前于只考虑钢筋截面面积单因素简化模型预测时间.多因素模型预测的桥梁结构时变失效风险较其他模型明显增大,同时在各个蜕化因素中,黏结退化对结构承载力降低有显著影响.

Time-dependent reliability analysis of existing bridges under atmospheric environment

In order to accurately evaluate the existing bridges durability performance under atmospheric corrosion,the research achievements related to rebar corrosion were integrated and combined with field measurement of existing bridges.A multi-factor time-dependent resistance model of bridge bending capacity was established with degradation in rebar area,yield strength and bonding considered.The system reliability was investigated based on practical current live load level and service time.The case study of one real existing bridge shows that the initial maintenance time predicted by multi-factor model is 31 years,which is consistent with the bridge management situation,that is earlier than the single-factor model prediction.The failure risk predicted from multi-factors model is obviously higher than that gotten from other models.The bonding degradation should be the significant factor in the bridge durability analysis.