在役公路钢桥可靠性评估方法研究

Study of Reliability Evaluation Method for In-Service Steel Highway Bridges

为构建在役公路钢桥安全评估技术,保证在役桥梁的运营安全,研究分析基于可靠指标和基于分项系数2种可靠性评估方法。依据公路桥梁承载能力检测评定规程中的钢结构桥梁承载能力检算系数和活载影响修正系数,建立在役钢桥劣化状态极限状态方程,利用0.618优化法,得到2种评估方法相应技术参数及指标。研究表明,公路钢桥技术状况可按优、良、中、差、劣和失效6种等级区间划分。基于可靠指标评估方法中,优、良、中、差、劣5种桥梁技术状况,分别对应评估目标可靠指标为4.2、3.8、3.5、3.3和3.0;基于分项系数评估方法中,优、良、中、差、劣5种桥梁技术状况,分别对应抗力分项系数为1.35、1.25、1.2、1.15和1.1。2种评估方法可认为是等效统一的。

To figure out the safety evaluation techniques for in-service steel highway bridges and ensure the operation safety ,two reliability evaluation methods were analyzed ,among which one is based on reliability indexes and the other on partial factors .The limit state equation of the deteriorating condition of in-service bridges was established according to the load bearing capacity checking coefficient and the correction coefficient of live load effect for steel structure bridges in the inspection and evaluation specifications for load bearing capacity of existing bridges .The equa-tion is optimized by the 0 .618 optimization method to gain the relevant technical parameters and in-dexes of the two evaluation methods .The study indicate that the technical condition of steel high-way bridges can be classified into six grade range of “excellent” ,“sound” ,“medium” ,“poor” ,“bad” and “failure” .For the evaluation method based on reliability indexes ,the technical condition of a bridge can be identified as “excellent” ,“sound” ,“medium” ,“poor” ,and “bad” ,and the cor-responding target reliability indexes are 4 .2 ,3 .8 ,3 .5 ,3 .3 and 3 .0 ,respectively .For the evalua-tion method based on partial factors ,the technical condition of a bridge can be identified as “excel-lent” ,“sound” ,“medium” ,“poor” and “bad” ,and the corresponding target reliability indexes are 1 .35 ,1 .25 ,1 .2 ,1 .15 and 1 .1 ,respectively .The two evaluation methods can be regarded as equiv-alent and uniform .