基于健康监测的重载铁路连续刚构桥活载挠度可靠度评估

Reliability Assessment of Vehicle-induced Deflection of Heavy Haul Railway for Continuous Rigid-frame Bridge Based on Health Monitoring

为评价重载铁路连续刚构桥服役性能,提出了一种基于健康监测的主梁活载挠度可靠度评估方法。通过将活载挠度超限作为主梁竖向刚度不足的失效模型,利用健康监测系统实测挠度数据对某运营期重载铁路连续刚构桥活载挠度进行了可靠度评估。结果表明:串联模型可有效反映主梁各截面活载挠度失效模式之间的关系;主梁各截面活载挠度可靠度指标总体呈对称分布;主跨跨中截面为主梁活载挠度可靠性的控制截面;活载挠度可靠度指标在服役初期下降较快,随着服役时间的延长,可靠度指标下降速率趋于稳定;经过体外索加固后,桥梁服役时间为100年的活载挠度可靠度指标上界和下界分别上升了5.21%、5.23%;加固后,桥梁服役时间为160年时,桥梁活载挠度可靠度指标仍大于目标可靠度。可见所提出的方法可以有效评估重载铁路在役连续刚构桥服役性能可靠性。

In order to evaluate the service performance of continuous rigid-frame bridge on heavy haul railway,a reliability assessment method of vehicle-induced deflection of main girder based on health monitoring was proposed.Firstly,vehicle-induced deflection overrun was considered as the failure model for insufficient vertical stiffness of girder.Then,the reliability of vehicle-induced deflection for a continuous rigid-frame bridge on heavy haul railway was evaluated,based on the measured deflection data of health monitoring system.The results show that the relationship between vehicle-induced deflection failure modes of each girder section can be effectively reflected by the series model.The vehicle-induced deflection reliability of each girder section is symmetrically distributed.The 1/2 section of main span is the control section for vehicle-induced deflection reliability.The reliability decreases rapidly in the early stage of service,but the decline rate tends to be stable with the increase of service time.The upper boundary and lower boundary of reliability indices for bridge service time of 100 years increases by 5.21%and 5.23%due to external cable reinforcement.Even if the service time of the bridge reaches 160 years,the reliability index of vehicle-induced deflection is still higher than the target reliability.It is concluded that the method proposed can effectively evaluate the reliability of service performance of the continuous rigid-frame bridge on heavy haul railway.