老龄桁架桥的检测评估方法

Inspection and Evaluation Method for Old Steel Truss Bridges

由于现有规范采用的钢桁架桥的检测与评估方法无法满足结构承载力与剩余寿命评估的需要,结合上海市外白渡桥研究一种适用于老龄钢桁架桥的检测与评估方法。首先依据交通调查资料,采用Monte-Carlo法建立交通荷载模型,得出结构的最大内力与疲劳应力谱;然后切取实桥锈蚀构件进行试验,分析锈蚀对结构承载力的影响规律,根据量化的锈蚀程度检测结果计算构件的剩余承载力;最后采用基于断裂力学理论的损伤容限计算方法分析桥梁的剩余使用寿命。对外白渡桥的分析结果表明:该桥有40根杆件、4个节点板的承载力及8个构件的剩余寿命无法满足继续使用的要求。

As the inspection and evaluation methods for steel truss bridges adopted in the current codes and specifications can not cater for the need of evaluation of the structural carrying capacity and remaining life, a method suitable for the inspection and evaluation of old steel truss bridges was developed on the basis of research of the Waibaidu Bridge in Shanghai City. In the method, the traffic load model was firstly established by the Monte-Carlo method in accordance with the traffic survey data and the maximum structural internal force and fatigue stress spectrum were obtained by calculation. The rusted members of an actual bridge were then cut off and sampled for testing, the law of influence of rust corrosion on the structural carrying capacity was analyzed and the remaining carrying capacity of the members was calculated in accordance with the inspection results of quantified rust degrees. Finally, the remaining life of the bridge was analyzed by the calculation method of damage allowance based on the fracture mechanics theory. The results of the analysis of the Waibaidu Bridge by the developed method demonstrated that the carrying capacity of 40 members and 4 panel points and the remaining life of 8 members of the bridge could not meet the requirements of continuous service.