某钢桁架人行天桥现场检测与安全性评定

Detecting and Safety Evaluation of Steel Truss of a Certain Footbridge

目的为确保某钢桁架人行天桥的安全运营,对其进行检测及安全性评估,以判定该桥的实际工作状态.方法对天桥进行外观检查及技术状况评定,设计静载试验加载方案,包括测点布置和荷载工况,此后进行了试验荷载下的桥梁上部结构有限元建模计算.此外还对天桥进行了动载试验.结果人行天桥实荷加载试验的挠度校验系数η值大部分小于1.0,大部分测点的实测挠度值小于理论计算值.天桥主跨上部结构的极限承载力为6.37 kN/m2,与规范中设计用荷载3.85 kN/m2相比偏大.结论基于安全性评估得出该桥结构合理,整体性好,具有一定的安全储备,但其极限承载力相对规范设计荷载偏大,设计偏保守.

With the purpose of ensuring operational safety of the footbridge, some work of inspection, identi- fication and evaluation was taken on it to appraise the actual working conditions of the footbridge. Firstly in- specting is proceeded to evaluate the technical conditions of the bridge. Then designing loading test, inclu- ding measure point disposal and loading scenarios. After that, a FEA of the upper structure of the bridge un- der testing load was carded out. What＇s more a dynamic loading test was executed. Most of the values of the deflection calibration coefficient η of the loading test were less than 1.0, and the measured deflection value was less than the calculated value in most points. The ultimate bearing capacity of the upper structure of the bridge is 6. 37 kN/m2, and it is larger than standardized design load 3.85 kN/m2. On a basis of previous a safety appraisal of the bridge is drawn that the bridge has reasonable structure, good integrity, and some safe- ty margin, but its ultimate bearing capacity is larger than standardized design load so that this bridge was de- signed sparingly.