中承式拱桥吊杆专项检测及疲劳寿命评估

摘要

The operation safety of hangers directly influences the structural safety of the arch bridge.A half-through arch bridge built in 1990 was cited as an example to assess the fatigue life of hangers,based on the previous specialist inspection and fatigue life assessment of the hangers of the bridge.The specialist inspection revealed that the anchor heads of most hangers were not tightly sealed,stains of seeped water were found in the anchor sockets and the PE sheaths were damaged and contained cracks.The visual inspection showed that the hangers were not in good condition,the corrosion degree of the steel wires of the short hangers reached the scale value of 4 prescribed in the code,in a very worse condition.The fatigue life of the hangers was predicted ac-cording to the actual traffic volume and fatigue stress amplitude,and the calculated fatigue life of the hangers in the corrosion-free environment was about 44 years.But when corrosion occurs,the service life of the hangers does not even reach 1/5 of that of the corrosion-free hangers,w hich means that the service life of the corroded hangers could not reach 10 years.The inspection conclu-ded that the hangers have potential safety hazard and should be replaced.%吊杆的运营安全直接影响到拱桥的结构安全,以1990年建成的某中承式拱桥为研究对象,结合该桥吊杆专项检测及理论分析结果,对吊杆的疲劳寿命进行评估.专项检测结果表明,大部分吊杆存在锚头密封不严、锚杯积水及PE护套破损开裂等现象,吊杆外观情况较差,短吊杆钢丝锈蚀状况为标度4,处于较差的状态.吊杆疲劳寿命根据桥梁实际车流量和疲劳应力幅值进行预测,计算得出吊杆在无腐蚀状态下的寿命约为44年,且在吊杆发生腐蚀后,其服役年限也不到无腐蚀吊杆的1/5,即吊杆出现腐蚀后服役年限不足10年.确认吊杆存在较大的安全隐患,建议对大桥的吊杆进行更换.