Modal parameters identification and safety assessment of a typical long-span steel trestle under extended service in sea port
LIU Hongbiao1, 2, LI Hongnan1
1. Faculty of Infrastructure Engineering，Dalian University of Technology，Dalian 116024，China;
2. National Engineering Laboratory for Port Hydraulic Construction Technology, Tianjin Research Institute for Water Transport Engineering, M.O.T, Tianjin 300456, China
Abstract：There is little study on the dynamic properties of long-span steel trestle under extended service in sea port. According to the field modal testing and the calculation analysis of finite element numerical simulation, the dynamic properties of long-span steel trestle with a span of 106m under extended service in sea port are studied, and the influence of different exciting ways to the results of modal parameters identification is cleared. Then the modal parameters of steel trestle with a span of 106m under extended service were obtained, which is typical simply-supported through-type parabolic vierendeel truss structure. Based on the natural frequencies of steel trestle obtained in three years, the safety state of the trestle is assessed with the variety of natural frequencies of the trestle. The filed test results and their analysis show that the results of trestle natural frequencies obtained by the ambient measurement are same as that obtained by the initial velocity exciting method and the initial displacement exciting method. So the three test methods can be selected freely based on the field conditions when carrying out the structural modal test, because the results obtained by the three methods are same. Based on the modal parameters of trestle obtained by the field test, it is clear that the damp ratio of trestle is not more than 0.03, the first mode natural frequency in vertical is about 1.70Hz, and its first mode vibration shape has a node of vibration mode. All the above are the big pictures of the simply-supported through-type parabolic vierendeel steel truss structure. The safety state of trestle is thought good based on the safety assessment with the natural frequencies of trestle obtained in three years, and the conclusion is same as the visual inspection result of trestle. The work and conclusions above can provide experience reference for engineer to carry out modal test and safety inspection assessment of simply-supported through-type parabolic vierendeel steel truss trestle of oil wharf.
刘红彪1,2，李宏男1. 超期服役大跨海港钢栈桥结构动力特性测试分析与安全评估[J]. 振动与冲击, 2016, 35(7): 62-68.
LIU Hongbiao1, 2, LI Hongnan1. Modal parameters identification and safety assessment of a typical long-span steel trestle under extended service in sea port. JOURNAL OF VIBRATION AND SHOCK, 2016, 35(7): 62-68.
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