斜拉索模态试验参数研究
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摘要
试验模态分析是斜拉桥索力测试中广泛应用的方法。该方法的关键之一是采取合理的试验方案获取可靠的响应信号以识别出正确的索振动频率。本文通过试验,详细讨论了斜拉索模态测试中若干试验参数,如激振类型、激振位置、传感器位置以及频率分辨率对试验结果的影响;比较环境激励与锤击激励的效果,验证了环境激励的方法也可以准确识别索的频率;最后给出了较为合理的斜拉索模态试验方案,用该方案确定的索力与理论计算结果相差不超过 1. 5%。
Experimental modal analysis and testing is one of the most widely used techniques for the measurement of tension forces in stay cables. For the modal testing of stay cables, adoption of proper experimental methodology for acquiring the reliable signals plays a key role for accurate identification of the cable frequencies. In this paper, a stay cable model experiment was conducted in laboratory to determine the effects of the variables such as type and placement of excitations, arrangement of accelerometers, sampling frequency and frequency resolution etc. Comparing the frequencies identified by the ambient excitation with those by the hammer excitation, it is demonstrated that the ambient excitation is good enough to identify the frequencies of stay cables interested. A feasible experimental procedure was presented for accurate determination of the stay cables frequencies. The results show that the tensions of the stay cable experimentally determined achieve an error of less than 1.5% by comparing those with the theoretical prediction.
Experimental modal analysis and testing is one of the most widely used techniques for the measurement of tension forces in stay cables. For the modal testing of stay cables, adoption of proper experimental methodology for acquiring the reliable signals plays a key role for accurate identification of the cable frequencies. In this paper, a stay cable model experiment was conducted in laboratory to determine the effects of the variables such as type and placement of excitations, arrangement of accelerometers, sampling frequency and frequency resolution etc. Comparing the frequencies identified by the ambient excitation with those by the hammer excitation, it is demonstrated that the ambient excitation is good enough to identify the frequencies of stay cables interested. A feasible experimental procedure was presented for accurate determination of the stay cables frequencies. The results show that the tensions of the stay cable experimentally determined achieve an error of less than 1.5% by comparing those with the theoretical prediction.
引文
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[6] 刘志军,党志杰,罗元文等.振动法测定缆索张力的研究[J].桥梁建设,2002年第2期(LIUZhi-jun,DANGZhi-jie,LUOYuan-wen,etal.StudyontheDeterminationofCableTensionbyVibrationMethod.BridgeConstruction,2002,(2)(inChinese))
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[2] 陈刚,任伟新.基于环境振动的斜拉桥拉索基频识别[J].地震工程与工程振动,2003,23(3):100~106(CHENGang,RENWei-xin.Ambientvibrationbasedidentificationoffundamentalfrequenciesofstaycables.EarthquakeEngi neeringAndEngineeringVibration,2003,23(3):100~106(inChinese))
[3] 张令弥.振动测试与动态分析[M].北京:航空工业出版社,1992(ZHANGLing-ni.VibrationMeasurementsAndDy namicAnalysis.Beijing:PublishingHouseofAircraftIndustry,1992(inChinese))
[4] 傅志方,华宏星.模态分析理论与应用[M].上海:上海交通大学出版社,2000(FUZhi-fang,HUAHong-xing.Mo dalAnalysisTheoryAndApplication.Shanghai:ShanghaiJiaotongUniversityPress,2000(inChinese))
[5] HeylenW,LammensS,SasP.ModalAnalysis-TheoryandTesting[M].KatholiekeUniversiteitLeuven,1997
[6] 刘志军,党志杰,罗元文等.振动法测定缆索张力的研究[J].桥梁建设,2002年第2期(LIUZhi-jun,DANGZhi-jie,LUOYuan-wen,etal.StudyontheDeterminationofCableTensionbyVibrationMethod.BridgeConstruction,2002,(2)(inChinese))
[7] 陈刚.振动法测索力与实用公式[D].福州大学硕士学位论文,2004.1, http://bridge.fzu.edu.cn(CHENGang,PracticalFormulasforEstimationofCableTensionbyVibrationMethod,M.ScThesis,FuzhouUniversity,2004.1, http://bridge.fzu.edu.cn(inChinese))
[8] MehrabiAB,TabatabaiHA.UnifiedFiniteDifferenceFormulationforFreeVibrationofCables[J].JournalofStructuralengineering,ASCE,1998,124(11):1313~1322
[9] ZuiH,ShinkeT,NamitaY.PracticalFormulasforEstimationofCableTensionbyVibrationMethod[J].JournalofStruc turalEngineering,ASCE,1996,122(6):651~656
[10] IrvineHM.CableStructures[M].Cambridge:TheMITPress,1981
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