Structural damage detection of offshore platforms considering environmental variations
WU Wenkai1, XU Mingqiang1, WANG Shuqing1, JIANG Yufeng1, WANG Guoxing2
1.College of Engineering, Ocean University of China, Qingdao 266100, China;
2.Naval Architecture and Port Engineering College, Shandong Jiaotong University, Weihai 264200, China
Abstract:Offshore platforms continually serve in atrocious ocean environment, imposing the occurrence and growth of structural damage.Environmental variations, such as temperature, marine growth, foundation scour, and etc., tend to mask the changes of structural dynamic features caused by damage.To this end, the vibration-based methods cannot be used to identify the existence of the damage.In this paper, a cointegration analysis-based method was proposed for damage detection of offshore platforms and the cointegration residuals of natural frequencies extracted by the cointegration analysis were used to remove the environmental variations.Further, the X-bar chart was used to determine the occurrence of damage.The influence of temperature, including air temperature, water temperature and seabed mud temperature was simultaneously considered because temperature is the most common condition that changes the dynamic features of structures.The performance of cointegration method was explored and compared with the principle component analysis, which has been constantly used for damage detection under environmental variations.Results show that both methods can successfully remove the temperature influence and accurately identify the damage.The cointegration performs more robust with a low noise level while the principle analysis behaves well with a high noise level.Besides, cointegration has a lower misjudgment rate in the case of small baseline sample.
[1]李华军,刘福顺,王树青.海洋平台结构模态分析与损伤检测[M].北京:科学出版社,2017.
[2]ZHANG C, CHENG L, QIU J H, et al.Structural damage detections based on a general vibration model identification approach[J].Mechanical Systems & Signal Processing, 2019, 123:316-332.
[3]FARRAR C R, DOEBLING S W, NIX D A.Vibration-based structural damage identification[J].Philosophical Transactions of the Royal Society A: Mathematical,Physical & Engineering Sciences, 2001, 359:131-149.
[4]WORDEN K, FARRAR C R, MANSON G, et al.The fundamental axioms of structural health monitoring[J].Proceedings of the Royal Society A: Mathematical Physical & Engineering Sciences, 2007, 463(2082):1639-1664.
[5]WOOD M G.Damage analysis of bridge structures using vibrational techniques[D].Birmingham: University of Aston,1992.
[6]ASKEGAARD V, MOSSING P.Long term observation of RC-bridge using changes in natural frequencies[J].Nordic Concrete Research, 1998, 7:20-27.
[7]DOEBLING S W, FARRAR C R.Using statistical analysis to enhance modal-based damage identification[C]∥2nd International Conference on Damage Assessment of Structures.Sheffield:University of Sheffield, 1997.
[8]FARRAR C R, BAKER W E, BELL T M, et al.Dynamic characterization and damage detection in the I-40 bridge over the Rio Grande[R].Los Alamos: Los Alamos National Laboratory, 1994.
[9]PEETERS B, MAECK J, ROECK G D.Vibration-based damage detection in civil engineering: excitation sources and temperature effects[J].Smart Materials & Structures, 2001, 10(3):518-527.
[10]YAN A M, KERSCHEN G, BOE P D, et al.Structural damage diagnosis under varying environmental conditions:part I: a linear analysis[J].Mechanical Systems & Signal Processing, 2005,19(4): 847-864.
[11]YAN A M, KERSCHEN G, BOE P D, et al.Structural damage diagnosis under varying environmental conditions:part II: local PCA for non-linear cases[J].Mechanical Systems & Signal Processing, 2005, 19(4):865-880.
[12]吴森,韦灼彬.基于主成分残差的结构损伤识别方法[J].公路交通科技,2011,28(7):113-117.
WU Sen, WEI Zhuobin.Structure damage identification based on residual error of principal component[J].Journal of Highway and Transportation Research and Development,2011,28(7):113-117.
[13]常鹏,王英剑,吴云峰,等.基于主成分分析的温度敏感性结构损伤识别[J].振动工程学报,2019,32(2):234-240.
CHANG Peng, WANG Yingjian, WU Yunfeng, et al.Damage detection of temperature-sensitivitive structures based on principal component analysis[J].Journal of Vibration Engineering,2019,32(2):234-240.
[14]WANG S Q, WANG H Y, XU M Q, et al.Identifying the presence of structural damage: a statistical hypothesis testing approach combined with residual strain energy [J].Mechanical Systems & Signal Processing,2020,140:106655.
[15]CROSS E J, WORDEN K, CHEN Q.Cointegration: a novel approach for the removal of environmental trends in structural health monitoring data[J].Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 2011, 467(2133):2712-2732.
[16]WORDEN K, CROSS E J, KYPRIANOU A.Cointegration and nonstationarity in the context of multiresolution analysis[J].Journal of Physics: Conference Series, 2011,305:012004.
[17]梁亚斌,李东升,李宏男.环境温度影响下基于频率协整的在线损伤识别[J].大连理工大学学报,2014,54(3):307-314.
LIANG Yabin, LI Dongsheng, LI Hongnan.Online damage detection based on frequencies cointegration considering environmental variations[J].Journal of Dalian University of Technology, 2014, 54(3): 307-314.
[18]刁延松,曹亚东,孙玉婷.环境变化下基于AR模型系数和协整的海洋平台结构损伤识别[J].工程力学,2017,34(2):179-188.
DIAO Yansong, CAO Yadong, SUN Yuting.Structural damage identification based on AR model coefficients and cointegration for offshore platform under environmental variations[J].Engineering Mechanics,2017,34(2):179-188.
[19]HUANG J Z, LI D S, LI H N, et al.Damage identification of a large cable-stayed bridge with novel cointegrated Kalman filter method under changing environments[J].Structural Control and Health Monitoring,2018,25(4):e2152.
[20]DICKEY D A, FULLER W A.Likelihood ratio statistics for autoregressive time series with a unit root[J].Econometrica, 1981,49:1057-1072.
[21]JOHANSEN S.Likelihood-based inference in cointegrated vector autoregressive models[M].Oxford: Oxford University Press, 1995.
[22]BANERJEE A, DOLADO J J, GALBRAITH J W,et al.Co-integration, error correction, and the econometric analysis of non-stationary data[M].Oxford: Oxford University Press,1993.
[23]FAWCETT T.An introduction to ROC analysis[J].Pattern Recognition Letters, 2005, 27(8):861-874.
[24]WOON C E, MITCHELL L D.Variations in structural dynamic characteristics caused by changes in ambient temperature: I.experimental[J].14th International Modal Analysis Conference.Dearborn:IMAC, 1996.