| Damage Localization of Offshore Platforms Under Ambient Excitation |
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| 引用本文： | YANG,He-zhen(杨和振),LI,Hua-jun(李华军),WANG,Shu-qing(王树青). Damage Localization of Offshore Platforms Under Ambient Excitation[J]. 中国海洋工程, 2003, 17(4): 495-504 |
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| 作者姓名： | YANG He-zhen(杨和振) LI Hua-jun(李华军) WANG Shu-qing(王树青) |
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| 作者单位： | College of Engineering，Ocean University of China，Qingdao 266071，China，College of Engineering，Ocean University of China，Qingdao 266071，China，College of Engineering，Ocean University of China，Qingdao 266071，China |
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| 基金项目： | This work was financially supported by 863 Project of China(Program No.2001aa602023-1),and by the Teaching and Research Award Program for Outstanding Young Teachers in Higher Education Institutions of Ministry of Educa-tion of China. |
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| 摘 要： | In this paper Nondestructive Damage Detection (NDD) for offshore platforms is investigated under operational conditions. As is known, there is no easy way to measure ambient excitation, so damage detection methods based on ambient excitation have become very vital for the Structural Health Monitoring (SHM) of offshore platforms. The modal parameters (natural frequencies, damping ratios and mode shapes) are identified from structural response data with the Natural Excitation Technique (NExT) in conjunction with the Eigensystem Realization Algorithm (ERA) . A new method of damage detection is presented, which utilizes the invariance property of element modal strain energy. This method is to assign element modal strain energy to two parts, and defines two damage detection indicators. One is compression modal strain energy change ratio (CMSECR); the other is flexural modal strain energy change ratio (FMSECR). The present modal strain energy is obtained by incomplete modal shape and structural stiffness matr
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Damage Localization of Offshore Platforms Under Ambient Excitation |
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| YANG He-zhen LI Hua-jun and WANG Shu-qingCollege of Engineering,Ocean University of China,Qingdao ,China. Damage Localization of Offshore Platforms Under Ambient Excitation[J]. China Ocean Engineering, 2003, 17(4): 495-504 |
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| Authors: | YANG He-zhen LI Hua-jun WANG Shu-qingCollege of Engineering Ocean University of China Qingdao China |
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| Affiliation: | College of Engineering, Ocean University of China, Qingdao,266071, China College of Engineering, Ocean University of China, Qingdao,266071, China College of Engineering, Ocean University of China, Qingdao,266071, China |
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| Abstract: | In this paper Nondestructive Damage Detection (NDD) for offshore platforms is investigated under operational conditions. As is known, there is no easy way to measure ambient excitation, so damage detection methods based on ambient excitation have become very vital for the Structural Health Monitoring (SHM) of offshore platforms. The modal parameters (natural frequencies, damping ratios and mode shapes) are identified from structural response data with the Natural Excitation Technique (NExT) in conjunction with the Eigensystem Realization Algorithm (ERA) . A new method of damage detection is presented, which utilizes the invariance property of element modal strain energy. This method is to assign element modal strain energy to two parts, and defines two damage detection indicators. One is compression modal strain energy change ratio (CMSECR); the other is flexural modal strain energy change ratio (FMSECR). The present modal strain energy is obtained by incomplete modal shape and structural stiffness matrix. Structural health monitoring is thus accomplished via monitoring the elemental CMSECR and FMSECR. Several damage cases are simulated by an offshore platform numerical model, and presented to illustrate the utility of the proposed method. According to the damage localization results, the proposed method is shown to be effective and precise for complex structural damage detection. |
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| Keywords: | offshore platform modal parameter identification damage detection modal strain energy |
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