Document Type : Original Manuscript
Authors
1 Department of Marine Industries, Faculty of Engineering, Science and Research Branch, Islamic Azad university, Tehran, Iran.
2 Department of Maritime Engineering, Amir Kabir University of Technology, Tehran, Iran.
3 Department of Civil Engineering, Faculty of Engineering, Science and Research Branch, Islamic Azad university, Tehran, Iran.
Abstract
The passage of personnel and the placement of facilities on the access stairs of offshore complexes have made it very important to identify damage to these components. Modal strain energy method is one of the non-destructive and practical methods in which using changes in the dynamic properties of the structure to identify the location and determine the severity of damage in the structure. In recent years, modifications have been made to the initial version of this method, one of which is to take into account the natural frequencies in locating the damage. In this paper, using the improved modal strain energy method and considering natural frequencies, a new relationship is presented to more accurately identify the location of damage in the structure and three different damage indices in the offshore platform access bridge structure are studied and compared. The results show that the average error to accurately identify the location of damage in the average Stubbs index, the improved method and the novel method are 3.55, 2.82 and 2.21 percent, respectively, so the novel method is able to more accurately identify the location of damage in the structure. Also, comparing the results of different cases shows that the average damage location error decreases with increasing damage severity. The accuracy of identifying the location of the damage also increases when move away from the supports.
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