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Ultimate bearing capacity analysis of jacket platforms based on vibration response |
L Tao, XU Changhang, CHEN Guoming, ZHAO Kang, LIU Hongbing
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(Centre for Offshore Engineering and Safety Technology, China University of Petroleum, Qingdao 266580, China)
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Abstract: |
In order to assess the safety of the jacket platform which has served for many years, ultimate bearing capacity analysis method based on vibration monitoring was proposed. Vibration monitoring was carried out at CEP jacket platform of a gas field in the East China Sea, and the acceleration responses of top side module were collected under different sea conditions. The characteristic function of platform vibration response was extracted using random decrement technique. Furthermore, time series analysis and complex exponential method were used to identify the dynamic parameters for the characteristic function. The frequency databases of different damage modes were established by finite element analysis of the platform under various damaged conditions. Health conditions of platform structure were recognized by comparing identification results of modal parameter with frequency database. Nonlinear dynamics analysis was conducted by time domain analysis method, and dynamic ultimate bearing capacity analysis method was established. Field application results show that the updating model based on vibration monitoring can reflect real health status of platform structure, and the structural resistance can be assessed accurately by conducting the ultimate bearing capacity analysis of model updating method, which leads to time-varying structural resistance of platform. |
Key words: vibration monitoring jacket platform dynamic parameters identification time domain analysis nonlinear dynamics ultimate bearing capacity |
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