Title

Structural modification by reassigning natural frequencies of offshore jacket platforms

Document Type

Conference Proceeding

Date of Original Version

9-19-2011

Abstract

Offshore jacket platforms have been widely used in offshore oil and gas exploitation under hostile ocean environments. Structure damages, which may cause the change of natural frequencies, are unavoidable due to the severe environmental loads. If the natural frequencies of a damaged structure become close to the ambient vibration frequencies, excessive vibration of the platform would occur. In order to reduce the vibration level, a structural modification procedure of reassigning the natural frequencies of the platform is desired. In this paper, a structural modification algorithm aiming at reassigning natural frequencies of an offshore jacket platform is newly developed. The modifications are demonstrated either by installing a tuned mass damper at the deck, or by modifying the stiffness of floor members, of the platform. For verifying the developed algorithm, numerical studies based on finite element models are conducted for a simplified jacket platform. Numerical results indicate that the developed algorithm can properly assign the natural frequencies of the modified platform based on the preset frequencies. Copyright © 2011 by the International Society of Offshore and Polar Engineers (ISOPE).

Publication Title

Proceedings of the International Offshore and Polar Engineering Conference

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