Long-term response of tension leg platforms
Conference Paper
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abstract
The current state-of-the-practice in the global performance design verification of tension leg platforms (TLP) relies on conventional short-term response analysis techniques to estimate the extreme platform responses during a prescribed design storm environment (e.g. a 100 year hurricane) with collinear wind, waves and current conditions. However, the TLP responses are sensitive to non-aligned wind, wave and current, which may result in significant variations in extent airgap (minimum under deck wave clearance) and extreme tendon tensions. In the Gulf of Mexico such conditions can occur during the passage of the eye of a hurricane. Their effect on the global performance of TLP's can be evaluated by investigating the long-term response characteristics. The paper discusses a simple and efficient long-term response analysis method, which can be used to derive consistent design criteria and can be readily incorporated in the design process. The method is applied to TLP in deep water. The 100 year long-term extreme responses are compared with the short-term 100 year hurricane design estimates. Moreover, for a given storm at a particular site, the temporal variations of extreme airgap and tendon tension are explored to provide enhanced insight into the sensitivity of TLP responses to varying wind, waves and current.
