ON RELIABILITY AND ACTIVE CONTROL OF TENSION LEG PLATFORMS

This dissertation is concerned with safety and structural integrity of offshore Tension Leg Platforms (TLP) subject to extreme environmental loadings. A reliability model is presented and the technique of active control is considered as one of the possible means for ensuring structural safety during severe loading episodes.; The proposed reliability model is used to assess the probability of progressive failure of the legs at each corner of a TLP and the reliability of the mooring system during its service life as a function of various design parameters.; The control method proposed is designed to ensure that maximum tension in the mooring legs is limited to its safety values at all times. It consists of generating control forces in a feedback fashion using pulse generators located at the corners of the platform. An open-loop adaptive control algorithm is developed and its feasibility is discussed.