ABSTRACT

Semi-submersible off-shore rigs are widely operated in offshore oil and gas industry, especially it serves the purpose of drilling, exploration, installation and accommodation purposes. It is designed for operating in deep waters and harsh environments. Fatigue damage is known as one of the unavoidable problems for offshore steel structures. Depending on the design type; a semi-submersible hull structure consists of connections that are prone to fatigue damage. Fatigue analyses should be carried out during the design stage so that the hull structure can have an adequate fatigue life. The main objective of this study is to calculate global fatigue damage and confirm the adequacy of the deepwater semi-submersible rig for 40 ~ 400 years life, where the structural components with respective design fatigue factors are accounted for. The results and insights derived from the present study are summarized and discussed.