STRESS ANALYSIS IN BOX BOTTOM OF IRAN AMIRKABIR SEMI-SUBMERSIBLE PLATFORM DUE TO HOOK LOAD CONDITION UNDER ENVIRONMENT LOADS

Semi-submersible rigs are floating multi-hull structures that include a deck, four or more columns, and two submerged pontoons. Columns can also be connected withhorizontal bracings. The deck usually consists of three or more levels of upper deck, tween deck, lower deck and box bottom. Regarding the harsh marine environmentsurrounding these structures, numerous factors can damage them. Therefore, there are always concerns about their integrity and stability as they cannot undergo routine and continuous inspection. On the other hand, inspections of offshore platforms require squad-diving and expensive marine equipment. Development of advanced damage detection methods allows for examination of the structure as a whole before detailed inspections to be investigated at the damaged area, if such damage is detected.