In this paper, the full-life cycle optimization model of offshore jacket platform is proposed based on the work environment and structural property. The initial investment, maintenance cost and failure loss cost are unified into the model. In the full-life cycle model, the total cost of the jacket platform structure system in its full service period is taken as the objective function and the initial reliability vector of the layer elements partitioned in advance is taken as the design variables. Different full-life cycle optimization models can be obtained with respect to considering the system reliability constraint or not.
By now in the world, steel jacket platform is the main type platform constructed in ocean, which is made up of the rigid deck, subjacent jacket and the steel piles penetrating the jacket legs. For the optimization design of the jacket platform in the past, people usually pay more attention to the economical efficiency and reliability of the initial design and overemphasized the initial engineering investment, even sometimes only considered the initial cost (Lessen, 1993; Feng, 2000). But sometines, the maintenance cost of a structure is far greater than the initial investment (Wang, 2000). Because the work environment of offshore platform is extraordinarily complex, structural failure will bring about large loss of human and capital (Baker, 1999). In addition, the bearing capacity of jacket platform will decay gradually for the quality defects and some man-induced factors. In order to fulfill the safety and normal operating requirements, it is needed to perform periodic maintenance to extend the service life and to keep its function. The full-life cycle optimization design considering the deterioration of bearing capacity during service life has attracted the attention of many researchers (Hitoshi, et, al., 1996; Frangopol, et, al., 1997).
