Research Of Structure Optimum Design For Jacket Offshore Platforms

Based on the theory of structural optimum design, aseismic design for engineering structures, engineering fuzzy set, combining the offshore platform code, construction structure aseismic code, and the platform structure optimization features had been taken into consideration , some problems of platform structure were studied. The major contents are summarized as follows:1. Jacket platform was assumed as steel frame structure and optimum design method was performed. Total weight of the structure was selected to be optimal objectives. Average diameter and wall thickness of the structural element were taken as design variables. Constraint conditions such as strength, stiffness, stability were taken into account. As an example, the deposited oil Offshore Platform BZ28-1 of Bohai Oil Field in China was numerated. The results show that the proposed method is significative in the design of the platforms.2. The model of structural fuzzy optimum design of earthquake-resistant for offshore jacket platforms was established. Design variables, object function and constrained conditions in the fuzzy optimum mode were considered with fuzzy method. The tolerance coefficient of the constrained condition boundary was determined with fuzzy optimization method. The fuzzy optimum solutions of fuzzy optimization problem of earthquake-resistant were obtained with bound search method. Structure fuzzy optimum design of earthquake-resistant was performed for Platform BZ28-1 of Bohai Oil Field in China. The results show that the optimum design for jacket platforms considering fuzzy factors is more scientific and feasible.3. Jacket platform was assumed as steel frame structure and multi-objective design method was performed. Total weight and stability of the structure and were selected to be optimal objectives. Average diameter and wall thickness of the structural element were taken as design variables. Constraint conditions such as strength, stiffness, stability were taken into account. As an example, the Chengbei Offshore Platform 11# of Shengli Oil Field in China was numerated with genetic algorithms. The results show that the proposed method is significative in the design of the platforms.4. Total weight and seismic strain energy of the structure and were selected to be optimal objectives. Average diameter and wall thickness of the structural element were taken as design variables. Constraint conditions such as strength, stiffness, stability were taken into account. As an example, the deposited oil Offshore Platform BZ28-1 of BohaiOil Field in China was numerated with genetic algorithms. The results show that the proposed method is significative in the design of the platforms.5. Theory and method of optimum design of earthquake-resistant structures based on optimal fortification intensity were introduced. Optimum design was performed for Platform BZ28-1 of Bohai Oil Field in China according to principle of three-level fortification and aseismic design method of two-stage of code for aseismic design of buildings. In its objective function, cost and loss expectation were both taken into consideration. The optimum design project of considering cost and loss expectation was obtained.6. Jacket platform was assumed as steel frame structure and the pile-soil-structure interaction was considered. Optimum method was applied to aseismic design of structure. Total weight of the structure was selected to be optimal objectives. Average diameter and wall thickness of the structural element were taken as design variables. Constraint conditions such as strength, stiffness, stability were taken into account. As an example, the deposited oil Offshore Platform BZ28-1 of Bohai Oil Field in China was numerated. The results show that the proposed method is significative in the design of the platforms.7. For the shallow oil field, cost and benefit were both taken into consideration, single-leg jacket platform was designed. The static analysis for it was performed, under combination of load cases of...