Optimal Design, Based On The Reliability Of Offshore Platform Structure

Offshore jacket platform is the foundational facility for offshore oil exploiting, and the base for marine producing and living. At present some achievements have been made on the -study of offshore jacket platform structure system. But the most of them are the static dynamical analysis, safety assessed and deterministic optimum design. In this paper, the uncertainty of the loads, geometry and materials of the structure are considered, and a model of reliability-based structural optimum design is established. A method no need of manual intervention for reliability optimization of complex structure is found by applying APDL language interface provided by ANSYS that is a large-scale software for finite element analysis. ANSYS and DOT (Design Optimization Tools) are jointed in this method. And it is showed reasonable, effective and economical via the numerical value and analysis of the optimization result of Shengli CB11F offshore platform. A new idea and method for the large reliability-based complicated structure optimum design is provided. As follows:In chapter 1, the engineering background and the meaning of optimization of offshore platform are presented. Sum up the research developments in domestic and abroad. In the last section, the brief description of the research in this dissertation is presented.In chapter 2, the basic theory and common computation method of structural reliability is given, and the improvement on original method in application.In chapters, reliability-based structure optimization design is investigated, including reliability-based truss structural topology optimization and two reliability optimization methods based on second development of ANSYS software. Numerical examples are given and the results indicate the validity and some shortages of these methods. Some reformative methods are raised.In chapter 4, a model with random parameter of reliability-based offshore platform structure optimization design method is established. The result of the reliability-based optimization of CB11F offshore platform in Shengli oil fields shows that the method is reasonable and economical.In chapter 5, the main contributions of the thesis is summarized and the further work is suggested.National Nature Science Foundation of China (No. 59895410) supports this thesis.