海洋平台结构系统可靠性分析及其构件安全等级评判

海洋平台在服役期间将遭遇恶劣的环境载荷，研究其系统可靠性并评价其构件安全等级有着重大意义。本文采用分技界限法寻找结构的主要失效路径，以Ditlevsen界限法求取结构的系统失效概率，最后引进模糊综合评判方法对结构作综合评判．由此得到结构构件的安全等级。文中还具体分析了圆管截面极限方程的建立，讨论了影响系数对系统可靠性计算的影响，得到影响系数与系统失效概率的定性关系。按以上思路编制了空间刚架的通用可靠性分析程序，算例表明程序是合理有效的。

SYSTEM RELIABILITY ANALYSIS OF OFFSHORE STRUCTURES AND COMPONENT SAFETY RANKASSESSMENT

In this paper, the branch-and-bound method is adopted to search the main failure pathand Ditievsen bound method is used to calculate system failure probability. The structureis then assessed by fuzzy comprehensive assessment method, which gives the structuralcomponent safety rank- The ultimate equation of the tubular cross-section is analyzedbased on ultimate strength analysis. Influence of effect coefficients on structure systemfailure probability is investigated, and the basic results are obtained. General program forspatial frame structures using above method is developed, which is verified by numericalexamples.