Reliability Assessment of Frame Structures Based on Ultimate Strength Analysis

1. 提出了一种基于极限强度分析的空间框架结构可靠性评估体系。(1)采用轴力、剪力、双轴弯矩和扭矩共同作用下的截面线性化破坏条件，对其极限破坏进行评估。(2)采用塑性节点法和有限元法相结合的方法计算了极限破坏模式的安全裕度。(3)采用分支定界法结合启发式运算选择随机优势崩溃模式。该系统已成功地应用于船舶主体结构，并将其建模为空间框架结构，承受各种概念荷载条件。通过某大型油轮（240，OOODWT）的数值算例，并与以往平面框架模型的结果进行比较，研究了船舶主体结构极限强度的概率特性。（见参考资料1）并将该系统应用于典型的正交加劲板结构，作为船体底板极限强度分析的基础研究，将其建模为平面框架，承受面内压缩和侧向压力的联合作用。通过数值算例和与前人研究的比较，验证了所提方法的适用性。（参见参考文献2和3。）

1. A system is developed for reliability assessment of spatial frame structures based on ultimate strength analysis. (1) Ultimate collapse is evaluated by using a linearized failure condition of the section under the combined effect of axial force, shearing forces, biaxial bending moment and torsional moment. (2) A plastic node method combined with a finite element method is used to generate the safety margins of ultimate collapse modes. (3) Stochastically dominant collapse modes are selected by applying the so-called branch-and-bound methods combined with heuristic operations.2. The system is successfully applied to ship main structures, which are modelled as spatial frame structures and subjected to various notional loading conditions. Probabilistic properties of ultimate strength of ship main structures are investigated through the numerical examples for a large tanker (240,OOODWT) and comparison with previous results for plane frame models. (See reference 1.)3. The system is also applied to typical plate structures having orthogonal stiffeners as a basic study on ultimate strength analysis of ship bottom platings, which are modelled as plane frames and subjected to combined in-plane compression and lateral pressure. Through numerical examples and comparison with previous researches, the applicability of the proposed methods is demonstrated. (See references 2 and 3.)