Reliability Assessment of Frame Structures Based on Ultimate Strength Analysis

1.建立了基于极限强度分析的空间框架结构可靠性评估系统。(1)采用轴力、剪力、双向弯矩和扭矩共同作用下截面的线性化破坏条件来评估极限倒塌。(2)采用塑性节点法和有限元相结合的方法计算极限倒塌模式的安全裕度。(3)采用分枝定界法和启发式运算相结合的方法选择随机占优的倒塌模式。该系统已成功地应用于船舶主结构，将其建模为空间刚架结构，并受各种名义载荷条件的影响。通过对一艘大型油轮(240，OOODWT)的数值算例，并与已有的平面框架模型结果进行比较，研究了船舶主结构极限强度的概率特性。(见参考文献1.)3.该系统也适用于具有正交加强板的典型板结构，作为船底钢板极限强度分析的基本研究，该钢板被建模为平面刚架，并受到面内压缩和侧压力的联合作用。通过数值算例和与前人研究结果的比较，验证了所提方法的适用性。(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.)