Research Initiation: Sensitivity Analysis and Failure Cost Design of Random Structural Systems in Load Space

结构可靠度评估方法已从构件分析发展到系统分析。利用非线性结构分析程序推导出荷载空间的极限状态和使用极限状态。在三维荷载空间中，通过对破坏区域内外加荷载的联合密度函数积分计算系统的破坏概率。通过假设某些楼层荷载之间的正完全相关，可以将荷载空间尺寸减小到3个。结构变异性是通过荷载空间中极限状态函数的随机化来建模的，而不需要任何额外的结构分析。研究了失效概率对载荷和阻力变量的敏感性，并指出了有重要贡献的因素。提出了一种系统的载荷空间设计方法，该方法采用单目标和多目标线性规划的方法，对失效模式和总预期成本的最小化施加权重。结果是几个实际结构的未来（或失效）成本与初始成本之间的权衡曲线。

Methods of evaluating structural reliability have advanced from member to system analysis. A nonlinear structural analysis program is utilized to derive ultimate and serviceability limit states in load space. System probability of failure is computed by integration of the joint density function of applied loads in the failure region in a three-dimensional load space. The reduction of load space dimensions to three is possible by assumption of positive perfect correlation amongst certain floor loads. Structural variability is modeled by randomization of the limit state function in load space without requiring any additional structural analysis. Sensitivity of failure probability to load and resistance variables are studied and factors with significant contributions are noted. A systematic load space approach to design, based on applying weights to modes of failure and minimization of the total expected cost using single and multiobjective linear programming, is developed. Results are trade-off curves between future (or failure) cost and initial cost for several realistic structures.