Practical Method of Reliability-based Assessment and Lifecycle Management of Deteriorating Existing Structures

继续利用现有结构是实现可持续社会的最重要因素之一。为了评估这种结构的持续未来的服务，简单和实用的工具需要开发用于评估的时间依赖的可靠性和性能的structurs.The调查员已经引入了一个阻力折减系数的概念，以考虑到其性能水平的退化的结构组件的影响，在标量值。有了这个因子，时间相关的可靠性问题可以近似为一个时间无关的，现有的简单方法，如AFOSM可以用于可靠性评估。在这项研究中，提出了一个实用的公式阻力减少因子的分类的累积分布函数根据父分布的极值分布。数值算例表明，该方法给出的估计误差较大 ...更多信息 当主负载的变化性小和/或电阻的变化性大时。然而，误差水平与AFOSM引起的误差相当，并且在实践中不会引起问题。定期的在役检查和适当的维护可以使退化的结构部件恢复到接近原始状态。由于检查和维护成本高昂，因此需要在检查的范围和准确性、所需的可靠性水平和成本之间进行权衡。为了设计一个最优的检测/维护策略，使期望的全寿命周期总费用最小，通常必须解决非线性优化问题。该实用方法可应用于估算阻力折减系数，包括当构件的强度由于诸如恢复而随时间不连续地变化时的情况。该方法避免了结构的时变可靠性分析，计算时间可减少约五十分之一。少

The continued use of existing structures is one of the most important factors for achieving sustainable society. In order to assess such structures for continued future service, simple and practical tools need to be developed for evaluating the time-dependent reliability and performance of the structures.The investigator has introduced the concept of a resistance reduction factor in order to take the impact of degradation of a structural component on its performance level into account in a scalar value. With the factor a time-dependent reliability problem can be approximated as a time-independent one and existing simple methods such as AFOSM can be used for reliability assessment. In this research, a practical formula for a resistance reduction factor is proposed classifying the cumulative distribution functions according to the classification of parent distributions of extreme value distributions. Numerical examples show that the method provides an estimate with relatively large error … More when the variability in the principal load is small and/or the variability in the resistance is large. Yet the error level is comparable with the error due to AFOSM and would not cause a problem in practice.Periodic in-service inspection followed by suitable maintenance may restore a degraded structural component to near-original condition. Since inspection and maintenance are costly, there are tradeoffs between the extent and accuracy of inspection, required level of reliability, and cost. To design an optimum inspection/maintenance strategy with minimum expected total lifecycle cost, generally non-linear optimization problem must be solved. The practical method can be applied to estimate a resistance reduction factor including the cases when the strength of a component changes discontinuously in time due to, such as, restoration. Using the proposed method, the time-dependent reliability analysis can be avoided in the optimization and the computational time can be reduced about a fiftieth. Less