Reliability Analysis Method for Degrading Structures Taking Combination of Load Processes into Account

考虑荷载过程组合的退化结构可靠性分析方法

• 批准号: 11650582
• 负责人: MORI Yasuhiro
• 金额: $ 2.24万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11650582/
• 关键词: Structural Reliability; Limit State Design; Structural Degradation; Load and Resistance Factors; Load Combination; Stochastic Process; Inspection and Maintenance

The deterioration of infrastructures is a widespread problem in many countries. 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.When more than one time-varying load act on a structure, the maximum intensity of the combination during the reference period needs to be considered. This project first developed the theoretical expressions of the cumulative distribution function (cdf) of the maximum intensity of the combination. Numerical examples show that the theoretical expression of the cdf provides fairly good estimate regardless of the statistical characteristics of the load intensity and stochastic processes.Then the concept of a resistance reduction factor due to degradation of a component is introduced to approximate a time-dependent reliability problem as a time-independent one. With the factor the time-varying resistance can be equivalentl … More y replaced with a time-invariant resistance, and load and resistance factors can be determined for the assessment applying simple AFOSM.An approximation method to determine the factor is proposed, and numerical example shows that the target reliability level can be achieved fairly accurately using an approximate reduction factor.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, generally non-linear optimization problem must be solved. The approximation 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 optimization can be simplified avoiding time-dependent reliability analysis. Less

基础设施恶化是许多国家普遍存在的问题。为了评估此类结构的未来持续使用情况，需要开发简单实用的工具来评估结构随时间变化的可靠性和性能。当多个时变载荷作用在结构上时，需要考虑参考期内组合的最大强度。该项目首先提出了组合最大强度的累积分布函数（cdf）的理论表达式。数值例子表明，无论负载强度和随机过程的统计特性如何，cdf的理论表达式都提供了相当好的估计。然后引入了由于部件退化而导致的电阻减小因子的概念，将与时间相关的可靠性问题近似为与时间无关的可靠性问题。利用该因子，时变电阻可以等效为时不变电阻，并且可以确定负载和电阻因子，以便应用简单的 AFOSM 进行评估。提出了一种确定该因子的近似方法，数值示例表明，使用近似折减因子可以相当准确地实现目标可靠性水平。定期在役检查和适当的维护可以恢复退化的结构 组件接近原始状态。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。为了设计最佳的检查/维护策略，通常必须解决非线性优化问题。可以应用近似方法来估计电阻减小系数，包括当部件的强度由于例如恢复而随时间不连续变化时的情况。使用所提出的方法，可以简化优化，避免依赖时间的可靠性分析。较少的

项目成果

M.Nonaka, Y.Mori, & Y.Funahashi.: "A Study on LRFD Taking Structural Degradation into Account"Summary of Technical Papers of Annual Meeting, AIJ. B-I. 19-20 (2000)

M.野中，Y.森，

Yasuhiro Mori & Kazuko Murai: "Load and resistance factors taking combined load processes into account"Proc.8th Int.Conf.on Applications of Statistics and Probability. 973-980 (1999)

森泰弘

野中桃子,森保宏,舟橋洋祐: "構造部材の耐力劣化を考慮した荷重・耐力係数設計法"日本建築学会大会学術講演梗概集. B-I. 19-20 (2000)

Momoko Nonaka、Hiroshi Mori、Yosuke Funahashi：“考虑结构构件强度恶化的载荷和强度系数设计方法”日本建筑学会会议学术讲座摘要 19-20 (2000)。

M.Nonaka, Y Mori, K.Baba, & Y.Funahashi.: "A Study on LRFD for Structural Component Taking its Strength Degradation into Account"Proc. AIJ Tokai Chapter Archiectural Research Meeting, AIJ. No.38. 133-136 (2000)

M.Nonaka、Y Mori、K.Baba、

Y.Mori & M.Nonaka: "A Study on Load and Resistance Factor Design for Degrading Structural Component"Proc.3rd Japan Conference on Structural Safety and Reliability. Vol.4. 603-608 (2000)

森勇