Development of Minimum Life-Cycle cost Design Criteria

制定最低生命周期成本设计标准

• 批准号: 9510243
• 负责人: Y. Wen
• 金额: $ 16.86万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-01 至 1999-02-28
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9510243&HistoricalAwards=false
• 关键词: Development; Minimum; Life; Cycle; cost

9510243 Wen Design procedures for civil infrastructure systems under environmental loadings have gradually changed from largely judgments/experience-based, semi- probabilistic, to probabilistic. Procedures based on optimization of long-term risk and benefit, however, have not been developed. Such a procedure is specially needed in evaluation and repair/retrofit of existing facilities whose hazard exposure time is short but whose failure may still cause serious consequences. A large number of the nation's civil infrastructure systems are aging and many are in need of replacement. The repair/retrofit problem will become more acute. Rational life-cycle cost based design criteria are needed in which effects of loading and resistance uncertainty, hazard exposure time, costs of consequence of failure and operation and maintenance, and discount of cost/loss over time are all taken into consideration. The objectives of this project are: (l) development of methodology for determination of design criteria based on life-cycle and (2) application to new and retrofitted facilities not covered by regular codes an standards. The problem is formulated as that of minimization of expected total life-cycle cost with respect to the design variables, i.e., design loads and resistance of the facility or corresponding load and resistance factors in a LRFD format. The required research tasks are to: (1) formulate the design as a constrained minimization problem considering uncertainties in the load and resistance including random load occurrence time, intensity, and correlation, costs of failure consequences, and discounting cost/loss over time; (2) develop of optimization algorithm for solution; (3) study the effect of load and resistance uncertainty and resistance deterioration over time; (4) model cost functions and examine sensitivity of design and (5) determine the design loads. The research will impact the development of new concepts and metho dologies of design that have important implications in the next generation codes and standards. The results will also have more immediate benefit in development of guidelines for repair/retrofit. ***

9510243 温 环境荷载下的民用基础设施系统的设计程序已逐渐从主要基于判断/经验、半概率变为概率。 然而，基于长期风险和收益优化的程序尚未制定。 对于危险暴露时间短但故障仍可能造成严重后果的现有设施的评估和维修/改造特别需要这样的程序。 国家大量民用基础设施系统正在老化，许多需要更换。 维修/改造问题将变得更加严重。 需要基于合理的生命周期成本的设计标准，其中考虑了负载和阻力不确定性的影响、危险暴露时间、故障和操作和维护后果的成本，以及随着时间的推移成本/损失的折扣。 该项目的目标是：(l) 开发根据生命周期确定设计标准的方法；(2) 适用于常规规范和标准未涵盖的新建和改造设施。 该问题被表述为相对于设计变量（即设施的设计载荷和阻力或 LRFD 格式中的相应载荷和阻力系数）最小化预期总生命周期成本的问题。 所需的研究任务是：（1）将设计制定为一个约束最小化问题，考虑载荷和阻力的不确定性，包括随机载荷发生时间、强度和相关性、故障后果的成本以及随着时间的推移贴现成本/损失； (2) 求解优化算法的开发； (3) 研究负载和电阻不确定性以及电阻随时间恶化的影响； (4) 建立成本函数模型并检查设计的敏感性；(5) 确定设计载荷。 该研究将影响新概念和设计方法的发展，这些概念和方法对下一代规范和标准具有重要影响。 结果还将对制定维修/改造指南产生更直接的好处。 ***