Condition-based risk assessment and management for infrastructure retrofit in the face of uncertainty

社会生活和经济增长严重依赖关键基础设施系统，加拿大的资产价值约为1.1万亿美元。然而，根据2016年加拿大基础设施报告卡，由于激进的环境攻击(例如腐蚀)和反复发生的低或中等强度危险事件(例如地震)，这些基础设施资产中有35%处于一般、较差或非常差的状况。这种退化的形式是结构/材料的逐渐退化和基于冲击的物理损伤，降低了工程结构的性能。考虑到在极端危险事件中，现有基础设施系统的失效或丧失功能可能会造成毁灭性的生命安全和经济后果，因此近年来，对现有基础设施系统进行基于状态的风险评估和管理(例如，通过优化改造)已成为一种迫切需要。*拟议研究计划的目标是在面对不确定性的情况下，为“第二代”改造战略开发一个基于状态的风险评估和管理(CRAM)框架。这一框架结合了受灾害或年龄影响的基础设施系统的状况识别(即以概率方式估计当前状态)、考虑了相关不确定性来源的风险评估以及风险管理的风险知情优化改造设计。状态识别和风险评估将提供有关翻新的信息，并将开发一种统一的风险信息优化的翻新或维修设计方法，以帮助提高结构性能。*这项拟议的研究计划将侧重于现有的基础设施，如桥梁和遭受地震危害的建筑物。这四个目标或主题是开发(A)具有退化特性的工程结构的详细非线性有限元(FE)模型；(B)用于状态识别的非线性有限元模型更新技术；(C)用于风险评估的不确定性传播工具，包括模型参数不确定性；以及(D)用于面对不确定性的风险缓解的统一优化改造方法。该项目的成功成果将达到长期研究计划的里程碑，该计划旨在将CRAM框架扩展和应用到广泛的工程风险问题，为社会提供风险管理解决方案。

The societal living and economic growth rely heavily on critical infrastructural systems, with the assets value of about $1.1 trillion in Canada. However, according to the 2016 Canadian Infrastructure Report Card, 35% of those infrastructure assets are in fair, poor or very poor condition, due to aggressive environmental attacks (e.g., corrosion) and recurring low- or moderate-intensity hazard events (e.g., earthquakes). The degradation, in the form of progressive structural/material deteriorations and shock-based physical damage, reduces the performance of engineering structures. In recognition of devastating life safety and economic consequences potentially caused by their failure or loss of functionality in extreme hazard events, the condition-based risk assessment and management (e.g., through optimum retrofit) of existing infrastructure systems has become an emergent need in recent years.******The goal of the proposed research program is to develop a condition-based risk assessment and management (CRAM) framework for the “second-generation” retrofit strategy in the face of uncertainty. This framework integrates condition identification (i.e., estimating the current state probabilistically) of the hazard- or age-affected infrastructure systems, risk assessment with pertinent sources of uncertainty considered, and risk-informed optimum retrofit design for risk management. The condition identification and risk assessment will provide information on retrofit, and a unified risk-informed retrofit or repair design approach using optimization will be developed to aid in enhancing the structural performance.******This proposed research program will focus on existing infrastructure such as bridges and buildings subjected to seismic hazard. The four aims or themes are developing (A) detailed nonlinear finite element (FE) models of engineering structures with degrading properties; (B) nonlinear FE model updating techniques used for condition identification; (C) an uncertainty propagation tool for risk assessment accounting for pertinent uncertainties including model parameter uncertainty; and (D) a unified optimum retrofit approach used for risk-mitigation in the face of uncertainty. The successful outcome of this project will reach a milestone in the long-term research program on extending and applying the CRAM framework to a wide range of engineering risk problems, providing society with risk management solutions.