Fire-Exposed Reinforced Concrete Frames: Structural Performance, Progressive Collapse Assessment and Retrofit Strategy

世界贸易中心塔楼的倒塌和许多记录在案的火灾引发的结构故障引起了人们对公共安全的严重关切。大多数钢筋混凝土（RC）结构的设计使用规定的防火设计方法，是基于暴露于标准火灾的RC元件的结构测试。然而，它们具有显着的缺点，包括：结构层面的安全裕度不确定、对连续倒塌的抵抗力未知以及不适用于考虑复杂的自然火灾现象所需的创新成本节约解决方案。它们也未能提供必要的指导，以评估和改造火灾损坏的结构。设计标准正在发生革命性的变化，具体规定了可接受的性能标准或设计目标，以允许工程创新。这场革命正在导致建筑师和结构工程师之间的消防安全责任平衡发生重大转变，他们需要开发必要的专业知识并配备正确的分析工具。这些工具应能加快设计过程，以便证明与额外工程相关的效益。申请人的研究小组最近开发并验证了用于分析和设计暴露于标准火灾的RC框架的简化方法和工具。这些为研究人员和工程师提供了必要的手段来了解火灾下复杂的结构行为，设计RC框架以满足特定的安全目标，并验证商业计算机程序的分析结果。拟议的研究将进一步发展申请人的方法和工具，使其适用于自然火灾的情况。它们的使用将允许新结构的基于性能的设计，并提供评估火灾损坏结构的安全性的手段，考虑到连续倒塌的可能性。这种评估对于在改装之前就是否需要疏散作出关键决定至关重要。应急响应小组迫切需要这些工具来持续监测火灾暴露结构的状况，以保证其人员的安全。该研究还将提供工具，为火灾损坏的钢筋混凝土框架设计改造技术，以保证公共安全。拟议的研究将利用独特的消防设施在兰顿学院的消防与公共安全卓越中心暴露钢筋混凝土元件火灾之前，测试他们在西方的结构实验室。测试结果将导致开发和验证上述工具。6名HQP和25名本科生将体验独特的测试程序，包括与来自Western和兰顿的技术人员的互动，并将培养加拿大和全球结构工程专业急需的分析技能。

The collapse of the towers of the World Trade Center and the many documented fire-initiated structural failures raise grave concerns about public safety. The majority of Reinforced Concrete (RC) structures are designed using prescriptive fire design approaches that are based on structural tests of RC elements exposed to standard fires. However, they possess significant drawbacks including: undefined safety margin at the structure level, unknown resistance to progressive collapse and inapplicability to consider innovative cost-saving solutions demanded by the complex natural fire phenomena. They also fail to provide the needed guidance to evaluate and retrofit fire-damaged structures.***Design standards are being revolutionized by specifying acceptable performance criteria or design objectives to allow for engineering innovations. This revolution is causing a major shift in the balance of responsibility for fire safety between the architect and the structural engineer who needs to develop the necessary expertise and be equipped with the right analytical tools. These tools should expedite the design process allowing for the justification of the benefits associated with the additional engineering work.***The Applicant's research group has recently developed and validated simplified methods and tools to analyze and design RC frames exposed to standard fire. These provide researchers and engineers with the necessary means to understand the complicated structural behaviour under fire exposure, to design RC frames to satisfy specific safety objectives and to validate analysis results from commercial computer programs.***The proposed research will further develop the Applicant's methods and tools to make them suitable for cases of natural fire. Their use will allow for performance-based design of new structures and provide means to assess the safety of fire-damaged structures considering the potential of progressive collapse. Such assessment is essential to make critical decisions about the need for evacuation prior to retrofitting. Emergency response teams are in desperate need of such tools to continuously monitor the condition of fire-exposed structures to guarantee the safety of their personnel. The research will also provide tools to design retrofitting techniques for fire-damaged RC frames that guarantee public safety.***The proposed research will utilize the unique fire facility at Lambton College's Fire & Public Safety Centre of Excellence to expose RC elements to fire before testing them at Western's Structures Lab. Test results will lead to the development and validation of the above-mentioned tools. 6 HQPs and 25 Undergraduate students will experience unique testing procedures involving interaction with technicians from Western and Lambton, and will develop analytical skills that are much needed within the structural engineering profession in Canada and worldwide.**