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

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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.**