Performance of Ultra High Performance Fiber Reinforced Concrete Elements Subjected to Extreme Blast Loads

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Due to increased threats it is becoming important to ensure that strategic buildings in Canadian cities are blast resistant. There is a need to develop innovative and cost-effective methods that can ensure acceptable performance during blast events. Recent developments in material science have led to a new generation of Ultra High Performance Fibre Reinforced Concretes (UHP-FRC). When compared to conventional concrete UHP-FRC shows very high compressive strength, improved tensile strength, post-cracking resistance and toughness, making UHP-FRC an ideal material for use in the design of blast resistant structures. In ground-story columns, UHP-FRC can be used to improve performance and prevent progressive collapse. Moreover the improved properties of UHP-FRC can allow for relaxed detailing leading to improved constructability. Superior toughness and fragmentation resistance can also allow for the use of UHP-FRC in the design of optimized blast-resistant walls that can be used as part of an effective blast protection system for buildings of critical importance. The overarching aim of the proposed research is to mitigate hazards associated with blast loads on building structures using UHP-FRC structural systems. The long-term aims also include the development of design and detailing procedures for the use of UHP-FRC in the blast-resistant design of structures. Short-term the program will focus on the blast performance of UHP-FRC building columns and wall components. To assess blast performance of columns half-scale specimens will be subjected to simulated blast loading using the state-of-art shock-tube facility at the University of Ottawa. The columns will be subjected to a variety of blast pressure combinations aimed at testing the columns at elastic, yield and ultimate conditions. Similarly, shock-tube testing will also be conducted on UHP-FRC wall panels. Test variables will include UHP-FRC material properties, flexural and transverse steel reinforcement properties (ratio and strength) . As part of the analytical program, material models for UHP-FRC which incorporate dynamic effects will be developed based on extensive material testing on small-scale specimens tested under variable strain-rates, and procedures for the dynamic analysis of UHP-FRC columns and walls subjected to blast will be assessed and validated. This research program will result in innovative experimental and analytical research on the blast performance of UHP-FRC components and will provide the engineering and research community with important data and research findings. Six graduate students will be training and HQP trained in this program will meet increased demand for engineers that are well-versed in blast resistant design of buildings in Canada. The program will be a first step towards development of CSA S850 blast design guidelines for UHP-FRC, leading to improved safety and security for Canadians.