Advanced Modeling of Blast Response of Reinforced Concrete Walls with and without FRP Retrofit

Presented by Tarek H. Kewaisy, Louis Berger; and Ahmed Khalil, Applied Science International, LLC For decades, protective design professionals have specified Reinforced Concrete (RC) as the construction material of choice to provide the necessary protection to military and civilian structures that may be exposed to blast effects. Nevertheless, in recent years RC has been facing new challenges to provide higher levels of protection due to the increasing scope and size of potential explosive threats and the vulnerabilities of newly included targets to be protected. To address this challenge, this research investigates the effectiveness of Fiber Reinforced Polymers (FRP) as a viable retrofit technique to improve the blast resistance of RC elements. The current work focuses on predicting the dynamic responses of one-way RC slabs constructed of various materials with and without the FRP retrofit when subjected to high levels of blast loading using an innovative numerical simulation technique. Experimental responses of unretrofitted one-way reinforced concrete slab specimens having two strength classes (i.e. Normal and High) were obtained from a testing program sponsored by the NSF, managed by ACI-447 and UMKC/ SCE and completed at the Blast Loading Simulator (BLS) at the ERDC/ USACE, Vicksburg, MS. Our investigation utilized the Applied Element Method (AEM) implemented in the Extreme Loading for Structures software (ELS) to simulate the nonlinear dynamic responses and to predict the failure patterns for both unretrofitted and FRP retrofitted cases. Maximum and residual displacement responses and cracking patterns obtained from ELS were compared to simulation results predicted by LS-DYNA and to recorded test measurements.