Analytical Study of Finite Element Models for FRP Retrofitted Concrete Structure under Blast Loads

Fiber reinforced polymer (FRP) is one of the best retrofitting materials for blast resistance strengthening due to a number of advantages, such as excellent strength to self-weight ratio, large fatigue resistance capacity, etc. Presently, many different types of FRP models are used in blast analysis, but they are used randomly without fundamental scientific reasoning, thereby creating erroneous analytical results. Therefore, this study is carried out to assess and to compare a comprehensive finite element analytical model of FRP that can properly consider the properties of FRP as a retrofit material. After reviewing available FRP models currently used by researchers in the field, four analytical FRP models are selected to assess the behavior of FRP sheet and FRP retrofitted concrete structure; isotropic linear elastic shell element model (IES model), orthotropic linear elastic shell element without shear deformation model (OES model), orthotropic linear elastic shell element with shear deformation model (OESS model), and linear elastic beam element model (EB model). Using the selected FRP models, noise analysis of FRP sheet and FRP retrofitted concrete is carried out to confirm mesh sensitivity for convergence. In addition, finite element analysis of FRP retrofitted RC slab under blast load is performed to select the most appropriate FRP model and to validate the blast analysis technique. All of the analysis results for four selected FRP models are compared to verify and select the optimum model. Finally, a discussion about the study results with respect to code response criteria is presented.