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

Abstract

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.

Collision Capacity Evaluation of RC Columns by Impact Simulation and Probabilistic Evaluation

“…However, due to the inherent time-dependent characteristics of impact loading, it is difficult to properly obtain precise data regarding structural behavior from impact tests (Nam et al 2009a). In particular, the multiple experiments required for parametric studies to obtain sufficient data for structural design purposes are too costly and difficult; therefore, the only feasible means to obtain a wide variety of data are precise impact simulation analyses.…”

“…Research on concrete structural behavior under impact loading is being actively pursued worldwide (Ferrer et al 2010;Nam et al 2009aNam et al , 2009bNam et al , 2010. However, due to the inherent time-dependent characteristics of impact loading, it is difficult to properly obtain precise data regarding structural behavior from impact tests (Nam et al 2009a).…”

“…Recently, due to increasing construction of roads and other transportation-related infrastructures as well as increasing traffic in urban areas, collisions between speeding vehicles and structural columns and walls have increased dramatically (Ferrer et al 2010;Nam et al 2009a;Nam et al 2010;Tian et al 2011). Also, the 9/11 terror attack on the World Trade Center, which caused a total collapse, led to intense public concern about structural collapse from sudden impact or blast loading (Nam et al 2009b;Englekirk 2005).…”

“…Therefore, the transient impact characteristic or high strain rate effect must be properly considered in the design using precise impact simulation results. However, the degree of damage caused to a column by an impact load is rarely calculated precisely, because few designers carry out a suitable impact analysis using explicit finite element analysis (FEA) (Nam et al 2009a;Sastranegara et al 2005; To more accurately predict the effect of an impact on columns, impact resistance capacity must be determined using high strain rate and explicit FEA programs such as LS-DYNA to simulate structural behavior under impact loading. Also, because of the difficulty of capturing the instantaneous column behavior from an impact experiment, analytical data obtained from precise FEA simulations are needed for impact damage characterization and resistance capacity evaluation from a probabilistic point of view (Harries and McNeice 2006;Jain et al 2001).…”

Performance of frp-retrofitted concrete bridge columns under blast loading

“…Most studies in this area apply analytical simulations. Current analytical work in blast loading mostly applies 3-D complex FE modeling schemes, accuracy of which depends greatly on the fi neness of the mesh, which in turn leads to signifi cantly high computational cost [13][14][15].…”