Enhancement of the impact resistance of masonry walls using fiber-reinforced polymer composites

Abstract

Many civilian structures are masonry ones. However, masonry walls are susceptible to impact loading. Despite the vulnerability, research on enhancing the impact resistance of masonry walls is substantially scarce, especially under high-velocity impact. Hence, in this study, the effect of fiber-reinforced polymer (FRP) composites on the impact resistance of masonry walls was numerically investigated, especially considering high-velocity impact loading. For this purpose, finite element analysis (FEA) was implemented deploying LS-DYNA. In modeling, the Add Erosion and the Smooth Particle Hydrodynamics options were employed to effectively represent impact behaviors of masonry walls subject high-velocity impact loading. Firstly, the developed masonry wall models were validated by comparing the numerical results with experimental ones. Using the verified numerical models, various parametric studies were performed. The main parameters were the directions and types of fiber, different velocities of an impactor, and the number of impactors. Based on the study, the near-surface-mounted (NSM) FRP method was found to be inefficient in improving the impact resistance of masonry walls. Although the externally-bonded (EB) FRP technique was more effective than the NSM FRP one, the impact behavior varied depending on the types and number of FRP. For instance, strengthening a masonry wall using one layer of high-modulus carbon FRP (HCFRP) EB sheet resulted in the perforation of the HCFRP sheet due to the low ultimate strain of HCFRP sheet. Although one layer of standard CFRP (SCFRP) EB sheet was effective to prevent a masonry wall from being perforated against one impactor, the strengthened masonry wall was penetrated by multiple impactors. It was found that two woven SCFRP EB sheets were optimum to evade the perforation of masonry walls subject to high-velocity impact loading. Furthermore, equations for correlations between the maximum impact force and impact energy are proposed.