Abstract
In recent years, the development and application of high performance fiber reinforced concrete or cementitious composites are increasing due to their high ductility and energy absorption characteristics. However, it is difficult to obtain the required properties of the FRCC by simply adding fiber to the concrete matrix. Many researchers are paying attention to fiber reinforced polymers (FRP) for the reinforcement of construction structures because of their significant advantages over high strain rates. However, the actual FRP products are skill-dependent, and the quality may not be uniform. Therefore, in this study, two-way punching tests were carried out to evaluate the performances of FRP strengthened and steel and polyvinyl alcohol (PVA) fiber reinforced concrete specimens for impact and static loads. The FRP reinforced normal concrete (NC), steel fiber reinforced concrete (SFRC), and PVA FRCC specimens showed twice the amount of enhanced dissipated energy (total energy) under impact loadings than the non-retrofitted specimens. In the low-velocity impact test of the two-way NC specimens strengthened by FRPs, the total dissipated energy increased by 4 to 5 times greater than the plain NC series. For the two-way specimens, the total energy increased by 217% between the non-retrofitted SFRC and NC specimens. The total dissipated energy of the CFRP retrofitted SFRC was twice greater than that of the plain SFRC series. The PVA FRCC specimens showed 4 times greater dissipated energy than for the energy of the plain NC specimens. For the penetration of two-way specimens with fibers, the Hughes formula considering the tensile strength of concrete was a better predictor than other empirical formulae.
Highlights
The addition of fiber reinforcement is one of the most effective methods for enhancing the performance of concrete [1] [2] [3]
The loads of steel fiber reinforced concrete (SFRC)-N specimens gradually increased, and the specimens reinforced with carbon fiber reinforced polymer (CFRP) showed strain softening after the maximum loads
Punching tests were performed in order to observe the behaviors of fiber reinforced polymer (FRP) strengthened and fiber reinforced concrete specimens for quasi-static and low-velocity impact loads by using the universal testing machine (UTM) and drop weight testing machine
Summary
The addition of fiber reinforcement is one of the most effective methods for enhancing the performance of concrete [1] [2] [3]. As shown, more than two types of fibers are used simultaneously to control micro cracks and macro cracks. This requires complex compounding processes, which can lead to entanglement or lack of uniform distribution of fibers in the matrices. The ACI 440 assumes only two failure modes for design calculations: compressive failure of the concrete and failure of the FRP strengthening system [12] [13].
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