The purpose of this study was to investigate the influence of fiber reinforcement on the shear capacity of reinforced concrete (RC) beams. Both steel and synthetic fibers at variable volume fractions were investigated. Two series of tests were performed: structural tests, where RC beams were tested to failure under an applied four-point load; and materials tests, where companion fiber-reinforced concrete (FRC) prisms were tested under direct shear to obtain material properties such as shear strength and shear toughness. FRC test results indicated an almost linear increase in the shear strength of concrete with an increase in the fiber volume fraction. Fiber reinforcement enhanced the shear load capacity and shear deformation capacity of RC beams, but 1% fiber volume fraction was seen as optimal; no benefits were noted when the fiber volume fraction was increased beyond 1%. Finally, an equation is proposed to predict the shear capacity of RC beams.Key words: shear strength, fiber-reinforced concrete, RC beam, stirrups, energy absorption capacity, steel fiber, synthetic fiber.

A novel method of testing reinforced concrete beams under impact using a drop tower is described. The method consists of configuring the support conditions and instrumenting both the loading end of the hammer and support points in such a way that a proper dynamic analysis of the impact event can be performed and rational data can be derived.

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During dynamic events (such as impact forces), structures fail to absorb the incoming energy and catastrophic collapse may occur. Impact and quasi-static tests were carried out on reinforced concrete beams with and without externally bounded sprayed and fabric glass fiber-reinforced polymers. For impact loading, a fully instrumented drop-weight impact machine with a capacity of 14.5 kJ was used. The drop height and loading rate were varied. The load-carrying capacity of reinforced concrete beams under impact loading was obtained using instrumented anvil supports (by summing the support reactions). In quasi-static loading conditions, the beams were tested in three-point loading using a Baldwin Universal Testing Machine. ABAQUS FEA software was used to model some of the tested reinforced concrete beams. It was shown that the stiffness of reinforced concrete beams decreases with increasing drop height. It was also shown that applying sprayed glass fiber-reinforced polymers (with and without mechanical stiffeners) and fabric glass fiber-reinforced polymers on the surface of reinforced concrete beams increased the stiffness. Results obtained from the software analyses were in good agreement with the laboratory test results.

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