Use of fiber-reinforced plastics versus steel for shear reinforcement of concrete

The use of fiber-reinforced plastics (FRPs) for the reinforcement of concrete structures is receiving much attention at present. Attempts are being made to better understand the behavior of concrete containing these fibrous materials. Much of this work, however, is aimed at attempting to fit present design guidelines to this wholly new construction material. This paper presents pushoff tests and suggests analytical techniques for the shear capacity of concrete reinforced with FRPs. As a basis for comparison, tests on specimens containing steel stirrups are also presented. It is shown that while plasticity theory may be considered appropriate for use in the steel-reinforced situation, other analysis techniques are required for FRP-reinforced specimens. This is because the brittle nature of the new materials makes them susceptible to localized stress concentrations, which means that bond characteristics of these materials are particularly important. It is concluded that the choice of an appropriate analysis technique depends on the amount of debonding that FRPs are able to undergo during shear collapse of the concrete structure.