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Abstract
A novel configuration of a hybrid fibre reinforced polymer (FRP) composite-concrete beam is presented. The beam consists of a glass fibre reinforced polymer (GFRP) pultruded profile, a carbon fibre reinforced polymer (CFRP) laminate and a concrete block all wrapped together using filament winding. The major feature of this design is that it does not mimic that of reinforced concrete as reported previously. The CFRP laminate is not designed to fail first to serve as a warning of imminent failure, but rather to enhance the stiffness of the beam by compensating for the lack of stiffness of the GFRP profile. The external filament winding ensures composite action between the concrete and the pultruded profile.
The experimental results have shown that this approach is successful. The wrapping did not only eliminate the risk of premature failure as a result of the concrete block debonding from the pultruded profile, but it was also found to enhance the stiffness and load carrying ability of the beams.
Using finite element analysis, it was revealed that, through partial confinement, the filament-wound wrapping shift the behaviour of the concrete from brittle to ductile, thus providing the beam with more energy dissipative properties. Yet, the amount of this energy dissipative behaviour was also found to depend on the thickness of the concrete block. When the latter is too thin, failure akin to shear punching appears to take place. A shear punching failure model was hence developed and used to estimate the minimum thickness of the concrete block required to achieve the ductile failure required for civil engineering structures.