Cyclic Behavior of Beam-Column Pocket Connections in GFRP-Reinforced Precast Concrete Assemblages

This paper presents details of an experimental program evaluating the behavior of six half-scale glass fiber-reinforced polymer (GFRP) reinforced concrete beam-column precast members connected together through pocket connections, which are subjected to cyclic loading. The novel beam-column connection was constructed by incorporating either epoxy resin or tensioned or untensioned GFRP rock bolts in conjunction with different-sized pocket connections. The effects of an additional connection bar between the column and beam components in the connection, as well as the confinement of the concrete around the pocket region, were also investigated. An innovative test setup was designed so that the beam-column joint could rotate without restraint provided by the supports. All specimens were tested under an incrementally increasing cyclic load. The load-carrying capacity, deformational behavior, failure modes, energy dissipation, and hysteretic damping were all recorded and evaluated. All specimens failed as a result of column failure within the pocket connection region. This was attributed to the relative rotational flexibility of the column with respect to the beam, owing to the low elasticity of the epoxy resin used in the pocket region, and hence the stress concentration at the column ends within the pocket area. According to the results, a pocket connection containing GFRP reinforcement providing confinement around the embedded area yielded the highest capacity, ductility, and energy dissipation under cyclic loading. The connection containing a GFRP bolt, regardless of whether or not the bolt was prestressed, did not significantly improve the performance of the connection. The findings presented here can be used for the design of precast elements reinforced with GFRP bars. Of particular relevance is application to jetties and other offshore concrete infrastructure where steel reinforcement (because of corrosion issues) needs to be replaced with GFRP reinforcement.