Connections in GFRP reinforced precast concrete frames

Abstract

Glass fiber reinforced polymer (GFRP) is an effective alternative reinforcing solution to tackle problems associated with steel corrosion in reinforced concrete structures located in harsh environments. However, there are multiple construction challenges when cast-in-place GFRP reinforced concrete is used. Cast-in-place concrete is both labor and time intensive on account of timely assembly of falsework and formwork as well as pouring and curing of concrete. To avoid such challenges and accelerate the construction process, GFRP reinforced precast concrete elements can be used to avoid corrosion problems, improve the quality of the construction and reduce the associated risk and total cost. While GFRP reinforced precast concrete elements exhibit behavior comparable to those reinforced with steel, research on connections between precast elements is limited. This study aims to investigate the performance of bent cap connections for GFRP precast concrete elements for applications in bridge and jetty structures. An experimental investigation was designed and conducted on a large-scale concrete frame constructed out of GFRP reinforced precast concrete elements with four different types of pocketless connections. The effectiveness of using epoxy resin rather than conventional cement grout to accelerate the construction process was investigated. Also investigated were the effect of pre-stressing, the number of connecting reinforcement elements, and the type of reinforcement (i.e. bars and bolts). The frame was subjected to cyclic lateral loading and was tested in two stages. Results and discussion on the general behavior, failure modes, energy dissipation, damping ratio and ductility were presented. The results of the pocketless test frame were also compared with a similar frame tested previously by the same research group where pocket connections were used to transfer moment between the beam and column members. The results showed that using connecting bars/bolts in pocketless connections outperform the behavior of pocket connections. This study concluded that avoiding pockets and providing the integrity of the beam-column joint through bolt/bar connection can improve the general performance of the beam-column connection compared to connections with pockets. This method also increases the speed of construction and simplifies the manufacturing procedure.