Flexural performance of prefabricated FRP-concrete hybrid beam with in-situ-cast UHPC pockets

Abstract

In this study, a novel prefabricated fiber reinforced polymer (FRP)-concrete hybrid beam (HB) was proposed with the aim of reducing initial material costs and expediting construction. The proposed HB features a precast concrete slab and in-situ cast ultra-high performance concrete (UHPC) pockets around bolted connections. A comparison was made between one FRP-concrete HB with a normal concrete slab and four proposed FRP-concrete HBs with UHPC pockets through flexural testing. The results showed that the proposed bolted shear connection in UHPC pockets significantly reduced interfacial slip and increased the flexural rigidity of the HBs when compared to the FRP-concrete HB. The use of continuous UHPC pockets in the HB resulted in substantial improvements in ultimate loading capacity, with an increase between 14.2% and 40.4% compared to the traditional in-situ cast FRP-concrete HB. Continuous UHPC pockets results in higher ultimate loading capacity than that of discontinuous UHPC pockets HB. The HBs with normal concrete or discontinuous UHPC pockets failed due to concrete crushing, while the continuous UHPC pockets HB failed at shear fracture of the FRP webs. Only slight slippage (less than 0.2 mm) was observed at the FRP-concrete interface.