Feasibility and performance of novel tapered iron bolt shear connectors in demountable composite beams

Abstract

The performance of tapered iron bolt (TIB) shear connectors and their feasibility to be used in demountable composite beams are investigated in this study. The typical TIB shear connector consists of six components, i.e., a connecting bolt, conical iron plug, top covering plate, top fixing bolt, retaining washer and inner sleeve. The connectors are expected to 1) reduce the initial slip between the concrete slab and steel beam, which generally exists for steel-concrete composite beams using bolted shear connectors, and 2) be capable of being replaced for composite beams in-situ without damaging other components. Two series of pushout tests were conducted on the specimens with TIB shear connectors in accordance with Eurocode 4 (EC4). The demountability of TIB shear connectors after severe corrosion induced by accelerated corrosion, i.e., wet-dry cycles, was examined. All pushout test specimens failed in shear fracture at the bolts while the concrete slabs remained undamaged. The test results demonstrated that the replacement of TIB connectors would not affect the failure mode of TIB connectors but have a moderate influence on the shear capacity. Therefore, a reduction factor was proposed to account for the influence of replacement in design. The design equations of TIB shear connectors under bolt shear and local concrete failure were proposed. The proposed design method is able to provide a reasonably accurate prediction for the failure mode and shear strength of the TIB connectors.