Experimental evaluation of a novel demountable shear connection system in prefabricated steel-concrete composite beams

Unlike traditional studies focused on developing demountable shear connectors for prefabricated steel-concrete composite structures, this paper introduces a novel demountable shear connection system that replaces cement- based fillers with steel shot particles. The proposed system consists of a partially-threaded no-headed stud (PTNHS), two washers of different diameters, a cup-shaped steel tube, and steel shot particles. Using steel shot particles as filler eliminates the need for curing under specific time and temperature conditions, thereby reducing traffic interruptions. This research conducts a preliminary push-out test to investigate the mechanical behavior of the proposed system and evaluate its installation and disassembly procedures. Experimental results revealed that specimens failed due to shear except two specimens failed due to welding defects. The fracture surfaces of the PTNHS shear connectors were located above the weld collar. Only localized concrete crushing was observed in precast concrete slabs. The load-slip curves of PTNHS shear connectors within the same specimen exhibited similar patterns. The maximum average shear stiffnesses of PTNHS shear connectors was only 27.2 % of headed studs shear connectors. The slip of all specimens at the peak load exceeded 6 mm. Adding a 5 mm thick washer with a larger-diameter significantly improved shear stiffness but had no effect on shear capacity. Mixing steel shot particles with resin increased shear capacity but reduced shear stiffness. The average ultimate load of PFSSC-19(16) specimens was 12.7 % and 15.1 % lower than that of bolted shear connectors and headed stud shear connectors, respectively. However, the average ultimate loads of PTNHS shear connectors with a 22 mm diameter were only about two-thirds of headed stud shear connector. Finally, it was found that the shear capacities of PTNHS shear connectors calculated using China code GB50017 were in good agreement with the experimental results.