Push-out tests on headed studs and lattice shear connectors welded to louver steel plate

Abstract

In this experimental study, push-out tests were performed to evaluate the shear strength of louver steel plates, which were combined with two types of shear connectors to ensure structural integrity between the precast and cast-in-place concrete. In total, 18 test specimens were prepared, and the type of shear connectors, the presence/absence reinforcement of the middle concrete block, and the type and thickness of the steel plates were selected as the main variables in this experimental programs. The tests revealed that when the middle concrete block was not reinforced, the measured peak shear strength (Vp) of the headed studs was slightly smaller than the shear strength (VAISC) predicted by the equation in AISC, as the middle concrete block failed. Meanwhile, Vp of the unreinforced specimen with a combination of headed studs and louver steel plates was 1.65 times larger than Vp of the unreinforced specimens with a combination of headed studs and plain steel plates. This result confirms that louver steel plates contributed to an increase in shear strength; namely, the increased strength resulting from the louver steel plates was approximately 88 % of the theoretical bearing strength of the louvers. Vp of the headed studs was higher than VAISC regardless of the thickness of the louver steel plates, but Vp of the lattice shear connectors was higher than VAISC only when a steel plate with a thickness of 3.0 mm was used. In terms of the slip capacity, while the headed studs satisfied the slip capacity specified in Eurocode 4, the lattice shear connectors did not satisfy this criterion, owing to an insufficient welding length.