Experimental study on shear performance of an advanced bolted connection in steel-concrete composite beams

Compared to traditional shear keys, bolted shear connections adopted in steel-concrete composite beams or bridges provide the advantages of improved construction efficiency and rapid replacement of the deteriorated elements. However, current investigations on the shear performance of bolted shear connectors are quite limited. This paper explores the mechanical behavior of the advanced bolted shear connections embedded in steel and concrete composite beams. A total of 10 push-off test specimens were fabricated and carried out to determine the bolt diameter and the bolt pretension on the failure models, shear strength, initial slip load, shear stiffness, and peak slip of this advanced bolted shear connection. The experimental results demonstrate that bolt sheared off is the primary failure mode in all specimens with a small amount of concrete crushing underneath the bolts. Bolt pretension displays a negligible effect on the shear keys' failure models and the shear capacity, while the concrete spalling area increases as the bolt diameter improves. The initial slip load and the shear stiffness of the advanced bolted shear connections grow as the bolt pretension and bolt diameter increase. Based upon the existing formulae, some design recommendations are proposed for predicting this advanced bolted shear connection.