Experimental study on shear behavior of high strength bolt connection in prefabricated steel-concrete composite beam

Abstract In order to study the shear behavior of high strength bolt connections in a prefabricated steel-concrete composite beam, eleven push-out specimens with different parameters were tested. In the tests, two failure modes of the specimens were observed. For the specimens with the concrete strength of higher than 50 MPa and the bolt diameter of smaller than 20 mm, the bolts failed in a shear fracture. For the other specimens, the concrete near the bolts cracked with the bolts bending yield failure. The load-slip curves of the connectors had four distinctive stages corresponding to four different loading states of the tested bolts. The shear bearing capacity of the bolted connector was found to be mainly depended on the bolt diameter, the bolt tensile strength and the concrete strength. Finite element models verified by the experimental results were also developed, and used to conduct parametric analyses for investigating the effects of the bolt pretension, the bolt diameter, the bolt tensile strength and the compressive strength of concrete on the failure mode, the load-slip characteristics and the ultimate strength of the bolt connectors. Finally, based on the experiment results and FEA, design formulas for predicting the shear bearing capacity of bolt connections under different failure modes were proposed, which could be used in the design of high strength bolt connections in composite structures.