Flexural Behavior of Steel–Concrete Composite Beams Utilizing Innovative Long-Nut Shear Connectors: A Numerical and Experimental Study

Abstract

This paper investigated flexural behavior of composite beams with innovative bolted shear connectors. The novel bolted shear connector consisted of a long tube nut and its compatible bolt. The nut was cast in concrete, and through predrilled holes on the flange of the steel beam, the bolts were connected to the nut to achieve interaction between the steel beam and concrete slab. Using this bolted connection, the stress concentration in the tangible medium around the nut was reduced. The composite beam with the novel bolted connectors was built and tested in the laboratory. The four-point experiments were carried out to investigate the stiffness, strength, and ductility of composite beams with novel bolted connectors, and the experimental results were compared with that of the composite beam with conventional connectors. The interaction at the interface of the composite beams in the elastic stage was discussed according to the strain distribution of the cross sections. The finite-element (FE) model of the composite beam was established using the commercial software Abaqus and validated using experimental results. A series of parameter analyses were carried out using the validated numerical model, including the nut diameter, bolt hole clearance, bolt pretension, concrete strength, and connector spacing. The results show that composite beams with bolted connectors have better performance than those with conventional connectors.