Investigation of Shear Behavior in High-Strength Bolt Connectors for Steel-Concrete Composite Beams

High-strength bolt connectors, known for their robust strength and ease of disassembly, are suitable not only for the construction of new steel-concrete composite beams but also for reinforcing existing composite or steel beams. Static push-out tests were performed on nine specimens to examine their shear behavior. The primary failure mode was observed at the steel-concrete interface, characterized by the tensile-shear failure of the bolt and localized crushing of the concrete beneath the bolt. The preload had no significant influence on the ultimate bearing capacity and ultimate slip displacement, while it had a substantial impact on the initial slip load. The failure process was divided into static friction at the interface, sliding at the interface, elastic deformation of the bolt, and plastic deformation of the bolt. The parametric analysis using the finite element method was performed to assess the impact of concrete strength, reserved hole diameter, interface friction coefficient, and bolt diameter and strength. It revealed that the ultimate bearing capacity is composed of interfacial friction and bolt shear capacity, which are not independent of each other. To decouple these components, a novel calculation method for determining the ultimate bearing capacity of high-strength bolt connectors was developed and validated using existing test data.