Bolted end-plate connections are often designed using the equivalent T-stub model under the ultimate strength limit state. However, for structures subjected to service loads—and particularly to fatigue loads—there has been a lack of suitable computational models to realistically capture bolt stress.

As part of a master’s thesis in the Steel Structures Department, a numerical FE model of a T-stub was developed that accounts for the preload of high-strength bolts, contact conditions, support forces, and geometric imperfections. Following successful validation using experimental results from the previously studied L-stubs, a comprehensive parameter study was conducted. This study revealed, in particular, the significant influence of geometric imperfections on bolt tensile force and bolt bending moment. Based on the numerical results, an empirical calculation model was derived that reliably captures the nonlinear relationship between external load and bolt stress.