Generalized method for identifying yield-line patterns in T-stubs using discontinuity layout optimization

Abstract

The so-called “plate in bending” is an essential component in typical steel connections. The underlying concept is the T-stub model. Typically, the resistance of a T-stub is obtained with the upper bound theorem, which means that a kinematic failure mechanism must be assumed. The most relevant failure patterns and the corresponding resistances of typical T-stub configurations can be found in the standards, like the EN1993–1-8. A general method for identifying the correct yield-line pattern and for calculating the resistance for any T-stub configuration is still not available. To overcome this unsatisfactory situation, such a generalized method has been worked out in the presented research. This was made by extending the “Discontinuity Layout Optimization” (DLO) procedure by including the internal work dissipated by the bolts. The approach was validated on a broad range of relevant applications, such as typical unstiffened and stiffened T-stubs, as well as more complex configurations, which are not ruled by the standard. The obtained results were compared with results from experiments and analytical solutions from the literature. Overall, the modified DLO approach is able to reproduce the failure patterns and the ultimate loads of the investigated bolt configuration correctly.