Performance of built-up T-stubs for Double T moment connections

• Strength of specimens was larger than strength predicted by design recommendations.
• Numerical model reproduced strength, stiffness, and deformation of specimens.
• Cyclic response of models shows no damage to weld zone after several cycles.
• Monotonic force–deformation curve can be used to predict cyclic response.

The behavior of built-up T-stubs subjected to tensile loading through the stem is studied through numerical and experimental models. The aim of the research is the determination of limit states that control the behavior of built-up T-stubs and the evaluation of the applicability of current design recommendations for double split tee moment connections when the split tees are replaced by built-up T-stubs. A series of one-half scale T-stubs specimens were tested under monotonically increasing tensile loads. The experimental results show significant overstrength with respect to that predicted by current design recommendations and differences between the expected and actual failure modes. No weld failures were observed. Detailed 3D finite element models of the specimens tested were created and subjected to monotonic tensile loads. The models reproduced the load–deformation response and failure modes of the test specimens and enabled an improved understanding of the location and level of damage of the built-up T. They can be used to study the cyclic response of these components.