Automated steel construction manufacturing with robots is no longer just a dream of the future but a reality. The Institute for Steel Structures and Materials Mechanics of the Technical University (TU) of Darmstadt/Germany has two welding robots. These robots are being used to assess various application for Additive Manufacturing. For the construction of steel, Wire + Arc Additive Manufacturing (WAAM) is suitable, which is similar to Gas-Shielded Metal Arc Welding. The wire electrode serves as printing material. With this method we can produce components in layers and achieve deposition rates of 5 kg/h. The components studied in this research project are connection elements such as simply supported girder connections and head plates and reinforcing elements such as stiffeners and beam reinforcements. In this paper topology-optimized structures are presented, which can be printed with the WAAM directly on steel beams.