The Technical University of Braunschweig, Braunschweig, Germany, has reported that Linus Schmitz, a Civil Engineering graduate, received the German Steel Construction Award for his work to investigate the use of localised Additive Manufacturing to reinforce steel beams that are exposed to stresses.

In the research project at the Institute of Structural Design (ITE) at TU Braunschweig, Schmitz used Directed Energy Deposition (DED) AM to apply metal to the areas of steel profiles where the stresses are greatest, allowing for slimmer profiles, saving resources and reducing CO2 emissions in steel construction.

“This makes it possible to produce complex, free-form elements,” explained Schmitz. Additively manufactured components can be much better adapted to local loads, unlike mass-produced components such as rolled profiles, which can be efficiently manufactured industrially but have a standardised geometry and are, therefore, only used in high-stress areas.

The combination of serial production of rolled profiles and local reinforcement using DED thus combines the advantages of both manufacturing techniques. The content of the thesis originates from the research programme of project A07 of the Collaborative Research Centre TRR 277 Additive Manufacturing in Construction (AMC) of TU Braunschweig and TU Munich and was conceived by Professor Harald Kloft and Christoph Müller.

Schmitz produced five demonstrators at the ITE using the robotic DED Additive Manufacturing machine. He first carried out a series of tests to achieve a stable manufacturing process with the robot system and welding parameters, and to produce the thinnest possible reinforcement structures.

In his work, Schmitz systematically investigates the individual reinforcement of rolled profiles for different types of stress: instead of dimensioning a profile for the maximum stress in future steel construction planning, a profile with smaller dimensions can be selected. The area of maximum stress can then be locally reinforced with additional material using the WAAM process. This could potentially make an important contribution to circular construction in building practice and will be investigated using mobile robots in the second funding period of TRR 277 AMC, which is currently underway.

“This possibility of ‘personifying’ standardised profile rows with material reinforcements in layers according to the main stress lines of the moment curves offers new possibilities for detail design, especially for the designer or constructor interested in design quality, but also in material efficiency,” said the jury of the German Steel Construction Award. “In principle, a reduced use of materials goes hand in hand with the gracefulness of the filigree structure and the legibility of the flow of forces in the joints.

“One is reminded of the congenial collaboration between engineer and architect, for example in the formation of the struts of the steel girders for the canopies of the Palazzo del Lavoro, Turin, 1961, by Pier Luigi Nervi and Gio Ponte. […] In the age of resource-conscious construction, the imperative of material economy is also a highly welcome strategy of sustainability, in which ecology, economy, engineering and design complement each other in a happy way.”

“The fact that I was able to make a serious contribution to research with my work here naturally makes me very happy,” shared Schmitz. The results of the work have been published in a journal paper. Together with Neira Babovic from ITE, Linus Schmitz presented them at Eurosteel 2023 in Amsterdam.

“I want to investigate the interface between Civil Engineering and Architecture and close the gap between design, materials and manufacturing processes,” he added.

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