Structural behavior of a wire arc additively manufactured steel eye bar for the repair of a historic high-tech facade

The practice of early demolition and replacement of building facades in the architecture, engineering, and construction (AEC) industry, particularly metal facades, raises significant sustainability and preservation concerns ranging from the loss of valuable materials, increased carbon emissions, and the erosion of architectural heritage. This research focuses on innovative metal facade structures from the second half of the 20th century that are particularly vulnerable due to their novel construction techniques and materials. It examines a possible repair scenario using the facade construction of the CLA research facility at ETH Zurich as a case study, illustrating the challenges of repairing a complex metal facade that is not protected by conservation regulations but is treated as a listed building. The research explores the potential of digital fabrication, specifically Wire-and-Arc Additive Manufacturing (WAAM), as a viable solution for producing the bespoke replacement parts needed to repair such facade structures. The paper illustrates the production and testing of the printed specimens under compressive and tensile loading, focusing on force-displacement curves, strain distributions, and failure modes. A total of eight specimens are tested, four in tension and four in compression. The experimental results show a ductile behavior of the WAAM parts, and a significantly higher load-bearing capacity than is necessary for transferring the forces occurring in the considered facade. The experimental results are then compared with those obtained from calculations according to existing standards. A porosity analysis is performed on two test specimens, subjected to compressive and tensile loading. The study demonstrates that WAAM, with its capability for mass customization and rapid material deposition, is a viable method for producing high-quality, on-demand components that meet the stringent requirements of facade preservation.