Metal additive manufacturing in structural engineering: Review, opportunities and outlook

Although still in its infancy, metal additive manufacturing (AM) has arrived at construction scale. In this paper, a review of recent developments in metal AM in structural engineering is presented, including the latest research advances, lessons learned from other sectors and applications in practice. Emphasis is placed on wire-arc additive manufacturing (WAAM) since this is deemed to be the most promising technique for the requirements of the construction sector. A description of the observed material response of both steel and stainless steel WAAM thin-walled elements, as well as the structural behaviour of crosssections, members, connections and systems, is provided. The challenges surrounding the inherent geometric variability of as-built WAAM material, as well as the implications of possible anisotropy, are discussed. Optimization and additive manufacturing go hand in hand, with the latter now enabling the former to be more readily realised in practice. Recent examples of optimized, additively manufactured structural components are presented. The economics and sustainability of WAAM are then discussed. Finally, with a view to the future, the opportunities and outlook for metal additive manufacturing, including the production and design of new structural elements, as well as its potential use in the strengthening and repair of structures, are presented.