Ultimate capacity and stability of topologically optimised shear plates in compliance with structural Eurocodes

Abstract

Topology optimisation (TO) is increasingly used to assist metallic parts manufacturing in automotive, aerospace, and biomedical sectors. A similar trend is observed in civil engineering structures, particularly in steel construction joints representing crucial steelwork components. Yet, the widespread adoption of TO to steel members in structural engineering has been hampered by difficulties complying with code requirements and challenges in utilising cutting-edge software in real, heterogeneous, and complex cases. To fill this research gap, a methodology is developed in the current study to implement the requirements of Eurocode 3 in the TO process. Nonlinear Finite Element Analyses (NLFEA) are performed on the web cover-plates of a well-known bolted splice connection between segments of a steel beam to validate the code-compliant methodology. Results show that it is possible to reduce up to 87.5% of the plate initial volume while keeping the connection original capacity. Also, it has been found that the initial volume can be reduced up 20% without affecting the original plate capacity, and up to 60% while ensuring that the ultimate plastic displacement is larger than that of the original plate. Based on extensive buckling analyses, critical loads exceed ultimate loads from 9.3 to 12.4 folds, thus ensuring excellent stability performance. The results of this study demonstrate that validation with NLFEA is a crucial step for achieving actual code-compliant optimised steel joints, and that the linear elastic TO could not satisfy the safety requirements. Moreover, encouraging findings regarding stability and ductility of (extremely) optimised parts suggest the adequacy of TO for designing steel connections. The volume of topologically optimised solutions significantly decreased, contributing to the decarbonisation targets for steel construction.