Additive manufacturing (AM) is receiving increasing attention in the construction industry, owing to its potential to bring enhanced automation and sustainability. In order to achieve wider integration, this thesis is aimed at providing fundamental underpinning experimental data for wire arc additively manufactured (WAAM) steel bolted connections, including single- and double-lap shear bolted connections and T-stub connections. The applicability of current design specifications is also evaluated.
A series of material tensile coupon tests on the WAAM steel is presented. A total of 27 coupons, featuring two nominal thicknesses, two surface conditions (i.e. as-built and machined) and three print layer orientations, were tested. Advanced measuring techniques, namely 3D Laser scanning and Digital Image Correlation, were employed in the tests. Negative influences of surface undulations were evidenced while the differences between the different print layer orientation were found to be small.
A total of 120 WAAM single- and double-lap shear tests, 60 of each, with different thicknesses, print layer orientations and geometric configurations, were conducted using advanced measuring techniques. Conventional failure modes were observed and analysed, while several unique failure modes were also highlighted. The test results were compared against the design predictions of current design specifications and their accuracies were assessed.
Finally, tests on 80 T-stub bolted connections with different printing strategies, bolt arrangements and geometric configurations were carried out. A new method was introduced for the determination of the failure mode and key points on the load-deformation response of T-stub connections. The structural response of the WAAM T-stubs generally followed the anticipated trends, though the geometric irregularities and printing strategies were shown to have clear influences on the load-carrying capacity. Comparisons between the test results and the capacity predictions yielded by existing design equations were subsequently made; overall, reasonable agreement was achieved.
The work presented in this thesis has highlighted the feasibility and sound structural performance of connections produced through WAAM. Future research needs include the assessment of optimisation and structural reliability of WAAM connections.