An experimental study into the structural behaviour of Directed Energy Deposition-arc or wire arc additively manufactured (DED-arc AM and WAAM, respectively) steel double-lap shear bolted connections is presented. The mechanical properties of the material, which had a nominal yield stress of 420 MPa, were first determined by means of tensile coupon tests. Sixty connection specimens of two different nominal thicknesses and two print layer orientations were then tested to failure. The geometry of the test specimens was determined by 3D laser scanning, while the deformation and strain fields were measured during testing using digital image correlation. The observed failure modes included shear-out, net section tension, bearing and end-splitting, while a new hybrid mode of shear-out and net section tension was identified for the first time. The test results were compared against the predictions of current design specifications, namely AISI S100 and AS/NZS 4600 for cold-formed steel and AIS
An experimental investigation into the structural performance of wire arc additively manufactured (WAAM) steel single-lap shear bolted connections is presented in this paper. The steel wire had a nominal yield stress of 420 MPa. Sixty specimens of different thicknesses, printing strategies and geometric features including end distances and plate widths were tested and analysed. The shear-out, net section tension fracture, localised tearing and curl-bearing failure modes were observed and discussed, while end-splitting was also evident. Digital image correlation (DIC) was used for detailed monitoring and visualisation of the surface strain fields that developed during testing, providing valuable insight into the developed failure mechanisms. The experimental results, which generally followed the anticipated trends, were used to assess the applicability of current design specifications developed for conventional steel bolted connections to WAAM steel bolted connections. It was found that
Abstract
The commentary to the North American cold-formed steel specification recommends physical testing to determine the performance of a bolted connection where the plies are not in contact with each other. This paper presents the laboratory test results of 120 such specimens with sheet thicknesses ranging from 0.55 to 3.0 mm, bolted with 10-, 12-, or 16-mm bolts. Finite-element analyses support the experimental finding that the bearing failure of an unconfined bolted connection is not associated with shear fracture but with crimpling of the critical ply. The bearing capacity varies with the square root of the bolt diameter and nonlinearly with the sheet thickness. Dimensionally consistent and continuous design equations are derived and verified against the results of the laboratory tests and finite-element analyses, the latter supplementing the former with configurations involving 8-mm bolts. The derived relationships between the bearing capacity and the sheet thickness and bolt
Abstract
This data paper presents the experimental investigation of unconfined cold-formed steel double-shear bolted connections where the applied load was stopped at different stages of loading (25% or 65% of the ultimate failure load under monotonic loading) followed by unloading, and finally reloading until failure. A total of 78 bolted connections of cold-formed steel subjected to loading-unloading and reloading conditions with sheet thicknesses ranging from 0.55 to 3.0 mm, bolted with 10, 12, or 16-mm bolts were investigated and compared to the identical specimens subjected to monotonic loading. The failure mode of the specimens tested under both loading conditions was bearing of the inner sheet. The test results show that ultimate capacities obtained from unloading and reloading tests were, on average, lower than those obtained from the monotonic tests. A similar trend was also observed for the displacement corresponding to the ultimate loads. However, the effects of sheet thi