Behaviour and design of wire and arc additively manufactured steel T-stub connections

Wire and arc additive manufacturing (WAAM) has emerged as a promising and cost-effective technique for producing large-scale, complex steel structures in the construction industry. Given that large-scale structures often require component printing and assembling via bolts or welds, understanding the behaviour of WAAM steel connections is crucial for promoting WAAM applications. The T-stub bolted connection is considered one of the most commonly used and reliable methods for joining steel structural elements. However, due to the inherent geometry undulations and material behaviour, the structural behaviour and design methods of WAAM steel T-stub connections require further investigation. In this study, 12 WAAM steel T-stub bolted connection specimens with varying bolt arrangements and geometric dimensions were fabricated. These specimens were dimensionally measured with the 3D laser scanning technique and tested under monotonic tensile loading. Based on the tests, the existing design methods for conventionally manufactured steel T-stub connections were evaluated by comparing the predicted failure modes, initial stiffness, plastic and ultimate resistance against the test results. It is shown that while existing design methods could accurately predict the failure modes of WAAM T-stub connections, the plastic and ultimate resistance were underestimated. The initial stiffness of the WAAM specimens from existing methods was well predicted. Therefore, improved design methods to predict the plastic and ultimate resistance of WAAM steel T-stub connections were developed, and a reliability analysis was carried out based on test results and additional data from the literature. It was proven that the proposed design methods can provide accurate and consistent predictions for the resistance of WAAM T-stub connections.