Structural behaviour of demountable tubular column-to-base plate joints with welded studs

Demountable joints play a key role in enabling structural reuse and sustainable construction. By reducing material waste and facilitating future adaptability, they contribute to more resource-efficient building lifecycles. This study presents a novel demountable column-to-base plate joint for tubular steel structures, designed to enable disassembly and structural reuse in alignment with circular economy principles. The proposed connection, composed of four angle cleats and welded studs, is evaluated through full-scale testing and validated finite element modelling. A validated numerical model was first developed using data from eight experimentally tested joints, achieving good agreement with measured rotational stiffness, with a mean absolute percentage error of 1.87 %. This model was then used to simulate an extended set of 23 configurations to investigate the influence of geometric parameters. Results reveal that wall thickness exerts a structural effect beyond its contribution to the moment of inertia, which may be attributed to local deformation mechanisms or elastic instabilities influencing joint stiffness in slender tubular profiles. When stiffness values are properly scaled, they collapse onto a single trend governed by the slenderness ratio, enabling the derivation of a generalized stiffness decay law for geometrically similar tubular joints. A refined component-based analytical model was also developed, capturing the observed trends and providing conservative estimates with acceptable accuracy. Compared to Eurocode formulations, which exhibit limited predictive capability for this joint typology, the proposed models offer a reliable and practical design tool for demountable tubular steel connections. • Novel demountable joint with angle cleats and welded studs is proposed. • Wall thickness affects stiffness beyond moment of inertia effects. • Normalized stiffness follows a unified trend with h/t slenderness ratio. • Analytical model predicts failure modes and matches experimental data. • All joints qualify as rigid according to Eurocode 3 stiffness criteria.