An experimental investigation of the behaviour of 3D demountable column-beam-slab composite substructures after column removal

This paper presents the experimental results of reduced scale (1:3) novel demountable steel-concrete composite structures consisting of columns, beams, and segmented slabs, after corner and edge column removal respectively, to investigate their progressive collapse behaviour. The slab segments were connected together by bent up reinforcement bars along the edges with secondary grouting between the segments. Their dynamic responses, load-displacement behavior, internal force redistribution, and failure mechanisms were systematically analyzed. The experimental results demonstrate that the novel demountable structural system exhibits excellent ductility and robustness performance. Even under very large deflections, the demountable structure using segmented slabs effectively transmitted both compressive and tensile forces, and the slabs behaved as monolithic reinforced slabs with in-situ cast concrete. Therefore, the conventional yield line theory for two-way spanning in-situ cast reinforced concrete slabs can be used for the demountable slabs of this research. • The demountable composite substructures demonstrated excellent robustness and reusability after column removal. • The segmented slabs with U-bar joints behaved monolithically and effectively transferred internal forces. • The yield line theory for in-situ slabs is applicable to the proposed demountable slab system. • Full deconstruction and reconstruction of the substructure had minimal impact on structural performance.