Collapse testing of steel-concrete composite floor systems under an exterior-column-removal scenario

To evaluate the influence of openings in floor slabs on the collapse performance of steel-concrete composite floor (SCCF) systems, 2 one-third scale 1 x 2 bay SCCF substructures were fabricated and tested under static load up to final collapse in an exterior-column-removal scenario. The experimental results indicated that arch-shaped and radial cracks emerged on the top and bottom surfaces of the floor slab, respectively, for the SCCF substructure without openings in the floor slabs. Meanwhile, local buckling of the steel girders at the beam ends successively occurred during the loading procedure. As for the SCCF system with openings in the floor slabs, the crack distri-bution appeared more irregular, and torsion of the spandrel beam became prominent because of the discontinu-ity of the floor slab. The ultimate collapse resistance and the corresponding displacement of the failed column for the substructure with openings in the floor slabs were about 0.85 and 0.55 times as large as those of the substruc-ture without openings. Owing to the existence of the openings, the tensile membrane action in the floor slab was weakened prominently, which further decreased the collapse resistance capacity of the SCCF system. After the removal of the exterior column, load was redistributed among the columns around the failed column and much more load was assigned to the adjacent exterior column. The flexural action and catenary action of the composite beams, as well as the tensile membrane action of the floor slabs worked together to resist collapse load at the large deformation stage. (c) 2021 Elsevier Ltd. All rights reserved.