Comparative study on collapse behavior of modular steel buildings: Experiment and analysis

With the increasing adoption of modular construction technology, understanding the modular steel buildings' collapse mechanisms has become crucial. This study presents comparative collapse tests on two modular steel substructures: specimen in corner column loss (S-CCL) and specimen in side column loss (S-SCL). The failure modes, load-bearing capacities, lateral displacements of modules, relative slips of double-layer beams, and deformation mechanisms of the components were compared. The findings reveal significant buckling at the ends of module beams far from the column loss area in both specimens, with minor buckling near the column loss area. No bolt hole fracture is observed in S-CCL, while S-SCL exhibits clear fractures. S-SCL demonstrates approximately double the load-bearing capacity of S-CCL during the elastic stage, and this increases further in the elastoplastic stage due to catenary action, ultimately reaching three times that of S-CCL. Significant lateral displacement occurs only in the double-span beam direction of S-SCL, towards the column loss area, while in other directions, displacement is minor and directed away. Digital image correlation (DIC) measurements indicate that relative slip in double-layer beams is significantly smaller in S-SCL compared to S-CCL. Strain gauge readings show that both module columns remain within the elastic range, but columns in S-SCL continue to deform in the plastic stage due to tensile forces in the connected beams, with beam ends away from the column loss area experiencing negative bending moments.