Collapse resistance of steel modular buildings using a simplified inter-module joint model

This study evaluates the collapse resistance of steel modular buildings (SMBs) through a simplified inter-module joint model. Corner and edge column removal scenarios are analyzed for the single-storey, three-storey, and six-storey SMBs. The study investigates how joint configurations, including bolt arrangement and diameter, affect joint performance and overall collapse resistance of SMBs. A strengthening strategy, involving the connection of cover plates of the joint, is proposed, and its contribution to the structural resistance against collapse SMB is evaluated. The results show that decreasing the number and diameter of bolts reduces the tensile, shear and bending capacities of the joint by measurable margins. However, the reduce in overall structural anti-collapse capacity of the SMB remains relatively modest, ranging from 5 % to 13 %. By connecting the cover plates, the ultimate tensile capacity and ultimate shear capacity of the horizontal joint are enhanced by approximately 67 % and 35.4 %, respectively. Moreover, the structural maximum load capacity of the SMB is improved by 2.1 %–4.7 % in corner column loss and 5.1 %–12 % in edge column loss. By connecting the cover plates, the maximum structural load capacity of the SMB with the fewest bolts (two in the web and one in the flange) can be increased to nearly match that of the SMB with the most bolts (six in the web and two in the flange). The study stresses the vierendeel effect's key role in the multi-storey SMB's load-carrying capacity. Additionally, catenary action in module beam also plays a vital role in resisting collapse of the SMB under edge column loss. These findings provide valuable insights into the design and optimization of SMBs to enhance their robustness against progressive collapse.