Robustness of column-supported modular steel buildings in column loss: Role of double-layer beams and point-restrained slabs

This paper examines the collapse performance of column-supported modular steel buildings (CSMSB) under various column loss scenarios. It recognized the differences in collapse mechanisms between the double-layer steel beams and point-restrained slabs of CSMSB and those of traditional steel frame structures. Detailed analyses focused on the anti-collapse contributions of beams and slabs, investigating the effects of column loss location, slab thickness , rebar ratio and beam height on collapse performance. Comparisons were conducted on the effectiveness and economy of improving the collapse resistance of CSMSB by changing different structural parameters, including changes in slab thickness, rebar ratio and beam dimensions. A proposed integrity enhancement strategy—incorporating vertical connections between the double-layer beams—was evaluated for its effectiveness in improving collapse resistance of the structure. Results indicate that the robustness of CSMSB is the greatest in scenarios involving general interior column loss (GICL), and smallest in corner column loss (CCL). The anti-collapse contributions of the slab are basically the same at initial stage for the four scenarios, while at the final collapse state, the slab contribution is the smallest in GICL (35 %) and the greatest in CCL (70 %). Axial restraints significantly influence the collapse resistance of CSMSB, particularly at large deformation . Compared with rebar ratio and slab thickness, increasing the beam height is the most effective and economic approach to enhance the collapse resistance of CSMSB. Furthermore, adding vertical connections between the double-layer beam can significantly enhance the collapse resistance of the CSMSB in different scenarios. However, resistance increase rate of the structure decreases with the increase of the connection number. • Collapse performance of CSMSB under various column loss scenarios is studied. • Contributions of beam and slab are discussed. • Effects of boundary condition, slab thickness, reinforcement ratio and beam height on collapse performance are studied. • Robustness enhancement strategy of CSMSB is proposed.