Working mechanism evaluations of full-scale joints with bolted-cover plate connection for modular steel buildings.

• Strengthening methods are designed to protect the beam–column welds within the module under seismic. • Four full-scale modular structural joint hysteresis tests are investigated. • The working mechanism of module-to-module connections is explored. • Comparison with different simplified modeling methods for modular structural joints is conducted. • The lateral stiffness of modular frames is provided based on simplified modeling and the D-value method. The force-reliability of the modular structural joints is crucial for ensuring the structural integrity of modular steel buildings. However, the welds connecting the beam and column within the module are susceptible to tear during seismic events. This mode of failure greatly undermines the ability of these joints to withstand seismic forces. Four full-scale modular structural joints with bolted-cover plate connection were designed and conducted for seismic performance testing, emphasizing the significance of methods such as reinforcing diagonal braces and strengthening flanges on the protective effect of beam–column welds in the module. The simplified modular structural joint and frame finite element model were proposed based on experimental data, refined finite element modeling, and theoretical analysis. The findings suggest that the seismic behavior of the modular structural joint remains unaffected by variations in axial compression ratio within the designed range of parameters. The beam–column weld of the module in the reinforced joint exhibits almost no weld tearing, and both strengthening methods demonstrate exceptional capacity for energy dissipation. The proposed simplified modeling method facilitates the efficient determination of the modular structural joint bearing capacity and the lateral stiffness of the modular frame. The research findings presented in this paper can serve as a valuable reference point for the engineering design of modular steel structures. [ABSTRACT FROM AUTHOR]