Bending, shear, and tensile properties of internal connection in modular steel construction

As modular steel construction (MSC) is assembled with modular units, the effective connections between modules are key elements. Previous forms of internal connections in MSC require operation spaces for connection, and the research model of internal connection includes the module-to-module connections and beam-to-column connections, which makes the connections inconvenient to assemble and makes it impossible to obtain the true properties of the module-to-module connection. This study introduces two forms of internal connections designed for easy assembly in MSC: the bidirectional bolted connection (BBC) and the threedirection bolted connection (TBC). The research model featuring only internal module-to-module connections was used to analyze and compare the bending, shear, and tensile properties of these two connections. The results demonstrate that, in bending states, the TBC offers a more robust semi-rigid and full-strength connection than the BBC, while also outperforming it in terms of shear and tensile properties. To further refine the design parameters of TBC, a parametric analysis was conducted to evaluate its behavior in bending, shear, and tensile states. The bolt preload has an effect on the properties in all states, the pin diameter has an effect on the properties in the shear state, and the axial load ratio of the modular column in the bending state is not recommended to be greater than 0.15. Subsequently, calculation methods of the bending, shear, and tensile mechanical property parameters of TBC were developed based on the component method, offering valuable insights for the design and application of internal module-to-module connections in MSC.