The flexural mechanical response of a novel plug-in self-locking inter-module connection for modular steel buildings

The bending-deformation resistance of a proposed plug-in self-locking inter-module connection was investigated. Firstly, bending tests were conducted on three foot-size plug-in self-locking inter-module connections. Secondly, the corresponding finite element model (FEM) was established with ABAQUS finite element software, and then verified through tests. A parametric analysis of the connection was also performed to estimate the influences of the construction clearance on the mechanism of synergistic strengthening between an inner insert and a lock cylinder. Finally, design recommendations are given for this self-locking connection. The results show that: firstly, the damage modes of the unreinforced insert specimens all involved shearing fracture at the lower part of the insert, and the slope-reinforced insert specimens underwent necking at the interface of a locking core plate and an insert plate with a ductility coefficient of 1.134. In addition, the load direction had no effect on the flexural capacity of the connection, while the initial flexural stiffness of the slope-reinforced interpolated plate connection was improved by 3.6% compared to the connection with unreinforced interpolated plate. And the flexural ultimate loads of all three specimens reached 5% of the design flexural load of the modular column. Secondly, the complete M-theta curve of the slope-reinforced inset plate connection is divided into the elastic phase, elasto-plastic phase and inner insert-reinforced phase. Thirdly, the initial flexural stiffness of the connection with g = 0 mm is 1.8 times higher than the connection with g double dagger 0 mm. When g = 2 mm, the connection had the extreme values of the reserve load capacity (27%) and the ductile deformation capacity (mu II = 1.36). In addition, at the stiffness enhancement point of the M-theta curve, there is a linear relationship between the rotation angle and construction clearance. Finally, the results found that a negative correlation between the flexural ultimate load and the construction clearance.