Research on Mechanical Properties of Inner Sleeve Connected Joint Between Modules of Fabricated Modular Steel Frame

The finite element numerical simulation of the inner sleeve connected joint between the modules of the fabricated modular steel frame was carried out. The influences of the gap between the inner sleeve and the column wall, the thickness and the length of the inner sleeve on the bearing capacity of the joint were studied. The forming mechanism and theoretical calculation formula of the contact force between the column wall and the inner sleeve were analyzed. The formula for calculating the contact force between the inner sleeve and the column wall was derived and compared with the finite element numerical results. The research showed that the reserved gap between the inner sleeve and the column wall had a significant impact on the bearing capacity, stress distribution and contact force of the joint. When there was no gap between the inner sleeve and the column wall, the stress distribution of the column wall in the joint area was more uniform. With the increase of the reserved installation gap, the contact stress between the inner sleeve and the column wall was uneven, and the bearing capacity of the joint decreased. It is recommended that the reserved gap between the inner sleeve and the column wall should not exceed 4 mm; When the inner sleeve thickness was greater than the column wall thickness, the joint stress distribution was more uniform, it is recommended that the inner sleeve thickness should be greater than the column wall thickness of 1 to 2 mm. Appropriately increasing the length of the inner sleeve is beneficial to the uniform distribution of joint stress and improve joint bearing capacity. It is suggested that the inner sleeve should extend the upper beam flange and the lower beam flange by 30 to 50 mm respectively. The error between the theoretical calculation formula and the numerical calculation result of the contact force between the column wall and the inner sleeve was about 10%, because the influence of axial bending deformation of the column was ignored in formula.