Compressive Behavior of a Fully Prefabricated Liftable Connection for Modular Steel Construction

Modular steel construction (MSC) consists of the off-site prefabrication of a fully finished module and the on-site assembling of the module unit. The popularity of MSC is on the rise, attributable to its technical advantages of speed and quality of buildings with repetitive units. Inter-module connection is critical for the overall stability and load-bearing capacity of MSC. An innovative, fully prefabricated liftable connection (FPLC) using standard corner fittings and long stay bolts is proposed in this paper. This paper focuses on the axial compressive behavior and design of FPLC. Five full-scale specimens were tested under axial compression. Local buckling of the column and shear of the long stay bolts were observed during the test. It can be concluded from the test results that the load-bearing capacity may decrease as the number and diameter of the stay bolts increase. A three-dimensional nonlinear finite element model (FEM) was developed and validated against the test results by general purpose finite element software ABAQUS. Furthermore, a parametric study was conducted using the verified FEM to provide a better understanding of the axial compressive behavior of the FPLC. The results of the parametric study indicated that the corner fitting can be up to 15% lighter for columns with thicknesses of 6 mm and 8 mm without substantial reduction of the axial load-bearing capacity of the FPLC. Moreover, the location of the column can be adjusted to achieve a uniform Von Mises stress and equivalent plastic strain (PEEQ) distribution of the connection. The presented research work provides an engineering-practical inter-module connection on its axial compressive behavior, which will provide helpful references for further application of MSC.

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