Development of Novel Sigma-shaped Self-locking Inter-modular Joints for Robust Modular Steel Buildings

Abstract

Modular Steel Buildings (MSBs) are a new structure consisting of fully assembled volumetric units. The inter-modular connections are essential components contributing to MSB’s onsite assembly and structural safety. It is necessary to have a precise and valuable intermodular joining system that allows for efficient load transfer, safe handling, and the most efficient use of the modular components’ strength. The majority of inter-module connections are currently manual vertical column-to-column welded, bolted, or prestressed, which has a lot of shortcomings, including poor quality, inefficient construction, lack of space, full connectivity, and incompatibilities with interior design. Moreover, due to a discontinuous horizontal diaphragm and vertical walls, the lack of horizontal and vertical beam-to-beam connections between modular units reduces in-plane and out-of-plane stiffness and uniform lateral force transmission. To overcome the concerns mentioned above, this study first presents a unique self-locking automatic vertical column-to-column inter-modular connection that uses connection boxes with spring-loaded tenons and mortises with tongues and grooves to achieve vertical connectivity. Then, to guarantee horizontal diaphragm continuity, a horizontal beam-to-beam interlocking connection with a continuous group of interlocking clips with sigma-shaped tongues and grooves is proposed, welded on modular floor beams. Then, a vertical beam-to-beam interlocking connection with a group of interlocking clips is developed, welded on beams offsite to achieve vertical diaphragm continuity. The proposed vertical and horizontal connections satisfy simple splicing, non-welding, easy installation, complete and robust connectivity, and reliable connection characteristics. Furthermore, finite element analysis revealed that developed connections enhance in-plane rigidity and improve MSB vertical and horizontal connectivity, maximizing modular building assembly benefits.