A novel plug-in self-locking inter-module connection for modular steel buildings

Abstract

The inter-module connection of modular steel building components is key to ensuring the integrity and stability of modular steel buildings. To tackle the existing technical problems of the inter-module connection, especially those related to the complex on-site installation process, and ensure installation quality, this study presents a novel plug-in self-locking connection involving a lock cylinder consisting of two horizontal locking blocks, a locking plate, and an inner insert plate. A series of axial tensile tests were conducted on plug-in self-locking inter-module connections by changing the processing and the thickness ratio of different components of the locking cylinder (i.e. hP: hC: hI). In addition, mechanical tests were performed to study the axial tensile load capacity, axial tensile ductility factor, and failure modes of the locking cylinder of the plug-in self-locking inter-module connection with different configurations. The results show that the weld fracture of the locking plate and the inner insert plate can result in brittle damage to the connection, when the locking plate and the inner insert plate are manufactured as a whole, and the self-locking connection is rendered ineffective by shear fracture of the horizontal locking block. Among all the specimens, the ultimate tensile load capacity of the lock cylinder of Specimen R70NCB40 can reach around 293 kN with a tensile ductility factor of around 4, showing better mechanical properties. In addition, the thickness ratio of different components of a lock cylinder (i.e. hP: hC: hI) plays an important role in governing the mechanical capacity of the lock cylinder due to its relatively low tensile strength achieved through reducing the thickness of the inner insert plate (i.e., R70NCB40). This demonstrates a better mechanical performance of the cylinder through fully utilizing the plastic deformation capacity of different components of the locking cylinder. The recommended thickness ratio of different components of the lock cylinder (i.e. hP: hC: hI) is 1:1:0.68. Finally, based on the experimental and FEM results, an empirical theoretical model for the lock cylinder of a plug-in self-locking connection was proposed for the design of plug-in self-locking connections in engineering practice.