Axial mechanical behavior of innovative inter-module connection for modular steel constructions

Modular steel construction (MSC) is a construction mode where volumetric modules are pre-fabricated in a factory and assembled on-site to form permanent buildings. Inter-module con-nections are critical to the integrity and robustness of modular steel constructions (MSCs). In this paper, the mechanical behavior of a typical corner inter-module connection under axial tensile and compressive loads was investigated. A tensile test of the inter-module connection was carried out to investigate their axial tensile behavior. The refined numerical model was established, calibrated against the test results and then used to simulate the axial tensile and compressive mechanical behaviors of the inter-module connection. The effects of key design parameters on the axial load-displacement responses of the connection, including the bolt gasket thickness, the bolt diameter and the preload were investigated. The inter-module connection was shown to exhibit excellent load-carrying capacity under axial compression and adequate performance under ten-sion. In terms of tensile resistances, the bolt gasket thickness and the bolt diameter were shown to be the critical parameters, while the section size of the modular columns dominated the compressive load-carrying capacity. Through geometrical parameters correlation analysis, a simplified piecewise polynomial axial load-displacement model with different stiffnesses in ten-sion and compression was employed for predicting the axial load-displacement relationship. The proposed model was shown to be capable of accurately capturing the axial resistance charac-teristics of the connection while maintaining simplicity, and is therefore recommended for use to represent the axial behavior of the inter-module connection in global frame modelling.