Mechanical performance investigations of a post-tensioned inter-module connection in steel buildings

Connections in modular steel structures are critical for maintaining structural integrity and facilitating ease of installation. Traditional methods, such as on-site welding, require adherence to complex technical specifications. In contrast, post-tensioned steel bolts offer a viable alternative by potentially reducing on-site labor by up to 50 %, providing substantial strength and simplifying assembly. To accurately assess the load-carrying capacity of post-tensioned steel connections, it is essential to analyze slip and shear load. This study investigates the behavior of a post-tensioned inter-module connection. Experimental and numerical analyses were conducted to evaluate the mechanical connection's performance under shear load. Laboratory tests on connection specimens assessed their strength and failure characteristics, while a finite element model was validated through these experiments. A satisfactory agreement between numerical simulations and experimental findings was found. A detailed numerical study examined the effect of bolt preload and wall friction coefficient on the load-carrying capacity of the connection. The higher bolt preload and higher wall friction coefficient enhanced the stiffness and shear strength of the connection. Additionally, a kinematic forcing method was used to evaluate the translational and rotational stiffnesses of a single post-tensioned modular connection. The elastic shear stiffness was also estimated from a simple analytical bolt model. Based on this solution, a connection optimization problem was formulated using selected design variables. The investigation findings offer valuable insights into the design of modular steel structures with structural connections.