Flexural performance of T-shaped aluminum alloy beam-to-column joints with stainless steel bolts

This study proposes two types of aluminum alloy beam-to-column joints using stainless steel bolts as fasteners: joints with bolted T-shaped stainless steel connectors and joints with stiffened T-shaped stainless steel connectors. Five groups of static experiments were conducted. The joint failure modes, in-plane flexural stiffness, and strain development characteristics were analyzed to investigate how joint type, bolt diameter, and bolt arrangement affect static mechanical performance of the joints. The results indicate that the ultimate failure mode for joints without welded stiffeners is bolt bending-shear failure, while for joints with welded stiffeners, it is bolt pull-out failure. It was found that evenly spaced bolts enhance both the initial rotational stiffness and the ductility. Welding stiffeners to the T-stub caused negligible change in initial stiffness, but substantially improved the strength and ductility. Based on the experimentally validated finite element model, the effects of bolt size, bolt arrangement, web length, flange thickness, and stiffener thickness of the T-stub connector were investigated. Parametric analysis indicates that increasing bolt size and adding stiffeners significantly improve the stiffness and load-carrying capacity, while the effects of bolt arrangement, web length, and flange thickness on the ultimate capacity are limited. Finally, based on the component method, a theoretical formula for calculating the initial rotational stiffness of the aluminum alloy beam-to-column joints was proposed. Comparison with experimental results shows that the predicted values agree well with the test data, with an average error within 15%.