Study on the Ultimate Bearing Capacity Performance of Composite Stiffened Tubular Joints

TY-type intersecting joints are widely used in ultra-high voltage long-span transmission towers. To improve the ultimate bearing capacity of TY-type intersecting joints, this paper proposes a composite externally stiffened intersecting joint based on the TY-type joint, which involves setting vertical gusset plates and vertical stiffeners on the outer surface of the TY-type joint. In this paper, 3 different TY-type intersecting joints are designed, and experimental studies are carried out to explore the failure modes, load–displacement relationships, and plastic development laws of these different TY-type intersecting joints. The results show that stiffening measures can effectively enhance the ultimate bearing capacity and initial stiffness of the joints. Based on the experimental results, the correctness of the numerical simulation is verified. Taking the composite externally stiffened intersecting joint as the base model, 256 stiffened joint models are established, and numerical simulation is used to investigate the influence of different geometric parameters on the ultimate bearing capacity of the joints. The results indicate that: The use of gusset plates and stiffeners can significantly improve the ultimate bearing capacity and overall stiffness of the unstiffened joints; The failure mechanism of the composite stiffened joints is consistent with that of the unstiffened joints, both characterized by buckling in the core of the main pipe; The ultimate bearing capacity of the composite stiffened joints is positively correlated with the diameter ratio of the branch pipe to the main pipe, the thickness ratio of the external stiffening plate, the thickness ratio of the external stiffener, and the height ratio, while it is negatively correlated with the diameter–thickness ratio of the main pipe. The research results on the new-type intersecting joints in this paper can provide a design reference for their practical engineering applications in transmission towers.