Experimental and numerical investigation into ultimate capacity of longitudinal plate-to-circular hollow section K- and DK-joints in transmission towers

摘要

Longitudinal plate-to-circular hollow section DK-joints are generally used in transmission towers. In this study, the ultimate bearing capacities of planar K- and multiplanar DK-joints were investigated. Full-scale three-dimensional experiments involving DK-joints were performed, and parametric studies were conducted to obtain the ultimate capacities of K- and DK-joints. In the simulation study of K- and DK-joints, branch axial forces were resolved into a bending moment (M-w) and a vertical component force (P-v). Ultimate strength equations for M-W and PP are proposed and compared with current guidelines. DK-joints have two branch plates, whereas K-joints have only one. Hence, the ultimate capacities of these two joints were compared for a single branch plate. Analysis results showed that in transmission towers, the ultimate capacity of the equivalent bending moment for DK-joints is about 0.89-1.0 times that of the equivalent bending moment for K-joints, and that the ultimate capacity of the vertical component force for DK-joints is about 0.605 times that of the vertical component force for K-joints. Interaction equations for M-W and P-v are proposed for both joints. Predictions of the proposed equations are in agreement with the existing test results.