Experimental and numerical analysis on the slope change joint of a quartet-steel-tube-column transmission tower

In this paper, a new type of multi-planar slope change joint (abbreviation SCJ) in a new type of long span transmission tower is presented. Difference between the new tower and regular ones lies in the tower leg. In the new tower, each leg is a built-up column constituted with four steel tubes. The SCJ is a complicated multi-planar connection in the tower. Three-dimensional loading of the joint was achieved in the experiment. Detailed configuration of the SCJ and the experimental system were introduced. Finite element models of the SCJ were established and validated against experimental results. Experimental and numerical analysis results, under different cases, indicated that the joint zone was within the elastic bearing capacity. Buckling failures appeared in the upper or lower tubes. Then parametric studies were carried out to study different factors that may have influence on the ultimate load. Axial load distribution among the four lower tubes in the joint was also analysed. Finally, some joint design recommendations were proposed.