There are mainly three types of rod connections in the space frame structure: welded ball joints, bolted ball joints and plate joints. ①The hollow ball joint has simple structure, low cost and large internal force of the rod. In small and medium-span grids, and even in the construction of large-span grids, the application is gradually increasing. Plant space frame often use this type of node. https://www.cnxzlf.com/category/accessories/bolt-ball/