Static performance of double-ring joints for freeform single-layer grid shells subjected to a bending moment and shear force

This paper discussed a new type of bolted joint named a double-ring joint used in freeform single-layer grid shells. Prototype static tests and numerical simulations were undertaken to investigate the mechanical behavior of the bolted joint subjected to the bending moment and shear force. The main conclusions of this study are as follows. There are two primary failure modes of double-ring joints. One is the fracture of the bolt, and the other is the instability of the central ring. The failure mode depends only on the ratio of the ring thickness to the ring diameter when the height of the ring and the diameter of the bolt match. Ultimately, the simplified formulae for the load-bearing capacity of a double-ring joint in different failure modes were proposed as a reference for joint design.