Experimental study of hemispheric rolling cable-strut joints for cable dome applications

Cable domes achieve structural stiffness and loading capacity through tension cables and compression struts. Friction from cable-strut joints contributes a major prestress loss during tensioning. This paper presents a novel hemispheric rolling cable-strut joint which provides smooth load transmission and high prestress efficiency. It comprises a hemispheric cover plate, a bottom plate, a roller, and top and bottom bearings. The bearings embedded in the roller reduce friction transmission from the tensioned cable; thus, prestress loss is minimized. A theoretical analysis of load transmission and prestress loss is conducted for the cable-strut joint, followed by an experimental study. The experiments test cable-strut joints with different types of bearings, using a fixed-roller joint as a reference, and are shown to validate the theoretical approach. A potential method to improve the prestress efficiency during tensioning is discussed. Prestress loss rates are compared for the test joints and an optimum bearing type is recommended in consideration of both friction coefficients and service time. The hemispheric rolling cable-strut joint accommodates complex cable and strut configurations with clear load path and minimal prestress loss. Our results show that it provides a high-performance solution that can be used to improve the structural stability and stiffness of next generation long-span spatial structures.