Development of hollow ball joints for 3-dimensional space trusses-full scale tests and calibration for numerical analysis

The hollow ball joints, which consists of a hollow ball, high strength bolts, cones, washers and tube members, have been developed to construct space roof trusses. Six specimens comprising of a hollow ball, bolts and washers were tested under various combined loads. The ball diameter and thickness are 200mm and 27mm, respectively, and the bolt diameter is 36mm. The primary objective of study is to investigate the relationships between the ball deformation, the force required to pull the bolt out of the ball, and the ultimate strength of the bolts. Finite Element (FE) models were calibrated by comparison with the test results. Parametric FE analysis might be effective to determine the best joint dimensions in space trusses.