ABSTRACT
The strength of hollow steel spheres used as nodes in tubular space trusses is investigated. The authors (1987, 1993) have previously reported experimental and analytical studies of the strength of balls without any stiffener. In the practice, as a ball is generally fabricated from two cold-formed hemispheres, the ball has often an interior diaphragm in its equatorial plane for the purpose of easily fabricating as well as reinforcement. This paper describes experimental and analytical studies on the reinforcement of the ball joints with an interior diaphragm. Uniaxial compressive tests of the ball joint with/without an interior diaphragm were carried out to investigate the effect of the reinforcement. Method of limit analysis is used to estimate the effect of the reinforcement by the interior diaphragm. Further, a practical formula is proposed for predicting the strength of the balls with the interior diaphragm.
