Experiments and analysis of the post-buckling behaviors of aluminum alloy double layer space grids applying ball joints

This study discusses on the experimental and analytical results of the glob al buckling tests, carried out on aluminum alloy double layer space grids c omposed of tubular members, ball joints and connecting bolts at the member ends, with the purpose of demonstrating the effectiveness of a simplified a nalysis method using an equivalent slenderness ratio for the members. Becau se very few experiments have been carried out on this type of aluminum spac e grids, the buckling behavior is investigated experimentally over the post buckling regions using several space grid specimen with various values for the member slenderness ratio. The observed behavior duping the experiments is compared with the analytically obtained results. The comparison is made based on two different schemes; one on the plastic hinge method considerin g a bending moment-axial force interaction for members and the other on a m ethod using an equivalent slenderness ratio. It is confirmed that the equiv alent slenderness method can be effectively applied, even in the post buckl ing regions, once the effects of the rotational rigidity at the ball joints are appropriately evaluated, because the rigidity controls the buckling be havior. The effectiveness of the equivalent slenderness method will be wide ly utilized for estimation of the ultimate strength, even in post buckling regions for large span aluminum space grids composed of an extreme large nu mber of nodes and members.