EXPERIMENT RESEARCH ON LARGE-SCALE DIAGRID TUBE UNDER CIRCULAR MULTIPOINT LOADING

Diagrid tube has significant advantages in vertical and lateral horizontal load-bearing capacities. It is characterized by large lateral stiffness and high overall stability, and has been currently widely used in practical engineering. Several hyperboloid diagrid tubes are adopted as bottom support structures in the China Comic and Animation Museum in Hangzhou, of which the Y2 grid tube structure has both the largest scale and vertical loads on its top. Owing to a lack of both circumferential members (except the top ring beam) and radial lateral braces along the height direction, the Y2 tube structure would be prone to out-of-plane multi-column instability fail when subjected to vertical loads. Current design method in predicting the vertical bearing capacity of the grid tube are not available, thus experimental studies are recommended. This paper designed a new scheme of vertical loading experiments on grid tubes to realize the conversion from a single point vertical load applied at the top point of a load distribution structure to multi-point vertical loads applied on the top of the Y2 diagrid tube structure. This scheme not only saved the experimental space and cost, but also accurately realized the real load distribution ratio on the top of the Y2 tube structure. The experiment results revealed that the failure mode of the Y2 diagrid tube structure was regional multi-column instability at both sides of the opening 1. The ultimate bearing capacity of the Y2 diagrid tube structure specimen was found to be 3.37 times its design load, indicating that the Y2 diagrid tube structure had sufficient bearing capacity within a rational safety margin.