Anti-progressive collapse mechanism of long-span single-layer spatial grid structures

The anti-progressive collapse mechanism of long-span single-layer spatial grid structures was comprehensively examined. A model of substructures was constructed from the basic units of single-layer spatial grid structures. Eight full-scale test specimens were designed on the basis of the model of substructures, and a static testing apparatus for spatial loading was developed. Experimental results, including the load-displacement responses, sequences and modes of failure, and strain measurements, were analyzed, and the anti-collapse mechanism was examined. A numerical simulation was conducted for two types of single members derived from test specimens. The experimental results and numerical analysis showed the following. (1) For specimens with a 0° inclination of the member, the bearing capacity was mainly provided by the beam mechanism when the displacement was less than 50 mm. After the displacement exceeded 150 mm, the catenary mechanism began to resist more of the vertical load. (2) For specimens with a 30° inclination of the member, the compression mechanism was developed and the displacement was small. (3) The beam and catenary mechanisms translated to the compression mechanism when the inclination of a member was greater than 5°.