Progressive Collapse Behavior of Large-span Truss String Structures Subjected to Cable Failure

Cables play an important role in truss string structures, and their sudden failure can lead to massive damage and even collapse of the structures. This paper studies the dynamic response of a 72 m span truss string structure, the progressive collapse numerical simulation of the structure is carried out under different load conditions, the displacement and force responses of the structure after cable failure are investigated, the dynamic amplification factor is calculated, and the collapse mechanism is revealed. The effect of individual factor changes on the structural response is analyzed and compared. Results showed that after cable failure, the stress state of the upper truss changed from an arch to a simply supported beam, when reaching collapse load, the structure collapsed within 5s instead of reaching new equilibrium positions. Moreover, the structure with stiffer elastic support exhibited higher resistance to collapse. The critical member of the truss, which first buckled under compression, shifted from the mid-span to the lower chord at the end, leading to rapid structural collapse. Increasing the cable’s cross-sectional area can hardly reduce the structure’s dynamic response. However, when the instantaneous failure time of the cable exceeded 0.1s, a significant alleviation of the structure’s dynamic response was observed.