Experimental study on collapse behaviour of truss string structures under cable rupture

Cables are key components of truss string structures, and their sudden rupture may cause severe damage and progressive collapse of the structures. In this paper, cables were selected as the initial failure component, and the failure effect of a planar truss string structure with 6-m span was investigated through both experiments and numerical simulations. The deformation, internal force redistribution and oscillatory response of the remaining structure were obtained, and the progressive collapse failure mechanism was revealed. The results showed that, after the cable rupture, the stress state of the upper truss changed from an arch to a simply-supported beam, the lower chords of the middle span first exhibited plastic strain, then the mid-span upper chords and web members buckled successively, the structure collapsed. However, owing to the friction in the test, the structure demonstrated a slower collapse rate in the test than in numerical simulation. It was found that when the elastic support stiffness of the finite element model was 775 kN/m, the simulation results were more consistent with the experimental data, which further illustrated the correctness of the numerical simulation. In addition, the duration of the progressive collapse process of structures is very short, it is necessary to research anti-collapse measures.