Parameter Analysis of Progressive Collapse Simulation of Long-Span Spatial Grid Structures

To accurately simulate the collapse process of long-span spatial grid structures, certain key parameters should be treated carefully. In the present study, the effects of the strain rate and the damage and fracture parameters were analyzed. A numerical simulation shows the following information: (1) First, the Cowper-Symonds model is utilized to simulate the rate-dependent material properties, illustrating that the strain rate effect can be overlooked for a progressive collapse simulation. (2) Then, the constant failure strain method is used for a damage and fracture simulation. The first fracture of the members is postponed, and the final failure patterns are therefore quite different with an increase in the initial damage-equivalent plastic strain. (3) And, the progressive collapse pattern is unaffected while the fracture is delayed or prevented with a greater equivalent plastic strain of the final failure. These results can provide a reference for determining the damage and fracture parameters. (4) Finally, the equivalent plastic strain of the initial damage is relevant to the stress triaxiality. After considering the stress triaxiality, there is a significant difference compared with the constant failure strain model. The stress triaxiality must therefore be considered.