Progressive Collapse Dynamic Analysis of a Long-Span Space Grid Structure with Special Braces

The current research on the progressive collapse resistance of space grid structures mainly used the alternate path method, without considering the failure causes or mechanism of brace and the dynamic performance on residual structure, which cannot accurately evaluate the progressive collapse resistance of space grid structures. In this paper, a special brace is proposed for accurately distinguish asymmetric responses under compression and tensile loading. The material constitutive model of the special brace considering its buckling is implemented in FEM codes based on the explicit user materials subroutine (VUMAT). Then, the dynamic nonlinear analysis on a large-span space grid structure utilizing special braces was carried out to study the failure sequence of braces and the progressive collapse resistance of the structure. The analysis results show that when special brace is adopted, the occurrence of the initial failure of brace and the final collapse of the structure are earlier than the previous structure. The ultimate bearing capacity of the dynamic progressive instability of the whole structure caused by the buckling of local compression braces is significantly lower when compared with the alternate path method, which better reflects the collapse process of the actual structure and can be applied to the progressive collapse analysis of the space grid structure.