Study on the Progressive Collapse of Large Span Truss-beam Structures Induced by Initial Member Break

Experimental study and numerical analysis are performed on the robustness of large span truss-beam structures. Apparatus with features of noninterference, expeditiousness and easy-handling has been invented for inducing initial member failure. Non-contact digital image technique and high frequency device are adopted to acquire the large displacement and strain in the dynamic process. The post-initial failure mechanisms, including pin rotation, shear sliding and long-member buckling, are revealed and found depending closely on the initial failure member location, and affecting subsequent structural behavior. The concept on sensitive member and key member is summarized, and a static analysis based method to identify these two types of members is proposed. A case study on a typical truss-beam-column system exhibits the simplicity and rationality of the method proposed.