Experimental and analytical studies on the stability of structural steel tube and coupler scaffolds without X-bracing

Systematic experimental and analytical studies are presented in this paper on the stability of structural steel tubes and coupler scaffolds without X-bracing (hereinafter referred to as STCS). Twelve full-scale STCS specimens with various geometric properties were constructed and tested statically in the lab, in order to obtain the strength as well as the failure modes of typical STCS’s. Advanced nonlinear finite element analysis was conducted on the specimen models using the ANSYS program, in order to obtain the strength and failure modes of the STCS’s and to compare with experimental results. Parametric studies were carried out based on the FEA results, in order to investigate the influence of various geometric properties on the stability behavior of STCS’s.Based on both the experimental and the analytical results, it can be concluded that the typical failure mode of STCS’s is global buckling about the weak axis. The strength was found to be sensitive to the rotational stiffness of the coupler, the storey height, and the U-head height, but insensitive to the post spacing and the sweeping staff height. Furthermore, a simplified model and formula were established for the strength of STCS’s under uniform load and presented in the paper, which were verified by the experimental and analytical results and which turned out to be accurate enough in predicting the strength. In the end, recommendations are proposed for the design of STCS’s based on the research results, which provides a very useful reference for the industry as well as academia for design and future research.