Load-carrying capacities and failure modes of scaffold-shoring systems, Part II: An analytical model and its closed-form solution

Critical loads and load-carrying capacities for steel scaffolds used as sho ring systems were compared using computational and experimental methods in Part I of this paper. In that paper, a simple 2-D model was established for use in evaluating the structural behavior of scaffold-shoring systems. Thi s 2-D model was derived using an incremental finite element analysis (FEA) of a typical complete scaffold-shoring system. Although the simplified mode l is only two-dimensional, it predicts the critical loads and failure modes of the complete system. The objective of this paper is to present a closed -form solution to the 2-D model. To simplify the analysis, a simpler model was first established to replace the 2-D model. Then, a closed-form solutio n for the critical loads and failure modes based on this simplified model w ere derived using a bifurcation (eigenvalue) approach to the elastic-buckli ng problem. In this closed-form equation, the critical loads are shown to b e function of the number of stories, material properties, and section prope rties of the scaffolds. The critical loads and failure modes obtained from the analytical (closed-form) solution were compared with the results from t he 2-D model. The comparisons show that the critical loads from the analyti cal solution (simplified model) closely match the results from the more com plex model, and that the predicted failure modes are nearly identical.