Experimental and Analytical Study on Failure Modes of Structural Steel Scaffolds

Steel scaffolds are temporary structures usually used in construction to support various types of loads. Four 3D full-scale scaffold-frames with different geometric and connection properties were constructed and tested statically in Cairo University Structures Lab. The aim was to obtain the strength as well as the failure modes of these four common scaffolds available in the local construction market. Nonlinear Finite-Element-Analysis was conducted for the four frames in order to verify strength and failure modes of the scaffolds and to compare with experimental results. Parametric studies were carried out based on the Finite-Element-Analysis results, in order to investigate the influence of various geometric arrangements and properties on the behavior of similar scaffolds. Based on both experimental and analytical results, it was concluded that the most common failure mode for 3-D free-standing-scaffolds was the sway-frame-buckling about its weak plane. For quick-form scaffolds (e.g. Cuplock and wedge types), the failure load-factor was found to be very sensitive to the rotational stiffness of the “standard-to-ledger” connection. For X-braced-scaffolds, the failure load-factor was shown to depend on the tie height. Other conclusions and recommendations are presented to the construction industry. 

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