Stability Analysis of Basic Load-Bearing Units in Independent Scaffolding Systems

Scaffolds, as temporary structural support systems in civil engineering, play an essential role during construction. Independent steel scaffold systems, typically composed of assembled steel tubes, can be erected and function as standalone supports without mutual interference. This feature offers notable advantages over conventional scaffolding, including easier dismantling and higher reusability efficiency. However, the absence of specific design and construction codes for this type of scaffolding has hindered its broader application, underscoring the need for further research into its structural reliability. This study investigates the stability of basic load-bearing units in independent scaffolding through vertical loading tests on three specimens with varying heights and end conditions. The failure modes of the specimens are systematically compared, and the load-transfer mechanism and mechanical behavior of the scaffold units are analyzed. Experimental results, validated against ABAQUS finite element simulations, reveal that the critical region under axial compression lies at the junction between the inner and outer tubes. As specimen height increases, a plastic hinge develops in this region under load. In shorter specimens, the inner and outer tubes interact in a nearly fixed-end condition, without failure of the connecting pins. All three specimens failed by instability, and reducing the specimen height significantly enhanced the load-bearing capacity. When the top of the specimen is pin-supported, the material’s compressive strength is not fully utilized. To improve the axial stability of independent scaffolding, several structural improvements are proposed: replacing the pinned top with a plate-supported end to enhance compressive stability; integrating transverse bracing at the ends to connect individual units into an integrated system, thereby improving overall stability without compromising spatial flexibility; and applying mechanical reinforcement with external collars at the inner–outer tube interface to increase local bending stiffness and reduce initial imperfection, thus strengthening the global buckling resistance of the independent scaffolding system.