Axial Compressive Mechanical Behaviors of a Double-Layer Member

Abstract

The instability of structural members under axial compression most likely causes spatial structural collapse. Therefore, the configuration of double-layer members (DLMs) is proposed in this study to improve the stability of compression members. Experiments on four specimens (two single-layer members and two DLMs) were conducted, where the failure mechanism was revealed based on analysis of a validated finite-element (FE) model. Parametric studies were also performed to investigate the effects of different parameters on the compressive mechanical behaviors of the DLMs. Results showed that the desired failure mode of the DLMs was high-order buckling with torsion of the inner tube and no global buckling failure prior to contact between the outer tube and end plate (HTCG). Under the failure mode of HTCG, the ultimate load and ductility were greatly improved due to the constraint of the outer tube. Finally, predictions of the crucial loads derived from the equilibrium differential equation and empirical formula were in good agreement with the test and FE results.