Experimental and numerical study on the axial compression performance of the prestressed sleeved members

Abstract

The progressive collapse of large-span spatial structures can be triggered by the buckling of compression members. To further improve the stable load capacity of compression members, this study proposes a prestressed sleeved member by combining a prestressed stayed column system with a sleeved member. The experimental results show that the prestressed sleeved members possess a high load capacity, large secondary stiffness and moderate recovery performance, with the buckling modes of the members including first-order and second-order buckling. A nonlinear finite element (FE) model for the prestressed sleeved members is developed based on the experimental model. In addition, a series of parametric analyses are conducted to investigate the effects of the initial imperfection amplitude ratio, inner tube length to slenderness ratio, strand cross-sectional area ratio, inner and outer tube cross-sectional stiffness ratio and central support plate equivalent height ratio on the axial compression performance of the specimens. Furthermore, a simplified calculation model of the prestressed sleeved members is proposed for the case of second-order buckling, and theoretical calculation formulas are presented for three key points of the axial force–displacement curves of specimens. In contrast to the theoretical and FE results, the maximum errors of axial displacement and axial force do not exceed 15%. In addition, the steel strand tension, the contact force, and the lateral deflection of the middle section of the inner half-tube are highly consistent, which verifies the proposed relevant assumptions and theoretical calculation formulae.