Mechanical analysis and design recommendation for thin-walled OSCFST stub columns under axial local compression

摘要

Oval-shaped concrete-filled steel tubular (OSCFST) columns hold promising prospects for use as piers in bridge engineering owing to their superiority in terms of structural efficiency and flow smoothness. Although the piers are generally subjected to axial local compression, few investigations have been conducted to explore the mechanical properties of locally-loaded thin-walled OSCFST columns. To address this research gap, a simplified numerical modelling of an OSCFST stub column under axial local pressure for evaluating its typical failure patterns and mechanical performance is presented in this paper. More importantly, a simplified equivalent constitutive model for the oval-shaped concrete core in compliance with the Mohr Coulomb model is provided owing to the obscure cognition with respect to this area. Furthermore, the finite element (FE) model is validated against reported experimental data of the axially-loaded and locally-loaded OSCFST stub columns; a detailed parametric analysis in terms of the effect of material and geometric parameters is conducted. Several crucial points, including the failure modes, sectional compressive stress, and stress response of the thin-walled OSCFST stub column under axial local compression, are presented to better understand its mechanical properties. Finally, design recommendations for properly assessing the local compressive strength of the OSCFST stub column were made in compliance with the comparison between the results of the design provisions defined in specifications EC4, ALSC360-05, AU-SRC, GJB 4142-2000, and GB50936.