Numerical Method and Experimental Study on the Ultimate Load Carrying Capacity of Four Tube CFST Latticed Columns

Abstract

The paper presents a numerical method for calculating the load-deformation response and ultimate load carrying capacity of Concrete Filled Steel Tubular (CFST) latticed columns A half-wave sinusoidal function is assumed for the deflected shape of the column. The effect of confinement and shear deformation are included in the analysis, and the corresponding equilibrium equation is established. The method applies to eccentrically loaded compression members bent in single curvature. Unequal end eccentricities can be considered. Test results are reported for seventeen four latticed column specimens with varying end eccentricities and slenderness ratios. The obtained results show that eccentricity has significant effect on the bearing capacity of specimen, and the slenderness ratio also has some influence. The diagonal lacing bars remained in the elastic state during the entire load range. When specimens go into the nonlinear stage, Poisson's ratio of the near-load steel tube increases and a significant confinement effect can be observed. For the far-load steel tube, confinement effect does not occur to a significant extent. Specimen failure is due to overall instability except in the case of several individual short columns. Good agreement was found between the theoretical and experimental results using the numerical method developed in the paper. The proposed numerical method is shown to be more accurate than the current method presented in the Chinese code.