Theoretical study on the post-local buckling of steel plates in concrete-filled box columns

This paper presents a theoretical study on the post-local buckling behaviour of steel plates in welded steel box columns filled with concrete, by using the finite element method. The effects of various geometric imperfections, residual stresses and width-to-thickness ratios on the post-local buckling characteristics of steel plates in composite columns are investigated. A novel method is developed for evaluating the initial local buckling loads and post-local buckling reserve strength of steel plates with imperfections associated with a theoretical analysis. Two effective width formulas are proposed for the design of clamped steel plates restrained by concrete and are employed in the ultimate strength calculation of short concrete-filled steel box columns. The proposed design models are compared with existing experimental results with a good agreement.