Parametric study of composite column strength variability

Abstract

The study reported herein investigates the effects of different variables on the variability of the ultimate strength of steel—concrete composite columns in which steel shapes are encased in concrete. The ultimate strength of a number of typical composite columns was studied in terms of the ratio of ‘theoretical’ strength based on an accurate description of strength and probability distributions of variables affecting the strength to a ‘nominal’ strength based on design expressions of the American Concrete Institute Building Code (ACI 318-83) and the specified properties of the variables. This was done to non-dimensionalize the strength and to simplify the comparison of strength for different columns. The major conclusions drawn from the analysis of results reported in this study are: (a) the residual stresses play an appreciable role in the strength of composite columns; (b) the concrete confinement provided by the lateral ties produces a beneficial effect on the strength of composite columns, and (c) the specified concrete strength, end eccentricity ratio, and slenderness ratio are the major parameters affecting the variability of composite column strength.