Behavior of Biaxially Loaded Concrete-Encased Composite Columns

This paper reports the experimental test results of four small-scale concrete-encased I-shape steel columns subjected to biaxial bending moments and axial compressive load in single curvature. The composite column specimens, one short and three slender, had a square cross section. The effects of the eccentrically applied axial compressive force, slenderness of the cross section, different material properties of concrete and steel, and load-deflection and moment-curvature behavior on the maximum load capacity of a composite column were examined. The test results were compared with the analytical results of the maximum load capacity obtained from a numerical analysis. The numerical analysis uses the finite differences method to establish the relationship between curvature and deflection. A computer program to perform the numerical analysis is used for the case of composite columns. The comparative results indicate that the analytical method and computer program used to model and analyze the composite column specimens can accurately predict the maximum load capacity and deformation behavior of a pinned-ended biaxially loaded concrete-encased steel column with axial compressive load in single curvature.