AXIAL COMPRESSION BEHAVIOUR OF ELLIPTICAL CONCRETE-FILLED STEEL TUBULAR LONG COLUMNS

A three-dimensional finite element analysis model for elliptical concrete-filled steel tubular long columns subjected to axial compression is developed and the corresponding tests are carried out． The predicted relationship curves of load versus deflection in the middle column height and damage modes are in good agreement with the measured results． The finite element analysis model is thus used to investigate the stress and strain distribution of each component and the interaction between the steel tube and the core concrete in the whole loading process． And then，the main parameters influencing the relationship curves of load versus deflection in the middle column height such as slenderness ratio，material strength，steel tube wall thickness and cross sectional dimension are investigated． The results show the typical failure modes of these columns were the lateral overall bending at about mid-height，the slenderness ratio have obvious effects on their mechanical behavior，while the yield strength of steel tube has slight effect on their mechanical behavior．