RESEARCH ON CIRCULAR TAPERED CONCRETE-FILLED STEEL TUBULAR LONG COLUMNS

A three-dimensional finite element analysis model for circular tapered concrete-filled steel tubular long columns subjected to longitudinal compression is developed and the corresponding tests are conducted． The predicted relationship curves of load versus 3 /4 height deflection，bearing capacities and failure modes have good agreements with the tested results． Based on the finite element analysis，stress and strain distribution in the whole loading process is analyzed，and interaction between steel tubes and concrete is put forward． In the meantime，the main parameters such as slenderness ratio，tapered angle，eccentricity，strength of the materials，steel tube wall thickness have been analyzed on the ultimate loads of circular tapered concrete-filled steel tubular long columns and the relationship curves of load versus 3 /4 height deflection． The results show the typical failure modes of these columns were the lateral overall bending at about 3 /4 height，the slenderness ratio，the tapered angle，the load eccentricity，the compressive strength of concrete and the steel tube wall thickness have obvious effects on their mechanical behavior，while the yield strength of steel tube has slight effect on their mechanical behavior．