Behavior Of Concrete Filled Square Thin-walled Steel Tubular Composite Columns

Behavior and mechanism of concrete filled square thin-walled steel tubular composite(CFSTWSTC)beam-columns subjected to monotonic loading were investigated.Based on parameter analysis,simplified models were proposed to predict the load-carrying capacities of the composite members under axial compression,bending or eccentricial compression.The following studies were carried out:(1)A series of tests under axial compression,bending and eccentricial compression are carried out.The main experimental parameters were the diameter-to-thickness ratio,diameter-to-width ratio,eccentricity and slenderness ratio.(2)The finite element(FE)soft ABAQUS was used to simulate the whole loading process for composite specimens under the axial compression,bending and eccentricial compression.The predicted results agree well with the test results.(3)The load-deformation curves of the different components,stress distributions of steel and concrete,confinement and failure modes were analyzed using the FE model.(4)Parametric analysis for the load-deformation curve and N-M interaction was performed using the FE model.The selected parameters were the diameter-to-thickness ratio,diameter-to-width ratio,steel ratio,strength of the materials,eccentricity and slenderness ratio.(5)Based on the above mechanical and parametric analysis,simplified models were proposed to predict the strength for the composite specimens under axial compression.bending or eccentricial compression.