Behaviour Of Concrete Filled Steel Tubular Column Subjected To Axial And Cyclic Lateral Loads

Abstract

Concrete filled steel tube (CFST) columns are widely used in the construction of modern buildings and bridges due to its abundant structural benefits like excellent seismic behavior, ultimate load bearing capacity, excellent ductility and energy absorption capacity, particularly in zones of high seismic area. These composite constructions combine the advantages of both steel tube and concrete, namely the speed of construction and high strength. The aim of this research was to conduct numerical study on behavior of CFST columns under axial and cyclic lateral loads using finite element software. The lateral load carrying capacity under cyclic load was investigated due to change in different parameters such as diameter to thickness (D/t) ratio, concrete compressive strength, steel grade and slenderness ratio. Proper material constitutive models for concrete and steel were used while modeling of concrete-filled steel tube and verified by the nonlinear finite element program ABAQUS against experimental data from reviewed literatures. The cross sections of the concrete filled steel tube in the numerical analysis were categorized into three groups, i.e., circular cross section, square cross-section and steel reinforced circular section. Through the numerical analyses, it has been shown that for circular concrete filled steel tubular column, the steel tube provides good confining effect to concrete especially when the diameter-to-tube thickness ratio is small. For square concrete filled steel tubular column, the tubes do not provide too much confining effect to concrete when the width to thickness ratio is large. Axial load capacity of steel reinforced-concrete filled-steel tubular column (SRCFST) has been enhanced due to introduction of reinforcing steel to undertake higher loads. Effect different parameters such as steel contribution ratio, yield strength of steel section, concrete compressive strength on lateral load capacity were carried out. Result showed that the lateral load capacity circular concrete filled steel column significantly increased by D/t ratio, increase in steel grade, decrease in slenderness ratio and slightly increase due to increase of concrete grade. From finite element analysis, SRCFST columns have higher peak lateral load and deformability than common concrete filled steel tubular (CFST) columns due to the presence of the section steel. Moreover, the result showed that circular concrete filled steel tubular columns have lighter weight, higher bending stiffness, and better cyclic performance than square concrete filled steel tubular columns.