BEHAVIOUR OF CFST COLUMN SUBJECTED TO SUSTAINED LOADING AND CHLORIDE CORROSION

Abstract

CFST stands for concrete filled steel tube column. The steel tube serves as the primary load carrying member, providing the necessary strength and stiffness to resist compressive forces. The concrete filling within the tube adds to the column’s load-bearing capacity and enhances its structural performance. corrosion in CFST column causes various detrimental effects such as reduction in steel cross-sectional area available to resist loads, this reduction directly affects the columns load-carrying capacity. Bond loss reduces the composite action between steel and column, resulting in decrease in load transfer capability. As corrosion progresses, making CFST column more susceptible to lateral buckling under applied load. corrosion also causes weakening of steels mechanical properties such as yield and tensile strength. To study the effects of corrosion on load carrying capacity of column a mechanics model using finite element analysis is carried in ABAQUS to full-range analysis on the behaviour of CFST square column under long-term loading and corrosion including load-displacement relationship. A confinement factor, which is used to characterise the composite action between the steel tube and filled concrete, is presented. The ultimate strength and ductility of CFST columns will decrease as the level of corrosion increases. This is how it can be explained: Under corrosion, the sectional size and confinement factor of the CFST specimens will decrease. As a result, the inner concrete and outer steel tube will no longer be as strong. The loss of confinement will also reduce the column's ductility. The main parameters varied in the tests are (1) Grade of steel, (2) Grade of concrete, (3) Rate of corrosion (non-corrosion, medium rate corrosion (thickness loss=0.6mm), High rate corrosion (thickness loss=1.2mm). the results indicate large reduction in ultimate load carrying capacity of column.