This study examines the axial load capacity of circular Concrete Filled Steel Tube
columns using High Strength Concrete (CFST-HSC). Emphasis is drawn to the
enhanced axial capacity of short columns attributed to the lateral confinement of the
concrete infill provided by the steel encasement. The degree of confinement has been
found to be dependent on several geometric and mechanical parameters. At present,
significant discrepancies exist with respect to quantifying the effective strength confined concrete. Existing design models and codes are predominantly derived from
the characteristics of normal strength concrete and therefore may be inappropriate concrete filled steel columns utilising High Strength Concrete (HSC).
An extensive experimental program was initiated to examine the axial capacity of
CFST-HSC columns. The results of 62 concentrically loaded scale model columns filled
with High Strength Concrete (46-100 MPa) are presented. The principal experimental
parameters were concrete and steel strengths, tube diameter to wall thickness ratio, column slenderness ratio. The columns tested were classified as short thin walled
sections and were tested as isolated column elements under short term loading. The
results are compared with the predictions of several existing design procedures and
recommendations are proposed.