Behaviour of elliptical concrete-filled steel tube (CFT) columns under axial compression load

This thesis describes a research of the behaviour of the elliptical CFT
columns under axial loading. The most substantial part of this research is
experimental works conducted on twenty-seven specimens including the
hollow stub columns as references. Parameters such as slenderness ratio,
uni-axial compressive strength of concrete infill and the aspect ratio were
considered to investigate their influence on the behaviour on these columns.
The results presented are the first member buckling tests on elliptical CFT
columns. Keys results from the tests have been presented and discussed.
Parallel with the experimental works, numerical analyses were carried out
and verified with the experimental results. Parametric studies were
performed following the validation of the numerical models.
As there is no design guidance seems to be available in any standard, thus
this research provides a review of the existing design standards of Eurocode
4 (EC4) and American Specifications (AISC). The design expressions from
these current design provisions for circular, square and rectangular
concrete- filled tubes design strengths were used to predict the capacities of
elliptical eFT columns. The influences of concrete enhancement, steel
reduction due to biaxial effects and column slenderness were all
incorporated in design rules of EC4. Based on the experimental, numerical
findings the evaluations were made on the design rules of the codes. This
investigation was aimed at providing reliable design guidelines for practising
engineers to employ the elliptical concrete-infill columns in the construction
industry.