Volume 3, Issue 1, December, Pages11-24

Research Article:

 Dr. Ragheed Fatehi Makki

 Department Of Civil Engineering, Engineering College, University of Kufa

E-mail addresses: Ragheed.Almutwali@uokufa.edu.iq

ABSTRACT

No-Fine concrete filled double steel tube columns (CFDST) are being increasingly used for
structural applications. It has been used for submerged tube tunnels, nuclear containment,
liquid and gas retaining structures, vessels under external pressure in very deep water and for
compression members in offshore construction, this is due to the aesthetic appearance, ease of
maintenance and simple of construction. The (CFDST) columns also have excellent resistance
to seismic loads and fire. This paper comprises of an experimental study on the structural
behavior of double steel tubular columns filled with No-Fine concrete under axial load. Eight
samples of double steel circular tubes with different diameters for the inner and outer tubes
are used, with different slenderness ratios (L/r), different ultimate strengths of No-Fine
concrete ( f c′). Also two cases are study for (CFDST) samples first with hollow inner tube and
second with completely filled inner and outer tubes with No-Fine concrete.
The experimental results show that the effect of height (the slenderness (L/r) ratio) on the
ultimate strength of CFDST columns will have a reverse relation. While the effect of uniaxial
compressive strength ( fc′) and the effect of fully filling the core of internal tube on the ultimate
strength of CFDST columns will have an increase relation.

Keywords: No- Fine Concrete, Compression Members, Concrete Filled Double Steel Tubes
(CFDST)

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