الفهرس 
EXPERIMENTAL PROGRAMOnly 14 pages are availabe for public view
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Abstract
Concrete filled tubes became an attractive solution for constructing
ordinary and special structures. It can provide excellent structural
properties, such as high ductility and large ultimate capacity. In addition
to the enhancement in structural properties, a considerable amount of
construction time can be reduced due to the elimination of permanent
formwork Coping with the trend of using integral bridges, the need of
using flexible columns with high ultimate capacity, to minimize the
restraining effect and sustain the expected high force levels, is increasing
rapidly. For such bridges the high strength concrete filled tubes (HSCFT)
offer a suitable solution for the substructure.
The implemented design codes, such as (EC4-1-1) are limited to concrete
strength fck = 60 MPa, and hence not appropriate for the design of
(HSCIT). This research work aimed to evaluate, experimentally and
analytically, the Behaviour of (HSCFT) subjected to eccentric loading,
with fixed - hinged boundary conditions. The chosen boundary condi tion
is simulating the real condition of the columns when used as supporting
elements for integral bridges.
In this content a total of thirteen (HSCFT) where tested under eccentric
static loading till failure. Columns having diameter to wall thickness
ratios between 33 < D/t < 50, length to tube diameter ratios of24 < LID <
28 and concrete cube compressive strength of fck= 90 and 120 MPa were
tested. The test results showed an increased capacity, when compared to
current design codes, due to the effect of concrete confinement.
The test results were used to calibrate a non-linear finite element model,
which was developed using the (ABAQUS v.6.7) software package. The calibrated model was adapted to perform a parametric study in order to
develop interaction curves for (HSCFT) with various properties. Based
on the least square technique between the numerically developed
interaction diagrams and the interaction diagrams developed using the
(EC4-1-1) equations, new analytical equations for the design interaction
diagram were developed. Finally, the result of this research work will be
combined with any other available information to formulate the basics
for the design recommendations and code limitations of such kind of
structures.