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Abstract
The main objective of this study was to examine the structural behaviour of
high strength concrete filled steel tubes under concentric and eccentric
compression loading as long columns. Both experimental and analytical
investigations were conducted.
An experimental program was carried out for testing sixteen long columns
under centric and eccentric loading. The specimens were categorized into
three groups. The first group G1 comprised eight column specimens that
were subjected to centric compression loading; the second and the third
groups, G2 and G3, consists of four column specimens each, subjected to
eccentric loading with e/D ratios of 0.3 and 0.6 respectively. The column
lengths were kept as 2500 mm and the cross-sections were circular with an
inner diameter of 100 mm. The tubes thickness varied between 3 and 5 mm.
The first three specimens considered in group 1 represent control specimens;
specimens C1 and C2 represent traditional reinforced concrete columns of
strengths 30 and 70 MPa respectively while specimen C3 represents a hollow
steel tube of thickness 3 mm. The load was applied to the entire section for
all the column specimens in the three groups. Different parameters affecting
the behaviour were considered in the study such as filling concrete strength,
steel tube thickness and adding interior steel reinforcing bars to the concrete
core.
CHAPTER (8) CONCLUSIONS
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Finite element modelling, using ABAQUS v6.7 program, was constructed for
all specimens in the three groups to extend understanding of the behaviour of
concrete filled tubes. Different models were performed to study the effect of
different parameters as illustrated before. Eccentrically loaded models were
also performed to study the effect of load eccentricity on the behaviour.
After verifying the FE models constructed to simulate the columns in a
realistic way. Additional models were performed using the program in order
to include additional parameters not considered in the experimental study
such as slenderness ratio effect on the ultimate capacity of columns. Also
comparing the FE results with different codes in order to investigate the
consistency of different codes. Investigating the effect of increasing the
column’s slenderness ratio on the concrete core strength enhancement due to
confinement