r - The Hong Kong Polytechnic University

and delaying or avoiding low-cycle fatigue rupture of the steel tube. Exponential tests were conducted for
columns under cyclic lateral force with constant axial load, and the superior performance of CCFT was
validated. Figure 5 compares the column end moment and lateral displacement skeleton curves of CFT and
CCFT model columns along with the demonstration of final failure patterns.
Figure 4 Concept of CCFT
Column End Moment (kNm)
C2-CCFT3
C1-CFT3
500
400
300
200
100
0
-10 -8 -6 -4 -2-100
0 2 4 6 8 10
-200
-300
-400
-500
Drift Ratio (%)
CCFT
CFT
Figure 5 Comparisons of CFT and CCFT behaviors
(b)
(c)
(a)
Figure 6 Transversely confined steel column: (a) critical locations with confinement, (b) H-shape section
confined by steel strips, and (c) H-shape section confined by reinforced concrete
TRANSVERSELY CONFINED STEEL COLUMNS
The transverse confinement concept was recently extended to the design of stronger and more ductile steel
columns by the author. Under cyclic loading, steel columns shape such as H-steel (or W steel) may develop
post-yielding local buckling in the potential plastic hinge region. The buckled elements are straightened during
the reverse loading, and such repetitive buckling and straightening process significantly reduces the low-cycle
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