This paper presents an experimental investigation on
ductility behaviour of reinforced concrete compression members,
rectangular in cross section, modified to elliptical shape in cross
section by bonding precast segment covers followed by Carbon
Fiber Reinforced Polymer wrapping (CFRP) under concentric
and eccentric loading conditions. Eighteen reinforced concrete
rectangular compression members of size 100mm×150mm in
cross section and 300mm in height were prepared using
normal-strength concrete. Reinforcement ratio was kept at
minimum, to simulate compression members that need
retrofitting. Out of eighteen specimens, nine specimens were
converted to elliptical shape in cross section. From nine
remaining rectangular specimens, three specimens retained as it
is without wrapping FRP and designated as Group1, remaining
six specimens were wrapped with one and two layers of CFRP and
designated as Group2. Out of nine elliptical specimens, three
specimens were retained as it is without wrapping FRP and
designated as Group3, remaining six elliptical specimens were
wrapped with one and two layers of CFRP and designated as
Group4. Specimens were tested upto failure under monotonic
axial compression with concentric and eccentric load conditions.
From the experimental results, it is observed that rectangular
compression members shape modified to ellipse in cross section
and then wrapped with CFRP show outstanding increase in the
ultimate load carrying capacity which may be due to increased
cross sectional area and effective confinement of FRP wrapping.
As the number of layers of CFRP increases the ultimate load
carrying capacity increases. With increase in eccentricity, the
ultimate loads of the compression members were found to be
decreased. Elliptical specimens wrapped with one and two layers
of CFRP reported exponential increase in deformation ductility
under concentric load condition and considerable increase under
eccentric load condition compared to rectangular specimens
wrapped with CFRP.