Abstract
FRP reinforcement may be externally bonded to the soffit of existing
flexural members in order to increase their strength and rigidity.
A parametric analysis is conducted to investigate the effects of
FRP reinforcement on serviceability, strength, and failure mechanisms
of repaired RC beams. FRP reinforcement parameters considered in
the analysis are: stiffness, bonded length, thickness, and the adhesive
stiffness. The choice of the repair material parameters is important
in the design phase in order to obtain the desired results of strengthening
or stiffening without other unforeseen effects. In this paper, three
typical RC beam cross sections are considered with height-to-width
ratios of 0.5, 1, and 4. Two characteristic compressive strength
levels (20 and 30 MPa), and two shear span-to-reinforcement depth
ratios (4.5 and 7) are considered. All other parameters related to
material and geometry of the beams are maintained constant. The results
of the analysis are shown in terms of repaired-to-un-repaired strength
and deflection ratios. They indicate that brittle failure mechanisms
can develop at loads much lower than expected when considering only
flexural performance controlled by concrete crushing and FRP tensile
rupture. The analytical model used for the parametrization accounts
for brittle failure mechanisms induced by debonding of the FRP reinforcement
or shear-tension failure in concrete in the plane of the main longitudinal
steel reinforcing bars. Even when considering the limitation of the
RC member due to its un-modifiable shear resistance, it is shown
that the application of FRP reinforcement can considerably increase
load resistance capacity and limit deflection at service.
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