الفهرس 
ACKNOWLEDGEMENTS
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Abstract
ABSTRACT
Corrosion of steel reinforcement in aggressive environments can cause
considerable damage in reinforced concrete (RC) structures. Fiber reinforced
polymer (FRP) bars have emerged an alternative to steel for RC elements subjected
to those environments, Its non-corrosive nature has turned the attention of many
researchers to carry out several studies on different types of FRP products. Through
a vast research, several standards also have been formulated. In this regard, a new
combination of FRP materials is examined in this study and its properties have been
derived. Carbon fiber and glass fibers fuse in this study to form a new hybrid rebar.
In order to improve the structural performance of GFRP reinforced concrete
member, one alternative solution have been proposed, such as using a hybrid
reinforcement (CFRP rods and GFRP bars) as a main reinforcement. Carbon fiber
provides even higher tensile strength and more elastic modulus than steel. These are
advantageous features of using carbon fiber in a structural point of view but not in
economics, since its price is almost ten times higher than glass fiber. The concept of
“hybridization” was arisen for the FRP rebar to overcome their shortcomings. The
mechanical properties of FRP bars can yield to large crack widths and deflections.
As a result, the design of concrete elements reinforced with FRP materials is often
governed by the serviceability limit states (SLS).
This study investigates the behavior of flexural and serviceability conditions
of concrete beams reinforced with FRP bars and hybrid bar under static loads
through theoretical and experimental analysis each measuring 150 x 250 x 2036 mm.
All the studied beams tested under four-point loading. The main variables considered
in the study are the concrete grade; the reinforcement ratio and the hybridization
ratio CFRP to GFRP (ACFRP /( ACFRP +AGFRP)). Deformations on the concrete and on
the reinforcement and crack width and spacing are measured and analyzed. The
ABSTRACT
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experimental results are discussed and compared to some of the most representative
prediction models of deflections and cracking for steel and FRP RC.
Results showed that, in general Hybrid rebar showed a superior performance
in comparison with GFRP. A discussion on the main aspects of the SLS of FRP RC
is introduced. The influence of the different parameters affecting the stresses in
materials, maximum crack width and the allowable deflection is studied and
analyzed. It is reported that at a cross-section level, for lightly reinforced members,
the crack width limitation results are more restrictive than the stresses in concrete.
However, for sections with high reinforcement ratios, the predominant restriction is
the concrete stress. Because SLS result determining for the design of FRP RC beams,
a methodology is presented for the design of FRP RC at the serviceability
requirements. Crack pattern, final modes of failure, load carrying capacity, service
load, CFRP rod, GFRP and steel tensile strain, mid span deflection, concrete strain,
crack spacing, and the crack width were recorded.
The comparison between the predicted values of cracking and ultimate loads,
midspan deflection and the maximum crack width estimated using some of the
available formulae found in literature and the corresponding experimental results are
also presented in this thesis