الفهرس 
LITERATURE REVIEWOnly 14 pages are availabe for public view
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Abstract
Recently, Near Surface Mounted (NSM) system presented a better
flexural behavior compared to the Externally Bonded (EB) system
due to the higher bond strength between concrete and FRP. The aim
of this work is to evaluate the ductility and moment redistribution
for statically indeterminate beam strengthened with NSM CFRP
rods. This scope is selected as the linear-elastic brittle failure
behavior of these composite materials can be a serious restriction of
assuring the required level of ductility and moment redistribution. A
three-dimensional (3D) FE model was developed, using the
computer software ABAQUS (2020), in order to validate the
flexural performance of experimentally tested beams available in
the literature. Two specimens were modelled for this purpose, one
control continuous beam without strengthening and the other
initially strengthened in bending with two 6 mm diameter CFRP
bars in both sagging and hogging regions simultaneously.The obtained results showed very good agreement with the
experimental results. A parametric study was conducted to study the
ductility and moment redistribution behavior using different CFRP
bonded lengths, FRP reinforcement ratios, retrofit patterns and steel
reinforcement ratios. The obtained results indicate that partially
bonding the CFRP bars can improve the beam’s deformability,
ductility, and moment redistribution with a slight decrease in
capacity but taking into consideration the resulting possible
premature debonding of the bars.
The unbonded regions of the CFRP bars can play the role of
increasing the section ductility due to the relatively delayed increase
of strain of CFRP bars. Hence, the section will have a higher
capability of plastic rotation that allows for higher moment
redistribution capacity. The arrangement of the CFRP bars can
change the direction of moment redistribution and significantly
affects the capacity of the beam. Also, increasing the FRP ratio
negatively affects the ductility of the section and thus the moment
redistribution ratio due to the brittle behavior of these materials.
Increasing the ratio between hogging and sagging steel
reinforcement ratios increases the hogging stiffness relative to the
sagging stiffness, which can reduce the transfer of moment from the
intermediate support region to the mid-span region. Thus, the
moment redistribution can be enhanced making use of the combined
positive effect of decreasing bonded length and decreasing steel
reinforcement ratio or CFRP reinforcement ratio between hogging
and sagging region.