Analysis of The results for one of the most important
experimental tests on masonry arches strengthened at their
extrados or at their intrados by fiber reinforced polymer
(FRP)strips;shows that the presence of the fibers prevents the
brittle coll
apse that occur in plain arch because of formation of
four hinges, therefore (depending on position and amount of
reinforcement) in strengthened arches, there are three possible
mechanisms : 1- masonry crushing , 2- detachment of fibers, and
3- sliding along a mortar joint due to the shear stresses. Some
analytical approaches describing these mechanisms are discussed
and a comparison between the theoretical values that give and
the experimental results was performed to show the agreements ,
according to analytical study of the experimental results
strengthening by fibers enhances the strength and ductility of
strengthened arches, the width of strips and the bond between
them and masonry are so important to perform optimum
strengthening.
This research includes an experimental study and a nonlinear
analysis using the finite element method of reinforced concrete
beams with large opening in body that exist in shear zone . The
tested beams are simply supported with rectangular section
and
without additional reinforcement in opening region. The opening is
square in shape with variable dimensions and constant distance
from the support . Studying the effect of changing length of the
opening on the behavior of the reinforced concrete beams was
already completed. The modes of cracks , (load-deflection )
relationship, ultimate load and the mode of failure for all beams
were determinate . The study showed that existence an opening in
shear region of beams reduce the strength of beams and affect on
the mode of shear failure , and any addition in the depth of the
opening lead to early cracks , more deflections and less ultimate
failure load .
This research aims to study the efficiency of flexural strengthening of RC beams with different lengths of CFRP strips by using (NSM) technique. The study is carried out experimentally on (14) concrete beams; the variables considered are (the length
and number of CFRP strips). This is established by dividing the work into two groups: the first one includes (6) beams strengthened by variable carbon fiber strip lengths and one strip, The second group includes (6) beams strengthened by variable carbon fiber strip lengths and two strips, as well as two control beams. The results indicate that carbon fibers have a noticeable effect on increasing the bearing capacity of (NSM) strengthened beams. The results also show that strengthening the beams by CFRP and not along the length of the beam and in one layer does not contribute to increasing beam strength, but when the number of layers increases, an increase in beam strength is noticed at a rate range (40%-72%).
