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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
RC T beams strengthened to shear with carbon fiber composites
The steel transverse and longitudinal ratios are given by:
(20)
sb
A
w
sw
sw
(21)
and the transverse CFC reinforcement is:
(22)
f w
f
f
f
sb
wt
2
4.2 Instrumentation
Prior to casting the concrete, the strain gauges were attached to
the steel reinforcements to obtain strain profile along these rein-
forcements (Figures [7] and [8]). Strain gauge rosettes with dif-
ferent angles were glued on to the concrete surface (Figure [9])
to obtain the two principal strains and the inclination angle of the
main compressive strain with horizontal axis. The CFC
U
stirrups
were instrumented with strain gauges in four different locations
(Figure [10]).
A data logger was used to read and record the values given by the
strain gauges, load cells, and linear variable displacement trans-
ducers (LVTDs).
4.3 Materials
A commercial concrete supplier delivered all the concrete used in
the experimental program.
Following the cast, the beams were cured without special tech-
niques and stored in laboratory conditions until the moment of
testing. The cylinders used to establish the compressive strength
and the modulus of elasticity of the concrete were cured under the
Figure 4 – Layout of the stirrups and longitudinal strip of CFC ( in cm)
Figure 5 – External CFC U stirrups of beams:
a) VI-1 and VII-1; b) VI-2 and VII-2; c) VI-3 and VII-3
(a)
(b)
(c)
1ª CFC
layer
2ª CFC layer
CFC
Bond
reinforcement
1ª CFC layer
2ª CFC layer
3ª CFC layer
CFC
Bond
reinforcement
CFC stirrups with
one CFC layer
CFC
Bond
reinforcement