Civil Engineering Reference
In-Depth Information
Fig. 3.4
Principle of bond force transfer with externally bonded CFRP strips
For the rest of the member, the bond force can be transferred by concrete elements
separated by
flexural cracks. The forces prevailing in such a concrete element between
cracks are a basic strip force at the less heavily stressed crack edge and this basic strip
force plus an additional strip force at the more highly stressed crack edge. This
additional strip force must be transferred into the member via bond.
3.3.2 Simpli
ed method
In the simplified method it is only necessary to use Equation 3.16 to check that the
ultimate strain of the strip is not exceeded:
8
<
l
0
h
0
:
04 mm
=
m
?
ϕ
s
0
:
06 mm
=
m
?
f
cm
0
:
5mm
=
m
0
:
1mm
=
m
?
<
l
0
9700 mm
?
l
0
9700 mm
ε
Ld
;
max
max
3
:
0mm
=
m
?
2
for
l
0
9700 mm
:
:
3
:
0mm
=
m
for
l
0
>
9700 mm
(3.16)
This simpli
ed analysis is based on a parametric study in [57] covering the more
accurate analysis of the change in force in the strip at the concrete element between
cracks in section RV 6.1.1.3.6 of the DAfStb guideline [1, 2], or Section 3.3.3.3 of this
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