Design of strengthening measures with externally bonded CFRP strips - Strengthening of Concrete Structures with Adhesively Bonded Reinforcement - page 23

impractical for manual calculations. However, this analysis is relatively well suited to
computer calculations because case distinction is hardly necessary.
3.3.3.4 Simpli ed analysis of element between cracks
A simpler option given in the DAfStb guideline [1, 2] for analysing the bond of the
externally bonded reinforcement is to limit the change in the force in the strip, as is
shown schematically in Figure 3.7.
In this analysis it is only necessary to verify that the change in the strip force does not
exceed a constant resistance value at any point in the member. This resistance value,
represented by the dotted line in Figure 3.7, was determined via a numerical approach
to the more accurate method for the limits prescribed in DAfStb publication 592 [9]
(q.v. [70]), the background to this being to separate resistance from action in order to
be able to use the superposition principle again. The proposal for this analysis in the
DAfStb guideline is Equation 3.36, which again depends on the bond coef cients and
the length of the element between cracks. In addition, the equation depends on the
Fig. 3.7 Scheme for analyses to be carried out for ultimate strain in strip and change in force in strip
in concrete element between cracks (simpli ed analysis)