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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 4
Post-strengthening of reinforced concrete beams with prestressed CFRP strips
Part 2: Analysis under cyclic loading
prestressed CFRP strips, damages that occur due to fatigue are
mainly related to the level of stress at the steel rebars. Experimen-
tal results showed that the damage, which led to the rupture of the
steel rebars, is related to the level of stress during loading, and,
that it is not related to the type of post-strengthening.
Tests showed that an increasing of 20% in the maximum stress
of the steel rebars significantly reduced the fatigue life time of the
post-strengthened element, decreasing about 15 times the number
of cycles up to failure. These results emphasize the importance of
proceeding the monitoring of structures that are usually submitted
to cyclic loading, such as highway and railway bridges. In some
cases, when these structures were designed to support traffic
loads smaller to the ones that they are submitted nowadays, the
use of post-strengthening may increase their lifetime, since the
use of post-strengthening may lead to a reduction in the stress
level of the steel rebars.
6. Acknowledgements
Authors would like to acknowledge CNPq (Portuguese acronym
of the Brazilian Ministry of Science’s National Research Coun-
cil) and CAPES (Portuguese acronym of the Brazilian Ministry of
Education’s Higher Education Human Resources Development
Agency) for providing the financial support needed to develop
this project. Authors would also like to express their appreciation
for the technical support given by the research team at EMPA
(Swiss Federal Laboratories for Materials Testing and Research),
in Switzerland.
7. References
[01] MENEGHETTI, L. C. ; GARCEZ, M. R. ; SILVA FILHO,
L. C. P. ; GASTAL, F. P. S. L. Fatigue life regression
Figure 15 – CFRP and concrete strains of beam VFC_PC_02, submitted
to 78kN after (a) 1.000.000 cycles and (b) 5.000.000 cycles
A
B
Figure 16 – CFRP strains of strip 01 (a) and 02 (b) of beam VFC_PC_02 during cyclic loading
A
B