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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 3
Pontes de concreto armado: efeitos da corrosão e da variação do módulo de elasticidade do concreto
Figure 19 – Variation of minimum, medium and maximum longitudinal compressive stress in the top
of the slab versus
ρ
for (B-S) and (SOL) models, in cracked section, modulus of elasticity E ,
c
with impact, caused by {DEAD}, {DEAD +
φ
.TB360} and {DEAD +
φ
.TB450}, with reinforced corrosion
6940
5274
4867
3789
6971
5462
4938
3917
6980
5835
5031
4131
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
10000
DEAD-
ρ
3-TOT
DEAD+
φ
.TB360-
ρ
3-TOT
DEAD+
φ
.TB450-
ρ
3-TOT
DEAD-
ρ
3-0,6L1
DEAD+
φ
.TB360-
ρ
3-0,6L1
DEAD+
φ
.TB450-
ρ
3-0,6L1
DEAD-
ρ
3-0,0L1
DEAD+
φ
.TB360-
ρ
3-0,0L1
DEAD+
φ
.TB450-
ρ
3-0,0L1
σ
c
(kN/m
2
)
VARIATION OF THE MÍN, MÉD E MÁX COMPRESSIVE STRESS
WITH CORROSION IN THE REINFORCEMENT -
ρ
3=2,68% -
φ
=1,26
- TOP OF THE SLAB- CRACKED SECTION -
(B -
S) AND
(SOL) MODELS - EC -
(kN/m2)
(SOL)-
ρ
3-TOT-MAX
(B-S)-
ρ
3-TOT-MAX
(SOL)-
ρ
3-TOT-MED
(SOL)-
ρ
3-TOT-MIN
(SOL)-
ρ
3-0,6L1-MAX
(B-S)-
ρ
3-0,6L1-MAX
(SOL)-
ρ
3-0,6L1-MED
(SOL)-
ρ
3-0,6L1-MIN
(SOL)-
ρ
3-0,0L1-MAX
(B-S)-
ρ
3-0,0L1-MAX
(SOL)-
ρ
3-0,0L1-MED
(SOL)-
ρ
3-0,0L1-MIN
For the sections which the first layer of the reinforcement presents
a corrosion of 40%, the tensile stresses on the most requested
bars of the (SOL) model, obtained with the standard bridge-loads
TB360 and TB450, are superior to the design yield strength of re-
inforcement CA-24 steel, which start to happen with the stresses
obtained with the (B-S) model for the standard bridge-load TB450.
For the sections which the first layer of the reinforcement presents
a corrosion of 100%, the tensile stresses on the most requested
bars of the (SOL) model, obtained with the standard bridge-loads
TB360 and TB450, are superior to the design yield strength of re-
inforcement CA-24 steel, which start to happen with the stresses
obtained with the (B-S) model for the standard bridge-load TB360
and TB450.
Considering the case of load {DEAD + φ.TB450} and the mod-
ulus of elasticity E
c
the maximum tensile stress varies from
280.88 MPa, with the no corroded reinforcement, to 319.82
MPa with the first layer totally corroded, which increases the
stress intensity of 13.9% and decrease the reinforcement ratio
of 20.9%, due to the total corrosion of the first layer. With the
modulus of elasticity 0.5.E
c
, the maximum tensile stress var-
ies from 272.51 MPa, with a no corroded reinforcement, up to
352.73 MPa with the first layer totally corroded, corresponding
to 29.4%. In these cases, the maximum stress of the bars ex-
ceeds the corresponding value of the design yield strength of
CA24 steel, even considering the entire reinforcement, evidenc-
ing that these bridges do not obey the requirements imposed by
the actual standard bridge-load.
4. Conclusions
With the above, one could conclude that the compression stresses
on the concrete, coming from bending moment, had been little in-
fluenced by the cracking, by the variation of the modulus of elastic-
ity of concrete and by the corrosion of the first layer of the reinforce-
ment. In the worst situation, the highest level of the stress in the
compressed concrete reached 37.7% of its arbitrated characteristic
compressive strength or 52.8% of its design strength. For the older
bridges, with strength of concrete in the same order of magnitude
of the value arbitrated, the results obtained permit to conclude
that the compressive stresses on the concrete are not a motive