Page 162 - Riem-Vol6_nº3

507 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
F.M. ALMEIDA FILHO | M. K. EL DEBS | A.L.H.C. EL DEBS
According to Figure 13, the stress behavior on the contact surface
and in the concrete elements was almost the same. The point 1
presented the same behavior for both cases while the points 9 and
17 presented a significant difference, showing that the concrete el-
ements have a gradual transfer of stresses, because the stress at
point 9 is higher than at point 17. Also, the stress calculated by the
contact elements at point 17 was higher than the stress on point 9.
Figure 14 shows the comparison between the stresses from the
test results of the strain gages placed on the steel bar and the
numerical results.
As expected, according to Figure 14, the test results from the
strain gages showed that the strains at the steel bar were linear
for both models, showing that the numerical result led to a satis-
factory approach.
4.2 SCC2 and OC2 series
Figure 15 shows the variation of the bond stress at the steel-con-
crete interface during the substep of the failure load.
Figure 16 shows the principal stresses at the cross section nor-
mal direction for beam numerical models. Also, the details of each
beam without the steel bar and the steel hinge are shown.
According to the numerical results, the variation of the stress-
es at the steel bar can be observed, for both cases. Also, the
stress at the steel-concrete interface shows a gradual varia-
tion, from the start of the development length until the other
edge. Figure 17 shows the stress variation of the concrete and
contact elements.
According to Figure 17, for both models with 10 and 16 mm, the
general behavior was the same. The concrete elements present-
ed the same behavior for the points 1 and 17, while the point 9
presented significant differences in its behavior. For the contact
elements, it appears that only the point 1 resists to the steel bar
sliding, because, for the other points, the calculated stresses were
around zero. Figure 18 shows the comparison between the stress-
es from the tests results for the strain gages placed on the steel bar
and the numerical results.
As expected, due to the high strength of the concrete, the results
of the strain gages showed that the strains at the steel bar were
non-linear for both models, showing that the numerical results led
to a satisfactory approach (Figure 18).
4.3 Analysis of the bond behavior between
the series
According to the numerical results, the bond stress measured by
contact and concrete elements assumed similar values for nor-
mal concrete compressive strength, while for high strength con-
crete there was high difference, mainly provoked by the contact
elements.
According to Figure 11, the bond stress shows that there was a
decreasing of its magnitude along the development length, but the
Figure 10 – Measurement points on the
bonded zone and on the steel bar
. śĂ▓ 
P3 P2 P1
P1 P11 P6 P1 P17 P9
10 mm steel bar
16 mm steel bar
5
Steel bar
points of
Bonded zone
measurement
points of
measurement
Figure 11 – Stress distribution for the beam models
0 2 4 6 8 10 12
-30
-25
-20
-15
-10
-5
0
Concrete elements
Contact elements
Measurement points
S tr ess (c onc re te ) (M P a) -30
-25
-20
-15
-10
-5
0
10 mm steel bar
St re ss ( con tac t) ( MP a )
0 2 4 6 8 10 12 14 16 18
-30
-25
-20
-15
-10
-5
Concrete elements
Contact elements
Measurement points
St re ss (c on cr et e) ( M P a) -30
-25
-20
-15
-10
-5
16 mm steel bar
S t re ss ( co nt ac t) ( MP a)