Page 166 - Riem-Vol6_nº3

511 IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 3
F.M. ALMEIDA FILHO | M. K. EL DEBS | A.L.H.C. EL DEBS
2. The numerical models presented good approach with the test
results, mainly for the failure load and for the displacement val-
ues; however, the slip results could not be well represented.
The differences between the measured slip compared to the
numerical results reached almost 54% (B-OC-C30-B10);
3. The stress vs . strain behavior of the steel bar was well repre-
sented by the numerical approach, giving reliable results and
ensuring the numerical model can represent the test;
4. According to the stress distribution of the steel-concrete
interface, both analyzed elements types (contact elements
and concrete elements under the contact surface) showed
similar results. However, the analysis of the variation of
the stress during the test showed a better behavior when
considering concrete elements, for both concrete com-
pressive strength.
5. The strain pattern measured by test specimens showed the
main strain values in the middle of the steel bar and in the posi-
tion right before the embedment length. The numerical models
showed the same behavior, but with inferior values that those
obtained by test specimens. This may be explained by the yield
limit established for the steel bar, which reduced the strain of
the steel bar in the numerical models.
Finally, the utilization of numerical models to represent the bond
behavior in a beam test, using ordinary concrete (OC) and self-
compacting concrete (SCC), presented a good approach, showing
that the concrete type did not affect the bond response, since the
materials’ properties were similar. Also, according to the results,
Figure 18 – Comparison between the test results from the strain gages and the numerical result
the adopted parameters could be extended for others models with
different compressive strength and other bar diameters.
6. Notation
t = Bond stress, MPa;
tu = Bond stress at the failure load, MPa;
Pu = Failure load, kN;
k = Assumes 1.25 for f < 16 mm and 1.50 for f ≥ 16 mm;
ss = Steel bar stress, MPa;
ld = Development length, mm;
D = Displacement applied by the piston during test, mm;
fs = Steel bar diameter, mm;
fc = Concrete compressive strength, MPa;
su = Slip at the failure load, mm;
du = Maximum beam vertical displacement, mm;
l = Experimental vs. numerical ratio;
fo = Cylinder concrete compressive strength, MPa;
e = Strain caused by the fc concrete stress, ‰;
eo = Strain at cylinder concrete failure, ‰;
FKN = Normal contact stiffness factor;
FKT = Tangent contact stiffness factor.
7. Acknowledges
To CAPES, CNPq and FAPESP for the financial support. Also,
the technical staff at the Structures Laboratory, and to the com-