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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
P. M. LAZZARI | A. CAMPOS FILHO | F. P. S. L. GASTAL | R. A. BARBIERI | R. C. SCHWINGEL
Table 12 – Load cases for verification of Serviceability Limit State
Cases
Load cases
Initial date (days)
Final date (days)
Load cases
1
2
3
4
Weigth T shaped + prestressing
Permanent load (g + M + M )
1g
2g
Time effects
Variable load (q + M + M )
1q
2q
28
28
28
10,000
28
28
10,000
10,000
kN/m (rare combination) for the French norm. Flexural moments M
1
and M
2
used to evaluate SLS-W were M1 = 337 kN.m and M2 = 379
kN.m (frequent combination) for the Brazilian norm, and M1 = 468
kN.m and M2 = 526 kN.m (rare combination) for the French norm.
The member was analyzed on day 28, considering prestressing
only on the section T, and then adding permanent loading (g + M
1g
+ M
2g
). Between days 28 and 10,000, the effects of yield, shrink-
age, and relaxation on the total sections were calculated. After the
analysis of structural behavior relative to time, the last loading por-
tion was added on day 10,000, corresponding to the reduced vari-
able load (q + M
1q
+ M
2q
).
After the processing stage, results were analyzed in a post-pro-
cessing stage. Firstly, input data of the example, such as material
properties, are shown in Figure 32. These input data are common
to service limit state evaluations performed according to the Brazil-
ian and French norms, and were printed, except for the values of
the modulus of elasticity of concrete.
Figure 33 shows a table with the results of the forces correspond-
ing to normal stress, shear strength, and flexural moment along
the element.
Figure 34 presents normal forces due to prestressing and shear
strength along the element. Figure 35 shows the flexural moment
relative to loading (frequent combination) and applied prestressing
graphs, as well as the total moment graph, representing the sum
of the first two graphs. As a parabolic profile was considered for
the active reinforcement plotted in the normal force, prestressing
moment and total moment graphs, the curve is clearly identified in
the prestressing tendons.
Figure 36 presents a table with the cracking width values of all
sections, as evaluated according to the Brazilian norm (w
k
, w
k1
, and
w
k2
). Figure 37 shows the strain graph of each passive reinforce-
ment layer and the limit strain recommended by the French norm.
Figures 38 and 39 show the cracking tables calculated according to
the Brazilian and French norms, respectively. Concrete structural
behavior at each horizontal plane of each section of each element is
indicated by the values 9, 2, 1, 0, -1, and -2, as shown in the figures.
Figure 33 – Cross-section forces (kN, cm) - Brazilian code specification (frequent load combination)