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IBRACON Structures and Materials Journal • 2012 • vol. 5 • nº 5
R. R. F. SANTOS | D. R. C. OLIVEIRA
Figure 2� � Stringer�s strain theoretical variation in section S21 due to passage
of the loaded operational train type on concrete (left) and reinforcement
Figure 2� � Stringer�s stress theoretical variation in section S21 due to passage
of the loaded operational train type on concrete (left) and reinforcement
limit state of fatigue” of Model Code MC90 (CEB-FIP, 1992) [12],
which sequentially presents three methods for design verification
with increasing levels of refinement and precision. To verify the
fatigue of concrete, the NBR 6118 : 2003 [11] brings only the most
simple and therefore more conservative method. Moreover, the
Model Code MC90 (CEB-FIP, 1992) [12] recommends the use of
the more simplified as only a preliminary analysis, if the other two
methods are not used. For this reason, although the fatigue crite-
rion of the NBR 6118 : 2003 [11] have been satisfied for the section
in question, was additionally performed a more refined analysis
according to Model Code MC90 (CEB-FIP, 1992) [12], and the re-
sults of this analysis are described below.
For the use of this more refined method, the actual Model Code
MC90 (CEB-FIP, 1992) [12] suggest the use of algorithm Rain
Flow for counting cycles. Using this algorithm can be carried out a
cycles counting of stresses in both the concrete and the reinforce-
ment. From the cycle count obtained through the algorithm can be
proceeded the fatigue analysis according to Model Code MC90
(CEB-FIP, 1992) [12]. Table 6 presents results from the fatigue
analysis for section S21, considering the operational train type and
Table 7 presents the results for the future train on the same sec-
tion. The structural damage for each element (reinforcement and
concrete) is determined independently and it is considered that
the damage in the section is the largest damage of the structural
elements individually. The lifetime is expressed in pairs of trains
(loading blocks) and in years, considering the passage of 18 trains
per day. It can be observed in the tables that the damage of the
structural elements of the section is low, except for the concrete on
the bottom surface of the section, which is very compressed. This
concrete fiber is subject to high initial stresses due to the perma-