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IBRACON Structures and Materials Journal • 2013 • vol. 6 • nº 1
Automation of the evaluation of bonded and unbonded prestressed concrete beams, according to brazilian
and french code specifications
Based on the cracking tables of this second example, most sec-
tions were still completely compressed at the end of SLS evalua-
tion. It was observed that, according to both Brazilian and French
norms, most lower and central fibers were still compressed (-1), dif-
ferently from the upper fibers, close to the supports, which already
showed some cracking (2). In the central section, between hori-
zontal planes 1 and 5 (French norm), there was another cracked
concrete zone (2), and the passive reinforcement layers were still
not tensioned. Therefore, crack width was determined only for the
upper edge of the regions close to the beam ends, where passive
reinforcements of layers 4 and 6 were already tensioned.
In the SLS-W analysis according to the Brazilian norm, out of the
35 sections along the element, crack width values were calculated
only for the six sections located at the beam ends (sections 1, 2
and 32 to 35). The maximal crack width value found in the analysis
(w
k
= 0.01016 mm) was lower than that established by the Brazil-
ian norm (w
k,lim
= 0.2 mm), thereby ensuring the member safety
regarding SLS-W.
A similar situation was observed in the evaluation of excessive strain
service limit state (SLS-DEF), with a probable sagging value equal
to 0.004, which is lower than the allowed sagging (span/250) value
of 5.17cm. According to the designer, this beam presented virtually
null sagging after total loading was applied, thereby validating the
Figure 34 – Axial and Shear forces - Brazilian
code specification (frequent load combination)
Figure 35 – Bending Moment - Brazilian code specification (frequent load combination)