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Case 3 (ONLY FIBERS). Beams ordered by kg/m
3
of fibers
2.50
300
CONSERVATIVE
2.25
250
2.00
200
1.75
1.50
150
1.25
100
1.00
50
0.75
UNCONSERVATIVE
0.50
0
kg/m3 (Reinforced beams)
kg/m3 (Prestressed beams)
SM (EHE-08)
SM (MC2010)
SM (RILEM)
Case 4 (STIRRUPS + FIBERS). Beams ordered by kg/m
3
of fibers
2.00
300
CONSERVATIVE
1.75
250
1.50
200
1.25
150
1.00
100
0.75
50
UNCONSERVATIVE
0.50
0
kg/m3 (Reinforced beams)
kg/m3 (Prestressed beams)
SM (EHE-08)
SM (MC2010)
SM (RILEM)
uence of the amount of steel bers (kg/m
3
) on shear safety margins
Fig. 8.46
In
fl
In the present work, some suggestions for improvements to existing Codes were
made. In particular, the following suggestions are proposed:
Codes are not reliable for calculating shear strength when a/d < 2.5, since the
arch action is very pronounced and shear strength provided by Codes is
markedly conservative. For proper calculation of these cases, other methods
should be used as the method of struts and ties.
The larger the crack width at Ultimate Limit State becomes, the stronger the
size-effect will be. Furthermore, it should be considered that the size factor is
in
ber length and, therefore, by the FRC toughness. The latter is a
mechanical property that better characterize the material behavior. Therefore, in
fl
uence by the
ber reinforced elements, the parameter governing the size effect should depend
on the FRC toughness in addition to the element size.
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