Civil Engineering Reference
In-Depth Information
Different FRC properties for structural applications can be obtained using
different
bers materials. From the post-cracking residual strength of the composite,
design constitutive laws are obtained [
2
].
For structural applications with normal and high-strength concrete the material
classi
cation is based on the post-cracking residual strength.
A minimum mechanical performance of FRC is needed for structural use. Fibers
improve durability and the behavior at SLS because they reduce crack width and
crack spacing. Fibers also improve ULS because they substitute partially or totally
conventional reinforcement. Unless a high percentage of
bers do not
change elastic properties nor compressive strength (Fig.
3.1
), but they can modify
mechanical properties [
2
].
In uniaxial tension, Fiber Reinforced Concretes (FRC) can show hardening or
softening behavior depending of their composition (Fig.
3.2
). Deformations are
localized in one crack when FRC has a softening behavior (Fig.
3.2
a). On the other
hand, multiple cracking occurs before reaching the peak load in the case of
hardening behavior (Fig.
3.2
b).
bers is used,
120
Plain Concrete (HSC)
100
80
FRC
60
40
Plain Concrete (NSC)
20
FRC
0
1
2
3
4
5
6
7
8
-3
Strain (10 )
Fig. 3.1 Main differences between plain and ber reinforced concrete having both normal and
high strength under uniaxial compression [
2
]
P
P
P
P
P
Crack formation
P
P
Crack formation
Crack localization
Crack localization
P
cr
cr
Fig. 3.2 Softening (a) and hardening (b) behavior in axial tension [
2
]
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