Civil Engineering Reference
In-Depth Information
depth was made from three types of concrete with the following amount of
bers: 0,
Another aspect that has attracted interest is to know the in
fl
uence of
bers on
shear behavior of beams. It is well known that
bers give rise to more ductile
behavior with more dynamic failure modes in which,
a priori,
it cannot be made
sure which of the shear cracks that were generated will provoke the beam failure.
Furthermore, it is known that the presence of
bers results in a more distributed
cracking pattern; in fact, in FRC beams, shear cracks appear more but thinner and
closer. Another aspect to note is that Codes currently use
f
R3
to take into account the
mechanical properties concerning FRC. This has been widely studied and justi
ed,
but it is not evident that the value of
f
R3
is the one that better represents the
mechanical behavior of FRC for all combinations of compressive strength and
ber
22 FRC beams has been carried out. In this program, three different compressive
strength levels (low, medium, and high; 30, 50, and 80 MPa, respectively) have
been used. Also,
ve different types of
bers have been used, where three types of
steel
bers had normal strength (45/50BN, 65/40BN, 80/50BN) and two types of
bers were made of high-strength steel (80/30BP, 80/30BP).
After studying the literature, it was found that the addition of
bers can be very
positive in structural elements where it is dif
cult to incorporate transverse rein-
forcement such as Hollow Core Slabs (HCS), manufactured by extrusion. The lit-
erature on HCS made with FRC is very scarce; also in addition, during
manufacturing some problems raised up due to the addition of
bers. Therefore, an
experimental program was carried out on HCS made with FRC, in which no man-
ufacturing problems were detected, since the most interesting issue would be to take
advantage of the
ber for industrial use. The experiments also seek to study different
failure modes to analyze the contribution of the
bers, using different amounts of
Design Codes Used in Part III
For determining the shear strength, the most widely used international Design
Codes have been used, such as the Eurocode 2 (EC2) and the Final Draft of the
Model Code 2010 (MC2010). In this Ph.D. thesis, when MC2010 is used, it is
going to be used as its Final Draft. The Final Draft of the MC2010 proposes
formulations to determine the shear value of elements with and without
bers.
On the contrary, the EC2 does not have a formulation to determine the
ber
contribution to shear; therefore RILEM formulation is added to determine such
contribution. Furthermore, as this thesis is mainly done in a Spanish university,
shear values have also been calculated according to the Spanish Code
“
”
EHE08.
The latter is based on EC2 for the part of concrete without
bers and on RILEM to
determine
ber contribution to shear.
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