Literature Survey on Shear in FRC Beams - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 16

Table 3.1 Partial safety
factor [ 2 ]

Material Partial safety factors

FRC in compression As plain concrete

FRC in tension (limit of linearity) As plain concrete

FRC in tension (residual strength) γ F = 1.5

f Ftsd ¼ f Ftsk =c F ð 3 : 6 Þ

f Ftud ¼ f Ftuk = c F

ð 3 :

7 Þ

The recommended values for the partial safety factors are given in Table 3.1 .
For serviceability limit states (SLS), the partial factors should be taken as 1.0.

3.3 Fibers Effects on Shear Behavior

3.3.1 Fibers Concept

Fibers can be considered as reinforcement spread out all over the depth of a
structural element [ 3 ].

3.3.2 Effect of Fibers on Shear Strength and Stiffness

Steel bers increase the shear strength [ 4 , 5 ] and the load corresponding to the rst

crack [ 4 ].
The effectiveness of bers to increase shear strength is dependent on several

factors related to: matrix properties, ber properties (materials properties, aspect

ratio, and shape), bers [ 6 ].

In 1987, Narayanan and Darwish [ 7 ] claimed that ultimate shear strength increased
in higher rates when higher values of

ber content, and bond stress versus slip response of

ber aspect ratio were used but, using higher

ber content resulted in little improvement in shear strengths. On the other hand,
other authors claimed the opposite. In fact, other authors like di-Prisco et al. [ 8 ],
Lim et al. [ 9 ], Oh et al. 10 ] and Conforti [ 11 ] found that the shear strength of concrete
beams could be increased signi

cantly even incorporating low amounts of steel

bers. Conforti [ 11 ] also ensured that bers can alter the mode of failure of the

structural elements from shear to exure enhancing ductility and bearing capacity.

Other authors link the increase of shear strength to the volume of

fl

bers.

Greenough and Nehdi [ 12 ] ensured that a volume of steel bers equal to 1 % can

increase shear capacity up to 128 % with respect of reference beams, on the other
hand, Dinh et al. [ 6 ] ensured that beyond volumes of 1 % the increase in shear