Experimental Tests on Parameters Influencing on Shear - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 69

Table 4.6 Shear contributions (%) due to stirrups, concrete and bers according to the current
design codes (without safety factors)
Specimen ID EHE08 EC2 + RILEM MC2010
Stirrups Concrete Fibers Stirrups Concrete Fibers Stirrups Concrete Fibers

HF600TR/1 46 33 21 74 0 26 47 53

HF600TR/2 46 33 21 74 0 26 47 53

H600TR/3 58 42 0 100 0 0 56 44 0

HF600/4 0 63 37 0 61 39 0 100

HF600/5 0 63 37 0 61 39 0 100

HF400h/6 0 63 37 0 61 39 0 100

HF400/7 0 64 36 0 62 38 0 100

HF400/8 0 64 36 0 62 38 0 100

HF260/9 0 68 32 0 66 34 0 100

4.4.4.1 Flange Effect on Shear Strength

Some authors [ 14 18 ] have studied the effect of fl ange width on shear capacity with

-

“ and T-beams. Zsutty [ 17 ] proposed an equation to calculate the shear carried by

concrete with a factor h f (

I ”

ange thickness). However he considered it reasonable to
ignore the strengthening effect of the

fl

ange for design purposes. Current Design
Codes do not include this effect in their formulation for plain concrete members.
However, in the RILEM model factor (k f ) takes into account the

fl

fl ange contribution

to shear due to bers appearing.

The k f factor in Codes EHE08 and RILEM, which takes into account ange

contribution in the T-sections calculated by the formula in Introduction to Part III,
is equal to 1 for rectangular sections and increases when there is a

fl

fl ange. With the

cases presented here, k f is equal to 1.5 for fl ange widths of up to 400 mm and we

detected no fl ange effect among the beams in the present study with fl ange widths

of these sizes. In contrast, k f equaled 1.35 for the smallest fl ange width tested

(260 mm).
In Fig. 4.13 , the EC2 safety margins were plotted for the steel ber-only beams.

In this graph, the theoretical values were obtained with the EC2 formulations, and
the RILEM proposal was added to evaluate the shear contribution due to steel

bers
(EC2 formulations do not include the k f factor, but it is included in RILEM). Four
different options were therefore calculated:

1. k f = 1.5.
2. k f =1.
3. k f was applied exactly as proposed in the RILEM approach.
4. k f was applied as proposed in the RILEM approach, but without its limitations
(see Introduction to Part III).