Experimental Tests on Parameters Influencing on Shear - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 70

Fig. 4.13 SM variations when different fl ange factor values are applied

When k f was not applied (2nd option), highly conservative SM (safety margin)
values were obtained (Fig. 4.13 ). If the 4th option is observed (k f without limitation)
it is clear that SM is lowered for 600 mm

fl ange widths, meaning that the appli-

cation of limitations is necessary.
In Sect. 4.4.3 it was concluded that, although the beam with the smallest ange

width (b f = 260 mm) presented the lowest shear strength, it was not possible to
con

fl

ange width as no clear differences in shear
strength were observed for beams with flange widths up to 400 mm. This is in
complete agreement with the results given in Fig. 4.13 , in which the most balanced
option (when comparing the theoretical and experimental results) may be obtained
by applying the corresponding k f value (3rd option) for the cases in which
h f > 400 mm. Only the beam with a low b f value (b f = 260 mm) was not conser-
vative enough with this criterion. In this case it cannot be considered that the

rm any clear in fl uence of the fl

fl ange

width has an in fl uence on shear strength and therefore k f = 1 should be applied.

4.4.4.2 Assessment of Shear Formulations from Current Design Codes

The safety margins (SM) obtained as V test /V theo (the shear test value divided by the
theoretical shear value) were used as a reference to compare the results obtained
from the different beams and Codes.
In order to achieve a more complete analysis of the SMs of the current Design
Codes, Fig. 4.14 shows how the SMs of the different codes were plotted for the