Shear Database and Study of the Parameters Influencing Shear Behavior - On Shear Behavior of Structural Elements Made of Steel Fiber Reinforced Concrete - page 179

Table 8.32 ANOVA for SM on shear — type III sums of squares (f c and f R3 beams-I)
Source of variation Sum of squares d.f Mean square F-ratio p-value

Main effects
A: Compressive strength 0.104674 2 0.052337 33.81 0.0001

B: Fiber type 0.0444741 2 0.022237 14.36 0.0023

C: Code 0.101252 2 0.0506259 32.70 0.0001

Interactions
AB 0.112326 4 0.0280815 18.14 0.0004

AC 0.0126815 4 0.00317037 2.05 0.1802

BC 0.0933481 4 0.023337 15.07 0.0009

Residual 0.0123852 8 0.00154815

Total (corrected) 0.481141 26
All F-ratios are based on the residual mean square error

of surface charts (Figs. 8.35 , 8.36 and 8.37 ), it is possible to evaluate the in fl uence

of the interactions on the shear SM.
Analyzing the surface charts of this Series, it seems that all Codes give SM very
close to the unit, so they are very safe for all the combinations. RILEM and EHE
are unsafe when high strength bers (80/40BP) are used. Of the three codes, in

general, the MC2010 seems to be the safest. In general, Codes have low SM for
concretes with low compressive strength and high strength

bers (80/40BP). On the
other hand, Codes have greater SM for concretes with medium compressive
strength and bers 80/50BN.

8.7.6.2 Beams with Different Fibers Types: Analysis II

In Table 8.33 , the constant variables within the same Series are indicated. In
Table 8.34 , the input data for the ANOVA analysis is presented, differencing the
factors (independent variables) of the dependent variable (safety margin, SM). In this
case, the three factors are: compressive strength level (Medium, M; High, H),

bers
type (45/50BN, 65/40BN, 80/50BN, 80/30BP, 80/40BP) and Codes (EHE, MC2010,
RILEM), having all factors three levels. So, the number of complete cases is:

3 1 =30complete cases
The ANOVA table (Table 8.35 ) shows that all main effects and two interactions
have signi

of levels) № of factors =2 1 5 1

× ×

№ complete cases =( №

cant differences since their p-values are less than 0.05.
By means of LSD intervals (Fig. 8.38 ), in this Series, it can be observed that:

Compressive strength level. there are signi cant differences. For high com-

pressive strengths, Codes are more adjusted (less conservative).

￿

Fiber type. With bers made with normal strength bers (BN), Codes are more

￿

conservative when bers (BP),

the shorter are the more conservative for EHE and RILEM, as discussed in the
interaction plots and surface charts.

bers are slenderer and longer. For high strength