Civil Engineering Reference
In-Depth Information
Table 8.9
Range of parameters in shear database of prestressed beams with only
bers (N = 26)
Parameter
Minimum
Maximum
Average
CoV (%)
d (mm)
226.47
738.89
440.93
48.79
a/d
2.84
4.40
3.40
11.15
f
cm
(MPa)
35.90
77.00
55.38
22.78
f
R3
(MPa)
2.83
8.61
4.95
39.19
Amount of
bers (kg/m
3
)
50
70
55
12.61
ρ
(%)
0.41
5.82
2.23
92.52
˃
c
(MPa)
2.87
12.00
7.16
50.05
A
s
ʱ
/s (cm
2
/m)
-
-
-
-
8.5.3 In
uence of the Residual Tensile Strength
(CMOD = 2.5 mm), f
R3
fl
Reinforced beams with f
R3
> 5 MPa present low SM. Shear stresses increases when
f
R3
also increases for both, reinforced and prestressed beams. It can be observed that
the slopes are different between reinforced and prestressed beams, due to the effect
of prestressing which also produce higher shear stresses (Fig.
8.10
).
8.5.4 In
uence of the Amount of Longitudinal
Reinforcement,
fl
ρ
l
In Fig.
8.11
, experimental shear stresses are represented versus the longitudinal
reinforcement percentage. As it can be observed, no trend is detected in reinforced
beams while, in prestressed beams, when
ρ
l
increases also the shear stress increases.
Fig. 8.10
Experimental shear
stress versus f
R3
for beams
reinforced only with bers
12.00
Reinforced beams
Prestressed beams
10.00
8.00
6.00
4.00
2.00
0.00
0.00
2.00
6.00
8.00
10.00
12.00
4.00
f
R3
(MPa)
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