Civil Engineering Reference
In-Depth Information
Table 4.6
Comparison of admissible change in strip force and change in strip force due to
action.
Element
Δ
F
LEd
Δ
F
Lk,BL
Δ
F
Lk,BF
Δ
F
Lk,KF
Δ
F
LRd
Δ
F
LEd
/
Δ
F
LRd
—
kN/m
kN/m
kN/m
kN/m
kN/m
—
1
2.38
5.39
7.37
21.95
23.14
0.10
2
7.11
5.77
7.22
21.52
23.00
0.31
3
11.72
6.51
6.92
20.24
22.45
0.52
4
16.12
7.90
6.37
18.14
21.61
0.75
5
20.15
10.68
5.27
15.26
20.81
0.97
6
7.18
12.14
4.69
11.69
19.02
0.38
7
6.98
13.95
3.97
9.99
18.61
0.38
8
7.94
16.63
2.91
8.24
18.52
0.43
9
8.87
20.75
1.28
6.27
18.87
0.47
10
9.77
27.17
0.00
4.11
20.85
0.47
11
7.35
32.44
0.00
1.75
22.79
0.32
strip force at the less heavily stressed crack edge of the element and thus have to
be recalculated for every element. Table 4.6 compares the admissible change in
the strip force with the change in the strip force due to the action at every concrete
element between cracks. Element 5 is the critical one; 97% of the bond capacity is
utilized here.
4.5.5 End anchorage analysis
Verifying the end anchorage requires an analysis at the
flexural crack closest to the
point of contra
exure according to DAfStb guideline part 1, RV 6.1.1.4.2, which is
describedhereinSection3.3.4.2.Itis
first necessary to determine the
flexural crack
that is nearest the point of contra
exure, which in the case of the simply supported
slab is the one closest to the support. To do this, the cracking moment of the cross-
section from Section 4.5.3 is compared with the moment at the ultimate limit state
after strengthening (load case 3):
p
?
x
cr
16
:
95
?
x
cr
2
p
?
l
2
?
x
cr
16
:
95
?
4
:
3
2
m
Ed
x
cr
2
?
x
cr
m
cr
Using this equation, the
flexural crack closest to the support is located at
x
cr
=
389.29
mm. Consequently, the bond length of the externally bonded reinforcement can be
calculated using the depth of bearing,
t
=
200mm (see Section 4.1.1), and the distance
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