Civil Engineering Reference
In-Depth Information
The maximum shear resistance is greater than the design shear force and so the analysis
of the strut in the concrete is verified.
V
Rd
;
max
989
:
8kN
V
Ed
;
red
;
max
464
:
6kN
When analysing the load-carrying capacity of the internal shear links, or rather the tie,
the design shear force to DIN EN 1992-1-1 [20, 21] section 6.2.1 (8) may be taken as
V
Ed
;
red
;
s
V
Ed
p
Ed
?
a
i
d
489
:
0
122
:
25
?
0
:
10
0
:
653
384
:
7kN
As a simpli
ed approach, the analysis at this point uses the same strut angle as for the
analysis of the strength of the strut in the concrete. When analysing the tie, the smaller
strut angle leads to a lower load-carrying capacity, which therefore lies on the safe side.
The shear resistance (limited by the yield stress of the shear reinforcement) is calculated
using DIN EN 1992-1-1 [20, 21] Eq. (6.8).
?
z
?
f
ywd
?
cot
A
sw
s
V
Rd
;
s
θ
0
:
503
?
0
:
9
?
653
?
435
?
1
:
67
215
:
0kN
The design shear force is greater than the resistance of the shear reinforcement, so the
analysis
of the tie is
not satis
ed
and shear strengthening will be required.
V
Rd
;
s
215
:
0kN
V
Ed
;
red
;
s
384
:
7kN
6.6.2 Shear strengthening
Externally bonded full shear wrapping made from grade S235JR steel, nominal
dimensions
t
Lw
=
6mm and
b
Lw
=
80mm at a centre-to-centre spacing
s
Lw
=
600mm,
will be used for the shear strengthening. The yield stress of grade S235JR steel
according to DAfStb guideline [1, 2] part 2 is
f
yk
=
0.8
235 N/mm
2
=
188 N/mm
2
,
and the modulus of elasticity
E
Lw
=
200 000 N/mm
2
.
The additional shear force that can be accommodated is calculated according to DAfStb
guideline [1, 2] part 1 Eq. (6.108):
A
Lw
s
Lw
?
z
?
f
Lwd
?
cot
V
Rd
;
Lw
θ
The area of shear strengthening is calculated according to DAfStb guideline [1, 2] part 1
Eq. (6.109):
A
Lw
s
Lw
2
?
t
Lw
?
b
Lw
s
Lw
2
?
6
?
80
600
1
:
6mm
2
=
mm
The capacity of the shear strengthening
f
wLd
is determined depending on the material
and the type of strengthening. As the downstand beam to be strengthened is a T-beam,
only full wrapping is permitted according to DAfStb guideline part 1, RV 6.2.6 (RV 2).
The strength of full wrapping in steel is the minimum of the yield stress and the stress
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