Environmental Engineering Reference
In-Depth Information
c) maximum, similar to DIN 1045-1 [33] Eq. (76):
v
Rd
;
max
;
F
¼
c
j
=
0
:
50
v
Rd
;
max
where
a
c
f
cd
cot
v
Rd
;
max
¼
b
u þ
tan
u
In components with shear reinforcement, v
Rd,c
and v
Rd,max
must be reduced at least up to a
distance of L
e
¼
0.5
cot
u
d on both sides of the joint.
Interaction between bending and torsion in the joint between the elements can be taken
into account in the bending design by adding a differential tensile force
D
N
Ed,T
to the
respective design value of the normal force N
Ed
; the former depends on the associated
torsion action effect t
Ed
- similar to DIN 1045-1 [33] Eq. (92):
D
N
Ed
;
T
¼
t
Ed
u
k
cot
u
F
4.7.4.3 Detailed design
The capacities of the cross-sections are verified according to DIN 1045-1 [33]; for
details see Section 4.7.1. The concrete strength design value, for example for a C 50/60
concrete, is
f
cd
¼
0
:
85
50
=
1
:
50
¼
28
:
3 MPa
The partial safety factor for the concrete compressive strength should be increased by
10% because of the possible drop in strength near the joints, see DIN 4227-3 [63]:
f
cd
¼
0
:
85
50
=
1
:
65
¼
25
:
8 MPa
4.7.4.4 Transferring prestressing forces
Transverse tensile forces N
w
,Ed
in the circumferential direction occur at the force
transfer zones above and below the prestressing points and the spacers (Figure 4.20):
N
w;
Ed
0
:
10
F
p
;
max
Radial change-of-direction forces h
Ed
are thus mobilised and these cause bending
action effects m
s,Ed
at the edges of the shell [64]:
h
Ed
¼
N
w;
Ed
=
r
m
r
m
k
s
r
m
s
r
m
e
k
m
s
;
Ed
¼
h
Ed
sin
k
The hoop tension forces N
w
,Ed
can be accommodated by tangential reinforcing steel,
the bending disturbances m
s,Ed
by vertical U-bars.
4.7.4.5 Erecting and prestressing precast concrete elements
The precast concrete elements are bedded on plastic spacers in fresh mortar joints. The
tendons are generally prestressed as a whole from their upper ends (Figure 4.21).
