Environmental Engineering Reference
In-Depth Information
Table 4.3 Partial safety factors
g
F
according to DIBt guideline [9], Table 3
Action
Design load case (DLC) group
N
normal
and extreme
A
accidental
T
transport/
erection
Inertia and gravitational loads
1.35
a)
unfavourable
1.10
1.25
favourable
1.00
1.00
1.00
prestress
c)
1.00
1.00
1.00
1.35
b)
Wind loads
1.10
1.50
Operational forces
1.35
1.10
1.50
Thermal actions
1.35
—
—
Earthquake
—
1.00
—
a)
Provided it is verified that the actual unit weights do not deviate by more than 5% from
the assumed loads, for example by weighing the machinery of the turbine installation, a
partial safety factor of
g
F
¼
1.10 may be used.
b)
The internal forces for the tower and the foundation for DLC 6.1 to Table 4.1 ([9] Table 1)
are to be calculated with both
g
F
¼
1.35 and
g
F
¼
1.50. It is not necessary to consider an
b¼
0). The most
unfavourable combination of internal forces of the two variations governs.
c)
According to DIN 1045-1 [33] 8.7.5 (3), the following must be taken into account:
If the rise in stress in the prestressing steel is taken into account in the case of unbonded
tendons, then its characteristic value
oblique angle of attack in the case of
g
F
¼
1.50 (angle of attack
Ds
pk
must be determined with the mean values of
the material properties. A value of
g
P
(
g
D
P
)
¼
1.0 applies when calculating the design
value
g
D
P
)
Ds
pk
based on a linear elastic calculation for the internal force.
An upper or lower bound must be assumed for
Ds
pd
¼g
P
(
g
P
when using a non-linear method to
determine the internal forces; the formation of cracks or the opening of joints (pre-
fabricated construction) must be considered here:
g
P,sup
(
g
D
P,inf
)
¼
0.83 (0.80)
The most unfavourable value is to be used in each case (the values in brackets apply
according to [36]).
g
D
P,sup
)
¼
1.20 (1.20) and
g
p,inf
(
4.6
Design of offshore wind turbine structures
4.6.1 Control and safety systems
The system concept for an offshore wind turbine includes control and safety systems.
The aim of the control system is to ensure that the offshore wind turbine is operated
