Wind Load of Wind Turbine Tower.

1. WIND TURBINE TOWER
LOADINGS
CALCULATION

2. Tower Specification
 Structural Steel JIS SS400.
 Ultimate Strength 415 MPa.
 Yield Strength 230 MPa.

3. Dead Loads
 Dead loads consist of the weight of all
materials of construction incorporated
into the structure (i.e. tower and wind
turbine).

4. Wind Loads
 Wind loads are
randomly applied
dynamic loads.
 It depends on the
wind speed, shape
and height of the
structure and
topographic of the
region.
 Most calculations
using US customary
systems, which is
applicable to ASCE
7-02 and ASCE 7-
05.

5. Assumption
Components Assumption for Analysis
Tower Cylindrical Poles
Wind Turbine Lattice Frameworks (Є= 0.36)

6. Basic Wind Speed, V
and Wind Directionality Factor,
Kd The basic wind speed, V, assumed as
134.216 mph or 60 m/s.
 The wind directionality factor, Kd, for
wind turbine tower is 0.95 for tower
and 0.85 for the DS wind turbine.

7. Importance Factor, I
 An importance
factor, I, for the
wind turbine tower
(Building Category
III or IV) is 1.15.
Building Type I
Category I -
Buildings and other
structures with low
hazard to human life
in the event of
failure, such as
agricultural facilities.
0.77
Category II – Other
buildings.
1.00
Category III and IV -
Buildings and other
structures with a
substantial hazard to
human life in the
event of failure, such
as hospitals,
communication
towers and power
generating stations
1.15

8. Surface Roughness and
Exposure
 It is assumed that
the tower would be
installed on a
terrain with surface
roughness and
exposure category
of C (town/ small
city).
Exposure
Category B,
ex. 臺北
Exposure
Category C,
ex. 板橋
Exposure
Category D,
ex. 金門

9. Velocity Pressure Exponent
Coefficient, Kz
 Velocity pressure
exponent, Kz, depe
nds on the site
relative height to
the ground, z.
 This means for
rooftop
structure, z, would
be the total height
of the component
and the building its
installed.
Nominal height
above ground level,
z
K z for
Exposure
C
ft m
0-15 0-4.6 0.85
20 6.1 0.90
25 7.6 0.94
30 9.1 0.98
40 12.2 1.04
50 15.2 1.09
60 18 1.13
70 21.3 1.17
80 24.4 1.21
90 27.4 1.24
100 30.5 1.26

10. Topographic Factor, Kzt and
Force Coefficient, Cf
 The value of Kzt
was taken as 1 with
assumption flat
region
environment.
 The values of Cf
were taken from
Figures 6-19 and
6-21 of the code.
 The values are 1.2
for the tower and
1.1 for the wind
turbine.

11. Velocity Pressure, qz
 The velocity pressure, qz, evaluated at
height z shall be calculated by:

12. Gust Effect Factor, G
 Gust effect factor, G, could be
calculated by Eq. 6-4 of the code.
 This factor increased with structure
height.

13. Design Wind Loads, F
 Design wind force for
each component shall
be determined by:
 Moment because of
wind force calculated
as:
FWT
FTOWER
a
b
bFaFM WTTOWER