WIND TURBINE TOWER LOADINGS CALCULATION

Tower SpecificationStructural Steel JIS SS400.Ultimate Strength 415 MPa.Yield Strength 230 MPa.

Dead LoadsDead loads consist of the weight

of all materials of construction incorporated into the structure (i.e. tower and wind turbine).

Wind LoadsWind 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.

AssumptionComponents Assumption for Analysis

Tower Cylindrical Poles

Wind Turbine Lattice Frameworks (Є= 0.36)

Basic Wind Speed, Vand 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.

Importance Factor, IAn 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

Surface Roughness and ExposureIt 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

Velocity Pressure Exponent Coefficient, Kz

Velocity pressure exponent, Kz, depends 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 Exposur

e 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

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.

Velocity Pressure, qz

The velocity pressure, qz, evaluated at height z shall be calculated by:

Gust Effect Factor, GGust effect factor, G, could be

calculated by Eq. 6-4 of the code.This factor increased with

structure height.

Design Wind Loads, FDesign wind force for

each component shall be determined by:

Moment because of wind force calculated as:

FWT

FTOWER

a

b

bFaFM WTTOWER