Calculation of wind load on circular cylinders

Eurocode 1 Wind load on circular cylinders (force coefficient)

Description:

Calculation of wind load action effects on circular cylinder elements. The total horizontal wind force is calculated from the force coefficient corresponding to the overall effect of the wind action on the cylindrical structure or cylindrical isolated element

According to:

EN 1991-1-4:2005+A1:2010 Section 7.9.2

Applicable for:

Cylindrical structures, isolated cylindrical elements

Supported National Annexes:

Only countries that adopt CEN recommended values for sections 7.9.2 and 7.13 of EN1991-1-4 are supported. The value of the peak velocity pressure can be specified manually. Otherwise automatic calculation of peak velocity pressure is supported, in addition to countries that adopt the CEN recommended values for NDPs, also for the following National Annexes: Finland, Portugal. The National Annexes of Germamy, Norway, Spain, Sweden, Switzerland are NOT supported (enter peak velocity pressure manually).

Hint: Select 'Custom peak velocity pressure' in the terrain category dropdown in order to manually specify the peak velocity pressure.

Terrain category

The terrain categories are illustrated in EN1991-1-4 Annex A. The transition zones between terrain categories are specified in EN1991-1-4 §A.2.

Illustration of Terrain categories reproduced from EN1991-1-4 Annex A

Basic wind velocity

v_b

m/s

The basic wind velocity is given as v_b = v_b,0⋅c_dir⋅c_season where the fundamental value of basic wind velocity v_b,0 is defined in EN1991-1-4 §4.2(1)P and its value is provided in the National Annex. Altitude correction may also be specified in the National Annex for EN1991-1-4 §4.2(2)P. The directional and season factors are generally c_dir = 1.0 and c_season = 1.0. For particular cases values smaller than 1.0 may be specified in the National Annex for EN1991-1-4 §4.2(2)P.

Peak velocity pressure at reference height

q_p(z_e)

kPa

Diameter of the cylindrical element

Length of the cylindrical element

Maximum height above ground of the cylindrical element

Surface type

Orography factor at reference height z_e

c₀(z_e)

Orography factor larger than 1.0 may be applicable over isolated hills and escarpments. See EN1991-1-4 §4.3.3 and §A.3 for more details.

Structural factor

c_sc_d

Structural factor c_sc_d in accordance with EN1991-1-4 Section 6. A value of c_sc_d = 1.0 is generally conservative for small structures not-susceptible to wind turbulence effects such as buildings with height less than 15 m or chimneys with circular cross-sections whose height is less than 60 m and 6.5 times the diameter.