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- Process to calculate wind actions
- Wind structural factor cscd
- Wind zones France
- Wind zones Belgium
- Wind zones UK
- Orography factor
- Terrain categories

- Snow zone per commune in France
- Snow zone in Switzerland (SIA)
- Snow zone in Belgium
- Snow zone in UK
- Eurocode Snow loads

Eurocode General procedure - Eurocode Actions
- The Eurocodes

- Seism zone France
- Seism zone Belgium
- Seism zone United Kingdom
- Seismic importance class
- Eurocode Seismic actions General procedure

- Eurocode Permanent loads and storage loads

densities by material - Eurocode Imposed loads

tables by usage

- Eurocode Materials
- Eurocode Steel structures EN1993 General rules
- Eurocode Timber structures EN1995 General rules
- Cold rolled steel structures

The structural factor takes into account the absence of pressures simultaneity to the surface of the construction and of vibration of the structure caused by the turbulence.

The c_{s}c_{d} calculation is based on the building dimensions, construction location and the terrain's categories.

A minimum approved value of c_{s}c_{d} = 0.85 is indicated in Appendix D.

EN 1991-1-4 §6.3.1 - Detailed procedure for structural factor c_{s}c_{d}

EN 1991-1-4 Annex B - Procedure 1 for determining the structural factor c_{s}c_{d}

In France (NF EN 1991-1-4/NA clause 6.3.1 (1) NOTE 3):

The procedure to use is the procedure 1 described in Annex B. Annex B is normative; Annex C does not apply.

In Belgium (NBN EN 1991-1-4 ANB §6.3.1 (1) NOTE 3):

The procedure 1 of Annex B recommended to calculate c_{s}c_{d} is normative.

In United Kingdom (BS EN 1991-1-4 NA.2.21):

The recommended procedure given in BS EN 1991-1-4:2005 Annex B should be used.

An approched value of the structure's fundamental frequency can be calculated from:

- for a building height up to 28m, equation 4.6 of Eurocode 8 - Earthquakes:

This expression takes into account the nature of the structure (C_{t}) and its free vibration height (H). - for construction height upper than 28m, equation F.1 of Eurocode 1 part 1-4 - Wind:

This expression only takes into account the free vibration height (H) of the structure.

This is the standard deviation of wind turbulence divided by the average wind speed. It gives a mesure of the wind in the form of gusts. The recommended calculation procedure is given in EN1991-1-4 4.4(1) and the national annexes.

This coefficient reflects the lack of pressure correlation on the construction. The recommended calculation procedure is given in EN1991-1-4 B.2(2) and the national annexes:

with:

- h = total height of the building (in m)
- b = perpendicular dimension of the building to the wind (in m)
- L(z
_{s}) = turbulence scale according to EN1991-1-4 B1(1):- Lt = reference scale (300m)
- zt = reference height (200m)

This coefficient reflects the effect of turbulence in resonance with the considered vibration mode of the building. The recommended calculation procedure is given in EN1991-1-4 B.2(5) and the national annexes:

with:

- δ = logarithmic decrement of damping according to EN1991-1-4 Equation F.15:
- δs = logarithmic decrement of structural damping (0.05 for steel building, 0.06 for timber building, 0.10 for reinforced concrete buildings)
- δa = logarithmic decrement of aerodynamic damping for the fundamental mode (can be securely taken to 0)
- δd = logarithmic decrement of damping due to special devices (0 if no special device)
- S
_{L}(z_{s},n_{1,x}) = non-dimensional power spectral density function according to EN1991-1-4 B.1(2): - f
_{L}(z_{s},n_{1,x}) = non-dimensional frequency according to EN1991-1-4 B.1(2): - R
_{h}and R_{b}= aerodynamic admittance functions according to EN1991-1-4 B.2(6).

This factor is the ratio of the maximum value of the fluctuating part of the response to its standard deviation. The recommended calculation procedure is given in EN1991-1-4 B.2(3) and the national annexes:

with:

- ν = up-crossing frequency
- T = averaging time for the mean wind velocity, T=600 seconds.

The recommended calculation procedure is given in EN1991-1-4 6.3.1(1) and the national annexes:

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