Documentation

This document contains all National annex values, which are used in SDF - Basic package

Clause 4.2 Basic values, paragraph (1)P

Fundamental values of the basic wind velocity, vb,0, shall be determined from the wind zone according to the attached map

Wind region Wind velocity
[m/s]
1 22
2 24
3 26
4 28

Clause 4.2 Basic values, paragraph (2)P, NOTE 1

Statistical analysis of meteorological data in France showed no influence of altitude on the reference wind speed.

Clause 4.2 Basic values, paragraph (2)P, NOTE 2

The directional factor cdir can be obtained according wind zone and the azimuth of the wind.

cdir = 1,0 if wind blow from the different azimuth than is defined in table.
Wind region Applicable azimuth
cdir		 Directional factor
cdir
1 10 ° - 150 ° 0,70
2 70 ° - 150 ° 0,70
3 50 ° - 250 ° 0,85

Clause 4.2 Basic values, paragraph (2)P, NOTE 2

The directional factor cdir can be used for temporary cosntructions in season from April to September.
It can be obtained according direction zone map.

Season region April to September October to March
0,8 1,0
0,9 1,0

Clause 4.3.1 Variation with height, paragraph (1), NOTE 1

The different procedure is given in the Clause 4.3.3

Clause 4.3.1 Variation with height, paragraph (1), NOTE 2

Additional charts or tables are not stated.

Clause 4.3.2 Terrain roughness, paragraph (1)

The recommended procedure for determination of the roughness factor cr shall be used.
However different terrain categories are used.

Table 4.1 - Terrain categories and terrain parameters
Terrain category z0
[m]		 zmin
[m]
0   Sea or coastal area exposed to sea winds; lakes and bodies of water flown by the wind over a distance of at least 5 km. 0,005 0,1
II   Open country, with or without a few isolated obstacles (trees, buildings, etc..) Separated from each other by more than 40 times their height 0,05 2
IIIa   Countryside with fences; vineyards; farmland; dispersed housing 0,20 5
IIIb   Urbanized areas or industrial; dense farmland; orchards 0,5 9
IV   Urban areas with at least 15% of the surface is covered with buildings whose average height is greater than 15 m; forests 1,0 15

Clause 4.3.3 Orography,, paragraph (1)

The orography coefficient is cO = 1,0 or the different procedure than A.3 should be used.
Procedure 1:
a) The local average altitude of the terrain surrounding construction Am is calculated

where:
AC is the height of the construction site.
AN1, AE1, AS1, AO1 is the altitude at points in the four cardinal directions (north, east, south, west) at a distance of 500 m from the construction site.
AN2, AE2, AS2, AO2 is the altitude at points in the four cardinal directions (north, east, south, west) at a distance of 1000 m from the construction site.

b) The relative altitude of the building ΔAC is calculated.
ΔAC = AC - Am

c) The orography coefficient cO is calculated.
for z ≥ 10 m
cO = cO(10) for z ≤ 10 m
where z is height above the ground in meters.

Limitations:
1) In the case where the calculation leads to cO ≤ 1,0, disable detailed orographic calculation procedure and use cO = 1,0
2) In the case where the calculation leads to cO ≥ 1,15, detailed numerical modelling or wind tunnel experiment is necessary and coefficient should be taken with caution.

Procedure 2:


a) The value Φ is calculated as Φ = H/Lu
b) Effective length according Φ is calculated.
L = Lu/2 for Φ < 0,25
L = 2 • H for Φ > 0,25
c) The coefficients Smax, α and kred are selected from the table.
Table 4.7 NA - Parameters relating to the calculation of the coefficient orographic
Type of the obstacle Smax α kred
X < 0 X > 0
Hills chain 2,2 • H/L 3 1,5 1,5
Cliffs and escarpments 1,3 • H/L 2,5 1,5 4
Isolated hills 1,6 • H/L 4 1,5 1,5

d) Orography factor cO is calculated for Φ ≥ 0,05.

Clause 4.3.5 Closely spaced buildings and obstacles, paragraph (1)

Calculation of hdis can not be used.
hdis = 0 m

Clause 4.4 Wind turbulence, paragraph (1), NOTE 2

The value of the turbulence factor ki is calculated as follows:
for orography terrain used in Procedure 1
for orography terrain used in Procedure 2

Clause 4.5 Peak velocity pressure, paragraph (1), NOTE 1

The recommended rule for determination of qp shall be used.

Clause 4.5 Peak velocity pressure, paragraph (1), NOTE 2

The recommended value of air density is ρ = 1,225 kg/m3

Clause 6.1 General, paragraph (1)

The construction coefficient cscd is usually not separated.

Clause 6.3.1 Structural factor cscd, paragraph (1), NOTE 3

The Procedure 1 stated in Annex B shall be used.

Clause 7.2.1 General, paragraph (1), NOTE 2

The recommended procedure given in Standard shall be used.

Clause 7.2.2 Vertical walls of rectangular plan buildings, paragraph (2), NOTE 2

The recommended procedure given in Standard shall be used.

Clause 7.2.3 Flat roofs, paragraph (4)

The recommended values given in Standard should be used.
In the case of a parapet height hp / h > 0,10, it is permissible to use the coefficients for hp / h = 0,10

Clause 7.2.4 Monopitch roofs, paragraph (3)

The recommended values given in Standard should be used.

Clause 7.2.5 Duopitch roofs, paragraph (3)

The recommended values given in Standard should be used.

Clause 7.2.6 Hipped roofs, paragraph (3)

The recommended values given in Standard should be used.

Clause 7.2.8 Vaulted roofs and domes, paragraph (1)

The recommended procedure given in Standard shall be used.

Clause 7.3 Canopy roofs, paragraph (6)

The recommended distance given in Standard shall be used.

Clause 7.4.1 Pressure coefficients for free-standing walls and parapets, paragraph (1)

The recommended values given in Standard should be used.

Clause 7.4.3 The value of the horizontal eccentricity, paragraph (2)

The recommended value of the horizontal eccentricity e given in Standard should be used.