EN 40-3-1-2013 pdf download.Lighting columns – Part 3-1 : Design and verification pecification for characteristic loads.
V is the 10 minute mean wind velocity at 10 m above ground level for terrain category II (see Table 1) having an annual probability of exceedence of 0,02 (commonly referred to as having a mean return period of 50 years).
= CALT V.ef,O
is the basic value of the reference wind velocity at 10 m above sea level obtained from the wind maps referred to in Annex A:
CAI_T is an altitude factor to be taken as 1,0 unless otherwise recommended in the National Annex to EN 1991-1-4
p is the air density. The air density is affected by altitude and depends on the temperature and pressure to be expected at the site location during wind storms. The value of p shall be taken as 1.25 kg/m3, unless otherwise recommended in the National Annex to EN 1991-14.
C is a factor to convert V,5 from an annual probability of exceedence of 0,02 to other probabilities, and can be derived from the formula given in Annex A. For lighting columns the normal requirement is for a mean return period of 25 years, for wtiich the factor C, should be taken as
5.2.3 Factor for column size
The greater the size of a surface subject to wind, the more unlikely It is that the maximum pressure, on which the calculation is based, acts over its full area.
The resultant smaller wind load on a component is taken into account by the factor 6 dependent on the size of the area.
The ruling dimension for the size of the area subject to the wind is the greatest dimension in one direction.
For a lighting column, this is the nominal height in metres.
The value of the factor 6 shall be obtained from the formula:
8 = 1 – 0,01 h
5.2.4 Factor for the dynamic behaviour of lighting columns,
The factor is dependent upon the basic period of vibration T and the damping of the columnliuminaire” system and takes into account the increase in the load, resulting from the dynamic behaviour of the lighting column, caused by wind gusts.
5.2.5 Topography factor f
The topography factor F shall be taken as 1, unless topography is specified as significant.
Where a topographic feature is significant. the methodology in EN 1991-14:2005, Annex A should be used.
The altitude used for calculating CALT shall be the altitude at the base of the topography slope in the upwind
direction.
5.2.6 Exposure coefficient c.(z)
The exposure coefficient accounts for variation of wind pressure with respect to height above ground and depends on terrain category.
The appropriate terrain category br the location of the lighting column shall be decided on the basis of Tablet 1.
5.3.3 Shape coefficients for columns and brackets with other cross-sections
For cross-sections other than circular and regular octagonal. the shape coefficient c shall be taken from
EN 1991-1-4 or shall be based on reliable test results.
5.3.4 Shape coefficient for luminaires
It is recommended that the horizontal shape coefficient and the vertical lift coefficient for luminaires, resulting from wind In the horizontal direction, should be determined from wind tunnel tests. The maximum values obtained in the test for luminaire inclinations between ± 50 to the horizontal shall be adopted.
Vertical wind loads on the luminaires shall only be considered when their effect will be additional to the loading condition being considered, i.e. where they do not provide a relieving effect to the member stresses.
In the absence of values determined by wind tunnel tests, or given by the luminaire supplier, a single horizontal coefficient of 1,0 shall be adopted.
The lift coefficient shall then be taken as zero. Where there is a cluster of luminaires, a corresponding shape for the cluster shall be taken into account.
6 Forces and moments
6.1 Forces due to wind pressure and dead load
6.1.1 Hoiizontal force on any part of the column shaft
The horizontal force, in N, on any part of the perpendicular column shaft shall be calculated using the following formula:
FAcq(z) (3)
where
F is the partial horizontal force, in N. due to wind pressure acting at the centre of the area of the section of the column shaft being considered:
is the projected area, in m2, on vertical plane normal to the direction of the wind, of the
section of column shaft being considered:
c is the shape coefficient for the section of the column shaft being considered:EN 40-3-1-2013 pdf download.