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EN 1991-1-4 : Wind actions

Prof. Pierre SPEHL Technical Control Bureau for Construction

www.seco.be

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Contents of EN 1991-1-4

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1.1 Scope

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Storm of 25 Januari 1990

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4. Basic wind velocity vb

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Fundamental value vb,0 of the basic wind velocity

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Wind velocity measured in BEAUVECHAIN airport (Belgium) on 25 Januari 1990 (knots)

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Wind velocity measured in BRUSSELS (Belgium) on 25 Januari 1990 (knots)

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Annex A : Terrain roughness (categories 0, I et II)

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Annex A : Terrain roughness (categories III & IV)

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4.3. Mean wind velocity vm(z)

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Table 4.1 : Terrain parameters

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Figure 4.1 : Assessment of terrain roughness

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Transition between roughness categories

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Upstream distance x (m)

(National Annex of Belgium, France & Luxembourg)

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Orography factor co

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Wind deviation around a building

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Neighbouring structures

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4.5. Peak velocity pressure qp(z)

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Exposure factor ce(z)

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5.2. Wind pressure on surfaces

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Reference height for external pressure ze

(Figure 7.4)

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Reference height for external pressure ze

(Figure 7.4)

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Zones for vertical walls (figure 7.5)

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External pressure coefficient cpe for vertical walls

(figure 7.2 & Table 7.1)

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Conical vortices (flat roof)

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Zones on a monopitch roof (figure 7.7)

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External pressure coefficient cpe for monopitch roofs

(Table 7.3a)

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Conical vortices (duopitch roof)

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Wind tunnel testing (Central station Antwerp)

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5.3. Wind forces

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7.6. Force coefficient cf (figure 7.23 & 7.24)

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Plane lattice structure with angle members(figure 7.33)

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End effect factor (Figure 7.36)

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6. Structural factor cscd

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Annex D : Structural factor

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6. Structural factor cscd

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Background factor B²

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Resonance factor R²

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Aerodynamic admittance function

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Power spectral density function SL (figure B.1)

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Peak factor kp (figure B.2)

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Vortex shedding (Annex E)

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Critical wind velocity vcrit,i

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Viaduc de MILLAU

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Thank’s for your attention