EN 1991-1-4 : Wind actions Prof EN 1991-1-4 : Wind actions Prof. Pierre SPEHL Technical Control Bureau for Construction www.seco.be

Contents of EN 1991-1-4

1.1 Scope

Storm of 25 Januari 1990

4. Basic wind velocity vb

Fundamental value vb,0 of the basic wind velocity

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

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

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

Annex A : Terrain roughness (categories III & IV)

4.3. Mean wind velocity vm(z)

Table 4.1 : Terrain parameters

Figure 4.1 : Assessment of terrain roughness

Transition between roughness categories

Upstream distance x (m) (National Annex of Belgium, France & Luxembourg)

Orography factor co

Wind deviation around a building

Neighbouring structures

4.5. Peak velocity pressure qp(z)

Exposure factor ce(z)

5.2. Wind pressure on surfaces

Reference height for external pressure ze (Figure 7.4)

Reference height for external pressure ze (Figure 7.4)

Zones for vertical walls (figure 7.5)

External pressure coefficient cpe for vertical walls (figure 7 External pressure coefficient cpe for vertical walls (figure 7.2 & Table 7.1)

Conical vortices (flat roof)

Zones on a monopitch roof (figure 7.7)

External pressure coefficient cpe for monopitch roofs (Table 7.3a)

Conical vortices (duopitch roof)

Wind tunnel testing (Central station Antwerp)

5.3. Wind forces

7.6. Force coefficient cf (figure 7.23 & 7.24)

Plane lattice structure with angle members (figure 7.33)

End effect factor yl (Figure 7.36)

6. Structural factor cscd

Annex D : Structural factor

6. Structural factor cscd

Background factor B²

Resonance factor R²

Aerodynamic admittance function

Power spectral density function SL (figure B.1)

Peak factor kp (figure B.2)

Vortex shedding (Annex E)

Critical wind velocity vcrit,i

Viaduc de MILLAU

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