Ireland Wind Standared

(1) Unless specific values are given from the meteorological service in Dublin, the direction factor is to be considered by (3) For sites up to altitudes of 250m the altitude factor is given by For altitudes more than 250m, advice may be available from the meteorological service in Dublin. Figure A3 Ireland - wind map (reference wind velocity)

United Kingdom

(1) The values of reference wind velocity vref0 at sea level are derived from q analysis. 3s where altitude above sea level m of the site when topography is not significant or else the altitude of the ground level at the base of the hill or escarpment when topography is significant (see 8.4) measured from mean sea level. (3) Values for the directional factor are given in Table A4. Use of these values for all possible wind directions gives the design overall risk of exceedence distribue-ted...

Dynamic coefficient for gust wind response

(1) Values of cd set out in Figures 9.1 to 9.8 are based on typical values of the relevant parameters and the simple equations for frequency given in annex C. For conventional structures these assumptions and equations have been found to be reasonable and the Figures provide upper bound values to cd within the field of application in the Figures. In particular the values are conservative for structures sited in categories II to IV. Caution should be exercised for special structures of unusual...

Djf

Terrain factor torsional stiffness K factor length of a horizontal structure m mass per unit length equivalent mass per unit length n exponent ni natural frequency of the structure of the mode i 1.x fundamental frequency of alongwind vibration ni.y fundamental frequency of crosswind vibration P annual probability of exceedence In* reference mean velocity pressure averaging time of the reference wind speed, plate thickness cg onset wind velocity for galloping gig critical wind velocity for...

Info

(4) Values for the temporary factor, c , are given in Table A5. These values allow the assement of wind loads in sub-annual periods for temporary structures or structures in a temporary condition during construction. Note that using these factors results in the entire design annual risk being transferred to the sub-annual period and the user should consider whether a 0,02 risk in the sub-annual period is still appropriate. Note also that delays in construction, etc. in the summer period may...

Latin uppercase letters

Fi vortex exciting force at point j of the structure H height of a topographic feature Kfo x interference factor for buffeting, along wind response x interference factor for buffeting, along wind acceleration K interference factor for vortex shedding Km reduction factor for parapets Kw effective correlation length factor -e effective length of an upwind slope Li(z) integral length scale of turbulence Lj effective correlation length j actual length of an upwind slope Ng number of loads for gust...

Matters Specific to this Prestandard

(16) The scope of Eurocode 1 is defined in clause 1.1.1 and the scope of this part of Eurocode 1 is defined in 1.1.2. Additional parts of Eurocode 1 which are planned are indicated in clause 1.1.3. (17) This Part is complemented by a number of informative annexes. (18) The relevant wind parameters (the basic value of the reference wind velocity and various factors and parameters) shall be provided in the form of maps or otherwise (see annex A) by the Relevant Authority. The value of the...

Modelling of wind actions

(1 )P The wind action is represented either as a wind pressure or a wind force. The action on the structure caused by the wind pressure is assumed to act normal to the surface except where otherwise specified e.g. for tangential friction forces. (2) The following parameters are used several times and are defined below Ont reference mean wind velocity pressure derived from reference wind velocity as defined in 7.1. It is used as the characteristic value ce(z) exposure coefficient accounting for...

National Application Document Part A Buildings

3 Partial safety factors, combination factors and other values 5 Additional recommendations Annexes A (normative) Photographs diagrams of terrain categories B (normative) Treatment of transition between terrain categories xv C (normative) Treatment of minimum height and effect of obstructions xxiv D (normative) Directional pressure coefficients for buildings xxv E (normative) Wind structure incorporating the principles of BS 6399 Part 2 lv Tables --- B.l Values of transition factor D.l Dynamic...

Requirements for testing

(1) P If experimental tests are undertaken, they shall be carried out on a properly scaled model of the actual full scale situation. (2) The following conditions shall be satisfied - the natural wind shall be modelled to account for the variation of mean wind speed with height above grounds as appropriate to the terrain of the site, - the natural wind shall be modelled to account for the correct turbulence as appropriate to the terrain of the site.

Vertical walls of rectangular plan buildings

(1) The reference height, ze, for walls of rectangular plan buildings depends on the aspect ratio ft band is given in Figure 10.2.2 for the following three cases (a) Buildings, whose height h is less than b, shall be considered to be one part. (b) Buildings, whose height h is greater than b, but less than 2b, shall be considered to be two parts, comprising a lower part extending upwards from the ground by a height equal to b and an upper part. (c) Buildings, whose height h is greater than 2b,...

Wind forces from pressures

(1) The wind forces acting on a structure or a structural component mav be determined in two ways -as a summation of pressures acting on surfaces provided that the structure or the structural component is not sensitive to dynamic response (cd < 1,2, see section 9). (2)P The global force, Fw, shall be obtained from the following expression Fw Qre,-ce(ze)-cd-q-ABf (6.1) q force coefficient derived from section 10 reference area for q (generally the projected area of the structure normal to the...

List of references see clause

EUROPEAN COMMITTEE FOR STANDARDIZATION (CEN) and EUROPEAN COMMITTEE FOR ELECTROTECHNICAL STANDARDIZATION (CENELEC), Brussels. (All publications are available from Customer Services, BSI) ENV 1991 Eurocode 1 Basis of design and actions on structures ENV 1991 Part 1 1994 Basis of design ENV 1991 Part 2.1 1995 Densities, self weight and imposed loads ENV 1991 Part 2.2 1995 Actions on structures exposed to fire ENV 1991 Part 2.3 1995 Actions on structures Snow loads ENV 1991 Part 2.5 1997 Thermal...

Topography coefficient

1 P The topography coefficient, q z , accounts for the increase of mean wind speed over isolated hills and escarpments not undulating and mountainous regions It is related to the wind velocity at the base of the hili or escarpment It shall be considered for locations closer than half the length of the hill slope from the crest or 1.5 times the height of the cliff. It is defined by q 1 2 s- lt D for 0,05 lt d gt lt 0,3 8.3 1 0,6 s for lt j gt gt 0,3 s factor to be obtained from Figure 8.1 or...

National Application Document Part B Bridges

This National Application Document NAD has been prepared by Subcommittee B 525 10. It has been developed from a a textual examination of ENV1991-2-4 1995 b a limited parametric calibration against BS 5400 Part 2 This NAD encompasses wind actions as covered by ENV 1991-2-4. Specific UK requirements relating to loads resulting from densities, self weight and imposed loads ENV 1991-2-1 , fire actions ENV 1991-2-2 , snow loads ENV 1991-2-3 , thermal actions ENV 1991-2-5 , loads and deformations...

Ukv

10.4.2 Pressure coefficients for porous fences 1 Porous fences with solidity ratio y lt 0,8 should be treated as a plane lattice usinq the provisions of 10.10. 10.4.3 Shelter factors for wails and fences 1 When there are other walls or fences upwind that are equal in height or taller than the wall or fence height h, an additional shelter factor can be used with the net pressure coefficients for boundary walls and lattice fences. The value of the shelter factor depends on the spacing between the...

Wind maps and meteorological information

Eurocode European Wind Map

1 P The detailed wind maps and meteorological informations are given in annex A. 2 The basic reference wind velocity of Europe - an informative overlook - is given in Figure 7.2. Figure 7.2 European wind map indicative values only Note 1 The final wind velocities will be defined by the national authorities during the ENV-period in accordance with the format of this Part. 2 Detailed information at the present state is given in annex A

Reference wind velocity

1 P The reference wind velocity, vref, is defined as the 10 min mean wind velocity at 10 m above ground of terrain category II see Table 8.1 having an annual probability of exceedence of 0,02 commonly referred to as having a mean return period of 50 years . 2 P It shall be determined from ref CDIR ' STEM ' calt ' ref.o 7-2 vref 0 basic value o the reference wind velocity as given in annex A Co,R direction factor to be taken as 1,0 unless otherwise specified in annex A c temporary seasonal...

Roughness coefficient

1 P The roughness coefficient, cr z , accounts for the variability of mean wind velocity at the site of the structure due to - the height above ground level - the roughness of the terrain depending on the wind direction. 2 P The roughness coefficient at height z is defined by the logarithmic profile q z kT In zfzo for zmin lt z lt 200m 8.2 kT terrain factor Zq roughness length z minimum height These parameters depend on the terrain category as given in Table 8.1. 3 At heights more than 200 m...

Canopy roofs

1 Canopy roofs are roofs of buildings, which do not have permanent walls, such as petrol station canopies, dutch barns, etc. 2 The degree of blockage under the canopy is shown in Figure 10.3.1. It depends on the solidity ratio tp, which is the ratio of the area of possible obstructions under the canopy divided by the cross area under the canopy, being both areas normal to the wind direction. q gt 0 represents an empty canopy, lt p 1 represents the canopy fully blocked with contents to the down...