1、 Reference number ISO 4354:2009(E) ISO 2009INTERNATIONAL STANDARD ISO 4354 Second edition 2009-06-01 Wind actions on structures Actions du vent sur les structures ISO 4354:2009(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may b
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6、749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2009 All rights reservedISO 4354:2009(E) ISO 2009 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Symbols2 4 Wind actions 2 5 Wind pressure3 6 Wi
7、nd force 3 7 Site peak dynamic pressure.4 8 Exposure factor .4 9 Pressure and force coefficients.4 10 Dynamic response factor5 11 Criterion for aeroelastic instability 5 12 Methods of determination of wind loads 5 Annex A (normative) Mean velocity method7 Annex B (informative) Determination of refer
8、ence wind speed .9 Annex C (informative) Determination of exposure factors .11 Annex D (informative) Aerodynamic pressure and force coefficients 22 Annex E (informative) Dynamic response factors.40 Annex F (informative) Structures subject to critical excitation vortex resonance and aeroelastic insta
9、bility59 Annex G (informative) Mode combinations62 Annex H (informative) Wind tunnel testing 64 Annex I (informative) Computation-based methods .65 Annex J (informative) Reliability considerations.66 Bibliography67 ISO 4354:2009(E) iv ISO 2009 All rights reservedForeword ISO (the International Organ
10、ization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been establish
11、ed has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
12、 International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Pu
13、blication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such paten
14、t rights. ISO 4354 was prepared by Technical Committee ISO/TC 98, Bases for design of structures, Subcommittee SC 3, Loads, forces and other actions. This second edition cancels and replaces the first edition (ISO 4354:1997), which been technically revised. ISO 4354:2009(E) ISO 2009 All rights reser
15、ved vIntroduction This International Standard is intended for use by countries without an adequate wind loading standard and as a bridge between existing International Standards. The data in the annexes, with the exception of Annex A, whilst formally only informative, and limited to the most common
16、usage, are intended for use within the definitions in this International Standard. Additional data will be provided from time to time in ISO Technical Reports for use on the same basis. INTERNATIONAL STANDARD ISO 4354:2009(E) ISO 2009 All rights reserved 1Wind actions on structures 1 Scope This Inte
17、rnational Standard describes the actions of wind on structures and specifies methods of calculating characteristic values of wind loads for use in designing buildings, towers, chimneys, bridges and other structures, as well as their components and appendages. The loads are suitable for use in conjun
18、ction with ISO 2394 and other International Standards concerned with wind loads. In particular, this International Standard facilitates the conversion between peak and mean wind speed methodologies and covers the three main storm types, synoptic winds, thunderstorms and tropical cyclones (hurricanes
19、 and typhoons). This International Standard provides the basic methods from which to determine wind loading analytically through the determination of design pressures or orthogonal along-wind and cross-wind forces and moments for structures of simple shape and wind directionality effects, and throug
20、h wind tunnel or computational determinations of pressure, forces and moments for structures with complex shapes and wind directionality effects resulting in complex combinations of forces and moments. Structures of unusual nature, size or complexity (e.g. tall buildings, long span bridges, large sp
21、an roofs, guyed masts, offshore and moving structures) typically require a special engineering study; some guidance is given on the limitations of this International Standard in these cases. Two methods of analytical determination of design wind loads are given in this International Standard, one ba
22、sed on a peak velocity and the other on a mean velocity. Both methods can be used when dynamic response effects are important, and where they are not important only the peak-velocity method is used in this International Standard by taking the peak dynamic response factor to be unity. To simplify pre
23、sentation, the method based on the peak velocity is given in the main body of this International Standard and the method based on the mean velocity is given in a normative Annex A. 2 Normative references The following referenced documents are indispensable for the application of this document. For d
24、ated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 2394, General principles on reliability for structures ISO 4354:2009(E) 2 ISO 2009 All rights reserved3 Symbols Symbol Term Unit ATributary o
25、r local area (area of application of pressure coefficient C p ) m 2 A refReference area for force on overall structure or part of structure m 2C dynPeak dynamic response factor 1 C dyn, mMean dynamic response factor 1 C expPeak exposure factor 1 C exp, mMean exposure factor 1 C FForce coefficient 1
26、C FmMean force coefficient 1 C pPressure coefficient (time and spatially averaged) 1 C FStandard deviation force coefficient 1 F Peak force N F locPeak force on a tributary or local area N F mMean force N g Peak factor 1 g vWind speed peak factor 1 h Height m I vWind speed turbulence intensity 1 p P
27、ressure Nm 2q ref, mRegional reference mean dynamic pressure Nm 2q siteSite peak dynamic pressure Nm 2q site, mSite mean dynamic pressureNm 2V Peak wind speed ms 1V hcrCritical wind speed at the top of the structure ms 1V m Mean wind speed ms 1V ref Regional peak reference wind speed (with return pe
28、riod) ms 1V ref, m Regional mean reference wind speed ms 1V siteSite peak velocity ms 1V site, mSite mean velocity ms 1 F Standard deviation of force N 4 Wind actions Wind actions that shall be considered in the design of the structure can produce the following: a) excessive forces or instability in
29、 the structure or its structural members or elements; b) excessive deflection or distortion of the structure or its elements; c) repeated dynamic forces causing fatigue of structural elements; ISO 4354:2009(E) ISO 2009 All rights reserved 3d) aeroelastic instability, in which motion of the structure
30、 in wind produces aerodynamic forces augmenting the motion; e) excessive dynamic movements causing concern or discomfort to occupants or onlookers; f) effects of interference from existing and potential future buildings. NOTE Wind pressure and force given in this International Standard are equivalen
31、t static wind loads and not pure external excitations. As the equivalent static wind loads are essentially based on linear elastic building and structure behaviour, it is necessary to give careful attention if they are applied to design in the plastic region. 5 Wind pressure For the actions referred
32、 to in Clause 4 a), b), c) and e), the effective wind pressure, p, shall be determined from a relationship incorporating the site dynamic pressure, q site , defined in Clause 7 and Clause 8, a pressure coefficient, C p , and a dynamic response factor, C dyn , of the general form of Equation (1): p =
33、 q site C p C dyn(1) The wind pressure is assumed to act statically in a direction normal to the surface of the structure or element, except where tangential frictional forces are specifically identified. Both internal and external pressures shall be considered. Integration of pressures shall be und
34、ertaken to obtain global forces or forces for defined tributary areas. The effects of wind from all directions shall be considered. 6 Wind force For some structures, it may be appropriate to represent the wind forces, F, by their resultants. These resultants shall include along-wind (drag), cross-wi
35、nd (lift), torsional and overturning actions. Different magnitudes and distributions of the wind force can be necessary to evaluate the actions described in Clause 4 a), b), c) and e). The derivation of effective wind forces on an element, or resultant forces and moments, shall be determined by usin
36、g either the peak reference dynamic pressure given here, or the mean reference dynamic pressure given in Annex A. The peak reference pressure method assumes that the dynamic effects can be represented by a maximum or peak loading effect based on a peak reference pressure combined with a mean pressur
37、e coefficient, (or mean pressure coefficient modified for local effects relating to area of application and statistical characteristics), and a peak dynamic response factor, C dyn , from the general relationships given in Equations (2) and (3): F loc= q site C p C dyn A (2) F = q site C F C dyn A re
38、f(3) Equation (2) is used for the force on a tributary or local area, A. Equation (3) is used for the total force on the whole structure or part of the structure. The value of C dyncan be taken as 1,0 except where the structure is dynamically wind-sensitive, as described in Annex E. In many cases to
39、tal loads on whole structures will be determined from loads determined for various components, or facades, or from along-wind and cross-wind components. These forces contribute simultaneously but are not usually well correlated. Methods for determining load combinations are given in Annex G. ISO 435
40、4:2009(E) 4 ISO 2009 All rights reservedIt is important when using the dynamic method that the ways in which the equivalent static wind forces are distributed include not only the mean and fluctuating (background) wind forces acting on the structures exterior, but also the inertial forces due to mot
41、ions of the structures mass. 7 Site peak dynamic pressure The site peak dynamic pressure, q site , shall be determined from the regionally derived reference wind speed, V ref , along with appropriate exposure factors, C exp , relating to wind speed for the site defined by the expression: q site= 0,5
42、 (V site ) 2(4) In Equation (4) the peak design wind speed locally at the site, adjusted for local exposure conditions, is given by Equation (5): V site= V refC exp(5) where the exposure factor is determined as described in Clause 8. The reference wind speed is normally the specified value of the wi
43、nd speed for the geographical area in which the structure is located. It refers to a standard exposure (i.e. roughness, height and topography), averaging time and probability of excedence in one year (which can be approximated by an average return period for design application as required from servi
44、ceability to ultimate limit state determinations). In some situations, the reference wind speed can be specified as varying with direction. In the annexes of this International Standard the standard exposure is at 10 m height in open country terrain and q siteis based on a maximum 3 s mean gust wind
45、 speed, V. Analysis procedures and values are given in Annex B and Annex C. In certain cases, critical loading can occur at wind speeds differing from, and perhaps lower than, that specified above (e.g. due to vortex shedding). These critical wind speeds (with reference to height h) are denoted V hc
46、rand substituted for V site . These cases are discussed in Annex E. 8 Exposure factor The exposure factor, C exp , relating to wind speed, accounts for the variability of the wind speed at the site of the structure for each storm type, due to a) the height above ground level, b) the roughness of the
47、 terrain (including change of roughness), and c) the topography. Values of the exposure factor are given in Annex C, and can vary with wind direction. Further guidance on the application of directional design wind speeds is given in Annex C. 9 Pressure and force coefficients A pressure coefficient,
48、C p , is an aerodynamic wind-induced pressure expressed as a fraction of the reference pressure. A force coefficient, C F , is an aerodynamic wind-induced force expressed as a ratio of the aerodynamic force exerted on a structure or its parts to a reference pressure multiplied by a reference area. P
49、ressure coefficients are specified as appropriate fractile values of the respective extreme actions. The fractile value to be used is defined in Annex D. ISO 4354:2009(E) ISO 2009 All rights reserved 5Pressure and force coefficients are influenced by the shape of the structure, the exposure, the relative wind direction, the Reynolds number and the averaging time. Values of pressure and force coefficients are presented in Annex D in tables as non-simultaneous values for the design of cladding or parts of the structure and i
