1、ANSI/ANS-2.3-2011estimating tornado, hurricane, andextreme straight line wind characteristicsat nuclear facility sitesANSI/ANS-2.3-2011ANSI/ANS-2.3-2011American National StandardEstimating Tornado, Hurricane, andExtreme Straight Line Wind Characteristicsat Nuclear Facility SitesSecretariatAmerican N
2、uclear SocietyPrepared by theAmerican Nuclear SocietyStandards CommitteeWorking Group ANS-2.3Published by theAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USAApproved April 22, 2011by theAmerican National Standards Institute, Inc.AmericanNationalStandardDesignatio
3、n of this document as an American National Standard attests thatthe principles of openness and due process have been followed in the approvalprocedure and that a consensus of those directly and materially affected bythe standard has been achieved.This standard was developed under procedures of the S
4、tandards Committee ofthe American Nuclear Society; these procedures are accredited by the Amer-ican National Standards Institute, Inc., as meeting the criteria for AmericanNational Standards. The consensus committee that approved the standardwas balanced to ensure that competent, concerned, and vari
5、ed interests havehad an opportunity to participate.An American National Standard is intended to aid industry, consumers, gov-ernmental agencies, and general interest groups. Its use is entirely voluntary.The existence of an American National Standard, in and of itself, does notpreclude anyone from m
6、anufacturing, marketing, purchasing, or using prod-ucts, processes, or procedures not conforming to the standard.By publication of this standard, the American Nuclear Society does not insureanyone utilizing the standard against liability allegedly arising from or afterits use. The content of this st
7、andard reflects acceptable practice at the time ofits approval and publication. Changes, if any, occurring through developmentsin the state of the art, may be considered at the time that the standard issubjected to periodic review. It may be reaffirmed, revised, or withdrawn atany time in accordance
8、 with established procedures. Users of this standardare cautioned to determine the validity of copies in their possession and toestablish that they are of the latest issue.The American Nuclear Society accepts no responsibility for interpretations ofthis standard made by any individual or by any ad h
9、oc group of individuals.Requests for interpretation should be sent to the Standards Department atSociety Headquarters. Action will be taken to provide appropriate response inaccordance with established procedures that ensure consensus on theinterpretation.Comments on this standard are encouraged and
10、 should be sent to SocietyHeadquarters.Published byAmerican Nuclear Society555 North Kensington AvenueLa Grange Park, Illinois 60526 USACopyright 2011 by American Nuclear Society. All rights reserved.Any part of this standard may be quoted. Credit lines should read “Extracted fromAmerican National S
11、tandard ANSI0ANS-2.3-2011 with permission of the publisher,the American Nuclear Society.” Reproduction prohibited under copyright conventionunless written permission is granted by the American Nuclear Society.Printed in the United States of AmericaForewordThis Foreword is not a part of American Nati
12、onal Standard “Estimating Tornado, Hur-ricane, and Extreme Straight Line Wind Characteristics at Nuclear Facility Sites,”ANSI0ANS-2.3-2011.!This standard is a revision to ANSI0ANS 2.3-1983, “Standard for EstimatingTornado and Extreme Wind Characteristics at Nuclear Power Sites.” The revi-sion of the
13、 1983 standard began in May of 2005. In this revision, the scope of thestandard was expanded to include hurricane wind characteristics. A change tothe Fujita damage scale as a function of wind velocities, adopted in 2007 by theNational Weather Service, resulted in the wind speeds associated with the
14、 Fujitadamage scale being replaced by the Enhanced Fujita Scale as shown in Table 1.Also included in the scope expansion is the applicability of this standard to allnuclear facility sites, not just nuclear power plant sites.This standard might reference documents and other standards that have beensu
15、perseded or withdrawn at the time the standard is applied. A statement hasbeen included in the reference section that provides guidance on the use ofreferences.This standard does not incorporate the concepts of generating risk-informedinsights, performance-based requirements, or a graded approach to
16、 quality as-surance. The user is advised that one or more of these techniques could enhancethe application of this standard.This standard was prepared by Working Group ANS-2.3 of the Standards Com-mittee of the American Nuclear Society, whose membership at the time of thestandards approval was as fo
17、llows:J. D. Stevenson Chair!, IndividualM. Amin, Sargent Codeof Federal Regulations, Title 10, “Energy,”Part 70, “Domestic Licensing of Special Nu-clear Material” 2#;andCode of Federal Regu-lations, Title 10, “Energy,” Part 830, “NuclearSafety Management” 3#.The standard does not address the determi
18、na-tion of the design basis tornado and other ex-treme wind effects for sites located outside thecontinental United States i.e., Alaska, Hawaii,Virgin Islands, Guam, and Puerto Rico! or overthe Atlantic and Pacific Oceans and the Gulf ofMexico. Such determinations should be evalu-ated on a case-by-c
19、ase basis. Additionally, thestandard does not identify the structures, sys-tems, and components that should be designedto withstand the effects of the design basisextreme or rare wind speeds and remain func-tional nor does it treat the structural designrequirements for protection from these winds.2
20、Definitionscyclostrophic wind: The cyclostrophic windis the horizontal wind velocity for which thecentrifugal force exactly balances the horizon-tal pressure gradient force. The cyclostrophicwind is a good approximation of the real windin cases of very great wind speed and strongcurvature such that
21、the centrifugal force isclearly dominant over nonpressure gradientforces e.g., Coriolis force!.design basis hurricane: The design basis hur-ricane is a postulated hurricane used for de-sign purposes only, having characteristics witha frequency of exceedence commensurate withthe facility safety goal.
22、design basis tornado: The design basis tor-nado is a postulated tornado, used for designpurposes only, having characteristics consis-tent with a frequency of exceedance commen-surate with the facility safety goal.1!Numbers in brackets refer to corresponding numbers in Sec. 5, “References.”1Enhanced
23、Fujita (EF) Scale: A rating sys-tem originally devised Fujita Scale 4#! to fa-cilitate categorizing tornadoes according to thedamage they produce and later modified En-hanced Fujita 5#!and adopted by the NationalWeather Service, as shown in Table 1. EF-Scale winds are defined to apply at a 33-ft10-m
24、! height.Rankine combined vortex: A two-dimensionalcircular flow in which a circular region aboutthe origin is in solid rotation:VtrRH11005 constant , 1!where:Vtris the tangential tornado wind speed;R is the radial distance from the origin; theregion outside is free of vortex motion,the speed being
25、inversely proportional tothe radial distance from the origin:VtrR H11005 constant . 2!vortex: A vortex is any closed circulation flow.wind-generated missile: Wind-generated mis-siles are objects that either become airborne ortumble along the ground or both, as the resultof the wind pressure forces a
26、nd the aerody-namic characteristics of the objects.3 Characterization of rare andextreme wind eventsTornado and hurricane winds are typically char-acterized as rare events while thunderstorm orother straight line winds are characterized asextreme events. In general, the probability den-sity function
27、s describing extreme and rareevents are different 6#.3.1 Regionalization of wind speedsMeteorological and topographic conditions, whichvary significantly within the continental UnitedStates, influence the frequency of occurrence andvelocity of rare and extreme winds6#. Geograph-ical wind speed regio
28、ns for extreme and rareevents for the continental United States areshown in Fig. 1. These regions are correlated withwind speeds as shown in Figs. 2, 3, and 4 andTable 2 for return periods between 101and 107years and frequency of occurrence of 10H1100210yearto 10H1100270year. The tornado wind speeds
29、 presentedin Figs. 2, 3, and 4 are based on the EF Scale,which correlates damage to wind.3.2 Rare events3.2.1 TornadoesTornadoes can be characterized as a mutuallyconsistent set of parameters including maxi-mum total wind speed; radius of maximum tan-gential wind speed; tangential, vertical, radial,
30、and translational wind speeds of the tornado;and associated atmospheric pressure changeswithin the tornado wind field.Using historical data, the mean tornado widthis 233 ft75 m!. The tornado width is defined asthe tornado diameter corresponding to 75 mph34 m0s!. The tornado path is seldom more than1
31、0 miles 16 km! long, although extreme caseshave been recorded where the path of the stormextended more than 200 miles 320 km!7#.The parameters used in this standard to estab-lish engineering tornado models are thefollowing:V is the specified tornado maximum windspeed;Vtris the specified tornado maxi
32、mium rota-tion or tangential wind speed;Vtis the vortex translational speed VtH113505 mph H113502.2 m0s!;Table 1 Recommended EF-Scalewind speed rangesRecommended EF ScaleEF classes3-second-gust wind speed(mph)EF0 65 to 85EF1 86 to 110EF2 111 to 135EF3 136 to 165EF4 166 to 200EF5 .200American Nationa
33、l Standard ANSI0ANS-2.3-20112R is the radius of tangential wind speed;Rmis the radius of maximum tangential windspeed;H9004p is the maximum atmospheric pressuredrop;r is the air density.The tangential Vtr!, radial Vr!, and verticalVz! wind fields vary with height and radiusbut may be assumed constan
34、t with height fordesign purposes. The maximum radial windspeed is assumed to be 0.7 times the maximumtangential wind. The height of the radial in-flow layer shall be at least 0.35 R. Above thisheight, the radial wind is assumed to be zero orto flow outward. The vertical wind field is as-sumed to be
35、mass consistent with the radialwind field.The maximum radial wind and the height of theradial inflow layer are prescribed based on theo-retical work. Numerical and analytical modelswere evaluated and compared with known phys-ical principals and observational data. The mostrepresentative numerical mo
36、dels8#,9#and an-alytical models 10# agree concerning the loca-tion and magnitude of these two parameters.The minimum vortex translational speed is de-finedtobe.5 mph 2.2 m0s!. The atmosphericpressure drop shall be determined by integrat-ing the cyclostrophic equation using a Rankinecombined vortex.T
37、he maximum tangential wind speed shall bedefined asVtrH11005 VH11002Vt. 3!Figure 1 Regionalization of extreme and rare wind eventsAmerican National Standard ANSI0ANS-2.3-20113The rate of pressure change is given byH9004rH11005rVtr2. 4!Design basis tornado wind field characteristicscorresponding to v
38、arious wind speeds are tab-ulated in Table 2. These were arrived at byconsensus based on the work by Abbey 11#.More current tornado hazard probability mod-els and data have been developed and analyzedand form the basis for the recommended max-imum tornado wind speeds in this standard12#. These wind
39、speeds incorporated the EFdamage to wind speeds relationship results andare presented in Table 1 and in Figs. 2, 3, and4 for tornado wind speeds as a function of meanannual frequency of occurrence for the threeregions of the continental United States shownin Fig. 1.3.2.2 HurricanesHurricanes are als
40、o cyclonic in nature andcan be characterized in much the same man-ner as tornadoes except that the path widthand length of the storm are typically 50 to100 times those of a tornado. The maximum3-second-gust wind speeds seldom exceed 200mph 90 m0s!. In most areas tornado windvelocites will envelop hu
41、rricane wind veloc-ites, but hurricane missile velocities as a func-tion of wind speed will exceed tornado missilevelocities. Tornadoes often occur in the rightfront quadrant of hurricanes, the region ofmaximum convection, when they make landfall.Hurricane characteristics are much the sameas for str
42、aight line wind effects in that they donot include a pressure drop component. Windspeeds for hurricanes are as shown in Fig. 3,which are based on data given in Table 3. Thesehurricane wind speeds are consistent with thosegiven in Ref. 13.Maximum hurricane wind speeds Vh! in Re-gion II are divided in
43、to two zones relative totheir proximity to the Atlantic and Gulf of Mex-ico coasts. H1 defines hurricane wind speed asFigure2Windspeeds at a Region I wind hazard siteAmerican National Standard ANSI0ANS-2.3-20114Figure3Windspeeds at a Region II wind hazard siteTable 2 Design basis tornado wind field
44、characteristicsMaximum tornadowind speedVTranslationalwind speedTRadiusRmMaximum atmosphericpressure dropDP1!250 mph 112 msH110021! 55 mph 24 msH110021! 435 ft 133 m! 1.35 psi 9.1 kPa!200 mph 89 msH110021! 45 mph 20 msH110021! 355 ft 108 m! 0.85 psi 5.8 kPa!180 mph 80 msH110021! 40 mph 18 msH110021!
45、 320 ft 98 m! 0.70 psi 4.8 kPa!150 mph 67 msH110021! 33 mph 16 msH110021! 270 ft 82 m! 0.49 psi 3.3 kPa!140 mph 63 msH110021! 32 mph 14 msH110021! 253 ft 77 m! 0.41 psi 2.8 kPa!100 mph 45 msH110021! 25 mph 11 msH110021! 185 ft 56 m! 0.20 psi 1.4 kPa!1!dH9004P H11005rVtr2H11005 3.546 H11003 10H110025
46、Vtr2where Vtris in miles per hour mph!#,where:H9004P H11005 psi kilopascal kPa!#;rH11005 3.546 H11003 1055density constant to convert wind velocity in mph to pressure in psi;VtrH11005 maximum rotational or tangetial wind speed H11005V H11002 T!;1.0 psi H11005 6.8 kPa.American National Standard ANSI0
47、ANS-2.3-20115a function of frequency of occurrence and meanreturn periods within 30 miles 48 km! of thecoast while H2 defines the hurricane windspeeds in the zone .30 miles 50 km! and ,60miles 100 km! of the coast.3.3 Extreme straight line wind eventsFor the three regions of the continental UnitedSt
48、ates, the recommended 3-second-gust windspeeds as a function of the mean return periodare presented in Table 2 and in Figs. 2, 3, and4 14#. These tables and figures for straightand hurricane wind speeds are an extension ofTable C6-7 in “Commentary,” ASCE0SEI 7-05,“Minimum Design Loads for Buildings
49、andOther Structures” 14#.3.4 Localization of wind speedsFor a facility at a particular site, to be de-signed for a given return period or frequencyof exceedence, the regional maximum windspeeds recommended in Secs. 3.1, 3.2, and 3.3should be used. Alternatively, where special windregions are indicated, site-specific studies thataccount for local topographical and meteorolog-ical site characterstics, as outlined here, maybe used.A probability tornado wind hazard model forthe continental United States and computa-tion
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