ASCE 7-10 WIND LOADS-2013 Wind Loads Guide to the Wind Load Provisions of ASCE 7-10.pdf

1、 Wind Loads9780784412756.fm.indd i 4/12/13 11:19 PMOther Titles of InterestMinimum Design Loads for Buildings and Other Structures, ASCE/SEI 7-10. (ASCE Standard, 2010). Provides requirements for general structural design and includes means for determining various load and their combina-tions. Inclu

2、des commentary. (ISBN 9780784410851)Signifi cant Changes to the Wind Load Provisions of ASCE 7-10: An Illus-trated Guide, by T. Eric Stafford. (ASCE Press, 2011). Summarizes changes to the wind load requirements set forth in Standard ASCE/SEI 7-10. (ISBN 9780784411162)Signifi cant Changes to the Sei

3、smic Load Provisions of ASCE 7-10: An Illustrated Guide, by S. K. Ghosh, Susan Dowty, and Prabuddha Dasgupta. (ASCE Press, 2011). Describes the revisions to the seismic requirements set forth in Standard ASCE/SEI 7-10. (ISBN 9780784411179)Snow Loads: Guide to the Snow Load Provisions of ASCE 7-10, b

4、y Michael ORourke. (ASCE Press, 2010). Presents a detailed, authoritative interpreta-tion of the snow load provisions of ASCE/SEI 7-10, including worked exam-ples and FAQs. (ISBN 9780784411117)Urban Aerodynamics: Wind Engineering for Urban Planners and Design-ers, by the Task Committee on Urban Aero

5、dynamics. (Technical Report, 2011). Introduces the basic tools and technology used by engineers to deter-mine the effects of wind on city streets and structures. (ISBN 9780784411797)Wind Issues in the Design of Buildings, by Leighton Cochram. (Technical Report, 2012). Explains the ways that structur

6、al designers accommodate the effect of extreme wind events on the built environment. (ISBN 9780784412251)Wind Loads for Petrochemical and Other Industrial Facilities, by Task Committee on Wind-Induced Forces of the Petrochemical Committee of the Energy Division. (Technical Report, 2011). Provides st

7、ate-of-the-practice guidelines for the computation of wind-induced forces on industrial facilities with structural features outside the scope of current codes and standards. (ISBN 9780784411803)9780784412756.fm.indd ii 4/12/13 11:19 PMWind LoadsGuide to the Wind Load Provisions of ASCE 7-10Kishor C.

8、 Mehta, Ph.D., P.E.William L. Coulbourne, P.E.9780784412756.fm.indd iii 4/12/13 11:19 PMLibrary of Congress Cataloging-in-Publication DataMehta, Kishor C.Wind loads : guide to the wind load provisions of ASCE 7-10 / Kishor C. Mehta, Ph.D., P.E., William L. Coulbourne, P.E.pages cmRevision of: Wind l

9、oads : guide to the wind load provisions of ASCE 7-05 / Kishor C. Mehta, William L. Coulbourne, copyrighted in 2010.Includes bibliographical references and index.ISBN 978-0-7844-1275-6 (pbk.) ISBN 978-0-7844-7778-6 (e-book)1. Wind-pressure. 2. Wind resistant design. 3. BuildingsStandardsUnited State

10、s. 4. BuildingsAerodynamics. 5. Gust loads. I. Coulbourne, William L. II. American Society of Civil Engineers. III. Title.TH891.M454 2013690.21dc232013000236Published by American Society of Civil Engineers1801 Alexander Bell DriveReston, Virginia 20191www.asce.org/pubsAny statements expressed in the

11、se materials are those of the individual authors and do not necessarily represent the views of ASCE, which takes no responsibility for any statement made herein. No reference made in this publication to any specifi c method, product, process, or service constitutes or implies an endorsement, recom-m

12、endation, or warranty thereof by ASCE. The materials are for general information only and do not represent a standard of ASCE, nor are they intended as a reference in purchase specifi cations, contracts, regulations, statutes, or any other legal document.ASCE makes no representation or warranty of a

13、ny kind, whether express or implied, concerning the accuracy, completeness, suitability, or utility of any information, apparatus, product, or process discussed in this publication, and assumes no liabil-ity therefor. This information should not be used without fi rst securing competent advice with

14、respect to its suitability for any general or specifi c application. Anyone utilizing this information assumes all liability arising from such use, including but not limited to infringement of any patent or patents.ASCE and American Society of Civil EngineersRegistered in U.S. Patent and Trademark O

15、ffi ce.Photocopies and permissions. Permission to photocopy or reproduce material from ASCE publications can be obtained by sending an e-mail to permissionsasce.org or by locating a title in ASCEs online database (http:/cedb.asce.org) and using the “Permission to Reuse” link. Copyright 2013 by the A

16、merican Society of Civil Engineers.All Rights Reserved.ISBN 978-0-7844-1275-6 (paper)ISBN 978-0-7844-7778-6 (e-book)ISBN 978-0-7844-7779-3 (e-book)Manufactured in the United States of America.19 18 17 16 15 14 13 1 2 3 4 59780784412756.fm.indd iv 4/12/13 11:19 PMWind Loads: Guide to the Wind Load Pr

17、ovisions of ASCE 7-10 v v ContentsPreface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viiUnit Conversions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viiiGeneral Requirements1. Introduction . . . . . .

18、 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Objective of the Guide. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21.2 Signifi cant Changes and Additions. . . . . . . . . . . . . . . . . . . . . . 21.3 Limitations of the Standard . . . . . . . . . . .

19、 . . . . . . . . . . . . . . . . 41.4 Technical Literature. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62. Wind Load Provisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.1 Format . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

20、 . . . . . . . . 92.2 Velocity Pressure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92.3 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102.4 Simplifi ed Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122.5 Wind T

21、unnel Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 152.6 Equations for Graphs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 153. Wind Speeds and Related Risks. . . . . . . . . . . . . . . . . . . . . . . . . . . . 233.1 Wind Speed Maps . . . . . . . . . . . . . .

22、 . . . . . . . . . . . . . . . . . . . 233.2 Load Factors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 253.3 Wind Risks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25Examples4. 160-ft-Tall Offi ce Building. . . . . . . . . . . . . . . . .

23、 . . . . . . . . . . . . . . 274.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 294.2 Building Located on an Escarpment. . . . . . . . . . . . . . . . . . . . 394.3 Simplifi ed Method for Buildings Less Than 160 ft Tall . . . . . 415. Commercial/Warehouse Metal

24、 Building . . . . . . . . . . . . . . . . . . . . . 515.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535.2 Simplifi ed Method for Low-Rise Building . . . . . . . . . . . . . . . 626. Commercial Building with Concrete Masonry Unit Walls . . . . . . . . 716.1 An

25、alytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 736.2 Simplifi ed Method for Low-Rise Buildings . . . . . . . . . . . . . . 797. Commercial Building with Monoslope Roof and Overhang . . . . . . 837.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . .

26、 . . . . . . . 838. L-Shaped House with Gable/Hip Roof . . . . . . . . . . . . . . . . . . . . . . 978.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 979. U-Shaped Apartment Building. . . . . . . . . . . . . . . . . . . . . . . . . . . . 1079.1 Analytical Proce

27、dure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1079780784412756.fm.indd v 4/12/13 11:19 PMvi Wind Loads: Guide to the Wind Load Provisions of ASCE 7-1010. Open Building with Gable Roof . . . . . . . . . . . . . . . . . . . . . . . . . . 12111. Domed Roof Building . . . . . . . . .

28、 . . . . . . . . . . . . . . . . . . . . . . . . 12911.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12912. Unusually Shaped Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13712.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . .

29、 . . . . . . . . . . 13713. Billboard Sign on Flexible Poles . . . . . . . . . . . . . . . . . . . . . . . . . . 14913.1 Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14914. Frequently Asked Questions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15714.

30、1 Wind Speed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15714.2 Load Factor. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15814.3 Terrain Exposure. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15914.4 MWFRS and C these item

31、s are revised and retained in this updated guide.1.1 Objective of the GuideThe objective of this guide is to provide direction in the use of wind load provisions of ASCE 7-10 (referred to as “the Standard”). The Commentary of ASCE 7-10 (chapters C26 through C31) contains a good background and discus

32、sion of the wind load criteria; that information is not repeated in this document. Chapters 4 through 13 of this guide contain 14 worked examples. Vari-ous examples illustrate different methods of obtaining wind loads given in the Standard. Suffi cient details of calculation of wind loads are provid

33、ed to help the reader properly interpret the wind load provisions of the Standard. Sections of the Standard, as well as the fi gures and tables of the Standard, are cited liberally in the examples. The equation numbers given in the examples are from the Standard to allow users to track steps of the

34、Standard. It is nec-essary to have a copy of ASCE 7-10 to follow the examples and work with this Guide. A copy of ASCE 7-10 can be ordered by calling 1-800-548-ASCE or ordered on-line at http:/www.asce.org/bookstore.1.2 Signifi cant Changes and AdditionsThe wind load provisions of ASCE 7-10 appear c

35、ompletely different from the previous versions of the Standard because of a major change in the format. Wind load provisions contained in one chapter (chapter 6) in previ-ous versions are expanded into chapters 26 through 31. This expansion is designed to make provisions more user-friendly. The prov

36、isions are orga-nized by the type of building or structure under consideration, and equa-tions and tables are repeated to provide all necessary items in one location or chapter.In addition to format, other signifi cant changes include wind speed maps that are related to limit state loads, an additio

37、n of a simplifi ed proce-dure for enclosed buildings with roof height equal to or less than 160 ft, and clarifi cations/modifi cations of exposure categories, debris zones, and mini-mum loads. The basic approach to assessing wind loading has not changed. Major changes in format are listed as follows

38、 by each chapter.9780784412756.001.indd 2 4/12/13 7:31 PMWind Loads: Guide to the Wind Load Provisions of ASCE 7-10 3 Chapter 26 contains general requirements for wind load determina-tion. General requirements for all buildings and structures include wind speed, wind directionality, exposure categor

39、y, topographic effect, gust effect factor, enclosure classifi cation, wind-borne debris regions, internal pressure coeffi cient, symbols, and defi nitions. Decisions regarding these require-ments can be made prior to obtaining wind loads for surfaces of buildings and structures.Chapter 27 contains w

40、ind load criteria for the main wind force-resisting system (MWFRS) of buildings using the directional approach. This approach is the traditional approach used since ANSI A58.1-1972. Wind loads criteria in Part 1 are applicable to enclosed, partially enclosed, or open buildings of any height. Criteri

41、a of Part 1 are necessary if wind loads are to be determined for windward, leeward, and side walls and roof including internal pressures for the MWFRS. Part 2 is a new simplifi ed procedure for buildings with roof height equal to or less than 160 ft; the procedure is restricted to enclosed buildings

42、 with simple diaphragms. Simplifi cation in Part 2 constitutes a tab-ular form of pressure values. There are other restrictions for use of the sim-plifi ed procedure of Part 2; these are shown in Chapter 2 of this guide.Chapter 28 contains wind loads criteria for the MWFRS of low-rise buildings (env

43、elope approach for buildings with roof height h less than or equal to 60 ft). Part 1 of the chapter gives equations for velocity pressures and design pressures for windward, leeward, and side walls and roof of the building. Part 2 is a simplifi ed procedure in which horizontal and vertical design pr

44、essures are given in tabular form.Chapter 29 contains wind loads criteria for the MWFRS of other struc-tures and building appurtenances. Structures include chimneys, signs, walls, towers, and others. Building appurtenances are limited to rooftop equip-ment. Wind loads on parapets and overhangs are r

45、eferred to in appropriate sections in other chapters. This cross referencing of sections where loading criteria can be found is designed to make the standard more user-friendly.Chapter 30 contains wind loads criteria for components and cladding (C basic wind speed will be in accordance with local ju

46、risdictions. Exposure Category D is applicable to water surfaces including hur-ricane prone regions. New simplifi ed procedures to obtain wind loads for MWFRS and C horizontal loads on wall surfaces are increased to 16 psf to make them consistent with strength design. On vertical projection of roof,

47、 horizontal loads are specifi ed as one-half of minimum loads on walls. Wind-borne debris regions are revised to relate to building risk categories. Lower limits of wind loads obtained from wind tunnel procedures are specifi ed in the Standard.The aforementioned changes are refl ected in the example

48、 problems of this guide. A new chapter 3 is added to this guide to explain wind speed maps as they relate to risk categories of buildings and structures and load factors in load combinations.1.3 Limitations of the StandardSuccessful use of the Standard is dependent on knowledge of parameters and fac

49、tors used in the algorithms that defi ne the wind loads for design applica-tions. Limitations of some of the signifi cant parameters are given as follows.Assessment of Wind ClimateThe current edition of the Standard provides a more realistic description of wind speeds than did the previous editions. Perhaps the most serious limi-tations are that design speeds are not referenced to direction, and poten-tial wind speed anomalies are defi ned only in terms of special wind regions. Thes