Revisiting Gust Averaging Time and Gust Effect Factor in ASCE 7
Publication: Journal of Structural Engineering
Volume 140, Issue 11
Abstract
A peak gust–based wind map was first introduced in ASCE 7-95 to replace the fastest mile wind speed used in earlier versions of the ASCE 7 standard based on wind records using the National Weather Service (NWS) F420C cup anemometer/chart recording system. The peak gust in ASCE 7-95 was considered to be of 2–3 s duration and was referred to as a 3-s gust in the standard. This may imply that an instantaneous gust speed is recorded during the referenced time period, and thus it is not equivalent to the commonly used moving average time. The formulation of the gust-effect factor in ASCE 7 has implicitly utilized a 3-s moving average assumption, which may introduce an inconsistency in gust averaging time between the basic wind speed and the gust-effect factor. This calls for a careful examination in this context of the relationship between gust duration and moving average time to seek consistency and transparency in the formulation of the ASCE 7 standard. In an effort to clarify the gust averaging time, this study firstly investigates the response characteristics of the NWS F420C anemometer/recording system and then identifies an equivalent moving average time. Since the gust effect factor formulation is closely related to the gust averaging time, which is also tied to the gust velocity factor associated with the relationship between the peak and mean wind velocities, the formulation is revisited to evaluate the effect of average time. A modified gust effect factor corresponding to the established equivalent moving average time is established. In addition, the potential impact on the wind profile corresponding to the equivalent averaging time is discussed. Finally, the effects of the gust averaging time on the alongwind response of tall buildings are examined from survivability and serviceability design perspectives.
Get full access to this article
View all available purchase options and get full access to this article.
Acknowledgments
The authors are grateful for the financial support provided in part by a collaborative research project between the NatHaz Modeling Laboratory and the Global Center of Excellence (GCOE) at Tokyo Polytechnic University funded by MEXT, Japan, and NSF Grant CMMI 1301008. Special thanks go to Dr. Enrica Bernardini of the NatHaz Modeling Laboratory for her comments on the manuscript.
References
ASCE. (1995). “Minimum design loads for buildings and other structures.”, Reston, VA.
Beljaars, A. C. M. (1987). “The influence of sampling and filtering on measured wind gusts.” J. Atmos. Oceanic Technol., 4(4), 613–626.
Davenport, A. G. (1964). “Note on the distribution of the largest value of a random function with application to gust loading.” Proc. Inst. Civ. Eng., 28(2), 187–196.
Durst, C. S. (1960). “Wind speeds over short periods of time.” Meteorol. Mag., 89(1056), 181–186.
Engineering Sciences Data Unit (ESDU). (2002). “Strong winds in the atmospheric boundary layer—Part 2: Discrete gust speeds.” ESDU International plc, London, U.K.
Gurley, K., and Kareem, A. (1993). “Gust loading factors for tension leg platforms.” Appl. Ocean Res., 15(3), 137–154.
Holmes, J. D., and Allsop, A. (2012). “Averaging times and gust durations for codes and standards.” Proc., 10th U.K. Conf. on Wind Engineering (WES-2012), Wind Engineering Society, U.K., 207–210.
Holmes, J. D., and Ginger, J. D. (2012). “The gust wind speed duration in AS/NZS 1170.2.” Aust. J. Struct. Eng., 13(3), 207–218.
International Association of Wind Engineering (IAWE). (2008). “Benchmark buildings for an international HFBB comparison.” 〈http://www.iawe.org/committes.html〉 (Jun. 26, 2013).
Kwon, D. K., and Kareem, A. (2014). “Revisiting gust averaging time and gust effect factor in ASCE 7.”, Univ. of Notre Dame.
Lockhart, T. J. (1996a). “Wind averaging: The 5-second vs. 3-second question.”, Dept. of Atmospheric Science, Colorado State Univ.
Lockhart, T. J. (1996b). “Gust recorder response tests.”, Dept. of Atmospheric Science, Colorado State Univ.
Lombardo, F. T. (2012). “Improved extreme wind speed estimation for wind engineering applications.” J. Wind Eng. Ind. Aerodyn., 104–106, 278–284.
Lombardo, F. T., Main, J. A., and Simiu, E. (2009). “Automated extraction and classification of thunderstorm and non-thunderstorm wind data for extreme-value analysis.” J. Wind Eng. Ind. Aerodyn., 97(3–4), 120–131.
Masters, F. J., Vickery, P. J., Bacon, P., and Rappaport, E. N. (2010). “Toward objective, standardized intensity estimates from surface wind speed observations.” Bull. Am. Meteorol. Soc., 91(12), 1665–1681.
McKee, T. B., Doesken, N. J., and Kleist, J. (1996). “Climate data continuity with ASOS—report for the period September 1994–March 1996.”, Dept. of Atmospheric Science, Colorado State Univ.
Miller, C. (2007). “Defining the effective duration of a gust.” Proc., 12th Int. Conf. on Wind Engineering, Australasian Wind Engineering Society, Australia, 759–766.
National Institute of Standards and Technology (NIST). (2012). “Standardized extreme wind speed database for the United States.” 〈http://www.itl.nist.gov/div898/winds/NIST_TN/nist_tn.htm〉 (May 25, 2013).
National Oceanic and Atmospheric Administration (NOAA). (1998). Automated Surface Observing System (ASOS), User’s guide.
National Research Council (NRC). (2011). The National Weather Service modernization and associated restructuring—a retrospective assessment, National Research Council of the National Academies, The National Academies Press, Ottawa, Canada.
National Severe Storms Laboratory (NSSL). (1971). The NSSL surface network and observations of hazardous wind gusts, NOAA Technical Memorandum ERL NSSL-55, National Oceanic and Atmospheric Administration (NOAA), U.S. Dept. of Commerce (DOC), Norman, OK.
Peterka, J. A., and Shahid, S. (1998). “Design gust wind speeds in the United States.” J. Struct. Eng., 207–214.
Simiu, E., Wilcox, R., Sadek, F., and Filliben, J. J. (2003). “Wind speeds in ASCE 7 standard peak-gust map: Assessment.” J. Struct. Eng., 427–439.
Solari, G. (1993a). “Gust buffeting. I: Peak wind velocity and equivalent pressure.” J. Struct. Eng., 365–382.
Solari, G. (1993b). “Gust buffeting. II: Dynamic along-wind response.” J. Struct. Eng., 383–397.
Solari, G., and Kareem, A. (1998). “On the formulation of ASCE 7-95 gust effect factor.” J. Wind Eng. Ind. Aerodyn., 77–78, 673–684.
Sparks, W. (1997). “The gust response of Mk IV wind systems.”, U.K. Met Office., Exeter, U.K.
Verkaik, J. W. (2000). “Evaluation of two gustiness models for exposure correction calculations.” J. Appl. Meteorol., 39(9), 1613–1626.
Vickery, P. J., and Skerlj, P. F. (2005). “Hurricane gust factors revisited.” J. Struct. Eng., 825–832.
Vickery, P. J., Skerlj, P. F., and Twisdale, L. A., Jr. (2000). “Simulation of hurricane risk in the U.S. using an empirical track model.” J. Struct. Eng., 1222–1237.
Vickery, P. J., Wadhera, D., Twisdale, L. A., Jr., and Lavelle, F. M. (2009). “United States hurricane wind speed risk and uncertainty.” J. Struct. Eng., 301–320.
Wieringa, J. (1976). “An objective exposure correction method for average wind speeds measured at a sheltered location.” Q. J. R. Meteorol. Soc., 102(431), 241–253.
World Meteorological Organization (WMO). (2008). “Guide to meteorological instruments and methods of observation.” Geneva, Switzerland.
Zhou, Y., and Kareem, A. (2002). “Definition of wind profiles in ASCE 7.” J. Struct. Eng., 1082–1086.
Information & Authors
Information
Published In
Copyright
© 2014 American Society of Civil Engineers.
History
Received: Oct 28, 2013
Accepted: Apr 17, 2014
Published online: May 22, 2014
Discussion open until: Oct 22, 2014
Published in print: Nov 1, 2014
Authors
Metrics & Citations
Metrics
Citations
Download citation
If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download.