Analysis of gust winds in the United States has resulted in a new wind speed map for design-level winds. The map is based on 50-year peak gust speeds rather than fastest mile speeds used in the national wind load standard ANSI/ASCE 7-93. The change in gust duration is necessary because the fastest mile wind record has ended. A new technique was used to reduce variability due to sampling error in non-hurricane areas. Individual stations were demonstrated to be statistically independent and were combined as regional superstations. The purpose was to decrease sampling error by effectively increasing sample length. Wind speeds on the hurricane coast were converted from fastest mile to peak gust using new information on gusts in hurricanes. In addition, three Monte Carlo studies of hurricane speeds were considered in place of the one study available for the earlier map. Wind speeds for various return periods are presented.

Closure of "Design Gust Wind Speeds in the United States"

Reference wind velocity pressures corresponding to specified return period wind speeds are provided in several Canadian design codes. A review of the two most recent editions of the National Buildi...

Basis for recommending an update of wind velocity pressures in Canadian design codes

Projections of Future US Design Wind Speeds Due to Climate Change for Estimating Hurricane Losses

The small sample size of the annual maximum wind speed at a wind speed recording site causes uncertainty in the estimated return period of wind speed. The influence of this uncertainty on the estimated return period values of annual maximum wind speed and structural reliability is quantified in this study. The results show that the effect of statistical uncertainty due to limited sample size on the estimated return period value of the wind speed and structural reliability is largely reduced if the sample size is increased from 10 to 20. The implication of the results is discussed in terms of two alternative options to specify the factored design wind load: (i) a low return period for selecting nominal wind speed combined with a large wind load factor and (ii) a high return period for selecting nominal wind speed combined with unity wind load factor. It was concluded that option (i) is preferred to cope with sample size effect if the design in a region with statistically homogeneous wind climate; for code ...

Sample size effect on the reliability and calibration of design wind load

Calibration of the design wind load and snow load considering the historical climate statistics and climate change effects

ASCE 7-10 Minimum Design Loads for Buildings and Other Structures contains several changes regarding wind loads. The major editorial change is a complete reorganization to a multiple-chapter format as done previously for seismic loads with the objective being to make the provisions easier to follow. Technical changes include the introduction of new wind speed maps to be used with a 1.0 load factor for LRFD and a 0.6 load factor for ASD, the reintroduction of Exposure D for water surfaces in hurricane-prone regions, and revised wind-borne debris regions. A new simplified procedure for buildings up to 160 ft has been added based on the provisions for buildings of all heights.

Ronald Cook

Papers

ASCE 7-10 Wind Loads