Are you familiar with the changes to the wind provisions in ASCE 7-16? If you’ve taken the time to look at the wind maps, you may have noticed some significant changes to the contours and wind speed, but there are other changes that will affect your daily designs within the wind provisions. It is important to not only know what has changed, but why the changes were made.
In November 2018, Don Scott, SE, from PCS Structural Solutions, presented ASCE 7-16 Wind Provisions – Changes Affecting the Design Provisions. Don covered the changes to the new wind speed maps and explained how to determine the design wind speed. He also presented the changes to the roof pressure coefficients, and explained the effects of the new Elevation Factor.
Don was able to provide much insight as to what went into the changes to the wind speed maps and roof pressure coefficients. Since ASCE had not made changes to the non-hurricane wind speeds since 7-95, there was a significant increase in new anemometer locations and data gained from these locations. The new maps now reflect more regional variability in extreme wind climates. Wind speeds in the great plains remain unchanged, but for the rest of the country wind speeds have decreased, most significantly along the west coast. Also, new hurricane models have reduced the hurricane winds along the northeast coast, while the hurricane winds along the southeast coastlines remain unchanged.
Don offered two permitted web based tools that may be used to access wind speed data for various locations in the United States. The first option is the Applied Technology Council’s (ATC) WINDSPEED BY LOCATION website which available free of charge. The second option is ASCE 7 HAZARD TOOL which is available to registered members. This tool provides all design parameters specified by ASCE 7-16 for a given site.
While most of the country will appreciate some wind pressure reductions, there will be more regional variability nationwide than in previous editions of ASCE7 due to the new wind map contours. Overall, the new improvements made to the ASCE 7-16 wind provisions will result in more accurate reflections of the wind speeds being witnessed at various anemometer locations throughout the United States.