Field-measured atmospheric boundary layer characteristics in high winds

While limited data have been collected on the wind effects on low-rise construction, few have been in high winds. Not only is there a general lack of structural load and resistance data in these storms, but also there is a paucity of detailed meteorological data. Although the most recent revision of the wind load provisions of the ASCE Standard (ASCE 7-98) includes updated information for use in hurricane-prone regions, questions still remain about the suitability of these provisions in high-wind regions. An ongoing full-scale field measurement program begun in 1997, in Southern Shores, North Carolina offers an opportunity to collect and analyze data in hurricanes and other high wind events and contribute to some of the existing data gaps in this area. To date the system has collected measurements of the wind environment, pressure loading and structural resistance during the passage of frontal systems, in several northeasters, arid during three hurricanes making landfall in North Carolina (Hurricane Bonnie (1998) and Hurricanes Dennis and Floyd (1999)). One of the main goals of this measurement program is to compare the loads measured during these high wind events to the loads predicted by the ASCE standard in similar meteorological conditions. An additional goal is to compare properties of winds from different storm types (e.g., hurricanes, tropical storms, northeasters, thunderstorms) and to compare measurements with various widely accepted models (e.g., Durst relationship for time averaging effects, spectral content). The main goal of this paper is to present summary results from the meteorological data collected in the three hurricanes. In addition, analyses of the gust structure (including turbulence intensity and effects of averaging time on reported gusts) and a preliminary attempt to quantitatively describe the surrounding terrain will be presented.