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Chapter 4:Hazard Analysis—High Wind Storms <br /> caused by tropical cyclones. The transition is for peak gusts around 68 mph and an average <br /> return period of around 30 years,therefore just below hurricane strength. <br /> 160 <br /> 140 Tropical <br /> Cyclone <br /> Events <br /> 120 <br /> c 100 <br /> E <br /> 80 <br /> Y <br /> Non-Tropical <br /> R <br /> Wind Events <br /> a. 60 <br /> 40 <br /> 20 <br /> 0 <br /> 10 100 1000 <br /> Return Period,Years <br /> Figure 4-4. Wind hazard curves for the Hawaiian Islands for Tropical Cyclone and Non-Tropical Winds <br /> There is no objective model that is used solely for the purpose of evaluating economic losses <br /> due to high wind events without regard to tropical cyclone occurrences. The future risk of <br /> such events is projected to be roughly equivalent to the historic losses of past events. <br /> 4.5 Mitigation Strategies <br /> 4.5.1 Previous/Current Efforts <br /> Hawaii design wind pressures have changed over the years in the building code. The <br /> Uniform Building Code (UBC) design windspeed was based on an analysis of Honolulu <br /> weather station data by H.C.S. Thom in 1968 without consideration of hurricane history. The <br /> UBC wind loadings have historically lagged the ASCE 7 standard with respect to hurricane <br /> hazard because almost all the UBC constituent states were not in hurricane regions (except <br /> for Hawaii,which was only recently recognized after Hurricane Iwa and Iniki). <br /> Table 4-1. Design Wind Pressures per UBC/IBC Code Years <br /> Building Code Years Design Wind Pressure at IOM height* <br /> IBC 2003 26 psf <br /> UBC 1991 to 1997 30 psf <br /> UBC 1982 to 1988 26.5 psf <br /> UBC 1958 to 1979 15 psf <br /> 4-6 Hawaii County Multi-Hazard Mitigation Plan <br />