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Design velocity pressure for ASD and LRFD are: <br />ASD: q,10 ASD = (0.6)(q, .to) (Eq. 5) <br />LRFD: q7,O(1.0)(q7 <br />_LRFD 1o) (Eq.6) <br />where: <br />0.6 11SCE, 7-10 ASD load factor for wind <br />1.0 = ASCE 7-10 LRFD load factor for wind <br />Values for the topographic factor are taken as 1.0 and the wind directionality factor is taken as <br />0.85. ASCE 7-10 and ASCE 7-05 equations for calculation of design velocity pressure have a <br />similar form and are easily compared. For example, the importance factor applicable in ASCE 7- <br />05 calculations is not a specific factor in the ASCE 7-10 calculation (i.e. building or structure <br />importance is addressed by use of separate wind speed maps that vary by risk category in ASCE <br />7-10); and load factors for calculation of ASD and LRFD design wind pressures are different. <br />The effects of these changes on design velocity pressure, when combined with changes to the <br />mapped basic wind speed, are less obvious. To see effects, equations I through 6 are applied to <br />buildings of different risk categories in different U.S. locations. <br />Risk Category and BuiNing Location <br />Design velocity pressures for specific building locations and risk categories are shown in Table <br />1. All locations are within the hurricane prone region with the exception of Dallas, TX. Wind <br />speeds shown for each location within the hurricane prone region are taken from ASCE 7 <br />Counnenteny Tables C26.5-3. From Table 1, it can be seen that for a given location under ASCE <br />7-10, mapped velocity varies by risk category. For example, in Miami, FL, Risk Category 11 has <br />a design wind speed of 170 mph while Risk Categories fit and IV have a design wind speed of <br />180 mph. <br />Use of the term "risk category" and descriptions of varying risk categories in ASCE 7-10 is new. <br />For purposes of comparison in this paper, risk categories in ASCE 7-10, are analogous to the <br />familiar occupancy categories in ASCE 7-05. For example, Risk Category 11 can be associated <br />with most residential dwellings and other buildings and structures with limited occupancies (e.g. <br />those that are not Risk Category 1, 111, or IV). Risk Category III is associated with building types <br />that pose Substantial risk to human life and Risk Category IV is associated with buildings that are <br />designated as essential facilities. <br />ASCE 7-10 Wind Provisions 3 LinelCoulbourne <br />