Design Wind Pressures: Enclosed and Partially Enclosed Rigid Buildings
Calculation of design wind pressures is given in Section 27.4-1 and it is calculated as follows:
| p = q G Cp - qi(GCpi) | (27.4-1) |
However, it is assumed that internal pressures cancel each other for the main resisting systems so that the above equation is simplified to
| p = q G Cp |
in which
| q = 0.00256 KzKztKdV2 | (27.3-1) |
and
Kz: Velocity pressure exposure coefficient (Section 27.3.1). It is determined based on exposure type and height above ground (see Table 27.3-1). Exposure Type is entered by the user.
Kzt: Topographic factor (Section 36.8.2). It can be specified by the user or it is calculated from
| Kzt = (1+K1K2K3)2 | (26.8-1) |
in which K1, K2 and γ for K3 are entered by the user . If only Kzt is entered, this value is applied for all heights. Otherwise, its variation with height is considered as given in Section 26.8-1.
Kd: Wind directionality factor (Section 26.6). It is taken as 0.85 if specified by the user.
V: Basic wind speed (Section 26.5).
G: Gust factor calculated according to Section 26.9-6. It can be taken as 0.85 if specified by the user.
Cp: External pressure coefficients (Figure 27.4-1). A value of 0.8 is used for Windward wall and an interpolated value is used for Leeward wall if needed.