Design Wind Load Cases

Load cases for buildings with any heights are created according to design wind load cases given in Figure 27.4-8. The figure contains four cases but they are expanded to 12 cases when both X-axis and Y-axis are selected. If only X-axis or only Y-axis is selected, only the corresponding directions of Case 1 and Case 2 are created.

It should be noted that eccentricities for X and Y directions are defined respectively with ±0.15 B_x and ±0.15 B_y for rigid buildings, where B is the building dimension perpendicular to the wind direction. If the building is flexible in that direction, eccentricities are calculated with respect to the following equation:

e = \frac{e_{Q} + 1.7 I_{z} \sqrt{{(g_{Q} Q e_{Q})}^{2} + {(g_{R} R e_{R})}^{2}}}{1 + 1.7 I_{z} \sqrt{{(g_{Q} Q)}^{2} + {(g_{R} R)}^{2}}}

(27.4-5)

where

e_R

taken as the distance between center of rigidity and center of mass of each floor

The program automatically creates a load case for calculation of center of rigidity if it is a flexible building. The eccentrically applied loads in both directions are shown in Generated wind load cases for Case 4 . These load cases correspond to Case 4 in Figure 27.4-8.