Establish the wind pressures on the building in Problem P2.13 when the windward roof is subjected to

Question:

Establish the wind pressures on the building in Problem P2.13 when the windward roof is subjected to an uplift wind force.

Problem P2.13

The dimensions of an enclosed gabled building are shown in Figure P2.13a. The external pressures for the wind load perpendicular to the ridge of the building are shown in Figure P2.13b. Note that the wind pressure can act toward or away from the windward roof surface. For the particular building dimensions given, the $C_{p}$ value for the roof based on the ASCE standard can be determined from Table P2.13, where plus and minus signs signify pressures acting toward and away from the surfaces, respectively. Where two values of $C_{p}$ are listed, this indicates that the windward roof slope is subjected to either positive or negative pressures, and the roof structure should be designed for both loading conditions. The ASCE standard permits linear interpolation for the value of the inclined angle of roof $θ$ . But interpolation should only be carried out between values of the same sign. Establish the wind pressures on the building when positive pressure acts on the windward roof. Use the following data: basic wind speed $= 100 m i / h$ , wind exposure category $= B$ , $K_{d} = 0.85, K_{z t} = 1.0, G = 0.85$ , and $C_{p} = 0.8$ for windward wall and -0.2 for leeward wall.