Wind Load on Fabric Canopy

[rocketmenno]

I am looking at a small building that will be used as a press box. The building is 8'x33' and sits on top of a high school football stadium. The top of the stadium is about 20' high. On top of the press box is a fabric canopy to shelter press people while they stand on top of the building. It is basically made of aluminum trusses with fabric of top. The canopy engineer supplied reactions on the supports. The reactions don't look to be very accurate. 8 supports.. 4 along the front and 4 along the back. He has the same moment on all the supports 1000 ft#. There is also a set of stairs that go form the ground up to the press box. It has a fabric caopy as well. The trib area for the supports for this canopy are not the same as the roof canopy but the moment is still 1000 ft#.

If I look at it using ASCE7-05 should I treat it as an open Building? Is therre any special considerations for this type of canopy vs a more traditional Canopy over a gas station?

 

[ishvaaag]

Most surely vendor has selected the loads for the structural designer as a function of the tributary area of the canopy. No proper calculation, just overall experience of what he needs there.

Either one takes what he gives or dismisses it and cares for the calculations. Of course fabric structures, open tent type, or sail, are open structures. Shall have more dynamic effects even than steel canopy open structures, other thing is that the structure behave worse than cantilevered roofs on columns, this would depend on the design.

Ask the provider of the data how he came to the values. Then see if can be bettered for a simpler, less costly, feasible and still sound structure.