Determing Opening Wind Pressures

[egc]

Ah, another office debate! This is around determining the design wind pressures required for multi-component windows/doors.

Assume you have a 25 SH unit mulled together with a half-round top unit. Two cases:

1. If the manufacturer supplies a pre-engineered combined unit with a unit rated pressure, should the area used in determing the C&C design pressure be the gross area of the combined unit?

2. If the builder has to assemble the combined unit from 2 pieces, should each piece have its design pressure based on each pieces gross area (meaning two different design pressures as one pieces's area < 10 sft and the other > 10 sft)?

The same question applies to double and triple units. I maintain that unless the manufacturer produces such a unit, that the design pressures should be based on the indiviual areas of the pieces not the gross total opening area.

Comments are appreciated

 

[woodengineer]

I agree with you. Unless the 2 or 3 section unit is manufactured as one piece, I would use the smaller tributary thus giving a higher C&C design pressure.

Jordan

 

[RichardPark]

egc,

My understanding is that your unit is two units whether it is assembled in the factory or in the field. The mullion uniting the units is loaded the same in either case.

In addition the 25 SH should be considerd as two areas since the meeting rails are loaded by both halves of the unit and act as a mullion does.

At least that is the way I do it in South Florida.

Dick