Components and Cladding Pressure - Window effective area

[missstructures]

What is the general practice for determining the effective area (to determine components and cladding loads) for windows and doors:
Without necessarily having the specifications for the windows at the time of the calculation, and not knowing what components (how many mullions, or how the mullions are designed to span in an opening) -
would you take the area of the window,
or the smallest opening dimension as "l" and take (l*l/3) - which could lead to conservative pressures?

It seems to me that taking the area of the window for small windows is probably OK, and I usually take l*l/3 for full height windows (assuming that it would have mullions that span the full height) - but I have a hard time with medium size windows.

I'd like to hear what other practicing engineers do.

 

[FSS]

What kind of windows are you talking about? Usually the nominal sizes on the architectural floor plans.

 

[missstructures]

In general - the overall window sizes are called out in the architectural drawings - but the exact window might not - meaning how the window itself is specified - how the mullions are designed to span, etc.

So for the components and cladding pressure calculations - would you use the overall area of the window or try to figure out which way the window is spanning to determined a span * span/3 effective area.

 

[UcfSE]

I would use the area tributary to each component of the window.

You wouldn't use the entire roof area to design a truss, beam or rafter, afterall.