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RE: Beam unbraced length

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Gunnar Isleifsson wrote:

. > a picture is worth a thousand words

which leaves me speechless <G>.

Sloping glass in aircraft control towers is common, but I don't know if the 
panes commonly used are of comparable size.  Have you contacted glass 
companies to see how they have handled this in other situations?

I noticed that there is a horizontal mullion.  Has it been suggested to the 
architect that separate window blinds be used in different parts of the 
window to give the controllers maximum flexibility in controlling 
glare/sunlight?

There are a couple of "inverted pyramid" buildings in Arizona that have the 
outside surface sloping at 45 deg.  The first one that I was aware of was the 
Tempe (Arizona) City Hall, designed by the architectural firm, Michael and 
Kemper Goodwin and built in the late 1960's, early 1970's.  The intent, IIRC, 
was to reduce cooling costs by limiting the time windows are exposed to 
direct sunlight.  A copycat building was built here in Tucson several years 
later and it seems that the windows are magnets for rocks and/or bullets.  Of 
course, in these buildings, minimizing obstructions was not a primary 
concern.  The City of Tucson keeps microfiche copies of plans indefinitely 
and are public records; the City of Tempe, IIRC, keeps plans only 24 months.

A. Roger Turk, P.E.(Structural)
Tucson, Arizona

Gunnar H. Isleifsson wrote:

. > The "beams" are actually 23 ft. long, 4 in. deep and 3 in. wide, I-formed,
. > inclined window-posts, supporting up to 13 ft. long and 7 ft. wide glass
. > panes. The individual glass panes are supported at the bottom side on
. > horizontal T-formed sections, that also act as bracing for the posts. The
. > bracing can only be connected to the outer flange, since blinds 
. > (sun-screens?) shall run in between the flanges (new problem). The posts 
. > are fixed at the bottom and have a vertical gliding connection at the top 
. > to the roof beams, so as not to transfer any compressive loads from the 
. > roof into the posts. It is imperative that the posts and bracing be as 
. > small as possible to minimize blind spots. My problem is the 13 ft. long 
. > laterally unbraced span. I can make a fixed connection between the posts 
. > and the bracing, but the bracing has a very limited flexural stiffness. 
. > If you have a Flash plug-in in your browser you can see some 
. > computer-generated pictures of the structure at the architects website
. > http://www.vlark.dk . The website is in Danish, but, as they say, a 
. > picture is worth a thousand words.

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