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RE: 1970's Panelized Roof - Question

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Roger,
Thank you and I mean it sincerely. I never would have gotten this far
toward finding these helpful values without your help and advice. It
helps me a great deal to put this project in better perspective.
The contractor faxed me a revised framing plan that he did of the area.
He finally crawled up into the space (claimed he did not have the
ladders and equipment to get up into the space between the T-Bar and
roof to verify the width, depth and spacing of the structural members.
He crawled into the area above the mezzanine adjacent to where the A/C
units are to go and faxed me a revised plan with more accurate spacing.
With the information you provided, I can go back to the sub-purlins and
work outward to obtain more accurate deflection and stress calcs.
He claims that there were no stamps on any of the GLB's that he studied.

I'll run the numbers later today to see what happens.

Thanks again for all your help.

Dennis

Dennis S. Wish, PE
California Professional Engineer
The Structuralist.Net Information Infrastructure

Website:
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-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
Sent: Thursday, February 14, 2002 7:57 AM
To: SEAOC Listservice
Subject: 1970's Panelized Roof - Question

Dennis,

Based on the GLB sizes in your original post, here are the properties
**per
inch of width** for GLBs composed of 1-5/8" laminations:

Depth Should be   A(in^2)  S(in^3)  I(in^4)  Vol. (ft^3)

24" -> 24-3/8"    24.38    99.02    1207     .169

26" -> 26"        26.0     112.7    1465     .181

HTH

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

Dennis Wish wrote:

. > I have client who is adding 10 A/C units to the top of an existing
. > building constructed in the 70's. The roof is a panelized roof:
. > 2x4 @ 16" o.c. DF #1 Sub-Purlins - 8'-0" maximum span
. > 4x16 @ 8' o.c. DF #1 Purlins - 18'-9" maximum span
. > 6x24" DF/DF GLB (exact size not yet verified) Beam at 18'-8" apart
up to
. > 47'-6" span.
. > 7x26" DF/DF GLB (exact size not yet verified) Girders at 45' Average
. > spacing and 37'-6" maximum span

. > The problem is that I can't get the GLB's to work based on a 12-PSF
dead
. > load and reducible 20-psf live load (16-psf on the Beam and 12-psf
on
. > the Girder). I still have to add the A/C units to the Girders.

. > What have others done to calc out an old roof for additional
mechanical
. > loads on an older Masonry bldg w/ panelized roof? The building was
. > originally a Thrifty Drug Store and is being remodeled into two
stores?

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