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RE: LGSS - Light Gauge Steel Stud question

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I'm resubmitting this to change a few unclear lines below.

Dennis Wish PE

|-----Original Message-----
|From: Dennis S. Wish [mailto:wish(--nospam--at)cwia.com]
|Sent: Sunday, March 15, 1998 1:13 PM
|To: Seaoc@Seaoc. Org
|Subject: LGSS - Light Gauge Steel Stud question
|
|
|--------------------------------------------------------------------------
|Your following message has been delivered to the list
|  seaoc(--nospam--at)seaoc.org at 13:18:38 on 15 Mar 1998.
|--------------------------------------------------------------------------
|
|
|I have been designing a clients steel stud homes when I discovered a
problem
|related to their past developments.
|An engineer that they hired (and recenly completed a book on metal stud
|construction)designed their headers using 20 Gauge 8 and 12" sections.
These
|were WCJ sections where the J represents no cutouts.
|
|The manufactures catalog (Steeler in Washington) clearly shows that the H/t
|ratio for web crippling is exceeded in a 20 gauge 8 and 12" section.
|
|The headers (assuming a maximum loading of 420 plf Roof Dead Load and 336
|PLF Roof Live Load) are constructed as a box beam set flang to flange
rather
|than web to web. The beam is capped with a 20 gauge track top and bottom.
|
|I need to suggest a retrofit for the homes under construction. In these
|cases, only the inside face of header is available since the exterior is
|already covered with either sheathing or foam board insulation.
|
|I had thought of using an expansion wing nut (like the kind used to hang
|something from drywall which fits through the whole and spreads out when
|through the hole.
|Combined with a long threaded rod which would place pressure against the
webs
|on the outside face of wall and through back pressure of the spring/wing
nut against the inside face of the web..
|
|The reasoning is as follows:
|I would think that the webs would buckel inward since they are braced by
the
|exterior finish and interior gypsum wallboard.
|The bolts would brace the web from buckeling inword (or at least minimize
|the potential for this kind of hazzard and be easy to install.
|Finally, the bolts can be placed in the along the centerline of the web
|between the flanges to provide lateral support at mid height and where it
will |have little effect on bending.
|
|The contractor suggested screwing in place an additional layer of 20 gauge
plate to the web on the inside face (adjacent to the interior gypsum) - I'm
not comfortable here, but have a
|feeling for how my bolted idea might be effective.
|
|Any other suggestions?
|
|
|Dennis Wish PE
|
|