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SStud: Need opinions about residential construction and steel stud shearwalls[Subject Prev][Subject Next][Thread Prev][Thread Next]
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- Subject: SStud: Need opinions about residential construction and steel stud shearwalls
- From: "Dennis S. Wish PE" <wish(--nospam--at)cyberg8t.com>
- Date: Sun, 30 Nov 1997 11:13:31 -0800
I have been doing work with an organization that has built over 350 homes in my area out of steel stud construction. They have used plywood shear walls following Professor Serrette's work at Santa Clara University. The work that he has been doing has been followed very closely by APA and it has been published as articles in the newsletter for Light Gauge Steel Engineers Association (www.lgsea.com).
I've joined this organization a few months ago, but have not found sufficient design examples in their literature (newsletter or technical journals) to help me feel comfortable with steel stud framing.
I would be interested in receiving the following design examples from those of you who have been designing steel stud:
1. Built-up headers (deep  boxed channel sections) which would also address web crippling potential.
2. Analysis for single 20 gauge top plate continuous over studs for concentracted truss loads located between studs.
3. I have designed shear transfers through a wood truss roof with solid wood blocking placed above a single 20 ga. plate. I have secured the blocking with #8 screws up through the 20 ga. plate into the bottom of the block. My detail specifies three screws per block with a minimum of 1 1/2" embedment into the block. The diaphragm connection to the truss and blocking is done conventionally with 8d common boundary nails at 4" on center. I do not have a guideline to follow and feel that the shear transfer is adequate by the numbers, however, I would be interested in the opinions of others.
4. How would you create a drag connection from a truss located parallal and above a metal stud wall when the truss is wood. I have done this by a connection of a conventional Simpson strap nailed to the bottom of the truss and screwed with self-tapping screws to the steel top plate of the wall. The framing above the wall is generally perpendicular to the wall and continuously blocked. This avoids failure of the connection in compression and seems to satisfy the drag condition in tension. Any opinions?
5. The APA recommendation for shearwall values using plywood or OSB against metal studs requires the use of 16 gauge studs. The failure mode has been tested and found to be in the stud buckeling. Must the top and bottom plate be 16 gauge as well or does this remain 20 gauge as the remainder of the structure. The builder of our homes (before I was hired to engineer them) obtained his materials pre-cut from Steelers. All top and bottom plates where supplied as 20 gauge with studs of thicker gauge (16ga) in areas used for shear. The only problem that I have come across is the problems making the connection of the plywood to the top plate using Ply-Driller screws. Inasmuch as the plates are thiner than 18 gauge, the special screw flange does not shear off and widens the hole in the steel stud as well as the plywood - making a poor connection.
There are many issues regarding standards in Steel Stud framing that are not yet addressed by LGSEA. I could use the help of our listservice participants to develop some mininimum design guidelines as well as some standardized methods of analysis. I would be happy to convert the analysis into either spreadsheets or MathCad models for use by anyone who is designing steel framing.
Please let me know your opinions on this issue. I'm sure that those of you who are members of LGSEA will agree that this is a needed tool and that LGSEA would appreciate the help.
Dennis S. Wish PE
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