Lightgage Framing Design
Lightgage Framing Design
(OP)
What references do you use to design lightgage or cold formed steel members? I have the SSMA Product Technical Information guide. Also have the AISI Cold Formed Steel Manual but think it's one of the most poorly organized books ever written. I'm looking for something a little more practical. Any recommendations would be great.
thanks
thanks






RE: Lightgage Framing Design
I do not think that you will find any material that presents cold-formed in an easy to do manner. The material is just too complicated.
If you keep the stuff sheathed on both sides it will work fine. If the stuff has any unbraced length beyond about 36 in you are going to trouble
RE: Lightgage Framing Design
http://www.clarksteel.com/
Good luck!
RE: Lightgage Framing Design
Of course, there is always software. You'll find several programs available but few that also check web crippling. If you can find one that does it all it may worth having.
RE: Lightgage Framing Design
RE: Lightgage Framing Design
DaveAtkins
RE: Lightgage Framing Design
Follow DaveAtkins advice, call Dietrich and order one of their catalogs. They have more information than any other supplier I have seen in their new catalog. They also have a bunch of pre-fab connections with allowable load tables for just about any condition.
Remember to check combined bending and shear, bending and web crippling in the negative moment areas one of these two cases will control 90% of the time.
RE: Lightgage Framing Design
RE: Lightgage Framing Design
RE: Lightgage Framing Design
RE: Lightgage Framing Design
Be careful SSMA studs are their own thing, they have different properties than there C-Stud counterparts. They also have punched holes along the length of the member.
Their may not be a reduction at 6', 36" is just a rule of thumb
RE: Lightgage Framing Design
Also be careful when using published tables. Always make sure you read the general notes and footnotes and agree with all the assumptions used to generate the tables.
Some software we use is CFS by RSG Software
Some good sites to reference for cold formed steel (light gauge)
Cold Formed Steel Engineers Institute
Steel Framing Alliance
And for anyone and everyone designing / specifying cold formed steel, I highly recommend you read and reference the code of standard practice
AISI Code of Standard Practice
RE: Lightgage Framing Design
The properties for SSMA are a little different C-Studs in the AISI Manual
RE: Lightgage Framing Design
CFSEng, good post.
As for no reduction at 6' unbraced length, that must have been quite a massive stud. Most will have some sort of reduction for LTB around 3-4 feet and smaller studs and tracks maybe less. that's why it is important to do the engineering instead of rely on rules of thumb.
RE: Lightgage Framing Design
None of the drywall contractors I work with use the SSMA designations. Therefore, on the shop drawings I produce, I use the "traditional" designations--e.g., 6" X 16 GA. I'm not saying I'm right--I'm just being practical.
DaveAtkins
RE: Lightgage Framing Design
Some things we did to help our clients was contact SSMA and get permission to put a copy of the inside cover of the SSMA Product Technical guide into our submittals. And we put a copy of the 'Thickness - Steel Components' table in our submittals so they can convert from mil thickness to gauge. We also try and get kick-off meetings for projects and bring copies of the SSMA guide with us and explain how to read the designations.
I guess my point is, just be sure they are using what you designed.
RE: Lightgage Framing Design
On the one hand, I understand DaveAtkins' practical approach to the situation. On the other hand, I agree with CFSEng in that the SSMA system is much more specific than than the old system and we need to make sure we are getting what we designed. This product so widely used we should have a common system in the industry, just like structural steel. Unfortunately, the stud manufacturers make their money from construction contractors, not engineers (we're not the ones buying their product), so they are going to accomodate their customer base. I have found stud manufacturers that have tables using both systems, but that still doesn't force the construction contractor to learn the SSMA system.
I guess the only way we can deal with this situation is to follow what CFSEng does. Train each contractor individually.
RE: Lightgage Framing Design
I am a proponent of SSMA designations only...then again, I feel no sympathy for those who don't keep with the times.
The book by Yu seems to be what I'm looking for, thanks for the heads up.
RE: Lightgage Framing Design