×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

OWSJ KL/r

OWSJ KL/r

OWSJ KL/r

(OP)
I am designing some 18" OWSJ, for the KL/r the steel handbook says r is the radius of gyration. I have tried using it for round bar and my web comes out extremely big, but if using the actual radius of the bar the web of these joist come out reasonably sized.

I am wondering which one is the correct one or if both ways are possible. Can anyone help?

Thank You

RE: OWSJ KL/r

no way you should use actuall r. You have to use r= SQRT I/A. there is some short cut like .3d. cnfirm it.
Check if units are compatible.

RE: OWSJ KL/r

Why are you trying to design an OWSJ?  Are you trying to back check a design provided by a manufacturer?

RE: OWSJ KL/r

(OP)
Checking the design of a fellow engineer. So then by using this radius of gyration to find lamda, I inserted it into the Cr = 0.9AFy(1+λ^(2n))^(-1/n)
to find the compressive resistance of the web member in compression. I think this is the right procedure, Please correct me if I am wrong. If right I will have to chech my math again.

Thank You.

RE: OWSJ KL/r

I assume OWSJ means Open Web Steel Joists.... And that you are from the US.

Maybe I don't know what the procedure is, but when I have to verify the numbers coming from a manufacturer I refer to my Vulcraft Catalog:

http://www.vulcraft.com/downlds/catalogs/joistcat.pdf

Check page 11 to 15 for the SJI design requirements for K series joists.

Hopefully this will help.
 

RE: OWSJ KL/r

Careful!  As dgkhan states, you must use the radius of gyration, not the radius of the bar!  Also, your formula for the "compressive resistance" doesn't seem right. You need to check again more than your math.

RE: OWSJ KL/r

The formula Cr = 0.9AFy(1+λ^(2n))^(-1/n) is correct for doubly symmetric shapes according to the Canadian code.  For hollow sections, n = 1.34.

Perhaps the easiest would be to post your calculation for a typical web member.  It is not difficult to check.

BA

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources