×
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

Lr for Channel Capped S shape

Lr for Channel Capped S shape

Lr for Channel Capped S shape

(OP)
I've been banging my head on this one, working through the 13th manual for a rail beam and I'm pretty sure my answer isn't right.  Using the equation at the bottom of page 16.1-50 in the 13th AISC, I have:
rt = 0.614
E = 29000
FL = 31.3
J = 696.5
Sxc = 105
ho = 14.3 (rough calc)

I'm getting 1068" or 89 feet!  Any ideas on where I'm screwing up would be helpful...

Of course, any tables for S15x42.9's capped with C10x15.3's would be even better...

As a check, I ran equation F2-6 with a W14x82 (similar depth and top flange width) and got 397" or 33'.  I know my capped S should have an Lr longer than this, but not 2 1/2 times longer.

RE: Lr for Channel Capped S shape

Check all your units.

Try giving us some informaiton on how you got rt, FL, ho, and so on.  The more we have the easier it is to help trouble shoot.

RE: Lr for Channel Capped S shape

(OP)
Sorry - idiotic mistake - I used polar moment of inertia instead of torsion constant for J.  A common booboo...

RE: Lr for Channel Capped S shape

that was the first thing that jumped out at me....J seemed to high

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