×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

Custom Shape Axial Capacity

Custom Shape Axial Capacity

Custom Shape Axial Capacity

(OP)
Hey All, (Likely Josh)

I've created a reinforced w-column using RisaSection, it calculated all the properties correctly (from what my quick hand check suggest). We are adding plates to the flanges to keep the shape symmetrical.

I've also successfully imported said section into R3D including all properties (J and Cw included). However, when checking the axial capacity it was in the range of 10x lower than my hand calcs suggest it should be. That is even with unbraced length set to zero.

So I then modelled just a very basic pinned column with a singular load, again unbraced length set to zero, and it returned a capacity 10x lower than expected.

Anyone ever come across this before? I've attached my test run.

In the end, this reinforcing is actually going to be applied to a pre-eng steel frame, however this axial capacity issue is causing the reinforced frame to be weaker than the original in the model. Which the hand calcs don't agree with.

RE: Custom Shape Axial Capacity

It's not possible for me to tell for sure. But, I'm going to guess that the issue is related to the thickness that RISASection is passing to RISA-3D for the flange or web.

RISASection is very good at calculating A, I, the plastic section properties and such. But, when it has to figure out what the thickness of a built up flange is, it can be difficult. We recognize this, though and give you (within RISASection) the ability to override these two values. See attached image.

My guess is that we interpreted the flange thickness as significantly too small. This would result in local buckling controlling the capacity of the member.

RE: Custom Shape Axial Capacity

Actually, I was wrong. The web is coming out slender, not the flange. So, it's likely the web thickness that needs to be set manually in RISASection.

RE: Custom Shape Axial Capacity

(OP)
Ah yes,

That appears to have solved it.

Thanks,

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! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close