×
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

Axial load level as a percentage of Buckling load?

Axial load level as a percentage of Buckling load?

Axial load level as a percentage of Buckling load?

(OP)
Dear forum members,

I would like to know the level of axial load of a column (or beam) in a concrete or steel frame at service conditions as a percentage of buckling load.(1%, 10%, 50% or what?) Any body has an idea?

Pls help. Thanks very much.

Luke

RE: Axial load level as a percentage of Buckling load?

Euler buckling direct calculations for a specific case are straight forward, for steel. Here is a link to use as a guide
http://physics.uwstout.edu/statstr/statics/Columns/colse61a.htm

Allowable column loads are given in Section 3 of AISC Manual of Steel Construction (ASD).

Then a comparison of the two values can be made.

It is unfortunate that the W10x29 size member used in the example at the link above is not modern size (with listed allowable concentric loads), but the principle can be applied to a listed member.

www.SlideRuleEra.net reading

RE: Axial load level as a percentage of Buckling load?

For an "idealized" steel column perfectly straight braced at the top and pinned at the bottom I beleive the safety factor to around 2. The AISC Manual Specs uses 12/23 when KL/r exceeds Cc as its reduction. You can easily compare each of the results. For a reinforced concrete column I have no idea as to the ACI built in safety factor.

RE: Axial load level as a percentage of Buckling load?

(OP)
Thank you guys for your replies,

But I was just wondering about the ratio of the axial load present at that column (not the capacity of the column) to its buckling load.

Thanks so much for your input :)

RE: Axial load level as a percentage of Buckling load?

lukeme...compute the buckling load using Euler's column buckling equation.  Then divide your actual axial load by the critical load and that's the ratio you're looking for.

RE: Axial load level as a percentage of Buckling load?

that's a bit obvious (isn't it?) ...

i think lukeme is after a design guide line for a column allowable (as a percentage of the euler load)

i think it depends on your industry ... i'd be reasonably happy working to 50% to 80% of euler ... anything more i'd want a test.  also airplanes are usually more sensitive to local column failures (crippling), and remember that euler critical loads are unreasonable for short columns (refer to euler-johnson)

good luck

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