×
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

Manually calculate beam “k” values for older sections?

Manually calculate beam “k” values for older sections?

Manually calculate beam “k” values for older sections?

(OP)
I’m designed new steel to fit within a steel building composed of shapes from ASD 7. The properties for these shapes are given in the historic shape data spreadsheet on AISC’s website. Unfortunately the spreadsheet does not include K or T values. It does have the d and tf values though. Is there a rule of them for the ratio of T/d or k/d? If not is there a general radius size between the web and flange that I can add to tf to get a value for k?

RE: Manually calculate beam “k” values for older sections?

What exactly do you need to know the k for? is it so coped beams can fit under existing steel? I would think you could assume a k = 2*tf and be conservative in general, as I flip through the steel sections.

RE: Manually calculate beam “k” values for older sections?

If it's existing steel, you could go measure it.

RE: Manually calculate beam “k” values for older sections?

StructureMan44:
The “k” value has been shown in the AISC Manuals all long. The earliest one which I have right at hand is a 1958 printing, and the latest edition which I have also has them tabulated.

RE: Manually calculate beam “k” values for older sections?

(OP)
StructSU10: if k=2*tf is conservative enough I'll use that, thanks.

JStephen: It is existing but it's in another state and there are many difference sizes in use.

dhengr: I don't have any manuals older than the 13th edition, I've only used the AISC spreadsheets: http://www.aisc.org/content.aspx?id=2868

RE: Manually calculate beam “k” values for older sections?

Here is what I've done before: It's not exactly accurate, but it is a simple concept that will get you in the ballpark. You might be off by 20 or 30%, but you won't be off by a factor of an order of magnitude.

Calculate the area of the member (based on d, tw, bf and tf) subtract that from the area given in the table. Any extra area is equally split among the k areas. Assume them to be simple triangles and you've got a reasonable approximation of the k areas.

RE: Manually calculate beam “k” values for older sections?

(OP)
It looks like k=2*tf may not be conservative, it may need to be 3*tf or 4*tf. Maybe there is general rule for the radius size?

RE: Manually calculate beam “k” values for older sections?

(OP)
It appears that every k value for the versions available in AISC historic database (for the 14th edition, 13th edition, LRFD 1-3, ASD 8,9) is less than 3.1*tf.

RE: Manually calculate beam “k” values for older sections?

StructureMan44:
Well, there you are..., you have developed your very own rule of thumb for something. It’s yours, use it at your own discretion and risk. In the mean time, most of us will probably continue to look in the AISC Manual for that info. since it has always been tabulated there with all the other section design dimensions, or detailing dimensions.

RE: Manually calculate beam “k” values for older sections?

(OP)
JoshPlum: That's a very good idea and more accurate than my idea, thank you.

dhengr: I agree, I would use the tabulated data if I had the ASD 7 manual

RE: Manually calculate beam “k” values for older sections?

AISC offers some of the older manuals free to download for members.
See: Older Manuals

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