×
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!

*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

Is stacked X-brace same as K-brace

Is stacked X-brace same as K-brace

Is stacked X-brace same as K-brace

(OP)
thread507-422360: Is a Staked X brace the same as a K Brace

I have a one-story structure with stacked X-bracing same as the referenced thread above. I am not understanding how it is not a K-brace. The definition from AISC Seismic Design Manual (5.2) states: where a brace frames to a column at a location where there is no out-of-plane support. Is it a K-brace condition?

RE: Is stacked X-brace same as K-brace

I don’t think so. A K-brace is a problem because the horizontal component of the brace goes directly into the column creating a bending moment. In a stacked X-frame the horizontal component goes to the brace below which basically provides the out-of-plane support.

RE: Is stacked X-brace same as K-brace

Agree with Edub24 - a K brace is a column with axial load and a lateral force resisted in bending. When the column goes inelastic, it buckles and collapses the structure.

A double-stack X brace is simply a vertical truss - when it goes inelastic it can still achieve post-yield stability unlike the singular column.

Check out Eng-Tips Forum's Policies here:
FAQ731-376: Eng-Tips.com Forum Policies

RE: Is stacked X-brace same as K-brace

My thoughts on this. Some of it is semantics.
1) We're talking about R = 3 vs R = 3.25, right? Because we're thinking OCBF vs a non-341 system. For industrial structures I usually just start out assuming R=3.
2) Is it the height limits that are causing concern? If it's a non-building structure then the normal height limits are relaxed a good amount depending on what you call it.
3) I don't 100% agree with the interpretation in that article. But, I understand where it's combing from. If you had a beam at the intermediate levels then there is no question that it's an X brace. If not, then it may not qualify as an OCBF. I would never personally call it a K brace, but I understand why he takes the crappy code definition of a K brace and applies it to that situation.... Rather I would say that the column isn't sufficiently braced at that level to qualify for OCBF.

RE: Is stacked X-brace same as K-brace

(OP)
Thanks to everyone for your responses!

RE: Is stacked X-brace same as K-brace

The article is incorrect, the configuration is a multi-tier BF not a K-frame. Design criteria for multi-tier BF; OCBF. SCBF and BRBF can be found in the latest edition of the AISC 341.

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