×
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

Related Articles

Jobs

Intermediate Moment Frame Connection

Intermediate Moment Frame Connection

Intermediate Moment Frame Connection

(OP)
Intermediate Moment connection requirements.
- I have project where the intermediate moment frame is not braced at the bottom flange as per the AISC requirement near the support. The top of beam is braced by the concrete planks. My question is if the bottom flange of beam is not braced is there other design requirements i could verify to see if the connection design is still acceptable. Any suggestions would be appreciated.

Thanks,

RE: Intermediate Moment Frame Connection

Could you tell us more about why you can't provide bracing? Many of the prequalified connections in AISC 358 allow the plastic hinge bracing to be ommitted where the beam supports a concrete structural slab that is connected to the beam with welded shear connectors at 12" o.c. You may be able to detail the plank to beam connection in a way that provides a convincing torsional stabilizing effect.

RE: Intermediate Moment Frame Connection

(OP)
I received the steel shop drawings after contractor started erecting the steel on the site. These location has high ceiling and i could not add angle brace below the beam. Can the concrete plank be treated as structural slab? I was thinking of adding angle braces on both sides and beam to conform the torsional requirement but this will be adding lot of angles and still not convinced with if this will be effective.

RE: Intermediate Moment Frame Connection

Quote (RDMESH)

Can the concrete plank be treated as structural slab?

Whether you can rely on the planks as a structural slab that torsionally braces the beam depends on how they are connected to the beam. If the beam is detailed for composite behavior with shear studs spaced at 12" o.c., then possibly. If not, you will need to add discrete bracing.

Quote (RDMESH)

These location has high ceiling and i could not add angle brace below the beam.

Quote (RDMESH)

I was thinking of adding angle braces on both sides and beam to conform the torsional requirement but this will be adding lot of angles and still not convinced with if this will be effective.

So the bottom flange extends below the ceiling and the bracing needs to be kept above the ceiling, is that correct? You could add bracing beams above the ceiling connected to full-depth stiffeners in the frame beam. The stiffeners would need to be designed as cantilevers to carry the bottom flange brace force up to the bracing beam connection. Design examples are discussed here: Link.

I'm confused by your comment about adding a lot of angles. Was the bracing omitted only at the plastic hinge locations or along the entire length of the beam? The slab is only effective at bracing the plastic hinge location near the column. Discrete bracing would be required between the hinges.

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


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