×
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

Steel Frame Erectors:Temporary Bracing?
2

Steel Frame Erectors:Temporary Bracing?

Steel Frame Erectors:Temporary Bracing?

(OP)
Consider a 4-storey building with glass cladding required by architects. No bracing is accepted, but shear wall is accepted around stairs. So the structural system defaults to steel columns with simply supported beams to carry trapezoidal deck topped with concrete serving as floor, and lateral stability is guaranteed by shear walls. Now here is the problem:

Steelwork will be erected first and concrete for shear wall and floors will be poured later. So how will lateral stability be guaranteed as concrete is poured? Some form of easy to remove temporary bracing?


Thanks in advance.

RE: Steel Frame Erectors:Temporary Bracing?

Bracing will obviously be needed.  For simplicity just bolt your bracing to the columns.  But simplicity is not necessarily your primary concern as the holes left in the columns after you remove the bracing will be visible through your glass cladding.

So, why not make your beam/column connections into moment connections with sufficient capacity to carry construction based sway loads. The shear walls will be in place before the cladding is erected (presumably).

Otherwise, insist that the shear walls are constructed first.

Regards

Andy Machon
Andy@machona.freeserve.co.uk
 
 

RE: Steel Frame Erectors:Temporary Bracing?

(OP)
Thanks Ginger for immediate response

RE: Steel Frame Erectors:Temporary Bracing?

(OP)
Andy, how about connecting bracings to beams, again bolted but eccentrically?. I can hide the connections on top of beams with concrete topping and below beams with false ceiling. Should work, shouldnt it

Thanks

RE: Steel Frame Erectors:Temporary Bracing?

IJR,
Provided u have the scaffolding in place I do not anticipate any problem due to lateral forces. Have the scaffoldings in place until u finish all concrete works ie shear walls and slab.
I am supposing that u have a braced structure with shear walls taking all lateral forces. R they wind only? As I have understood the shear walls are located around the stairs. Is there appreciable eccentricity between shear walls and building centroid? U need to check torsional response as well against the minimum allowed. ( 2.5% width - BS )
I would suggest u design for a dual system with both frame and shear walls resisting lateral loads.  
Hope this is not scary
Riz

RE: Steel Frame Erectors:Temporary Bracing?

(OP)
Thanks Riz and thanks for the spreadsheet too.

 I can take care of the torsion. No problem. And seems  you and Ginger think of moment connections as sufficient. And I will probably do that.

Now how should I design the moment connections?. I am designing not for wind but for seismic effects of high intensity(eq to UBC Zone 4) and I was thinking using wind moment connections (angles attached to flanges) will stabilize my structure during pours of concrete. You think that would work. Design for wind.

Next, wont moment connections be more expensive than temporary scaffolds(bracings.

Thanks once more and again

RE: Steel Frame Erectors:Temporary Bracing?

IJR:

Are your shearwalls cast-in-place concrete?  Usually, the concrete "shafts" that serve as lateral resisting systems in buildings such as yours are constructed first, prior to steel going up.  The shaft serves as a lateral brace for all the framing during and after construction.  The contractor simply jump-forms the shafts.

Once the shafts are constructed, the steel framing (Non-Self Supporting Steel Frame per AISC definition) is erected.

Another issue.....usually in the U.S., the means and methods of constructing a framed building are the domain of the contractor or erector (See AISC Code of Standard Practice, Section 7.9.3).  Are you the engineer-of-record and/or are you working for the contractor/erector?  

RE: Steel Frame Erectors:Temporary Bracing?

(OP)
Thanks very much JAE.

I have no word against the contractor as to how he will pour concrete and he insists that he will cast shear walls in place together with concrete on floor decks only after steel erectors have finished(and may be quit the site)

In my opinion your reasoning is more logical. But this seems to be a difficult case.

Thanks once more and again. Nice weekend

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


Resources

eBook - 10 Reasons to Choose CATIA on the Cloud
To compete in today’s fast-paced and competitive market, smaller and newer firms need a powerful platform that will enable them to compete with bigger players, without the heavy investments needed in computer hardware, software and personnel. Download Now
White Paper - Smart Manufacturing for Electronics
This white paper describes a transformative approach to electronics manufacturing made possible by the addition of Mentor Graphics to the Siemens family. It describes a completely digitalized strategy that supports both printed circuit board (PCB) and mechanical design and manufacturing, uniting the entire product lifecycle – from idea and production to customers and back. Download Now

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