×
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

Round stirrup in 4-bar configuration in a round column??

Round stirrup in 4-bar configuration in a round column??

Round stirrup in 4-bar configuration in a round column??

(OP)
My fabricator would rather do a circular tie than a square tie.  Is it permissible to do this in a circular column if I only have four vertical bars?.......or is there some place in the code that I'm not seeing that specifies that one must use a square stirrup for only 4 vertical bars?

Thanks   

RE: Round stirrup in 4-bar configuration in a round column??

If the column is small, I see little problem with this, particularly if it is non-structural.  In fact, the circular ties would be closer to the outside of the column, better able to control cracking.  

That being said, however, I never use less than 6 in a circular column.  Just personal preference here.  I also don't allow the lateral spacing between the bars to exceed 6".

Mike McCann
MMC Engineering

 

RE: Round stirrup in 4-bar configuration in a round column??

ACI 318-08 seems to allow this per 7.10.5.3:

"Where longitudinal bars are located around the perimeter of a circle, a complete circular tie shall be permitted."

The argument could be made that the circular tie with 4 bars violates the 135° limitation of 7.10.5.3, since the circular tie would be tangent to the bar.  However, I am not sure I would make that argument.

RE: Round stirrup in 4-bar configuration in a round column??

For circular ties, the 135 degree restriction does not apply as no circular tied arrangenent would qualify.  That's where the spiral tie design comes into play.  

If you want circular ties, do not allow lap splices of the ties, but normal bent ends - 180 and 90 - and have the contractor alternate where these coneections to the vertical bars occurs along the length of the column.

Mike McCann
MMC Engineering

 

RE: Round stirrup in 4-bar configuration in a round column??

msquared48,

I agree with you.  The philosophical question is whether the ties are in a square pattern or four-on-a-circle.  That is the point I was trying to make (rather poorly).

RE: Round stirrup in 4-bar configuration in a round column??

(OP)
Thanks for the feedback!  Sounds like I can do this then.  

msquared48, is there a problem with just butting the ends of the tie together and welding the stirrup?

I'm using these concrete piers in an application where I'm trying to raise TS columns above the animals that occupy the same space.  Due to customer preferences, I have a pier that is WAY bigger than it really needs to be.....hence my question a week or two ago regarding minimum reinforcing steel below 1% of the gross area.

My biggest issue on these piers really is uplift..........and making sure that the forces in my steel column get transfered down to the spread footing below.  Due to the MWFRS design that I'm using, there's hardly even any shear at the base of the TS column / top of conc pier so I'm really not stressing things out in compression that much.

What do you think about the welding?

Thanks.

RE: Round stirrup in 4-bar configuration in a round column??

Mike,
Curious why you say that you can't have 135 degree hook on circular ties.  Done all the time, just not on the same bar like at a corner in a rectangular column.

RE: Round stirrup in 4-bar configuration in a round column??

Some codes actually require a minimum of 6 bars in a circular column. I think it is in BS8110, but it may be Eurocode.

If you use 4 bars, you would have to check the capacity at different rotations of the bar pattern (single bar at top or 2 bars at top) to determine the lowest capacity.

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