×
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

shearwall vertical reinforcing vs crossties ?

shearwall vertical reinforcing vs crossties ?

shearwall vertical reinforcing vs crossties ?

(OP)
I'm inspecting on a job right now, high rise CIP concrete, with lots of shearwalls.

One of the shearwall notes reads:

CROSS TIES ARE REQUIRED WHERE AREA OF SCHEDULED VERTICAL REINFORCEMENT
EXCEEDS 0.01 TIMES THE GROSS CONCRETE AREA OF THE WALL. IF CENTER TO
CENTER SPACING OF VERTICAL BARS IS 6" OR SMALLER, CROSS TIES SHALL BE
PLACED AT EVERY OTHER PAIR OF VERTICAL BARS; OTHERWISE, ALL VERTICAL BARS
SHALL BE CONFINED WITH CROSS TIES.

The plan view detail, of course, shows neatly placed #3 cross-ties confining #9 vertical bars; however, in real life there is a 66" lap splice and a #3 bent into a 135-degree hook is never going to wrap around #9's spliced side-by-side.

So I'm curious, out of all the CIP shearwalls I've seen over the years, I've never seen SW verts dog-legged similar to column vertical bars so that the bars can be spliced front-to-back instead of side-to-side.

Is there something in ACI-318 that disallows vertical bars in shearwalls from being dog-legged?

RE: shearwall vertical reinforcing vs crossties ?

There's nothing in 318 that disallows "dog legs" in shear walls. In your case, with real world physical conditions, the vertical bars in the shear wall would have to be lapped on the front-to-back as you say to work with the hooks.

Othwersise, if side-to-side laps are preferred, then the cross ties would have to be altered to be a series of rectangular ties (like in a traditional column) and wrap around pairs of bar lines. Even with that, the corner of the tie may have to wrap on a dummy vertical bar or something. I've rarely had ties in shear walls so I may have to think about that.

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

RE: shearwall vertical reinforcing vs crossties ?

I am willing to bet the placer and fabricator are ahead of you on this. Discuss it with them.
There is seldom a need for an offset bend, but they can be used in congested walls. Also remember that lapped bars do not have to be in contact so the hook can go around one bar but not the other unless the design calls for ties around all bars.

RE: shearwall vertical reinforcing vs crossties ?

@TXStructural: I almost gave the same answer regarding the nob-contact lap splices. I rejected it because the ties are invariably for the lap compression condition rather than the tension lap condition. Under compression, the one bar of the lap not engaged by the tie hook would be prone to buckling out of the wall.

I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.

RE: shearwall vertical reinforcing vs crossties ?

Many things affect restraint, including whether it is the vertical or horizontal bar that is on the outer layer. In this case, some restraint is provided by cover and some by the horizontal bars. In pre-tied walls, it is unreasonable to expect every vertical bar to line up from one cage to the next, so a non-contact lap condition should be anticipated. If the laps are non-contact, the designer can specify if every bar in the lap requires a tie or how to handle the situation. If there is sufficient cover, tying the outer layer could be useful, but this would be unusual.

In the OP, the note says that bars spaced 6" or less, as would be the case with non-contact laps, require ties on every other bar. I would interpret this to mean that there will be ties on every other bar along the non-contact laps. The rebar detailer may or may not provide enough ties for this condition, so I would discuss it with the supplier or placer early in the project.

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