×
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

Another Thread on Lap Splice Length in CMU

Another Thread on Lap Splice Length in CMU

Another Thread on Lap Splice Length in CMU

(OP)
Let me begin by saying that I still specify 48 bar diameters for lap splices in CMU (yes, I know the IBC requires longer lap splice lengths for bars > #5).

Anyway, the Contractor on one of my projects called to say that he is using #6 X 7'-0" long bar lifts (he said you can't lift the blocks any higher than 7').  He builds 4'-0" of CMU, then grouts the CMU, then installs the next bar lift, lapping it 3'-0" with the bar below.  What ends up happening, starting at the bottom of the wall, is you get a single bar for 4', two lapped bars for 3', a single bar for 1', two lapped bars for 3', a single bar for 1', etc.  The Contractor thought this was strange, but I told him it is correct.

Now, just for fun, I calculated the more correct lap splice length for a #6 bar, using IBC, and came up with 48".  If I had used this lap splice length, almost the whole height of the wall would be lap splices!!!

Does anyone else think this is RIDICULOUS???

DaveAtkins

RE: Another Thread on Lap Splice Length in CMU

DaveAtkins,
I had a similar discussion with a mason yesterday. He also said that 7' was the maximum lifting height which seems fairly obvious and reasonable.

As for the situation you describe above, I usually avoid it by using mechanical splices for two reasons. First, I agree that the required lengths are not always practical and can lead to a waste of rebar. Many engineers dismiss mechanical splices because of a perceived increase in cost compared to lap splices. But just look at how much additional rebar you are using. At some point, mechanical splices become less expensive

The second reason I like mechanical splices is you get a higher quality splice. Too many times I have seen a mason carelessly pound rebar into grout for a splice. Maybe it ends up in the correct position, maybe not. Even if the mason is careful to place the splice bar, it can become displaced when the cells are filled with grout.

For your projects that must adhere to the IBC, how do you justify the shorter lap length?

RE: Another Thread on Lap Splice Length in CMU

(OP)
MotorCity,

Good point about mechanical splices.  I will begin to think about using them.

I really can't justify, per Code, using lap splice lengths based on the old ASCE/ACI 530.

DaveAtkins

RE: Another Thread on Lap Splice Length in CMU

I prefer mechanical splices not just for CMU but for concrete as well.  most contractors don't like them because they are unfamiliar with them and think they will cost more.  However, I was adamant about using them on one project several years ago even tho the contractor fought hard not to use them.  after about half way thru the project, the contractor told me he was glad I insisted.  

RE: Another Thread on Lap Splice Length in CMU

DaveAtkins:

We more than agree that the masonry lap splices are ridiculus for #6's and above. We try to avoid #6's (or bigger) if we can just to avoid the splice length problem.

I guess I am wondering why ACI changed. Were masonry walls falling down becasue of improper splices? Or is this a solution in search of a problem?

RE: Another Thread on Lap Splice Length in CMU

Mechanical splices are more expensive.  How do you justify the cost?  What specific splice do you specify for masonry construction?  For concrete construction?

I have specified them to help with the installation of reinforcing.

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