Smart questions
Smart answers
Smart people
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Member Login




Remember Me
Forgot Password?
Join Us!

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips now!
  • 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!

Join Eng-Tips
*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Donate Today!

Do you enjoy these
technical forums?
Donate Today! Click Here

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.
Jobs from Indeed

Link To This Forum!

Partner Button
Add Stickiness To Your Site By Linking To This Professionally Managed Technical Forum.
Just copy and paste the
code below into your site.

abusementpark (Structural)
17 Dec 11 10:55
Can anyone tell me which ACI document defines how rebar lap splices are required to be tied (i.e. how many ties, spacing, etc.), assuming there is a requirement?

Also, what is the difference between a regular lap splice and "development" splice where the bars are not tied?  
ron9876 (Structural)
17 Dec 11 14:15
Not a requirement unless you are doing something unusual.

Development length is the length required to embed a bar into concrete to develop it. A lap splice is the length required to overlap bars to transfer load from one bar to the other.

ACI318 has requirements.
msquared48 (Structural)
17 Dec 11 15:46
Just tied sufficiently to maintain the alignment of the bars, to include the lap requirement, and keep the cage from falling apart during the pour.   

Mike McCann
MMC Engineering
http://mmcengineering.tripod.com
 

DST148 (Structural)
17 Dec 11 20:48
abusementpark: Your question has already been answered as above.
As an aside: Reference ACI 318-05. The general development length equation has a parameter that represents the contribution of confining reinforcement. ACI gives two-tier approach for calculating development lengths. Section 12.2.2 is a simplified approach. Per this section stirrups or ties are not required per say, but if you want to take advantage of the presence of ties then they have to conform to the code minimum.
Section 12.2.3 represents the general development length equation. Here transverse reinforcement index is calculated based on area of ties, spacing of ties, and the number of bars being developed or spliced. The development lengths, and in turn the splice lengths, can be significantly reduced by taking advantage of the presence of the confining reinforcement. The designer has an option here.
    
hokie66 (Structural)
18 Dec 11 1:29
Don't confuse tie wire to hold the bars in place for placement with structural ties which confine the reinforcement.
DST148 (Structural)
18 Dec 11 8:51
hokie66 - I agree that I should have said ron9876 in place of as above in my post. There is no confusion between tie wires and ties here.
 
TXStructural (Structural)
18 Dec 11 22:05
ACI 318-11 7.8.1, in part: "Reinforcement...shall be accurately supported before concrete is placed, and shall be secured against displacement within tolerances..."
In general, the bars should stay in place, or deflect under the weight of workers and construction loads (like wheelbarrows) and then rebound to the required position when the load is removed.  Tying of bars, in all cases, is "temporary" and ONLY required for maintaining location during construction and in wet concrete.  Wire ties have no effect on design, or on installed performance.

Caution, sales pitch: For field personnel, CRSI's "Placing Reinforcing Bars" covers most placing issues encountered by placers and inspectors.
abusementpark (Structural)
20 Dec 11 21:59

Quote:

Development length is the length required to embed a bar into concrete to develop it. A lap splice is the length required to overlap bars to transfer load from one bar to the other.

So when I overlap bars to transfer tension, they don't have to be tied?  For instance, can I lap bars but have a couple inches of space between them and still transfer the tension?
TXStructural (Structural)
20 Dec 11 22:39
That is referred to as a noncontact lap splice, and it is acceptable. ACI 318 paragraph 12.14.2.3 covers this.
ToadJones (Structural)
20 Dec 11 22:49
abusement-
I think this is similar to the approach I use when developing anchor rods with high tension loads.  
abusementpark (Structural)
20 Dec 11 23:14

Quote:

That is referred to as a noncontact lap splice, and it is acceptable. ACI 318 paragraph 12.14.2.3 covers this.

Ok, I will check that section out tomorrow when I get to the office.  Thanks!
 
abusementpark (Structural)
20 Dec 11 23:14

Quote:

abusement-
I think this is similar to the approach I use when developing anchor rods with high tension loads.  

Exactly.  I usually apply the same logic.  I just wasn't sure if it was "codified."
DST148 (Structural)
21 Dec 11 9:29
abusementpark: noncontact lap splices are permitted subjected to the limit of 6" or one-fifth the splice length whichever is less. The commentary clarifies that most research was conducted with reinforcing within this spacing.
Moreover noncontact lap splices are permitted only in flexural members. My understandng is that noncontact lap splices would not be applicable in (direct) tension members.  

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!

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