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tension compression splice

tension compression splice

(OP)
What's the difference between a splice, a tension splice and a compression splice?

The plans I'm looking at says use 30 bar dia.  But then, right below it, it says to use a Class B tension splice in accordance with ACI 318.

The typical detail says "splice top and bottom bars as shown"  It's nothing out of the ordinary.  I have a multi span grade beam supported by drilled piers.  Top bars lap at midspan and bottom bars lap at support.

So do I apply the 30 bar dia lap or the tension class B lap?  I looked thru the ACI manual and it doesnt give me a definition nor does it tell me when to apply one or the other.

RE: tension compression splice

The use of bar diameters isn't always consistent with the ACI development lengths or splice lengths.

I would use the specified Class B splice as that may be (probably will be) longer than the 30 bar diameters.

A splice is a way to take two separate bars and connect them or overlap them such that they work equivalent to a single bar across a specified location, such as a joint.

A tension splice is simply a splice that is dealing with bars in tension.

A compression splice is simply a splice that deals with bars in compression.

Splices can be overlapped bars (per ACI chapter 12) or mechanical connectors such as this:  http://www.erico.com/products.asp?folderid=45
 

RE: tension compression splice

In addition, if you are having issues with rebar congestion, you can also use mechanical splices.  Designing with mechanical couplers is much easier than lap splices since a few of the manufacturers are capable of developing at least the yield strength of the reinforcing bars that are being joined.  Quite often, 125% of Fy is specified in tension or compression. It's also important for the manufacturer to have an ICC report, which certifies that they've gone through the testing as per the latest codes. In previous projects, I've specified Bartec Mechanical Couplers and End Anchors by Dextra Group. They have an office in California.  

RE: tension compression splice

ACI 318-08 section 12.14.3.2 requires that "full mechanical splices" develop tension and/or compression of at least 1.25 fy of the bar.  Some splices are designed for compression, some for tension, and some for both.

Lap splices are prohibited for most uses of bars larger than No. 11 by ACI 318-08 paragraph 12.14.2.1.

318-08 section 12.15.1 specifies that Class B laps are 30% longer than Class A splices.

Section 12.15.2 specifies that Class B is required except in certain instances.

In current practice, some engineers are permitting splices where previously prohibited, based on the thinking that Class B splices assure that all reinforcing is fully developed in all sections beyond the initial development length at discontinuous ends.

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