What's the recommended connection method of reinforcement bar in beam

[johnthy]

According to Clause 12.14, ACI 318-08

The splices of reinforcement bar can be lap spilce, mechanical and welded spices.

Now I want to know what is the first choice of reinforcement bar splices for beam in site.

Thank you!!

 

[msquared48]

Staggered lap splices if the structural conditions permit.

Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask

 

[Ron]

Agree with Mike. Lap splices are most common.

 

[rowingengineer]

agree with rona nd Mike for small/medium bars sizes.

An expert is a man who has made all the mistakes which can be made in a very narrow field

 

[TXStructural]

Assuming no unusual circumstance, always lap splice, and to the extent it makes sense, class B tension lap splices everywhere. You should not lap splice large compression bars.

For certain conditions, you may want to consider mechanical splices: very large bars, heavy congestion, perimeter beams with blast/continuity considerations. Mechanical splices are quick an inexpensive, but do require more time and cost than laps.

Welds should not be used unless you can be sure all of the requirements will be met, and the welding will be competently done in a manner equivalent to shop welds. Field welds should only be attempted on ASTM A706 reinforcing steel. Field welding will slow work and require new trades on the job (welders, weld inspectors).

John Turner CSP PE
CRSI Greater Southwestern Regional Manager

 

[vandede427]

do you work for BP?

 

[Zambo]

TXStructural,

when you say large bars what diameter are you considering? I would say 32mm diameter and 40mm diameter are still in the range where staggered lap splices are the preferred method if space is available.

I agree that in general mechanical couplers will be more expensive than laps. But of course they have their uses where required to overcome construction issues (lack of space, to be cast against formwork)

 

[johnthy]

Thank you very much everybody!

 

[TXStructural]

Laps of large bars often result in congestion problems and very long laps. These laps are frequently in beam-column intersections, making congestion worse, and resulting in conditions which easily result in poor consolidation of concrete.

From the CRSI Manual of Standard Practice (8.6.2 Lap Splices):
"Lap splices of #14 and #18 [#43 and #57] bars should not be used, except in compression only to #11 [#36] and smaller bars."

John Turner CSP PE
CRSI Greater Southwestern Regional Manager