Max. rebar spacing in masnory 1

[Lot2Learn]

I am designing an interior masonry wall for some lateral load and I have determined that I need very little rebar. Is there a maximum rebar spacing limitation in the code somewhere, because I would like to place the bars @ 72" oc but I have noticed that most engineers tend to place the bars not farther then 48".

 

[CTSeng]

Unreinforced often works fine for interior partition walls. May depend on local trends since 72" is allowed but contractors may question if 48" on center is the norm.

 

[JAE]

I wouldn't go 72" - I'd either try to go non-reinforced - or a minimal 48" o.c.

The MSJC (ACI 530,etc.) has a requirement that the maximum "flange" width in bending in a wall is limited by bar spacing, 72" or six 6) times the wall thickness.

With typical 8" thick wall, that would put your effective B at 6x8 = 48". So going beyond 48" you are not getting any additional flange width help. Not a huge deal but consider it.

Also, section 1.17 has numerous requirements for minimum reinforcement in various seismic conditions.

 

[Lot2Learn]

JAE, thanks for the info. I'll be noting this down and studying up on it. The wall in question is 4" cmu and is 10' tall, braced @ top. I know that 6" interior wall can span upto 14' without reinf but I am not sure about a 4" cmu wall.

 

[concretemasonry]

Suggest 6" block instead of 4" because many contractors will lay 6" cheaper than 4". As usual in masonry, the material cost is a fraction of the labor. - Especially true if it is an exposed wall.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.

 

[apsix]

Can you reinforce 4" CMU?

 

[JAE]

I don't think reinforcing 4" masonry is possible...or at least very difficult due to the limited cell space.

 

[concretemasonry]

They can be reinforced if the local manufacturers uses newer style mold configurations (from the last 30 years) that have been shown to perform as weel for structural applications. If not for structural applications the engineer may permit the use. - Not too common in the U.S. where the masonry engineering is not as creative as elsewhere.

I beleive a 6" wall is more practical for something non-bearing as this is and could be reinforced if desired.

Dick

Engineer and international traveler interested in construction techniques, problems and proper design.