CMU ties

[reverbz]

Hey guys,

I was wondering when you require ties in CMU piers/pilasters/columns . Is it anytime you're using any type of built up CMU column? I've seen pilasters with no ties called out but not sure how the line is being drawn. Is there a good rule of thumb for this? I have a client asking if they can avoid it for some small 16" square piers experiencing bearing only.

Thank you!

 

[XR250]

I have never needed them by the numbers nor have I ever seen them.
I am now also curious.

 

[TRAK.Structural]

For commercial work I have always used them as a standard practice, #3's in the bed joints at regular spacing.

For residential I don't require any. If it's a pilaster as part of a wall I would make them course it in or provide wire type joint reinforcing just to hold it all together, but not rebar.

 

[reverbz]

For commercial work I have always used them as a standard practice, #3's in the bed joints at regular spacing.

For residential I don't require any. If it's a pilaster as part of a wall I would make them course it in or provide wire type joint reinforcing just to hold it all together, but not rebar.

Thanks for the reply. When you say you make them course it in could you explain that a bit please?

 

[bIockhead]

I think no ties are fine if the bars are there for tension (bending) and not required to not buckle in compression. There are many cases where a pilaster (thicker built up section) does the job with bars and no ties, simply from the increase in effective cross section depth (moving the steel further away from the compression face).

If you are using the masonry, grout, AND bars for your axial load carrying capacity then you need to tie them.

Only the designer knows whether they need that steel or not. If you are counting on those bars in compression, then it needs to be tied.

 

[bIockhead]

Thanks for the reply. When you say you make them course it in could you explain that a bit please?

I'm guessing they are referring to ties that line up with the mortar joints between full units. Can interfere with unit placement if the bars are too big, and ideally (not always practically) are under half the thickness of the specified joint.

 

[TRAK.Structural]

Thanks for the reply. When you say you make them course it in could you explain that a bit please?

See below. Basically building the pilaster integrally with the wall by the way you stack the blocks.