CSA A23.3-14 - 7.6.5.3 1

[GreenJug]

Hello, I'd like[sub] some help on the aforementioned CSA clause in the title of this post. I am confused with the last sentence of the clause. The clause relates to ties in concrete compression members (columns) and the maximum distance of the final top tie from the slab/drop panel at the top of a column and, similarly, the maximum distance of the first tie from the bottom slab/footing.[/sub]

"Ties shall be located not more than one-half of a tie spacing above the slab or footing and shall be spaced as specified in Clause 7.6.5.2 to not more than one-half of a tie spacing below the lowest reinforcement in the slab or drop panel above. Where a slab is not continuous beyond one or more faces of the column, the ties that engage the vertical steel on any face not confined by a slab shall continue within the depth of the slab. "

What is the final sentence in this clause referring to? Is it requiring the reinforcement to change trajectory by 90 degrees and penetrate the slab?

Something visual to help my understanding would also be greatly appreciated! Thanks

 

[ggcdn]

If you have an edge or corner column where the column is truly at the edge of the slab (no overhang beyond the column) then this says to provide ties through the depth of the slab.

Without confining effects of the slab on all sides of the column, there is increased potential for bar buckling on the faces without slab, unless ties are provided.

-JA (working on [link calcs.app]Calcs.app[/url])

 

[GreenJug]

Hi ggcdn,

Thanks very much for your response. That certainly makes sense. So the tie is supposed to go through the slab and run parallel to the surface of the slab if i understand correctly? But I find it odd that it does not mention what length of tie should go through the slab. Should the tie only be touching the slab or should it go through 50 mm? 100 mm? I find it odd that it is not specified. Any opinions or insight on this?

 

[jayrod12]

It doesn't need the tie to extend into the slab directly, because the intent of the sentence is that where the slab doesn't extend beyond the column. If you mean on the 1, 2 or 3 sides where slab remains, It would need to be extended enough to be considered developed/anchored.