Helical Tie in Concrete Column

[dcarr82775]

I can't find anything in ACI318 that prohibits this. In a tied concrete column, if ties would be provided at say 12"o.c. I would think it is acceptable to provide a #4 spiral with a 12" pitch. I would not be considering this a 'spiral' as is grossly violates those rules, so I think of it as a helical tie.

Anyone know of something that prohibits this use?

 

[ztengguy]

I dont get it. if you saying you would provide a spiral but call it helical it would be ok by code? whats the difference?

 

[dcarr82775]

Let me ask it differently. Anyone know of a reason a #4 spiral with a 12" pitch is not allowed as a substitute for #4 ties @12" spacing?

I was trying to clarify that for the purposes of the design strength, the column is considered tied. I would not use the 'spiral' axial strength

 

[UcfSE]

I can't think of anything prohibiting what you're proposing as long as you design it as tied, though I never specifically looked either. What's the benefit to doing this?

 

[ztengguy]

I think I get it now. I dont think you can argue its closed. sprials usually are closer spaced.

 

[ztengguy]

might be some help here.

http://www.utoronto.ca/sheikh/Sheik...amim A.Sheikh and Murat T.Toklucu) , 1993.pdf

 

[dcarr82775]

I wouldn't dream of considering it a spiral column, definitely tied.

As for why, the contractor asked if he could do it that way instead of using ties. No idea why

 

[dhengr]

Do the ties need a min. angle of bend at each vert. bar, to confine the vert. bars? Aren’t a 90̊ bend and a 135̊ hook o.k. as long as they alternate? Any confinement violation in that respect? How big is the dia. of the column? I can imagine these coming out to the job looking like a slinky, and then just being pulled up around the vert. rebars, and then just tied off. Although, the pitch spacing may be a bit tricky in the field; whereas a rectangular tie is spaced and tied at the corners and then tied off to the other verts. What’s the max length you can get #4 rebar? I can see a rebar faber. loving this; he’d just stuff 20 or 30' rebar lengths into a bender/roller, and run full length spirals (slinkies); no cutting or bending at exact locations.