Maximum pedestal height and unspliced dowels

[humanengr]

Can someone point to a guide on how high dowels can extend above footing before they
should be terminated and spliced, if the pedestal height is beyond that limit?
This is from constructability view, not a design issue.

 

[r13]

If there is another bar to be splice with the dowel, then terminate the dowel for splice length. If no other bar, provide development length for tension. For both cases, I would add at least 1" for tolerance.

 

[humanengr]

Understood. I was just wondering if this a rule of thumb for how high the dowel projection should be.
If the pedestal is "short", the dowel will extend up from the footing to near top of pedestal.
If pedestal is, say 12 ft. high, the dowels should not project that high, but somewhere in between is a cut-off.

 

[r13]

You do understand what is the "development length", which is specified by code (ACI here), and the length can be different for the load in the pedestal - tension, or pure compression. You can make it rule of thumb, once you know the variables in determining the required length.

 

[KootK]

I don't go much higher than four to six feet projection. At some point, it's easier to slip a pre-tied cage over the dowels than to save the laps but have to place the ties around the as cast verticals. This is something that you could also leave to the discretion of your contractor by way of some clever detailing.

 

[HTURKAK]

I do not know a common rule on how high dowels can extend above footing before they are terminated and spliced. It depends on some factors ; pedestal height, anchor rod length ( if applicable ), congestion of reinforcement etc.. in past, i preferred reinf. cage without dowels to avoid splice and for economy ..

 

[BridgeSmith]

Several factors are at play in the constructability. There is the stability of the bars themselves, which is limited by the size of the bars. In bridge columns, we'll go as high as 15', but we're typically using #9 or larger bars. Clearance would be the second main consideration - is there room to get the other components into place with the bars extended?

Those considerations aside, it usually comes down to the economy - How much additional effort (and therefore expense) is involved to save a few dollars worth of reinforcement? Generally, it doesn't take much additional complexity to make it uneconomical to use unspliced bars.

Rod Smith, P.E., The artist formerly known as HotRod10

 

[HTURKAK]

This respond reminds me a video of collapse of rebar tower...

Link =

https://vimeo.com/89336924