Dowel lap length too short
Dowel lap length too short
(OP)
I have an issue on a job site where rebar dowels were fabricated too short, therefore not providing the required lap length with the vertical reinforcing. One situation occurs at a basement wall for the reinforcing at both faces, and another occurs at column piers (steel building with concrete piers on the footings). The testing agency inspecting the rebar missed that they were too short, and the footings have since been poured. So, I now need a fix prior to pouring the walls and piers to get the appropriate lap. Two solutions I thought of initially were to either provide mechanical splices for each of the rebars, or dowel and epoxy the vertical wall reinforcing into the footings. I think both are very expensive, and even though it's not my dollar, I still hate to propose such expensive fixes if not warrented. Any simple fix that I am missing?






RE: Dowel lap length too short
Either use mechanical couplers or drill and epoxy.
However, how short are the laps? 90% of what was required? If it is close, then it might be worth check your demand to see if the reduced strength provided by the shorter lap is still acceptable, using As,req/As,pro.
RE: Dowel lap length too short
RE: Dowel lap length too short
RE: Dowel lap length too short
RE: Dowel lap length too short
RE: Dowel lap length too short
RE: Dowel lap length too short
RE: Dowel lap length too short
I suggest the following:
1. Use mechanical joint coupling. They are available.
2. Consider, in lieu of lapping, to extend the vertical bar into the footing and epoxy it so it is developed.
Regards,
Lutfi
RE: Dowel lap length too short
Similar situation may apply with your piers. Is there any real lateral load being applied at the base of those steel columns (or moment?) If it's just vertical loads (and therefore no bending in the pier) then all you really need, potentially, is a compression lap, which is much smaller.
RE: Dowel lap length too short
I think there is a rational basis to potentially reduce it, but I don't believe ACI allows it and I, personally, wouldn't do it (depending on how close it is, obviously).
I think the reduction from the cb/Dtr factor solved his problem, though.
RE: Dowel lap length too short
Mike McCann
MMC Engineering
http://mmcengineering.tripod.com