Cast in Place Pier Construction/Design
Cast in Place Pier Construction/Design
(OP)
The ACI code provides for 3 inches of concrete cover when permanently exposed to earth for the construction of a drilled shaft pier. I would think it would be easier to have the rebar cage rest at the bottom of the pier for the purposes of construction. I am unaware of how the rebar cage supported otherwise during construction. I had been told once that the the purpose of the code was to prohibit corrosion of the steel, which requires moisture and air, and at the bottom of the pier there would be a minimum amount of corrosive action. I have seen piers designed in both ways(having the longitudnal steel extend to the end of the pier and detailed 3 inches short of the pier base) and I am looking for some clarification as to the preferred or proper design.






RE: Cast in Place Pier Construction/Design
RE: Cast in Place Pier Construction/Design
RE: Cast in Place Pier Construction/Design
A crane usually is holding the cage in place until enough concrete is poured and the cage is in place securely. I recommend a minimum of 4" clearance laterally. I have seen guys trying to hold the the cage in position laterally with 2 x 4's wedged between the cage and the casing. Sometimes the cage will shift as the casing is pulled.
RE: Cast in Place Pier Construction/Design
In addition to the plastic chair supports, it is also a common practice to hang the cage from the slots at the top of the temporary casing at the ground surface until the concrete has been poured. No need to monopolize the service crane for holding the cage in this case.
Jeff
Jeffrey T. Donville, PE
TTL Associates, Inc.
www.ttlassoc.com
RE: Cast in Place Pier Construction/Design