Compression dev. length -- precast to CIP connection
Compression dev. length -- precast to CIP connection
(OP)
I'm working on my first big precast job (parking garage), here's my situation:
A 24"x24" PC column needs to be supported on a 5'-0" CIP pilaster above the ramp at the 1st floor. It's supporting the entire building. I've designed the pilaster to be slightly oversized (40"x24") to avoid interference/crowding with the anchor bolts from the column and the pilaster reinforcement. I need a fair amount of compression steel in the pilaster to make it work (12-#9). My question is about compression development length.
Usually, I develop the compression steel into the column above, but this isn't possible for this condition, due to the precast column. I need the steel for compression immediately upon load transfer to the pilaster, so how do I ensure development of the compression reinforcement? Or do I even need to worry about developing the rebar at this interface if I provide confinement ties (which I am, anyway)? Developing the compression steel into the foundation is easy (and necessary). I'm just trying to think about the condition at the top. Would providing a Lenton Terminator, or similar mechanical device at the top of each bar be sufficient? Then, do I need to worry about the 2" of concrete between the Lenton anchor and the top of the pilaster? I'm out of ideas.
Thanks in advance.
A 24"x24" PC column needs to be supported on a 5'-0" CIP pilaster above the ramp at the 1st floor. It's supporting the entire building. I've designed the pilaster to be slightly oversized (40"x24") to avoid interference/crowding with the anchor bolts from the column and the pilaster reinforcement. I need a fair amount of compression steel in the pilaster to make it work (12-#9). My question is about compression development length.
Usually, I develop the compression steel into the column above, but this isn't possible for this condition, due to the precast column. I need the steel for compression immediately upon load transfer to the pilaster, so how do I ensure development of the compression reinforcement? Or do I even need to worry about developing the rebar at this interface if I provide confinement ties (which I am, anyway)? Developing the compression steel into the foundation is easy (and necessary). I'm just trying to think about the condition at the top. Would providing a Lenton Terminator, or similar mechanical device at the top of each bar be sufficient? Then, do I need to worry about the 2" of concrete between the Lenton anchor and the top of the pilaster? I'm out of ideas.
Thanks in advance.






RE: Compression dev. length -- precast to CIP connection
But if you have bending at the top then you will need to develop tension capacity.
I dont think that those lenton terminators were developed for compression, they could punnch through the cover concrete.
RE: Compression dev. length -- precast to CIP connection
RE: Compression dev. length -- precast to CIP connection
If you need to transfer moment at this interface, use NMB splices or similar.
Call your local precaster. They are very helpful and will lead you in the direction of their standard practice.