Thru bolts in existing concrete column
Thru bolts in existing concrete column
(OP)
Hello all I am looking for some guidance on thru bolts in an existing concrete column (see attached pdf for clarification.)
I have pretty high loads when factored around 350 kips to be exact and using 1 1/2" bolts in double shear I can get the bolts to work for the shear. However, right now I am looking at Appendix D with my current cover and I am having all kinds of trouble getting it to work.
Has anyone else run into a situation similar to this? Any help would be greatly appreciated.
Thanks
I have pretty high loads when factored around 350 kips to be exact and using 1 1/2" bolts in double shear I can get the bolts to work for the shear. However, right now I am looking at Appendix D with my current cover and I am having all kinds of trouble getting it to work.
Has anyone else run into a situation similar to this? Any help would be greatly appreciated.
Thanks






RE: Thru bolts in existing concrete column
RE: Thru bolts in existing concrete column
RE: Thru bolts in existing concrete column
123 kips / 8 bolts = 15.4 kips single shear left side.
Assuming bolts are securely tightened, you will have confinement of the cover concrete around the holes. Which could enhance the bearing strength of the bolt against the concrete at the bottom.
I think slick's suggestion of epoxy in the holes before attaching plates is a good idea, assuming it has the appropriate compressive strength and will not flow under extended high load.
Ralph
Structures Consulting
Northeast USA
RE: Thru bolts in existing concrete column
How can you develop the full shear capacity of the bolts?
What mechanism allows the load to transfer from the bolt into the column?
I did a real basic bearing check that i think shows the bending of the bolt will be exceeded before the full 15 kips will be able to transfer into the column. (See attached)
Is there something in the concrete code that allows this connection to work?
As a note I have (very) limited experiance with steel to concrete connections. but quite a bit with steel to steel.
RE: Thru bolts in existing concrete column
If you can get epoxy to fill the opening so much the better. I have required it in the past but not so comfortable that the contractor will take the proper steps required to completely fill the void.
RE: Thru bolts in existing concrete column
RE: Thru bolts in existing concrete column
slta - I know where the vertical/horizontal reinf in the columns is and as long as it was built somewhat close to the existing drawings it shouldn't be a problem.
port/ron - I hadn't check bearing yet but what is your thought process that the bolt only bears 1-1.5"?
RE: Thru bolts in existing concrete column