Urgent - Concrete Beam to Column Connection
Urgent - Concrete Beam to Column Connection
(OP)
I am designing a 9 story concrete structure that employs a two way slab system supported by 16" sq. columns. At the second floor level a column is being supported by a reinforced concrete transfer beam that is 16"X42". I designed the beam as simply supported and the columns supporting the beam are non-slender and I have the required capacity per ACI318-89 (Code referenced in the current building code) The column that supports the end of the transfer beam terminates at the base of the beam. I am racking my brain to figure out the best way to connect the transfer beam to the column to have it remain a simply suppoted connection and not have eccentricity on the column. Could any of you give me some advice?






RE: Urgent - Concrete Beam to Column Connection
Why cannot there be continuity of the beam with the column to help control the eccentricity?
Something is missing here. Transfer beams are not uncommon and really not a stresser. Please fill us in further.
Mike McCann
MMC Engineering
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
That would assume that the beam to column has a fixed support. The beam was designed as simply supported so the moment at the columns is zero unless the connection that is detailed has rigidity. From what I understand from the code is that the equations checking the axial capacity of a non slender column take into accound a small eccentricity. Is this sufficient?
RE: Urgent - Concrete Beam to Column Connection
Had you not accounted for this load difference? Is the transfer beam a last-minute change from the Architect? If possible, I would try to compensate for the ECC with extra top steel in the beam over the column at this point, or increase the column steel if still possible. Assuming a pinned base for the columns, the doweling should still be OK. If not, there is a problem.
Mike McCann
MMC Engineering
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
"There is no differential loading as the transfer beam is on one side of the column only and bears fully across the top of the column."
Now I am confused here. Sorry for that. I thought that the transfer beam was supported by a column at each end, which is normal.
Is there a way to post a sketch here as what the situation is? At least it would help me.
Mike McCann
MMC Engineering
RE: Urgent - Concrete Beam to Column Connection
Mike McCann
MMC Engineering
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
That said, if you modeled the beam and columns together, and correctly accounted for relative stiffness, the amount of moment sent into the columns might be minimial as the beam would be stiffer, not deflect all that much and thus not rotate at its ends.
If you try to create some sort of gap, or hinged joint to mimic a pinned end, you might induce MORE moment into the columns if the rotation creates any kind of eccentricity on the load applied at the top of the column.
For a major transfer girder/column arrangement, with no other redundancy in the system, I'd be pretty careful about designing this without following the full load path through.
RE: Urgent - Concrete Beam to Column Connection
BA
RE: Urgent - Concrete Beam to Column Connection
RE: Urgent - Concrete Beam to Column Connection
The project is moving so fast and they are building the structure now and will be pouring concrete in the next few days so I just want to make sure that I have all my bases covered thats all. I guess I just went into freak mode and didnt really just sit back and make sense of it all.
Thanks again for all your help!!!!
RE: Urgent - Concrete Beam to Column Connection
Thanks for explaining what I wanted to say, but didn't. I was trying to point STEVE97 in that direction, but I did not explain myself!