Restraining the top of a top column when using SAFE
Restraining the top of a top column when using SAFE
(OP)
Hi Everybody,
What would be the appropriate restrain for the top of the column above slab when using SAFE? and Why?
Why is that the column below the slab is always fixed at the bottom, but we are not fixing the top of the column above slab.
Some of my colleagues only restrain the column in Rx and Ry. Some restrain the column in Ux and Uy as well.
I would appreciate if somebody can give me some explanation or advise of how to model the columns above slab, particularly what would be the appropriate way of restraining the top of the column.
Thank you for your time.
What would be the appropriate restrain for the top of the column above slab when using SAFE? and Why?
Why is that the column below the slab is always fixed at the bottom, but we are not fixing the top of the column above slab.
Some of my colleagues only restrain the column in Rx and Ry. Some restrain the column in Ux and Uy as well.
I would appreciate if somebody can give me some explanation or advise of how to model the columns above slab, particularly what would be the appropriate way of restraining the top of the column.
Thank you for your time.






RE: Restraining the top of a top column when using SAFE
RE: Restraining the top of a top column when using SAFE
The direct design method and modelling recommendations in ACI tend to steer one towards using full height columns above and below your slab with the far ends fixed for both. That's the most common approach from what I've seen. Bookowski's method will yield pretty much identical results.
My main concern with pinning the far ends of full height columns is that it may lead to an underestimation of punching shear moments.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Restraining the top of a top column when using SAFE
RE: Restraining the top of a top column when using SAFE
So would that be a mistake if the column above is made weightless (still accounting for stiffness) and is full height and is only restrained in Rx and Ry ( rotation) directions. Bottom column is fully fixed.
Do I have to always fix the columns or pin them at the top for the top columns?
RE: Restraining the top of a top column when using SAFE
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Restraining the top of a top column when using SAFE
If you're interested in obtaining average column reactions per floor, you can play some accounting tricks as Bookowski has suggested. Take care to ensure that those tricks don't muck up your other results however.
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.
RE: Restraining the top of a top column when using SAFE
RE: Restraining the top of a top column when using SAFE
The greatest trick that bond stress ever pulled was convincing the world it didn't exist.