Description
Structural
- Mar 2, 2016
- 5
I've got a metal building we're looking at putting building columns on turn-down foundations. Frames are ~90' long with 24' bay spacings. We will have internal columns so outward thrust will not be a major component.
I'm worried about potential issues with the eccentric column on the foundation (column will be ~1' from edge of slab). My thought is to size the turndown thickened area at the column large enough to handle the eccentricity itself without having to rely on the connection to the building slab for rotational stability. Does this seem reasonable? I'm sure some amount of force/moment would enter the slab, but if the soil/thickened foundation element can take it without this connection it will be less likely to develop potential cracking issues.
I'm also curious for those who have designed these in the past; how are you doing your slab contraction joints? Cut to the columns through the thickened slabs (it would seem the cracks would want to run-around the thickened areas), or have the columns in the center of a contraction joint grid? I would normally isolate the column from the slab with an isolation diamond and joints cut to this point, but the monolithic nature of it has me questioning my typical joint arrangement.
I'm worried about potential issues with the eccentric column on the foundation (column will be ~1' from edge of slab). My thought is to size the turndown thickened area at the column large enough to handle the eccentricity itself without having to rely on the connection to the building slab for rotational stability. Does this seem reasonable? I'm sure some amount of force/moment would enter the slab, but if the soil/thickened foundation element can take it without this connection it will be less likely to develop potential cracking issues.
I'm also curious for those who have designed these in the past; how are you doing your slab contraction joints? Cut to the columns through the thickened slabs (it would seem the cracks would want to run-around the thickened areas), or have the columns in the center of a contraction joint grid? I would normally isolate the column from the slab with an isolation diamond and joints cut to this point, but the monolithic nature of it has me questioning my typical joint arrangement.