Embedment / fixity
Embedment / fixity
(OP)
I'm reviewing another engineers calculations,
They are Analyzing 11foot tall concrete columns/piers that are attached to 1 foot thick shallow foundations 3 feet below the surface of 110pcf soil (detailed soil properties are not provided), so the column projects 8 above the ground surface. The column has a significant later load at the top, and the engineer is take the column as fully fixed right at the surface of the soil, so they are analyzing as an 8 foot cantilever.
To me this seems a little generous, I'd rather see the bending moment taken at the connection to the footing, for the full 11 foot length , am I being too conservative?
Any thoughts would appreciated.
They are Analyzing 11foot tall concrete columns/piers that are attached to 1 foot thick shallow foundations 3 feet below the surface of 110pcf soil (detailed soil properties are not provided), so the column projects 8 above the ground surface. The column has a significant later load at the top, and the engineer is take the column as fully fixed right at the surface of the soil, so they are analyzing as an 8 foot cantilever.
To me this seems a little generous, I'd rather see the bending moment taken at the connection to the footing, for the full 11 foot length , am I being too conservative?
Any thoughts would appreciated.
M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)






RE: Embedment / fixity
RE: Embedment / fixity
If it were a continuous wall, would it be common to take the fixity at the ground surface for out of plane bending?
I've not encountered this construction before.
M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)
RE: Embedment / fixity
When it freezes it will expand - then shrink away from the column over time in cycles. The compaction and ability to develop passive pressure is questionable.
RE: Embedment / fixity
M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)
RE: Embedment / fixity
If it was necessary to reduce the load (for whatever reason), it could probably be modeled with soil springs over the bottom 3 ft. But even this is less than conservative, for the reasons JAE mentions. I'd avoid it if at all possible.
Brian C Potter, PE
http://simplesupports.wordpress.com
RE: Embedment / fixity
Mike McCann
MMC Engineering
RE: Embedment / fixity
M.S. Structural Engineering
Licensed Structural Engineer and Licensed Professional Engineer (Illinois)
RE: Embedment / fixity
RE: Embedment / fixity
RE: Embedment / fixity