Advice for pier footing

Chris.B:



Regarding the pier foundation and column design I think that the design
concept that has the lower steel tube end buried in a foundation of
concrete is less than optimal.

I'll agree with you that the bolted flange connection offers several
advantages. Some of these you have mentioned.

Demountability for replacement of the tube.
Possible removal of the above ground part of the pier.
Adjustability and alignment of the tube for fixed position or wedge.
Upgradability. Other types of tube columns or mountings could be provided.

Similar applications may be seen in the base mountings for large overhead
highway traffic signs. The concrete foundation for the steel tube sign
support column often extends above grade only 10 to 20 cm, and bolts from 4
to 12 in number extend higher.

The telescope column mounting hot dipped galvanized mild steel or stainless
steel bolts may held together to establish a certain parallel alignment of
the bolts using an aligning fixture that may be made out of the same steel
plate that will later be welded to the steel tube column to form the bolt
flange plate. The bolts are bolted into holes in the plate with two nuts
below and one above the plate. The bolt-plate assembly may be buried in the
top of the foundation when the concrete is placed. The aligned J-bolt
anchors extend above the concrete, and they hold the plate above the
concrete. Cure the concrete during water saturation for 1 to 2 weeks.
Adjust the plate with a level. Leave the two lower nuts on each anchor
bolt, and remove the top nuts and plate.

Weld the plate to the pier steel tube column, and complete that assembly.

Fix the assembly onto the nuts on the anchor bolts and secure it with two
top nuts on each bolt. Adjust the vertical steel tube pier column to
vertical with a level and align the telescope. Tighten the nuts to the
proper amounts. Adjustments may be made as required.

That's more on that topic.

Ralph Hertle