Wide Flange Column Embedment Into Pier Footing
Wide Flange Column Embedment Into Pier Footing
(OP)
Hello,
Need some help in figuring out the required embedment length of a wide flange column into a pier footing to fully develop axial and flexure load to the pier. Thanks
Need some help in figuring out the required embedment length of a wide flange column into a pier footing to fully develop axial and flexure load to the pier. Thanks






RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
To form a void in the footing drop the column in, level and plumb externally, and fill with grout.
To externally level and plumb the column with connectors, and then place the concrete.
I don't like either of them, all columns would have to be done simultaneously.
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Wide Flange Column Embedment Into Pier Footing
Sounds like others interpreted your situation differently.
The more info you give us the better help you will get!
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
The concrete is simply cover for the steel and an enlarged bearing surface against the soil. An oversized post socket.
Very quick and cheap, since the base plate and anchor bolts are eliminated. Okay for single, small monopoles.
However, not the appropriate solution if normal structural steel tolerances (horizontal and vertical control, plumb...) are expected.
Your drawings will need to be more specific about tolerances and be more involved in "means and methods" than usual.
RE: Wide Flange Column Embedment Into Pier Footing
I have seen lighting poles done in the manner described by ATSE, but they were concrete poles, not steel.
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
It is done sometimes but it does have its problems. When I have used this methods for small signs I have designed it as ATSE has suggested - with the concrete just acting as a cover.
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
Analysis is straightforward, with resolution of the moment (and shear) at the column insertion point and applying a triangular stress distribution on the grout block. Required depth of embedment can be computed algebraicly from an assumed stress block. You can mechanically anchor against pullout by inserting a dowel through a hole in the column or compute the shear-bond strength of the grout/column interface.
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
How did you design it?
Ron,
Can you expand some on how you design these? what do you mean when you say grout block? I guess I'm not visualizing this the stress distribution your describing.
Sorry don't mean to hijack the post.
EIT
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
Analysis is as samchrun noted.
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
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RE: Wide Flange Column Embedment Into Pier Footing
Michael.
Timing has a lot to do with the outcome of a rain dance.
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
I got a nice dose of Aluminum design this year because someone wanted to put a 12' sail (canopy) on their existing building. All I have to say is Weld affected this Weld affected that, can I have more strength, is there some way we can do this in steel.
It was a good learning experience though.
And although I was a little nervous about the design (being my first time and all) when I saw the manufactures product I thought - My support is designed for 40psf but that thing is going to fold like a deck of cards with 10psf.
EIT
RE: Wide Flange Column Embedment Into Pier Footing
RE: Wide Flange Column Embedment Into Pier Footing
I see no confining reinforcing in your pier. What happens when the concrete cracks between the steel column and the face of the pier? I have been doing similar designs for a solar installer here in the Northeast US. They do not want to look beyond the life of the subsidy that helped pay for the solar installation. We have yet to converge on a method that they like and that I can stand behind. Rust will be the downfall of the method you depict, and at some point in the life of the column it WILL crack the concrete surrounding the column. Confining reinforcing (column ties) in the pier is a must IMHO, no matter how you connect the steel column to the pier.
This must be an installtion in the lower latitudes. Here in my area the pivot point for the array is much higher so that the array angle suits the sun's position during the winter. Makes wind analysis much more interesting.
Ralph
Structures Consulting
Northeast USA
RE: Wide Flange Column Embedment Into Pier Footing
This is called a ground-set foundation and is very common for flagpoles. Page 14 of the Metal Flagpole Manual published by the National Association of Architectural Metal Manufacturers illustrates some generic dimensions for flagpoles up to 100 feet. We have found these suggestions to be very conservative.
Your configuration is no different from a Pole type of structure and the methods to design footings for these kinds of structures have been around for years. One of my references is Design Notes and Criteria Pole Type Buildings by H.J.Dengenkolb and Associates, San Francisco. (Published 1968).
I assume that you have a geotechnical report for the site and if conditions vary across the site, you will have various embedment depth requirements. One of your biggest problems will be having enough mass of the steel column and the footing itself from pulling out of the soil. Either you develop enough upward friction at the sides of the 24" pier or you add weight of some kind. This kind of a structure is going to have a lot of movement due to the complexities of your wind load, so I would require a cage of stirrups in the hole. I don't know what kind of fixity you have at the ground level. (Sketch shows asphalt?) If this is not used as the point of rotation, you then do have to be careful where you select the start of the passive pressure of the soil for your lateral pressures. (Get it in writing from the geotech!) The design calculations for this kind of footing is easily set up in a spreadsheet so that you can hand calc the solution and be able to play with the different possibilities – such as depth, diameters, passive and maximum pressures. You should also be checking the bearing pressure – 2 foot diameter of bearing plus whatever friction factor on the sides of the pier may not be enough. You might end up with a bearing cap at the top of the footing to take care of this and also provide enough additional mass if the "wing" of solar panels tries to fly away.
Specifying stud anchors on the side of the steel column is easily determined - we don't count on any friction between the concrete and the steel. There may be some other methods that are cheaper.
Others have already provided you with other good basic design information.
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