Pier/footing design

[dmoench01]

Hello,

This seems like a dumb question to me but I'm trying to minimize the reinforcing in this pier beam design. The government client has set the parameters of what you see in the attached section I've drawn. There will be a rigid frame column sitting on this beam and I've included the worst load combination for thrust at the top of this beam. I understand how to check stability against overturning. I understand that the beam is being twisted to the left thus producing tension in the right face etc. I typically design true piers to spread footings and this is a hybrid for me and want to make sure I'm attacking it correctly. There is no soils report but I'm assuming 2000psf allowable bearing. Also not sure how minimum steel requirements per ACI affect this structural element? So, in summary, how would you design this member?

Thanks,

Dwayne

 

[jimstructures]

KootK,

Do you mean the Butler/Computerized Structural Design, Inc. developed "Foundation Design and Construction Manual 2ed" from 1983/1984 or the Butler "Architectural & Engineering Manual" (much more recent but less engineering and more architectural) developed from the older "Product Reference Manual".

Jim H

 

[dmoench01]

Spats-

Actually our salesman finds projects like this to bid, in addition to the non-bid market we service. Most often these bids are building only but this was a foundation and building together as a bid package. Our salesman didn't dictate anything regarding the footing, it is just the approved DOT section they want to use. My final result was to redesign this section so it is workable and hope the DOT recognizes the shortcomings of their foundation section when everyone submits their bids. Our salesman is the point man on the project thus my reporting to him on the problem. Historically when we do things like this there is always at least one engineer involved on the DOT side. Whether they choose to take our suggestions, we will find out.

 

[KootK]

Jim,

The Computerized Structural Design one from the 80's is what I had in mind. In 2004, someone emailed me a scan of an old fax. It contained eight, very useful, pages of the manual. Based on the page numbers, it appears that there are at least 66 pages out there somewhere to be had.

Like SlideRuleEra, I'm a bit of a curator of antiquated structural engineering reference material. The Butler Foundation manual has been on my bucket list for a long time. If you know how I might obtain a copy somehow, I would be grateful to hear about it.

KootK



The greatest trick that bond stress ever pulled was convincing the world it didn't exist.

 

[spats]

Sorry dmoench01... I thought you might be talking about DOT's salesman.

KootK & jimstructures: Regarding your little side discussion, I have a copy of "Foundation Design and Construction Manual", but it's the first edition. I was with Butler in the 70's, and got to meet with Jim Fisher when he was working on the manual... a little trip on the wayback machine.

 

[jimstructures]

KootK,

About 125 to 130 double sided 8 1/2 x 11 pages. I do not have a scanned copy. 250 to 260 separate page sides in all.

We really need to move this to a separate thread.

Jim H

 

[BAretired]

If this is a salt storage shed, there will be lateral forces from the salt storage occurring above the floor.
[li]Are the precast panels acting as retaining walls to contain the salt?[/li]
[li]If so, are the panels relying on passive pressure from the earth outside the precast panels?[/li]
[li]If not, what is the purpose of the precast panels?[/li]
[li]Are the precast panels tied to the 12" slab?[/li] [li]What is the bulge at the bottom of the precast panels?[/li]
[li]How do the precast panels terminate at the bottom?[/li]
[li]Is there a concrete slab or footing under the precast panels?
[/li]
The overall concept is not clear.

BA

 

[spats]

Good observations BA. The rest of us are getting lost in our own side thoughts.

 

[dmoench01]

To BAretired

If this is a salt storage shed, there will be lateral forces from the salt storage occurring above the floor. yes absolutely, the panel projects another 12' above the floor
•Are the precast panels acting as retaining walls to contain the salt? yes
•If so, are the panels relying on passive pressure from the earth outside the precast panels? Normally when I see panels like this they are not embedded in the ground, they are completely above ground. They are self-stabilizing. Because this one is below ground it can't help but put surcharge load behind it because I know when they compact the soil behind the wall the loads will transfer through.
•If not, what is the purpose of the precast panels? see previous
•Are the precast panels tied to the 12" slab? no
•What is the bulge at the bottom of the precast panels? Not sure what you mean here.
•How do the precast panels terminate at the bottom? These are standard L or T interlocking panels you see in these types of buildings and grain or fertilizer storage facilities as well. They have a flat bottom.
•Is there a concrete slab or footing under the precast panels? No, whether above or below grade, most often these type panels sit on grade and a poured slab is placed around them so there is no lip inside the building to catch the loader bucket on.


The overall concept is not clear.

I pulled this from a standard DOT detail for which they have dozens of these buildings. I understand what they are trying to accomplish, it just doesn't work at all on paper, thus I've proposed a different detail.