Pad Mount Transformer Slab on Grade
Pad Mount Transformer Slab on Grade
(OP)
Hey,
I am working on designing a slab on grade for three pad mount transformers. The desire is to have all three on the same pad. Waiting on manufacture drawing to determine loading. Also requested any soil info we have.
I ordered an ACI 360 book to start. Should there be any other manuals I should consider?
I am thinking the pad won't be ro extensive. Possibly 4-6" with possibly WWF for crack control.
Any guidance would be appreciated.
I am working on designing a slab on grade for three pad mount transformers. The desire is to have all three on the same pad. Waiting on manufacture drawing to determine loading. Also requested any soil info we have.
I ordered an ACI 360 book to start. Should there be any other manuals I should consider?
I am thinking the pad won't be ro extensive. Possibly 4-6" with possibly WWF for crack control.
Any guidance would be appreciated.






RE: Pad Mount Transformer Slab on Grade
RE: Pad Mount Transformer Slab on Grade
The design is being done in the United States.
Thanks
RE: Pad Mount Transformer Slab on Grade
Also, transformers are heavy, for their size. The three transformers will not be set in place simultaneously - all it takes is a second or two of differential (structural) loading as they are put in place to crack an unreinforced (with WWF) slab.
I'm not saying to overdesign the pad, just take into account that the loading is not a predictable as the manufacturer's data may indicate. Properly compact the soil, make the pad a little thicker (say an additional 2" to 4", or so) than calculations indicate, and put an appropriate quantity of rebar in the pad.
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RE: Pad Mount Transformer Slab on Grade
SRE as an alternative I was thinking of designing as three separate pads with joints, but no reinforcing steel to join the pads. I believe this would avoid issues of unequal loading.
RE: Pad Mount Transformer Slab on Grade
Three transformers are probably not just three independent transformers but may be integrated components of one, 3-phase electrical circuit. There may, or may not, be a reason to have all three on one foundation (perhaps, ganged electrical switching).
Keep in mind that civil / structural is providing support (pun intended) to the electrical system. Civil designs that may be seem best in their own right, are actually not appropriate.
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RE: Pad Mount Transformer Slab on Grade
RE: Pad Mount Transformer Slab on Grade
IMHO, over time you will find that most of the projects we deal with need to exceed any (civil/structural) "code" in general use.
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RE: Pad Mount Transformer Slab on Grade
Currently I have a copy of ACI 360 on order and have a copy of Designing Floor Slabs On Grade, Ringo & Anderson.
RE: Pad Mount Transformer Slab on Grade
IMHO, a floor is large enough horizontally (compared to thickness) that it needs joints. Joints are where much of design work is concentrated. A modest sized foundation is typically monolithic. What is the approximate size of the pad(s) and weight of each transformer?
For floors, the Ringo - Anderson book is considered a classic reference - can't do better than that. Still, don't think of either this book or ACI 360 as "cookbooks". You will have to determine what criteria is important for your project to make a meaningful start.
I realize this may seem like trying to "lift yourself by your own bootstraps"... but this transformer pad is a great place to start. Has your boss assigned you a mentor, or is he/she able to help with technical advice?
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RE: Pad Mount Transformer Slab on Grade
RE: Pad Mount Transformer Slab on Grade
My plan so far was to use Ringo - Anderson and ACI 360 as a reference for determining the slab thickness and reinforcement. Also we have some standards for smaller transformer foundations.
I have not been assigned a mentor, might be a little while with the current work we have. I have been in touch with our station/generation side and have asked them for any suggestions. Definitely have the feeling of "lift yourself by your own bootstraps". Ha. But I do enjoy the challenge.
RE: Pad Mount Transformer Slab on Grade
Basics of Subgrade Preparation
Choosing Design Methods For Industrial Floor Slabs
Effect of Design Variables On Floor Thickness Requirements
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RE: Pad Mount Transformer Slab on Grade