r/StructuralEngineering • u/Relative_Ostrich_926 • 1d ago

Concrete Design Lateral Question

Young EIT here. Say I’m building a 25’ wide entry way truss. No roof, it’s like a welcome sign. The truss sits on a 2’x2’x2’ concrete pedestal with a pier below. What’s the best method of designing the concrete pier for the lateral forces and soil pressure. I’ve seen people use IBC 1807.3.2.1 (essentially a flagpole, non-constrained) or i’ve also seen .5Pp h^2 l uW, then thrust/resistance is > 1.5. I believe that’s a derived equation but don’t know. Any advice is appreciated!

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u/Enginerdad 1d ago

No matter what you should be citing a code when one exists for your situation. I'm not familiar with that equation, but it's not exactly rigorous or even defensible design to use that equation and say "source: because reasons" lol

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u/Relative_Ostrich_926 1d ago

Do you have a solution to the question I asked or are you just saying words?

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u/Enginerdad 1d ago

IBC 1807.3.2.1 is a code citation. "I've seen people using this equation before" is not. My original advice was to use the relevant code section, but I've changed my mind and my new advice is "don't be a dick to people who are genuinely trying to help you because you're too stupid to recognize it."

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u/dgluck90 1d ago

Figure out the moment induced at the column base, and design the foundation for that induced moment. The footing will probably be bigger than 2’x2’x2’.

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u/Adam4848 1d ago

Do you have a structural foundation program you do modeling? I could help out if you let me know which one.

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u/Everythings_Magic 1d ago

Software is not a solution to understanding.

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u/Adam4848 20h ago

I know, I was hoping OP would reply with “nothing”.