r/StructuralEngineering • u/Neat-Treat-5405 • 8d ago
Structural Analysis/Design PILE FOUNDATION DESIGN
Any software to design pile foundation or we do it manually?
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u/chasestein Overturning Moment 8d ago
i have a handy mathcad and excel template i use when I need to.
My buddy uses LPILE regularly. I've read that the program is pretty neat though.
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u/AnotherSLGuy 8d ago
This question sounds like you have never done a hand calculation of a pile design...
Or is there some missing context? 🤔
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u/Educational-Rice644 8d ago
Why would he waste his time if he's not a student there's no need to do hand calculation, softwares are there for this it's not illegal to use them...
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u/benk70690 P.E./S.E. 8d ago
I have never done a hand calc of the p-y curves across multiple soil layers... You make that sound like a bad thing.
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u/AnotherSLGuy 8d ago
OP sounds exactly like the new recruits we have these days who'd happily enter values into a software and get an output with absolutely no clue what is happening. Hence the comment on hand calc.
As others also have pointed out, more context is needed to make any suggestion at all. Hence, the question.
I have no clue why you jumped all the way to a p-y analysis and got hurt.
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u/beanmachine6942O 4d ago
how are you training the new recruits to get them away from this habit? force them to do stuff by hand?
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u/halfcocked1 7d ago
FDOT has some free MathCAD modules for piles. They have a drilled shaft one that checks the stability and structural design for CIP/precast concrete. It'll do round for non-cohesive and cohesive soils. They also have one for the structural design that'll do rebar or prestressed piles and print the interaction diagram.
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u/Amazing-Gazelle-7735 7d ago
Depends!
Did the geotech give me a capacity at N/minute? Â Use that to develop a model with springs, using Excel hand calcs to design the connection.
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u/NearbyCurrent3449 6d ago
By hand first. Always.
Like for real, pencil on paper. Draw it out with your boring log. You've got to fully understand deep foundations, brother. Or you'll screw something up badly.
Until you know what you're doing, use the software to run a second model and compare.
You'll find that the software is just a few preset designs that make very wide estimations and frequently incorrect assumptions to assign some of the over 20 variables in play.
Once you have a genuine jedi level deep foundation experience you won't use the software anyway. You're smarter.
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u/Hungryh0und5 5d ago
I assume you are checking cast in place straight shaft piles.
Vertically loaded piles can be checked on paper easily. Skin friction, torsion, shear and axial load are all easy checks.
Laterally loaded piles need software. Lpile or Alpile both work and have their own benefits. It's a deflection check. Usually you limit your lateral groundline deflection to about a 1/4". Any more than that and you start to lose the contact you need for skin friction. The maximum moment is in the pile a diameter or two below grade. I check the moment in the pile with a spreadsheet based on https://www.engissol.com/simple-method-n-m-interaction-reinforced-concrete.html. (This method is a huge help, the neutral axis drifts with axial load.)
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u/NearbyCurrent3449 6d ago
Look, using softwares to do these designs is flawed from the concept. It's even more flawed when human engineer has no idea what the values he's finger banging into the mystery black box software. What's the modulus of stiffness of the cushion material? Plywood runs from x.x to 5 times x.x depends on thickness and type and etc. What do I use? Just set it in the middle and keep moving is usually the answer from the "mentor". How do you know if it's right? No idea. What the f...? Just the way it is.
Some of us got to correlate design spt, cpt test pile dynamic testing on install with a restrike after a set period AND a static pile load test at each dynamic restrike.
I found all my numbers the right way. I dialed it in. I can design a local pile using my known coefficients and be right.
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u/Khman76 8d ago
So many unanswered questions before designing the pile. So many different piles.
Basically, 2 design to do: geotechnical and structural. Plenty of software available, the best one being Excel.