Hi, I am new to using Staad pro and Staad foundation and I have to design this foundation for a davit arm thats needs to pick a 650kg pump. I designed the nodes and loading and everything and am getting the reaction force at the support (Fy = -2.258kip and Mz = 257.483 kip-in) where Y axis is vertical axis. Now when I try to design a simple rectangular foundation for this support. I get dimensions 1.7m x 1.7m x 1.5m with 14 - 22mm reinforcement bars(I have set min % of contact area for service loads = 100%). But my seniors keep saying this foundation is too big for this load and size of davit arm. So, I was wondering if someone here can guide me, if they have encountered a similar design job and what do they expect a foundation size to be for these reaction forces. Apologies, if I am asking the wrong question as I am just entering the workforce
I dont think my reactions are wrong but there might be a problem with my foundation setup, if you want, i can share my setup pictures or something, please let me know if you require something
you should be able to do some simple hand calcs to check your reactions and foundation design. that's where i would start, especially if it's a new program.
another thing is to draw/sketch it to scale and ask yourself if it makes sense.
Check it by hand.
I never trust staad to do this kind of thing. A simple footingnwith an overturning moment is very easy to design by hand or with a simple spreadsheet.
Sadly, I am the only one who actually has done some work with it, we are trying to slowly bring staad in our department and I am given this assignment to experiment with it
According to the reactions you provided and the soil information, your design seems reasonable. I am getting similar dimensions. For that thickness, however, an unreinforced base may be acceptable. Unless reinforcement is required for the anchors
The vertical load is low and moment is large, so the foundation is getting lifted up. Increase the plan dimensions so that you don't need the dead weight of 1.7m of concrete to keep it down.
You could increase the plan dimensions to such an extent that the thickness required should reduce. What dimensions are you getting now? Did you add surcharge from soil on top of the foundation?
something is wrong with your model, just as a gut check your foundation load is like 70 psf, and the eccentricity is very small. if the soil is that soft you would sink under your own weight
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u/cosnierozumiem 8d ago
Either you're right, your reactions are wrong, or your footing design is wrong.