Calculating Applied Loads for Pile Design

[Devanb]

Hello all,
I'm a structural engineer and so I don't often design the actual piles to support my builidngs, I do however get asked to provide reactions so the Geotechnical Engineer can design them. My question is how exactly are the applied loads to be calculated for desing of these piles based on Canadian design practices, I'm talking specifically the vertical loads applied to the piles.

I know that unfactored loads can be used and so until now we have been using the simple formula of P = aD + bL + cS +dW, where a = b = c = d = 1. However, on occasion the results of this formula is nearly equal to or greater than the factored loads, which doesnt seem right. Is there documentation somewhere that allows us to use combinations to reduce the live, snow and/or wind loads? Or are we in fact not being as over-conservative as I think?

Cheers,
Devan

 

[JedClampett]

I wouldn't waste any time trying to refine pile loads. I would figure out load per pile using your formula, add a fudge factor and round up to the nearest 10 tons.
With any subgrade design element, it's disastrous to be caught short. It's just too difficult to get more capacity once piles are in the ground. You'll sleep better if you're way conservative.

 

[a7x1984]

Agreed with Jed if YOU are designing the piles. If you're just passing along values to your geotech, just give your working loads - let them do the fudge-factoring.

In Russia building design you!