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Subgrade reaction coefficient for piles using japanese design code for building foundations

Subgrade reaction coefficient for piles using japanese design code for building foundations

(OP)
Hi All,

I am using LPile to derive p-y curves for a pile. I am also cross checking these springs using an empirical method, which I think is based on the "Japanese design code for building foundations, (AIJ, 2001)" - unfortunately this is only available in japanese.

The empirical equation I am using is based on the SPT N value and the pile diameter:
kc = 56 x N x (100 x D0)^-3/4

Unfortunately the empirical method is giving me a much different pile spring to the one I obtain using Lpile. I have tried to research the basis of the empirical equation to see if I could determine why the results would be so much different, however have not had much luck (with it being in Japanese).

Any chance anyone else is familiar with this? I am using the Reece method to determine springs in Lpile,

Thanks,

RE: Subgrade reaction coefficient for piles using japanese design code for building foundations

Why not just use another english/US based method to check? Also, I would trust Lpile far more than a japanese design code. Not saying that it would not be correct, but Lpile (and the methods employed) are industry standard now.

RE: Subgrade reaction coefficient for piles using japanese design code for building foundations

What is the kc value? and what is the restraint at the top of the pile. The latter value has a real impact on the output.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

RE: Subgrade reaction coefficient for piles using japanese design code for building foundations

(OP)
Hi CovertShear - the code is listed here: https://www.aij.or.jp/eng/publish/wwwpub.htm (7th one down in the structural engineering section) - I don't have a soft copy sorry.

EireChch - this approach is referenced in a New Zealand based code/report (Research Report 553) - I use Lpile also, was trying to see why the difference in springs using this method and Lpile would be so different - more for my own learning.

Dik - at the moment, we are modelling both piles with a free head - but I'm not sure what fixitiy the Japanese Code is assuming. kc gets multiplied by pile diameter and spring spacing (vertical spacing in model) to obtain the soil spring softness.

Thanks All

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