How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
(OP)
Here I am confused with the ks value that is ks=p/s where P (kg/cm2) is contact pressure and S (mm) is Settlement.
what is the the ks unit, According to
((Apurba Tribedi ( the Code Writer for STAAD ) Software
Senior Product Manager
Bentley Systems Inc.
Yorba Linda, CA, US ))
this is a ratio and ks unit should be kN/m2/m
and as I read from some other books it's unit is (ks) kN/m3
Can any one help me?
what is the the ks unit, According to
((Apurba Tribedi ( the Code Writer for STAAD ) Software
Senior Product Manager
Bentley Systems Inc.
Yorba Linda, CA, US ))
this is a ratio and ks unit should be kN/m2/m
and as I read from some other books it's unit is (ks) kN/m3
Can any one help me?





RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
f-d
ípapß gordo ainÆt no madre flaca!
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
just like kN-m/m =/= kN
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
If ks is a discrete spring (like a single pile under vertical load), units are kN/mm (or kips/inch).
If ks is an area spring (like a spread footing under vertical load), units are kPa/mm or kN/m^2/m (or kips/in^2 per inch, or kips/in^3).
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
Usually many people assume the kn/m3 as density thought is correct numerically.
I think Kn/m2/m is more correct.
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
Which is the same as: pressure/L
Ks has by coincidence the same dimensions as density but it is not a density.
There is really no fixed value used in practice, softwares should have a conversion capability and when we evaluate Ks we should Always be aware that conversion can be very, very Tricky, I'm speaking out of personal experience, once I got it wrong by two orders of magnitude...
popular units in metrics are kg/cm3 which is the same as daN/cm3, also MN/m3is used
There are four orders of magnitude between kN/m3 and daN/cm3, if I'm not wrong
Popular units in America are pci and kcf as far as I've seen
www.mccoy.it
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
Basically, in structure analysis we could divide our elements into many nodes, and possibly during iterations with geotechnical engineer, the result (k) will not same for entire slab.
and I believe that subgrade modulus is also correlated strongly to the shape of the structure (behaviour) itself.
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
It would be reflected accurately if you could do loading test like that, but in case you make an underground structure like MRT station, it would be so much hassle to do that.
So far I think it is difficult to do it manually, but your explanation seems very good. have to try it once.
in case that your structure is quite uniform in shape, not significantly differ between width and length, it should be fine to use formula.
in practical we need to compute it using software, in which the first value we can take from vesic formula or else, then iterate between structural engineer and geotechnical engineer. Basically this process is to find the settlement like your proposal for manual calculation.
please see this paper if you are interested.
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
I was only to be sure which unit should I use so they can use it in their proper way.
Thank you for All. I m really appreciated.
I think I invest my time in the right forum.
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?
RE: How to calculate ks value ( modulus of sub-grade reaction ) and what its proper unit?