relationship between k values and allowable bearing pressure
relationship between k values and allowable bearing pressure
(OP)
any one know of a relationship between the allowable bearing pressure and the modulus of subgrade reaction (k) value? I have one reference but I theres a typo on the page as none of the units tie up or make sense.





RE: relationship between k values and allowable bearing pressure
If you have found a relastionship, I would expect it to be imperical with the input and output units specified and a "factor" making the units come out correct.
RE: relationship between k values and allowable bearing pressure
RE: relationship between k values and allowable bearing pressure
I am not sure about the relationship between "k" and bearing pressure. I did find the relationship between passive pressure and "k" for pile design.
If you are looking for this information, please look at the article in ASCE CIvil Engineering, May 1969, pp.65-66.
("Side Bearing Pier foundations": By: B.L.McCorkle)from his His table you could interpolate the bearing capacity of shallow foundation by using "N" value (Bearing capacity of soil versus "N").
RE: relationship between k values and allowable bearing pressure
RE: relationship between k values and allowable bearing pressure
RE: relationship between k values and allowable bearing pressure
I believe we should be careful not to mix apples with oranges.
Such would be the case if we mix problems of plasticity (bearing capacity)with problems of elasticity (settlements/distortions).
Bowles does indeed provide a formula relating Kw to beearing capacity, in this case mixing, strictly speaking, apples & oranges.
He also provides more sensible formuals relating edometric modulus, or Young modulus to Kw. Oranges stay with oranges.
When I'm asked the k values (wothout in situ tests) I always apply the definition,that is figure out the settlements, my final value being the ratio Applied Load/settlements
RE: relationship between k values and allowable bearing pressure
RE: relationship between k values and allowable bearing pressure
Sorry I have been dormant all this time. What I meant was that the design bearing pressure could have some connection with the subgrade modulus. The design bearing pressure for shallow foundations on sand, if the footing width is greater than 4 ft, is calculated based on allowable settlement (in most cases it could be 1 inch, once again this value could change based on the situation). The calculated design pressure divided by allowable settlement could then be related to the subgrade modulus. Concept of CBR can be explained in the same vein. But I do not want to start another issue for now. That is probably for another post in this forum. The definition of subgrade modulus is pressure/settlement. This is my take on this matter. All the correlations have limitations and one has to understand these limitations before using them.
RE: relationship between k values and allowable bearing pressure
RE: relationship between k values and allowable bearing pressure
Manual method I followed is
1) Assumed beam is a line element
2) Calculated column loads
3) find out upward UDL coming from soil according to its bearing capacity (soil udl has found equaling the vertical loads of columns & soil load)
4) Considering udl upward, column loads downwards
5) Then calculated the BM & SF along the beam
But I want to do this via SAB2000 (or SAFE or ETABS).
I have done below two methods
Analysis with both soil udl, column point loads & put column places as pin supports
Analysis with soil udl, neglecting column point loads , but keep column places as pin supports
My problem is
If I use 2nd method then the reactions coming from the supports should be equal to the column loads? But it's not happened?
Bending moment diagrams are differing. That means manual BM diagrams are not same with computer analysis methods..?
Thanks you very much,
Chandana
RE: relationship between k values and allowable bearing pressure
Incidently no one i have ever asked has given me an adequate explanation of how the method is ok giving the difference in column loads you describe, other than its good enough for 'insert well known authers name' its good enough for me.
RE: relationship between k values and allowable bearing pressure