Eccentrically loaded foundations

[rovi123c]

I have a few queries about the formulas used in designing eccentricity.

Firstly we establish ex, which is the distance to the revised centre of gravity...and then ex/A re written as 1/?
K the equals 1± 6/?. Am I correct in thinking that the 6 in this calculation formula is a constant? Also the figure ? does this have to be greater than 6 otherwise, 1- anything greater than 1, would result in a negative number and I assume this would indicate uplift.

Is this correct?

Thanks

 

[paddingtongreen]

Look at it from first principles, do not blindly use formulas.
If the eccentricity is greater than one sixth the length, then there is lift off until the the eccentricity is down to one sixth of the remaining contact length. Then, MC/I = P/A and the pressure at one end 2P/A and zero at the other end. If the eccentricity is less than one sixth the length, you are back to P/A ± MC/I.

Look up the "middle third" rule.

Michael.
"Science adjusts its views based on what's observed. Faith is the denial of observation so that belief can be preserved." ~ Tim Minchin