Metric and Imperial Units

The above formulas may be used with both imperial and metric units. As with all calculations care must be taken to keep consistent units throughout with examples of units which should be adopted listed below:

Notation

• B = width of foundation, ft or m
• I_B = Boussinesq stress co-efficient
• L = length of loaded area, ft or m
• M = maximum bending moment, kip.ft or kNm
• P = total concentrated load, kip or kN
• w = load per unit length, kip/ft or kN/m
• q = load per unit area, kip/ft² or kN/m²
• r = horizontal distance to point of interest from load, ft or m
• r = radius of loaded area, ft or m
• z = vertical distance from load to point of interest, ft or m
• α & β = angle of interest, degrees
• v = Poisson’s ratio
• ∆σ = stress increase at point of interest, kip/ft² or kPa