Hello,
I am trying to verify the calculation sheet I have obtained from STAAD Foundation. Based on my hand calculation, the net corner pressures of the isolated footing is 213.28KPa. However, the software computed it to be 216.882 (see attached PDF file). My hand calculation solution is shown below:
Length = Width = 4.05m
Axial load for Loading Combination #3 = 3500kN
Pressure = 3500kN / (4.05m)^2 = 213.28kPa
Why is there a discrepancy? Is there something wrong with my software settings or hand calculation?
Query on Net Pressure - Isolated Footing.pdf
We need the SFA file.
Here's the SFA file
Isolated Footing - Axial.sfa
Compute the Gross pressure
Pressure due to column load = 3500 / (4.055 * 4.055) = 212.9087 kN/m2Pressure due to selfweight of footing = 0.9 * 23 = 20.7 kN/m2Pressure due to soil weight = 1.0 * 19 = 19 kN/m2Pressure due to surcharge = 0.0
Gross pressure = Sum of the above = 252.6087 kN/m2
Compute the Net pressure
Net pressure = Gross pressure - (Gamma * H)
where Gamma = Unit weight of soilH = Height of soil above bottom of footing
Gamma * H = 19 * 1.9 = 36.1 kN/m2
Hence, Net pressure = 252.6087 - 36.1 = 216.5 kN/m2
Answer Verified By: Louis Flores