Concrete pressure equation

[richthorpe13]

Hi, I am a civil engineer and I have been tasked with preparing a spreadsheet that will calculate the rate of rise of concrete pours at different temperatures that each give a maximum concrete pressure of 80 kN/sq.m. Obviously I can do this by trial and error, but if I change the target pressure to, say, 60kPa then I have to go through the whole list and manually change everything.

Below is the equation to calculate max pressure (Note ignore the "Dh" equation as that rarely applies. The variable I want to calculate each time is 'R'. At the moment that is manually adjusted until the desired concrete pressure is reached.

Any help greatly appreciated

 

[Deleted member 4993]

Hi, I am a civil engineer and I have been tasked with preparing a spreadsheet that will calculate the rate of rise of concrete pours at different temperatures that each give a maximum concrete pressure of 80 kN/sq.m. Obviously I can do this by trial and error, but if I change the target pressure to, say, 60kPa then I have to go through the whole list and manually change everything.

Below is the equation to calculate max pressure (Note ignore the "Dh" equation as that rarely applies. The variable I want to calculate each time is 'R'. At the moment that is manually adjusted until the desired concrete pressure is reached.

Any help greatly appreciated

View attachment 34336View attachment 34337

Have you tried "Goal Seek" function in MS_Excel?

 

[blamocur]

You can reduce this to a quadratic equation. I've done the first few transformations -- can you complete them?

[math]s = C_1\sqrt{R}[/math]
[math]{P_{max}} = D\left(s+C_2K\sqrt{H-s} \right)[/math]
[math]\frac{{P_{max}}}{D} = s + C_2K\sqrt {H-s}[/math]
[math]c_2^2 K^2\left (H-s\right) = \left(\frac{{P_{max}}}{D} - s \right)^2[/math]