Overturn Moment Calculations

[99491]

Dear All,

I know this subject has been discussed in great detail but I have one query. When calculating the overturning moment Mw (sect 5.11, 11th edit) I have used the calculation previously mentioned on in this forum of (Wind Horizontal Press) * (Height*Dia) * (Height/2) + (Uplift Wind Press)*(Roof Area)*(Radius). Now my question is that should the uplift pressure just be the external wind pressure on the tank or should it be the external pressure plus the internal pressure?

Any assistance would be greatly appreciated.

 

[JStephen]

The internal pressure is a separate factor in the equations, so it is not combined with the internal pressure from wind.