The pressure that the roof sees is 101348 - 101325 Pa or 23 Pa. , assuming that the pressure under the roof is atmospheric.
Thank you David.
So when I get a wind analysis like this, I only need to substract the normal atmosferic pressure at sea level (101325 Pa), from the highest value of the pressure I got in the Solidworks analysis. Right? In this example, like you said, the highest pressure is 23 Pa.
But on the other hand, when I substract the minimum pressure (I got from Solidworks analysis) with normal atmosferic pressure at sea level (101325 Pa): 101290 - 101325 Pa = -35 Pa So this means I have suction, not only compression as a result of the wind load, right?
Then how can I apply this load to my grid (space frame) construction I already have in my structural engineering software (I am using RSTAB, although SAP 2000 could handle it too)?
Because of the "airfoil" like shape of your roof you certainly could have a suction or negetive load on your structure. Flow is computing the absolute pressure on the roof and ignoring the atmospheric pressure under the roof. Perhaps a means of netting this out would be to shell the structure in your model and place a "port" with a lid in a wall with a Boundary Condition that would be "environmental pressure". Then the values that you would be extracting from Flow should be actual roof load less the atmospheric pressure.
I am not sure, I understood you this part:
"to shell the structure in your model and place a "port" with a lid in a wall with a Boundary Condition that would be "environmental pressure"."
Can you be a bit more specific please?
About getting the actual wind pressure, rather then absolute pressure, I am trying to use this solution: making a new parameter that will automatically extract the noral atmosferic pressure (101 325 Pa) from my absolute pressure:
For now, I am having some problems with implementing that new parameter, as you can see in that topic.
But still, even in case I work out this, I still do not understand how would I then apply the results I got, to my grid (space frame construction) for that roof, I have in RSTAB or SAP2000?
Is this the way to do it:
So I will take the maximum compression (positive pressure) and maximum suction (negative pressure) and make two load cases with these values.
Correct? Or not?