I am trying to model a simple snow drift load as a rectangle (snow drift on a low roof against a wall with a higher roof) and tried making three points along each side of rectangle - first point for "Drift magnitude 1", second point for "Drift magnitude 2" and "Drift magnitude 3" to correlate to the triangular drift shape as shown in ASCE 7-10, Figure 7-8, page 34. That made sense to me, but when I run an Integrity/data check, I get an error that says I cannot have collinear points for the M1, M2 and M3 on my drift.
If I go to change the polygon, the "collinear points" error goes away if I do a non-rectangular shape. However, I also sometimes get an error about a "negative load" value. The only way I was able to clear the error was to change the polygon to a non-rectangular and irregular shape, which does not comply with the actual shape of the snow drift.
RAM Help (found by doing a search on "drift snow" just says this: "If a Drift snow load property was selected for this snow load, the Set Drift Magnitude Points dialog appears once the polygon is closed. Select 3 vertices of the snow load polygon to correspond to the 3 magnitude points. When the polygon definition is complete, the new snow load assignment will be made inside the defined polygon."
Please clarify how to set the polygon shape!