Apply SURFACE TRACTION load, projected along direction (snow, wind...)

[Sbrabra]

Hello,

I'm dealing with masonry vaults design and I'm trying to apply a distributed load on vault complex external surface, whose Z-PROJECTED magnitude is known in therms of kN/m^2.
The point is: how to define a surface load on a curved shell, knowing its PROJECTED magnitude in Z direction, as snow for example? (for those who are familiar with SAP2000 as well, it's like assigning a distributed load with "Direction = Z projected").

Abaqus permits to apply a "surface traction -> general" with reference to a specific direction, but this type of load caululates the resultant in this way:
- resultant in Z = total surface_area * user_defined_load_magnitude

but I'm looking for:
- resultant in Z direction = surface_area_PROJECTED_along_Z * user_defined_load_magnitude

Since it's a very common, frequent and practical way to apply loads (snow, wind, soil above structures...), I wonder if Abaqus permits this kind of input.

Thank you for your help.

PS: I'm using ver. 6.5-1