Generate a snow load with surcharge

In SCIA Engineer, surface force free loads allow you to generate area loads different from the one uniformly distributed on a selected 2D entity.

This option can be used to generate snow loads with surcharge also called snow loads with drifted load arrangement or snow accumulation.

In the example below a snow load of 0.45 kN/m² is applied to a roof 12 m wide, but, on the sides, a surcharge is considered with a maximum load of 1.25 kN/m² on a strip 2 m wide.

Step 1 (suggested): move the workplane (User Coordinate System or UCS) to the top of the roof:

Step 2: apply the uniform load as a free load on the area from 2 m to 10 m from the eaves of the structure. Add a free surface load (Input panel > workstation Loads > category Surface loads) with as properties Distribution = Uniform, System = GCS and Location = Projection. You can either use the snapping points from the structure or from the dot grid to draw the load or you can work with coordinates as well of course.

Step 3: create the trapezoidal load, by using the desired parameters. Add again a free surface load, now with properties Distribution = Dir X (or Dir Y depending on how you want to define the non-uniform load), System = GCS, and Location = Projection. You can directly use the snapping point of the previous created free load. For the load on the other side of the roof you can use the mirror command (Main menu > Edit > Modify > Mirror).

Note: if you have other floors, make sure you generate the snow only on the roof (you can use either the property 'Validity' or the property 'Selection' in the properties of the free surface load: