How to apply area and eccentric loads to a bridge deck?


I am trying to apply a Sofistik area load to a bridge deck surface in a Grasshopper script, but am not succeeding in making it work when running the Sofistik project.

Firstly I have the bridge axis represented as a structural line with the relevant information like bridge cross section, but it is not possible to apply an area load to a structural line, only a line load, which acts along the structural line. But since this is a bridge deck I would like to apply eccentric loads simulating f. ex. a truck driving on one side of the bridge deck, or distributed loads across the whole bridge deck surface. How does one achieve either of these things in Grasshopper with the functions available from the Sofistik Rhino interface?

I tried Axis definition (of bridge deck) → Interpolate solid (shows 3d of bridge deck) → DeBrep (splits the 3d brep into multiple surfaces) → ListItem (retrieve the top surface) → Structual area
And then send the structural area both to SofiMSHC (to register it as a structural item) and to the area input of Area Load. But I get the error down below.

To get quick affirmation of how the bridge reacts to different loads I use the Sofistik project function in Grasshopper which takes the structural elements and loads and displays the animation of the bridge displacement/behaviour.

I get this error in the protocol, and the project calculation stops.

+++++ error no. 2046 in program SL_IA_GL:AREA ; input line: 8
AREA-loading could not be processed, problems with the defined area or least square 1

Does anyone know how to apply area loads or eccentric loads to a bridge deck?

Trebru (103.8 KB)