Here is a very quick tip and trick for modelling dead loads from internal walls to your analysis programs. You will first need to ensure that you have the Load Take down tool added to Revit which can be download from Autodesk Exchange Apps
Once this is installed you will need to add your internal walls and make sure that these are structural and have an analytical model. In the image below I have created a filter to show these in Red.
You also need to add Boundary conditions for the slabs, walls and columns and set the fixity for these. You can then start the Load Take down tool from the Extensions Ribbon.
Click the Structural Analysis command and then you can see the linear loads on either the entire structure or just the stories where the loads are applied. These linear loads can then be added to the Revit model (A manual process at the moment).
The model can then be transferred to your Analysis application.