How to load the frame beams with mass (weight of the roof), that look realistic?
It's quite simple, really. All parts must have their respective materials properly assigned. Then, you must use the "Ground" tool while in the "Structural Analysis" simulation tool. Ground the face opposite of where the force will be applied. Next, select force. Apply this on the face opposite of the grounded face. I then would recommend doing what Mr. Rinaldi recommended, and input force in that manner. Or, simply use the lb. unit when inputting force.
Hi friend! I sometimes use the frame analysis and I don't find a tool to input a mass of structure. But you can transform the mass to force. Force = mass * acceleration of earth. I hope I was helpfull.