A virtual work or optimization operation requires the application of fictitious load(s) in the direction of the displacement under investigation. Such fictitious loads are grouped in the RAM Structural System as "Virtual Load" Cases. Both nodal loads and story loads are available in the Virtual Load cases. The nodal virtual load cases are defined in the Modeler while the story virtual load cases are defined in RAM Frame Analysis – Load Cases Mode.

The nodal virtual load cases are created just like any other nodal load case as described in the RAM Modeler manual.

Virtual story loads are created in RAM Frame using the Loads – Load Cases command while in Analysis – Load Cases Mode. Virtual loads have their own type: "Virtual Load". The loads are entered by specifying their magnitude, their direction and point of application.

The magnitude of the virtual load is not an absolute number. A load of any magnitude is theoretically possible. The only practical requirement is that the load be of a magnitude that produces reasonable (not very high or very low) participation factors (PF). The participation factor of an element is defined as the measure of a member’s contribution to the quantity under investigation, such as roof displacement. A good rule of thumb is to pick the magnitude as somewhere between 20 to 50% of the estimated seismic or wind load base shear in the building.

The direction of the virtual load should be in the direction of the drift under investigation. For example, for studying the behavior of the building in the global X-direction, both the "virtual" and "real" (wind, seismic or other) load case should be oriented along the global X-Axis. For studying the rotational characteristics of a building, the user should enter a small virtual load at a large eccentricity. This will essentially produce virtually a twisting moment that can be paired with the real load that is producing rotations in the building.

After both the real and virtual load cases are created and defined, they should be included in the list of load cases that are to be analyzed using the Process – Analyze command in Analysis – Load Cases Mode.