The form-finding process in RFEM searches for a shape that is in equilibrium with the boundary reactions. For members, this shape depends on the defined force or geometry parameters; for surfaces, it depends on the defined force parameters. If other force influences occur in addition to these object-related form-finding specifications – such as the self-weight of the objects themselves or the weight of cable node connections – these loads must be defined separately. There are several ways to consider additional loads that influence the form-finding. There is no universal, optimal method for this.
Defining the additional loads in the Form-Finding load case
The Form-Finding Load Case with the action category "Prestress" usually contains your Form-Finding Loads. It is already possible here to define other loads directly in the load case. For example, the self-weight can be considered with a factor, or loads can be defined to influence the form-finding.
Adding load cases to a Form-Finding load case
This is fundamentally the same option, but here you define the additional loads in one or more other load cases and then add them together with the Form-Finding load case to form a single load case. It is best to name this load case "Form" and apply it as the initial state for further combinations. The following webinar shows the procedure from minute 20 onwards.
Combining the load cases in a load combination
You can also use a load combination to generate the desired shape that is to be created based on your prestress and additional loads. The advantage of this method is that you can easily adjust the factors for the prestress in the load combination and thus influence the shape.
