The form-finding process in RFEM searches for a shape that is in equilibrium with the boundary reactions for the members depending on the defined force or geometry parameters, and for the surfaces depending on the defined force parameters.
If further force effects occur in addition to these element-related form finding properties, such as the self-weight of the elements or the weight of the cable node connections, it is necessary to define these loads.
There are several ways to consider the additional loads that affect the form-finding. However, there is no universal method that can be safely recommended.
Definition of Additional Loads in Form-Finding Load Case
A form-finding load case with the "Prestress" action category usually contains the form-finding loads. It is already possible to define other loads directly in the load case here. The self-weight with a factor can be taken into account, or you can define loads in order to influence the form-finding.
Adding Load Cases to Form-Finding Load Case
In principle, this is the same option, whereby you define the additional loads in one or more load cases and then add them to a load case with the form-finding load case. You can name this load case "Shape" and use it as the initial state for further combinations. The following webinar shows the procedure as of minute 20.
Combining Load Cases in Load Combination
You can also use a load combination to generate the desired shape, which should to be created based on the 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.
