The form-finding process displaces the FE nodes of membranes and cables in space until the previously defined prestress is in equilibrium with the boundary elements. The resulting shapes utilize the used material extremely efficiently and are unique in terms of the force applied. In addition to a multiply curved membrane roof geometry subjected to tension in 3D space, this algorithm allows you to also determine the optimum element arrangement of a vault subjected to compression.
The form-finding analysis is possible in RFEM by using the RF-FORM-FINDING add‑on module. The program seeks the optimum element arrangement for tension and pressure loaded objects. This new force-based geometry is available with the active prestress for further calculation and determination of a cutting pattern.
The RF‑FORM‑FINDING add‑on module can be activated in the ‘Edit Model - General Data’ window, ‘Options’ tab. By activating the module, a new RF‑FORM‑FINDING load case is created and an additional menu appears in the main program, allowing for the definition of prestress conditions for membrane and cable elements.
Section of drawing with top view (top) and section through roof (bottom, © FHS Ingeniería Estructural Ltda.)
With the activated option "Topology on form-finding shape" in the Project Navigator - Display, the model display is optimized based on the form-finding geometry. For example, the loads are displayed in relation to the deformed system.
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- How do I model a tent roof with two cone tips?
- I would like to calculate and design "temporary structures." What do I need for this?
- How is an inflatable object simulated in RFEM?
- I have already divided my membrane roof into individual surfaces. Can I quickly create a cutting pattern from these surfaces?
- How can I define a material allowance at the edge of a cutting pattern?
- I have modeled a structure made of outer and inner cables as well as membranes, and get a message about instability or the error message "Jacobi matrix is not positive definite" in the RF‑FORM‑FINDING add-on module. What should I do?
- Why does the FE mesh of my conical membrane look like angular after the form-finding?
- How to model a cable net structure in using the RF-FORM-FINDING add-on module?
Form-finding of tensile membrane and cable structures
Generation of cutting patterns for tensile membrane structures