The time-dependent stress losses from creeping, shrinkage, and relaxation have to be considered when designing prestressed concrete components. The consideration of relaxation losses when designing prestressed concrete in RF-TENDON and RF-TENDON Design is discussed in detail in the following text.
The efficient design of prestressed structural components requires a few additional steps that go beyond the standard reinforced concrete design, from modeling tendons to the calculation of equivalent loads to the cross-section resistance design. Therefore, it is important that the software for prestressed concrete design is structured and the navigation is possible in the program. RFEM with two add-on modules RF-TENDON and RF-TENDON Design fulfills these requirements and allows engineers to carry out the complete design of prestressed beams, frames, plates, buildings and bridges according to EN 1992-1-1 with National Annexes and SIA 262.
Once you have determined the final tendon geometry in RF‑TENDON, exporting the model to a CAD program can be useful. For this purpose, the module includes the option to export the file in the .dxf file format. You can select the export function by right-clicking the workspace. After selecting the DXF format and the storage location, additional settings can be made.
In RF‑TENDON and RF‑TENDON Design, you can review and adjust the code‑dependent factors, calculation parameters, and calculation methods using the "Code" button. You can display the settings and adjustment options according to a chapter of a code, selecting the "Grouping" option in the dialog box.
The equivalent loads determined in RF-TENDON due to prestress are transferred in RFEM as member loads or as line loads. A member load is used for member types with their own stiffness; a line load is used for member types without their own stiffness. In order to understand which values of the concentrated loads are to be transferred from RF‑TENDON to RFEM, you should use the following display settings: ~ Reference of the loads to the global coordinate system (GCS), ~ Load display: "Point"
With program version RFEM 5.06, you can edit several tendons in the RF‑TENDON add‑on module simultaneously. To do this, it is necessary to select the corresponding tendons in the tendon arrangement table.