In the Cross-Sections table of the 'Timber Design' category, all cross-sections that you have created in the model are listed.
Valid Cross-Sections
The timber design of member cross-sections is coordinated with the Standard. You can recognize whether a cross-section is valid and also relevant for the design by its font color. The colors mean:
- black: Cross-section is suitable for the design and is used for the objects to be designed
- red: Cross-section is not suitable for timber design
- blue: Cross-section is not used in the model
- gray: Cross-section is not used for the objects to be designed
For timber design – depending on the standard – cross-sections of the Thick-walled I categories, the types
and
of the Parameterized category, as well as
of the Built-up category are valid. Cross-sections of the cross-section properties program RSECTION can also be designed, provided that the calculation is carried out by the finite element analysis.
All cross-sections must be assigned a material of the Timber type.
The categories of the individual cross-sections are specified in the 'Cross-Section Type' table column.
Objects with an invalid cross-section are not considered in the design – even if the 'To Design' option is activated for this cross-section. They are automatically classified as 'Not valid / deactivated' in the Objects to Design table.
Removing Cross-Section from Design
For a valid cross-section, you can exclude all objects to which the cross-section is assigned from the design by deactivating the 'To Design' check box. As a result, these objects are classified as 'Not valid / deactivated' in the Objects to Design table and are not examined in the design.
Adjusting Cross-Section
If necessary, you can adjust the properties of a cross-section in the editing dialog. To do this, double-click the row of the cross-section or click the
button in the table toolbar.
In the 'Options' table column, icons for presets or modified values are displayed (see image 'Cross-Sections' table). They allow a quick overview of the used cross-sections. The
icon, for example, is assigned to a rotated cross-section.
Using Different Cross-Section for Design
You can use a different cross-section for the design than for RFEM/RSTAB calculation: To do this, click into the corresponding row of the 'Use Different Cross-Section for Design' table column. Using the
button, you can then import a cross-section from the library.
If a different cross-section is stored in the column, further options are available in the context menu. This allows you to transfer the new cross-section to RFEM or RSTAB so that it is also used in the structural analysis. It is also possible to import the original cross-section back into the table.
Optimizing Cross-Section
The Timber Design add-on offers the possibility to optimize standard cross-sections. In this simplified optimization, the program searches for the smallest possible cross-section within the same cross-section series that fulfills all designs with a design criterion smaller than the maximum allowable utilization defined in the Global Settings dialog.
To optimize a cross-section, click into the corresponding cell of the 'Use Different Cross-Section for Design' table column. Then select the Optimize option in the list.
The editing dialog of the cross-section appears. In the 'Optimization | Timber Design' tab, you can define the parameters for the optimization.
Check the parameter(s) to be changed in the 'Geometry' column. In the 'Min' and 'Max' columns, you can then enter the lower and upper limits of the parameter. The 'Step' controls the interval in which the dimensions of the parameter vary during the optimization process. If the 'aspect ratios are to be maintained', check the corresponding check box and specify the parameters for the optimization of the outer dimensions.
The same conditions apply to cross-section optimization as when using a different cross-section (see above). The designs are carried out for all cross-section variants with the internal forces of the structural analysis. Then the optimal variant is output in the table column. The effects of the changed cross-section on the stiffnesses and internal forces in the RFEM/RSTAB model are not considered. Therefore, use the options of the context menu to transfer the optimized cross-sections to the model (see image Context menu when using a different cross-section).
A comprehensive structural optimization is possible with the Model Optimization add-on.