In the Cross-sections table of the 'Timber Design' category, all cross-sections you have created in the model are listed.
Permissible cross-sections
The timber design of member cross-sections is based on standard. Whether a cross-section is permissible and also relevant for design can be recognized by the font color. The colors mean:
- black: cross-section is suitable for 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, the types
and
of the Standardized category, as well as
of the Composite category are permissible. Cross-sections from the cross-section properties program RSECTION can also be designed, provided the calculation is carried out using finite element analysis.
A material of the Timber type must be assigned to all cross-sections.
The categories of the individual cross-sections are specified in the table column 'Cross-section type'.
Objects with an invalid cross-section are not considered in the design – even if the 'To be designed' option is activated for this cross-section. They are automatically listed in the table Objects to be Designed as 'Not valid / deactivated'.
Remove cross-section from design
For a valid cross-section, you can exclude all objects assigned to the cross-section from the design by deactivating the 'To be designed' checkbox. This classifies these objects in the table Objects to be Designed as 'Not valid / deactivated' and they are not checked in the design.
Modify cross-section
If necessary, you can adjust the properties of a cross-section in the edit dialog. To do so, double-click the row of the cross-section or click the
button in the table toolbar.
Icons for defaults or modified values are displayed in the table column 'Options' (see image Table 'Cross-sections'). They provide a quick overview of the cross-sections used. The
icon, for example, is assigned to a rotated cross-section.
Use another cross-section for design
You can use a different cross-section for design than for the RFEM/RSTAB calculation: To do this, click in the corresponding row of the table column 'Use another cross-section for design'. You can then import a cross-section from the library using the
button.
If another cross-section is stored in the column, further options are available in the context menu. These allow 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.
Optimize cross-section
The Timber Design Add-On offers the option 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 satisfies all design checks with a utilization ratio less than the maximum permissible utilization defined in the Global Settings dialog.
To optimize a cross-section, click the corresponding cell in the table column 'Use another cross-section for design'. In the list, select the Optimize option.
The edit dialog of the cross-section appears. In the 'Optimization | Timber Design' tab, you can define the parameters for the optimization.
In the 'Geometry' column, select the parameter(s) to be changed. In the 'Min' and 'Max' columns, you can then enter the lower and upper limits of the parameter. The 'Increment' controls the interval in which the dimensions of the parameter vary during the optimization process. If the 'Maintain aspect ratios' is to be preserved, select the corresponding checkbox and enter the parameters for the optimization of the outer dimensions.
The same conditions apply for cross-section optimization as for using another cross-section (see above). The design checks are carried out for all cross-section variants with the internal forces of the structural analysis. The optimal variant is then 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 taken into account. Therefore, use the context menu options to transfer the optimized cross-sections to the model (see image Context menu when using another cross-section).
Comprehensive structural optimization is possible with the Model Optimization Add-On.