3.3 Cross-Sections

This window lists the cross-sections used for the design. In addition, you can make specifications for optimization.

The cross-sections defined in RFEM are preset along with the assigned material numbers.

To modify a cross-section, click the entry in column B to activate the field. Then, use the [Cross-Section Library] button, click in the text box, or press the [F7] key to open the cross-section table of the current input field (see Figure 3.18).

A dialog box opens where you can select a different cross-section or a different cross-section table. The following Solid Cross-Sections are enabled for the design in RF-CONCRETE Members:

• Rectangle
• Floor beam (symmetric, unsymmetric, or conic)
• Rotated floor beam (symmetric or unsymmetric)
• I-shape (symmetric, unsymmetric, or conic)
• Circle
• Ring
• Hollow rectangle (Z-symmetric)
• Conic shape (symmetric)
• U-section (symmetric)

Selecting cross-sections from the library is described in chapter 4.13 of the RFEM manual.

You can also enter the new cross-section description directly into the text box. If the entry is already listed in the database, RF-CONCRETE Members will import the properties.

A modified cross-section is highlighted in blue.

If the cross-sections in RF-CONCRETE Members are different from the ones used in RFEM, both are displayed in the graphic to the right of the table. The designs will be performed for the cross-section selected in RF-CONCRETE Members, using the internal forces from RFEM.

Each allowable cross-section can run through an optimization process. For the internal forces determined in RFEM, the program finds the cross-section that meets the specifications of the Optimization Parameters dialog box with the least possible dimensions (see Figure 8.5).

To optimize a certain cross-section, select its check box in column C. Recommendations for optimizing cross-sections can be found in Chapter 8.2.

This column shows remarks in the form of footnotes. They are explained in the status bar.

Column E shows the values of the creep coefficients φ (t,t₀) and shrinkage strains ε (t,t_s). The values are determined from preset parameters. They can be adjusted with the button that appears after clicking into the text box. A new dialog box opens.

The Counting Form for the creep coefficient and the shrinkage strain is possible in two ways:

• Age : The values are calculated by the program using parameters.
• Defined : The values must be specified directly.

At the end of the table, the Result determined from the parameters is displayed for the creep coefficient φ (t,t₀) and the shrinkage strain ε (t,t_s). The determination of the creep coefficient and shrinkage strain is described in Chapter 2.2.6.

In the Set Settings for dialog section, you can define whether the specifications apply to a particular cross-section, all cross-sections, or selected cross-sections.

The Info About Cross-Section dialog box provides information on the cross-section's properties.