I would like to design a cross-section in RF‑/STEEL Cold‑Formed Sections that is not contained in the cross-section library of RFEM/RSTAB. What should I do?

Answer

Common cold-formed cross-sections can be modeled in SHAPE‑THIN. In General Data, select the "c/t parts and effective cross-section properties" check box (Figure 01).

Figure 01 - General Data

Then, select the "EN 1993‑1‑3 (Cold formed cross-section)" option in the "c/t-Parts and Effective Cross-Section" tab of the Calculation Parameters dialog box (Figure 02).

You can optionally check the geometric conditions for the applicability of the standard specified in EN 1993‑1‑3 [1], 5.2. To do this, select the corresponding check boxes. If the geometric conditions are not met, an error message appears before the calculation.

Figure 02 - Calculation Parameters

First, enter the elements of the cross-section. The notional flat widths are usually generated automatically from the geometry conditions, but can also be created as user-defined in Table "1.7 Notional Flat Widths | EN 1993‑1‑3" (Figure 03) or in the corresponding dialog box.

Figure 03 - Table 1.7 Notional Flat Widths | EN 1993-1-3

Then, you can define stiffeners in Table "1.8 Stiffeners" or in the corresponding dialog box (Figure 04).

Figure 04 - Table 1.8 Stiffeners

Furthermore, you should specify the buckling panel in Table "1.9 Buckling panels" (Figure 05) or in the dialog box. To do this, select the elements of the buckling panel. The stiffeners located in the stiffened panel are identified automatically.

Figure 05 - Table 1.9 Panels

For the design of a cold-formed cross-section in RF‑/STEEL Cold‑Formed Sections, it is sufficient to define the stiffeners and panels of the cross-section. It is not necessary to additionally calculate the effective cross-section in SHAPE‑THIN. Thus, you can start the calculation and click "OK" to confirm the warning message (Figure 06).

Figure 06 - Warning "Effective Cross-Section Values Cannot Be Calculated"

After saving the calculated cross-section, it can be imported into RFEM or RSTAB.

Keywords

Cold formed cross-section Cold-formed cross-section

Reference

[1]   Eurocode 3: Design of steel structures - Part 1‑3: General rules - Supplementary rules for cold-formed members and sheeting; EN 1993‑1‑3:2010‑12

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Cross-Sections Thin-Walled
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Properties and stresses of thin-walled and cold-formed cross-sections

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