RF-/STEEL EC3 - Online Manual Version 5/8

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RF-/STEEL EC3 - Online Manual Version 5/8

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3.1.7 General


Figure 3.11 Dialog box Details, tab General
Calculation of Result Combinations with OR Type

If combinations are created automatically, usually many load combinations (CO) are produced. Generally, these combinations are summarized in a result combination (RC) as alternatively acting in an 'OR' connection which provides the envelope: CO1/p or CO2/p or CO3/p or CO4/p etc. For the design of these result combinations, you have two possibilities in RF-/STEEL EC3.

The load components of the contained combinations can be analyzed separately. Thus, the elastic critical moments for lateral-torsional buckling are determined separately for each constellation, and the designs are performed accordingly. This approach provides exact results. However, it is very time-consuming and requires a high computational effort.

Alternatively, it is possible to Analyze result combinations generally. This calculation runs considerably faster because RF-/STEEL EC3 uses only the extreme values with the corresponding internal forces for the design. However, the result may be incorrect if the RC includes a combination where several internal forces (such as N and My) are together just below the extreme values.

Cross-Section Optimization

By default, the optimization is targeted on the maximum allowable design ratio of 100%. If necessary, you can set a different design ratio in this text box.

Check of Member Slendernesses

In both text boxes, you can specify the limit values λlimit in order to define the member slendernesses. Separate specifications are possible for members with tension forces only and for members with bending and compression.

In Window 3.3, the limit values are compared to the real member slendernesses. That window is available after the calculation (see Chapter 4.8) when the corresponding check box in the Display Result Windows section to the right has been selected.

Design of Welds

When you select this check box, weld designs will be performed in the course of the analysis. The program performs the typical designs according to EN 1993-1-8 [12]. After the calculation, you find the results listed among the cross-section designs (see also the article in the Knowledge Base on our website).

Display Result Windows

In this dialog section, you can select which result windows including parts list are displayed. The windows are described in Chapter 4.

Window 3.3 Member Slendernesses is deactivated by default.

[12] Eurocode 3: Design of steel structures - Part 1-8: Design of joints; EN 1993‑1‑8:2005 + AC:2009