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FAQ 002844 | I used double members when entering members. Do I have to consider anything else or is it better to enter a member with double cross-section properties?
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I used double members when entering members. Do I have to consider anything else or is it better to enter a member with double cross-section properties?Answer
To design multi-part components, you can use the composite cross-sections of the cross-section library. In this case, the cross-section values are calculated automatically from the individual cross-sections and then also considered in the add-on modules for design. The shear-resistant connection of lattice members is shown here by entering an equivalent plate thickness t *.
Figure 03 - Combined cross-section
If you have edited the cross-section properties of a cross-section or the stiffnesses of a member with the "Modify Stiffness" function, they are generally not used in the design modules. The modified stiffnesses are only used for the calculation of internal forces.
Figure 01 - Stiffness modification in the calculation of internal forces
Figure 02 - Single angle with modification of stiffness
The designs in RF-/STEEL EC3 also require the exact dimensions and the shape of the cross-section for the c/t design or the selection of the interaction equation, for example. The effect of the stiffness modification on these individual parameters is not unique for all cases and thus cannot be used in the add-on module.
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Dlubal FAQ Modify stiffness Steel design Design Double members Frequently Asked Question FAQ about Dlubal Question and Answer about Dlubal
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Manual adjustment of the buckling curve according to EN 1993-1-1
The RF-/STEEL EC3 add-on module automatically transfers the buckling line to be used for the flexural buckling analysis for a cross-section from the cross-section properties. In particular for general cross -sections, but also for special cases, the assignment of the buckling line can be adjusted manually in the module input.
SHAPE-THIN | Cold-Formed Sections
SHAPE-THIN determines the effective cross-sections according to EN 1993-1-3 and EN 1993-1-5 for cold-formed sections. You can optionally check the geometric conditions for the applicability of the standard specified in EN 1993‑1‑3, Section 5.2.
The effects of local plate buckling are considered according to the method of reduced widths and the possible buckling of stiffeners (instability) is considered for stiffened sections according to EN 1993-1-3, Section 5.5.
As an option, you can perform an iterative calculation to optimize the effective cross-section.
You can display the effective cross-sections graphically.
Read more about designing cold-formed sections with SHAPE-THIN and RF-/STEEL Cold-Formed Sections in this technical article: Design of a Thin-Walled, Cold-Formed C-Section According to EN 1993-1-3.
- I used double members when entering members. Do I have to consider anything else or is it better to enter a member with double cross-section properties?
- Why do I get high differences when designing a longitudinally stiffened buckling panel compared to the German and Austrian National Annexes?
- How can I perform the stability analysis for an edgewise supported flat steel, for example 100/5, in RF-/STEEL EC3? Although the cross-section is rotated by 90 ° in RFEM/RSTAB, it is displayed lying flat in RF-/STEEL EC3.
- How can I create a curved or curved section?
- How are the signs to be interpreted for the release results of the line release and line hinges?
- How are hot -dip galvanized components considered for fire protection in the Steel EC 3 add -on module?
- How is the rotational stiffness of a buckling stiffener determined in FE-BUCKLING?
- In RF-/STEEL EC3, is the "Elastic design (also for cross-section class 1 and 2)" option under "Details → Ultimate Limit State" considered for the stability analysis when activated?
- How can I get the member end forces to design the connections?
- I would like to calculate and design "temporary structures." What do I need for this?
