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KB 000577 | Using Buckling Members for Unstable Models
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First Steps with RFEM
Description
If the calculation of a member model according to the second-order analysis is terminated with an error message, this instability is often caused by the failed tension members: As soon as compression forces occur in the tension member during a calculation step, this member is no longer considered in the following iterations. Thus, the model can become instable.
Keywords
Dlubal Knowledge Base Instability Calculation break-off Tension member Buckling member L-section Angle Bracing Dlubal KB Knowledge Base Technical Contribution
Links
- Useful Tools for Fast Generation of Structures in RFEM
- Useful Tools for Fast Generation of Structures in RSTAB
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Using Buckling Members for Unstable Models
If the calculation of a member model according to the second-order analysis is terminated with an error message, this instability is often caused by failed tension members: As soon as compressive forces appear in a tension member during a calculation step, this member is no longer considered in the following iterations. Thus, the model can become unstable.
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.
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- I would expect the results from my load combination (CO) set to a linear analysis to equal the summation of the results from my load cases (LC) also set to a linear analysis. Why do the results not match?
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- In connection with the calculation according to the large deformation analysis, I get significantly smaller deformations than for the calculation according to the linear static or second-order analysis. How is this possible?
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