FAQ 003544 | I would like to carry our the flexural buckling analysis for timber components with ...


First Steps with RFEM

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We provide hints and tips to help you get started with the RFEM program.

9 September 2019


Gerhard Rehm

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I would like to carry out the flexural buckling design for timber components with imperfections and internal forces according to the second-order analysis. Is it sufficient to activate this in Details of the RF‑/TIMBER Pro add-on module or is it necessary to make additional settings?


The setting in Figure 01 only controls the effect on the design side. After activating this function, the buckling designs in the "Effective Lengths" window are deactivated. Thus, the lateral-torsional buckling analysis is only performed.

Figure 01 - Detailed Settings in RF-/TIMBER Pro Add-on Module

In order to calculate with the design values of stiffnesses, it is necessary to reduce them by the partial safety factor according to [1]. For this, select the highlighted option in the calculation parameters (see Figure 02).

Figure 02 - Reduction of Stiffness by Partial Safety Factor

If using the automatic combinations for the standard EN 1990 + EN 1995, this setting is automatically activated in the combinations for ULS according to the second-order analysis. In the case of the combinations for SLS and the combinations generated according to the linear static analysis, this option is automatically deactivated. However, the combinations are only assigned automatically by using the method of analysis in the "Combination Expressions" tab (see Figure 03).

Figure 03 - Calculation Method of Combinations

If you want to calculate the component stiffnesses with the 5% quantile value of the stiffness parameters divided by the partial safety factor, you have to additionally activate the "Modify stiffnesses" option in the calculation parameters and modify the stiffnesses manually.

Figure 04 - Modifying Stiffnesses for Load Combinations


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