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I would like to analyze bending buckling for timber components with imperfections and internal forces according to the second-order analysis. Is it sufficient to activate it in Details in the RF- / TIMBER Pro add-on module, or are other settings necessary?


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

In order to calculate with the design values of the stiffnesses, they have to be reduced by the partial safety factor according to [1] . To do this, select the marked option in the calculation parameters (see Figure 02).

If the automatic combinatorics was used for the standard EN 1990 + EN 1995, this setting is automatically activated for combinations for the ULS according to the second-order analysis. For combinations for SLS, this option is automatically deactivated as well as for combinations generated according to the 1st order. However, the automatic assignment is only carried out by means of the calculation type in the "Combination Expressions" window (see Figure 03).

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 Stiffness" function in the calculation parameters and modify the stiffnesses manually.


Second-order analysis Buckling Stability analysis Timber structures Equivalent member method


[1]   Eurocode 5: Design of timber structures - Part 1-1: General - Common rules and rules for buildings; EN 1995-1-1:2010-12


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