You can create simple imperfections related to a member or a member set in an imperfection case of the type 'Local Imperfections'. For this, use the Member Imperfections object that you create by clicking the [Select] button
in the toolbar.
In addition to the absolute or relative input options for inclinations and precambers, you have other specification options for various design standards. Further information can be found in Chapter Member Imperfections of the RFEM manual.
Member set imperfections correspond to the member imperfections in terms of function, but are related to a member set.
Calculation
In the calculation, the loads resulting from the imperfection shape are represented by equivalent loads. The horizontal equivalent load for inclination and precamber is calculated from the compressive force in the member. For elements with tensile stress, the imperfection is not taken into account and no equivalent forces are applied.
In a calculation with 7 degrees of freedom, the additional torsional moment resulting from the transverse load is also taken into account for the precamber.
The internal forces are averaged over one FE element. Therefore, if the distribution of internal forces is not constant, you should pay attention to a sufficiently fine FE division.
If you require a displacement of the FE mesh nodes or define a specific shape as an imperfection shape, the scaled buckling shape and the imperfection due to static deformation are available as further imperfection types. } are available.
Use
The member imperfection always refers to the length of the entire member. Therefore, it is necessary to divide the members for a multi-shaft imperfection shape.