1 December 2017

FAQ 000090 EN

Robert Vogl

Add-on Modules

RF-FE-LTB

FE-LTB

RSTAB

RFEM

I have defined a pre-deformation in RSTAB. If FE-LTB takes over the loads, why not the imperfection?

Answer

According to EN 1993-1-1 and DIN 18800 Part 2, it is necessary to get specified the equivalent geometrical imperfections for the second-order calculation to determine geometric and structural imperfections as well. This pre-deformation should be applied affinely to the lowest buckling or lateral-torsional buckling mode.

Therefore, in the program FE-LTB, the eigenmode belonging to the smallest eigenvalue is calculated (preliminary eigenvalue analysis) and then chosen as initial deformation mode. The imperfection approach is then carried out by the user scaling the eigenmode.

Thus, in RF-/FE-LTB, the pre-deformation is based on the eigenmode. The imperfections defined in RFEM/RSTAB are irrelevant and are therefore not adopted.

Keywords

Imperfection Precamber Eigenmode Equivalent imperfection

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RFEM Steel and Aluminium Structures
RF-FE-LTB 5.xx

Add-on Module

Lateral-torsional buckling analysis of members according to the second-order analysis (FEM)

Price of First License
900.00 USD
RSTAB Steel and Aluminium Structures
FE-LTB 8.xx

Add-on Module

Lateral-torsional buckling analysis of members according to the second-order analysis (FEM)

Price of First License
900.00 USD
RSTAB Main Program
RSTAB 8.xx

Main Program

The structural engineering software for design of frame, beam and truss structures, performing linear and nonlinear calculations of internal forces, deformations, and support reactions

Price of First License
2,550.00 USD
RFEM Main Program
RFEM 5.xx

Main Program

Structural engineering software for finite element analysis (FEA) of planar and spatial structural systems consisting of plates, walls, shells, members (beams), solids and contact elements

Price of First License
3,540.00 USD