Stability Analysis of Cross-Laminated Timber Walls Using Eigenvalue Analysis
Tips & Tricks
The previous post of this series clarified the stability analysis of cross‑laminated timber (CLT) walls with a result beam. Another way is a plate buckling analysis by means of an eigenvalue analysis using RF‑STABILITY and RF‑IMP.
For this purpose, a rigidity in a spatial model is generated in the RF‑LAMINATE add‑module, as already explained in the previous posts and in the related webinars. These rigidities generate failure forms in RF‑STABILITY, that are used to determine the critical load factors. As you can see in Figure, the buckling of the lower wall is examined.
Based on this eigenvector, the RF‑IMP generates a pre‑deformed initial model that takes into account the buckling of the lower wall. The applied pre‑deformation according to EN 1995‑1‑1 for members would be just under 10 mm. This is the value by which the finite elements of the surface are maximally deflected.
Further eigenvalue analysis with this deformed system must be carried out in RF‑STABILITY. The stability design is successful only if the critical load factor as a result of this analysis is greater than 1.
In the end, the pre‑deformed system is analyzed in a stress-based design in RF‑LAMINATE. The additional bending moments of the deformed system results in a greater design ratio.
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Stability analysis according to the eigenvalue method
Generation of equivalent geometric imperfections and pre-deformed initial structures for nonlinear calculations