Cross-Laminated Timber Wall Elements | RFEM | Info Day Online | 15.12.2020 | 3/4

The following article describes a design using the equivalent member method according to [1] Section 6.3.2, performed on an example of a cross-laminated timber wall susceptible to buckling described in Part 1 of this article series. The buckling analysis will be performed as a compressive stress analysis with reduced compressive strength. For this, the instability factor k_c is determined, which depends primarily on the component slenderness and the support type.

Basically, you can design the structural components made of cross-laminated timber in the RF-LAMINATE add-on module. Since the design is a pure elastic stress analysis, it is necessary to additionally consider the stability issues (flexural buckling and lateral-torsional buckling).

The vibration design of cross‑laminated timber plates often governs for wide-span ceilings. The advantage of timber as a lighter material compared to concrete is turned into a disadvantage here, since a high mass is advantageous for a low natural frequency.

• General stress analysis
• Graphical and numerical results of stresses and stress ratios fully integrated in RFEM
• Flexible design with different layer compositions
• High efficiency due to few entries required
• Flexibility due to detailed setting options for basis and extent of calculations
• A local overall stiffness matrix of the surface in RFEM is generated on the basis of the selected material model and the layers contained. The following material models are available:
  • Orthotropic
  • Isotropic
  • User-defined
  • Hybrid (for combinations of material models)
• Option to save frequently used layer structures in a database
• Determination of basic, shear, and equivalent stresses
• In addition to the basic stresses, the required stresses according to DIN EN 1995-1-1 and the interaction of those stresses are available as results.
• Stress analysis for structural surfaces including simple or complex shapes
• Equivalent stresses calculated according to different approaches:
  • Shape modification hypothesis (von Mises)
  • Shear stress hypothesis (Tresca)
  • Normal stress hypothesis (Rankine)
  • Principal strain hypothesis (Bach)
• Calculation of transversal shear stresses according to Mindlin or Kirchhoff, or user-defined specifications
• Serviceability limit state design by checking surface displacements
• User-defined specifications of limit deflections
• Possibility to consider layer coupling
• Detailed results of individual stress components and ratios in tables and graphics
• Results of stresses for each layer in the model
• Parts list of designed surfaces
• Possible coupling of layers entirely without shear

RFEM and RSTAB models can be saved as 3D glTF models (*.glb and *.glTF formats). View the models in 3D in detail with a 3D viewer from Google or Babylon. Take your VR glasses, such as Oculus, to "walk" through the structure.

You can integrate the 3D glTF models into your own websites using JavaScript according to these instructions (as on the Dlubal website Models to Download).

With the Camera Fly Mode view option, you can fly through your RFEM and RSTAB structure. Control the direction and speed of the flight with your keyboard. Additionally, you can save the flight through your structure as a video.