Timber - beam panel connectors

Product Support
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1

Hello,

I am working with RFEM 6.12 and I have two related questions regarding beam panels and line hinges.

  1. Automatic generation of line hinges

When I create a beam panel and assign connector definitions (see Image 1), RFEM automatically generates rigid links associated with line hinges.

Is it possible to know which calculations RFEM performs to determine the stiffness values of those line hinges (see Image 3)?

In particular:

  • Are these stiffness values derived from analytical formulas?
  • Are any formulas from Eurocode 5, Table 7.1, used internally to calculate the translational and/or rotational stiffness of the line hinges?
  1. Manual definition and calibration of line hinge stiffness (EC5-based)

I am trying to calibrate the numerical model to reproduce as accurately as possible the results of a laboratory test.

The following aspects are already correctly defined:

  • Material properties
  • Geometry of the panel
  • Cross-sections of the members

The remaining uncertainty lies in the connections, which is where I still have some freedom to adjust the model.

For that reason, I cancel the generated state. However, I would like to better understand how a line hinge is defined mechanically in RFEM.

At this stage, I am not sure whether it is appropriate to use the formulas from Eurocode 5, Table 7.1, for this purpose. Therefore, I would appreciate your opinion on the following points:

  • Which approach is recommended to define the stiffness of a line hinge representing a bolt or a group of bolts?
  • Whether EC5 Table 7.1 can be used to derive equivalent spring stiffness values, or if another methodology is more suitable.
  • How such stiffness values should be implemented in RFEM (e.g., springs, line hinges, etc.).

Thank you for your support.

Image 1
Image 11913×1016 110 KB

Image 3
Image 3827×225 22.1 KB

3

Hi MarianaG,

thank you for your question.

I think the background informations you are asking for are handeled in the following articles.

https://www.dlubal.com/en/support-and-learning/support/knowledge-base/001876

https://www.dlubal.com/en/support-and-learning/support/knowledge-base/001923

I hope this answers your questions. Let me know if you have any others and I`ll be happy to help.

Best regards
Bastian Kuhn

4

Thank you so much for your help. I have been searching for articles containing this information for a long time.
One last question: when the connection is modelled as a nail connection, could you please clarify which formulation the software applies? Specifically, does it use the formula highlighted in red or the formula highlighted in green in the attached image?

Image EC5 - Table 7.1
Image EC5 - Table 7.11208×348 65.2 KB

Thank you for your time and support.
Kind regards,
Mariana G.

5

Hi MarianaG,

thank you for your answer.

For nails, we use the following equation:

k_{\mathrm{ser}} = \frac{\rho_m^{1.5} \cdot d^{0.8}}{30}

In the example from the links, the recalculation works as follows (assuming a nail diameter of d=5 mm:

k_{\mathrm{ser}} = \frac{515^{1.5} \cdot 5mm^{0.8}}{30} \approx 1413,5 \, \text{N/mm}

With n=13 connectors (per the example), this gives:

C_{u,x} = k_{\mathrm{ser}} \cdot n \approx 1413,5 \, \text{N/mm} \cdot 13 \approx 18375 \, \text{kN/m^2}

This value you can find in the result then of the rigid links. Please see the following picture.

image
image608×176 4.32 KB

I hope this answers your questions. Let me know if you have any others and I`ll be happy to help.

Best regards
Bastian Kuhn

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