Example of 'Simplified' Vibration Analysis for EC 5

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Tips & Tricks

In an earlier post, we looked at the possibility of satisfying the minimum frequency in RF‑/TIMBER Pro. In this post, we want to illustrate this topic by in an example.

We analyze a three‑span beam in a dwelling house. To avoid discomfort caused by persons, the system shall have a minimum fundamental frequency of 8 Hz. To consider this in RF‑/TIMBER Pro, you can determine the maximum allowable deflection of the middle span by means of the expression for three‑span beams (see PDF document). In this case, the middle span may deform by -1 mm to comply with the frequency criterion. The actual deflection under permanent load (2.1 kN/m) is obtained as -0.683 mm. Thus, the design of the fundamental frequency is satisfied. Check calculations result in a fundamental frequency of 9.68 Hz, the FEM calculation gives 9.76 Hz.


Dipl.-Ing. (FH) Gerhard Rehm

Dipl.-Ing. (FH) Gerhard Rehm

Product Engineering & Customer Support

Mr. Rehm is responsible for the development of products for timber structures, and provides technical support for customers.


Vibration design Stiffness criterion Vibration velocity Vibration acceleration Natural frequency



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  • Updated 29 October 2020

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RFEM Timber Structures
RF-TIMBER Pro 5.xx

Add-on Module

Timber design according to Eurocode 5, SIA 265 and/or DIN 1052

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1,120.00 USD