The calculation of eigenfrequencies are performed based on a number of different parameters.

Based on the concrete strength, the E-modulus is calculated for each step as the strength increases over time. The contribution of the reinforcement in the calculation is also considered.


As for L, the span is taken depending on the positions of the supports, that are also changed between the differrent stages.

As for the topping, it will be considered with regards to its geometry and material properties, if it is "Cast". "None" or "Wet" will not be considered

It is also considering if the cross section is cracked in some cases. Therefor the frequency might vary to some extent over the different stages.

Note that this is a serviceability check, so any eigenfrequency in ultimate limit state will use design values for materials, and not characteristic values.

Only the deadload of the beam will be considered in me.


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PRE-Stress Documentation