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# Minimum allowable frequency of a structure - Eurocode provision?

## Minimum allowable frequency of a structure - Eurocode provision?

(OP)
Hello everyone, i am designing a two storey RC Frame house according to Eurocode. My question is, is there any EC8 provision that sets a minimum for the fundamental frequencies for certain types of structures?

Regards

### RE: Minimum allowable frequency of a structure - Eurocode provision?

I'm not aware of any special provision for the fundamental frequencies in EC8. However, the drift limits will probably govern if the stiffness of your structure is too low.

### RE: Minimum allowable frequency of a structure - Eurocode provision?

(OP)
Hi,

are you referring to the interstorey drift sensitivity coefficient?

EC8-1: 4.4.2.2 (2) Eq. 4.28

θ = (Ptot x dr) / (Vtot x h) ≤ 0.1

### RE: Minimum allowable frequency of a structure - Eurocode provision?

Not exactly. That theta coefficient is used to determine the sensitivity of the structure to global second-order effects and wheter they should be taken into account into the global analysis of the structure or not. It is directly correlated to the building stiffness, and you do need to check it during your analysis.
However, I was talking specifically about the damage limitation requirements that need to be satisfied with the limitation of the interstorey drifts (4.4.3.2). These will probably govern your design if your structure is too flexible.

### RE: Minimum allowable frequency of a structure - Eurocode provision?

(OP)
Ok now i understand what you mean. My values are well below the limit. so it should be fine. Next i will need to check on the elements individually.

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