Get Movement from low frequency building vibrations

Hi,

I want to calculate the movement of an structure with an very low frequency of 0,3Hz. I tried to do this with an double integration. I tried several settings for the filter but it never worked good enough. For testing I created an ideal Sinus with 0,3Hz and integrated it. The problem is that the damping is much to high. Below you see that the input signal goes up to three but the double integrated signal goes only up to 0,6 m. Can anybody tell me how to fix this problem? Actually the integrated signal should also go up to three. Or am I thinking about this the wrong way?

Best regards

Fabian

@Fabian Hoppe

Mathematically, double integration of your initial 0,3 Hz signal with A = 3 will reduce the numerical value as shown in the equation below:

Furthermore, please note that you have input a high pass filter frequency cutoff at 0,3 Hz. The signal will likely be attenuated (dampened) by the filter itself. In any case, we do not support settings where the filter cutoff is below 1 Hz, and we cannot guarantee accurate results under these conditions.

EDIT: Low cutoff frequencies are absolutely supported.

Regards, Staš Jevševar

@Staš Jevševar

Thanks for you fast answer. The problem is that the frequence of buildings is very low <1Hz. In your manual you even write about this low frequencies (e.g. 0,3Hz) and recommend them. Does that mean that the Dewesoft Software is actual not suitable for structural Health Monitoring? :

Best regards

Fabian

I'm sorry regarding the frequency, I was mislead by a bug we have. We absolutely support structural health monitoring and low frequencies are no issue.

https://dewesoft.com/applications/structural-health-monitoring

There's no issue with low frequencies although you should still have the cutoff lower than the actual frequency.

I've also edited my original response.