Vishisht Bhaiya

Mohit Bhandari

Kindly add some massala to this question by a very good friend of me.

Regards.

Mohsen, we are waiting for your Feedback

Mohsen Azimi

By Scaling down the PGA of a specific earthquake record, the ratio of PGV/PGA remains the same. But yes, low PGA value will offer less acceleration and velocity components of the earthquakes.

so my suggestion to you is:

1. Use the earthquake records, which have less PGV/PGA ratio, of the order of 80-100 cm/s/g

2. Normalize all the earthquakes and scale them down to a less PGA value, e.g., 0.2g.

Mohit Bhandari Thanks a lot my very good friend.

Mohit Bhandari Thank you for this response

I do not think that the PGA will only affect the structure to cross the elastic limit. I would say the moment the frequecy contents of the earthquake lays nearby the natural frequencies of the structure will cause the structure to cross the elastic limits. In scaling if you are multplying the whole time history data by a factor should affect on frequency contents.

Thank you Said Elias

Dear all,

Mathematically, scaling down the PGA of theses records does affect the frequency content, of course, on the amplitude. But, since the "frequency content" is linked to the energy of a signal at the spectific frequency range of a signal, in respect with the natural one, the scaling down the PGA value has not influence on the frequency content.

Regards,

You may scale down/ up earthquake history. This does not affect frequency content. Consider that uou have a pulse u(t)= asinwt. If you scale up or down, w remains same. This applies to earthquake also as that is nothing but summation of numerous sinusoids.

Note that, you are assuming that your response is co-related to PGA only in elastic range which is true if your structure is very stiff. In the medium and long period, PGV and PGD govern (basic concept of response spectrum).

Further, I must mention that scaling of motion is deficient intrinsically because the shape of the relevant spectra remains unaffected by such manipulation which is inconsistent (due to seismological reasons refer to Book of Elnashai and Di Sarno).

scaling the earthquake records do not affect the frequency content but only the amplitudes.