Damping

The seismic waves are amplified in the structure, because of the pulses of the wave. However, the structure tries to relief these efforts according to the damping, which is the capacity of the structure to dissipate energy. Therefore, structures after an earthquake continue moving after the struck.

Usually a 5% of damping and a natural period of T=n/10 is related to buildings (n is the number of stories).

Response Spectrum Accelerations (RSA) can be constructed in different ways:

Single parameter scaling:

a)      RSA is anchored to the PGA at zero period. RSA=C/T^n

b)      RSA is anchored by the maximum response spectrum acceleration RSAmax. RSA=C/T^n.

c)      RSA is scaled by the PGV (a=PGV/750 in Australia, AS1170.4, 1993)

Dual parameter scalling, that is to say, RSA is scaled by SaT=0,3s y SaT=1,0s. RSA=SaT1/T

Multiple parameter scalling. From data obtained for a range of periods.