Page 253 - Numerical Analysis and Modelling in Geomechanics

234 SEISMIC MICROZONING USING NUMERICAL MODELLING

Figure 8.7 Scheme 1D of SHAKE.

Figure 8.8 Typical behaviour of shear modulus vs shear strain.
Once the amplification function is computed using the SHAKE method, the
power spectrum of any top of layer and the corresponding response spectrum at
any level of exceedence probability is obtained.
The limitations of the 1D model are:

• The hypothesis that layers are perfectly horizontal and unbounded. Such an
ideal situation rarely exists in reality;
• The hypotheses that waves are vertically propagating and composed by pure
shear components;