Chiou and Youngs PEER-NGA Empirical Ground Motion Model for ...

Amplification Factor
3
1
0.5
0.3
EPRI & Peninsular Range; 0.01 Sec;
0.001 0.003 0.01 0.03 0.1 0.3 1 3 10
Figure 24: Soil amplification as a function of ground motion level from 1-D equivalent linear site
response analyses (Silva, 2004). Colors denote VS30 as follows: light blue - 150m/s, magenta -
270m/s, green - 400m/s, red - 560m/s, and blue - 750m/s.
Coef. a (log of Low-Strain Amp. Factor)
Coef. a (log of Low-Strain Amp. Factor)
-0.2 0.4 0.8 1.2 1.6 2.0
-0.2 0.4 0.8 1.2 1.6 2.0
0.01 Sec; Coefficient a
200 300 500 700 1000 2000 3000
Vs30 (m/sec)
0.0105 Sec; Coefficient a
200 300 500 700 1000 2000 3000
Vs30 (m/sec)
C&Y2006 Page 31
RockSA
Coef. b
Coef. b
-1.6 -1.0 -0.4 0.0
-1.6 -1.0 -0.4 0.0
0.01 Sec; Coefficient b
200 300 500 700 1000 2000 3000
Vs30 (m/sec)
0.0105 Sec; Coefficient b
200 300 500 700 1000 2000 3000
Vs30 (m/sec)
Figure 25: Fit of models for coefficients a and b to the 1-D site response results from Silva (2004).
The dashed lines represent fits using the functional forms in Equation 15.
Choi and Stewart (2005) developed a model for the dependence of nonlinear site
amplification on VS30 and the level of input rock motion. Figure 26 compares the variation of
the parameter b computed from their models with results obtained from fitting Equation (15)