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Page Title:
Appendix E: Outline of Steps to Develop PSEUDO-Mean Correction Factor - Continued |
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|  DOE-STD-1024-92
These are composite LLNL/EPRI mean/median ratios.
4.
From Cornell to translate mean/median hazard ratio to ground motion.
GMratio = y-1/b
where
b = slope of hazard curve.
y = mean/median hazard ratio.
We have tabulated ground motion ratios at different probabilities.
A5/A3 = (.01)-1/b
From Cornell
b = 2/log (A5/A3)
A5/A4 = (.1)-1/b
b = 1/log (A5/A4)
A4/A3 = (.1)-1/b
b = 1/log (A4/A3)
5. Summary of Hazard Curves Slope.
A5/A4 = pga at 10-5/pga at 10-4
A4/A3 = pga at 10-4/pga at 10-3
# of sites
median
mean
r
LLNL
A5/A4
16
2.32
2.28
.18
EPRI
A5/A4
58
2.47
2.61
.54
LLNL
A4/A3
53
2.64
2.64
.19
EPRI
A4/A3
58
3.90
4.12
.93
To arrive at composite estimate use only sites that have both LLNL and EPRI.
Composite A5/A4
Sites = 13
n=26
mean = 2.44
r = .39
Composite A4/A3
Sites = 48
n=96
mean = 3.30
r = .91
Compare to geometric average of individual LLNL + EPRI.
Composite A5/A4 = (2.28 * 2.61)-1/2 = 2.44
Composite A4/A3 = (2.64 * 4.12)- = 3.30
Values are the same.
6.
From composite A5/A4 and A4/A3 calculate b at
A5/A4 b = 1/log (2.44) = 2.58
A4/A3 b = 1/log (3.30) = 1.93
E-2
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