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records have higher amplitudes in high frequency (low-
period) ranges.
· The difference in spectral shape between WUS and CEUS
records is more evident for the rock records.
· Having larger amplitudes at long periods implies that for
the same PGA, the earthquake records in WUS will have
larger PGV, therefore inducing larger displacements in the
structure.
5.2.6 Correlation between PGV and S1,
PGA and M
Several correlations between PGV and other ground mo-
tion parameters such as S1, PGA, and M were developed dur-
ing this study. After reviewing recent publications related to
this subject, a revised form of a PGV correlation suggested by
Abrahamson (2005) for the estimation of PGV from spectral
acceleration at one second (S1) was selected for use, as dis-
cussed in Section 5.3.
It is expected that in the future, USGS will publish recom-
mended PGV values for different locations nationwide. In that
case the S1-PGV correlation will be replaced in favor of design
PGV values, and the designers can use Newmark displace-
ment correlations directly using the USGS-recommended
PGV values.
Figure 5-7. Strong motion information database
5.2.7 Newmark Sliding Block
model.
Displacement Correlations
Various researchers have proposed different correlations
information database, and Table 5-4 gives a description of each for predicting the permanent displacement of earth structures
field in the Access database. The developed database can be used subjected to seismic loading. A summary and comparison of
to efficiently explore correlations between different record char- some of these correlations can be found in a paper by Cai and
acteristics. It also can be used to prepare data sets required for Bathurst (1996). The majority of these correlations are based
various statistical analyses. on the results of direct Newmark sliding block analyses on a
set of strong motion records.
Martin and Qiu (1994) used the following general form for
5.2.5 Spectral Acceleration Characteristics
estimation of Newmark displacement:
To compare strong motion records from different re-
d = C ( k y kmax ) (1 - ky kmax ) Aa 3V a 4 M a 5
a1 a2
gion, magnitude, and soil type bins, the normalized spec- (5-1)
tral acceleration and normalized relative density graphs are
plotted for each bin. The average spectrum for each region- Using a database of earthquake records with a magnitude
site condition for different magnitude ranges was calcu- range between 6.0 and 7.5, published by Hynes and Franklin
lated. The average normalized spectra are presented in (1984), Martin and Qiu concluded that the correlation with M
Figures 5-8 and 5-9. (magnitude) is negligible. The following simplified equation
Results in Figures 5-8 and 5-9 show the following trends: was proposed by Martin and Qiu and adopted in NCHRP
12-49 Project:
· Records with higher magnitudes generally have higher am-
d = 6.82 ( k y kmax ) (1 - ky kmax )
-0.55 5.08
A -0.86V -0.8
86 M 1.66 (5-2)
plitude in the long-period range.
· Records for WUS and CEUS generally have different spec- where
tral shapes. WUS records have higher normalized ampli- d = permanent displacement in inches,
tudes in lower frequency (long-period) ranges, while CEUS ky = yield acceleration,
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Table 5-4. Description of different fields in the access ground motion database.
Table Field Description
INFOTAB NO Earthquake event number
INFOTAB EARTHQUAKE Earthquake event name
INFOTAB YEAR Event year
INFOTAB MODY Event date
INFOTAB HRMN Event time
INFOTAB MAG Earthquake magnitude
INFOTAB OWN Station owner
INFOTAB STNO Station number
INFOTAB STATION Station name
INFOTAB DIST Closest distance from source
INFOTAB GEOM Geomatrix site classification code
INFOTAB USGS USGS site classification code
INFOTAB HP Filter corner frequency, high
INFOTAB LP Filter corner frequency, low
INFOTAB PGA Peak ground acceleration
INFOTAB PGV Peak ground velocity
INFOTAB PGD Peak ground displacement
INFOTAB DUR Duration
INFOTAB FILENAME Record file name
INFOTAB PAA1S Pseudo spectral acceleration at 1 second
INFOTAB PRV1S Pseudo relative velocity at 1 second
INFOTAB RD1S Relative displacement at 1 second
INFOTAB PAAMAX Peak pseudo spectral acceleration
INFOTAB PRVMAX Peak pseudo relative velocity
INFOTAB RDMAX Peak relative displacement
INFOTAB DUR95 5%-95% Arias intensity duration
INFOTAB REGION Region (WUS or CEUS)
INFOTAB SITE Site type (Soil/Rock)
NEWMARK FILENAME Record file name
NEWMARK REGION Region (WUS or CEUS)
NEWMARK SITE Site type (Soil/Rock)
NEWMARK DIR Record direction (horizontal/vertical)
NEWMARK MAG Earthquake magnitude
NEWMARK PGA Peak ground acceleration
NEWMARK KYMAX ky/kmax (ratio of yield acceleration to PGA)
NEWMARK DISP Calculated permanent (Newmark) displacement
Note: Rock/Soil Definitions A and B for rock, C, D and E for soil based on NEHRP classification.
kmax = the maximum seismic acceleration in the sliding block, log ( d ) = b0 + b1 log ( k y kmax ) + b2 log (1 - k y kmax )
A = peak ground acceleration (in/sec2), and
+ b3 log ( kmax ) + b4 log ( PGV ) (5-3)
V = peak ground velocity (in/sec).
Using a logarithmic transformation of the data helped to
A correlation based on Equation (5-2), but in logarithmic stabilize the variance of residuals and normalize the variables,
form, was used for estimation of Newmark displacement hence improving the correlation in the entire range of the
from peak ground acceleration and peak ground velocity. parameters.
Writing Equation (5-2) in logarithmic form resulted in the The coefficients for Equation (5-3) were estimated using
following equation: regression analysis. The permanent displacement data from
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Figure 5-8. Average normalized spectral acceleration for rock
records.
Figure 5-9. Average normalized spectral acceleration for soil
records.
