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46 the previously mentioned database were used in the regression modified by the Site Class factor for peak ground acceleration analysis. The regression analyses were performed for different (Fpga). The current AASHTO LRFD Bridge Design Specifica- regions (WUS/CEUS) and site conditions (rock/soil), resulting tions define the site-adjusted PGA as As. For this Project kmax in four different correlations. The correlations are presented in is used rather than As to be consistent with the common prac- Equations (5-4) to (5-7). The units in Equations (5-4) to (5-7) tice in geotechnical earthquake engineering of using k as the are displacement (d) in inches, PGA in g, and PGV in in/sec. seismic coefficient during seismic earth pressure and slope WUS-Rock: stability evaluations. log ( d ) = -1.55 - 0.75 log ( k y kmax ) + 3.05 log (1 - k y kmax ) 5.2.8 Comparison Between Correlations -0.76 log ( kmax ) + 1.56 log ( PGV ) (5-4) A comparison between correlations for different regions and with a standard error of 0.22 log10 units. site conditions has been performed. The comparison was car- ried out for two cases, assuming PGV (in/sec) = 30 PGA WUS-Soil: (in/sec2) and PGV (in/sec) = 60 PGA (in/sec2), respectively. log ( d ) = -1.56 - 0.72 log ( k y kmax ) + 3.21 log (1 - k y kmax ) These comparisons are shown in Figures 5-10 through 5-17. The results from these comparisons are summarized as follows: -0.87 log ( kmax ) + 1.62 log ( PGV ) (5-5) with a standard error of 0.22 log10 units. Figures 5-10 and 5-11 show the comparison between rock and soil correlations for WUS region [Equations (5-4) and CEUS-Rock: (5-5)] for PGV = 30 kmax and PGV = 60 kmax, respectively. log ( d ) = -1.31 - 0.93 log ( k y kmax ) + 4.52 log (1 - k y kmax ) Figures 5-12 and 5-13 show the comparison between the rock and soil correlations for CEUS region [Equations (5-6) and -0.46 log ( kmax ) + 1.12 log ( PGV ) (5-6) (5-7)] for PGV = 30 kmax and PGV = 60 kmax, respectively. with a standard error of 0.31 log10 units. Figures 5-14 and 5-15 compare WUS-Rock and CEUS-Rock correlations [Equations (5-4) and (5-6)]. CEUS-Soil: Figures 5-16 and 5-17 show the comparison between log ( d ) = -1.49 - 0.75 log ( k y kmax ) + 3.62 log (1 - k y kmax ) Martin-Qiu correlation and WUS-Rock correlation [Equa- tions (5-2) and (5-4)]. -0.85 log ( kmax ) + 1.61 log ( PGV ) (5-7) with a standard error of 0.23 log10 units. These comparisons show that the CEUS-Rock correlation When using the above equations, the term kmax is the peak results in smaller displacements in comparison to other cor- ground acceleration coefficient (PGA) at the ground surface relations, including the Martin-Qiu correlation. It should be Figure 5-10. Comparison between WUS-Rock and WUS-Soil correlations for PGV = 30 kmax.

OCR for page 46
Figure 5-11. Comparison between WUS-Rock and WUS-Soil correlations for PGV = 60 kmax. Figure 5-12. Comparison between CEUS-Rock and CEUS-Soil correlations for PGV = 30 kmax. Figure 5-13. Comparison between CEUS-Rock and CEUS-Soil correlations for PGV = 60 kmax.