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From page 61...
... 61   7.1 General A numerical modeling program starts with a preparation process in which (i) the dimensionality of the simulations (1D, 2D, 3D, or some combination thereof)
From page 62...
... 62 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines The first (i.e., leftmost) soil column shown in Figure 7-1 was evaluated as two case histories, each with a different set of recorded acceleration histories.
From page 63...
... Figure 7-1. Schematic representation of case histories evaluated in this study.
From page 64...
... 64 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines supplemented with grain size distributions for the liquefiable sands shown in Figure 4-2, and information for the WLA site shown in Figure 4-4 (PWP response in the 1987 Superstition Hills earthquake) , Figure 6-3 (updated soil profile at the WLA site)
From page 65...
... Numerical Modeling Program 65   excess PWP response is very good. This mismatch in agreements is typical.
From page 66...
... 66 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines After adjusting several parameters of the generic DS set in a trial-and-error process, relatively good agreement between measured and calculated excess PWP was achieved. This is shown in Figure 7-4, which compares recorded and calculated excess PWP response for the subject TI silty sand.
From page 67...
... Numerical Modeling Program 67   (a)
From page 68...
... 68 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines proceeds with the next calibration/validation step, as explained in the next subsection. If the spectral responses do not match, then additional review of the model, with adjustments and elimination of errors, is required.
From page 69...
... Numerical Modeling Program 69   SRA model(s)
From page 70...
... 70 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines Step 3 – Run ESA with Excess PWP Dissipation If the expected trends in the results of the ESA are identifiable, ESA is valid and ready for the next step (i.e., for this step)
From page 71...
... Numerical Modeling Program 71   7.3.2 Ground Surface Response The results of numerical modeling with multiple software programs and CMs are presented in Appendices E-1 through E-5. Review of this information indicates that a relatively good agreement between recorded and calculated response has been achieved for all software and CMs considered, at least in terms of acceleration response at the ground surface.
From page 72...
... 72 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines (e) Port Island, Japan (f)
From page 73...
... Numerical Modeling Program 73   in an abbreviated form in the figure insets. The response presentation is in the form of recorded and calculated acceleration histories.
From page 74...
... 74 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines (a) WLA Site (Original)
From page 75...
... Numerical Modeling Program 75   The impacts of sand boiling and ground surface cracking on site response are especially notable at the WLA site in the 1987 M 6.6 Superstition Hills earthquake. Sudden drops in the normalized PWP history of piezometer P5 (the piezometer closest to the ground surface, just below the WLA site clay crust)
From page 76...
... 76 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines In all cases, recorded and calculated spectra agree the best43 at spectral periods beyond 3.0  s. However, agreement at periods longer than 3.0  s, which typically corresponds to 1.5 times the softened site period (Stewart, 2022b)
From page 77...
... Numerical Modeling Program 77   by approximately 50% at the Port Island site in the M 6.9 Hyogo-Ken Nanbu earthquake, and by approximately 50% in the centrifuge experiment. The difference between TSA and ESA spectral response is also notable in the response of the WLA site in the M 4.9 Hovley earthquake (peak ru = 0.6)
From page 78...
... 78 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines Initially, no excess PWP record was available for the WLA site in the 1987 M 6.2 Elmore Ranch earthquake. However, as shown in Figure 6-14, for this case history, there is relatively good agreement between recorded ground surface spectrum and its centrifuge experiment counterpart.
From page 79...
... Numerical Modeling Program 79   As discussed in Section 4.4.7 and further in Section 7.2.1, field case histories with excess PWP recorded within soil profile are rare. PWP records from the only case that liquefied (i.e., WLA site in the 1987 M 6.6 Superstition Hills earthquake)
From page 80...
... 80 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines (a) M 6.6 Superstition Hills Earthquake (b)
From page 81...
... Numerical Modeling Program 81   (c) Program 3 (UBCSAND)
From page 82...
... 82 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines layer. In the 1987 Superstition Hills event, the WLA site liquefied for the first time in its history.
From page 83...
... Numerical Modeling Program 83   strain reaches a similar value. While the stress–strain loops shown in Figures 7-13(b)
From page 84...
... 84 Seismic Site Response Analysis with Pore Water Pressure Generation: Guidelines Two field case histories at the original WLA site were considered. They are both based on the same soil profile and the same sets of material properties but are shaken by different motions representative of different earthquakes in the vicinity of the site.

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