# Estimation of Seismically-Induced Crest Settlement of Earth Core Rockfill Dams
## 4 Crest Settlement Calculations and Correlation with Ground Motion Parameters  
A total of 20 ground motions were selected from the Next Generation Attenuation (NGA-West2) database ([[https://ngawest2.berkeley.edu/](https://ngawest2.berkeley.edu/)]([https://ngawest2.berkeley.edu/](https://ngawest2.berkeley.edu/))) to perform a suite of nonlinear numerical simulations,  
Figure 4: Comparison of measured peak ground acceleration (\(PGA\)) profiles from centrifuge tests and calculated profiles from 2D dynamic simulations. Figure 3: The models of ECRD used for validation. (**a**) Centrifuge model [18] and (**b**) numerical model of ECRD from this investigation. from which empirical correlations between the ground motion parameters (GMs) and the crest settlement were developed. Detailed information regarding the respective ground motions, including _PGA_, peak ground velocity (_PGV_), and moment magnitude (_M_), were provided in the NGA-west2 database. These are summarized in Table 3. All 5% damped acceleration response spectra and the design spectrum of Korea [19] normalized to PGA are shown in Figure 5. The motions were imposed at the bottom of the computational domain, as shown in Figure 1.  
The crest settlements and settlement ratios were calculated from the dynamic analyses. The settlement ratio was defined as the vertical settlement normalized by the height of the dam. It should be noted that this definition was different from that of [PERSON] [1], where the settlement ratio was defined as the vertical settlement at the dam crest (including the settlement of the dam structure and the underlying soil) divided by the height of both the dam and the underlying soil. [PERSON] [1] used this ratio because the respective settlements of the dam structure and the underlying soil could not be separated from the measured crest settlements. Because the settlement of the underlying soil  
Figure 5: Spectrum of 5% damped response of input motions and the design response spectrum of Korea [19] normalized to the _PGA_. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**No.** & **Earthquake Name** & **Station Name** & _PGA(g)_ & _PGV(cm/s)_ & **Magnitude, _M_** \\ \hline
1 & Nahanni, Canada & Nahanni Station \#3 & 0.148 & 6.1 & 6.8 \\
2 & Loma Gilroy, USA & Gilroy Array \#2 & 0.17 & 14.2 & 6.9 \\
3 & Whittier Narrow, USA & Rancho Palos Verdes & 0.186 & 4.6 & 6 \\
4 & San Fernando, USA & Pacoima Dam & 0.209 & 18.9 & 6.6 \\
5 & Northridge, USA & Beverly Hills & 0.217 & 9.8 & 6.7 \\
6 & Kocaeli, Turkey & Arcelik & 0.218 & 17.7 & 7.4 \\
7 & Landers, USA & Yermo Fire & 0.244 & 25.7 & 7.3 \\
8 & Hector, USA & North Palm Spr. & 0.265 & 28.5 & 7.1 \\
9 & Loma Gilroy, USA & Gilroy Array \#3 & 0.357 & 28.6 & 6.9 \\
10 & Parkfield, USA & Parkfield–Cholame & 0.357 & 21.5 & 6.1 \\
11 & El Centro, USA & Imperial Valley Distr. & 0.4 & 37.8 & 6.9 \\
12 & Mammoth Lakes, USA & Long Valley Dam & 0.43 & 23.5 & 6.3 \\
13 & Duzee, Turkey & Bolu & 0.727 & 56.4 & 7.1 \\
14 & Kobe, Japan & Nishi–Akashi & 0.509 & 37.3 & 6.9 \\
15 & Tabas, Iran & Mhud–Bajestan & 0.899 & 55 & 7.8 \\
16 & Chi–chi, Taiwan & Taiwan & 0.057 & 2.3 & 6.2 \\
17 & Tottori, Japan & HYG007 & 0.035 & 1.2 & 6.61 \\
18 & Northridge, USA & Vasquez Rocks Park & 0.15 & 11.1 & 6.69 \\
19 & Morgan Hill, USA & Gilroy Array & 0.069 & 2.7 & 6.19 \\
20 & San Fernando, USA & Pasadena, Old Seismo Lab & 0.095 & 5.8 & 6.61 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Details of input ground motion selected to perform nonlinear dynamic analyses. was highly dependent on the site-specific stratigraphy and also because the foundation soil influenced both the numerator and the denominator, the difference in these definitions may either produce a higher or a lower ratio estimate. In this study, because stiff elastic soil was assumed to underlie the dam, only the calculated settlement in the dam structure was used to calculate the settlement ratio.