# Collapse Potential of an Existing Reinforced Concrete Bridge Structure
## 2 Materials and Methods
### Ground Motions  
The selection and spectral matching of the ground motions to be used for nonlinear time-history analysis play an important role in evaluating the seismic performance of a structure. Ten earthquake ground motion records, obtained from the \"Pacific Earthquake Engineering Research Center (PEER)\" ground motion database [36], with varying magnitudes, peak ground accelerations (PGA), and source distances, were selected in this study to account for the inherent randomness of seismic events. Since the investigated bridge is  
Figure 12: The passive longitudinal response of the backfill soil [34]: (**a**) Force-displacement relationship; (**b**) geometric properties of backwall.  
located on Site Class B, all selected ground motion records were taken among earthquakes recorded at the stations on Site Class B. Soil layers and their amplification effect were not considered since the used records are not on the bedrock but on the stations located on different soil profiles. Therefore, the randomness originating from the soil profiles has also been taken into account in an indirect manner. All of the considered ground motions are summarized in Table 1.  
The selected ground motion records were matched to the target spectrum of the structure using \"Seismomatch 2016\" software [37]. The Turkish Bridge Seismic Design Code [1] requires that this type of bridge must meet the collapse prevention performance level requirements under the effect of an earthquake with a 2% probability of exceedance, in other words, the maximum earthquake. Thus, the target spectrum used for matching is the spectrum of the maximum earthquake. A damping ratio of 5% was applied to each input record. Figure 13 shows the acceleration spectrum of the selected ground motions.  
The amplitudes of the average spectrum of all of the selected records between the periods of 0.2T\({}_{1}\) and 1.5T\({}_{1}\) must be higher than the amplitude of the design spectrum according to the Turkish Bridge Seismic Design Code [1] provisions. As can be seen from Figure 14, this provision is satisfied. T\({}_{1}\) is the period of the dominant mode of the bridge, which is equal to 0.238 s. Figure 14 shows the mean spectrum of the matched ground motion records and the design spectrum.  
\begin{table}
\begin{tabular}{l c c c c c c c c} \hline \hline
**Event** & **Year** & **Station** & **PGA** & **Magnitude** & **Rjb (km)** & **Rrup (km)** & **V\({}_{\textbf{s30}}\) (m/s)** & **Site Class** \\ \hline San Fernando & 1971 & \
\begin{tabular}{c} Cedar Springs, \\ Allen Ranch \\ \end{tabular} & 0.015 & 6.61 & 89.37 & 89.72 & 813.48 & B \\ \hline Tabas, Iran & 1978 & Tabas & 0.86 & 7.35 & 1.79 & 2.05 & 766.77 & B \\ \hline Morgan Hill & 1984 & Gilroy Array \#1 & 0.098 & 6.19 & 14.9 & 14.91 & 1428.14 & B \\ \hline Landers & 1992 & Lucerne & 0.63 & 7.28 & 2.19 & 2.19 & 1369 & B \\ \hline Northridge-01 & 1994 & Vasquez Rocks Park & 0.13 & 6.69 & 23.1 & 23.64 & 996.43 & B \\ \hline Kocaeli, Turkey & 1999 & Gebze & 0.14 & 7.51 & 7.57 & 10.92 & 792 & B \\ \hline Loma Prieta & 1989 & Los Gatos & 0.3 & 6.93 & 3.22 & 5.02 & 1070.34 & B \\ \hline Duzce, Turkey & 1999 & IRIGM 496 & 0.74 & 7.14 & 4.21 & 4.21 & 760 & B \\ \hline \multirow{2}{*}{Parkfield-02, CA} & \multirow{2}{*}{2004} & \multirow{2}{*}{
\begin{tabular}{c} Diablo Canyon \\ Power Plant \\ \end{tabular} } & \multirow{2}{*}{0.0055} & \multirow{2}{*}{6} & \multirow{2}{*}{78.14} & \multirow{2}{*}{78.24} & \multirow{2}{*}{1100} & \multirow{2}{*}{B} \\ \cline{1-1} \cline{5-5}