## 5 Discussion and Conclusions  
This paper establishes a numerical model of a seismic isolation continuous beam bridge, systematically analyzing the uncertainties based on both the seismic isolation device system and the non-isolated system. This study established a numerical model of a continuous beam bridge with seismic isolation. The uncertainties associated with the model were systematically analyzed within the frameworks of the seismic isolation device system and the non-isolated system, taking into account targeted uncertainty factors in accordance with established design principles for seismic isolation continuous beam bridges. Additionally, the analysis included a discussion on the uncertainties and their impact concerning the capacity threshold of shear pins that support the strength of the bridge's bearing system during normal operational phases. The calculation results are used to create tornado diagrams and variance contribution graphs derived from first- and second-order moment methods. A sensitivity analysis of the 16 model uncertainties was performed under four levels of earthquake intensity, allowing for the identification of factors that significantly influence the seismic response of the bridge structure. The following conclusions were reached:  
1. The parameter sensitivity analysis results differ somewhat between the first-order second-moment method and the tornado diagram method. This discrepancy arises because the first-order second-moment method retains only linear terms in its derivation, making it best suited for scenarios where changes in seismic response random variables are linear or exhibit weak nonlinearity. However, the differences in the results of the two methods primarily affect the ranking of less influential random variables and do not alter the selection of significant random variables. 2. The uncertainty factors identified as having a substantial impact on the seismic response of the bridge structure include the specific weight coefficient, bearing friction coefficient, clay ultimate resistance, damping ratio, elastic modulus, clay ultimate deformation, and yield strength of the capacity design bearing. Other factors can be treated as deterministic based on specific conditions. 3. The selection results across the four levels of earthquake intensity are generally consistent. Notably, the yield strength of the capacity design bearing is a significant factor unique to the L1 effect. Under the L4 effect, the impact of the elastic modulus E slightly decreases compared to L1-L3 scenarios, moving beyond the threshold of 10% in the variance contribution ranking. Conversely, the influence of the yield strength of \begin{table}
\begin{tabular}{c} \(\mu_{\text{bearing}}\), \(A_{\text{up}}\), \(P_{\text{ult,clay}}\), \(\zeta\), \(y_{\text{50,clay}}\) \\ \end{tabular} \\ \hline \end{tabular}
\end{table} 
Table 5: Parameter sensitivity analysis results under four ground motion intensities. the steel damping device slightly increases but remains relatively minor. The selection results showed minimal changes before and after considering collision effects. 4. When modeling and analyzing seismic responses for isolation bridges, it is crucial to carefully consider the significant uncertainty factors that can affect the seismic performance of the bridge structure to ensure the accuracy of calculations. This is particularly important for often overlooked parameters, such as the melting force of isolation bearings. In examining the impact of uncertainty on the seismic demand analysis of bridges, this study assumes the independence of various uncertainty parameters. However, it is essential to recognize that these parameters may exhibit certain correlations in reality. Future research should further explore the influence of correlations among uncertainty parameters on the seismic demand analysis of bridges. Conceptualization, J.W. ; methodology, R.W. ; software, R.W. ; validation, M.L. and J.W. ; formal analysis, M.L. ; investigation, R.W. ; resources, M.L. ; data curation, J.W.