Stochastic Risk Assessment of Railway Masonry Arch Bridges in Seismic Prone Areas in Portugal

Risk-based methodologies for analyzing transportation assets have been employed to ensure good performance and long-term safety. Failure of transportation structures leads to major economic consequences, often due to the uncertainties associated with these structures and the effects of unexpected extreme events. Generally, risk is described by hazard intensity, vulnerability, and consequences related to the probability of a given hazard to occur, the susceptibility of a system to be affected by said hazard, and the quantification of the effects, respectively. In Portugal, large masonry arch bridges (MABs) were built during the railway expansion to improve the national network. These structures are expected to continue operating as a crucial part of the railway network without elevated maintenance costs. The present research presents a risk analysis of two of the largest masonry arch bridges built during this period. A risk index is computed based on the combination of code-based hazard curves, seismic fragility curves, and direct consequences. The risk assessment considers material uncertainties, damage states, and peak ground acceleration as the seismic intensity measure. The resulting risk curves provide useful information for prioritizing assets' interventions and taking preventive actions to maintain the desired performance of the railway system.

Keywords: Seismic vulnerability curves, Railway networks, Parameter uncertainty, Asset management.