Seismic Performance and Damage Assessment of Transportation Systems During the 2025 Myanmar Earthquake (M7.9)

The M7.9 Myanmar earthquake on March 28, 2025, caused extensive damage to the local transportation network. Through a 14‐day field investigation in the affected areas, a joint Sino–Myanmar survey team established a seismic damage database encompassing highway and railway bridges. To address the scarcity of near‐fault strong‐motion records, simulated ground motion fields were adopted to evaluate structural seismic demands. Based on these ground motion fields, the failure mechanisms of 18 damaged bridges were analyzed, and regional statistical comparisons were conducted using the spectral element method. The investigation results indicate that the bridge damage direction is governed by the relative dominance between the fling‐step effect and the rupture directivity effect. Furthermore, strong ground motions at soft soil sites in river valleys are prone to inducing soil liquefaction and lateral spreading. Statistical fragility analyses demonstrate that the median peak ground accelerations for all damage states in highway bridges are significantly higher than the actual demands, with damage primarily concentrated in bearing sliding, girder collisions, and pier plastic hinging. In contrast, the median peak ground acceleration for moderate damage in older railway bridges is merely 0.48 g, highlighting extreme systemic vulnerability characterized by masonry material degradation and universal damage to steel truss girders. The research findings provide a scientific basis for the seismic retrofitting of Myanmar's transportation network. It is recommended that end cross‐girders and shear connectors be added to steel and concrete composite girder bridges, column jacketing and comprehensive unseating prevention devices be implemented for older bridge piers, strategies for resisting strong shaking and fault rupture be adopted for near‐fault and fault‐crossing routes, and corresponding antiliquefaction engineering designs be implemented in liquefaction‐susceptible areas.