Probabilistic Seismic Assessment of Transportation Infrastructures Emphasizing on Box-Girder Concrete Bridges Considering Multi-Support Excitation

Earthquake ground motions may vary significantly at multiple supports of long structures such as highway bridges and dams, due to the incoherence, wave-passage, and site-response effects. Therefore, it is expected that seismic behavior of this type of structures would be strongly affected by the changes caused by the motion of the earthquake along the length of the structure. To investigate the seismic vulnerability of these bridges, fragility analysis is performed using spatially variable ground motions. To achieve this aim, this study chooses a set of 70 box-girder bridges considering mechanical and geometrical uncertainties and creates a numerical model of the bridges in OpenSEES software, which can account for the inelastic response of its multiple components. These models are assessed using two scenario of applying the ground motion, uniform and multi-support excitation. The results show that the fragility of these bridges increases with decreasing deck radius by more than 50% (depending on damage level and deck radius) and also with non-flexibility considerations, component vulnerability and bridge system more than 10% is more than a uniform excitation.