Integration of site condition information using geographic information system for seismic risk reduction for bridge network

The seismic risk associated with bridges is a function of the structural vulnerabilities and geological conditions at the bridge site. Geographic Information Systems (GIS) allow to integrate spatial information, such as seismic attenuation or local amplification, into ad-hoc information on the structural characteristics of bridges, thereby increasing knowledge on the seismic risk to which a bridge network is exposed. The aim of this study is to develop a scale of susceptibility to the amplification effect by gathering available data on geographic information system platforms. Among other things, this information includes the thickness of the quaternary deposit and surficial geology, complemented with ambient noise measurements. The region of study, the Saint Lawrence Valley, covers an area measuring 32,000 km², extending from Quebec City in the north to the US border in the south, and includes approximately 5000 bridges and overpasses. The highest susceptibility levels in the present study are associated with colluvial, alluvial and marine deposits. The proposed susceptibility scale is to be used for a bridge network, and can be integrated into existing seismic evaluation scoring procedures. It contributes to seismic risk reduction for bridge and overpass networks by improving available assessment procedures for prioritising mitigation strategies, emergency planning and post-earthquake interventions.