An online platform for bridge-specific fragility analysis of as-built and retrofitted bridges

Bridges are the most critical and usually the most vulnerable structural component of a road network exposed to various hazards. Damage due to recent earthquakes worldwide highlighted the substantial direct and indirect financial losses related to partial or total collapse of critical bridge components and pointed to the need for reliable assessment of their seismic performance. This paper presents a ‘toolkit’ developed for bridge-specific fragility analysis of bridges; it is implemented on a “two-track” online platform, including ad-hoc developed software for online bridge-specific fragility curve derivation, as well as the option to select an appropriate set of generic fragility curves from a database including a broad range of bridge classes. Three alternative options for the estimation of component-specific limit state thresholds are provided; selection from extensive lists with available thresholds for piers, bearings and abutments, and calculation of limit state thresholds for as-built and retrofitted piers based on (a) closed-form relationships, or (b) inelastic pushover analysis and capacity assessment of a parametrically defined pier model (carried out online). Details regarding the software developed, the methodology for bridge-specific fragility curves, and all critical features are presented and discussed herein. The application of the online software is illustrated through two case studies involving the derivation of fragility curves for bridges with different structural systems and properties.