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Seismic Fragility Modeling of Structures

A cornerstone of Dr. Padgett’s research is vulnerability, or fragility, modeling of structures under earthquake loading.  In addition to bridges which comprise a primary system of interest in her work, Padgett’s seismic vulnerability modeling research extends to other structural infrastructure including recent or ongoing studies on low ductility reinforced concrete buildings, retrofitted steel buildings, concrete gravity dams, and dry cask structures. Her work has provided fragility models for a range of bridge types and design details, addressing infrastructure characteristic of the Central and Eastern United States, the state of California, and Eastern Canada.  This work addresses gaps in transportation infrastructure risk assessment and supports post-earthquake response.  For example, the California Department of Transportation aims to integrate these models in their ShakeCast platform to deploy inspectors after an earthquake, while priority bridges for retrofit are identified for the Ministry of Transportation in Quebec based on the vulnerability assessment outcomes.  Padgett’s research addresses key questions surrounding seismic reliability assessment, including the role of parameter uncertainty, the selection of ground motion intensity measures used to condition seismic fragility models, and the impact of alternative retrofits, design details and site conditions on seismic performance.  The concept of multidimensional fragilities is also put forward which offer distinct advantages over traditional fragility models since they can be applied with improved precision across a region.  Along this theme, new frameworks are also developed for improving seismic fragility models through the introduction of field measurement data or for using these models to prioritizing seismic retrofits and upgrades.

Low Ductility Concrete BuildingsConcrete Gravity Dam Concrete Gravity Dam

Time Dependent Fragility Example