To appropriately evaluate bridge performance during an earthquake and perform risk assessments, quantitative seismic assessment criteria is desired. Existing seismic risk assessment limit state information, such as the slight, moderate, extensive and complete seismic assessment damage classification levels from the FEMA Hazards U.S. MultiHazard (HAZUS-MH) loss assessment package, is largely qualitative. This paper will discuss ongoing research examining quantitative seismic limit states for one particular class of bridges that has received limited seismic response research attention; curved steel I-girder bridges. Limit states are discussed for key components in the structural system and preliminary findings are presented for a three-span continuous curved steel bridge in Pennsylvania. Seismic response is examined through numerical time history analyses and possible failure mechanisms are studied and assessed.