Date of Award

Winter 2011

Project Type


Program or Major

Civil Engineering

Degree Name

Master of Science

First Advisor

Erin Bell


Over 600,000 bridges are currently in service in the United States; one in three is considered either functionally obsolete or structurally deficient. The Federal Highway Administration defines structurally deficient bridge as one with a condition rating less than four on a scale from zero to nine. If a bridge is considered structurally deficient a load rating is determined. A load rating factor indicates the quantity of design live load that can be safely applied to the bridge. Rating factors are often the result of visual inspections and an analytical protocol that accounts for the effects that dead and live loads have on individual structural elements. To more accurately measure these effects there is a need for an easily deployable and objective measurement of bridge performance and condition. Digital image correlation has the potential to be a cost effective technique for collecting displacement measurements at an in-service bridge structure.

This thesis develops rating factors for a recently constructed 3-span steel girder bridge using five different methods. Methods include load and resistance factor rating, load factor rating, allowable stress rating, a rating based on a structural model created in CSiBridgeRTM, and a rating based on experimental displacement results using digital image correlation. The resulting load rating factors are compared and discussed.