Prof. Connor Releases Report on Evaluation Recommendations for Fracture Critical Built-up Steel Members

By law, this family of bridges are required to be inspected using costly hands-on techniques to help ensure any defects are found before they become a problem. Once a bridge is labeled “fracture critical”, there is a lifetime requirement of more rigorous in-service inspections. However, these bridges have historically performed surprisingly well, even when such a member has failed.

Robert Connor, Professor and Director of CAI and S-BRITE, and colleagues developed rational engineering-based methods to evaluate the internal redundancy of steel members comprised of multiple components through transportation pooled fund project TPF-5(253).  The pooled fund project was led by the Indiana Department of Transportation with participation from Iowa, Minnesota, New York, Oregon, Wisconsin, Wyoming, Army Corps of Engineers and FHWA.  Prof. Connor’s Guide Specifications for Internal Redundancy of Mechanically-fastened Built-up Steel Members, was recently adopted by AASHTO in June of 2018.  A major component of the specification provides strategies to set inspection scope and interval that is tied to engineering performance and not simply based on the calendar. 

Anne Rearick, INDOT Director of Bridge Management, indicates “that this guidance will assist us in making bridge specific decisions that will allow for better utilization of limited inspection resources.” According to Mr. Tom Macioce, Chair of the AASHTO Steel Bridge Design Committee (T-14) and Chief Bridge Engineer of the Pennsylvania DOT, “At the national level, a significant step in addressing the ongoing debate on how to evaluate built up members for internal redundancy has occurred due to this research project.  The end result of the completed research is a new AASHTO Guide Specifications for Internal Redundancy of Mechanically-fastened Built-up Steel Members that is theoretically sound while at same time is practical for engineers to use.”