Fracture Resilience and Redundancy of Built-up Steel Girders

Internal member redundancy provides built-up steel girders with the ability to resist total member failure in the event an individual component fails. Anecdotal evidence of in- service performance has historically shown this to be the case in many bridges. However, due to the lack of experimental data, these members are currently required to be inspected as fracture-critical when deemed non-redundant. The full-scale experimental and analytical research program described in this paper provides needed information on parameters that affect the ability of built-up members to arrest a fracture, as well as describing the length of the remaining fatigue life. The results from this study have been used to develop recommended assessment procedures for built- up flexural members when a component has failed. Proposed evaluation guidelines will permit bridges with built-up steel girders where sufficient capacity exists, and the fracture critical designation can be removed, to be inspected using a rational in-service interval and level of detail. Considering the large number of riveted fracture critical bridges in the inventory, both highway and railroad bridge owners will benefit from this research since it allows for implementation of a more rational inspection strategy without compromising safety and reliability. The strategy provides a more integrated approach to inspection that accounts for the probability of detection capabilities, fatigue life, and fracture resilience. Further, new members utilizing high-strength bolted built-up members have the potential to be used without the penalty of being classified as fracture critical in terms of inspection