NJTA owns several steel bridge superstructures that are in service for more than 60 years. Being on strategic commerce route, these bridges are subjected to large Average Daily Truck Traffic (ADTT), with potential for fatigue damage to the bridge superstructure. Recently unique fatigue cracking was discovered in one of the major bridges in the floor beams under the stringers at the deck expansion joints. This fatigue cracking is unique in that the cracks developed in the floor beam top flange-to-floor beam web stiffener welds, either at the weld toes or from the weld root that eventually severed the stiffener-to-flange connection. Given a large number of these connections in the bridge and the unusual cracking mode, determining the root cause is necessary for an appropriate intervention plan and maintaining this structure on a regionally important corridor in a state of good repair.

The intended outcome of the project is to develop knowledgebase that will be incorporated as part of professional training programs on fatigue and fracture of steel bridges. The project will generate a technical brief regarding an unusual cracking mode in aging steel bridge infrastructure. A cost-effective intervention plan is expected to be derived from the analysis results that would be implemented in the bridge.