Bridges

As with other similar bridges throughout the world, the steel box girder spans of Melbourne’s West Gate Bridge have, in recent years, exhibited an increasing incidence of fatigue cracking.

This paper is concerned with the potential for fatigue cracking of the welded connection between the deck plate and the supporting trough stiffeners of the orthotropic deck. Finite element analysis has been used to determine the stress distribution within the joint due to wheel loads, identify where fatigue cracks are likely and estimate the fatigue life of the detail. The number and magnitude of the load cycles used for the estimation of fatigue life were determined from strain measurements on the deck plate and troughs.

The paper provides details of the investigations, inspection methods used to check for fatigue cracks, including phased array ultrasonic testing, and how the findings from the finite element analysis have been used to manage the NDT inspections of the weld detail.