The welded steel bridge at the Facility for Accelerated Service Testing has been in service since 1997. With regular monitoring and inspections, the steel bridge continues in service, having accumulated more than 1,800 million gross tons of heavy-axle-load traffic and more than 11 million load cycles. In addition to providing fatigue test results, this bridge provides for evaluation of various repair methods and evaluation of potential technologies for enhanced inspection and condition monitoring. Numerous cracks in the steel bridge at FAST became visible in 1997-1998. Cracks have continued to initiate, often in different areas of the bridge, as indicated in Figure 1. The one common factor is that all of the cracks appear to have initiated at or near a welded connection. This article provides an update to a series of previous progress reports on the fatigue cracks in this bridge.
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