Distortional Fatigue Cracking is the Culpritin the Mystery of the McNally BridgeStringer Cracking

摘要

The stringer cracks that developed on the McNally Bridge may not be quite as mysterious as Stonehenge or as famous as crop circles, but the somewhat odd circumstances surrounding the development of hese cracks created a bit of a mystery for Pennsylvania engineers.Why does a bridge that has experienced an estimated 9.6 million fatigue cycles without any significant stringer cracks suddenly develop many cracks during a short, six-month rehabilitation project? This ?mystery? was examined by the Pittsburgh office of HDR and engineers from the Pennsylvania Department of Transportation District 9-0.