Monitoring of Fracture Critical Steel Bridges - Phase III

Principal Investigator:

Arturo Schultz, Professor, Civil, Environmental and Geo-Engineering

Project Summary:

With its large inventory of steel bridges, many of which are designated fracture-critical with a variety of problematic details (Lindberg, 2007), MnDOT must be able to select, procure, and operate sensor systems for a small subset of these bridges that require monitoring. In previous phases of this study, the PI developed an acoustic emission monitoring system for a bridge?the Cedar Avenue Bridge (No. 9600) that has shown no evidence of cracking during its life. A major advantage of working with a problem-free bridge is that the risk of missing an important fracture event while the system is being implemented is very low. The major drawback, however, is that the monitoring system is unlikely to be tested with an actual fracture event. In fact, the monitoring system for the Cedar Avenue Bridge has been collecting approximately 150,000 acoustic emission counts per month, but the vast majority of these counts are below the manufacturers threshold for important events. Consequently, this research seeks to develop a monitoring system for a bridge with a somewhat higher potential for future cracking problems, Bridge No. 82815 in Forest Lake. The research will also continue monitoring the Cedar Avenue Bridge using the existing 16-sensor system.

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