Center for Transportation Studies, University of Minnesota
With bridge infrastructure in Minnesota aging, advancing techniques for ensuring bridge safety is a fundamental
goal of the Minnesota Department of Transportation (MnDOT). Developing health monitoring systems for
fracture-critical bridges is an essential objective in meeting the stated goal. This report documents the
implementation of two, 16-sensor, acoustic emission monitoring systems in one of the tie girders of the Cedar
Avenue Bridge, which is a fracture-critical tied arch bridge spanning the Minnesota River between Bloomington
and Eagan, MN. The goal of the project is to develop a process for using acoustic emission technology to monitor
one of the girders of the bridge while continuously collecting data from the monitoring systems. Given the cost of
acoustic emission sensing equipment, an approach was adopted to space the sensors as widely as possible. Fracture
tests were conducted on a specimen acoustically connected to the bridge to simulate fracture in a bridge member.
Sets of criteria were developed to differentiate between acoustic emission data collected during fracture and
ambient bridge (i.e. AE noise) data. The sets of criteria were applied to fracture test data and AE noise data to
determine the validity of the criteria. For each criteria set, a period of Cedar Avenue Bridge monitoring data was
analyzed. The results of the analysis of each period showed that the criteria could differentiate between the bridge
AE noise data and the fracture test data. The AE noise data never met all of the criteria in the set, whereas all
criteria were met during each of the applicable fracture tests.
Tillmann, Anton S.; Schultz, Arturo E.; Campos, Javier E..
Protocols and Criteria for Acoustic Emission Monitoring of Fracture-Critical Steel Bridges.
Center for Transportation Studies, University of Minnesota.
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