Browsing by Subject "Fatigue tests"

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    Innovative Technologies for Lifetime Extension of an Aging Inventory of Vulnerable Bridges
    (Center for Transportation Studies, University of Minnesota, 2011-12) Gastineau, Andrew; Wojtkiewicz, Steven; Schultz, Arturo
    This report refines a response modification framework, previously developed by the authors, which combines technological developments in the fields of control systems, health monitoring, and bridge engineering to increase bridge safety. To enhance the modification framework, the numerical bridge model is refined and additional modification apparatuses are added to the numerical model to further develop and confirm the advantages of the response modification approach. A parameter study of the modification apparatus characteristics is carried out to optimize member sizes and modification device characteristics. Finally, a frequency response analysis is carried out to investigate the use of a semi-active system within the scope of the response modification framework.
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    Protocols and Criteria for Acoustic Emission Monitoring of Fracture-Critical Steel Bridges
    (Center for Transportation Studies, University of Minnesota, 2015-06) Tillmann, Anton S.; Schultz, Arturo E.; Campos, Javier E.
    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.