Bridge Scour Monitoring using Smart Rocks Based on Magnetic Field Interference
In this study, two types of smart rock were proposed to monitor bridge scour effect, including a direction-unknown (DU) smart rock and a direction-known (DK) smart rock. The DU smart rock is a concrete ball containing a cylindrical magnet, and the DK smart rock is also a concrete ball but contains a magnet whose direction is always pointing to the projected direction of the ambient magnetic field (AMF) in the horizontal plane. Based on the theory of magnetic field, the distribution of the magnetic field induced by DU and DK smart rock was derived. Algorithms were developed to localize the position of the two smart rocks under the AMF. Field tests were conducted at a bridge pier, and the intensity and direction of the AMF at the test site were measured by using a magnetometer and a home-made device, respectively. Results showed that presence of steel reinforcement and steel girders in the bridge changed the distribution of the geomagnetic field. The algorithms were able to localize the position of both the DU and the DK smart rocks with satisfied accuracy. Compared with the DU smart rock, the amount of calculation to localize DK smart rock was reduced. However, the measurement error was increased due to the instability of its direction from varying AMF caused by environmental factors such as passing vehicles on the bridge.
Y. Chen et al., "Bridge Scour Monitoring using Smart Rocks Based on Magnetic Field Interference," Smart Materials and Structures, vol. 27, no. 8, Institute of Physics - IOP Publishing, Aug 2018.
The definitive version is available at https://doi.org/10.1088/1361-665X/aacbf9
Civil, Architectural and Environmental Engineering
Keywords and Phrases
Concretes; Electromagnetic field effects; Geomagnetism; Magnetic fields; Magnets; Structural health monitoring; Bridge scour; Cylindrical magnets; Environmental factors; Geomagnetic fields; Magnetic field interference; Noncontact measurements; Steel girder; Steel reinforcements; Rocks; Magnetic field; Non-contact measurement; Smart rock; Structural health monitoring
International Standard Serial Number (ISSN)
Article - Journal
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