Contact Free Sensor to Monitor Prestressing Anchors in Geotechnical Structures-Paper

Paper

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The paper presents DYNA Force, an elasto-magnetic sensor system for monitoring forces in prestressing steel used in geotechnical anchors and structures. The sensor magnetizes the steel through a primary coil and measures its magnetic response with a sensing coil. Because this response changes with steel stress, a calibrated readout unit converts it into a force measurement; an embedded thermistor provides temperature compensation.<br /><br />Sensors are installed around steel tendons or bars before stressing. They can monitor bare, coated, galvanized, or sheathed steel in bonded or unbonded, grouted or ungrouted sections. The system supports manual, automated, and remote readings, with multiplexers, cables, and communications equipment enabling continuous data collection.<br /><br />The paper describes applications in more than 80 projects, including retaining walls, bridge abutments, dams, and landslide stabilization. Case studies report long-term anchor monitoring, remote readings during dam excavation, and automated measurements at bridge and highway projects. Sensors also helped identify load-transfer behavior along anchor bond lengths and assess potential debonding.<br /><br />The authors conclude that the system offers accurate, durable, cost-effective monitoring with straightforward installation. It has no moving parts, requires no maintenance, and is expected to last as long as the surrounding structure. Its ability to provide ongoing or remote force data can help owners and engineers evaluate structural performance and identify potential problems.

Keywords

DYNA Force

elasto-magnetic sensor

prestressing steel

force monitoring

geotechnical anchors

magnetic response

temperature compensation

remote readings

bridge and dam monitoring

anchor load transfer