New Technology of Force Monitoring of Post-Tensioning Ground Anchors-Paper

Paper

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The paper presents DYNA Force sensors, which use elasto-magnetic technology to monitor forces in post-tensioned steel and ground anchors. A sensor magnetizes the steel and measures changes in its magnetic response; calibrated readings are converted into direct force measurements. Temperature compensation and steel-specific calibration support accuracy across different steel types and coatings.<br /><br />Sensors are installed around strands or bars before stressing and can monitor tendons in bonded or unbonded, grouted or ungrouted sections. Unlike conventional load cells, they sit within the anchor hole, require no extra bearing-plate space, have no moving parts, need no maintenance, and are designed to last about as long as the surrounding structure. Readings can be collected manually, automatically at set intervals, or remotely.<br /><br />Project examples demonstrate use in retaining walls, dams, bridge abutments, and highway slope stabilization. At Patton Creek, measurements taken after lock-off and during six years of service showed changing anchor forces, possibly linked to nearby road construction. At Willow Island Dam, remote readings from 84 sensors tracked anchor loads during excavation and closely matched hydraulic-jack readings. Other projects used sensors to monitor retaining-wall performance and identify how force transferred along anchor bond lengths.<br /><br />The authors report that the system has been used in more than 80 projects. They conclude that it provides an accurate, practical, and cost-effective way to verify stressing forces and monitor anchors over time, offering owners and engineers useful information for assessing structural performance and reducing the risk of anchor failure.

Keywords

DYNA Force sensors

elasto-magnetic technology

post-tensioned steel

ground anchors

force monitoring

temperature compensation

steel calibration

anchor load measurement

retaining walls

bridge abutments