Study on Steel Tendon Positioning in Grouting Duct Based on Capacitive Sensor
Wenlong Tao1, Jiahe Li1, Nan Li1*
1Northwestern Polytechnical University, University, Xi’an, China
Grouting quality evaluation is very important to the construction building of post-tensioned duct units. The steel tendon is a key part of the post-tensioned duct. The positioning of the steel tendon in the grouting duct is the prerequisite of damage detection and quality evaluation. A dual-electrode coplanar capacitive sensor was designed according to our previous researches to complete this task. The performance of the designed sensor was evaluated by simulation and experiments, respectively. The results show that the proposed method is feasible and valuable for positioning steel tendons in grouting ducts. At the same time, some interesting phenomena were observed from the practical experiments. A series of models were designed to further analyze these interesting differences between the results of simulation and experiments. For an 80mm inner-diameter grouting duct with a 16mm diameter steel tendon inside, the effective positioning area is limited to the outer zone (l10mm). The inner zone (l<10mm) close to the center area of the grouting duct is a non-sensitive area. The biggest difference between simulations and experiments is the angle positioning of the steel tendon, the interesting phenomena were affected by sensor design (mainly depends on the sensor structure), different material properties, and environmental factors. However, the difference between simulations and experiments does not affect the conclusion, i.e. the designed capacitive sensor can be used for steel tendon positioning in grouting duct.
Keywords: Non-destructive testing, capacitive sensor, grouting duct detection, positioning.
Industrial Application: Architecture, buildings and bridges.
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