Development of a relative displacement sensor for structural health monitoring

This paper presents the structure, design principle, features and calibration of a developed relative displacement sensor for structural health monitoring. Relative displacement is measured from four strain gauges stuck on a square component connecting two pads, which are used to fix the sensor on the testing structure. The output voltage due to the shear distortion is calculated based on the principle of Wheatstone bridge circuit. The design of the sensor ensures that there are no voltage outputs for the tension, compression, bending and torsion effects. The developed relative displacement sensor is used to monitor the conditions of shear connectors in a composite bridge. The sensitive radius of the sensor to detect the deterioration of shear connectors is investigated. The developed sensor is easy to be installed on structures to detect conditions