Abstract
We propose a novel sensor system for monitoring the structural health of a building. The system optically measures the relative-story displacement during earthquakes for detecting any deformations of building elements. The sensor unit is composed of three position sensitive detectors (PSDs) and lenses capable of measuring the relative-story displacement precisely, even if the PSD unit was inclined in response to the seismic vibration. For verification, laboratory tests were carried out using an Xθ-stage and a shaking table. The static experiment verified that the sensor could measure the local inclination angle as well as the lateral displacement. The dynamic experiment revealed that the accuracy of the sensor was 150 μm in the relative-displacement measurement and 100 μrad in the inclination angle measurement. These results indicate that the proposed sensor system has sufficient accuracy for the measurement of relative-story displacement in response to the seismic vibration.
Highlights
Relative-story displacement measurements have attracted much attention because of their capability of directly monitoring building damage [1,2]
We investigated the resolution, which was the most important performance of the combined position sensitive detectors (PSDs)
The results show that the proposed method can correctly measure the relative-story displacement and the inclination angle of the floor
Summary
Relative-story displacement measurements have attracted much attention because of their capability of directly monitoring building damage [1,2]. A possible solution is to measure the local inclination angle and the torsion angle as well as the relative-story displacement. Such a measurement has already been realized in the image stabilizer of a digital camera by which the captured image is automatically stabilized against unstable handling using an embedded gyro sensor [4]. Gyro sensors do not work in case of seismic vibrations because the frequency of the seismic motion is too low (from DC to 20 Hz), and the inclination angle (approximately 0.001 rad) is too small Park and his group have proposed a method called the partitioning approach that measures the relative-story displacement and the inclination angle of the floor by implementing two video cameras on every floor [5]. The conventional methods are not convenient for the relative-story displacement measurement
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
