Sensor Network for Structural Health Monitoring

For assessing condition of a civil structure subjected to earthquakes, it is of great significance to evaluate the structural response to the seismic excitations. In most cases, such evaluation is made based on acceleration measurement. Currently, the acceleration-based measurement is a matter of necessity rather than a matter of choice although more useful information would be expectedly obtained by measuring the displacements.

To make the displacement-based measurement of a building structure, we developed a novel system that enables us to directly measure the relative-story displacement and inclination in real time. The system is composed of light sources immobilized on every ceilings and photosensors immobilized on every floors. The system is integrated by connecting all the light source-photosensor pairs with the local-area network. The system was designed to fulfill following specifications: (i) Real-time, direct measurement of relative-story displacement and inclination, (ii) Measurement range of 100 mm with the accuracy of 0.1 mm, (iii) Sampling rate of 100 Hz for the vibration measurement of up to 20 Hz, (iv) Scalable for multi-point measurements, and (v) Low-costly and small-sized.

This research has started taking advantage of the establishment of Consortium for Nanoelectronics, Information and Communication technology, and Sensor network (NICS) of Waseda University, and is currently promoted through a collaborative work involving Waseda University (Prof. Iwao Ohdomari, Prof. Akira Nishitani, Prof. Shuichi Shoji, and our group) and Kajima Corporation. A Kajima Corporation building that has a seismic isolation structure was equipped with our relative-story displacement sensing system, and the displacements according to the vibrations excited by artificial excitators or by actual earthquakes are carefully investigated.


K.Kanekawa, I.Matsuya, M.Sato, R.Tomishi, M.Takahashi, S.Miura, Y.Suzuki, T.Hatada, R.Katamura, Y.Nitta, T.Tanii, S.Shoji, A.Nishitani, I.Ohdomari: An Experimental Study on Relative Displacement Sensing Using Phototransistor Array for Building Structures, IEEJ Transactions on Electrical and Electronic Engineering 5, 2010, 251.

I.Matsuya, R.Tomishi, M.Sato, K.Kanekawa, Y.Nitta, M.Takahashi, S.Miura, Y.Suzuki, T.Hatada, R.Katamura, T.Tanii, S.Shoji, A.Nishitani, I.Ohdomari: Development of Lateral-Displacement Sensor for Real-Time Detection of Structural Damage, IEEJ Transactions on Electrical and Electronic Engineering, 6, (2011), 266-272.

I.Matsuya, R.Katamura, M.Sato, M.Iba, H.Kondo, K.Kanekawa, M.Takahashi, T.Hatada, Y.Nitta, T.Tanii, S.Shoji, A.Nishitani, I.Ohdomari: Measuring Relative-Story Displacement and Local Inclination Angle Using Multiple Position-Sensitive Detectors, Sensors 10, 2010, 9687-9697.