Semi-Active Base-Isolation System by MR Damper Utilizing Optimal Regulator Theory

IEEJ Transactions Elec Engng

Tomishi

Sato

et al. 2011

We have developed a novel sensor that enables us to measure the relative story displacement of a building structure in real time. This lateral displacement sensor (LDS) is composed of a light‐emitting diode (LED) array, which is fixed on the ceiling, and a position‐sensitive detector (PSD) unit, which is placed on the floor. We optimized the LDS to achieve high accuracy in lateral displacement measurement. The accuracy was evaluated to be 60 µm by conducting shaking table tests. Two LDSs were implemented in an actual building equipped with an active variable stiffness (AVS) system, and the building was vibrated with seismic waveforms by an exciter placed on the rooftop. The seismic displacement of the second floor relative to the first floor was measured using the LDS. Furthermore, the inclination angle of the second floor could be measured using the LDS during the seismic vibration. Using the AVS system, we realized the residual displacement of the second floor without inducing damage to the building, and succeeded in real‐time residual displacement measurement for the first time. These results indicate that the LDS is useful for the health diagnosis of a building structure. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Section: Introductionmentioning

confidence: 99%

Development of lateral displacement sensor for real‐time detection of structural damage

IEEJ Transactions Elec Engng

Tomishi

Sato

et al. 2011

“…These instruments, however, are not necessarily suitable for the case of seismic displacement measurement. When employed to measure the lateral displacement of a structure relative to the base ground, they have to be set at some kind of tower of a perfect rigid body which exhibits exactly the same movement as the ground at any point of place in the longitudinal direction at any point in time [7][8][9]. However, it would be impossible to construct such a fullscale rigid body tower standing by the structure.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study on Relative Displacement Sensing Using Phototransistor Array for Building Structures

Kanekawa

IEEJ Transactions Elec Engng

Sato

et al. 2010

We propose a novel sensor for directly measuring the relative displacement of a building structure. The sensor is composed of a laser light source and a phototransistor (PT) array. The PT array is immobilized on the floor together with a photo scattering plate made of glass, whereas the laser light source is separately immobilized on the ceiling. The photo scattering plate is placed in front of the PT array and distributes the laser beam on the multiple PTs. The relative displacement between the ceiling and the floor is estimated by the distribution of the PT output voltages, and the displacement is estimated with a resolution finer than the interval between the PTs. The accuracy of the relative displacement sensor (RDS) is experimentally assessed by conducting a shaking table test exhibiting several waves from harmonic sinusoidal waves to real seismic waves. We discuss the feasibility of real-time monitoring system utilizing this sensor. 

“…A range finder allows for displacement sensing along the longitudinal direction. However, these instruments are not necessarily suitable for the case of seismic displacement measurement inside a building because they are required to be arranged on a fixed point of a gigantic rigid body (Hiwatashi et al, 2003). Displacement measured using a GPS suffers from poor resolution (Yoshida et al, 2003).…”

Section: Introductionmentioning

confidence: 99%

Experimental study on lateral displacement measurement using air-coupled ultrasound transducers

Mechanical Engineering Journal

Matsumoto

Ihara

2015

We propose a novel measurement method for directly measuring the lateral displacement of structures by using air-coupled ultrasound transducers. The normally-distributed far field of an ultrasound transducer in a lateral direction is taken advantage of for the purposes of measuring lateral displacement. The measurement system is composed of three flat-type air-coupled ultrasound transducers and a steel wire as a target. The ultrasound transducers are immobilized at a fixed point, whereas the steel wire is separately arranged on the opposite side. When the steel wire is displaced laterally, the lateral displacement is calculated utilizing the intensity ratio of the reflected ultrasound waves. The accuracy of the lateral displacement measurement is experimentally assessed to be within ± 0.5 mm and the feasibility of the measurement system is discussed. The results show that a developed displacement measurement method will be usable in the field of structural health monitoring due to its accuracy and wide measurement range through the use of several ultrasound transducers.