DAMAGE IDENTIFICATION WITH SENSOR PLACEMENT AND REFERENCE FREQUENCY CHOSEN BASED ON THEORETICAL ERRORS

Abstract

This paper presents a vibration-based damage identification technique for structures using Fourier amplitudes of acceleration responses generated by ground shaking. The proposed damage identification technique estimates structural damage by solving a simultaneous equation. This simultaneous equation is derived from the equation of motion of the structure before and after damage and composed by structural parameters of the intact state, such as mass, damping and stiffness, and measured Fourier amplitudes of the damaged state. Questions as to where to put sensors and Fourier amplitudes at which reference frequency should be used are unsettled. Since there always exist modeling and measurement errors, and since identification accuracy depends on the sensor placement and reference frequency, determination method of the sensor placement and reference frequency giving better accuracy is important. Therefore, the determination method based on theoretical error of the simultaneous equation is also proposed in this study. In the proposed method, the sensor placement and reference frequency generating small condition number of the coefficient matrix of the simultaneous equation is recommended. The validity of the damage identification technique and determination method is confirmed through experiment on a cantilever beam.