Structural health monitoring for critical members of civil infrastructures using piezoelectric active sensors

Abstract

Cost-effective and reliable damage detection and health monitoring of critical members are very essential for safe operation of civil infrastructures such as bridges, buildings, power plants, etc. This dissertation addresses several primary software and hardware issues for online structural health monitoring (SHM) techniques for critical members of civil infrastructures using piezoelectric active sensors. The piezoelectric active sensors can provide special features suitable for real-time wireless SHM systems of the critical members, because they are small, light, cheap, and useful as a $built-in$ actuator/sensor system, and show a small power-requirement. At first, research backgrounds and motivations for current studies are described, and previous research works related to the topics of active sensing-based SHM techniques using the piezoelectric sensors are discussed. Wireless SHM systems are also reviewed briefly. Active sensing-based SHM systems composed of several piezoelectric active sensors are presented in conjunction with both electro-mechanical impedance-based method and guided waves-based method to detect incipient damage which may occur on the critical members. The active sensing-based SHM systems are developed using statistical pattern recognition algorithms such as support vector machine (SVM) and outlier analysis (OA) to identify the location, severity, and type of damage on the critical members. The pattern recognition algorithms analyze statistical distributions of the damage sensitive features (such as root-mean-square-deviation (RMSD) for the impedance signatures and wavelet coefficients (WC) for maximum energy mode of the guided waves) derived from the measured data to enhance damage detection and classification processes. The feasibility of the proposed SHM strategies is investigated through a series of example studies using a steel bridge member, an aluminum plate, and a rail specimen. With a current trend of SHM heading towards unobtrusiv...