Damage and retrofitting monitoring in reinforced concrete structures along with long-term strength and fatigue monitoring using embedded Lead Zirconate Titanate patches

Abstract

This article aims at developing a generic system for the damage and retrofitting monitoring along with long-term strength and first-stage fatigue monitoring of reinforced concrete structures using embedded Lead Zirconate Titanate sensors in the form of concrete vibration sensors. The concrete vibration sensor is a ready-to-use sensor, and its unique packaging renders it very compatible for embedment in reinforced concrete structures. In addition to cost-effectiveness, the concrete vibration sensors are also characterized by excellent structure-compatibility and durability. In this article, both finite element method and experimental investigations have been employed to establish the feasibility of using curvature (second-order derivative) and other higher order derivatives of displacement mode shapes for damage detection and retrofitting assessment. The experiments are conducted on a real-life-sized reinforced concrete beam. The concrete vibration sensors embedded on the outer faces of the reinforced concrete beam are coupled to obtain the curvature and higher order mode shapes of the beam in pristine, damaged and retrofitted conditions. It is found that the curvature mode shape–based response of concrete vibration sensors can successfully identify the location of damage both numerically and experimentally. However, the third-order mode shape is unable to correctly identify the location of damage. Before introducing damage in the beam, the effect of long-term dynamic loading from Day 6 to Day 108 after casting of the reinforced concrete beam is also monitored. Both the global monitoring technique (in which flexural rigidity of the beam is monitored) and the local electro-mechanical impedance technique (where the equivalent stiffness identified by concrete vibration sensors is monitored) successfully detected the decreasing fatigue strength of the reinforced concrete beam. Degradation of the strength of reinforced concrete beam results due to the development of micro-cracks in the concrete because of the continuous vibrations (9.3 million load cycles) experienced by it via shaker. This is the first-of-its-kind proof-of-concept application of equivalent stiffness concept for monitoring curing of a large-sized reinforced concrete structure. It is also the first study on first-stage fatigue monitoring carried out before the ‘retrofitting-stage’ of the structure. Complete experimental investigations after the ‘retrofitting-stage’ covering all three stages of fatigue have been covered by the authors in their related publication.

Strength development monitoring and dynamic modulus assessment of cementitious materials using EMI-Miniature Prism based technique

“…The piezoelectric material–based techniques, namely the wave propagation (WP) technique 1–4 and the electromechanical impedance (EMI), 5–11 have been developed in the last two decades serving as an alternative to the traditional NDT techniques for structural assessment. 12,13 In the EMI technique, the low-profile transducers, lead zirconate titanate (PZT) patches, are permanently mounted on the host structure for active measurement of the system’s EMI.…”

Early Age Concrete Strength Monitoring Using Power Spectral Density and Wavelet Packet Analysis

“…Lead zirconate titanate (PZT), as one of the most widely used intelligent materials at present, can generate an electric charge when subjected to a stress or strain and can likewise generate a stress or a strain when subjected to an electric field. Due to its fast response, wide frequency response range, easy tailoring, and low price, it has great application potential in structural health monitoring [43][44][45][46]. In order to protect a fragile PZT patch, the first 2…”

A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers

“…The reason being the less importance of energy efficiency and other less stringent requirements of signal waveform, space and criticality of application. The devices for applications like biomedical imaging [6][7][8], acoustic emission [9,10], condition monitoring [11,12], nondestructive evaluation (NDE) [13][14][15][16][17], and structural health monitoring (SHM) [18][19][20][21][22] are to be designed considering the performance as a whole system due to the criticality of the tasks they perform like damage or defect detection. The system here includes the sensors or actuators, driving electronics and the target object.…”