Influence of Axial Load on Electromechanical Impedance (EMI) of Embedded Piezoceramic Transducers in Steel Fiber Concrete

Abstract

With the advantages of high tensile, bending, and shear strength, steel fiber concrete structures have been widely used in civil engineering. The health monitoring of concrete structures, including steel fiber concrete structures, receives increasing attention, and the Electromechanical Impedance (EMI)-based method is commonly used. Structures are often subject to changing axial load and ignoring the effect of axial forces may introduce error to Structural Health Monitoring (SHM), including the EMI-based method. However, many of the concrete structure monitoring algorithms do not consider the effects of axial loading. To investigate the influence of axial load on the EMI of a steel fiber concrete structure, concrete specimens with different steel fiber content (0, 30, 60, 90, 120) (kg/m3) were casted and the Lead Zirconate Titanate (PZT)-based Smart Aggregate (SA) was used as the EMI sensor. During tests, the step-by-step loading procedure was applied on different steel fiber content specimens, and the electromechanical impedance values were measured. The Normalized root-mean-square deviation Index (NI) was developed to analyze the EMI information and evaluate the test results. The results show that the normalized root-mean-square deviation index increases with the increase of the axial load, which clearly demonstrates the influence of axial load on the EMI values for steel fiber concrete and this influence should be considered during a monitoring or damage detection procedure if the axial load changes. In addition, testing results clearly reveal that the steel fiber content, often at low mass and volume percentage, has no obvious influence on the PZT’s EMI values. Furthermore, experiments to test the repeatability of the proposed method were conducted. The repeating test results show that the EMI-based indices are repeatable and there is a great linearity between the NI and the applied loading.

Electro-Mechanical Impedance (EMI) Based Interlayer Slide Detection Using Piezoceramic Smart Aggregates—A Feasibility Study

“…The embedded PZT patch has a diameter of 10 mm and a height of 0.3 mm. The smart aggregate has been widely used in structural health monitoring of various structures with active sensing approach [ 40 , 41 , 42 ], EMI technique [ 43 ] and acoustic emission method [ 44 ]. Previous researches have verified that the SA-based methods are feasible and effective approaches in structural health monitoring field.…”

Debonding Detection of Reinforced Concrete (RC) Beam with Near-Surface Mounted (NSM) Pre-stressed Carbon Fiber Reinforced Polymer (CFRP) Plates Using Embedded Piezoceramic Smart Aggregates (SAs)

“…Therefore, many scholars have conducted extensive research on the health monitoring of CFRP-reinforced structures based on piezoceramic transducers. Furthermore, piezoceramic materials can also enable electromechanical impedance (EMI) technology [24] and the smart aggregates (SAs) based active sensing method in SHM [25]. By comparing the changes of electrical impedance signals before and after structural damage, EMI technology can be used to diagnose the structural damage due to the electromechanical coupling characteristics of piezoceramics [26].…”

Design, Analysis, and Experiment on a Novel Stick-Slip Piezoelectric Actuator with a Lever Mechanism

“…Though the piezoelectric effect was discovered more than a century ago, research on piezoelectric is still ongoing [1][2][3][4][5] and attracts attention in many areas [6][7][8][9][10]. One of the areas is actuation.…”