A near and far-field monitoring technique for damage detection in concrete structures

Providakis, Costas,Stefanaki, K.,Voutetaki, M.,Tsompanakis, J.,Stavroulaki, M. Techno-Press 2014 Structural monitoring and maintenance Vol.1 No.2

Real-time near and far-field monitoring of concrete structural components gives enough information on the time and condition at which damage occurs, thereby facilitating damage detection while in the same time evaluate the cause of the damage. This paper experimentally investigates an integrated monitoring technique for near and far-field damage detection in concrete structures based on simultaneous use of electromechanical admittance technique in combination with guided wave propagation. The proposed sensing system does not measure the electromechanical admittance itself but detect time variations in output voltages of the response signal obtained across the electrodes of piezoelectric transducers bonded on surfaces of concrete structures. The damage identification is based on the spectral estimation MUSIC algorithm. Experimental results show the efficiency and performance of the proposed measuring technique.

Detection of flexural damage stages for RC beams using Piezoelectric sensors (PZT)

Karayannis, Chris G.,Voutetaki, Maristella E.,Chalioris, Constantin E.,Providakis, Costas P.,Angeli, Georgia M. Techno-Press 2015 Smart Structures and Systems, An International Jou Vol.15 No.4

Structural health monitoring along with damage detection and assessment of its severity level in non-accessible reinforced concrete members using piezoelectric materials becomes essential since engineers often face the problem of detecting hidden damage. In this study, the potential of the detection of flexural damage state in the lower part of the mid-span area of a simply supported reinforced concrete beam using piezoelectric sensors is analytically investigated. Two common severity levels of flexural damage are examined: (i) cracking of concrete that extends from the external lower fiber of concrete up to the steel reinforcement and (ii) yielding of reinforcing bars that occurs for higher levels of bending moment and after the flexural cracking. The purpose of this investigation is to apply finite element modeling using admittance based signature data to analyze its accuracy and to check the potential use of this technique to monitor structural damage in real-time. It has been indicated that damage detection capability greatly depends on the frequency selection rather than on the level of the harmonic excitation loading. This way, the excitation loading sequence can have a level low enough that the technique may be considered as applicable and effective for real structures. Further, it is concluded that the closest applied piezoelectric sensor to the flexural damage demonstrates higher overall sensitivity to structural damage in the entire frequency band for both damage states with respect to the other used sensors. However, the observed sensitivity of the other sensors becomes comparatively high in the peak values of the root mean square deviation index.

A new damage identification approach based on impedance-type measurements and 2D error statistics

Providakis, Costas,Tsistrakis, Stavros,Voutetaki, Maristella,Tsompanakis, Yiannis,Stavroulaki, Maria,Agadakos, John,Kampianakis, Eleftherios,Pentes, George Techno-Press 2015 Structural monitoring and maintenance Vol.2 No.4

The electro-mechanical impedance (EMI) technique makes use of surface-bonded lead zirconate titanate (PZT) patches as impedance transducers measuring impedance variations monitored on host structural components. The present experimental work further evaluate an alternative to the conventional EMI technique which performs measurements of the variations in the output voltage of PZT transducers rather than computing electromechanical impedance (or admittance) itself. This paper further evaluates a variant of the EMI approach presented in a previous work of the present authors, suitable, for low-cost concrete structures monitoring applications making use of a credit card-sized Raspberry Pi single board computer as core hardware unit. This monitoring approach is also deployed by introducing a new damage identification index based on the ratio between the area of the 2-D error ellipse of specific probability of EMI-based measurements containment over that of the 2-D error circle of equivalent probability. Experimental results of damages occurring in concrete cubic and beam specimens are investigated under increasing loading conditions. Results illustrate that the proposed technique is an efficient approach for identification and early detection of damage in concrete structures.

Detection of flexural damage stages for RC beams using Piezoelectric sensors (PZT)

Chris G. Karayannis,Maristella E. Voutetaki,Constantin E. Chalioris,Costas P. Providakis,Georgia M. Angeli 국제구조공학회 2015 Smart Structures and Systems, An International Jou Vol.15 No.4

Structural health monitoring along with damage detection and assessment of its severity level innon-accessible reinforced concrete members using piezoelectric materials becomes essential since engineersoften face the problem of detecting hidden damage. In this study, the potential of the detection of flexuraldamage state in the lower part of the mid-span area of a simply supported reinforced concrete beam usingpiezoelectric sensors is analytically investigated. Two common severity levels of flexural damage areexamined: (i) cracking of concrete that extends from the external lower fiber of concrete up to the steelreinforcement and (ii) yielding of reinforcing bars that occurs for higher levels of bending moment and afterthe flexural cracking. The purpose of this investigation is to apply finite element modeling using admittancebased signature data to analyze its accuracy and to check the potential use of this technique to monitorstructural damage in real-time. It has been indicated that damage detection capability greatly depends on thefrequency selection rather than on the level of the harmonic excitation loading. This way, the excitationloading sequence can have a level low enough that the technique may be considered as applicable andeffective for real structures. Further, it is concluded that the closest applied piezoelectric sensor to theflexural damage demonstrates higher overall sensitivity to structural damage in the entire frequency band forboth damage states with respect to the other used sensors. However, the observed sensitivity of the othersensors becomes comparatively high in the peak values of the root mean square deviation index.

Comparisons of smart damping treatments based on FEM modeling of electromechanical impedance

Providakis, C.P.,Kontoni, D.P.N.,Voutetaki, M.E.,Stavroulaki, M.E. Techno-Press 2008 Smart Structures and Systems, An International Jou Vol.4 No.1

In this paper the authors address the problem of comparing two different smart damping techniques using the numerical modelling of the electro-mechanical impedance for plate structures partially treated with active constrained layer damping treatments. The paper summarizes the modelling procedures including a finite element formulation capable of accounting for the observed behaviour. The example used is a smart cantilever plate structure containing a viscoelastic material (VEM) layer sandwiched between a piezoelectric constrained layer and the host vibrating plate. Comparisons are made between active constrained layer and active damping only and based on the resonance frequency amplitudes of the electrical admittance numerically evaluated at the surface of the piezoelectric model of the vibrating structure.

Comparisons of smart damping treatments based on FEM modeling of electromechanical impedance

C. P. Providakis,D.-P. N. Kontoni,M. E. Voutetaki,M. E. Stavroulaki 국제구조공학회 2008 Smart Structures and Systems, An International Jou Vol.4 No.1

In this paper the authors address the problem of comparing two different smart damping techniques using the numerical modelling of the electro-mechanical impedance for plate structures partially treated with active constrained layer damping treatments. The paper summarizes the modelling procedures including a finite element formulation capable of accounting for the observed behaviour. The example used is a smart cantilever plate structure containing a viscoelastic material (VEM) layer sandwiched between a piezoelectric constrained layer and the host vibrating plate. Comparisons are made between active constrained layer and active damping only and based on the resonance frequency amplitudes of the electrical admittance numerically evaluated at the surface of the piezoelectric model of the vibrating structure.