Local Damage Detection In Continuous Steel-Concrete Composite Beam Based On Electro-Mechanical Impedance (EMI)

In several engineering applications,it is desirable to know the behavior of structures under loading conditions.One reason is to help optimize the design and prevent anomalies,deterioration and local damages which might occur during service and operation.The local damage represents a serious problem which can cause catastrophic failure and operational incidents of structures.Therefore,Structural Health Monitoring(SHM)has received considerable attention in recent years.Nevertheless,due to the characteristics of multiphase and inhomogeneity of civil engineering structures,traditional inspection methods such as: visual inspection,eddy current and ultrasonic technique become very tedious,expensive and even unreliable.In recent years,the development of Structural Health Monitoring(SHM)based on smart materials such as piezoceramics have emerged as new tool due to their advantages of active sensing,low cost,quick response,availability in different shapes,and simplicity for implementation.This study concentrated on the Electro-Mechanical Impedance(EMI)technique based on piezoelectric(PZT)patch.The main merits of EMI technique for damage detection are its high frequency actuation feature and non-model based,so it can detect the occurrence of structural damage and is sensitive to small local damage.With that in mind,the aim of this research is to develop a novel technique to detect the local damage in continuous steel-concrete composite beam with two symmetric points loads based on the Electro-Mechanical Impedance(EMI).Therefore,a new idea to bond the PZT patch on the shear stud of steel-concrete composite beam is proposed to analyze the influence of damage distance s or/and damage depth d to the PZT patch based on the real part of PZT admittance.In particular,the numerical simulation of steel-concrete composite beam under load condition using ANSYS software was performed to understand the basic behavior and to evaluate the presence of damages.Based on this result,the piezoelectric-beam for harmonic analysis were then carried out in a frequency range of 20 to 30 kHz using the same finite element approach.Furthermore,the local damage was quantified in non-parametric terms using the root mean square of the deviation(RMSD).The numerical results show that the proposed methods of EMI based on PZT patch bonded on the shear stud are effective in identifying the existence and detection of local cracks damages in steel-concrete composite beam.Thus,the stiffness of concrete slab,the resistance of shear stud and the stiffness of steel beam decrease with the increase of damage.The detecting ability of the PZT patch to the crack damage in concrete slab,between the concrete and shear stud and between the steel beam and concrete slab increases with decreasing the distance between the PZT patch and crack damage.In addition,the root mean square deviation(RMSD)index was found to correlate well with the damage progression in the steel-concrete composite beam.The results of this numerical simulation will be helpful for further research in Structural Health Monitoring(SHM).Thus,an experimental study of the same topic can be performed to verify the validity of the Electro-Mechanical Impedance(EMI)technique.Challenging task like incorporation of a new size and shape of PZT patch(apart from rectangular)in steel-concrete composite beam is another critical aspect to be studied in the further.