MASW Method-based Interfacial Damage Detection For Steel-concrete Composite Structures

With the development of civil engineering industry,the steel-concrete composite structures have been widely applied in complex civil infrastructures due to their excellent mechanical properties.However,the interfacial damage of steel-concrete composite structure is an important factor affecting the performance of composite structure.It is urgent to develop the nondestructive testing(NDT)method for the interfacial damage detection of steel-concrete composite structures to guarantee the mechanical performance and structural safety of civil structures.In this paper,the multi-channel surface wave analysis(MASW)based steel-concrete composite structure interfacial damage detection technology is proposed to avoid the technical shortcomings of conventional NDT techniques.In this study,the theoretical analysis on the dispe rsion characteristics of surface waves in steel-concrete composite structures was carried out in-depth.The high-frequency data acquisition system for MASW experiment was developed.Meanwhile,experimental validation on the efficiency of MASW-based NDT testing on steel-concrete composite structures was performed.The research results can provide important guiding significance to the actual application of interface damage detection for steel-concrete composite structures.(1)In the aspect of theoretical analysis,the detection mechanism of MASW method was discussed on the basis of theoretical models of bonding and debonding areas in steel-concrete composite structures established in this study.The results show that an obvious platform section can be observe d in the dispersion curve corresponding to bonding area.However,the wave velocity of debonding area decreases continuously in low-frequency regions.The surface wave velocity in the bonding area is greater than that of debonding area.(2)For the purpose of achieving experimental study,a multi-channel highfrequency data acquisition system for damage detection experiment s was developed.Meanwhile,the supporting software for data acquisition and analysis was compiled and developed.Then,the experimental research on the optimal selection of sensors was carried out.The results show that piezoelectric ceramic,acceleration sensor,ultrasonic transducers and scanning laser vibration meter can realize effective data acquisition for MASW measurement.Besides,the PZT ceramic patch and force hammer can be used as the excitation source of surface waves.(3)In the aspect of experimental validation of MASW methodology,three groups of concrete-filled steel tube components with different defect lengths,defect depths,and steel plate thicknesses were designed.The results show that the MASW-based NDT testing system developed in this study can effectively detect the debonding defects in steel-concrete composite structure.(4)Based on the experimental measurement,the parametric analysis was performed at the end of this study.The influence of defect proportion,array spacing,and array length on the detection accuracy of MASW was investigated.The results indicate that the defect proportion directly affects the var iation trend of the dispersion curve,and the array length mainly affects the detection resolution and the lower limit of the detection frequency band.When the array length is large,the influence of minor defects on the dispersion characteristics of surface waves is not significant.The low-frequency characteristics of the surface wave cannot be recognized while the array length is insufficient.Besides,the error suppression ability of MASW method decreases significantly in the experimental test without enough transducers.In this study,the systematic theoretical analysis,experimental research,and parameter analysis were carried out to experimentally validate the feasibility of MASW-based interface damage method for steel-concrete composite structures.In the end,a complete guideline for the MASW experiment was proposed.The research findings of this study can further improve the nondestructive testing technology of steel-concrete composite structures and can be used to guide the practical engineering application of MASW method.