Experimental Study On Interface Debonding Detection For A Rectangular Concrete-filled Steel Tubular Using Surface Wave Measurement From PZT Patches

Concrete-filled steel tubulars(CFSTs)structures have been widely utilized in large span bridges and super high-rise building structures as typical vertical or axial force component due to its advanced mechanical performance by taking advantages of the advance materials properity of concrete and steel materials and the confinement effect of steel tubular on concrete core.However,During in the construction of CFSTs,the interface debonding between steel tubular and the confined concrete core leads to negative effects on the mechanical properties including load-carrying capacity of CFST and safety risk as a result of non-uniform temperature field,and the effect of creep and shrinkage of concrete.Therefore,it is of great significance to develop non-destructive interface debonding detection approaches for CFSTs structures.Compared with traditional non-destructive testing(NDT)methods,piezoelectric lead zirconate titanate(PZT)materials based damage detection approaches for CFST members have received a great deal of attentions in recent years due to the advantages of PZT materials such as actuating and sensing functions,fast response,high sensitivity,and wide frequency response range.Because of the unassessability of interface debonding defects of CFSTs,the non-destructive interface debonding detection of CFSTs is still a challenging task.Based on previous studies,an interface debonding defect detection approach using surface stress wave measurement actuated and measured with PZT actuators and sensors attached on the same side of the CFST members has been proposed..A set of CFSTs members with interface debonding defects are designed and experimental study on the interface debonsing detection using surface wave measurement is carried out and the performance of the propoised approach is valiadated.The related work of this article is as follows:(1)After reviewing the development of PZT based defect detection for CFST in recent years,the principle of the interface debonding detection approach for CFST members using surface wave measurement with surface-mounted PZT patches and embedded PZT SA as actuation and sensers is introduced.Moreover,the embedded piezoelectric SAs are normalized to reduce the dispersion of test data.(2)A set of scale CFSTs members with different interface debonding defects are designed and surface-mounted PZT actuators and sensors and embedded piezoelectric SAs are employed to detect interface debonding defects.In the interface debonding defect detection approachproposed in this paper,the PZT actuators and sensors are attached on the same side of the CFST specimens.Based on frequency domain analysis on the surface-mounted PZT measurement under simple harmonic sinusoidal signals and pulse signals excitations,the interface damage index and the standard interface damage index are defined.The test results show the feasibility and effectiveness of the proposed interface debonding detection for CFSTs structure based on PZT surface wave measurement.(3)After validating the feasibility of the proposed interface debonding defects detection approach using surface wave measurement,the proposed approach is employed to detect the interface conition of large-scale CFST members of a super high-rise building.The defined damage indices are employed to evaluate the interface condition and the results show that damage indices of the tested outer frame CFST columns are within a reasonable range.The interface between the inner concrete core and the steel tubular of the outer frame CFST column is in good condition.