Simulation Study On Mechanism Of Interface Debonding Defects Detection In Concrete-filled Steel Tubular Using Surface Wave With Piezoelectric Ceramics

Concrete-filled steel tubular(CFST)structures are often used as vertical load-bearing components in high-rise buildings and in long-span bridges because of their superior mechanical properties.However,due to the uneven hydration heat during the pouring process,shrinkage and creep of concrete core,poor construction management,etc.,the interface debonding between concrete core and steel tubular occurs possibly.The debonding weakens the confinement effect of steel tubular on concrete core and leads to decrease in load-carrying capacity of CFST members.Therefore,it is of great significance to develop efficient interface debonding detection approaches for CFST members.In this paper,the mechanism of interface debonding detection approach using surface wave measurement with PZT actuator and sensor is investigated numerically.The findings from the numerical simulation meet the test observations.The work of this thesis mainly includes the following contents:(1)The recent development and application of Piezoelectric materials based structural damage detection for civil engineering structures have been introduced with an emphasis on the interface debonding and concrete defect detection for concrete-filled steel tubular(CFST)and other concrete-steel composite structures.(2)An interface debonding detection approach using surface wave measurement from PZT materials for CSFT member is proposed and the excitation signal selection and the processing by a suitable window function are discussed.(3)Considering the piezoelectric effect and the electromechanical coupling effect between piezoelectric ceramics and CFST,a PZT-CFST coupling model is established with ANSYS to simulate the surface wave propagation in CFST for the purpose of understanding the effect of interface debonding on the surface wave propagation.(4)The findings from the numerical study on the effect of interface debonding defect on the propagation of surface wave of CFST is compared with the test results.Results show that the findings from the simulation agree with the test observation and the numerical simulation results show the interface debonding detection approach using surface wave measurement is efficient for CFST structures...