Research On Interface Damage Indentification Of Concrete Filled Steel Tubular Members Using Piezoelectric Guided Waves

In recent years,concrete-filled steel tubular structures(CFSTs)have been widely used in civil engineering.The load carrying capacities of members in CFSTs have been improved by casting concrete into steel pipes,facilitating construction and reducing the cost.The CFSTs have been playing a vital role in the development of the world's buildings and industry infrastructures.However,due to improper construction management and defects in steel pipes and concrete material,CFSTs often have defects such as cracks,voids and peeling,etc.,resulting in a decline in the performance of the entire building structure.When the structure cannot meet the requirement of the bearing capacity,it will bring great safety threats to people's lives.This will not only bring huge property losses,but also cause casualties.Therefore,it is essential to carry out structure health monitoring(SHM)for CFST structures.Piezoelectric ceramic such as Lead Zirconite Titanite(PZT)is one of typical smart materials,which has properties of light weight,low cost and high sensitivity,easy to adhere to the surface of the structure,etc.In addition,piezoceramics can be used as both actuators and sensors in SHMs,improving the working efficiency.Nowadays,PZT-based ultrasonic guided wave(UGW)technology has been widely applying in SHMs.In this paper,a combination of theoretical analysis,finite element analysis(FEA)and experimental verification are respectively used to verify and analyze the peeling damage of CFST structures based on piezoceramic UGWs,including two parts of numerical simulation and experimental validation.Firstly,the theoretical study on the propagation characteristics of UGWs at the CFST interface is carried out.Since the guided wave has frequency dispersion characteristics and multi-modality,it will be superimposed during the propagation process which will make a difficulty to the signal processing.Therefore,according to the theoretical frequency dispersion curves,the selection of the appropriate excitation frequency plays a crucial role in the test results.Secondly,the finite element software ABAQUS is used to simulate the health components and the CFST components with an interfacial damage.In order to explore the feasibility of numerical simulation for damage degree and damage location identification,the signal amplitude change and the signal travel time can be analyzed from the extracted signal by changing the size and position of the peeling damage.Then,the damage identification experiments of CFST members using PZT-based UGWs are performed.A 5-cycle sinusoidal superimposed signal modulated by Hanning window is selected as the excitation signal.A test operation system is established to actuate the testing signals by a PZT array located at the excitation end,and collect and process the testing signals by another PZT array at the receiving end.In this study,two methods are used to identify and locate structural peeling damage,which are the signal energy method and time reversal method,respectively.The feasibility of the two methods is analyzed and the applicability of different methods is compared.Finally,the main conclusions,the innovation abstract and future work are discussed.