Research On Interface Peeling Damage Identification Of Steel-Concrete Composite Slabs Based On MASW

In steel-concrete composite structural slabs,the composite interface peeling damage will significantly reduce the composite effect and seriously affect its safety.It is of great significance to effectively identify the interface peeling damage existing in composite slabs.However,in steel-concrete composite slabs,the peeling damage is localized and concealed and belongs to interface damage,which brings great challenges to the identification of peeling damage.In this paper,theoretical analysis,numerical simulation and experimental research are combined to research,in order to propose a method of interface peeling damage identification of steelconcrete composite slabs based on multi-channel surface wave analysis(MASW).The method has the characteristics of convenience,rapidness,sensitivity to interface damage and high identification accuracy.The main contents of this paper include the following aspects :(1)According to the solid elastic wave equation,the Rayleigh wave equation is deduced,and the basic law of Rayleigh wave propagation in semi-infinite space is summarized.Then,the finite element analysis software ABAQUS is used to establish a nearly semi-infinite pure concrete medium model.The dynamic analysis method based on explicit central difference is adopted to study different components of elastic waves in the medium,extract the dispersion curve of Rayleigh wave,and verify the basic law of propagation of Rayleigh wave.(2)The finite element model of steel-concrete composite slab is created,and the method of deleting some concrete elements is adopted to simulate the interface peeling damage.The MASW damage identification algorithm based on wave velocity attenuation is established,and the interface peeling damage identification is carried out according to the wave velocity attenuation law of surface waves.(3)A test platform for interface peeling damage of MASW steel-concrete composite slabs is built,and a six-channel MASW damage identification test is conducted to verify the effectiveness of the proposed interface peeling damage identification algorithm.Combined with the calculation results of the three-dimensional composite slab model,a comparative analysis is conducted to establish the damage index and improve the damage identification algorithm.The results show that :(1)Based on the two-dimensional plane wave theory,the interface peeling damage of composite plates causes the phenomenon of "shunting" of surface waves and the attenuation of wave velocity,and the attenuation amplitude of wave velocity is approximately linear and positively correlated with the peeling length.(2)When the surface wave propagates in the healthy area of the composite plate specimen,the wave velocity between each channel basically remains unchanged.However,in the damaged area,the wave velocity of the surface wave attenuates to a large extent.It can be clearly seen that the initial channel of the wave velocity attenuation just corresponds to the starting point and end point of the peel damage.(3)The proposed MASW based interface peel damage identification algorithm of steel-concrete composite slab is effective,and the identification accuracy reaches centimeter level.