| Carbon fiber reinforced polymer(CFRP)has been widely used in the field of strengthening and reconstruction of reinforced concrete structures because of its high strength and light weight.Due to the existence of early internal defects of strengthened reinforced concrete structures and the debonding between externally bonded CFRP(EBCFRP)and reinforced concrete after the mentioned strengthening technique,the overall mechanical properties of reinforced components will be significantly weakened.Thus,it is of great significance to assess the damage status of CFRP reinforced concrete components.In this thesis,the numerical simulation research on the stress wave propagation detection technique of EB-CFRP strengthened concrete components with defects is carried out based on the application of externally mounted PZT patches.Accordingly,a reasonable damage index is defined.The main contents of the research are as follows:1.The Wave Propagation detection method was implemented,the PZT patches were externally mounted in the ipsilateral method to detect the debonding defects between CFRP and the concrete component.For the concrete core void defect,the PZT patches were externally mounted in the contralateral method.The choice for varying PZT patches mounting method for detection was decide due to the analyzed internal defect in order to improve the accuracy of the results.2.The difference of stress wave field in two-dimensional reinforced components with different types and sizes of defects under point load was analyzed,and the influence of defects in reinforced components on stress wave field was demonstrated.3.Considering the direct and inverse piezoelectric effects of PZT materials due to their electromechanical coupling effects with the capability to behave as an actuator or sensor for the monitored reinforced component,a two-dimensional Multiphysics field coupling finite element model is established.Attenuation of the response signal due to different defects after the excitation of voltage signals(sinusoidal signal and sweep frequency signal)through the monitored reinforced component were studied numerically.The corresponding evaluation indexes are proposed to quantitatively describe the severity of defects. |
