Research On The Acoustic Emission Characteristics Of The Bond Interface Between Prestressed Reinforcement And Concrete

Bonding function between reinforced and concrete is one of complex interactions, which can transfer stress and coincident deformation between reinforced and concrete, and it is the base of two can work together.Because the study on the properties of the interface between reinforced and concrete is one of important parts to reveal entire work performance of reinforced concrete structure,so the problem of interface bonding has great value to research.At present,many results of research on the interface bonding problem have been gained,but research techniques used were still very single,the main reason is that only general mechanics testing was uesed,not applied Acoustic Emission(AE) technology,therefore,an application of AE technology is developed to solve the bond problem of interface in this paper.AE technology has many testing features,such as real-time,dynamic,simple and non-destructive detection,etc.,so it has great potential in structural engineering,but the theoretical foundation of AE compared with itself technological level is still lagging,a large number of results derived from laboratory and field tests were lack of theoretical analysis,and lack of mechanical methods to effective study the relationship of AE regular pattern and macroscopic mechanical parameters of bonding interface damage,so,the relationship of the bond-slip law and AE distribution can not set up.Therefore,the key of the research is to clarify the relationship of AE signal and mechanical course of bonding interface damage,and the AE mechanisms,only in this way,AE can be used as an important detecting technology for fracture process.Firstly,the characteristic function is given for description of AE activity,the relationship between AE parameters and damage variables,the equation of damage evolution and the constitutive equations presented by AE parameters are derived.The rightness of the evolution equation has been verified through exmple.Secondly,two different types of pull-out specimen were designed,the one are cube specimens made of spiral qrooves and round steel bars which embedded in the core of concrete respectively,and the other are rectangular parallelepiped made of spiral qrooves pre-pulled with prestress which embedded in the core of concrete,then,the two pull-out specimens were tested by AE technology.In the tests,the AE signal acquisition system records the AE signals in the process of the specimen was pulled out.Through the curve of load-slip,the process are divided into several different stages,and then AE parameters analysis and spectral analysis and Gabor wavelet analysis are carded out to analyse AE signals above load stages,in the end the AE characteristics of bonding interface between prestressed reinforcement and concete are gained.