Acoustic Emission Monitoring And Evaluation Of Damage In Prestressed Prefabricated Rocking Shear Walls Under Reciprocating Load

RC shear walls are the primary lateral-load-resisting system for high-rise buildings,and prefabricated shear wall has been concerned and studied by growing scholars.With the rapid development of prefabricated structure in China,the Structural health monitoring of prefabricated shear wall structure need to be developed.Prestressed fabricated rocking shear wall is a new type of fabricated shear wall,which has good seismic energy dissipation and self reset ability.Its damage mechanism in the process under reciprocating loading needs more research.Acoustic emission monitoring technology is a real-time nondestructive testing method,which analyze the damage by stress wave from the structure.In this paper,AE technique was applied to monitor and evaluate the Board-Connected Prestressed Rocking Wall and the Grouted Sleeve-Connected Prestressed Rocking Wall.The primary research contents and results are introduced as follows:Firstly,acoustic emission technology is used to monitor the process of the reciprocating loading of the Prestressed Prefabricated Rocking Shear Walls.Based on the the AE singals and experimental phenomena,and the damage evolution process of Prestressed Prefabricated Rocking Shear Walls under reciprocating loading are divided into three stages.The cumulative energy of acoustic emission are used to evaluate the mechanical properties of shear wall members,such as strain,residual displacement and stiffness degradation.Then,the correlation between acoustic emission characteristic parameters is studied;RA and AF parameters are used to analyze the crack damage types,the damage mechanism of prestressed fabricated rocking shear wall with two connection modes is studied and the Gaussian mixture modelling is employed to classify the tensite and shear cracks obtained from the AE experiments;b-value curve is studied,combined with the loading conditions,which could show obvious regular change trend that reflect different failure modes of the Prestressed Prefabricated Rocking Shear Walls in the different loading condition;The intensity signal analysis（ISA）and the cyclic loading parameter ratio are applied to analyze the damage process from initial to failure stage.Finally,the damage pattern recognition analysis of Prestressed Prefabricated Rocking Shear Walls is studied based on the characteristic parameters of acoustic emission.Principal component analysis（PCA）and clustering method were used to cluster the characteristic parameters rise time,ring count,energy,average frequency,peak frequency and RMS into five clusters reflecting the information of different damage events.Based on the characteristics of different AE event sources and the loading phenomenon of shear wall,the clustering results are connected with the actual damage,and the damage components contained in the clustering results are analyzed.