Research On Damage Characteristics Of High Strength Concrete Specimen Based On Acoustic Emission Technology

Concrete is the most widely used and most used building material in civil engineering.High-strength concrete has many advantages such as ultra-high strength and toughness,good durability,and a relatively stable shape for a long period of time.It is in a large-scale civil engineering framework.There is a very wide range of effects expected in memory.And because it is a heterogeneous multiphase composite material,the randomness of the initial shortcomings inherent in this type of material affects its mechanical properties,which will show very obvious nonlinearity during the related use process.The damage effect of the concrete caused by the original shortcomings of it will cause the damage to appear very significant dynamic change.And in order to be able to study and explain the complete process of damage evolution of high-strength concrete materials more in-depth,so as to achieve the ability to predict the damage and destruction of concrete structures in advance,this topic will be based on concrete components in real-life engineering applications.The uniaxial compression and flexural cyclic loading and unloading experiments,through the skilled use of relevant acoustic emission technology,have completed the discussion on the damage characteristics of concrete with a relatively high level of strength.Based on the damage theory,a constitutive model of concrete damage is established.The main work of this paper is as follows:(1)Determine the setting parameters of the acoustic emission acquisition system through experiments,set the system threshold,system gain and timing parameters,design and determine the arrangement of acoustic emission sensors,and set up the load signal and damage signal synchronization to study the evolution characteristics of concrete damage experiment platform.(2)Prepare high-strength concrete specimens with strength grades of C60,C70,and C80 respectively,and perform cyclic loading and unloading compression experiments on them,and analyze the damage characteristics of high-strength concrete materials under compression using a multi-parameter acoustic emission system.Based on the relationship curve between acoustic emission characteristic signal and arrival time,the damage characteristics of concrete materials at different loading stages are obtained.According to the acoustic emission energy count,the cyclic loading and unloading process of high-strength concrete is divided into three stages: the initial loading stage,the crack development stage and the instability failure stage.The relationship between the number of events and the load is used to verify the high-strength concrete under loading and unloading.The effectiveness of Kaiser effect and Felicity effect.(3)Using the high-strength concrete beam flexural test,based on the full collection of acoustic emission ringing count,energy and other characteristic parameters,multi-parameter analysis of the damage characteristics of the high-strength concrete beam under the flexural test.Combining the characteristics of the damage evolution described by each parameter can be used to analyze the damage evolution of high-strength concrete beams in the bending deformation state.(4)In this paper,through the damage evolution characteristics test of high-strength concrete specimens,based on the variable of defect area,the number of acoustic emission events is used to define the damage variables of the axial compression test of high-strength concrete specimens.Based on the number of acoustic emission events,the axial compression test damage evolution equation of high-strength concrete specimens is obtained.In this way,the evolution of the damage of high-strength concrete can be effectively linked to the superiority of the macro-mechanical properties.