| The reasons for the durability deterioration of reinforced concrete structures can be divided into two categories.One is the corrosion deterioration of concrete materials.The other is corrosion of steel reinforcement in concrete.It is necessary and urgent to study the damage and deterioration process of reinforced concrete under the combined action of load and chloride environment.Acoustic emission technology is widely used in the field of composite materials due to its advantages such as dynamic monitoring of the failure characteristics of composite materials.This paper takes reinforced concrete member as the research object,centering on the damage identification and deterioration evaluation of corroded reinforced concrete beam and column under the joint action of load and chloride salt environment,the following research work is carried out.(1)In order to study the deterioration rule of load-damaged concrete based on acoustic emission technology,three kinds of uniaxial compression acoustic ermission tests of C35 concrete test blocks were conducted.Through the experience analysis,distribution analysis and correlation analysis of signal parameters,the damage and deterioration law of concrete in time change are studied,and the damage threshold is related to the age and proportion of concrete.In this paper,the criterion for the decompression and deterioration of concrete under uniaxial compression based on acoustic emission and the corresponding relation between different acoustic emission sources and acoustic emission signals are proposed.(2)In order to study the mutation state in the process of damage evolution of concrete,the three-point bending acoustic emission test of preset cracked concrete beam was conducted.According to the characteristics of acoustic emission signals during the fracture process,the formation and development of micro-cracks in the specimen were tracked,and the damage law of acoustic emission during the loading of three-point curved beam is obtained.A gray-point mutation model of acoustic emission is established.(3)In order to study the damage identification of reinforced concrete columns based on acoustic emission technology,a classification method based on gaussian mixture model(GMM)for corroded damage of reinforced concrete structures is proposed.In order to verify the proposed analysis model,the axial compression,small eccentricity and large eccentricity test were carried out for the reinforced concrete columns with the corrosion rate of 10%.By comparing and analyzing the classification results of GMM method and RA-AF correlation analysis method,the traditional RA-AF correlation analysis method can not define the coordinate ratio of RA value and AF value,and cannot truly distinguish the tensile crack and shear crack in the experiment.In the calculation process,the gaussian probability density function model of reinforced concrete and the calculation procedure of MATLAB are given.(4)In order to study the corrosion damage identification of reinforced concrete based on acoustic emission technology and reveal its corrosion mechanism,an area at the bottom of reinforced concrete beam plate was selected as the research object to carry out acoustic emission test of reinforced concrete specimen to accelerate corrosion.The acoustic emission signal characteristics before and after steel corrosion were studied.The acoustic emission parameter spectrum characteristic method is established to distinguish the component rust expansion failure from the loading failure.(5)In order to study the evaluation of corrosion and deterioration of reinforced concrete based on acoustic emission technology,the acoustic emission intensity analysis method was used to conduct quantitative analysis on the damage and deterioration of reinforced concrete beams accelerated by corrosion.The deterioration degree of corrosion was quantitatively characterized,and the acoustic emission monitoring workflow of reinforced concrete structures with time-varying damage was established. |
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