Acoustic And Electrical Characteristics Of Thermal Damage And Failure Precursor Response Of High Temperature Concrete

In order to study the change of mechanical properties of concrete under high temperature and the precursory signal characteristics of structural instability,the electric signal monitoring system of high temperature concrete and the experimental system of high temperature concrete loading are established,The change characteristics of surface potential signal of concrete sample under thermal load are studied,and the mechanical behavior,surface potential and acoustic emission of heat treated concrete are analyzed,The critical slowing characteristics of Acoustic and electrical information of concrete damage are studied,and the precursory signal characteristics of concrete failure are obtained.The findings are as follows:(1)By using the monitoring system of surface potential signal in the process of programmed temperature rise of high temperature concrete,it is found that obvious surface potential signal will be produced in the stage of programmed temperature rise and constant temperature of concrete,the analysis shows that the contour distribution of the surface potential signal on the same observation surface at different time is higher in heating stage than in constant temperature stage.(2)To test the acoustic and electrical signals of the damage and fracture process of heat-treated concrete under load,and to compare and analyze the changing characteristics of the acoustic and electrical signals of concrete under different temperatures,found that the AE signal can reflect the whole damage condition of the specimen well,and the acoustic emission signal can reflect the whole damage condition of the specimen,the surface potential field can reflect the damage area of the specimen.The research results are important to evaluate the damage degree of high temperature concrete and to judge the stability of the structure.(3)Analyzing the Acoustic and electrical signals of the concrete during the stage loading process after different temperature by the critical slowing method,and comparing and analyzing the precursory characteristic points of the accumulative counting curve of concrete acoustic emission signals,the results show that the precursory information points can reach 90% of the peak load,which is very important for the identification of concrete damage precursor signals.This dissertation contains 26 drawings,3 tables and 74 references.