Experimental Study On Bond Performance Of Steel Bar And Steel Fiber Concrete In Hightemperature Environment Of 500MPa

Steel bars and concrete materials are used in large numbers in contemporary building structures,the properties of the two materials are fundamentally different,but they can work stably together in the building structure,which is inseparable from the good and reliable bonding between them.The firm bond can make the steel bar and concrete closely combined,and can play a good role in the complementary effects of the two materials.As our country’s economy progresses and people’s quality of life is promoted,people’s demends for the stability,reliability,and disaster resistance of their own residential buildings are becoming stricter and stricter.Steel fiber concrete is a very promising material for contemporary construction,according to research,steel fiber relies on the good tensile strength of its own material,the tensile performance of the concrete material is significantly promoted,make up for the lack of material properties of concrete materials.As steel fiber concrete is researched and promoted in the utiliation field,the principle of steel fiber concrete and on-site applied construction technology are rapidly developed,provides a theoretical basis and applied technology basis for the popularization and use of steel fiber concrete.Aiming at the rapid development and application trend of steel fiber concrete in the contemporary civil engineering industry,further deepen the relevant experimental and theoretical research on steel fiber concrete and steel bars,which is more significance.This article will conduct a central bond pull-out test on 500MPa grade steel bars and steel fiber concrete specimens,research its bonding properties.The main work of this paper is as follows:(1)In this paper,The test variables are the type of concrete,the amount of steel fiber per unit volume,and the temperature condition,according to the test variables,a total of 18 ordinary concrete and 54 steel fiber concrete cube specimens were designed and completed in the center pull test.(2)The improvement of compressive and splitting resistance of concrete with different steel fiber content per unit volume is analyzed.The damage of various kinds of steel fiber concrete specimens under different high temperature environment was observed.The damage morphology and crack development of concrete specimens with different steel fiber content were observed after the central pulling test.(3)Study the failure phenomena of steel fiber concrete and ordinary concrete specimens at room temperature,after high temperature,and at high temperature respectively,the relationship between the bond stress and relative slip between steel bar and ordinary concrete and steel fiber concrete is summarized,and the bond-slip(τ-s)relationship curve of the damage process of each specimen is drawn.(4)Compare the regular characteristics of the bond-slip(τ-s)curve of each group of tests at room temperature,after high temperature and under high temperature,analyze the damage change law of the bond performance between ordinary concrete and steel fiber concrete and steel bars,by establishing the relationship between bond damage variables and relative slip,study the variable correlation between bond stress and slip.The relationship between related variables were fited and analyzed by ORIGIN software,fitting to obtain the bond-slip(τ-s)constitutive relationship equation between steel bar and steel fiber concrete,and the calculation error is approved.(5)In the process of studying the bond-slip injure between steel bars and steel fiber concrete,finite element software is used.The calculated value of the bond stress and slip value calculated by the fitting formula,input it into the numerical simulation established by ABAQUS finite element analysis software.The stress distribution during the process of pulling out the steel bar from the specimen and the correlation change between the stress and the amount of steel slip,compare the data obtained from the test simulation with the data collected from the test,the simulation test further verifies the reliability of the bond-slip constitutive relationship obtained.