The Study On Impact Of Fatigue Damage Evolution For Post-bearing Capacity Of Concrete

Concrete is one of the indispensable materials in the modern construction. As thebuilding material develops in the direction of being more economic, energy-saving,reliable, more precise requirements are laid on the preparation and manufacture ofconcrete. Concrete is a composite material composed of gelatinization and the mixture ofaggregate and water. Aggregate that a filler material of concrete, accounting for70%~80%of total volume of concrete, has an important influence and function in the concreteperformance.With using additive fatigue and uniaxial compression test in this thesis, the influenceof aggregate size on the mechanical properties of concrete is studied. In the process ofconcrete specimen preparation and choice, this experiment using the ultrasonic measuringmethod and static load strength statistical analysis of deficiency is to reduce the discretionin the process of coagulation test. The ultrasonic flaw detection and digital specklecorrelation method traces detection of fatigue damage loading process, getting ultrasonicdamage accumulation amount range in the different aggregate size of concrete. Fatiguetest is established digital speckle image processing methods, it got different aggregateparticle size effect on the amount of fatigue damage accumulation. The affection of theamount of the damage accumulation induced by the different aggregate particle size hasbeen gotten by the method of digital speckle image processing in the fatigue test. Thispaper compared the influence degree of the damage arise from the horizontal displacementand vertical displacement by choosing a surface displacement field contour map in aloading phase.A test platform for uniaxial compression test and high speed camera was set up in thespecimen of the uniaxial compression test of late. It is proposed that strain localization ofthe deformation field of concrete specimen could be used to describe the damage ofmaterial, experiments are performed on concrete that results show the feasibility of thismethod. The index can better predict the extent of localization in concrete specimenbearing, and using this method to compare the different aggregate surface change laws ofstrain field. The results show that: with the increase of aggregate diameter, concrete lesspressure on the whole, the surface displacement vector mean the faster the rate of change,the concrete localization band appeared earlier. The increaser of aggregate diameter, destroy the dissipation energy is smaller, its effect on the static load is greater than thefatigue load by compare different aggregate at different loading stages of dissipation ofenergy in the specimen throughout the loading process.