Study On Fatigue Behaviour Of Sea Sand Concrete Beam With BFRP Bars

The load bearing components of reinforced concrete has been widely applied in recent decades,due to long time by environmental factors affect the problems of corrosion and durability.the combination of the composite fiber reinforced(FRP bars)and the sea sand concrete not only can solve the problem of reinforcement corrosion,and improve the durability of the structure,but also can resolve shortage situation of the river sand resource.it conform to the sustainable use of resources.In recent years,FRP bars has got extensive as a new type of material.FRP bars with high strength properties and is not sensition to the chloride ion,it provides favorable conditions for the use of sea sand concrete,to achieve a major breakthrough in the about never use sea sand concrete as aggregate.solving the problem of corrosion can greatly improve the service life of structure,and greatly reduces the maintenance of infrastructure.The stability of FRP bars has good application prospect.This test with the reinforcement stress of the FRP bars as untreated sea sand concrete beam,and sea sand concrete using C50,and made of two kinds of size.Beam of small size comparing with two reinforced concrete beam.Researching different stress level,comparing with different sizes and comparing reinforced concrete beam,the impacts of these fators on the beam failure pattern,racking load,deflection,the law of the development and fatigue life,etc.By studying the fatigue performance of sea sand concrete beam with BFRP bars,the process of experiment measure deflection,the strain of BFRP bars,crack of beams,the ultimate bearing capacity,the strain of concrete,and use the method of regression the S-N curve.The results show that under the condition of different stress level,the increasing of the rate of deflection increasing with the stress level enhances,and the width of the crack increasing gradually,and compressive zone of concrete appear cracks in advance;To the comparison of the beam of two size found that deflection and BFRP bars is similar to the growth regularity of reinforcement,but a slightly different crack width and crack spacing;Compared with reinforced concrete,the deflection of sea sand concrete beam with BFRP bars change a bigger,and crack width and crack spacing is bigger,this is mainly related to the elastic modulus of BFRP steel smaller.Finally,according to the requirements of Technical Code For Infrastructure Application of FRP Composites,by comparing the regulations of conclusions with the test results,and put forward the proposal about fatigue performance of the sea sand concrete beam with BFRP bars.