Experimental Study And Theoretical Analysis On Concrete Beams Reinforced With Different FRP Bars Blended

With the advantages of high tensile strength,corrosion resistance andelectromagnetic shielding,Fiber reinforced polymer can be used to replace the steel barto solve the problem of durability effectively in concrete structures,more over,it can alsobe used for military building which with anti-electromagnetic interference.However,due to the linear-elastic stress-strain relationship of FRP tendons,FRPreinforced concrete beams show brittle fracture modes,and its ductility performance ispoor. In view of this,this paper proposes a hybrid reinforced theory,that means combinetwo kinds of FRP tendons which have a large difference in ultimate deformationtogether as a beam member muscle force. the FRP with smaller ultimate deformationfracture before the greater one during loading process,and shape a mutation of stiffnesswhich similar to the loading process of reinforced concrete,thus bearing capacity anddeformation capacity after mutation point can be regard as ducitility reserve.This article begin from three aspects: theoretical derivation,finite elementsimulations and experimental verification to verify flexural behavior and ductility ofhybrid FRP reinforced concrete beams. The author focus on CFRP bars and GFRP barsto analyses the calculation method,the force ducitility characteristics and influencingfactors of hybrid FRP reinforced beams. In addition, it also demonstrate ducilityperformance improvement relative to ordinary FRP reinforced concrete beams.The main conclusions are achieved as follows:①hybrid FRP reinforced concrete beam has clearly distinguished from ordinaryFRP reinforced concrete beam in failure modes. Rupture of CFRP bars can really bringbeams a secondary stiffness,and deformation capacity significantly increased after therupturing,which produce more significantly omen before damage. This kind ofreinforcement arrangement can promote ductility performance and security of FRPreinforced beams more obvious.②calculation formulas of cracking moment,ultimate moment and deflectiondeduced in this paper can accurately describe the real force state. It is noteworthy thatthe formula of deflection can only be used to calculate deflection polygon under normalservice condition and it will lead larger error if used to calculate ultimate deformation.③established a equation to calculate the maximum mixing ratio, the greaterpropotion of broken ribs,its ducitilty is better. but at the same time,a overlarge propotion will reduce ultimate carring capacity, on the other hand, a insufficientpropotion can decrease the defromation ductility. Reinforcement ratio have a relativelyobvious influence on defromation ductility instead of bearing capacity ducitility.④propose a theory that treat the point of stiffness turning as the design target ofhybrid FRP concrete beams, thus, the minor flexibility and the increasable bearingcapatity of this state can both meet the design requirements.