Flexural Performance Of RC Beams Strengthened With Polyester FRP Composites

Fiber Reinforced Polymer/Plastic(FRP)has so many advantages,such as light-weight and high-strength,good durability,construction convenience.FRP is developing faster and faster in civil engineering.And FRP strengthened reinforced concrete beams have been applied in structures.FRP reinforcement of reinforced concrete beams can improve the bearing capacity and ductility and enhance the seismic performance simultaneously.Nowadays,carbon/glass fiber materials are more extensive to be used in strengthened beams.However,the traditional man-made fiber has a bit deficiency in cost,environmental demand and sustainable development.Therefore,polyester fiber will be a better choice in future research,and gradually replaced the traditional man-made fiber to apply in structures in order to respond to the national development strategy,that is "resource conservation" society and"environmentally friendly" society,and development theories of green building.In this thesis,polyester fiber is used as FRP substrate,and the flexural performance of reinforced concrete(RC)beams strengthened with Polyester Fiber Reinforced Polymer/Plastic(PFRP)is investigated by experiment.The main research content is as follows:(1)Mechanical property tests of materials used in the experiment were conducted,including mix design and compressive test of concrete,tensile test of steel bar and uniaxial tensile test of PFRP,which provide basis for the experimental study and theoretical analysis of the RC beams strengthened with PFRP.(2)Two RC control beams and six PFRP strengthened RC beams were constructed and tested under four-point bending.The flexural performance of beams was analyzed considering reinforcement ratio,fiber layers and pre-splitting as the parameters.The load-deflection relationship of beams,load-strain relationship of reinforcement,the load-strain relationship of PFRP,ductility of beams,are all analyzed in detail.It's shows that compared with the control beams,the strengthened beams experienced significant enhancement in ductility,ultimate load and deflection due to the PFRP reinforcement;The crack of PFRP beams is more dense and the energy absorption is more larger.(3)Based on the mechanical property tests results in this thesis and the material constitutive laws that already exist,the flexural performance of PFRP strengthened RC beams is analyzed.The calculation formula model of bending capacity of RC beams strengthened with PFRP is put forward according to different failure modes.And the conservative calculation values of the ultimate load matched well with the experimental ones.