Experimental Research For Reinforced Concretr Beam Strengthened With Prestressed CFRP-lamina

Due to man-made or natural factors and the improvement of standards,many old bridges and houses need to be reinforced.However,the traditional strengthening methods have obvious defects,and the reinforcement effects are not ideal.Withtheappearance of carbon fiber reinforced composite materials(CFRP),the use of its good performance drawn attention of the construction industry,CFRP board has many advantages,such as light weight,high tensile strength,durability,aging resistance,stress relaxation and so on,and CFRP board is widely applied to the structure of the reinforcement in maintenance.CFRP boardreinforcement method is to reinforce the efficiency high characteristic,can significantly delay crack,control crack,and improve the bearing capacity.Because of past research of all kinds of high difficulty,low level of prestressed anchorage reinforcement construction defects,the engineering application of this technology is limited.Based on the existing tensioned anchorage devices,this paper has independently developed two sets of tensioned anchorage devices,whose performance is reliable and operation is simple(need to slot anchorage MJ-1,no need slotted anchorage MJ-2);This paper has designed the contrast beam,the beam with nonprestressed CFRP plate(MJ-1),the beam with prestressed CFRP plate(MJ-1)and the beam with prestressed CFRP plate(MJ-2),then contrasted the flexural performance of the four experimental beams.The main contents and results are as follows:1.Two sets of tensioned anchorage device are developed,which are reliable and guarantee the CFRP and beam work in phase.The beam with MJ-2 anchorage with no groove will not wake the original section.So the MJ-2 is more practical.The paper has concluded the construction technology and operation process of the CFRP plate,which offeres reference and technical support for the application of prestressed CFRP plate in the actual engineering project.2.The factors causing the loss of prestress of CFRP plate are the resistance between anchorage device,tension jig retraction and deformation,stress relaxation of prestressed CFRP plate and concrete shrinkage and creep back.And the retraction of the fixture is the major cause of instantaneous loss of prestress of CFRP plate.3.Experiments are conducted to investigate the flexural behavior of the contrast beam,the beam reinforced with nonprestressed CFRP plate,the beam reinforced with 40%prestressed CFRP plate(slotted)and the beam reinforced with 40% prestressed CFRP plate(not slotted).This paper has analyzed the influence of non prestressed and prestressed CFRP plate on the crack development and distribution,the bearing capacity,deformation of the component and bending stiffness,compared the strength of CFRP board in each stage,and laid the foundation for the application of the prestressed CFRP plate(not slotted)in the engineering.