Experiment And Theoretical Research On Flexural Performance Of Damage Rc Beams Strengthed With Near-Surface Mounted Strips

Near-surface mounted CFRP is a new reinforcement method. Near-surface mounted CFRP is a reinforcement method to advance on the surface of the components that need to reinforce the slot, and then put the CFRP strips into slots to improve the mechanical performance of the component. Compared with the surface stick method, near-surface mounted CFRP has the advantages of low dosage of materials, corrosion resistance, applicable to the uneven surface of the component, and more effective component force, suffers accident load is not easy to damage, etc.This paper designs17RC beams, the beams when considering the reinforcement ratio, amount of CFRP and damage as test parameters. By measuring test of cracking load, yield load, ultimate load, deformation, cracks and strain of concrete, steel bar, CFRP strip. Analysis the failure mechanism of RC beams, the influence of the cracking load, yield load, ultimate load and stiffness is researched by reinforcement ratio, amount of CFRP and damage, and then analysis the strengthening effect between the external bonded and Near-surface mounted. On the basis of experimental study, the ultimate capacity, cracks calculation method and deflection calculation method for theoretical research. The main research work is as follows:1. Study on flexural performance of Damaged RC beams strengthed with Near-Surface Mounted CFRP strips, analysis the failure mechanism of RC beams, the influence of the cracking load, yield load, ultimate load, stiffness is researched by reinforcement ratio, amount of CFRP and damage.2. In the existing model for calculating the ultimate bearing capacity of CFRP reinforced structures, on the basis of calculated according to the basic theory of reinforced concrete beam bending bearing capacity and discusses calculation method of bearing capacity of reinforced concrete beam.3. Using the principle of minimum stiffness, analysis of the stiffness RC beams with NSM under normal use, and midspan deflection calculation formula is derived. 4. According to theory of crack of RC beam, calculation formulate for average cracks distance and maximum crack width are derived.Through the experimental study and theoretical study, draw some conclusions as follows:1. Failure modes of RC beams with NSM were mainly affected by the amount of CFRP and reinforcement ratio; NSM can effectively improve the characteristic load; Deformation of the RC beam with NSM was mainly affected by amount of CFRP and initial load.2. Without considering the CFRP stripping failure situation, establish a formula of the bearing capacity is derived, the calculation results with the theoretical results fit well.3. Calculate the midspan deflection with the calculating formula of the deflection with is derived under the normal use, the calculated value and the experimental results fit well with.4. According to the theory of RC beam crack calculation shows the normal use of the reinforced beam under the average crack spacing and maximum crack width calculation formula. By comparing the test data and calculated values and experimental values are smaller.