| The amount of concrete is currently growing, but in advocating environmental protection and scientific development today, the excessive exploitation of natural aggregate for concrete preparation, would cause irreparable damage to the environment, so the application of recycled concrete research has important significance. Due to the sources of recycled concrete and its preparing process is special, so it has a larger porosity and water absorption rate, and the strength, modulus of elasticity is low, impermeability, frost resistance, shrinkage and creep poor characteristics, restricted the development of recycled concrete. The six different recycled aggregate replace rate, different diameter of reinforcement concrete beam is divided into two groups, each test beam by the reinforcement of the same diameter, and contains a piece of ordinary concrete beam and a piece of recycled concrete beams, CFRP reinforced recycled concrete beam, researchers flexural strengthening performance. Then uses the software to carry on the finite element simulation analysis. The main research work and achievements are as follows:1. Material properties of CFRP and reinforcement method, discusses the constitutive equation of concrete, steel and CFRP and regeneration of CFRP reinforced concrete normal section destruction test, study the bearing capacity of the CFRP of recycled concrete beams, the influence of deflection, crack propagation, etc. After the carbon fiber reinforced beam test, the flexural bearing capacity was improved, and delay the appearance of cracks. Crack development speed is slow, the limit load of 25% ~ 85% shear bending section of inclined cracks developed rapidly.2, CFRP can effectively restrain the surface of the concrete beam cracks appeared and developed, and the regeneration of the reinforced concrete beam after crack deflection at a slower pace. With the increase of main rebar diameter, together with the reinforced CFRP bear the tensile stress at the bottom of the beam is better, the utilization of CFRP, beam stiffness loss. Beam cracking, bending tensile stress produced most resistance by CFRP, acceptor diameter has little effect.3, Using the theory of finite element analysis, finite element numerical analysis model is established for the test data, discussion of recycled concrete beams is simulated using the finite element unit types and failure criterion, is consistent with the test results of the numerical model. For comparison, the results of numerical simulation and experimental results verify the accuracy of the results of numerical analysis, respectively study stress and strain contours of reinforcement, carbon fiber cloth for regeneration of CFRP reinforced concrete beams is overall stress of the material.(1) In about 60% of the ultimate load, steel bar strain reaches the limit strain, steel yield at this time, since tensile stress will be borne by the CFRP.(2) The test after the carbon fiber reinforced beam and steel strain lagging behind the CFRP strain, with the increase of reinforcement ratio, degree of lag. CFRP under larger reinforcement ratio can exert its tensile properties, trabecular body stiffness loss reduction.(3) The first maximum principal stress of concrete cracking moment occurred near the load point alignment, the first maximum principal stress of concrete beam damage time occurred in the middle of the beam shear bending section position. So performance for cross cracks in the concrete cracking process development first, when loaded into the limit load of a quarter, bending shear crack rapid development, eventually because of destruction of the fracture and bent CFRP.4, The finite element model of longitudinal reinforcement parameters change, obtained with different reinforcement ratio of ultimate bearing capacity. According to the CFRP reinforced concrete structures subjected to bending bearing capacity calculation formula of CFRP reinforced recycled concrete compression zone height by modified formula:... |
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