Shear Capacity Analysis of Reinforced Beam Strengthened with Fiber Reinforced Polymer Considering the Feature of Rebar Corrosion
|Course||Bridge and Tunnel Engineering|
|Keywords||Basalt fiber cloth shear reinforcement mechanical properties localcorrosion transformation of damage system|
Reinforcement corrosion in concrete is the major cause of performance degradation of concrete members, but the current research on the mechanism of reinforcement corrosion and its developing law is not clear. Although a large number of engineering test reports show that, reinforcement corrosion morphology can be roughly divided into uniform corrosion and local pitting corrosion. The local pitting corrosion results in stress concentration which will significantly affect mechanical properties of components, but system test and theoretical analysis about it have not yet been carried out. The corrosion of reinforced concrete member in engineering must be timely strengthened. Basalt fiber cloth, as a new kind of reinforced material, with its lightweight, high strength, high temperature resistant, corrosion resistance as well as the low price has an advantage in the field of service structure reinforcement engineering. In the past decade, scholars at home and abroad took off a lot of experimental research on FRP cloth material performance and mechanical properties of strengthened concrete beam, and established calculation methods and design disciplines on this basis. Because shear failure is more uncertainty and discreteness, adding the lack of research on reinforcement corrosion morphology and durability of fiber reinforced effect in long term, shear capacity analysis model of reinforced concrete member with corrosion damage strengthened by FRP cloth has a larger error. In view of above problem, this paper carried out detailed research work is as follows:(1) Samples of corroded steel bars in reinforced concrete members is prepared through laboratory accelerated corrosion in erosion environment. Statistical analysis in allusion to local corrosion characteristics is carried out. Degree of corroded steel bars and relationship among corrosion pit morphology is studied, combining mechanical properties test on corroded steel bars. A more reasonable corrosion degree classification method and more accurate performance evaluation indicators on corroded steel bars is set up. Degradation law of corroded steel bars and effect on the mechanical behavior of corroded steel bars by corrosion pit parameters is studied through tensile test. Mechanical performance degradation model of steel bars is established.(2)3D finite element model of corroded steel bars is established, and is compared with the test results to verify the validity of the finite element model. corrosion pit shape parameter about steel bar in Class Ⅱ is studied, including the effect on the mechanical behavior of reinforcing steel bar by corrosion pits’depth, width, length and the interaction between adjacent corrosion pits, and the relationship between the stress magnification coefficient/uneven stress coefficient and corrosion pit parameters is raised.(3) Different initial degradation degree and influence of different reinforcement material against shear reinforcement effect are analyzed through static test on10shear reinforcement beams in different corrosion degree and the subsequent degradation degree strengthened by FRP cloth. Based on existing model and test results of FRP shear reinforcement concrete beam, corrosion of steel bar and the long-term erosion against performance and failure pattern of components after shear strengthening is analyzed, to provide more accurate prediction model for shear bearing capacity after strengthening by FRP.