| Along with China’s economic developing, the reinforced concrete structures which have been subjecting fatigue load for a long time,such as bridge, crane beam, high-speed railway and so on, are widely used in the process of industrialization.After beening used for a few years, these structures will need to be reinforced on account of fatigue damage. CFRP sheet with good properties and convenient operation is widely used in this type of reinforcement engineering. It is a key factor that the effectiveness of the concrete beam reinforced by CFRP sheet under fatigue loading determined by the interface bonding of CFRP sheet and concrete. So far, the research of scholars at home and abroad mostly focus on the interface bonding of CFRP sheet and concrete under the static load and the fatigue property of CFRP sheet reinforced an undamaged concrete member. The research on the interface bonding properties of CFRP-demaged RC beam under fatigue loads is still blank.Taking damage degree of the original beam and fatigue load amplitude as test variable to study the influence of this two variables on the interface bonding properties of demaged RC beam reinforced with CFRP under fatigue loads. The followings are the main contents of this study:(1) The stiffness damage coefficient of five test beams are calculated according to the existing research results and test data,which is used to determine initial damage degree of the test beam.(2) By considering damage degree of the original beam and fatigue load amplitude for the influence of the interface bonding of CFRP sheet and concrete,the fatigue testing program of CFRP sheet reinforced the reinforced concrete beam after damnification was designed, the experimental research is conducted.(3) The experimental phenomena of test beam was observed from the beginning of loading to the final destruction.Crack of the reinforced concrete beam after damnification and the development process of stripping cracks of the interface of CFRP sheet and concrete was observed.And the fatigue life was recorded. The influence of this two variables on the development of Stripping cracks and fatigue life of test beam was researched.(4) The test data was analyzed.The curves of the strain of CFRP sheet at loading point and telos variation with load cycles and the curves of CFRP sheet strain distribution along the bond length in different cycles and the curves of test beam’s deflection and strain of tensile steel bar variation with load cycles were plotted. The influence of this two variables on the interface bonding properties of demaged RC beam reinforced with CFRP under fatigue loads was studied.(5) According to the basic theory of bond slip, bond stress-slip curve of feature points of Pure bending section and shear moment regions of test beam. The influence of this two variables on the interface bond-slip relationship of CFRP-demaged RC beam under fatigue loading was studied. |
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