Study On Equal Strength Substitution Method Applied To External Bonded Reinforcement Technology Of Concrete Beams

In modern society, the demands on the safety, applicability and durability of buildings of the people are increasing constantly. However, Building structure has been damaged and the service life has been affected, due to the influence of some factors, which contain the change of social requirements, the improvement of design standards and all kinds of natural disasters. Thus, it is significant to strengthen the buildings. Because of many disadvantages of traditional strengthening method, the method of reinforcement with bonding CFRP and steel plates are widely applied to the field of project reinforcement and the reinforcing theory and technology are formed. By using the method of reinforcement with bonding CFRP and steel plates, the calculate method of design code should be used by engineers, but some engineers used to using the equal strength substitution method, which is using the difference of reinforcement areas between before and after strengthening to calculate. So, it is significant to research the equal strength substitution method.Firstly, the paper described the strengthening characteristics and significance of reinforced concrete structure. Secondly, the strengthening methods of reinforced concrete structure were introduced and it was emphatically introduced about the characteristics and the internal and external current researches on the application of the external bonded reinforcement technology. Finally, the calculation methods of equal strength substitution and design code for strengthening concrete structure are adopted to calculate a lot of single-reinforced rectangular cross-section concrete beams by adjusting the initial reinforcement ratio and the strengthened moment design value, and then the applicability of equal strength substitution method applied to concrete beams with CFRP and steel plats are researched. The effects on application range of equal strength substitution method by the initial reinforcement ratio, the strengthened moment design value and the concrete strength grade are discussed. The dosage of CFRP and steel plates obtained through the comparison of the equivalent substitution and code calculation methods, which were used to obtain the relationship of initial reinforcement ratio, the area ratio of CFRP or steel plates calculated by the equal strength substitution and code calculation methods and the moment ratio of strengthened and initial ultimate moment. The result showed that equal strength substitution method was not applicable universally, which was feasible only within the scope of certain.