STRAIN-STRESS ANALYSIS OF REINFORCED CONCRETE BEAMS STRENGTHENED WITHOUT UNLOADING BY EXTERIOR REINFORCEMENT

摘要

When applying strengthening by exterior reinforcing, the problem assessing of the remaining carrying capacity of the member being strengthened and estimation of the actual stress in the reinforcement placed in concrete of the tensile zone of the member is to be solved. In the present paper a method for the analysis of the flexural concrete members strengthened by exterior reinforcing bars is proposed. The method allows designing the exterior reinforcement by taking account of the remaining carrying capacity of the member being strengthened. Moreover, the method proposed enables one to assess a redistribution of stress between the originally placed reinforcement and the exterior reinforcement used to strengthen the member. The redistribution of stress has a considerable influence on the carrying capacity of the member as well as on its bending stiffness. Opposite to other methods suggested in the literature and used for the analysis of the flexural members strengthened in the way described above, the method proposed in the present paper allows one to take account of the plastic deformations of concrete and steel in the member being strengthened. In addition, the proposed method is less complicated to apply when compared to methods suggested to date. The proposed method was verified by a series of experiments with simple reinforced concrete beams.