Flexural Strength Analysis of Prestressed Concrete Beams Reinforced with External Tendons

摘要

Recently in Japan, many reinforced concrete structures (RC) as well as prestressed concrete structures (PC) damaged by chlorides attack have been repaired by various methods. On the other hand, even though RC/PC members which are not damaged encounter the grade-up scheme, since the design load for these structures have increased. External prestressing method, which is simple and easy to construct is considered to be one of the most suitable method to improve the existing condition. However, the estimation of ultimate strength for the structures with external prestressing tendons has not been clearly specified in the design. In this paper, the authors have discussed the efficiency of increasing ultimate flexural strength of PC beams reinforced with external cables. The ultimate flexural strength was calculated on the assumption that the elongation of the cable at the ultimate state is equal to that of the concrete which is in the same location as the cable. The change of external cable eccentricity caused by the deflection of the beam was also taken into account in this analysis.