| Abstrakt: |
Eq. (18-3) of ACI 318-77 is an approximate equation for fn the stress in bonded prestressed reinforcement at nominal moment strength. It was originally proposed by joint ACI-ASCE Committee 423 in 1958 in "Tentative Recommendations for Prestressed Con-crete. " A study was made of the influence on the accuracy of Eq. (18-3) of the use of (a) prestressing steel for which fpy, = 0.90fpu, (b) high-strength concrete, (c) additional unprestressed flexural tension rein-forcement, (d) compression reinforcement, and (e) use of a slender T-section beam rather than a rectangular section beam. A modified version of Eq. (18-3) was developed that takes into ac-count the above factors and yields values of fpsin closer agreement with values obtained from an analysis based on simultaneous satis-faction of compatibility of strains and equilibrium of forces. This modified version of Eq. (18-3) has been included in ACI 318-83. Ke [ABSTRACT FROM AUTHOR] |
