Design Prestressed Concrete Section for Flexure

The design of a prestressed section with assigned efficiency for members working for flexure is presented in the form of an analytical method which does not require iteration, use of tables or graphs or a solution of simultaneous equations. The section depth, the cover of tendons and effectiveness of prestress have to be evaluated at the start. The result of calculations can give a section fully stressed, or with stresses at the service stage satisfied exactly in case of a member with limited depth, or even a section with excessive capacity when it is desired. The section dimensioning is made in an approximate way, but required accuracy is easy to achieve. The introduction of the coefficient of dead load moments ratio in sections critical at transfer and at service allows it to take care of the differences between post‐tensioned and pretensioned members with constant eccentricity tendons or with harping points, without the necessity of providing appropriate allowances in stresses. Use of the method is illustrated by examples of design of a post‐tensioned member and a pretensioned one with harping points.