This paper is based on the Swiss experiences with partial prestressing and reflects both research and design practice. This experience has been gained primarily with post-tensioned structures and began in 1968. A simple method of design is proposed that allows a smooth transition from reinforced to fully prestressed concrete. Depending on the area of prestressing steel selected, the area of additional nonprestressed mild steel must be varied. Major emphasis is given to the meticulous detailing of nonprestressed reinforcement (and especially to narrow bar spacings) to ensure serviceability and crack width limitations. In addition, the desirability of including a certain minimum amount of nonprestressed reinforcement, even for fully prestressed structures, is emphasized and the influence of the degree of prestress on some key parameters is discussed. Finally, the design method is illustrated with an example of a three-span continuous highway bridge.
