Equations are developed to depict the analytical relationships between the principal variables used in the design of a prestressed concrete girder. The formulas allow the designer to predict, with good accuracy, the number of strands and the required concrete release strength as a function of girder span and spacing. The given relationships apply to a large array of common box and /-beam sections. Although the approximate equations are not intended for final design, they nevertheless predict the parameters with an average relative error of less than 3 percent. Design examples are given to show how the formulas can be applied in practice.
