Partially Prestressed Concrete Structures

Abstract

A method is presented for prediction of stresses and strains of partially prestressed concrete structures. Members are assumed to be uncracked under permanent loads, but cracking can occur under transient live load. A superposition procedure is employed to calculate the time‐dependent effects of various loadings including the initial prestress and the changes in stress in concrete and steel due to creep and shrinkage of concrete and relaxation of prestressed reinforcement. The analysis accounts for the presence of non‐prestressed reinforcement and gives the time‐dependent values of axial strain, curvature and stress in concrete, prestressed steel and non‐prestressed steel. Numerical examples are included for calculation of the curvatures in uncracked and cracked partially prestressed beams and the curvature values are employed to determine the deflections.