TIME-DEPENDENT ANALYSIS OF REINFORCED AND PRESTRESSED CONCRETE MEMBERS

A new step-by-step method is proposed that allows the determination of the history of strain and stress distribution in concrete sections wi th prestressed and nonprestressed reinforcement. It considers time-dep endent effects on concrete and prestressed steel independently of the cracked or uncracked state. The analysis is performed at different int ervals satisfying the strain compatibility between concrete and all la yers of steel, as well as the equilibrium equation in sections subject ed to normal forces and moments due to external loads. The development along the time of the creep coefficient, shrinkage, and relaxation lo ss is taken into account on the basis of prediction models and equatio ns that may be extracted from codes and recommendations. Numerical exa mples in reinforced, prestressed, and partially prestressed concrete s ections, including different loading conditions, are used to demonstra te the applicability of the proposed method.