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 with prestressed and nonprestressed reinforcement. It considers time-dependent effects on concrete and prestressed steel independently of the cracked or uncracked state. The analysis is performed at different intervals satisfying the strain compatibility between concrete and all layers of steel, as well as the equilibrium equation in sections subjected to normal forces and moments due to external loads. The development along the time of the creep coefficient, shrinkage, and relaxation loss is taken into account on the basis of prediction models and equations that may be extracted from codes and recommendations. Numerical examples in reinforced, prestressed, and partially prestressed concrete sections, including different loading conditions, are used to demonstrate the applicability of the proposed method.