Influence of variable actions on permanent through–cracking and deflections of prestressed concrete structures

Designers of prestressed concrete structures need simple and effective serviceability design criteria. Emphasis must be placed on the behaviour under permanent loads, but the progressive damaging of the structure under variable traffic loads and thermal actions needs to be taken into account. These variable actions can lead to residual permanent through-cracking of the structure and leave irreversible consequences. Checks at the permanent state must thus account for residual cracking and deformations that are added to the effect of permanent actions. This paper considers these issues in the context of providing sensible design rules for dealing with the main phenomena which govern the serviceability behaviour of this very complex material.