Structural Assessment of a Post‐Tensioned Box Girder Bridge affected by Concrete Creep

The behavior of post‐tensioned concrete bridges is often influenced by time‐dependent phenomena, such as relaxation of prestressing steel, creep and shrinkage of concrete. For bridges built using the balanced cantilever method, the evolution of time‐dependent phenomena during the construction phase must be carefully considered. In common practice, the assessment of the structural safety of this bridge typology is a complex task due to the numerous factors and uncertainties involved in the evaluation process. Numerical models can be adopted to perform structural analyses at successive phases over bridges' lifetime, while destructive and non‐destructive evaluation methods are used to gather information to ensure that the numerical model matches the actual behavior of the bridge. In this context, this paper presents the structural behavior assessment of a multi‐span post‐tensioned box girder bridge with vertically prestressed internal joints. A numerical model was constructed to investigate on the effect of creep and construction phases on the actual stress/strain conditions of the bridge. To reduce model‐based uncertainties, compression tests were carried out on concrete cores extracted from the structure and the results of static load tests were used for model validation purposes.