Sensitivity Study for Computational Assessment of Prestressed Concrete Bridges

A current challenge for civil engineers is the conservation of existing infrastructures which includes maintenance, assessment and, if necessary, strengthening according to new code requirements. For the evaluation of the actual load carrying capacity and the remaining service life, detailed knowledge of the material properties and a realistic structural model is required. If necessary, the latter has to be adjusted for existing structures by in-situ measurements and inspections. In this paper, the structural behaviour of a concrete hollow box girder bridge is investigated by nonlinear analysis with a 3D finite element model. Based on these results a sensitivity study is performed by variation of material properties.

In a previous case study it was shown how eccentrically arranged traffic loads are inducted into the bridge-system and in which way the maximum stressing of a cross section could be calculated. For this, a 3D finite element model with the assumption of nonlinear material behaviour was used.

In a first step the redistribution of section forces in the transverse and longitudinal direction of the structural system due to nonlinear material behaviour is discussed. It will be shown in which way the force flow is influenced by nonlinear material behaviour in comparison to a linear elastic analysis. Second, the ultimate limit state (ULS) is discussed by means of a sensitivity analysis.

Finally, the influence of the used material assumption and the statical system in nonlinear calculations to the load bearing capacity is discussed. This might help in the judgement whether the service life of a bridge can be reached or a strengthening is necessary.