Probabilistic assessment of a road bridge based on inspection data - a case study emphasizing concrete strength

This contribution deals with the reassessment and application of probabilistic methods for the reliability analysis on the example of a 130 m long prestressed concrete bridge.The single-cell box girder bridge from 1965 carries a highway over a river and has three spans.The focus of this study is on concrete stress limitations and on the shear load bearing capacity based on the main tensile stress criteria.Most of the current codes are based on the semiprobabilistic safety concept, while certain national regulations explicitly allow the use of a fullprobabilistic verification format for the reassessment.The most significant developments and changes in the assessment framework are shown through a compilation of the standards over time.Based on the results from a finite element model and a semi-probabilistic assessment, the limit state for the probabilistic assessment of the shear capacity based on the main tensile stress criteria is derived.In this context, focus is put on the decompression proof.Relevant parameters are characterized and discussed.In view of the possibility to consider actual properties of existing structures through on-site data collection, parameter studies and sensitivity analyses are used to identify important measurement quantities.The concrete properties are derived from destructive and non-destructive material testing methods.In result, the in-situ concrete strength is higher than previously assumed and used to demonstrate the effects of including measured information in a probabilistic assessment.The normative and statistical background of the evaluation is explained.Finally, possibilities and limitations of the use of measurement data during the probabilistic assessment of infrastructure are highlighted and discussed.