ABSTRACT
ABSTRACT Modern structural design standards, such as the Eurocode, follow a semi-probabilistic approach, in which the safety of a structure is controlled by partial safety factors. These standards are based on simplified models of load and structural performance, where approximations are made that typically lie on the safe side, leading to additional “hidden” safety. If these models are replaced by more sophisticated and potentially more accurate models, some of this hidden safety might disappear. Overall, increased accuracy is preferable, as it leads to a more economical and sustainable use of resources, but the question remains whether lost hidden safety leads to an overall reduction in structural reliability.
In this contribution, we investigate the hidden safeties in a three-field support reinforced concrete bridge under traffic load. Firstly, the bridge is designed by means of a more sophisticated traffic load model. For this purpose, the traffic load is modeled with simulation using measured traffic data and the resulting load effects are modeled with extreme value statistics. Finally, the reliability of the different design variations of the bridge are calculated with a full probabilistic approach. Thereby, four different definitions of failure are compared. The analysis results in a quantification of the hidden safeties associated with the traffic and the static model following Eurocode. Based on the results, we discuss implications for future regulations for structural design and assessment.
