Influence of detailing on shear in existing concrete viaducts

For a lot of existing concrete bridges and viaducts a sufficient safety against shear failure can be proved with an in depth structural assessment based on the present design regulations and taking into account hidden capacities, such as an increase in strength in time in the actual structure in regard to the design strength. However some structures still have a lower reliability value. As an example of this, in this paper a few bridges and viaducts, on which the road-capacity had to be increased, are presented. It is illustrated that, with the knowledge of today, the detailing of prestressing or reinforcement and changes of cross-sections in these structures causes lower reliability values as designed.