Description
For all buildings and structures a sufficient safety standard is essential. In the basic building codes like the EN 1990 failure probabilities are defined for different buildings members and applications. Materials as well as actions are characterized by safety factors to fulfil the failure probability requirements and to enable in this way a safe design. But materials with time dependent properties can complicate this process.
In this paper different ways to determine the resistance of these materials based on long term tests are presented. For this reason it is important to define characteristic values also for the long term resistance, if the code is based on a semi-probabilistic safety concept.
In addition different safety concepts for these materials are discussed regarding technical, economical and practical aspects. As examples the approaches from the EN 1992-1 Annex R, the approach from ACI 440 and CSA and the German approval abZ 1.6-238 are evaluated. A combined performance based approach for a higher economical efficiency with the same proven level of safety is presented at last. This is all shown with practical values and examples.
