Structural Reliability and the Partial Factors for Materials

Abstract

Structural Eurocodes introduce an important concept, the “structural reliability”. The Albanian code “KTP – Kushtet Teknike të Projektimit”, does not define this term. From this, several difficulties might arise, ranging from the basic understanding of Eurocodes to the practical use of them, including important aspects such as “the determination of partial factors” into the National Annex of a country adopting Eurocodes. The partial factors have a considerable influence on safety and economy, which is the reason why they have historically had and continue to have a sort of political and strategic background. This paper introduces some aspects of Structural Reliability through a study focused on concrete strength. Test results from already built structures in Tirana have been used for this purpose. How “reliable” are the structures being designed in Albania using the partial factor method with the recommended partial factors? The answer is not easy; a very large number of tests is needed in order to make an assessment towards the answer. Trying to give a contribution to this matter, this paper describes the results obtained for a reinforced concrete beam when structural reliability concepts are considered explicitly in design. Comparison is made with the structural analysis using the partial factors recommended in Eurocode, with focus on partial factor for concrete.