On the very long term delayed behaviour of concrete

Several nuclear power plant containment buildings are made with biaxially prestressed concrete. In order to maintain enough prestressing in the structure, the delayed behaviour of concrete on the very long term should be correctly assessed. In this paper two questions are considered: is the very long term creep of concrete asymptotic or not? And how to deal with biaxial creep? The observation of the very long term deformations of containments, the deflections of concrete bridges and laboratory results of creep tests are used to give answers to these questions.