Three-dimensional rupture analysis of a prestressed concrete pressure vessel including creep effects

This paper describes briefly the results obtained from a nonlinear analysis up to rupture of a PCRV taking into account creep effects. This analysis aims mainly at evaluating the influence of the redistribution of stresses due to the rheological behavior of concrete on the rupture pressure of a PCRV. First, the method of nonlinear analysis for creep and rupture is described briefly. The mathematical model, of a general application, is based on the finite element method, utilizing the isoparametric elements. Nonlinearities are introduced by the use of iterative techniques. It allows us to predict, within satisfactory limits, the behavior of massive prestressed concrete structures loaded up to destruction. The use of classical parameters for definition of the physical characteristics of materials for formulating the constitutive laws makes the model particularly interesting for practical applications. The analysis of the PCRV for a gas-cooled fast reactor developed by the Swiss Federal Institute for Reactor Research is also presented. This PCRV has large cavities in its walls to house direct cycle gas turbines and other mechanical equipment. First, the creep analysis is carried out taking account of the envisaged construction schedule and the loading during the testing period and finally during the normal exploitation of the PCRV. Proceeding from the state of stress obtained as such the rupture analysis is carried out for a sudden increase of internal pressure and temperature gradient due to a hypothetical accident.