Comparative study of the prediction of delayed strains using the next-generation Eurocode2 with measurements on structures

Abstract

In structures where prestressing plays a vital role, predicting stress losses is essential to demonstrate their robustness. After presenting the equations of the next-generation Eurocode 2 (EC2), the delayed deformations of the containment vessels of EDF nuclear power plants are predicted. In the first step, the parameters of the laws are recalibrated based on the measurements of the containments, considering a temperature higher than 20 °C. The application to 17 containments allows for the definition of a safety coefficient to be applied to shrinkage and creep to ensure that the delayed deformations evaluated for the design will be conservative. In the second step, the parameters of the equations of creep and shrinkage are calibrated on laboratory results, and an analytical model using these parameters is applied to 5 containments. All the results show that it is possible to predict the behavior of prestressed structures provided that the parameters of the equations controlling the delayed deformations are calibrated either on measurements of these structures or laboratory tests. Considering the variability of concretes, safety coefficients are proposed to guarantee that the predicted deformations cover 95% of the deformations of concrete of a given strength.