Time-dependent strains of prestressed concrete containment vessels: Validation of analytical model by real-world data

Abstract

Nowadays, for the containment of nuclear reactors, the prestressed concrete containments (PCCs) are most often used for their high resistance to both design and accidental loads. When designing a safe and effective PCC, an accurate prediction of prestress losses is of vital importance. One of the most considerable prestress losses is caused by the time-dependent strain due to creep and shrinkage of concrete. Thus, in the preconceptual design phase, a tool for making relatively simple but safe prediction is required. When designing a PCC in particular, the situation is complicated by the fact that the PCC is a mass concrete structure exposed to increased operation temperature which affects the creep and shrinkage of concrete greatly. Bažant́s widely accepted creep and shrinkage model B3 with the extension for elevated temperature (called B3T) allows to take into account increased operation temperatures for thick concrete elements. However, this model is not primarily aimed at mass structures at elevated temperatures, and its usability for prediction of creep and shrinkage of concrete in these structures should be verified. In this paper, the authors analyse the usability of this model for the PCCs by comparing real-world measurements gathered from publicly available sources for 13 types of containments (31 structures in total) with B3T model predictions. The analysis shows that the B3T model provides a safe estimation of creep and shrinkage in 28 out of the 31 structures. In the remaining three cases, an unsafe result was obtained, probably due to a nonstandard course of the construction schedule; however, the inaccuracy of B3T model predictions was below 15 % in these cases. Moreover, the unique database of containment parameters presented in this paper may provide useful for future researchers or designers dealing with the preconceptual design of PCCs.