Prediction model of long-term prestress loss interaction for prestressed concrete containment vessels

Conventional methods disregard the interaction effects between concrete creep and tendon relaxation to evaluate the long-term prestressed losses. The main contribution of this paper is to present a new method to compute this interaction for prestressed concrete containment vessels. A time-dependent numerical study is conducted to compare long-term prestress losses in different prediction models. A prestress loss test program is conducted to validate the numerical analysis method for a concrete containment vessel. To perform a more comprehensive numerical study, various variables such as radius to water height ratios (R/H), tendon material (improved or normal relaxation), and different constant temperature conditions are considered in the analysis models. The obtained analytical results are categorized into three classes: creep and shrinkage losses, stress relaxation losses and simultaneous long-term losses. The analytical results show that the (R/H) ratios have no significant effects on long-term prestress loss. Nevertheless, the other investigated variables have impressive effects on the long-term loss evaluation. The analytical results are used to calculate the interaction coefficients, which demonstrate the interaction between concrete creep losses and tendon relaxation. Eventually, the interaction coefficient data are expressed as a function of stress relaxation loss to creep and shrinkage loss ratio.