Influence of Thermal Actions on the Effectiveness of Prestressing in Cylindrical Water Tanks

Abstract

The paper presents the findings of an analysis of a tank subjected to thermal effects caused by variations in air and liquid temperatures. The structural analysis focuses on the influence that thermal actions exert on the distribution of prestressing force. One of the important aspects addressed is the application of transient heat transfer analysis instead of the steady-state approach, allowing for a more accurate yet realistic representation of thermal effects within load combinations used to evaluate prestressing force. The study suggests that thermal actions should reflect the average annual temperatures of air and liquid separately, considering the transient thermal field. This hypothesis contradicts the standard approach. Numerical simulations using the finite element method were conducted in order to model transient heat transfer (CFD model) and the structural response of the tank (with axisymmetric shell model). The results indicated that temperature gradients across the tank wall may be linear or non-linear, varying with time and the amplitude of air temperature. Consequently, a modified formula for the reduced temperature gradient is proposed. The research emphasises the importance of incorporating transient thermal effects and the temperature-influenced distribution of prestressing force, which may have a significant impact on the safety of prestressed tanks.