Calculation of Temperature fields and Stresses during the Construction of a tank wall for Storing Liquefied natural Gas

Abstract

Objective. Development of a method for calculating the thermal stress state in a reinforced concrete tank wall during continuous concreting in slipform, taking into account the thermophysical and mechanical characteristics, as well as the kinetics of heat generation and concrete strength gain.
Method. The study was conducted in a two-dimensional axisymmetric formulation using the finite element method. Convective heat exchange with the environment, internal heat release according to the empirical curve, temperature deformations, shrinkage, and changes in the elastic modulus and strength of concrete over time are considered. The calculations were implemented in MATLAB with sequential activation of elements during concreting.
Result. Temperature and stress distributions were obtained for two seasons (July and September). The maximum temperature difference across the wall thickness was 18–19°C. It was found that in the support zone of the rigid connection between the wall and the foundation, the hoop stresses in the elastic calculations reach 5 MPa with a concrete tensile strength of 3.2 MPa, while the z-axis stresses reach 15.4 MPa, leading to a high risk of vertical and horizontal cracks. Reducing the heat release of concrete by 40% reduces the stresses by only 22–40%, without eliminating the risk.
Conclusion. The main cause of cracking is related to the rigid connection between the wall and the foundation. To reduce the risk, it is recommended to reduce the concreting rate at the initial stage to 1 m/day. In other sections of the wall, the likelihood of cracks is negligible.