Modeling of heat transfer processes in concreting of massive reinforced concrete structures

Abstract

Massive reinforced concrete structures – foundations, walls, floors, crossbars, bridge support bodies, dams – are subject to significant temperature deformations due to concrete exothermy and external thermal effects. Uneven temperature distribution over the structure leads to the occurrence of temperature stresses, which can cause cracking in concrete and lead to a decrease in the durability of the structure. Thermophysical modeling makes it possible to predict with a high degree of probability the temperature fields of structures under construction and stresses at the design stage, optimizing concreting technologies (the rate of turnover of the formwork, heat treatment, the composition of the concrete mixture, etc.).

 The methodological basis of the research consists of the theory of unsteady nonlinear heat and mass transfer, approaches of mechanics of deformable solids, which allow modeling the stress-strain state of massive structures, taking into account the associated thermal, phase and chemical processes. When concrete hardens, an exothermic reaction of cement hydration occurs, accompanied by the release of heat. In massive structures, due to the low thermal conductivity of concrete, heat accumulates, which leads to: uneven heating; temperature deformations (expansion during heating and compression during cooling); stress due to limited freedom of deformation. Modeling of heat transfer processes makes it possible to predict temperature fields and stresses, optimize concreting technologies, and prevent structural failure. Modern computational methods ensure high accuracy of calculations, which is especially important for critical structures (dams, bridges, foundations of nuclear power plants).