In three-layer reinforced concrete structures, the inner and outer layers of concrete of different physical and mechanical characteristics have different coefficients of thermal conductivity and linear temperature deformation. During the operation of buildings and structures, due to the temperature difference in the thickness of the structure along the contact planes of the layers, shear stresses may occur, which leads to bending of the structure, an increase in its deflections and a decrease in crack resistance. In this regard, when designing and calculating such structures, it is necessary to take into account the operational stresses and deflections caused by the temperature difference in the thickness of the enclosing structure.
Taking into account the fact that the cross-section of three-layer enclosing structures with a monolithic connection of layers includes various types of concrete and reinforcement, differing in the values of the initial modulus of elasticity, to solve the problem, the cross-section of the enclosing structure is reduced to a homogeneous one corresponding to the largest initial modulus of elasticity of the concrete of the outer layers.
Studies have been carried out to identify the effect of the thickness of the enclosing structure on the change in deflection, depending on the temperature difference, and its share in the total deflection of the structure. Despite the fact that the calculation results revealed a slight increase in the total deflection, taking into account the proportion of deflection that depends on the temperature difference, the study allows us to increase the accuracy of the calculation. The tendency to reduce the material consumption of structures and, consequently, a decrease in the thickness of the structure can lead to an increase in the proportion of deflection, depending on the temperature difference, which must be taken into account when choosing design solutions.