On the basis of the theory of thermoelasticity, the problem of the thermally stressed state of a two-layer fragment of a bridge structure, consisting of a metal base and an asphalt-concrete upper layer, under conditions of a change in the ambient temperature at different values of the coefficients of thermal linear expansion of the layers is considered. Using the finite element method, the fields of thermal stresses, deformations and displacements are constructed for various values of the thermomechanical characteristics of the layers. The analysis of the influence of the values of thermomechanical parameters on the stress-strain state of the system is carried out. It is shown that with an increase in the incompatibility of these characteristics, the intensities of stresses and strains increase. The zones of concentration of these functions are found. It is recommended to use materials with close values of their thermomechanical parameters when designing bridges to avoid their premature destruction.

No abstract

In the practice of road construction, one of the most common phenomena accompanied by delamination, subsequent cracking and destruction of the asphalt concrete pavement on a rigid (cement concrete or metal) base of a road or bridge is the effect of concentration of shear thermal stresses between the pavement and the base in the edge zones of the structure. They are caused by the fact that, as a rule, the coefficients of linear thermal expansion of the phases of the system have different values, which contributes to the occurrence of incompatible shrinkages and expansions in them. Under conditions of frequent temperature changes in heterogeneous asphalt concrete structures with thermomechanical incompatibility of their components, these effects can contribute to their accelerated aging. At the same time, with the thermomechanical compatibility of materials, a more favorable distribution of internal stresses of thermal and mechanical origin is achieved, which excludes premature degradation of the strength of the contacting phases and the entire system as a whole. Using the methods of strengthof materials and the finite element method, it has been established that under the conditions of a change in the temperature of the system during its seasonal and daily fluctuations, shear stresses are subjected to the highest concentration. They are localized in the edge zone of the plane of contact between the layers and increase with an increase in the thickness and modulus of elasticity of the upper layer. These stresses are the main reason for the occurrence of plastic deformations in these zones and subsequent delamination of the structure in them. It is proposed to reduce the concentration and level of generated high-gradient shear stresses by reducing the thickness of the asphalt concrete layer in these areas.

No abstract

No abstract