Stress strain state of asphalt concrete pavements of steel bridges

The object of research is the stress-strain state of asphalt concrete pavements of steel bridges with an orthotropic slab under traffic load. Research is necessary because one of the main problems of steel bridge deck pavements is the formation of longitudinal cracks in asphalt concrete above the main beams of superstructures. At the same time, there are no instructions in the engineering standards to prevent the appearance of such a crack. The lack of clear instructions, in turn, is because the stress-strain state of the roadway of metal bridges has features that have not been studied sufficiently. Method. The primary research method uses a software package that implements the finite element method. During modeling, shell finite elements are used to model the metal span, and three-dimensional finite elements are used to model the protective-cohesive and asphalt concrete layers. A three-axle truck was considered as a wheel load under various loading schemes. In addition, the physical and mechanical parameters of the protective layer and asphalt concrete were evaluated at different rent temperatures, on which they largely depend. Results. As a result of modeling the superstructure section, it was found that tensile stress occurs in the upper fiber of asphalt concrete above the main beam. And the closer the wheel is to the main beam, the greater this stress can lead to future cracks. However, a phenomenon has been found that at sufficiently high temperatures, the highest tensile stresses in the top fiber of asphalt concrete occur near the wheel. In contrast, the highest tensile stresses always occur above the main beam at sub-zero temperatures. Considering that cracks in asphalt concrete arise as a result of the gradual accumulation of damage and assuming that the traffic load moves mainly along the wheel path zone, it can be concluded that the spacing of the wheel path and walls of the main beams in space can lead to an increase in the service life of asphalt concrete pavements of metal bridges