Tsybulskyi V. Improvement of the calculation method of bridges rigid pavement with composite reinforcement

A review of the failure causes studies of reinforced concrete structural bridge elements showed that the main reasons of these elements failure are steel reinforcement corrosion, loss of working volume, unsatisfactory condition of expansion joints on supports, low stability of concrete under bending loads. The main approaches to solving the identified problems according to world practice are the composite materials (FRP-reinforcement) use as a structure reinforcement, of which basalt is considered progressive. The generalization of the basic approaches to the decision of wear resistance of elements problems, methods and models of designs calculation on durability has allowed to improve a reinforced concrete constructive road bridge pavement elements calculation method which is developed on the basis of the bending theory of layered designs. During the development of the improved method, the stress-strain state of the plate as a sufficiently thin shell of large curvature, which consists of isotropic layers with different physical and mechanical characteristics, was investigated. Kirchhoff's hypotheses were introduced and the expressions of transverse stresses were obtained, which made it possible to take into account the influence of shear deformations in the calculation method. As a result of the research, the equilibrium equation in the variational way, boundary conditions and the general system of solving equations were obtained. From the systems of differential equations the deflection function along the length of the beam expression for the case of sinusoidal load is obtained. A model and algorithm for the improved calculation of cement-concrete pavement reinforced application with composite materials based on layered systems have been developed. The algorithm of the improved method application allows to practically determine normal stresses in layers of pavement and to carry out check of durability on equivalent stresses, applying criterion of Coulomb-More durability. According to the calculation results by the improved method, the deflection coefficient of reinforced concrete structural elements according to the classical theory and the refined method is obtained, which is 1.4 and confirms the feasibility of taking into account shear deformations in the girder slabs design. A practical conclusion was also made on the feasibility of reinforcing the top layer of pavement in order to ensure its strength and performance. The stresses that occur in FRP rods differ from 2.22 to 6.74 times compared to steel reinforcement, due to the characteristics of these materials. The analysis of experimental researches of girder structures plates of the bridges reinforced by FRP-rods from concentrated loading by a wheel is carried out. From a practical point of view, it is proved that the improved method allows to take into account different options for the operation of pavement, which makes it possible to provide strength during the operation of the structure.