Analysis On Thermal Stability Of Concrete Pavement

In this paper, based on the thin plate theory of a small deflection, we discussed the thermal stress stability of concrete pavement in the engineering. We considered two kinds of boundary conditions (BC) as the style of connection at the contraction joints, one is called a fixed-hinged and the other is rotating flexible hinge. However, compared with the critical temperature variation, we can ignore the temperature variation along the thickness direction. So we didn't consider the impact of the temperature field along the thickness direction of the bending plate. As a result, we considered the problem of the thermal stress stability as the stability under the equivalent thermal pressure. We chose the Poisson ratio and the parameterβwhich characterized the form of elastic supports in the BC as the perturbation arguments, and obtained perturbation solutions of the permissible critical temperature variations and the deflections of the concrete pavement in two kinds of boundary conditions. We get a approximate solution by means of the Least Square Method when the Non-homogeneous boundary conditions of the perturbation equations occured.Numerical results show that: the perturbation solutions of the deflection of the concrete pavement plate present symmetry about the center section on the plate along the width direction, the second order perturbation solution of the deflection must be concerned; critical temperature variation increases with the thickness, but do a little change with the Poisson ratio, and aspect ratioλ; the ratio of the perturbation solution of second-order and the zero-order of the critical temperature variation has a linear increments with the parameterβ. Comparison with the theory of Euler struts, we obtain that the value of the critical temperature variation of is equal to the perturbation solution of zero-order which derived from the plate theory and it is less than the value of the plate theory, this means that the critical variable temperature of using Euler's theory as a design method is inclined to safety, so Euler's theory can be applied as a guidance in the pavement design. We also have a brief compare the perturbation solution of the critical heat stress with the finite element solution, it shows that, the error between the perturbation solution of the critical heat stress and the finite element solution reduced whenλincreases; as the fixed-hinged concrete pavement, whenλis less than 0.25, the error between the two is greater than 3%; whenλis larger than 1, the error is less than 1% and tends to 0 gradually asλincreases, this result implies that the solution abtained from Ansys can only be used whenλis higther than 0.25.