Study on the Formula of the Concrete Fatigue in Cement Concrete Pavement Design

Abstract: The design standards of the cement concrete pavement are that the vehicle fatigue stress and the temperature fatigue stress are less or equal to the maximum fatigue strength of the concrete. There are some incorrect mechanical concepts on the maximum stress and the fatigue stress in the design fatigue formula of in the specifications of cement concrete pavement design for highway (JTG-D40-2002). The formula have some inconsistencies, for example, the vehicle load and the temperature load are inconsistent, the mechanical concepts on the maximum stress and the fatigue stress are incorrect, and the fatigue coefficients are incorrect. Through mechanical and comparative research on the design indexes and the fatigue coefficients in the formula, the formula has been modified, and the paper has put forward the modified formula based on several important concrete fatigue formula in China, i.e. (,). Meanwhile, the comparative design has been finished between the specification formula and the modified formula, and it is concluded that the thickness of the concrete slab by current design is relatively small, explaining the occurrence of concrete slab cracking.