In the structural design of continuously reinforced concrete pavement (CRCP), thermal stresses should be properly taken into account. Thermal strains and temperatures in concrete slabs were measured on test sections of CRCP. Measured strains were divided into axial, curling, and nonlinear components, and each component was examined. It was found that the curling component is predominant in terms of transverse stress, which is important in the structural design. However, the maximum thermal stress is reduced by 25 percent because of the nonlinear component. On the basis of the results, a procedure for estimating the thermal stress in CRCP was proposed.
A method to predict thermal stress of a concrete slab was developed in this study. In this method, temperatures and thermal stresses in a concrete slab are predicted by solving a one-dimensional heat transfer equation with the control volume method and three-dimensional finite element method (3DFEM). Predicted temperatures were compared with those measured in various regions in Japan to validate the method. The thermal strains calculated with 3DFEM were also compared with those measured in test concrete pavement slabs to confirm the method’s validity. The relative frequencies of thermal stress for one year were obtained from the calculated stresses. In thin slabs (20 and 23 cm), tensile thermal stress at the bottom was greater than those estimated with the current thermal stress equation, which considers internal stress due to the nonlinearity of the temperature profile in the slab. In thick slabs (25 and 30 cm), by contrast, the current thermal stress equation gave almost the same thermal stress as the finite element method did, although the peak time for the maximum tensile stress was delayed in the thick slabs. The proposed method can be applied to a variety of concrete pavement structures under various temperature conditions.
This paper describes a structral design method developed for composite pavement which consists of a continuously reinforced concrete slab (CRCS) and a asphalt surface layer. The design method is based on the fatigue analysis of CRCS. In the analysis, loading and thermal stresses in CRCS are calculated by plate FEM model. Two effects of asphalt layer are considered in the design. One is a mechanical effect which reduces the load stress in CRCS. The other is a thermal effect which reduce the temperature differential in CRCS. The former is taken into account by using the concept of equivalent thickness besed on the composite plate theory. The latter is incorporeted by intorducing a reduction factor for temperature differential in CRCS. Values of paramters required in the method were obtained from field measurements. Based on the model, the effects of design parameters on the fatigue damage were also investigated.
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