Curling stresses and thermal eigenstresses in a concrete pavement slab

Abstract

Concrete pavements are mostly subjected to unsteady heat conduction, resulting in spatially nonlinear temperature distributions in thickness direction, and leading to thermal stresses. Thermal stresses of a concrete slab are analyzed based on in-situ temperature measurements and the evaluation method proposed in (Schmid et al. 2022). Temperature data are taken from the same field testing site as in (Schmid et al. 2022), but from a different monitoring period covering 7-days in spring. Unsteady heat conduction in vertical direction is simulated using histories of surface temperatures as boundary conditions. Their numerical values are obtained by spatial extrapolation of temperatures measured in four depths of the slab. Temperature profiles are computed and translated into thermal eigenstrains. The latter are split into three parts: eigenstretches of the slab, which are unconstrained, eigencurvatures of the slab, which are constrained by its support conditions such that curling stresses are activated, and eigendistortions of plate-generators, which are virtually prevented such that selfequilibrated eigenstresses are activated. The latter are evaluated analytically. Curling stresses are quantified numerically, prescribing a modulus of subgrade reaction of 100 MPa/m. Disregarding thermal eigenstresses overestimates tensile stresses in the afternoon, at the bottom of the slab, in its central region, by 14 %. Disregarding thermal eigenstresses underestimates tensile stresses in the morning, at the top of the slab, in its corner regions, by 59 %.