Computer experiments on environmentally induced stresses in unreinforced concrete pavement slabs

Abstract

Synopsis The paper is concerned with the computation of deflections and stresses in an unreinforced concrete pavement slab subjected only to the effects of tempera–ture and humidity. The basis of the computer simula–tion is presented in three stages: (a)the histories of material properties and environmental variables; (b)the computation of the distributions of imposed ther–mal and shrinkage strains through the depth of the slab, using finite difference techniques; (c) the compu–tation of the lift–off of the slab and the consequent stresses, using finite element techniques. It is shown that by far the largest tensile stresses are induced ifthere is external restraint of the longitudinal movement of the slab. Stresses significant enough to threaten tensile fail–ure of the concrete can also occur (in the absence of restraint) as a result of the early effects associated with the heat of hydration of the cement, and under the influence of the long–term shrinkage. Computer exper–iments are reported in which the injhences of a number of variables are examined, including those for slab dimensions, climatic changes and the curing of the concrete.