The Shrinkage Model in the Non-Linear Fem Program Parma for the Design of Reinforced Concrete Pavements

The design of reinforced concrete pavements presents complex problems of modelling, owing to the marked nonlinearity of structural response of the reinforced concrete, of the foundation and the unilateral behaviour of the interaction between pavement and foundation. The external actions to which a road pavement is subjected are the result of the random superposition of a number of factors such as traffic loads and climatic effects. This paper shows the non linear model adopted from the authors for the development of the code PA.R.M.A. for the design of the reinforced concrete pavement. This model is based on the use of layered finite elements whose adoption makes possible the division of the element in ideal layers of concrete and steel. At each layer it could be assigned mechanic properties which vary with the evolution of the strain state. The shrinkage phenomenon is carried out according to the model proposed in the CEB-FIP Model Code 1990 and the contact problem between reinforced concrete plate and foundation is solved by an unilateral elasticplastic Winkler type model described by a non-linear curve which is function of geomechanical properties.