Crack Element in the Non-linear f.e.m. Program PA.R.M.A. for the Design of Reinforced Concrete Pavements

The code PA.R.M.A. (PAvement Reinforced Model Analysis), developed by the research group of Parma University, is a non-linear layered f.e.m. program for P.C., oriented to the analysis of reinforced concrete slabs resting upon an elastic-plastic foundation and subjected to monotonic loadings, capable of evaluating both the serviceability load and the ultimate load. In the program, flexible slabs exposed to the activity of local heavy loads, unilateral contact constitutes the dominating feature. Unilateral bonds may also become evident in the case of eccentrically loaded thick slabs or when plastic deformations appear in the elastic-plastic foundation due to variable loads. An orthotropic incrementally linear relationship and equivalent uniaxial concept are used to represent the behaviour of concrete under biaxial stresses while a uniaxial bilinear elasto-plastic model with hardening is employed for reinforcing bars. After cracking, the orthogonal fixed crack model is adopted and tension stiffening, reduction in compressive strength and stiffness after cracking, and strain softening in compression are accounted for. In this paper, is presented the implementation of the program with an original formulation of a crack element dedicated to the study of the effect in the plate due to the presence of crack in the top of it. The proposed finite element model has been tested by the comparisons with other analytical models available in literature, showing a good agreement. For the covering abstract see ITRD E118503.