Axisymmetric Finite Element Modeling of Block Pavement Subjected to Repeated Loading

A two-dimensional finite element code, PAVE2D, is used to model a concrete block pavement as a solid of revolution. However, use of this approach in its normal form poses a difficulty-the relatively stiff elements near the axis of revolution cannot rotate. It is proposed that the stiffness of these elements be modified to allow some degree of rotation that would still give a reasonable state of stress. This is done by determining a ratio of the modulus of a flat circular plate and that of a straight beam of equal span and thickness that would give an equal rotation along the entire span. This ratio is used to reduce the modulus of the elements representing the concrete blocks according to their proximity from the axis of revolution. PAVE2D is a large deformation capable code that has an updated Lagrangian formulation. The proposed method has an advantage over the traditional three-dimensional finite element analysis because it accommodates stress-related nonlinearity and geometric nonlinearity, and it is capable of simulating loading and unloading without huge computing resource requirements. The computer simulations shown include modeling a field test in which a 70-mm-thick block pavement was subjected to loading from a falling weight deflectometer and modeling block pavements 80 mm and 120 mm thick subjected to repeated loading. The proposed method can be used to evaluate different block shapes and arrangements and can be used to predict rutting characteristics of these pavements. The method applies to rigid pavement.