Non-linear finite element analysis of jointed plain concrete pavement due to wheel load

Abstract

The behavior of a jointed plain concrete pavement (JPCP) has been investigated under single wheel load for interior loading using finite element technique to predict the critical pavement responses for nonlinear geomaterial characterization. Pavement foundation geomaterials, i.e., fine grained subgrade soils and unbound aggregates used in untreated base/subbase layers, exhibit nonlinear behavior. The idealized pavement system is analyzed using both 3D and axisymmetric (2D) finite element analysis. The developed 3D and axisymmetric models were analyzed for four combinations of material characterizations- (1) linear base and subgrade material, (2) nonlinear base and linear subgrade, (3) linear base and nonlinear subgrade, and (4) nonlinear base and nonlinear subgrade. Effects of slab thickness, base course material thickness, base course material strength, and subgrade type on the critical pavement responses were also studied. For the finite element analysis an axisymmetric and 3-D finite element model of jointed plain concrete pavement was developed using the general purpose finite element software ABAQUS. Granular base course and subgrade soil was modeled with solid elements considering its nonlinear material behaviors, and concrete slab was modeled with linear elastic material using solid elements. Eight nodded isoparametric brick element was used for 3D modeling and 4 noded linear quadrilateral element was used in axisymmetric modeling. The developed 3D FE model was successfully verified with available numerical results. 3D finite element analysis results for nonlinear material characterization predicts 12.4% higher surface deflection than linear elastic characterization. But the maximum tensile stress and vertical compressive stress on top of subgrade for both nonlinear and linear analysis were found to be negligible. 2D axisymmetric FE analysis was carried out and the results were compared with those predicted by 3D FE analysis. The axisymmetric finite element analysis results conforms closely with the 3D FE analysis results for vertical surface deflection and compressive stress on subgrade with a variation of 1.3% and 2.4% respectively. But the maximum tensile stress predicted by axisymmetric FE analysis at the bottom of the concrete slab is about 14% grater than the 3D FE analysis result. Nonlinear characterization of the base course material has no significant effect on the pavement responses as the stresses developed in the base course material layer is within the elastic limit. Nonlinear characterization of subgrade soil has considerable effect on the deflection of the top surface. The parametric study shows that for a jointed plain concrete pavement, the maximum values of pavement deflection, tensile stress and subgrade pressure are reduced significantly up to a thickness of 225 mm (9 inch) above which the influence of slab thickness on pavement responses reduces. The effects of base course material thickness and strength properties on the maximum values of pavement deflection, tensile stress and subgrade pressure are less significant compared to effects of slab thickness. The subgrade type has similar but significant effects on the pavement responses due to wheel load.