Dyanamic Analysis of FWD Loading and Pavement Responce Using a Three Dimensional Dynamic Finite Element Program

Abstract

Multi-layer analyses are commonly used to analyze falling weight deflactometer (FWD) measurements and back calculate pavement layer moduli. This type of analysis assumes static loading conditions and linear elastic material properties. The FWD loading cycle cannot be considered in any sense as a static load. It is a dynamic load with a duration in the range of 30 to 40 msec. Also, paving materials and subgrades are not linear elastic materials and their response to static loads is different than that to dynamic loads, such as FWD loading. The difference between the multi-layer analysis assumptions and actual loading and material conditions is significant. In this paper a three-dimensional dynamic finite element program (3D-DFEM), ABAQUS, is used to conduct a non-linear dynamic analysis of FWD tests on a flexible pavement section. Verification studies have, been conducted of the 3D-DFEM to verify its static and dynamic analysis of both rigid and flexible pavements and no significant difference was found between the predicted pavement response using the 3D-DFEM and the field measured pavement response. A design of experiment was developed to study the effect of layer thicknesses and moduli on pavement surface deflections at various offset distances. Analysis of variance (ANOVA) and regression analysis were conducted to develop statistical models which can be used to predict pavement surface deflection at different offset distances as a function of layer thicknesses and moduli.

Dynamic Analysis of Thin Asphalt Pavements by Using Cross-Anisotropic Stress-Dependent Properties for Granular Layer

“…Mamlouk and Davis (9) concluded from elastodynamic analysis that dynamic deflections under FWD tests were greater than the corresponding static displacements at some locations because of local amplification in the layered pavement structure. Three-dimensional (3-D) finite element (FE) models have recently been used in dynamic pavement analysis (10)(11)(12)). An FE model allows consideration of more-complex material constitutive models and more realistic interface and boundary conditions than the analytical method can consider.…”

Numerical comparison of flexible pavement dynamic response under different axles

“…3D FEMs have recently been successfully used in pavement dynamic analysis (Zaghloul et al 1994, Shoukry and William 1999, Saad et al 2005,Al-Qadi et al 2008). There are various advantages in using a 3D FEM: first, 3D FEM allows consideration of complex behaviour of A. Sarkar 2 pavement material; second, simulation of different complex situations such as moving multiple loads; third, the analysis results may substitute for the laboratory or field test results and fourth, the analysis allows more realistic interface, footprint of the loaded wheel and boundary conditions than the analytical method.…”

Analytical dynamic displacement response of rigid pavements to moving concentrated and line loads

“…Under the aforementioned assumptions, relationships between displacement and moment of slab satisfy the following equations where $ 2 = o 2 /ox 2 + o 2 /oy 2 is the Laplace operator. As the most widely used foundation model in rigid pavement design, the Winkler elastic foundation model assumes that the reactive pressure is proportional to the vertical displacement of the slab, i.e., q(x, y, t) = KW(x, y, t) (Kenney, 1954;Sun, 2001a;Zaghloul et al, 1994). Here, K is the modulus of subgrade reaction and is assumed to be constant to represent linear elasticity of the subgrade.…”

“…Kenney (1954) studied the steady-state response of a moving load on a beam on elastic foundation. Finite element procedures have been developed to carry out the response of a thin plate to dynamic loads with applications in pavement design and nondestructive evaluation (Taheri, 1986;Kukreti et al, 1992;Zaghloul et al, 1994;Kim and Roesset, 1996;Sun, 2001a;Sun, 2001b). Deshun (1999) applied the variational principle to solve the vibration of thick plates.…”