|Title:||Evaluation of asphalt concrete pavement service life using 3D nonlinear finite element analysis and nonlinear fatigue damage model|
|Subject:||Pavements, Asphalt concrete -- Testing.|
Finite element method.
Hong Kong Polytechnic University -- Dissertations
|Department:||Department of Civil and Structural Engineering|
|Pages:||xiii, 212 leaves : ill. ; 30 cm.|
|Abstract:||Asphalt concrete mixture is the most commonly used material in pavement construction because of its high-quality engineering performance such as elasticity, stability, durability and water resistance. Determination of service life is one of the most important aspects in the design of asphalt concrete pavements. The design life of an asphalt concrete pavement can be defined as the period that a pavement can be used without severe damage. In the last 50 years, many researchers tried to get accurate estimation for the life of asphalt concrete pavement to optimize the usage of natural resource and reduce premature failure of pavement. However, premature pavement failure is still common, resulting in high maintenance cost and unsafe service condition. Fatigue cracking is the most important structural distress used in the design of a pavement and the models used for this design require significant improvement. The conventional fatigue design models are commonly used to analyze pavement structures. These types of models assume linear elastic material properties and static loading conditions. In reality, pavement materials are not linear elastic materials. For example, asphalt concrete mixtures are viscoelastic materials and material performance deteriorates with continuous damage accumulation. Furthermore, the traffic loads are dynamic. The difference between the conventional fatigue design assumptions and the actual pavement conditions leads to significant differences between measured and predicted pavement responses.|
A study has been conducted at Hong Kong Polytechnic University to develop a procedure to better predict long-term performance of asphalt concrete pavements. To achieve this end, complicated finite element techniques are employed and parametric studies are performed. The fatigue destructive mechanics (fracture mechanics and damage mechanics) are used to develop a 3D Finite element model that can be applied to characterize the nonlinear properties of the asphalt concrete materials. A set of materials tests is preformed to evaluate various bituminous wearing course materials by using Universal Servo Pneumatic Testing System in Hong Kong Road Research Laboratory such as indirect tensile modulus, dynamic creep, indirect tensile fatigue and wheel tracking. The materials for this study comprise conventional asphalt concrete wearing course (ACWC) and stone mastic asphalt (SMA) with a virgin 60/70 bitumen and different modified bitumen (Polypropylene, Crumb rubber, Cellulose fiber, Asbestos fiber and Gilsonite). The test results are analyzed in a multiple regression technique to capture the parameters in the proposed creep model. With the developed materials models, the typical flexible pavement structures are modeled in the finite element software, ANSYS. The real vehicle loads are employed and the effects of the footprint shape, loading frequency, and curing time are studied by using this computer simulation technique. The simulation results show that the SMA has a better healing effect and a longer micro-damage fatigue life than other mixtures with significantly enhanced healing effect. In addition, after the fatigue analysis and the prediction of the service life of flexible pavement, a sensitivity analysis is conducted to investigate the effect of cross section and load attributes factors on pavement response.
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