Visit to Uganda of Her Royal Highness Princess Margaret, Countess of Snowdon and the Earl of Snowdon PDF Download
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Author:
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ISBN:
Category : Uganda
Languages : en
Pages : 20
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Author:
Publisher:
ISBN:
Category : Uganda
Languages : en
Pages : 20
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Category :
Languages : en
Pages :
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This research documents the findings from the study of failure mechanisms of fatigue cracking in asphalt pavements using the finite element program that employs the viscoelastic continuum damage model for asphalt layer and a nonlinear elastic model for unbound layers. Both bottom-up and top-down cracks are investigated by taking several important variables into account, such as asphalt layer thickness, layer stiffnesses, pressure distribution under loading, and load levels applied on the pavement surface. The crack initiations in different pavement structures under different loading conditions are studied by monitoring a damage contour. The developed finite element code, called VECD-FEP++, employs the viscoelastic continuum damage model as the constitutive model of asphalt concrete and the universal model (or so-called Uzan-Witczak resilient modulus model) for unbound materials. The finite element analysis of various pavement-load combinations showed significantly different failure mechanisms. Details on the VECD-FEP++ and the findings are given in the following chapters.
Author: Alireza Asgari
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ISBN:
Category : Finite element method
Languages : en
Pages : 222
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Author: Ming-Shan Yeh
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ISBN:
Category : Finite element method
Languages : en
Pages : 466
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Author: Zhi Suo
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ISBN:
Category : Finite element method
Languages : en
Pages : 424
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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.
Author: John Crawford
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ISBN:
Category :
Languages : en
Pages : 87
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An evaluation and derivation of the nonlinear version of the Airfield Pavement (AFPAV) code which is based on the finite-element structural analysis technique is presented. This code provides an analytical capability for modeling all types of pavement systems and could be used in conjunction with the rational pavement evaluation procedure being developed by the Air Force Weapons Laboratory (AFWL). Professor Hardin's nonlinear stress/strain relationships for base and subgrade materials are used in this code to simulate nonlinear behavior by a series of piecewise linear analyses of the pavement structure. The improved analytical predictions effected by using the nonlinear version of the code are demonstrated by comparing the results with the data from full-scale pavement test sections.
Author:
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ISBN:
Category : Dissertations, Academic
Languages : en
Pages : 868
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Author: B. Vuong
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Category : Pavements
Languages : en
Pages : 34
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Category :
Languages : en
Pages :
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Author: Cesar Tirado
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ISBN:
Category : Pavements
Languages : en
Pages :
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