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Author: Benjamin Shane Underwood
Publisher:
Published: 2006
Total Pages: 127
ISBN-13:
DOWNLOAD EBOOKKeywords: Asphalt, modeling, anisotropy, viscoelastoplastic continuum damage.
Author:
Publisher:
Published: 2004
Total Pages:
ISBN-13:
DOWNLOAD EBOOKPerformance modeling of asphalt concrete pavements is one of the most difficult, but important tasks facing pavement engineers. Experiences at North Carolina State University suggest that this task is best accomplished by utilizing two separate models; one to account for the material behavior and another to account for boundary conditions, such as tire-pavement interaction, temperature gradient along the layer thickness, pavement structural design, etc. The material characterization model should focus on the material irrespective of geometry, i.e., fundamental properties. The structural model should be robust enough to account for the range of conditions experienced by pavements in service. Two peer-reviewed and published papers are presented here which deal with the development of a constitutive material model for asphalt concrete. In the first, the viscoelastoplastic continuum damage model in tension is applied to materials from the Federal Highway Administration's Accelerated Load Facility study on modified mixture performance. It is shown that the material model is capable of describing the behavior of the tested mixtures over a range of conditions from primarily viscoelastic to primarily viscoplastic. Further, the model shows sensitivity to changes in asphalt binder and the ability to predict the behavior of asphalt concrete mixtures containing polymer modified binder. The second paper presents results from an experimental study of anisotropy in asphalt concrete. Anisotropy occurs due to the preferential orientation of aggregate particles in the mixture and is found to have varying levels of significance depending on both the mode of loading and the levels of deformation applied. In the linear viscoelastic range, anisotropy is found to have little effect on the material behavior, whereas under monotonic compressive loading until failure, it is found to contribute significantly. Further, it is found that temperature and rate affect the significance of anisotropy.
Author: Pradeep Hariharakumar
Publisher:
Published: 2006
Total Pages:
ISBN-13:
DOWNLOAD EBOOKThe focus of this dissertation is on constant displacment rate experiments on asphalt concrete and on developing continuum models in a general thermo-mechanical setting which will corroborate with the experimental results. Modeling asphalt concrete and predicting its response is of great importance to the pavement industry. More than 90 percent of the US Highways uses asphalt concrete as a pavement material. Asphalt concrete exhibits nonlinear response even at small strains and the response of asphalt concrete to different types of loading is quite different. The properties of asphalt concrete are highly influenced by the type and amount of the aggregates and the asphalt used. The internal structure of asphalt concrete keeps on evolving during the loading process. This is due to the influence of different kinds of activities at the microlevel and also due to the interaction with the environment. The properties of asphalt concrete depend on its internal structure. Hence we need to take the evolution of the internal structure in modeling the response of asphalt concrete. Experiments were carried out at different confinement pressures and displacement rates on cylindrical samples of asphalt concrete. Two different aggregates were used to make the sample - limestone and granite. The samples were tested at a constant displacement rate at a given confinement pressure. The force required to maintain this constant displacement rate is measured and recorded. The frame-work has been developed using the idea of multiple natural configurations that was introduced recently to study a variety of non-linear dissipative response of materials. By specifying the forms of the stored energy and rate of dissipation function of the material, specific models were developed using this frame work. In this work both a compressible and an incompressible model were developed by choosing appropriate forms of stored energy and rate of dissipation function. Finally the veracity of the models were tested by corroborating with the experimental results. It is anticipated that the present work will aid in the development of better constitutive equations which in turn will accurately model asphalt concrete in laboratory and in field.
Author: Tung Nguyen-Xuan
Publisher: Springer Nature
Published: 2023-08-12
Total Pages: 783
ISBN-13: 981992345X
DOWNLOAD EBOOKThis book contains the proceedings of the 4th International Conference on Sustainability in Civil Engineering, ICSCE 2022, held on November 25–27, 2022, in Hanoi, Vietnam. It presents the expertise of scientists and engineers in academia and industry in the field of bridge and highway engineering, construction materials, environmental engineering, engineering in Industry 4.0, geotechnical engineering, structural damage detection and health monitoring, structural engineering, geographic information system engineering, traffic, transportation and logistics engineering, and water resources, estuary, and coastal engineering.
Author: Parag Ravindran
Publisher:
Published: 2010
Total Pages:
ISBN-13:
DOWNLOAD EBOOKAsphalt bound mixtures have been put to diverse uses. The complicated nature of the material and the demanding conditions under which it is used preclude complete solutions to questions on load bearing capability under field conditions. In proportion to the quantity of its usage and in acknowledgment of modeling complexity, the material has been interrogated by many researchers using a variety of mechanical tests, and a plethora of linear viscoelastic models have been developed. Most models are intended to account for specific classes of problems. This work addresses the conspicuous absence of systematic documentation of normal forces generated as a result of shear. The normal force generated during simple shear is a clear indication of the nonlinear nature of the material. The effect of fillers (hydrated lime and limestone), air voids, aggregate gradation, asphalt source and step loading on normal force generation during torsion is experimentally investigated. Based on experimental evidence, a non-linear thermomechanical model for sand-asphalt mixtures based on the idea of multiple natural configurations is developed. The model accounts for the fact that the mixture has a natural configuration (stressfree configuration) which evolves as it is subjected to loads. Assumptions are made regarding the manner in which the material stores and dissipates energy. A key assumption is that among the various constitutive relations possible, the one that is chosen is the one that maximizes the rate of entropy production. The model that is developed accounts for the anisotropic nature of the response. The experimental results show that asphalt bound mixtures generate significant normal forces even at low rotation rates. The source of asphalt, aggregate gradation, fillers and air voids have a pronounced effect on normal stress generation. The model is corroborated against data from torsion experiments.
Author: Hyun-Jong Lee
Publisher:
Published: 1996
Total Pages: 454
ISBN-13:
DOWNLOAD EBOOKAuthor: Xueyan Liu
Publisher: Mdpi AG
Published: 2023-10-17
Total Pages: 0
ISBN-13: 9783036584744
DOWNLOAD EBOOKPavement materials such as asphalt mixtures, granular aggregates, and soils exhibit complex material properties and engineering performance under external loading and environmental conditions. For instance, the asphalt mixture shows highly nonlinear viscoelastic and viscoplastic properties at high temperatures, and it presents fatigue cracking damage and fracture properties at intermediate or low temperatures. Constitutive models based on mechanics theories have been the kernel of performance prediction of pavement infrastructures and materials. They lay down a solid foundation for material selection, design, pavement structural evaluation and maintenance decisions. Advances in mechanics modeling and associated experimental testing for pavement infrastructures and construction materials are emerging constantly, such as nonlinear viscoelasticity, viscoplasticity, fracture, and damage mechanics models. Meanwhile, various numerical modeling technologies are being developed and implemented to solve the multiscale and multiphysical equations. Examples include finite element, discrete element, and micromechanics or molecular dynamics simulations at different dimensions and scales. This reprint provides a unique platform, presenting novel studies and new discoveries in the areas of mechanics, numerical modeling and experimental testing of pavement infrastructures and materials.
Author: Andreas Loizos
Publisher: CRC Press
Published: 2017-07-20
Total Pages: 364
ISBN-13: 1351585797
DOWNLOAD EBOOKBearing Capacity of Roads, Railways and Airfields includes the contributions to the 10th International Conference on the Bearing Capacity of Roads, Railways and Airfields (BCRRA 2017, 28-30 June 2017, Athens, Greece). The papers cover aspects related to materials, laboratory testing, design, construction, maintenance and management systems of transport infrastructure, and focus on roads, railways and airfields. Additional aspects that concern new materials and characterization, alternative rehabilitation techniques, technological advances as well as pavement and railway track substructure sustainability are included. The contributions discuss new concepts and innovative solutions, and are concentrated but not limited on the following topics: · Unbound aggregate materials and soil properties · Bound materials characteritics, mechanical properties and testing · Effect of traffic loading · In-situ measurements techniques and monitoring · Structural evaluation · Pavement serviceability condition · Rehabilitation and maintenance issues · Geophysical assessment · Stabilization and reinforcement · Performance modeling · Environmental challenges · Life cycle assessment and sustainability Bearing Capacity of Roads, Railways and Airfields is essential reading for academics and professionals involved or interested in transport infrastructure systems, in particular roads, railways and airfields.
Author: Vittorio Guglielmetti
Publisher: CRC Press
Published: 2016-04-15
Total Pages: 1336
ISBN-13: 0415558549
DOWNLOAD EBOOKThe design and construction of “long and deep” tunnels, i.e. tunnels under mountains, characterised by either considerable length and/or overburden, represent a considerable challenge. The scope of this book is not to instruct how to design and construct such tunnels but to share a method to identify the potential hazards related to the process of designing and constructing long and deep tunnels, to produce a relevant comprehensive analysis and listing, to quantify the probability and consequences, and to design proper mitigation measures and countermeasures. The design, developed using probabilistic methods, is verified during execution by means of the so called Plan for Advance of the Tunnel (PAT) method, which allows adapting the design and control parameters of the future stretches of the tunnel to the results of the stretches already finished, using the monitoring data base. Numerous criteria are given to identify the key parameters, necessary for the PAT procedure. Best practices of excavation management with the help of real time monitoring and control are also provided. Furthermore cost and time evaluation systems are analysed. Finally, contractual aspects related to construction by contract are investigated, for best development and application of models more appropriate for tunnelling-construction contracts. The work will be of interest to practising engineers, designers, consultants and students in mining, underground, tunnelling, transportation and construction engineering, as well as to foundation and geological engineers, urban planners/developers and architects.
Author:
Publisher:
Published: 1948
Total Pages: 400
ISBN-13:
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