No description available.

No description available.

Asphalt pavement rutting is one of the most commonly observed pavement distresses and is a major safety concern to transportation agencies. Millions of dollars are reportedly spent annually to repair rutted asphalt pavements. Research into improvements of hot-mix asphalt materials, mix designs and methods of pavement evaluation and design, including laboratory and field testing, can provide extended pavement life and significant cost savings in pavement maintenance and rehabilitation. This research describes a method of predicting the behaviour of various asphalt mixes and linking these behaviours to an accelerated performance testing tool and pavement in-situ performance. The elastic, plastic, viscoelastic and viscoplastic components of asphalt mix deformation are also examined for their relevance to asphalt rutting prediction. The finite element method (FEM) allows for analysis of nonlinear viscoplastic behaviour of asphalt mixes. This research determines the critical characteristics of asphalt mixes which control rutting potential and investigates the methods of laboratory testing which can be used to determine these characteristics. The Hamburg Wheel Rut Tester (HWRT) is used in this research for asphalt laboratory accelerated rutting resistance testing and for calibration of material parameters developed in triaxial repeated load creep and creep recovery testing. The rutting resistance criteria used in the HWRT are developed for various traffic loading levels. The results and mix ranking associated with the laboratory testing are compared with the results and mix ranking associated with FEM modeling and new mechanistic-empirical method of pavement design analyses. A good relationship is observed between laboratory measured and analytically predicted performance of asphalt mixes. The result of this research is a practical framework for developing material parameters in laboratory testing which can be used in FEM modeling of accelerated performance testing and pavement in-situ performance.

A pre-damage method was developed to determine whether rubber particle cavitation is responsible for craze initiation, or vice versa. Tensile tests were carried out on pre-strained high impact polystyrene (HIPS) specimens which had been annealed above 100 °C to heal any crazes formed in the PS matrix during pre-straining. Moderate prestraining followed by annealing was found to reduce the yield stress of the HIPS, but not the post-yield flow stress. These observations are related to cavitation for the rubber particles, which results in a fibrillar structure within the rubber membranes of a typical "Salami' particle. The reduction in yield stress provides evidence for primary chain scission in the rubber phase during yielding: on subsequent loading of the annealed tensile bar, the rubber particle exhibits a reduced resistance to cavitation because less energy is required to form a void. It was found in the follow-up pre-straining tests on HIPS blends and at different testing temperatures that the critical pre-strain is a function of rubber content and temperature. Comparable effects are seen in creep tests. Small levels of pre-straining have little effect if the specimen is not annealed before reloading. The TEM work also confirms rubber particle cavitation as a rate-determining step in the deformation of HIPS and supports the view that cavitation precedes crazing. A modified cavitation model is proposed to account for the deformation of a cavitated particle under tension. The predictions of this model agree with the experiments that the resistance of the particle is weakened by cavitation and crazes could initiate at the lower tension. The technique of pre-straining and annealing specimens, before submitting them to conventional tensile tests, provides valuable insight into the mechanisms and kinetics of toughening.

Recent development of additive manufacturing technologies has led to lack of information on the base materials being used. A need arises to know the mechanical behaviors of these base materials so that it can be linked with macroscopic mechanical behaviors of 3D network structures manufactured from the 3D printer. The main objectives of my research are to characterize properties of a material for an additive manufacturing method (commonly referred to as 3D printing). Also, to model viscoelastic properties of Procast material that is obtained from 3D printer. For this purpose, a 3D CAD model is made using ProE and 3D printed using Projet HD3500. Series of uniaxial tensile tests, creep tests, and dynamic mechanical analysis are carried out to obtained viscoelastic behavior of Procast. Test data is fitted using various linear and nonlinear viscoelastic models. Validation of model is also carried out using tensile test data and frequency sweep data. Various other mechanical characterization have also been carried out in order to find density, melting temperature, glass transition temperature, and strain rate dependent elastic modulus of Procast material. It can be concluded that melting temperature of Procast material is around 337°C, the elastic modulus is around 0.7-0.8 GPa, and yield stress is around 16-19 MPa.

No description available.

Call number: LD2668 .T4 1957 D57 / Master of Science

Series of full-scale tests were conducted on polyurethane foam-core Structural Insulated Panels (PUR SIPs) to study the load response and creep behavior of such panels. The load response of PUR SIPs was compared with conventional stud wall panels. The effects of de-bonding between the foam-core and the OSB face-sheets were also studied to understand the effects of such change on the overall performance of PUR SIPs. At last, computer modelling was employed to simulate and predict the behavior of PUR SIPs in different loading orientations and dis-bond ratios. It was found that PUR SIPs can outperform conventional stud-wall panels in every aspect. In the case of 165 mm (6.5 in.) thick PUR SIPs, 33% dis-bond between the PUR foam-core and the OSB face-sheets caused an average of 64% reduction in ‘axial load’ capacity, an average of 75.8% reduction in ‘transverse load’ capacity, and an average of 7.9% reduction in ‘racking load’ capacity of the panels compared to brand new fully-bonded SIPs. It was also found that 33% dis-bond in 165 mm (6.5 in.) thick PUR SIPs has minimal effect on the racking load capacity of the panels. In the case of 114 mm (4.5 in.) thick PUR SIPs, 33% dis-bond be-tween the PUR foam-core and the OSB face-sheets caused an average of 63.3% reduction in ‘axial load’ capacity, an average of 79% reduction in ‘transverse load’ capacity, and an average of 29% increase in ‘racking load’ capacity of the panels compared to brand new fully-bonded SIPs. All tested panels satisfied the code requirements for the creep deflections (span/180) and they fully rebounded to their initial estate, 90 days after removal of the simulated snow loads. It was also found that weathering has minimal effect on the bond between the face-sheets and the PUR foam. After computer simulations of fully-bonded and dis-bonded PUR SIPs in two different thicknesses, it was found that SOLIDWORKS simulation software is a useful tool to predict the load response of PUR SIPs only when fully-bonded panels are exposed to transverse load orientation regardless of the thickness of the panel. In general, available Canadian and American standards were followed in this study. Where applicable, standards were adopted from other material testing methods for testing PUR SIPs. It is believed that this independent research has addressed most frequently ex-pressed concerns regarding the use and application of structural insulated panels such as de-bonding issues and creep behavior and their relationship to durability. The hope is that is research help increase the use and application of SIPs in green, high-performance, light-frame building construction in Canada. / October 2016

Le fluage asismique des failles dans la croûte supérieure est un mécanisme de déformation crucial le long des limites des plaques tectoniques. Il contribue au bilan énergétique du cycle sismique, retardant ou déclenchant le développement des grands tremblements de terre. Un enjeu majeur est de comprendre quels sont les paramètres qui contrôlent la partition entre déformations sismiques et asismiques dans les failles actives tels que la lithologie ou les transformations sous contrainte à toutes échelles et comment cette partition évolue dans le temps. Des observations géologiques réalisées dans ce travail le long de la Faille Nord Anatolienne en Turquie, combinées à des analyses de laboratoire et des traitements d’images, permettent de donner un éclairage nouveau sur ces mécanismes de fluage. En plus, les relations entre déformation finie et transfert de matière ont été utilisées en parallèle avec des données géodésiques pour comprendre l’évolution de ces mécanismes de fluage depuis le début du déplacement de cette faille.Une corrélation claire est observée entre fluage superficiel et composition des gouges de la faille : les segments sismiques sont composés de calcaires massifs sans gouge de faille argileuse alors que les segments asismiques qui fluent comprennent des gouges argileuses résultant de la transformation progressive de roches volcaniques. Dans ces zones de fluage une schistosité espacée se développe durant le premier stade de la déformation conduisant à un litage tectonique de type foliation, au début oblique puis subparallèle à la faille, qui accommode une part de la déformation asismique par dissolution cristallisation sous contrainte. En conséquence, les minéraux solubles comme le quartz et les feldspaths sont dissous conduisant à la concentration passive des phyllosilicates dans les gouges de failles qui sont ensuite altérés par des circulations de fluides produisant des minéraux argileux à faible friction. Dans le même temps les zones endommagées autour de la gouge sont fracturées et les fractures scellées par des carbonates. Ces transformations minérales et structurales amollissent les gouges de failles et durcissent les zones endommagées conduisant à une évolution de la déformation sismique – asismique de diffuse à localisée.Des modèles qui intègrent déformation finie et transfert de matière révèlent deux échelles d’espace de la déformation qui correspondent à une alternance de deux types de bandes de cisaillement avec une schistosité soit oblique soit subparallèle à la faille. Diverses valeurs de la déformation finie ont été estimées pour calculer la proportion de déplacement asismique par rapport au déplacement total sismique et asismique de la faille (80 km). Cette proportion qui dépend de la lithologie de la zone de faille varie de 0.002% dans les zones sismiques calcaires et évolue dans le temps dans les zones asismiques des roches volcaniques de 59% pour les stades précoces à 18% pour les stages récents. / Aseismic fault creep in the upper crust is a key deformation process along tectonic plate boundaries. It contributes to the energy budget during the seismic cycle, delaying or triggering the occurrence of large earthquakes. One of the greatest challenges is to understand which parameters control the partition between seismic and aseismic deformation in active faults, such as lithology or stress-driven transformations at all scales and how this partition evolves with time. Geological observations along the North Anatolian Fault in Turkey combined with laboratory analyses and imaging techniques performed in the present study shed new light on these mechanisms of fault creep. Moreover, the relationship between finite strain and mass change was compared with geodesy data in order to understand the evolution of these creep mechanisms since the beginning of this fault displacement.A clear correlation is shown between shallow creep and near-surface fault gouge composition: seismic segments of the fault are mostly composed of massive limestone without clay gouges, whereas aseismic creeping segments comprising clay gouges result from a progressive change of volcanic rocks. Within these creeping zones, anastomosing cleavage develops during the first stage of deformation, leading to tectonic layering that forms a foliation, oblique at first and then sub-parallel to the fault. This foliation accommodates part of the aseismic creep by pressure solution. Consequently, the soluble minerals such as quartz and feldspars are dissolved, leading to the passive concentration of phyllosilicates in the gouges where alteration transformations by fluid flow produce low friction clay minerals. At the same time damage zones are fractured and fractures are sealed by carbonates. As a result, these mineralogical and structural transformations weaken the gouge and strengthen the damage zone leading to the change from diffuse to localized seismic-aseismic zones.Models integrating finite strain and mass change reveal two spatial scales of strain that correspond to the alternation of two types of shear bands, with cleavages oriented either oblique or sub-parallel to the fault zone. Various total strain values were estimated in order to calculate the aseismic part of the total 80 km displacement along the locked and creeping sections. The aseismic strain fraction of the total tectonic strain in the fault depends on the fault lithology and varies from 0.002% in seismic zones made of limestone and evolves with time in the creeping zones made of volcanic rocks from 59% in the early stages of fault development to 18% in the recent times.

No description available.