Abstract: The use of self-consolidating concrete (SCC) in the concrete industry in cast-in-place applications, including repair applications, is growing given the various advantages offered in both fresh and hardened states. The present study deals with the design and performance of fiber-reinforced self-consolidating concrete (FR-SCC) as a repair material of concrete infrastructure. The study also considers the use of various steel and synthetic fibers (five fibers in total) that were used to produce FR-SCC and fiber-reinforced self-consolidating mortar (FR-SCM) that can be employed for structural and non-structural repair applications. The study evaluates the effect of material properties and mixture composition of the fibrous concrete and mortar on workability, mechanical, visco-elastic, durability, and structural behavior. The investigation that is presented in this thesis included the testing of 28 full-scale beams under four-point flexural loading. The majority of these beams were repaired by casting concrete to fill a relatively thin section along the tension zone of the beams. The repair technique was based on the FR-SCC characteristics including the maximum fiber volume and length. This technique required mixtures of high range of fluidity. The optimized FR-SCC and FR-SCM mixtures exhibited excellent flow characteristics along the 3.2-m long beams without blockage, segregation, nor debonding at the interface of repair-substrate concrete. Based on the structural characteristics of the composite beams, the overall performance of the beams repaired using the FR-SCC and FR-SCM was similar or higher (up to 2.6 times) than that of monolithic beams made with conventional vibrated concrete (CVC). The use of optimized FRSCC mixtures enabled the replacement of 50% of the tension steel reinforcement in repair sections; i.e., the number of bars in the tension zone decreased from three bars to two bars with the addition of fibers in the SCC without mitigating structural performance. The degree of prediction of crack width, cracking load/moment, ultimate loads, and deflection of various FR-SCC and FR-SCM mixture was evaluated using several design and code models. The results indicate that these code models can provide safe predictions for crack and ultimate loads, as well as crack width of FR-SCC. The deflection of FR-SCC is unsafe but predictable by these code models. In total, 18 large-scale beams were tested in four-point for flexural creep. FR-SCC incorporating steel fibers combined with expansive agent provided overall performance up to 10 times of that obtained with CVC with the same fiber type and volume. The cracking under constant load was reduced by 60% to 80% using self-consolidating fibrous mixtures made with or without expansion agents, compared to SCC without fibers. The best combination to reduce the cracking potential when the restrained shrinkage ring test was employed was obtained with SCC mixtures made with steel fibers and expansive agent. Models were elaborated to predict the time-to-cracking for FR-SCC and FR-SCM mixtures based on mixture modulus of elasticity and drying and autogenous shrinkages. The project involved extensive testing of highly flowable fibrous materials to determine drying shrinkage (nearly 260 prisms), modulus of rupture (nearly 180 prisms), as well as compressive and splitting tensile strengths and elastic modulus (nearly 2100 cylinders). Based on the results, models were proposed to predict these key material properties that affect the performance of FR-SCC and FR-SCM used in repair applications. In addition to FR-SCC, the investigation also was set to evaluate the feasibility of using fiber-reinforced superworkable concrete (FR-SWC) in construction and repair applications. Such highly flowable concrete that requires limited vibration consolidation can represent some advantages over FR-SCC (lower admixtures demand, lower risk of segregation, greater robustness, lower formwork pressure, etc.). The energy needed to ensure proper consolidation, using either vibration or rodding, applied on samples made with FR-SWC was determined. The energy requirement took into consideration the development of mechanical properties, the resistance to segregation, and the development of proper surface quality. The study also demonstrated the higher overall structural performance of optimized FR-SWC compared to the corresponding FR-SCC mixtures. The findings of the thesis on the design and performance of highly workable fiber-reinforced cementitious materials should facilitate the acceptance of such novel high-performance material in infrastructure construction and repair applications. // Résumé: L'utilisation du béton autoplaçant (BAP) dans l'industrie du béton dans les applications du coulage sur place incluant les applications de la réparation, est en croissance vu les divers avantages offerts à l'état frais et à l'état durci. La présente étude traite de la conception et la performance des bétons autoplaçants fibrés (BAPF) en tant que matériau de réparation des infrastructures en béton. L'étude considère également l'usage de différentes fibres métalliques et synthétiques (cinq fibres au total) qui ont été utilisées pour produire des BAPF et des mortiers autoplaçants fibrés (MAPF) pour des applications de réparations structurales et non structurales. L'étude évalue l'effet des propriétés du matériau et la composition des bétons et mortiers fibrés sur l'ouvrabilité, les propriétés mécaniques, viscoélastiques, de durabilité et le comportement structural. L'étude présentée dans cette thèse a inclus 28 poutres à grande échelle testées sous un chargement flexionnel à quatre points. La majorité de ces poutres a été réparée par le coulage du béton pour remplir une section relativement mince tout au long de la zone tendue des poutres. La technique de réparation a été basée sur les caractéristiques des BAPF incluant le volume maximal et la longueur maximale de fibres. Cette technique a requis des mélanges de haut niveau de fluidité. Les BAPF et MAPF ont exhibé d'excellentes caractéristiques d'écoulement le long de 3,2 m, la longueur de la poutre, sans blocage, ségrégation, ni décollement à l'interface entre le béton de base et le béton de réparation. En se basant sur les caractéristiques structurales des poutres composites, la performance globale des poutres réparées en utilisant les BAPF et les MAPF était similaire ou supérieure (jusqu'à 2,6 fois) que celle des poutres monolithiques fabriquées d'un béton conventionnel vibré (BCV). L'utilisation des mélanges de BAPF optimisés a permis de remplacer 50% du ferraillage tendu dans les sections de réparation; c'est-à-dire que le nombre des barres d'armatures dans la zone tendue a réduit de trois barres à deux barres avec l'addition de fibres dans le BAP sans mitiger la performance structurale. Le degré de prédiction de la largeur de fissures, charge de fissuration, charge ultime et déflexion de différents mélanges de BAPF et MAPF a été évalué en utilisant quelques designs et modèles de codes. Les résultats ont montré que ces modèles ont pu fournir de prédictions sécuritaires pour les charges de fissuration et ultime, ainsi que la fissuration des BAPF. La déflexion des BAPF est non sécuritaire mais reste prédictible par ces modèles de codes. En total, 18 poutres à grande échelle ont été testées en fluage flexionnel de quatre points. Des BAPF contenant des fibres métalliques combinées avec un agent expansif ont fourni une performance globale jusqu'à 10 fois celle obtenue avec un BCV contenant le même type et volume de fibres. La fissuration sous une charge constante a été réduite de 60% à 80% en utilisant des mélanges autoplaçants fibrés fabriqués avec ou sans agents expansifs, par rapport au BAP sans fibres. La meilleure combinaison pour réduire le potentiel de fissuration avec l'essai du retrait restreint a été obtenue avec des mélanges de BAP contenant de fibres d'acier et un agent expansif. Des modèles ont été élaborés pour prédire le temps de fissuration des mélanges de BAPF et MAPF basés sur le module d'élasticité du mélange et les retraits de séchage et endogène. Le projet comportait de nombreux essais sur les mélanges fibrés de haute fluidité à savoir la détermination du retrait de séchage (près de 260 prismes), le module de rupture (près de 180 prismes), ainsi que la résistance en compression, la résistance en traction et le module d'élasticité (plus de 2100 cylindres). En se basant sur les résultats, des modèles ont été proposés pour prédire ces propriétés clés qui affectent la performance des BAPF et MAPF destinés aux applications de réparation. En plus des BAPF, l'étude a aussi été faite pour évaluer la faisabilité de l'utilisation des bétons semi-fluides fibrés (BSFF) dans les applications de construction et de réparation. Tels bétons de haute fluidité requérant une consolidation limitée peuvent présenter certains avantages par rapport aux BAPF (plus faible demande en adjuvants, plus faible risque de ségrégation, robustesse supérieure, plus faible pression sur les coffrages, etc.). L'énergie nécessaire pour assurer une propre consolidation, en utilisant soit la vibration ou le piquage, appliquée sur des échantillons de BSFF a été déterminée. Les exigences de cette énergie considèrent le développement des propriétés mécaniques, la résistance à la ségrégation et la propre qualité de surface. L'étude a aussi démontré une performance structurale globale supérieure des BSFF optimisés par rapport aux mélanges de BAPF correspondant. Les conclusions de la thèse sur le design et la performance des matériaux cimentaires renforcés de fibres et de haute fluidité devraient faciliter l'acceptation de tels nouveaux matériaux de haute performance dans les applications de la construction et la réparation des infrastructures.

L'avancée de la technologie des PRF a suscité l'intérêt de l'introduction de nouvelles fibres, comme la fibre de basalte, qui a un potentiel d'offrir une solution efficace, lorsqu’utilisée dans les structures en béton, soit sur la résistance à la corrosion, la durabilité et la rentabilité. En outre, les codes et les guides disponibles, ne fournissent pas de recommandations pour l'utilisation de barres en PRFB puisque les recherches passées dans ce domaine sont limitées. Donc, des travaux de recherche sont nécessaires pour caractériser et comprendre le comportement des barres de PRFB dans les éléments en béton armé. En conséquence, les objectifs principaux sont d'évaluer les caractéristiques à court et long terme des barres de PRFB nouvellement développées, ainsi que d'évaluer les performances structurales de ces nouvelles barres comme renforcement interne dans les poutres et les dalles de pont et d'introduire ce nouveau renforcement dans les codes et les guides de dimensionnement. Les tests expérimentaux ont été faits en trois parties. La première partie porte sur le développement de trois nouvelles barres et tendons en PRFB pour déterminer leurs propriétés physiques et mécaniques. Les performances à long terme et de durabilité ont été réalisées en conditionnant les barres de PRFB dans une solution alcaline simulant les conditions humides dans le béton pour déterminer la compatibilité comme renforcement interne dans les éléments en béton. Par la suite, les propriétés ont été déterminées et comparées avec des spécimens non conditionnés (référence). La seconde partie a porté sur sept dalles de pont en béton armé grandeur réelle avec les bords restreints, simulant les tabliers de pont les plus utilisés en Amérique du Nord, pour évaluer la performance des dalles renforcées de PRFB et d'acier. Les dalles mesurent 3000 mm de long × 2500 mm de large × 200 mm d'épaisseur. Les dalles ont été testées jusqu'à la rupture sous une charge concentrée au centre de celles-ci simulant l'empreinte d'une roue d'un camion. Les capacités en poinçonnement sont prédites en utilisant les exigences réglementaires disponibles, et sont comparées aux résultats expérimentaux. La troisième partie de cette étude portait sur les essais de 14 poutres en béton de 3100 mm de long × 200 mm de large × 300 mm de profond pour examiner le comportement en flexion et les performances en service des barres de PRFB avec deux états de surfaces: fini sablé et crénelé. Les poutres ont été testées en flexion en quatre points avec une portée libre de 2700 mm jusqu'à la rupture. Les résultats sont introduits et discutés en terme : du comportement de la fissuration, des flèches, de la capacité en flexion et des modes de ruptures. De plus, le coefficient d'adhérence (kb) des barres de PRFB est déterminé et comparé avec les recommandations des codes et guides actuels. Les résultats sont introduits et discutés en terme : du comportement de la fissuration, des flèches, de la capacité en flexion et des modes de ruptures. De plus, le coefficient d'adhérence des barres de PRFB est déterminé et comparé avec les recommandations des codes et guides actuels. Les résultats de l'étude concluent sur la viables pour la production des barres de PRFB pour respecter les exigences des codes actuelles. Également, les résultats d'essai indiquent que les barres de PRFB ont de bonnes propriétés mécaniques et peuvent être placées dans la même catégorie que les barres de PRFV, soit grade III. De plus, le comportement des poutres et des dalles de pont renforcées de PRFB est similaire que pour un renforcement en PRFV et PRFC et les exigences réglementaires sont applicables pour les barres de PRFB. / Abstract: The advances in fiber-reinforced-polymer (FRP) technology have spurred interest in introducing new fibers, such as basalt FRP (BFRP), which has the potential to offer an efficient solution when implemented in concrete structure, such as corrosion resistant, durable and cost-effective. Furthermore, the available design codes and guides do not provide any recommendations for the use of BFRP bars since fundamental studies and relevant applications are still limited. Therefore, investigations are needed to characterize and understand the behavior of BFRP bars in concrete members. Consequently, the main objectives of this experimental investigation are to evaluate the short- and long-term characteristics of newly developed BFRP bars, as well as evaluate the structural performance of these new bars as internal reinforcement for concrete beams and bridge-deck slabs to introduce these new reinforcing bars to the design codes and guides. The experimental tests were completed through three parts. The first part was conducted on three newly developed BFRP bars and tendons to investigate their physical and mechanical properties. Durability and long-term performance were assessed by conditioning the BFRP bars in an alkaline solution simulating the moist concrete environment to determine their suitability as internal reinforcement for concrete elements. Thereafter, the properties were assessed and compared with the unconditioned (reference) values. The second part of this study was conducted on seven full-scale edge-restrained concrete bridge-deck slabs simulating actual slab-on-girder bridge-deck that is commonly used in North America to evaluate the performance of concrete bridge-deck slabs reinforced with BFRP and steel bars. The deck slabs measured 3000 mm long × 2500 mm wide × 200 mm deep. The slabs were tested up to failure under single concentrated load acting on the center of each slab simulating the footprint of sustained truck wheel load. The punching shear capacities were predicted using the available provisions, and compared with the experimental results. The third part of this study included testing of fourteen concrete beams of 3100 mm long × 200 mm wide × 300 mm deep to investigate the flexural behavior and serviceability performance of sand-coated and ribbed BFRP bars in concrete beams. The beams were tested under four-point bending over a clear span of 2700 mm until failure. The results are introduced and discussed in terms of cracking behavior, deflection, flexure capacity, and failure modes. In addition, the bond-dependent coefficient (kb) of the BFRP bars was determined and compared with the recommendations of the current FRP design codes and guides. The findings of this study concluded the feasibility of producing BFRP bars meet the requirements of the current FRP standards. Also, the test results revealed that the BFRP bars had good mechanical behavior and could be placed in the same category as grade II and grade III GFRP bars. Moreover, the behavior of the concrete bridge-deck slabs and beams reinforced with BFRP bars was quite similar to the counterparts reinforced with glass- and carbon-FRP bars and the available FRP provisions are applicable for BFRP bars. The beam test results yielded an average bond-dependent coefficient (kb) of 0.76±0.03 and 0.83±0.03 for the sand-coated and ribbed BFRP bars, respectively.

abstract: There has been a renewed interest to understand the degradation mechanism of concrete under radiation as many nuclear reactors are reaching their expiration date. Much of the information on the degradation mechanism of concrete under radiation comes from the experiments, which are carried out on very small specimens. With the advent of finite element analysis, a numerical predictive tool is desired that can predict the extent of damage in the nuclear concrete structure. A mesoscale micro-structural framework is proposed in Multiphysics Object-Oriented Simulation Environment (MOOSE) finite element framework which represents the first step in this direction. As part of the framework, a coupled creep damage algorithm was developed and implemented in MOOSE. The algorithm considers creep through rheological models, while damage evolves exponentially as a function of elastic strain and creep strain. A characteristic length is introduced in the formulation such that the energy release rate associated with each element remains the same to avoid vanishing energy dissipation with mesh refinement. A creep damage parameter quantifies the effect of creep strain on the damage that was calibrated using three-point bending experiments with varying rates of loading. The creep damage model was also validated with restrained ring shrinkage tests on cementitious materials containing compliant/stiff inclusions subjected to variable drying conditions. The simulation approach explicitly considers: (i) moisture diffusion driven differential shrinkage along the depth of the specimen (ii) viscoelastic response of aging cementitious materials (iii) isotropic damage model with Rankine′s failure initiation criterion, and (iv) random distribution of tensile strengths of individual finite elements. The model was finally validated with experimental results on neutron-irradiated concrete. The simulation approach considers: (i) coupled hygro-thermal model to predict the temperature and humidity profile inside the specimen (ii) radiation-induced volumetric expansion of aggregates (RIVE) (iii) thermal, shrinkage and creep effects based on the temperature and humidity profile and (iv) isotropic damage model with Rankine’s criterion to determine failure initiation. / Dissertation/Thesis / Doctoral Dissertation Civil, Environmental and Sustainable Engineering 2020

Low temperature cracking is an important form of asphalt pavement deterioration in cold regions. The cracks develop when thermally induced stresses exceed the fracture resistance of the asphalt pavement. In this study, by incorporating HMA fracture mechanics into thermal cracking model, a new integrated model is introduced to investigate low temperature cracking performance. To evaluate its reliability and accuracy, the predicted thermally induced stress and failure temperature are compared with the fracture stress and fracture temperature obtained from thermal stress restrained specimen test. The findings indicate that this HMA fracture mechanics-based thermal cracking model has a great potential to reliably evaluate the performance of asphalt mixtures subjected to thermally induced damage.

No description available.

"Thanks to significant worldwide research directed at understanding and predicting structural behavior at elevated temperatures, analytical methods are available to support a rational, performance-based approach to the structural design of buildings for fire conditions. To utilize these analytical methods effectively, structural engineers need guidance on reliable and appropriate approaches to dealing with a variety of factors, including the effects of fire protection measures, temperature-dependent thermal and structural properties, elastic and inelastic behavior of structural components and assemblies, and thermal and structural response of framing connections. To meet the objective of guiding the structural engineer in appropriate analytical methods and parameter values for performance-based structural fire protection, this thesis proposes a comprehensive way of thinking about the design and analysis of structures for fire conditions. This integration of structural engineering and fire protection engineering into a functional framework is defined herein as Fire-Robust Structural Engineering (FRSE). The FRSE process, which is presented as a series of flowcharts, is designed to guide the structural engineer in executing the functions involved in the design of fire-safe structures and to help identify informational needs critical to these tasks. Currently, mechanisms for identifying possible resources to fulfill fire-related informational needs are generally organized for the convenience of the fire research community. Identification of resources that provide appropriate information for fire-robust structural engineering, such as laboratory fire test results, parametric studies of analytical methods, and other sources of guidance, is often difficult because these resources are rarely organized and presented for the benefit of structural engineers. To begin to resolve this problem, this thesis has developed a prototype information management system (IMS) based on the framework of the FRSE process. The IMS addresses the critical challenge of organizing and presenting the available knowledge and data in a format that is consistent with the perspective and informational needs of the structural engineer. The prototype version of the IMS has been implemented using a Microsoft Excel® platform. In addition to guidance in utilizing specific analytical methods and choosing appropriate parameter values, the structural engineer also requires an understanding of the input requirements and accuracy of various analytical methods in order to make informed decisions regarding which methods are appropriate for use with different structural configurations. Therefore, this thesis includes a model study as an example of a resource that could aid the structural engineer in making such decisions. The model study compares various analytical methods (simplified spreadsheet applications and advanced finite element techniques) to published laboratory test data and discusses concerns that the structural engineer must keep in mind when using each method. Conclusions are drawn regarding the appropriateness of each analytical method to the analysis of a fully restrained, spray-protected steel beam. Given this type of information, the structural engineer can make decisions regarding the types of analytical methods and the level of analytical sophistication required to solve a given design problem."

Prevalence rates of many types of psychopathology are lower for men than they are for women, but the causes of these discrepancies are not known. This paper focuses on two such psychopathology groups – eating disorders and depressive disorders – and examines gender differences within a transactional theory of stress that takes into account levels of cognitive processing (an expanded transactional theory of stress). Both studies found that men are more physiologically reactive to disorder-relevant, stressful stimuli and stressful events. The study on depression also found that different cognitive processes may be depressogenic for men and women: deployment of attentional resources toward negative stimuli was associated with depression in men, while deployment of attentional resources away from positive stimuli was associated with depression in women. These findings have significant implications for choosing appropriate treatment options for men and women.

No description available.

No description available.

Prevalence rates of many types of psychopathology are lower for men than they are for women, but the causes of these discrepancies are not known. This paper focuses on two such psychopathology groups – eating disorders and depressive disorders – and examines gender differences within a transactional theory of stress that takes into account levels of cognitive processing (an expanded transactional theory of stress). Both studies found that men are more physiologically reactive to disorder-relevant, stressful stimuli and stressful events. The study on depression also found that different cognitive processes may be depressogenic for men and women: deployment of attentional resources toward negative stimuli was associated with depression in men, while deployment of attentional resources away from positive stimuli was associated with depression in women. These findings have significant implications for choosing appropriate treatment options for men and women.