The Lagrangian Block Method (LBM) developed in this thesis is a simulation method. Flow properties are transported in the direction of the velocity following a Lagrangian procedure. The computational elements of the LBM are systems of blocks. These blocks are utilized in the method as containers for the storage of the flow properties (masses). During the computation, the masses in the blocks remain positive, and the total mass in the system is conserved. The resolution of the method is accurate to within one to two computational blocks. The LBM is also unconditionally stable. Accurate results can be obtained with the method using a value of the Courant number very close to unity. To demonstrate the general applicability of the LBM, simulations of advection-dominant flows using the Large Eddy Simulation (LES) turbulence model and diffusion-dominant flows using the K-epsilon turbulence model were conducted. / The LES of turbulent flows were conducted using two levels of implementation of the LBM. In full implementation of the method, both velocity and concentration are calculated using the LBM. In the partial implementation of the method, only the concentration is calculated by the LBM whereas the velocity field is calculated using a conventional Central-Differencing Scheme (CDS). Compared with the LBM, the requirement for the sub-grid scale viscosity in the velocity simulation using the CDS was significantly lower. / Simulations of turbulent flows using K-epsilon turbulence model were conducted using the same two levels of implementations. Numerical results obtained from the simulations using the CDS were more oscillatory, and they converged to the asymptotic solutions at a slower rate than those obtained from the simulations using the LBM. The results from both the K-epsilon model simulation and the LES suggest that the LBM advects and diffuses the flow properties more accurately than by the conventional CDS. The LBM is also approximately three times faster than the CDS. / LBM is mass conserving, non-negative, unconditionally stable, and relatively free of numerical oscillations. These outstanding attributes of the method have contributed to the success of the turbulent flow simulations. (Abstract shortened by UMI.)

This thesis presents a new hypoelasticity model which was implemented in nonlinear finite formulation to analyze normal and high strength reinforced concrete structures under both monotonically increasing and reversed cyclic loadings. The model includes a new hypoelasticity constitutive relationship utilizing the rotations of material axis through subsequent iterations, employment of both fixed and rotating crack models, compressive strength degradation in post-cracking regime, new uniaxial stress-strain relationships for concrete under monotonically increasing and reversed cyclic loadings, accounting for mesh sensitivity, and utilizing the tensile strength degradation due to extensive internal microcracking of the concrete. The model can account for high nonlinearity of the stress-strain behaviour of concrete in the pre-peak regime, the softening behaviour of concrete in the post-peak regime, the stiffness degradation caused by the extension of microcracks during subsequent unloadings and reloadings and the irrecoverable volume dilatation at high levels of compressive load. / The effect of element size on different behavioural aspects of reinforced concrete elements including the load-displacement and load-strain characteristics, crack pattern and ultimate load are discussed along with a comparison with the experimental data where available. Various analyses indicated that the length of the descending branch of the tensile stress-strain curve of concrete defined by the value of the ultimate tensile strain, $ varepsilon sb{ rm tu}$, has a significant effect on the computed results. If the value of $ varepsilon sb{ rm tu}$ is adjusted appropriately according to the element size, it can help eliminate the mesh sensitivity drawback. To adjust an appropriate value for $ varepsilon sb{ rm tu}$, two models have been used: (a) crack band model, as a function of the fracture energy, mesh size and tensile strength of concrete, and (b) a new proposed model as a function of only the element size. The analytical results obtained using the different models are compared with the experimental results; the proposed model gives good agreement. The proposed formula is very simple and can be used for both square and non-square elements. / The effect of steel reinforcement details on the general behaviour of the structure and its mode of failure, the criterion for using the rotating crack model versus the fixed crack model, and the importance of compressive strength degradation in the post-crack regime are established using detailed analysis of five shear panels tested by Vecchio and Collins (1982). The effect of a sudden drop of the stress after the tensile strength of concrete has been exceeded on the load-deflection response, the ductility ratio and the crack pattern for two high strength concrete beams are also examined. Further analyses of a squat shear wall and a shear panel are carried out to examine the reliability of the computer program HODA developed in this study for analysis of concrete structures under both monotonic and reversed cyclic loads. / Complete response of three structural walls in a low-rise building is studied under monotonically increasing loads until failure using the nonlinear finite elements program HODA. The influence of the tension-stiffening, steel strain-hardening on the load-deflection response and the ultimate load are studied for the case of the rectangular wall. The influence of smeared steel idealization and bar elements idealization on the wall response are also investigated. The ultimate loads of walls are compared with the values calculated using the current CSA Standard CAN3-A23.3-M84. (Abstract shortened by UMI.)

The post-punching failure response of reinforced concrete flat plate slab-column connections is investigated. The first part of this thesis discusses previous research on the tensile membrane action of reinforced concrete slabs and the use of structural integrity reinforcement to prevent progressive collapse after punching failure of slab-column connections. The second part of this thesis describes the design of a flat plate slab system that is the basis for slab-column connection test specimens. Two specimens were constructed and tested to determine punching failure resistance and post-punching failure resistance. The parameter investigated was the detailing of structural integrity reinforcement. Observations from testing contributed to the understanding of the post-punching resisting mechanism that developed. Three failure modes observed during testing were the yielding of reinforcing steel, concrete failure similar to the breakout of embedments, and pullout bond failure. The test results were compared to the predicted resistance of structural integrity reinforcement by CSA A23.3-04 (2004). The test specimens achieved 98% and 104% of the predicted resistance. Test results were also used to evaluate the equation proposed by Melo and Regan (1998) for concrete failure similar to the breakout of embedments, and the equation was found to underestimate the post-punching resistance of flat plate slab-column connections. / La réponse après-poinçonnement d’assemblages dalle-poteau de béton armé a été étudiée. Cette thèse constitue de deux parties dont la première discute les recherches précédentes sur l’effet des membranes en traction en plus de l’utilisation d’armature d’intégrité structurale de façon à éviter l’effondrement progressif après avoir subit un poinçonnement en cisaillement d’assemblage dalle-poteau. La deuxième partie décrit la conception d’un système formant d’une dalle plate qui sera la base des modèles d’assemblage dalle-poteau de cette recherche. Deux modèles ont été construits et testés à déterminer la résistance de poinçonnement en cisaillement et la résistance après-poinçonnement pour étudier le paramètre d’armature d’intégrité structurale.Les résultats expérimentaux obtenus ont contribués aux connaissances du mécanisme de résistance après-poinçonnement et trois modes de rupture ont été observés : le fluage de l’acier, la rupture du béton similaire aux brisures des ancrages, et l’échec du lien de retirement. Les résultats ont été comparés aux prédictions de la résistance d’armature intégrité structurale du CSA A23.3-04 (2004) et les modèles conçus ont obtenus 98% et 104% de la résistance prévue. De plus, ses résultats ont été utilisés pour évaluer l’équation proposée par Melo et Regan (1998) pour la rupture du béton similaire aux brisures des ancrages et cette équation a été déterminée à sous-estimer la résistance après-poinçonnement des assemblages dalle-poteau.

Socio-economic changes and employment decentralization in North America have transformed the traditional centrally-oriented travel pattern into a more complex many-to-many type, resulting in increased traffic congestion. / This research quantifies the impact of activity decentralization on road infrastructure requirements by super district and facility type. / The Supply Demand Linkage Model or 'SDLM', for a case study, relates the independent variable demand in passenger trips to the dependent variable the mean of traffic density in vehicles per kilometre. It is an aggregate travel demand model developed using a quasi experimental approach. This is accomplished through: (1) Extensive cross sectional analyses. (2) Calibration and validation of a travel demand model (EMME/2) requiring a large data base. (3) Variations in trip demand are implemented, using EMME/2, and the corresponding traffic densities are computed by super district and facility type. (4) Multivariate analyses relating supply-demand measures were implemented and produced the SDLM models which replace the trip assignment stage of travel demand models and compliments UTMS models at the sketch planning level. (5) Sensitivity analysis testing SDLM reliability against the EMME/2. (6) Application of the SDLM models through forecasting scenarios of employment and population to obtain the "Impact of employment decentralization in metropolitan road networks". / The multivariate analyses showed that variations in demand could explain 99.61% of the variations in traffic density at a 95% confidence level. And the sensitivity analyses demonstrated that the SDLM results are within 5% of actual values. The SDLM models may not be transportable but the established procedure is expected to be transportable. / The impact analyses has quantified the changes in travel pattern resulting from activity dispersion. This simplified procedure, transforms the SDLM models into a powerful tool.

A method of minimizing the total active disc area, required for the removal of soluble biochemical oxygen demand (SBOD), by a multi-stage rotating biological contactor (RBC) operating steady-state is proposed. Both deterministic and stochastic inputs are considered. / Total active disc area and the number of RBC stages are optimized for the deterministic case, and are then incorporated into a risk-based method of assigning per-stage active disc areas. The risk of the final stage SBOD exceeding a fixed effluent standard is evaluated by taking into account the variable nature of the influent flowrate and SBOD concentration. Bivariate normal, lognormal and shifted lognormal distributions are considered as models for the input random variables. The effluent SBOD probability density function is obtained according to the method of transformation of random variables. Illustrative examples are presented.

<p> This dissertation is about a consistent smooth <i><b>modeling of multidimensional nonlinear elastic and inelastic structural systems.</b></i> </p><p> First, the <i><b>One-Dimensional Smooth Hysteretic Model</b></i> <b> (1D SHM)</b> and its various features, such as, a) basic hysteresis, b) kinematic hardening, c) strength and stiffness degradations, d) pinching, e) gap-closing, and f) asymmetric yielding are reformulated in <i><b> time independent incremental form.</b></i> The areas, in which the SHM needed further advancements, such as: a) nonlinear post-elastic spring, b) modified Gaussian pinching, c) alternative pinching model using tangent function, d) variable gap length, e) degradation of post-elastic stiffness, and f) embedding variation of strength in the expression of tangent stiffness are developed. With these additional features 1D SHM can emulate some of the complex nonlinear behaviors of structural members adequately. </p><p> Further, a modified version of 1D SHM is re-formulated to simulate the <i><b> nonlinear elastic</b></i> behavior. Spectra for <i><b>nonlinear elastic and inelastic</b></i> structures are developed, using the modified SHM and the parent SHM, respectively. These spectra are generated for various strength reductions, and inherent and supplemental damping. The difference between the two types of damping is explained both theoretically and numerically. The nonlinear elastic formulation can be applied to evaluate and design of "weakened structures" structures equipped with novel negative stiffness devices (NSD). </p><p> The final part of the dissertation expands the multi dimensional plasticity model to 3D space frame elements that include strength and stiffness deteriorations, large deformations and rotations, using flexibility based corotational formulation and incremental multi-axial theory of plasticity. </p><p> In the first phase of the above research, <b>a new corotational formulation, based on flexibility modeling of space frames with large deformations and rotations, expanding prior developments,</b> is done. The new expansion incorporates a) coupled axial, flexural and shear deformations, b) rigid rotations of chords with respect to the stationary global reference frame, c) formulation of geometric stiffness matrix by taking variations of the force equilibrium equation, d) re-derivation of the entire formulation in time-independent incremental form, and e) inclusion of improved numerical techniques within the corotational system. Using the modified formulation, several elastic large deformation-rotations and buckling problems of space frames, previously solved by various researchers through stiffness based approach, can be analyzed. </p><p> The second phase of the forgoing research involved: <b>a) coupling between 3D geometric nonlinearity with large deformation and rotation, and multi-axial theory of plasticity, and b) incorporation of strength and stiffness deteriorations in the model.</b> The resulting model combines the classical <i> axial load-biaxial moment</i> (P-M-M) interaction, coupled with geometric nonlinearity. Standard <i>Newton method</i> of iteration scheme is employed to generate the <b>three dimensional hysteresis loops</b> for stress resultants and deformational variables. For cases, where the structure experiences plastic buckling (i.e. when the determinant of the global tangent stiffness matrix approaches zero due to coupled material and geometric nonlinearity), the arc length method, with modifications done for cyclic loading analysis, is used to track the cyclic buckling and post-buckling equilibrium paths. Finally, hysteretic energy based strength degradation and deformational ductility based stiffness degradation are incorporated in the yield surface based on P-M-M interaction and the elastic stiffness matrix, respectively. Several <b> benchmark examples</b> for 3D beams are presented to illustrate the above developments. (Abstract shortened by UMI.)</p>

Endocrine disruption is a problem of increasing environmental significance, as anomalies continue to be discovered in wildlife exposed to a variety of exogenous toxic compounds released into the aquatic environment through municipal and industrial effluents and agricultural runoff. The estrogens excreted by humans and entering aquatic systems via sewage treatment plants are of particular interest, as estrogen excretion cannot be feasibly controlled at the source and estrogens are among the most potent endocrine disruptors known. As phenolic compounds, estrogens are amenable to oxidation through the catalytic action of oxidative enzymes. Earlier work was directed toward characterizing the removal of estrogens using peroxidase enzymes as well as the fungal laccase Trametes versicolor in batch reactions. The ability of this laccase enzyme has been studied extensively and has demonstrated a very good ability to remove substrates such as phenol, bisphenol A and 17-beta estradiol (E2) from aqueous solutions. In order to minimize the amount of enzyme required to achieve effective treatment, this study focuses on characterizing the removal of E2 using immobilized laccase. Through this approach, it is anticipated that treatment costs will be reduced since immobilization permits the re-use of the active enzyme, rather than discarding the enzyme with treated solutions. The enzyme was immobilized by covalent bonding onto silica beads and the reactions were conducted in a bench-scale continuous-flow packed bed reactor. The influent concentration of E2 was 10 µM for most studies. The effects of mean residence time were determined for several influent E2 doses, and observable E2 transformation occurred under the reaction conditions employed. The stability and reactivity of the immobilized enzyme were observed over varying temperature and pH. As expected, conversion declined when the temperature of the system was changed from room temperature to near freezing at pH 5. / La perturbation des systèmes endocriniens est un problème qui gagne de plus en plus d'importance dans l'environnement naturel. Les scientifiques continuent de trouver bien des effets néfastes dans les poissons et la faune qui ont été exposé à une grande variété de composants toxiques ayant été rejetés dans les systèmes aquatiques à travers les effluents municipaux et industriels et le ruissellement agricole. Les estrogènes qu'excrètent les humains et qui se retrouvent ensuite dans les systèmes aquatiques après avoir passé à travers les usines de traitement d'eaux usées sont particulièrement intéressantes d'un point de vue de recherche car cette excrétion ne peut être contrôlé et les estrogènes comptent parmi les substances perturbatrices des systèmes endocriniens les plus néfastes. En tant que composés phénoliques, les estrogènes peuvent être oxydés et polymérisés dans des réactions catalysés par des enzymes oxydatifs. Des études précédentes avaient comme objectif de caractériser la transformation d'estrogènes catalysé par les enzymes peroxydase, ainsi que l'enzyme fongique laccase de Trametes versicolor dans la phase aqueuse. La capacité de l'enzyme laccase a déjà été étudié intensivement et celui-ci a démontré une bonne réduction de substrats nocifs tels que le phénol, le bisphénol A et le 17ß- œstradiol (E2) dans les solutions aqueuses. Afin de minimiser les quantités d'enzyme requises pour effectuer le traitement de E2, la présente étude a comme objectif de caractériser la réduction de E2 en utilisant le laccase immobilisé par liaisons covalentes sur de petites perles de silice dans un réacteur de taille laboratoire. Ainsi, il est prévu que les couts de traitement pourraient être réduits puisque l'immobilisation permet de réutiliser l'enzyme plutôt que de le jeter avec les effluents traités. Les effets du temps de résidence moyen dans le réacteur ont été étudiés pour quelqu

Wet-bond of hybrid carbon and glass fibre reinforced polymer (FRP) composites to cast-in-place concrete has been developed for a steel-free reinforced concrete structure. The prefabricated FRP is to serve as both stay-in-place form and external reinforcement, and the carbon and glass hybrid to provide suitable ductility in reinforcement. FRP formwork and cast-in-place concrete are connected through a fresh epoxy resin for a composite action. Since the new structure is solely dependent on the bond between FRP and concrete, a durable bond is of paramount importance. The purpose of this study is to examine the durability of wet-bond in comparison with dry-bond, which employs hardened concrete as substrate to evaluate their bond strength, bond mechanism and durability capacity. It was found that carbon-glass hybrid made significant contribution to ductility of composite materials. The curing of epoxy in the presence of fresh concrete had no negative effect on degree of curing (DOC) and glass transition temperature (Tg) of epoxy. The moisture in concrete, however, introduced water bubbles at epoxy surface that made the adhesive interface more porous and was responsible for relatively weak adhesion between epoxy and concrete in wet-bond samples. Bond strength of wet-bond is largely dependent on the mechanical interlock between the adhesive and aggregates. Of the varied environmental exposures: freeze-thaw cycling, continuous low temperature, wet-dry cycling and continuous hot moist conditions, the wet-bond technology is best suited to cold climate environments. Three typical failure modes of bond between hybrid FRP and concrete were modeled and the prediction was compared with experimental results. / Le composites hybrides faits de polymère renforcé de fibres de verre et de carbone (PRP) peuvent être utilisés comme renforcement externe et comme coffrage permanent avec du béton sans armature interne. Le béton est coulé en place en contact avec un époxy frais. Le comportement du composite hybride et la performance de l'adhésion de l'époxy frais au béton frais sont étudiés afin d'explorer la faisabilité de cette technique. L'utilisation de PRF hybride renforcé de fibres de carbone et de fibres de verre vise à fournir une ductilité appropriée au renforcement externe, alors que l'usage d'une adhésion époxy frais et béton frais (ou adhésion humide) vise à lier le PRF et le béton pour créer une action composite. L'importance d'une adhésion durable entre le PRF et le béton est primordiale pour la viabilité de la nouvelle structure. L'objectif de cette étude est d'examiner la durabilité dune adhésion humide en comparaison avec une adhésion sèche qui utilise le béton durci comme substrat, pour évaluer pour chaque cas la force d'adhésion, les mécanismes d'adhésion, et la durabilité. On a constaté pour le composite hybride carbone-verre a une contribution significative à la ductilité du composite. La cure de l'époxy en présence du béton frais, de l'époxy n'a aucun effet sur le degré de séchage et la température de transition du verre. Cependant, l'humidité du béton a causé le développement de bulles d'eau qui ont rendu l'interface plus poreuse, causant ainsi des réiens chimiques plus faibles dans le cas d'adhésion humide. La force de adhésion humide dépend largement des imbrications mécaniques entre l'adhésif et les granulats. Considérant de exposition environnementale comme les cycles de gel-dégel, les basses températures permanentes, les cycles humidification-séchage, et les conditions climatiques chaudes et humides, la technologie des adhésion humide convient mieux aux climats froids. Trois modes$

During planetary hot rolling of 304 austenitic stainless steel, cracks are formed along the plate edges. In order to explain the mechanism of edge cracking, the metallographical quantitative analysis of microstructural inhomogeneity of steel plates containing edge cracks of different intensities is performed. The austenitic matrix of the steel contained small amounts of delta ferrite inhomogeneously distributed across the width and the thickness of the plate. A correlation was found between ferrite content and edge cracking: the higher the ferrite content the longer the edge cracks. Among the chemical elements present in the steel, the most critical effect on delta ferrite content was exerted by carbon and nitrogen are a powerful gamma phase stabilizers at high temperature. To understand the effects of reheating parameters on the morphology and content of delta ferrite, the specimens selected from different locations of as-cast 304 stainless steel slab, were reheated according to the temperature profiles, which simulated the industrial reheating process before hot rolling. In general, reheating reduced the delta ferrite content, increased the size of the individual ferrite island and changed its shape to a more spherical. An increase of reheating time to 92 minutes caused drastic reduction in delta ferrite content and its further spherodization. Moreover, the size of the individual ferrite islands decreased. A possible, contribution of steel chemistry and reheating parameters to changes in the steel microstructure and the possibility of edge cracking, is discussed.

A study on the web-buckling behavior of castellated beams is described in this thesis. Both elastic and plastic methods of analysis are utilized to predict the failure modes of these beams. / Interaction diagrams predicting formation of plastic mechanisms, yielding of the horizontal weld length and elastic buckling analysis using the finite element method are correlated with a number of experimental test results from previous studies given in the literature. / Test-to-predicted ratios for a total of 42 test beams ranging from 45° to 60° openings are computed with the plastic and elastic methods of analysis, and a mean of 1.086 and coefficient of variation of 0.195 are obtained. A parameter study covering a wide range of 60° castellated beam geometries is performed to derive elastic buckling coefficients under pure shear and bending forces. An elastic buckling interaction diagram is then defined, which along with the diagrams utilized in the plastic analysis, can be used to predict the elastic buckling and plastic failure loads under any given moment-to-shear ratio. / To incorporate the effect of plasticity associated with buckling, expressions are derived to improve the previous theoretical models used, by combining both elastic and plastic results. This results in an improvement in the coefficient of variation of the test-to-predicted ratios or the 60° beams considered from 0.170 to 0.137.