<p>Many multi-story reinforced concrete frame structures were designed before the availability of current seismic design codes. The lateral load resistance of these structures may not be adequate even for a moderate earthquake due to the non-ductile reinforcement details of this type of structures. Recent post-earthquake investigations indicated that extensive damage occurs as a result of excessive shear deformation of the beam-column joints in the non-ductile frames, thus leading to full collapse of structures. The objectives of this study are to investigate the seismic behaviour of existing reinforced concrete frames under simulated seismic loading; as well as develop a rehabilitation technique for strengthening non-ductile frames. The first major part of the study is an experimental program conducted to: (i) investigate the inelastic behaviour of the non-ductile beam-column connections under cyclic loading; (ii) compare the response of the non-ductile beam-column connections with the response of beam-column connections designed according to the current concrete design code; and (iii) propose a practical method of rehabilitating existing connections and investigate their cyclic behaviour. The tested connections represent one-third scale model of existing connections. Six beam-column connections were tested under cyclic loading. The variables in the test specimens included the amount of joint and column transverse reinforcement and jacketing of the column only or both the column and the beam. Based on the test results, a design procedure is proposed for the rehabilitation of beam-column connections using corrugated steel jackets. The second major part of the study is to develop a suitable analytical procedure to simulate the behaviour of existing reinforced concrete joints so as to predict the proper behaviour of the non-ductile frames and develop a strategy for rehabilitation of such frames. Two joint elements are developed to represent the joint shear deformation and the beam reinforcing bar bond slip. The two elements are introduced into a non-linear dynamic analysis program which is used to simulate existing and rehabilitated frames. From the experimental and analytical research findings, recommendations for the design and detailing of the corrugated steel jacketing system for existing reinforced concrete frames are developed. In addition, a rehabilitation strategy is proposed to improve the performance of existing structures. The effects of the rehabilitation system on the confinement of beam-column connections, the provision of adequate development length for the positive bottom beam bars and the provision of full joint shear capacity are assessed and quantified. Test results indicated that corrugated steel jacketing system was found to be efficient in the rehabilitation of existing structures which do not meet the current seismic code requirements. A method is proposed for the design of the corrugated steel jacket to enhance the shear strength and ductility of the beam-column joint.</p> / Doctor of Philosophy (PhD)

<p>Dam safety is an important issue of current interest. In seismic regions, dynamic forces on the dam may be significant and may lead to crack initiation and propagation in the dam. A significant component of the dynamic forces is due to the hydrodynamic effects of the impounded water in the reservoir. The developed hydrodynamic force on the dam is highly dependent on the physical characteristics of the boundaries surrounding the reservoir including the reservoir bottom and sides. In this study, the effects of the reservoir boundary conditions on the seismic response of the dam are investigated. This study consists of four components. First, a mathematical model is proposed to account for the absorption effect of a sedimented reservoir bottom on the seismic response of the dam-reservoir system. Secondly, a study is conducted to examine the possibility of reducing the earthquake response of concrete gravity dams using hydrodynamic isolation at the dam-reservoir boundary. Thirdly, an analytical procedure is developed to compute the response of the hydrodynamic pressure and the seismic response of the dam impounding a reservoir of general shape and boundary conditions. Finally, the earthquake response of the dam was studied with special attention to the stresses in the dam. An index for the evaluation of the overall state of stress in the dam subjected to different load combinations is proposed. The dynamic component of stress and the proposed index in the dam are computed when the dam-reservoir system is subjected to different ground motion records. The effect of the reflected waves from underlying reservoir foundation rock on the calculated response of the dam when subjected to earthquake ground motion was found to be very important. It is concluded that the effect of the stiffness of a semi-infinite reservoir foundation on the reduction of the dam seismic response is more significant as compared to the dissipation effect of the sedimentation layer. It is shown that the isolation layer needs to be very soft and with sufficient thickness so as to effectively reduce the hydrodynamic pressure acting on the dam. The effects of the reservoir length and the type of boundary condition at the truncated reservoir boundary on the calculated response of hydrodynamic pressure were found significant. The proposed index for the stress in the dam (Stress Factor) was shown to have an acceptable correlation with the intensity of the input ground motion and can be used as a complementary design factor for seismic design of concrete gravity dams.</p> / Doctor of Philosophy (PhD)

<p>A study was conducted to investigate the dam-reservoir interaction effect on the linear and nonlinear seismic response of concrete gravity dams. A mathematical approach was developed for the solution of the coupled dam-reservoir interaction problem which can be implemented in the nonlinear seismic analysis of concrete gravity dams. Two methods of staggered solution procedures are proposed for the dam-reservoir interaction. Using Routh-Hurwitz criteria, both methods are shown to be unconditionally stable when the two differential equations of the fluid and structure include damping terms. The staggered pressure method was modified for use when the equation of motion includes a lumped (diagonal) mass matrix. A finite element program was developed to include the staggered solution schemes for seismic analysis of concrete gravity dams. The program considers the dam-reservoir interaction. The reservoir can be considered as infinite in which an appropriate boundary condition can be applied at the desired distance from the upstream face of the dam. The finite reservoir condition is also an option that can be included in the analysis. The effect of the travelling wave where nonuniform earthquake ground motion is applied to the boundary of the reservoir can be evaluated. The nonlinear analysis of the concrete gravity dam was considered based on nonlinear fracture mechanics crack propagation criterion. Seismic response of a concrete gravity dam subjected to travelling seismic excitation is investigated. The analysis is applied to the case of a gravity dam with infinite and finite reservoirs of different lengths to evaluate the effect of the travelling seismic wave on the dam crest displacement. Various wave speeds representing the speed of wave travel in the reservoir foundation, are used in the analysis. Earthquake waves are considered to travel in the upstream or the downstream directions. The nonlinear seismic fracture response of the Pine Flat dam is investigated under the effect of reservoir interaction. Smeared crack analysis model based on a nonlinear fracture mechanics crack propagation criterion was used to study the cracking behaviour of a concrete gravity dam. The staggered method is used to solve the dam-reservoir interaction problem and results of the analysis were compared with the case when the added mass was used to represent the interaction effects. An experimental program was conducted on small scale models of the concrete dam. A loading mechanism with two actuators was designed to apply four concentrated loads on the upstream face of the dam model. Dynamic load was applied cyclically by an actuator to represent the effects of the earthquake loadings. The static load which represent the hydrostatic pressure was kept constant. The material properties of the model was maintained the same as the prototype. In the proposed approach, the stress distribution at the top part of the dam model and prototype of the same material properties are found to be in close agreement.</p> / Doctor of Philosophy (PhD)

<p>This thesis deals with numerical modelling of the behaviour of soils infiltrated with fluids. The main objectives are to study the effect of viscosity of the fluid on the response of particulate media under static and dynamic loadings, and to examine the influence of partial saturation on the behaviour under undrained conditions. The latter study is relevant to low as well as high degrees of saturation.</p> <p>In the formulation incorporating the effect of viscous fluid, the effective stress principle is modified by including the shear stress developed in the fluid phase. As this shear stress depends on the rate of shear strains the overall response is rate dependent. The formulation is implemented in a finite element algorithm and a number of numerical examples, including dynamic creep at low and high stress levels, are provided.</p> <p>In the next part of this thesis, the liquefaction of saturated soils is investigated. In these studies the effect of viscosity of liquefied material on the stability of the soil-foundation systems under earthquake excitation is examined. Furthermore, the stability theory is reviewed and a simplified stability criterion is introduced. The problems of stability of a strip foundation and a soil column are analyzed.</p> <p>In the last pan, a mathematical formulation for the behaviour of partially saturated soils is implemented in the finite element algorithm and some boundary-value problems are solved. In order to examine the performance of the constitutive model, a series of experimental tests are carried out. Subsequently, the effect of partial saturation on the stability of soil-foundation systems is examined. The liquefaction phenomenon under earthquake loading is studied for the case of high degrees of saturation, while the bearing capacity of fine grained soils is analyzed for the case of low degrees of saturation.</p> / Doctor of Philosophy (PhD)

<p>A computer model is developed for the solution of regional network systems on a minimum cost basis. Different network problem types are identified to define the scope of the model. Generally, the problem involves the determination of the optimum conveyance schedule required to supply a set of consumer nodes with a commodity or public service provided by one or more processing centres (i.e. water supply, solid waste or wastewater collection networks). The system costs include costs incurred due to conveyance of material and the processing of that material; both of these cost components exhibit economies of scale and generally lead to the centralization of processing.</p> <p>A mathematical statement of the problem is developed which is applicable to all network types, can be utilized easily and efficiently in a digital computer and facilitates the use of a variety of optimization routines. A number of algorithms, ranging from linear approximation to nonlinear gradient search routines, are investigated for possible inclusion in the model with the advantages and disadvantages of each being identified.</p> <p>A modular package, NETSOL, is developed which facilitates the use of alternate optimization routines and allows for the inclusion of complex design functions in the computation of system costs. An interactive command structure permits the user to modify the network system parameters thereby combining intuitive design with the capacity to select an optimal solution from a large number of alternatives. Thus a model is obtained which is flexible enough to answer many of the questions that arise in network problems and also determine the optimum.</p> <p>In view of the disadvantages found in the existing optimization techniques (e.g. convergence to local minima), the properties of the network problems are investigated in detail to isolate any special characteristics. For a system involving separable concave cost functions, the minimum cost solution to a network problem lies at one of the vertices formed by the problem constraints. A new solution algorithm, HYVRST, is developed which takes advantages of this important property utilizing a direct search technique. This results in an efficient and stable algorithm with good convergence properties. A number of example are presented to test the optimization algorithms and demonstrate the usefulness of the NETSOL package in solving regional network problems.</p> / Master of Engineering (ME)

<p>A 2 inch diameter, conical-shaped glass hydrocyclone, operating without an air core, was used in this study. The geometric dimensions of the cyclone followed closely with the optimum design conditions determined for solid/liquid systems by Rietema (R-1) and used by Burrill and Woods (B-3) for liquid/liquid systems. Distilled water was used as the continuous phase. Dispersed oil phases studied include: butanol, methyl isobutyl ketone (MIBK) , toluene and kerosene.</p> <p>For each of the liquid/liquid systems, the efficiency of separation was determined as a function of volume split, oil/water phase ratio and feed flowrate. Differentiation of the liquid/liquid systems, in terms of physical properties, was based primarily on interfacial tension. Density difference and viscosity of the dispersed phase, were comparable from one system to another. Mixing energy used to disperse the oil phase in the water phase, geometric dimensions and temperature were constant throughout the work. The range of the operating variables were as follows:</p> <p>i) oil/water phase ratio 0.160 to 1.00</p> <p>ii) feed flowrate 100 to 365 mL/s</p> <p>iii) interfacial tension 2.0 to 30.0 mN/m</p> <p>iv) volume split 0.17 to 3.90</p> <p>For each system studied, photographs were taken at the inlet and outlets leading to and from the cyclone, respectively, to determine the drop size of the dispersed phase.</p> <p>The second part of the present work considered the influence that the mixing energy had on the effects of oil/water ratio and feed flowrate as studied in the first part.</p> <p>The efficiency of separation (Es ) is defined as follows:</p> <p>[equation removed]</p> <p>where Y and Q represent volume fraction of light phase and flowrate, respectively, while the subscripts denote specific orifice location on the hydrocyclone.</p> <p>From the first part the efficiency of separation in the cyclone was a very important function of volume split. The effect of the feed flowrate on separation in the cyclone was dependent on the interfacial tension. The effect of oil/water ratio was dependent on the rate of coalescence. Based on the photographic work, coalescence occurred in the cyclone for several of the systems studied.</p> <p>The majority of past work has varied the mixing energy with a change in the feed flowrate. As a result, drop size varied. Present work revealed that this reversed the effect that feed flowrate had on the separation in the cyclone with mixing energy constant.</p> <p>It was not possible to obtain two pure phases from the hydrocyclone for any of the systems studied. One pure phase, however, was achieved for three of the four systems studied. A relatively pure water phase (≥ 99%) was obtained at the underflow for the MIBK/water, toluene/water and kerosene/ water systems. The highest values of the optimum Es were 67, 57 and 62%, respectively, for each of these systems. For toluene/water and kerosene/water systems, the interfacial tension was sufficiently high to prevent significant drop breakup when the feed flowrate was increased. Under similar circumstances, drop breakup predominated for MIBK/water and butanol/water systems due to the lower values of interfacial tension. With butanol/water, a significant amount of light phase was found in the underflow. The optimum Es for this system was only 26%.</p> <p>It was noted that the efficiency of separation, Es, increased sharply at first and then decreased gradually with increasing volume split. The optimum volume split occurred at a value greater than the feed phase ratio for all systems studied. The optimum volume split occurred at a value ranged from 100 to 500% greater than the feed phase ratio. Since complete coalescence does not occur inside the cyclone, it is not possible to have the optimum split equivalent to the feed phase ratio. Continuous phase trapped in the interstides results in the optimum split equivalent to a value greater than the feed phase ratio. A simple mass balance model was used to describe the effects of volume split. From this model the interstitial volume could be inferred for all conditions. Combining this information with models for breakup, coalescence and hindered setting yielded a semi-quantitative explanation of all the trends observed.</p> <p>The feasibility of using the hydrocyclone to separate emulsions is based on achieving at least one pure phase. If this achievement is accomplished, then it is possible to reduce the volume requirement of a gravity settler. The role of the hydrocyclone is basically one of a preliminary stage in the physical separation process. If, on the other hand, it is not possible to have one pure phase, no useful purpose is served by the cyclone. Consequently, the butanol/water system can not be considered a feasible system to be separated by a hydrocyclone.</p> / Master of Engineering (ME)

<p>A theoretically sound and practical method of flexible pavement design remains one of the most needed, though widely unappreciated, aspects of transportation engineering. Papers presented at the Third International Conference on the Structural Design of Asphalt Pavements in 1972 greatly increased the awareness of design engineers of the testing problems involved in this field. The generated interest in rational, as opposed to empirical, flexible pavement design approaches brought about a pressing need for material characteristics for use in available theoretical modes.</p> <p>This study involved the development of laboratory equipment capable of providing values of resilient modulus, MR, and Poisson's ratio, v, of asphalitic concrete specimens. These properties are required as input for elastic layer analyses of flexible pavement systems. It was recognized that the developed equipement must be capable of providing reliable results at similar costs to conventional Marshall or Hveem tests, and should be adaptable to realistically simulate site conditions. It is considered that the equipment described herein satisfies these conditions.</p> <p>Test results on polymeric calibration samples compare favourably to those obtained during previous work on the resilient modulus of asphalt mixes. The testing program identified temperature, asphalt content and aggregate type as parameters that affect the resilient modulus. A future phase of this study onvolves a more comprehensice testing program in these areas, in addition to studying the effects of confining pressure and stress levels on material properties using equipment suggested from this initial testing program.</p> <p>Comparative design studies using available theoretical methods and generated stiffness parameters indicate possible cost savings as a result of thickness requirements for pavement systems comprised of mixes with higher MR values. Conventional empirical approaches do not permit similar thickness reductions for higher quality (strength) mixes.</p> / Master of Engineering (ME)

<p>This thesis deals with the estimation of wave directional spectra and applications to the study of surface gravity water waves. Theoretical foundations and testing procedures are established to evaluate and compare different methods of extracting the wave directional spectrum from a wave record. An integrated software package for the analysis of directional seas is developed and used to test all methods, and to identify their properties, characteristics and biases. As a result, guidelines for the use of these methods are drawn. The findings indicate that all of the methods currently used for wave directional spectrum estimation have drawbacks. As a result, three new methods are proposed and tested against current methods. Test results indicate that a proposed closed-form of the Maximum Likelihood Method is the best choice, from both a theoretical and computational point of view. The new method was shown to outperform all other estimates for both heave-pitch-roll and wavestaff data. Field data from the Atlantic Ocean, Lake Ontario and Lake St. Clair (spanning two orders of magnitude in size) is investigated in an attempt to demonstrate the resolution potential of the newly developed method of estimating the wave directional spectra. As a result, completely decoupled spectra are observed for the first time in rapidly turning winds, and a clear relationship between the wave relaxation parameter and the wave age is established. Directional spreading parameter values are found to be higher than the established values in previous studies, for both Lake Ontario and Atlantic Ocean data. In addition, the Atlantic Ocean directional spectra are found to be narrower than their Lake Ontario counterpart. Finally, wave measurements in Lake St. Clair indicate that the structure of directional spectra can be very complicated, even in small lakes, and that a strong shear current can cause not only the refraction of an incoming wavefield, but can also inhibit the generation of waves propagating directly against it.</p> / Doctor of Philosophy (PhD)

<p>ABSTRACT</p> <p>The first application of the tuned liquid damper (TLD) to mitigate the</p> <p>dynamic vibrations of structures was only around 20 years ago and has just been</p> <p>recently applied in North America. TLDs are partially fluid filled tanks (usually</p> <p>water) with a fundamental sloshing frequency tuned close to the frequency of the</p> <p>dynamic mode of structural vibration to be suppressed. Water alone is</p> <p>insufficient to achieve the level of damping typically required for design.</p> <p>Damping devices are often submerged in the water to greatly increase the inherent</p> <p>TLD damping. The damping device investigated in this study is a thin sharpedged</p> <p>horizontal-slat screen. TLDs with such screens of a particular solidity are</p> <p>designed for one target amplitude of structural response and have limited</p> <p>efficiency over a range of structural response. To increase the efficiency, the</p> <p>concept of smart screens is introduced in this study.</p> <p>Smart screens is the name given to a damping screen that alters its fluid</p> <p>pressure-loss characteristics at differing levels of excitation, (ideally) in a passive</p> <p>state of control. Symmetric fixed-angle screens and oscillating (rotating) parallellinked</p> <p>screens are experimentally investigated inside a rectangular TLD on a</p> <p>shake-table under sinusoidal motion in this study.</p> <p>TLDs have similar principles to common tuned mass dampers (TMD) and</p> <p>are analyzed accordingly. The TLD equipped with fixed-angle screens is</p> <p>modelled with linear numerical fluid models to simulate the TLD performance for preliminary design purposes. An inclined screen alters the pressure-loss</p> <p>characteristics from its typical vertical position, which in turn changes the</p> <p>inherent TLD damping, allowing damping to be controlled by simple screen</p> <p>rotation. The analytical models, including the utilization of a pressure-loss</p> <p>coefficient for an inclined horizontal-slat screen in oscillatory flow developed in</p> <p>this study, are compared with experimental results to verify their accuracy and</p> <p>ascertain limitations.</p> <p>Oscillating smart screens are investigated mainly for their practical</p> <p>consideration in a preferred passive mode of control. The screens rotate</p> <p>automatically with changes in fluid velocity (or excitation amplitude). Their</p> <p>ability to maintain a near-constant amount of TLD damping (or resonant energy</p> <p>dissipation) is examined. Other implementations of (passive) smart screens are</p> <p>possible and suggestions for future study are recommended.</p> <p>A TLD equipped with the mathematically modelled symmetric fixed-angle</p> <p>screens is theoretically investigated in a hypothetical structure-TLD system. This</p> <p>system demonstrates the ability of a smart screen to change its damping</p> <p>characteristics-altering the angle of inclination in this study-over a range of</p> <p>structural response thereby maintaining an optimal level of efficiency over a</p> <p>range of structural response accelerations.</p> / Master of Applied Science (MASc)

<p>The accuracy of the δ-MnO₂ method in determining Conditional Stability Constants (CSC's) for trace metal - organic complexes depends on the precise modeling of trace metal uptake by δ-MnO₂. Accordingly, characteristics of δ-MnO₂ and its adsorption behaviour for Cu were studied.</p> <p>Laboratory preparation of δ-MnO₂ is influenced by pH. A neutral redox process and an acid reduction of Mn⁺⁷ yield δ-MnO₂, but an alkaline oxidation of Mn²⁺ does not produce δ-MnO₂. Positive identification of MnOᵪ as δ-MnO₂ includes confirmation of characteristics such as x > 1.9, an adsorption capacity (ɼmax) ≥ 0.25 mol Cu/mol MnO₂, an amorphous XRD pattern, a specific TEM morphology and 1 < pHzpc < 2.</p> <p>Natural and simulated aging of δ-MnO₂ depends on temperature, pH and K content of the solid, and causes reduction of surface area and adsorption capacity by a factor 1.5 (natural) to 7 (simulated).</p> <p>Adsorption of trace metals onto δ-MnO₂ is described almost exclusively by a linearized Single Langmuir isotherm in the literature. This study found that Cu adsorption on δ-MnO₂ deviates from Langmuir linearity at low surface coverages. Explanations include the existence of two adsorption sites (Double Langmuir model) and non-constant activity of surface groups. The Implicit Langmuir expression is derived from surface complexation theory to model the latter, and has the form:</p> <p>[equation removed]</p> <p>where ɼads (= mol Cu adsorbed/mol MnO₂) and the free Cu²⁺ concentration in solution are measured. r ,B and n are the adsorption parameters. This model predicts the observed deviation from linearity. The bindings energy depends on the pH, the H⁺/Cu²⁺ exchange ratio (n), the surface coverage (ɼads/ɼmax) and a constant B.</p> <p>Adsorption isotherms were obtained over a pH range of 6 to 8.5, and a Cutotal range of 1 - 40 μM with glycine added to prevent precipitation of Cu. Adsorption results were fitted to Single, Double and Implicit Langmuir models, and compared. The Implicit Langmuir model describes Cu uptake by δ-MnO₂ most accurately, and CSC's for Cu-NTA and Cu-glycine complexes were readily determined using this model.</p> <p>¹⁴C studies indicated that NTA, glycine and aspartic acid do not adsorb on δ-MnO₂.</p> / Doctor of Philosophy (PhD)