Performance of bridges during previous earthquakes has demonstrated that many structural failures could be attributed to seismic deficiencies in bridge columns. Lack of transverse reinforcement and inadequate splicing of longitudinal reinforcement in potential plastic hinge regions of columns constitute primary reasons for their poor performance. A number of column retrofit techniques have been developed and tested in the past. These techniques include steel jacketing, reinforced concrete jacketing and use of transverse prestressing (RetroBelt) for concrete confinement, shear strengthening and splice clamping. A new retrofit technique, involving fibre reinforced polymer (FRP) jacketing has emerged as a convenient and structurally sound alternative with improved durability. The new technique, although received acceptance in the construction industry, needs to be fully developed as a viable seismic retrofit methodology, supported by reliable design and construction procedures. The successful application of externally applied FRP jackets to existing columns, coupled with deteriorating bridge infrastructure, raised the possibility of using FRP reinforcement for new construction. Stay-in-place formwork, in the form of FRP tubes are being researched for its feasibility. The FRP stay-in-place tubes offer ease in construction, convenient formwork, and when left in place, the protection of concrete against environmental effects, including the protection of steel reinforcement against corrosion, while also serving as column transverse reinforcement. Combined experimental and analytical research was conducted in the current project to i) improve the performance of FRP column jacketing for existing bridge columns, and ii) to develop FRP stay-in-place formwork for new bridge columns. The experimental phase consisted of design, construction and testing of 7 full-scale reinforced concrete bridge columns under simulated seismic loading. The columns represented both existing seismically deficient bridge columns, and new columns in stay-in-place formwork. The existing columns were deficient in either shear, or flexure, where the flexural deficiencies stemmed from lack of concrete confinement and/or use of inadequately spliced longitudinal reinforcement. The test parameters included cross-sectional shape (circular or square), reinforcement splicing, column shear span for flexure and shear-dominant behaviour, FRP jacket thickness, as well as use of FRP tubes as stay-in-place formwork, with or without internally embedded FRP crossties. The columns were subjected to a constant axial compression and incrementally increasing inelastic deformation reversals. The results, presented and discussed in this thesis, indicate that the FRP retrofit methodology provides significant confinement to circular and square columns, improving column ductility substantially. The FRP jack also improved diagonal tension capacity of columns, changing brittle shear-dominant column behavior to ductile flexure dominant response. The jackets, when the transverse strains are controlled, are able to improve performance of inadequately spliced circular columns, while remain somewhat ineffective in improving the performance of spliced square columns. FRP stay-in-place formwork provides excellent ductility to circular and square columns in new concrete columns, offering tremendous potential for use in practice. The analytical phase of the project demonstrates that the current analytical techniques for column analysis can be used for columns with external FRP reinforcement, provided that appropriate material models are used for confined concrete, FRP composites and reinforcement steel. Plastic analysis for flexure, starting with sectional moment-curvature analysis and continuing into member analysis incorporating the formation of plastic hinging, provide excellent predictions of inelastic force-deformation envelopes of recorded hysteretic behaviour. A displacement based design procedure adapted to FRP jacketed columns, as well as columns in FRP stay-in-place formwork provide a reliable design procedure for both retrofitting existing columns and designing new FRP reinforced concrete columns.

This thesis introduces performance and power optimization techniques for caches. Our optimization techniques target both conventional caches, which are implemented using six-transistor (6T) cells, and highly reliable caches implemented using eight-transistor (8T) cells. In 6T cell caches, we enhance leakage power dissipation by adapting a previous proposed technique, Drowsy Cache, according to the application behavior. We show that spatial locality in embedded applications is low and Drowsy Cache misses a significant leakage power saving opportunities. By taking a finer granularity approach, we achieve a significant leakage power reduction with minimal performance overhead. Although 6T cell caches are commonly used, we show that they are not proper choice for future designs due to poor stability. We investigate 8T cells as alternative reliable designs for implementing caches. However, Column Selection Issue limits efficiency of 8T cells during write operations. Previous solution, Read-Modify-Write (RMW), addressed column selection issue by requiring a read operation before each write operation, imposing significant overhead on performance, cache traffic, and power. We observe that a significant share of cache accesses in RMW is either redundant or unnecessary, consequently can be avoided without compromising program execution consistency. Based on our observations, we propose two techniques which exploit a buffering mechanism to detect and filter out unnecessary and redundant cache accesses. Our simulation results show that our techniques improve performance and cache traffic effectively in 8T cell caches. Furthermore, we propose a novel dual threshold 8T cell which reduces leakage power significantly with negligible impact on performance. Our proposed cell also improves stability and robustness to process variations compared to the conventional 8T cells. / Graduate / 0544 / farahani.mostafa@gmail.com

In the past few years, some experimental investigations have been conducted to verify seismic behaviour of fiber reinforced polymer reinforced concrete (FRP-RC) beam-column joints. Those researches were mainly focused on exterior beam-column joints without lateral beams. However, lateral beams, commonly exist in buildings, can significantly improve seismic performance of the joints. Moreover, the way the longitudinal beam bars are anchored in the joint, either using headed-end or bent bars, was not adequately addressed. This study aims to fill these gaps and investigate the shear capacity of FRP-RC exterior beam-column joints confined with lateral beams, and the effect of beam reinforcement anchorage on their seismic behaviour. Six full-scale exterior beam-column joints were constructed and tested to failure under reversal cyclic loading. Test results showed that the presence of lateral beams significantly increased the shear capacity of the joints. Moreover, replacing bent bars with headed-end bars resulted in more ductile behaviour of the joints.

Landfills are considered to be one of the major sources of anthropogenic methane (CH4) emissions in the environment. A landfill biocover system optimizes environmental conditions for biotic CH4 consumption that controls the fugitive and residual emissions from landfills. A compost material has more oxidation potential in comparison to any other material due to its high porosity, organic content, free flux for gases and water holding capacity. Thermal, hydraulic, bio – chemical and mechanical (THMCB) properties are important factors that can significantly affect the performance of biocover material with regards to CH4 oxidation potential as well as structural stability. Technical data on the thermal, hydraulic and mechanical (THM) properties of compost based biocover materials are quite limited. Hence, a detailed experimental program has been carried out at the University of Ottawa to study the THM properties and behaviour of compost biocover material by conducting experimental tests on small compost samples as well as by performing column experiments. The test results indicate that lower water content (dry of optimum for compaction curve) shows more free air space (FAS) in comparison to higher water content. The compost has almost the same shear strength for various initial water contents and dry unit weights; however, it settles and swells more at higher water content than lower water content per mechanical test results. The thermal and hydraulic properties of compost are a function of the compaction degree in addition to various other parameters. It is also found that the THM properties of compost are strongly coupled and the degree of saturation greatly affects the FAS.

Chromium (VI) is a pervasive groundwater contaminant that poses a considerable threat to human health. Remediation techniques have focused on the reduction of the highly mobile Cr(VI) to the sparingly soluble, and less toxic, Cr(III) species. Traditionally, remediation performance has been evaluated through the measurement of Cr(VI) concentrations; however, this method is both costly and time-consuming, and provides little information regarding the mechanism of Cr(VI) removal. More recently, Cr isotope analysis has been proposed as a tool for tracking Cr(VI) migration in groundwater. Redox processes have been shown to produce significant Cr isotope fractionation, where enrichment in the ⁵³Cr/⁵²Cr ratio in the remaining Cr(VI) pool is indicative of a mass-transfer process. This thesis describes laboratory batch and column experiments that evaluate the Cr isotope fractionation associated with the reduction of Cr(VI) by various materials and under various conditions. Laboratory batch experiments were conducted to characterize the isotope fractionation during Cr(VI) reduction by granular zero-valent iron (ZVI) and organic carbon (OC). A decrease in Cr(VI) concentrations was accompanied by an increase in δ⁵³Cr values for the ZVI experiments. Data were fitted to a Rayleigh-type curve, which produced a fractionation factor α = 0.9994, suggesting a sorption-dominated removal mechanism. Scanning electron microscopy (SEM), X-ray absorption near-edge structure (XANES) spectroscopy, and X-ray photoelectron spectroscopy (XPS) indicated the presence of Cr(III) on the solid material, suggesting that reduction of Cr(VI) occurred. A series of batch experiments determined that reaction rate, experimental design, and pre-treatment of the ZVI had little to no effect on the Cr isotope fractionation. The interpretation of isotope results for the organic carbon experiments was complicated by the presence of both Cr(VI) and Cr(III) co-existing in solution, suggesting that further testing is required. A laboratory column experiment was conducted to evaluate isotopic fractionation of Cr during Cr(VI) reduction by OC under saturated flow conditions. Although decreasing dissolved Cr(VI) concentrations also were accompanied by an increase in δ⁵³Cr values, the isotope ratio values did not fit a Rayleigh-type fractionation curve. Instead, the data followed a linear regression equation yielding α = 0.9979. Solid-phase analysis indicated the presence of Cr(III) on the surface of the OC. Both the results of the solid-phase Cr and isotope analyses suggest a combination of Cr(VI) reduction mechanisms, including reduction in solution, and sorption prior to reduction. The linear characteristic of the δ⁵³Cr data may reflect the contribution of transport on Cr isotope fractionation.

The purpose of this study is to model and analyze the nonplanar shear wall assemblies of shear wall-frame structures. Two three dimensional models, for open and closed section shear wall assemblies, are developed. These models are based on conventional wide column analogy, in which a planar shear wall is replaced by an idealized frame structure consisting of a column and rigid beams located at floor levels. The rigid diaphragm floor assumption, which is widely used in the analysis of multistorey building structures, is also taken into consideration. The connections of the rigid beams are released against torsion in the model proposed for open section shear walls. For modelling closed section shear walls, in addition to this the torsional stiffness of the wide columns are adjusted by using a series of equations. Several shear wall-frame systems having different shapes of nonplanar shear wall assemblies are analyzed by static lateral load, response spectrum and time history methods where the proposed methods are used. The results of these analyses are compared with the results obtained by using common shear wall modelling techniques.

Solid-liquid contact angle is an important parameter in many particulate processes of the mineral, ceramic and chemical industries. In particular, modification of the contact angle through surface active agents plays a crucial role in froth flotation of minerals. In the case of flat solid surfaces, direct measurement of the contact angle is possible. However, such flat surfaces can not be obtained with finely divided solids typically encountered in flotation applications. Then, indirect methods based on powder beds as thin layers of powders deposited on glass plates or packed columns are used for the determination of apparent contact angles. This thesis presents an alternative novel method based on the capillaric dewatering of filter cakes for the measurement of the receding contact angle and correlates the contact angles measured as such with column wicking and micro-flotation test results of zircon and rutile mineral particles. The experimental procedure is simple and fast. The results have proven that the proposed method is reliable and give a good measure of the contact angle in the absence and presence of surface active non-wetting agents.

In Turkey, in most of the reinforced concrete buildings, hallow masonry infill walls are used as a non-structural element, during design stage, their contribution to overall building behavior is not well known. Observations made after the earthquakes revealed that these non-structural elements had beneficial effects on the lateral capacity of the building. In this study, the contribution of the hallow masonry infill walls to the lateral behavior of reinforced concrete buildings was investigated. For this purpose, two different buildings were chosen as case studies. Three and six story symmetric buildings are modeled as bare and infilled frames. The parameters that were investigated are column area, infill wall area, distribution of masonry infill walls throughout the story. To determine the effect of each parameter, global drift ratios are computed and are compared for each case.

Bitumen recovery by the water-based extraction process produces waste streams known as tailings. When discharged into the tailing ponds, the coarse solids in the tailings stream settle out quickly, while the fine solids accumulate over years of settling to a solids content of 30-35% by weight. The formed fluid fine solids sludge, known as mature fine tailings (MFT), traps 1-3% by weight hydrocarbons within its stable slurry structure. The remediation of these mature fine tailings is one of the major challenges facing the oil sands industry. This study was intended to investigate the recovery of residual hydrocarbons in the MFT by froth flotation process. Using a laboratory Denver flotation cell operated in a batch mode, the effect of MFT dilution ratio by process water or tap water, the flotation hydrodynamics and aeration rate on hydrocarbon recovery kinetics was studied. It was found that at 1:2 dilution by weight of the MFT with process water, increasing aeration rate has a more favourable effect on recovering more than 85% of the hydrocarbons from the MFT. The hydrocarbon-rich froth produced was treated by naphtha and was found to produce a hydrocarbon product similar to diluted bitumen obtained in bitumen extraction process, suitable for upgrading. Similar approach was applied to the hydrocarbon-rich tailings from the Tailings Solvent Recovery Unit of paraffinic froth treatment. Satisfactory recovery of hydrocarbons from the MFT was obtained using a flotation column operated in a continuous mode, confirmed the results obtained from the batch tests. The tailings produced from the continuous flotation experiments were treated with polymer flocculants such as Magnafloc-1011 and Al-PAM to study the effect of hydrocarbon recovery on the remediation of the MFT. The results from initial tests showed that both flocculants were not as effective on flocculating MFT solids following the recovery of hydrocarbons by froth flotation. / in Chemical Engineering

Steel moment frames are often used in structures to provide lateral strength and stiffness to the structure. These frames are subject to failure modes including buckling in the out of plane direction in a lateral-torsional buckling mode. This failure mode is influenced by interactions of the members through their connections. While the flexural behaviour has been studied in depth and for some time, the effect of torsional warping interaction between members has not been studied extensively. This work presents an analysis of the effect of including the effects of warping interaction or neglecting them, as is done in the current design practice. The issues of inelastic behaviour are considered, as well as the case of torsionally sensitive members. A joint element model is created to treat the warping displacements and their continuity through the joint. The study finds that the current practice of neglecting the warping displacement continuity appears to be a conservative assumption. It is recommended that the present practice of neglecting the effects of warping in analysis of frames continues. / Structural Engineering