Adsorption experiments using both monosodium methanearsonate (MSMA) and its inorganic degradation by-product species As(+5), as sodium arsenate Na2AsO4, were conducted to evaluate the sorptivity of these constituents to various fractions of soil samples taken from the West Palm Beach Country Club. Adsorption data were analyzed with common isotherm equations (i.e., Linear, Freundlich, Langmuir) to determine Kd for each arsenic (As) species/soil fraction. Simulations using a one-dimensional pesticide transport model, PRZM 2.0, were completed to evaluate possible dissolved concentrations of arsenic at the water table interface under 8 different application scenarios for the soil profile found at the sample site. All contaminant/soil systems displayed a linear sorptivity relationship (R2 ranging from 0.8262 to 0.9779) with Kd values (units of L/g) ranging from 0.0102 to 0.2295. Results also indicate As(+5) had a higher affinity for the soil fractions than MSMA. PRZM-2.0 predicted concentrations of dissolved arsenic at the water table interface from 0.04 to 1018 ppb within 1 month from only 1 application. Florida's MCL for dissolved as in groundwaters is 50 ppb. It is recommended that the registration and use of MSMA be re-evaluated as it may impact ground water quality at golf courses or other sandy aquifer systems.

The introduction of aquatic nuisance species (ANS) and bacterial pathogens from discharge of ballast water by sea-faring vessels is an ongoing problem that threatens ecosystems and human health. This study investigates the disinfecting capability of ferrate in a marine environment on several organisms listed in international standards for ballast water management. Organisms were grown in a saline solution and were treated with dosages of ferrate ranging from 0.25-5.0 mg/l. A ferrate dose of 5 mg/l resulted in almost complete kill for all organisms tested. Smaller dosages have also been very effective, particularly if all organic material from the nutrient broth used to cultivate them is removed by washing the cells with saline solution. Ferrate appears to act very quickly, with tailing occurring after about 5-15 minutes. Analyses of the data with the CT approach, the Chick-Watson and Hom's models, and an oxidant demand equation derived from equations recommended by the Water Environment Federation (WEF) are in good agreement that ferrate concentration is more important than contact time. The Hom's model appeared to most accurately represent the action of ferrate on these organisms. Salinity and pH did not adversely affect results, and regrowth was not a problem. Two measures to reduce clumping did not eliminate the observed tailing effect, suggesting a different mechanism for this phenomena. These preliminary tests indicate that ferrate could be a very effective disinfectant in the treatment of ballast water, and the short half-life of ferrate is an advantage, since the ballast water is subsequently released into the environment.

<p>Provisions for the design of masonry walls is subject to uniformly distributed pressure normal to the surface of the wall differ significantly from country to country. These differences may be attributed both to differences in design philosophy and to a general lack of conclusive or widely accepted experimental and analytical research. Most of the previous research in this area was concerned with brick masonry and with practical rather than well defined support conditions. Also, the available design methods were not accurate or rational. Therefore, this study was initiated to investigate the flexural behaviour of hollow concrete block masonry both experimentally and analytically and to assess the design methods for laterally loaded walls.</p> <p>The experimental program included 30 full scale wall tests representing different support conditions and aspect ratios. In addition, stack bonded prisms and wallettes were used to determine the flexural tensile strengths. The full scale tests were performed using a test facility designed to accommodate tests of masonry panels up to 6.0 m long by 3.6 m high and to provide well defined support conditions. The observed behaviours of the walls were compared to other walls of the same series and to other tests to investigate the effects of variability, aspect ratio, support conditions, and the presence of either precompression along the top panel or precracking near the panel center.</p> <p>A nonlinear finite element model capable of reproducing the observed behaviour of the walls was developed and used to extend the knowledge of masonry wall behaviour to include untested conditions and configurations. In this model, the anisotropic nature of the masonry, the nonlinearity due to cracking, and the effects of the transverse shear were taken into considerations. Also, the existing biaxial failure criteria were examined and proposed macroscopic biaxial failure criterion was incorporated in the finite element model to predict the strengths and the failure modes for masonry assemblages. This criterion accounted for the anisotropic and composite nature of masonry and was based on physical interpretations rather than being strictly a phenomenological criterion.</p> <p>Finally, the available design methods were compared using the extended data from the analytical model and design a method based on elastic plate theory was proposed. This method was rationally developed to predict first cracking and failure capacities for masonry panels simply supported on three or four sides for a wide range of aspect ratios.</p> / Doctor of Philosophy (PhD)

The oxidation kinetics of m-substituted phenols by TiO2/UV were investigated. An attempt was made to correlate Swain-Lupton parameters (R) for aromatic substituents with the oxidation kinetic constants, based upon molecular structure and reactivity theory. Irradiation experiments were carried out with suspended aqueous TiO 2 powder and substrate mixture in a Rayonet Photochemical Reactor. Langmuir-Hinshelwood model was applied to obtain apparent kinetic rate constants. A linear correlation is observed between Langmuir-Hinshelwood kinetic parameters and Hammett constants for m-chloro, m-bromo and m-fluoro phenols. The changes in p values of Hammett plots at pH 3 suggest that the main degradation pathway may involve a positively charged intermediate, such as a radical cation formed by direct electron transfer to the positive holes at low pH. At high pH levels, however, substrate speciation, surface charge of the semiconductor, and bandgap shift appear to lead to a change in the degradation mechanism.

This study investigated microfiltration of Lake Michigan Water for the production of drinking water. A 60 gpm Memcor microfiltration pilot plant was operated for nine months at Manitowoc, Wisconsin to determine and model the performance characteristics of a microfiltration pilot plant for varying surface water conditions. Statistical regression and modeling was used to determine and develop quantitative relationships between time of operation and several operational variables for water quality and productivity. Modifications of Darcy's Law and flux decline data were used to develop a model relating temperature and flux to cleaning frequency. Statistical hypothesis testing and associated modeling were used to determine if relationships existed between the water quality and the independent operating variables affecting microfiltration. The study demonstrated that the filtered water turbidity or particle count did not carry with the flux or the influent water temperature and that the degree of turbidity or particle count removal was dependent on the raw water turbidity or particle count. Direct filtration of an alum pretreated feed water was found to greatly increase time of operation between cleanings for temperatures below 48 degrees F. As expected the size exclusion membrane process was found to have no effect on dissolved of diffusion controlled solute rejection. the investigation found the turbidity and particle counts of the microfiltered water was less than the same for the finished water produced by the conventional alum coagulation, sedimentation and filtration process. The investigation demonstrated that microfiltration could be used to consistently produce a drinking water that met or exceeded state or federal requirements at Manitowoc. Based on the results of this investigation, a recommendation was made to use microfiltration as the treatment process of choice for the treatment of Lake Michigan Water.

<p>Design of earthquake-resistant structures has been an important area in both research and engineering practice for decades. Realistic determination of seismic loading on structures is one of the governing design criteria for design of new buildings or evaluation of existing structures. For the nuclear industry, the performance of structures is extremely important owing to public safety concerns.</p> <p>This report explores the methodologies used to calculate seismic-induced soil pressure applied onto partially embedded structures. A critical review was performed on different methods developed in the past, which includes simplified analytical approaches based on either yielding wall theory or rigid wall theory and detailed dynamic analysis with the consideration of soil-structure interaction effects. Assumptions, range for appropriate application, and corresponding shortcomings of these methods are identified. Several critical issues that have significant impact on the soil-structural response but are not sufficiently taken into account in most existing models, are identified. These include embedment effects, interface boundary conditions and material nonlinearity. Following the review, a detailed seismic analysis using the finite element method is carried out to explore the effects of embedment effects, interface boundary conditions and material nonlinearity on seismic earth pressure. A simplified CANDU 6 reactor building excited by an artificial strong ground motion is used in this analysis. The seismic earth pressures obtained from this detailed seismic analyses under various conditions are then compared with the simplified approaches to evaluate their accuracy.</p> / Master of Engineering (ME)

<p>The report describes an interactive computer program that can be used to determine the steady state piezometric surface profile for given flow conditions in various hydraulic networks. The program is designed for use in a time-sharing mode to facilitate the setup, calibration and modification of cross-sectional data defining a hydraulic network. The network may include open channels (either natural or man made) or closed conduits, or both, in configurations of single reach, multiple tributaries or bifurcated branches with its resultant "island" flows. In addition, bridges, weirs, culverts and manholes can be modelled as transitional structures. There is a choice of six resistance laws which are selected during run time. The network geometry file is stored on secondary devices such that relatively large systems can be handled on computers of moderate size. A large part of the report comprises a set of Appendices which can serve as independent manuals for the use and modification of the programs.</p> / Master of Engineering (MEngr)

<p>In frame structures, the multi-directional motion of an earthquake has a significant effect on the structure response. The columns, especially those at the building corners, are subjected to biaxial bending from combined longitudinal, transverse, and torsional motion of the structure, with added axial loads due to overturning. Moreover, the variation of the axial forces may be independent of the variation of the other lateral forces.</p> <p>The non-ductile response of structural elements, particularily columns, has been the cause of numerous failures during earthquakes. The non-ductile behaviour of reinforced concrete columns arises from different causes such as insufficient anchorage length and bond for the longitudinal steel bars with concrete, insufficient confinement, or inadequate shear strength.</p> <p>The objective of this research program is to analytically and experimentally evaluate the non-linear behaviour of non-ductile reinforced concrete columns under lateral cyclic deformations. The experimental data was used to verify the analytical predictions.</p> <p>The analytical phase of this study included the development of an upgraded 3D beam-column element based on lumped plasticity modelling. The model accommodates flexural response by quadrilinear force-deformation relationship, and shear response by strength and stiffness degrading relationship. The model takes into account the effect of axial load variation on lateral deformation and its interaction with biaxial moments and shear, which is an important contribution.</p> <p>The 3D model was validated using experimental data available in the literature by several independent researchers for reinforced concrete columns. The calculated and experimetnal results were encouragingly close, especially considering the complexity of the response. The effect of different axial load variation paths on the response of cyclically loaded columns was studied.</p> <p>A new analytical procedure to obtain the moment-rotation and force-deflection relationships for reinforced concrete columns was developed. These relationships were used as input data for the 3D element. This procedure uses the basic mechanical and geometrical properties of the element. This procedure uses the basic mechanical and geometrical properties of the element. It takes into consideration the effect of bond-slip of tensile bars, buckling of compression bars as well as flexure and shear deformations. This procedure was verified using available experimental data. The comparision showed good agreement. A parametric study to evaluate the effect of variation in section and material properties was also conducted.</p> <p>The experimental phase of this study included testing three reinforced concrete short columns under cyclic lateral loads and constant axial load. The first specimen, which represents columns designed according to current code (CSA A23.3-94), failed in a non-ductile shear manner. The second specimen was identical to the first one but rehabilitated using anchored carbon fibre reinforced polymers (CFRP). A significant increase in the displacement ductility of the column was achieved. The third specimen represents a non-ductile short column designed according to pre-1970 codes and rehabilitated using anchored CFRP wraps. Increased ductility was achieved. Two different techniques to reduce concrete bulging at column sides were evaluated in the two rehabilitated specimens; namely, by using through steel rods and fibre anchors. Both techniques proved to be effective.</p> / Doctor of Philosophy (PhD)

<p>Field and laboratory investigations were carried out to explore sediment oxygen demand (SOD) and its component parts. An in situ measurement device was built, tested and applied in Hamilton Harbour. Techniques were developed to measure SOD and oxygen uptake by chemical oxidation (CSOD). Sediment samples were taken from Hamilton Harbour and seven other lakes in Northern Ontario and Cape Breton Island. All samples were analyzed for organic content and selected samples were placed in laboratory columns. Experiments were conducted in which oxygen uptake was measured within the columns under controlled conditions. Sediment oxygen demand was fractioned into portions attributable to chemical oxidation, biological respiration and direct macroinvertebrate respiration.</p> <p>Models were selected to describe the dependence of each portion of SOD on oxygen concentration and temperature. Where possible, mechanistic explanations are presented for the models selected. Results indicate that the chemical portion of SOD is dependent on oxygen concentration in the manner of a first-order reaction and that it responds to temperature change in a manner typical of a mixed bacterial community. At high oxygen concentrations, anaerobic metabolic activity is found to be the limiting factor in CSOD. Bacterial and macroinvertebrate oxygen uptake are dependent on oxygen concentration at low concentrations, following a Monod kinetic form. These fractions respond to temperature in the same fashion as the chemical portion. Macroinvertebrates contribute a large part of the direct respiration as well as having a profound effect on the total community respiration.</p> / Master of Engineering (ME)

<p>In the application of cold formed steel structural members, holes are usually cut in the webs of sections for passing pipes or conduits. The Canadian standard for the design of cold formed steel sections does not provide sufficient design information for theses conditions. However, the American Iron and Steel Institute has recently provided design guidelines for sections with circular perforations based on limited available experimental data.</p> <p>The purpose of this study is to determine the effect of size and shape of openings on the axial load behaviour of cold formed sections having different flat width-to-thickness ratios of webs.</p> <p>A total of fifty five stub column tests were performed to provide design guidelines for stiffened plates with openings. Cold formed lipped channel steel sections were selected for the tests. Circular, square or slotted holes were cut in the centres of webs. The diameter, or width of the openings, varied from 0 to 0.6 times the flat width of the web. The tests were performed under axial compression and centering of the specimen was done with the help of strain gauges. Load versis axial shortening and out-of-plane deflections curves are plotted. Experimental buckling loads of the sections are obtained using the strain reversal method. Ultimate loads of the stub columns are calculated using the effective width approach given in North American codes. An empirical relationship was derived from the experimental data for the effect of square of circular openings in the web on the strength of cold formed sections.</p> <p>It was found that the buckling load of a section decreases with respect to the buckling load of an unperforated section when size (diameter or width) of the opening is 20% of the flat width of the web but increases as the size of the opening is increased to 60%. The ultimate strength of sections with circular and square openings changes insignificantly when the size of the openings is 20% of the flat width of web. However, it drops to about 87% when the opening size is increased to 60%.</p> <p>The shape of the opening influences the degree of reduction in strength. The shapes in increasing order of influence are circular, square and slotted openings. The maximum drop in compressive strength, about 14%, was for the section with a slotted opening, of width of about 48% of the web flat width. It also shows the importance of both the longitudinal and transverse dimensions of the opening. The design guidelines provided by the American Iron and Steel Institute (1986) are conservative. The equation proposed herein accurately predicts the effect of square or circular perforations on the strength of the cold formed steel sections.</p> / Master of Engineering (ME)