bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of proposed Glengowan Dam flow augmentation on Thames River water quality
Authors: Gowda T. P. Halappa , Dewey R. J.
Published: January 2010

The Thames River water management study report, prepared in 1975 by the Ontario Ministries of Natural Resources and Environment, recommended the construction of the Glengowan Dam primarily for flow augmentation to improve the river water quality (Recommendation No. 1). As part of the environmental impact assessment of the proposed dam, detailed water quality prediction studies were carried out using deterministic and stochastic models to evaluate the impact of the proposed flow augmentation and wastewater loading options. The river receives treated wastewater effluents from five water pollution control plants (WPCP) in the study area, all located within the City of London. The processes simulated by the models include advection, decay of carbonaceous and nitrogenous oxygen demand (CBOD and NOD), sediment oxygen demand, atmospheric reaeration, and respiration and photosynthetic activity of aquatic macrophyte community. The options modelled include (a) projected CBOD and NOD loading rates from the five WPCP's for the planning period 1981–2001; (b) low flows attainable with augmentation from existing Fanshawe reservoir and the proposed Glengowan Dam; and (c) zero loadings to the Thames River from WPCP's, attainable with effluent bypassing to Lake Erie. The results of the modelling studies are presented in this paper. Key words: water quality, dissolved oxygen, flow augmentation, environmental assessment, Glengowan Dam, Thames River Basin, deterministic model, stochastic model.
Initial operating experiences of a nutrient removal process (Modified Bardenpho) at Kelowna, British Columbia
Authors: Oldham W. K. , Stevens G. M.
Published: January 2010

A new wastewater treatment plant that utilizes the “Modified Bardenpho” process for nutrient removal has recently been commissioned in Kelowna, B.C. The 260 L/s facility (130 L/s in each of two parallel modules) has been operating at full design flow through one module for over 6 months.Two months of operating time was required to establish the nitrification–denitrification capabilities and to build up the phosphorus release–uptake mechanism in the biomass. Subsequent to that start-up period, the process has been capable of producing an effluent containing less than 5 mg/L total nitrogen and less than 0.3 mg/L orthophosphate when the influent sewage has contained some 30 mg/L of nitrogen and 6 mg/L of phosphorus. Key words: phosphorus removal, nitrogen removal, biological waste treatment, advanced waste treatment.
Repair and evaluation of a damaged truss bridge—Lewes, Yukon River
Authors: Beauchamp J. C. , Chan M. Y. T. , Pion R. H.
Published: January 2010

The Yukon River Bridge, a two-span truss bridge on the Alaska Highway, was damaged by a traffic accident in January 1982. This paper describes the actions taken to repair and strengthen the damaged structure. Highlighted in the paper is the repair of a fractured bottom chord, which opened up 2 in. (50.8 mm) after the accident. Field measurements of member forces taken during the repair operation and at proof load tests carried out after the repairs are presented. Structural responses obtained from theoretical computer analyses are compared with the field-measured values. Results of physical and chemical laboratory tests performed on samples of the bridge steel are reported, and lessons learned from the project are discussed. Key words: truss, bridge, steel, concrete, repair, strengthening, brittleness, stress, measurement, jacking, restoration, fracture, traffic, accident, damage.
Cold climate facultative lagoons
Authors: Tilsworth Timothy , Smith Daniel W.
Published: January 2010

Facultative lagoons are of great importance to small communities of Alaska and northern Canada. Severe climatological conditions along with seriously impeded economic development have dramatically reduced the viable alternatives available for wastewater treatment. Design engineers face almost formidable constraints when attempting to produce “secondary” effluents for these communities. Because of permafrost, the absence of electrical power, average annual temperatures as low as −12 °C (10°F), the lack of skilled manpower, and other operating restrictions, lagoons can be of strategic importance to water quality protection in these locations.The use of “southern” technology may not be applicable under arctic–subarctic conditions and even if it is applicable it must be used with considerable reservation. This paper reviews the use of facultative lagoons in cold climate areas and addresses issues of design parameters, economics, and the system's ability to meet wastewater treatment regulations and water quality standards. Consideration of factors influenced by temperature including psychrophilic organisms and ice cover are reviewed in this discussion along with a “common sense” approach to design. Key words: lagoons, cold, permafrost, wastewater, design, BOD, ponds, facultative, algae, northern, ice, anaerobic, kinetics, arctic.
Design storms for urban drainage design
Authors: Marsalek J. , Watt W. E.
Published: January 2010

The design storm concept is well established in Canadian urban drainage practice, but appropriate use is hindered by an incomplete definition of design storms and their applications. To remedy this situation, it is recommended that design storms be described for various regions and a wide range of durations and return periods; these storms should be based on local Atmospheric Environment Service (AES) rainfall data, given for both the rational method and hydrograph model applications, and supplemented by specifications of the computational procedure and normal antecedent conditions. Such design storms would produce peak flows of approximately the same return period as that of the design flow. None of the existing design storms has all these features but an acceptable set of design storms could be developed using existing Canadian data. Key words: design storms, urban drainage, stormwater, hydrological design, precipitation, runoff computations.
River mixing—A state-of-the-art report
Authors: Elhadi N. , Harrington A. , Hill I. , Lau Y. L. , Krishnappan B. G.
Published: January 2010

This report is intended as a reference for practising engineers. A description of the various physical processes involved in the spreading of a substance in river flows as well as the mathematical formulation of these processes is given. These processes are combined in the mass balance equation to describe the mixing of substances released into rivers. The difficulties of solving three-dimensional mixing problems for real river situations are discussed. The simplification of the equation into two dimensions using depth averaging and the introduction of the stream-tube concept are described. Analytical and numerical solutions are recommended. The conventional Fickian description of one-dimensional mixing is given, followed by the description of a model that takes into account the non-Fickian behaviour often observed. Sample problems of one-dimensional and two-dimensional mixing are solved, using the recommended procedures. The effects of ice cover on mixing are discussed and cases of nonconservative substances are described. Key words: mixing, rivers, dispersion, concentration distribution, longitudinal mixing, transverse mixing, stream-tube model.
Utilization of a microcomputer in the calculation of calcocarbonic equilibrium curves
Authors: Dubuc Y. , Desjardins R. , Brière F. , Piron D. L.
Published: January 2010

In a water treatment plant, filtered water usually has a pH lower than 6. The recommended lower limit for drinking water is 6.5. In most cases the pH is adjusted to a value slightly higher than the equilibrium pH to stabilize the water with regard to CaCO3. The Legrand–Poirier model permits the calculations of the calcocarbonic equilibrium conditions. This model is more powerful than the Langelier equation but requires long and arduous computations. Therefore, a research group at École Polytechnique de Montréal has developed a microcomputer program to compute and plot the Legrand–Poirier diagrams. This program will be put to use in the water treatment plants of the City of Laval (Québec, Canada). Key words: water treatment, drinking water, stabilization, calcocarbonic equilibrium.
Analysis and design of a rigid frame bridge with skew, curved plan geometry
Authors: Fam Adel
Published: January 2010

The paper presents a case study for the design of a two-span prestressed concrete rigid frame bridge, built as a part of a Point Diamond traffic interchange between Welland Vale Road and Highway 406 in the City of St. Catherines. The bridge deck has a 42° skew alignment and its boundaries are sharply curved to follow exactly the ramp alignment at the four corners. The requirements affecting the selection of the structural type and the detailing of components are briefly presented. The idealization of the bridge, using three-dimensional quadrilateral finite elements, and the programs used to automate the input data and to perform the analysis are described in some detail. Structural responses such as vertical deflection, longitudinal and transverse stresses, and support reactions are presented for the different loading conditions, and the critical responses unique to this type of bridge are identified. The project demonstrates the usefulness and practicality of the finite element method in freeing the designer from the limitations of simplified methods of analysis and permitting the selection of economic, functional, and aesthetic structures.
Influence de la turbulence sur la force tractrice dans les canaux rectangulaires lisses
Authors: Rohan Karol , Pilon Gérald
Published: January 2010

A specific research program was undertaken at the University of Sherbrooke in order to develop new procedures to determine the mean and the maximal shear stress found by means of velocity distribution measurements. For this purpose, the noninvasive flow measurement technique of laser velocimetry was employed.For smooth rectangular channels, a function between local velocity and local shear stress was developed, which includes nondimensional parameters such as the form factor of the cross section, the slope of the energy grade line, and the Reynolds number. This function can also be employed to estimate the value of maximal instantaneous shear stresses.
Construction of the Linn Cove Bridge
Authors: Iverson James K. , Rattray Ralph R.
Published: January 2010

The Linn Cove Bridge is a medium-span, segmental bridge that has been used to solve an unusual environmental problem on a scenic mountain highway in North Carolina. The resulting structure features curves of 76 m (250 ft) radius and 0.1 m/m superelevation. The site is quite remote and extremely rough. A number of unusual methods were used to construct the bridge. A highly adjustable form was built and performed well; a small-volume concrete-mixing truck was adapted to the project; and a stiff-leg crane was modified to be more mobile so it could be used to erect the segments. The foundations were constructed using reinforced "microshafts." Several other innovations are outlined in the paper.
Analysis and computerized model of the automatic hydraulic ram pump
Authors: Schiller E. J. , Kahangire P.
Published: January 2010

The operating characteristics of the hydram system were studied analytically, with some parameters being determined experimentally. The system efficiency, pumping capacity, pump power, and cycle duration were derived with a simple computerized model. Comparison of the model and experimental results gave good correlations for pump efficiency and pump capacity. Pump power and cycle duration were not predicted with high accuracy, but satisfactory trends were obtained. The computer model also indicated that high friction losses through the valves are undesirable and that the velocity, obtained in the drive pipe, at which the waste valve begins to close is the dominant factor controlling the hydram operation. Finally, it was demonstrated that the theoretical model could be used for hydram design, prediction of hydram performance in a planned installation, and survey of suitable sites for hydram use. Key words: computer modelling, hydram, hydraulic ram, pump, pumping, pump characteristics, renewable energy, water hammer.
Ontario Modular Bridge Analysis System
Authors: Dorton R. A. , Richardson B. S. , Fam A.
Published: January 2010

A software system, the Ontario Modular Bridge Analysis System, being developed by the Province of Ontario for the design and analysis of highway structures is described. The new Ontario Highway Bridge Design Code, an entirely limit states code, created the need for a new or drastically revised system. An outline is given of the advisability study that led to the design of an entirely modularized, data base supported system, providing the low processing costs and user convenience of single-purpose programs together with sophisticated analytical methods for nonroutine problems.The system comprises an applications subsystem and a utilities subsystem. The applications subsystem consists of 11 macro-modules, each performing a distinct task and capable of being replaced or modified without necessitating changes elsewhere in the system. The macro-modules are Input, Control, Geometry, Idealization, Load, Solution, Live Load, Combination, Resistance, Design and Detailing, and Output.The utilities subsystem consists of modules providing services to construct or facilitate the use of the applications subsystem. These include a problem-oriented language analyzer, memory and data base manager, output utilities, and mathematical utilities.The description of the system is general with more details given concerning important or original features such as methods of analysis and the specifications analyzer, which places all design code requirements in a single, readily changeable module. Key words: analysis, bridges, codes, computers, data base, design, modular systems, software, structures.
The Twelve Mile Creek bridges—Design and construction
Authors: Ramakko O. E.
Published: January 2010

The two bridges featured are precast segmental concrete box girders built by the balanced cantilever method. Crossing a hydro tailrace, this $11 million project forms a part of the new Highway 406 through St. Catharines, Ontario. Several unique features of the structures are highlighted. These features include transverse rib beams employed at each segment face to support the deck slab; flaring of the deck slabs to accommodate on and off ramps; and twisting horizontal alignment of the highway. Both bridges have a depth-to-span ratio of 1:27, which results in one of the most slender precast box girder bridges built by the balanced cantilever method. The construction phase of this project is reviewed with particular attention to the casting operation and to the erection of the segments employing a steel launching truss. Design- and construction-related problems encountered are presented and reveal that the more perplexing problems are generally those not related to the complexities of the segmental form of construction but rather to the more mundane aspects of posttensioned concrete bridge construction. Key words: precast segmental concrete box girder bridges, balanced cantilever methods, steel launching truss, short line casting bed.
Comparison of field data with theories on ice cover progression in large rivers
Authors: Michel Bernard
Published: January 2010

There are many theories pertaining to the progression of ice covers in rivers fed by frazil slush and floes but very few have been examined critically by comparing them with field data. In this paper the existing theories on dynamic ice cover progression are reviewed, an additional one is proposed, and they are classified according to the physical mechanisms that are involved. Finally, they are compared with some existing field data for large rivers. The data are extremely scarce and difficult to obtain because of the costs involved and the dangers in traveling over thin ice when the ice cover is being formed.It is usually easier to get only the critical values of parameters giving the limits of ice cover progression. In this paper, complete data were taken from the St. Lawrence River, the Beauharnois Canal, and the La Grande Rivière where the ice thicknesses along with the flow parameters have been measured.In these cases the existing data are adequate, so they could be grouped to explain the various mechanisms involved and to obtain numerical values for their quantitative determination. Key words: glaciology, river ice, ice dynamics, fluvial processes, ice hydraulics.
The Ontario bridge code—Development and implementation
Authors: Dorton R. A.
Published: January 2010

The Ontario Highway Bridge Design Code was first issued in 1979 and has since been used for the design and evaluation of most bridges in Ontario. The code is in metric SI units, written in a limit states format, and calibrated to a target safety index value of 3.5. It has produced bridges with a more consistent safety level and capable of carrying design live loads twice those previously prescribed. Feedback from users was obtained and their concerns considered in formulating the provisions of the seeond edition in 1983. New bridge codes can be written in a short time and implemented most readily within a relatively small jurisdiction having control of all highways, bridges, and vehicles. Communications between the writers and potential users are important throughout the preparation and implementation phases. It is essential that a commentary volume be issued with a code to ensure correct understanding and interpretation of new provisions. Computer programs should be available, incorporating the code technology before the use of a new code becomes mandatory. Future code needs and likely areas of new development are outlined in the paper. Key words: calibration, codes, computer systems, highway bridges, loadings, safety, structures.
Bracing for composite box girder bridges
Authors: Branco Fernando A. , Green Roger
Published: January 2010

For steel–concrete composite box girder bridges, the steelwork is generally erected first and then the concrete deck cast. During construction the girder may be subjected to a variety of construction loads. If the girder is a flexible open section, and lacks distortional or torsional stiffness, the cross section will deform or twist excessively; such difficulties with box girder construction have been reported. Bracing systems should be installed to increase the torsional and distortional stiffness of the open section during construction. A finite strip analysis of the influence of bracing systems on open section box girders is presented and compared with test results obtained using a one-quarter scale model. With the analysis, the influence of ties, distortional bracing, torsion boxes, and top chord bracing on the behaviour of torsionally open box girders is examined. Simplified design methods are also presented whereby the bracing forces and the stresses arising from the distortion of the section can be computed. Key words: bridges (box girder), bridges (steel), box beams, torsional distortion, bending distortion, bracing, construction safety.
Into the twentieth century — Two Toronto bridges
Authors: Rose Phyllis
Published: January 2010

During a single decade, two bridges were built in Toronto's Don Valley. The first, the Bloor Viaduct, designed and built between 1915 and 1918, represents a splendid example of traditional bridge building, a series of three-hinged arches on ornamental concrete piers. The Leaside Bridge, constructed in 1927, consists of a steel Warren truss, which also rests on concrete piers. The visual impact of the more ornate Bloor contrasts sharply with the plain, unadorned Leaside. Contemporary bridges more closely resemble the Leaside. Key words: Toronto bridges, Bloor Viaduct, steel arch, concrete piers, Leaside Bridge, steel Warren truss.
The mechanical properties of sea ice — A compilation of available data
Authors: Lainey Luc , Tinawi René
Published: January 2010

The mechanical properties of S2- and S3-type sea ice are reviewed. Strength and, in some cases, elastic moduli are presented for short-term loadings. The loadings considered are uniaxial tension and compression and multiaxial compression; annular tests as well as flexural and shear tests were also reported. The parameters that influence the values are also described. These are the grain diameter and orientation, loading rate, temperature, salinity, and density, as well as the size of the specimens and whether these are obtained in the field or are laboratory grown. The long-term mechanical properties are also presented. Creep laws or relaxation functions are given whenever available. The results of the compilation are presented in a tabulated form for each type of loading. A short discussion is also given for each mechanical property. Key words: sea ice mechanical properties, sea ice strength, sea ice modulus, sea ice creep, sea ice behaviour.
Turbulent wind forces on a large span roof and their representation by equivalent static loads
Authors: Davenport A. G. , Surry D.
Published: January 2010

The paper describes the measurement of the steady and fluctuating wind forces on a large span roof and their representation by equivalent static loads. The work was undertaken as part of a study for the Olympic Saddledome, Calgary, Canada, but has quite general applicability to other large span roofs. The procedure defines the shape of the structural loading in terms of simple patterns; in this case, harmonic Fourier functions were chosen. The force coefficients defining the amplitudes of these orthogonal loading patterns are each summarized by a mean coefficient [Formula: see text]; a root-mean-square fluctuating coefficient, [Formula: see text]; and a resonant magnification factor, (RMF)i. The equivalent static design pressure loading, pD(r,θ), over the roof surface is then represented by an expression[Formula: see text]in which r and θ are polar coordinates, q is the reference velocity pressure of the wind [Formula: see text], gi, is a statistical load combination factor, and μi(r,θ) is the shape of the ith pattern or function.Aerodynamic data defining these coefficients were derived from a boundary layer wind tunnel investigation, using an adaptation of the pneumatic averaging technique. As well as the distributed force coefficients, local pressure coefficients are also given. The dynamic content of the loading was found to be highly significant both on account of its magnitude, which was larger than the mean, and because of its variable distribution. Approximately one-quarter of the dynamic loading might be associated with resonance amplification. Key words: aerodynamics, arenas, design, dynamics, pressure, roofs, turbulent flow, wind loads, wind tunnel tests.
Bracing in completed composite box girder bridges
Authors: Branco F. A. , Green R.
Published: January 2010

During construction, bracing systems are included in box girders to prevent excessive distortion or twist of the sections. The influence of bracing on the deformation of composite bridges during service is examined. A linear elastic finite strip analysis was developed and results are compared with experimental studies from a model and a prototype bridge. The effectiveness of transverse web stiffeners and distortional bracing in preventing distortional stresses is studied. Transverse web stiffeners are effective in resisting distortion of completed girders, and distortional bracing is not essential for stiffened girders. For unstiffened girders, bracing is essential if additional longitudinal stresses due to distortion are not included in design. Interconnecting bracing between boxes is found to be effective in reducing transverse slab moments. Key words: bridges (box girder), bridges (composite), distortion, load distribution, web stiffening, bracing.
Ice action on Nanisivik wharf, winter 1979–1980
Authors: Frederking R. , Nakawo M.
Published: January 2010

During the period December 1979 to June 1980, five visits were made to observe and measure ice behaviour around the wharf at Nanisivik, on Baffin Island. The measurements included ice thickness, temperature, salinity, and density, as well as horizontal movements of the ice cover. In March 1980, additional measurements and observations were made of tides, rotations of the ice sheet, and grain structure of the ice. A model for the formation of an active zone of ice between the wharf and the adjacent ice cover has been proposed, based on the observed evolution of ice conditions and internal structure of the active zone. Horizontal growth of the active zone displaces the adjacent ice cover away from the wharf, and in so doing, generates ice pressures estimated at 69 kPa on the wharf. Key words: ice forces, wharves, ice behaviour, ice properties.
Resistance factors for laterally unsupported steel beams and biaxially loaded steel beam columns
Authors: Baker Karen A. , Kennedy D. J. Laurie
Published: January 2010

Data from 30 tests conducted on laterally unsupported steel beams, and 148 tests on biaxially loaded steel beam columns conducted by others are statistically analyzed to determine resistance factors appropriate for use with the design equations given in CSA Standard CAN3-S16.1-M84 (Steel structures for buildings—limit states design). The general value of 0.90 currently given in that standard for the resistance factor is shown to be conservative by 1 –6% for both laterally unsupported beams and biaxially loaded beam columns. Key words: beam columns, beams, biaxially loaded, laterally unsupported, limit states design, resistance factors, steel.
Investigation of prestressed concrete box beams of an elevated expressway
Authors: Tork Andres
Published: January 2010

The object of this paper is to share the experience gained from an investigation of prestressed concrete box beams of the elevated roadway of the F. G. Gardiner Expressway in Toronto, 16 years after construction. The 18–30 m long, simply supported beams, which are either pretensioned or posttensioned with prestressing strands, are covered by concrete topping and asphalt. Methods of investigation include coring, chloride-content tests, and power chipping of soffit areas. Rusted reinforcing steel, rusted prestressing strands, and delaminated or spalled concrete were found at transverse joints and at beam soffits. Concrete damage due to bird droppings, as well as a beam with nearly 60% strand loss, were discovered. Causes for deterioration are discussed and proposed repair methods are described.
Strength of spaced timber columns
Authors: Van Dyer D. B. , Malhotra S. K.
Published: January 2010

A rational procedure for determining the strength of spaced timber columns is presented. The effect of interlayer slip, characteristic of layered systems with nonrigid connections, is considered in the theoretical development. A good agreement is observed between the theoretical predictions and experimental results of some 110 spaced columns. The effect of number of spacer blocks on column strength is investigated, and efficiency of various types of spaced columns is compared, first with respect to each other and then with respect to equivalent solid and layered systems. Finally, the theory is compared with design specifications given by CSA Standard CAN3-086-M80, "Code for engineering design in wood." Key words: bolts, buckling, columns (supports), design practice, efficiency, nails, nonrigid connection, spaced columns, split ring connectors, strength, structural engineering, tests, theory, timber construction.
A unified degree-day method for river ice cover thickness simulation
Authors: Shen Hung Tao , Yapa Poojitha D.
Published: January 2010

A unified degree-day method for simulating the thermal growth, decay, and breakup of river ice covers is developed and applied to ice covers in the St. Lawrence River between Lake Ontario and Cornwall, Ontario. In the simulation model, the variation of the ice cover thickness is related to the ambient air temperature by the formula[Formula: see text]in which h = ice cover thickness; h0 = initial ice cover thickness; S = degree-days of freezing since the formation of the ice cover; t = number of days since the formation of the initial ice cover; and α, β, θ = empirical coefficients. Key words: breakup, degree-day method, ice cover thickness, river, simulation, St. Lawrence River.
Seismic base isolation for steel structures
Authors: Stiemer S. F. , Barwig B. B.
Published: January 2010

Base isolation is a strategy for a design of buildings in areas where seismic loads govern. It enables the reduction of earthquake excitation to an acceptable level, without an increase of structural acceleration. This paper presents the results of the experimental investigations of various schemes of first-storey designs for steel buildings with base isolation.A scaled-down steel frame building was used for the shaking table tests, which were conducted in the Earthquake Simulator Laboratory of the University of British Columbia. The base-storey design was altered while the dynamic response of the frame was recorded. The base isolation consisted of steel roller bearings with parallel steel yield rings, to limit excessive displacements and provide wind restraint.The proposed base storey is substantially different from conventional solutions. The variation in the base-storey design was aimed at the elimination of the blind base storey or double foundation in order to increase the economy of the base-isolation system. The experimental tests showed suitable design approaches, and analytical studies to optimize them will follow.It was verified that uncoupling of buildings from the earthquake ground motion is relatively simple to achieve. Certain restraint is required to resist wind and other horizontal loads. This is usually achieved by mechanical fuses or energy absorbers. A solid state energy absorber was used in the described tests. Key words: base-isolation system for buildings, earthquake-resistant steel structures, experimental investigations, retrofit system.
Gradation, design, and cost consideration in blending aggregates for asphaltic concrete pavements
Authors: Easa Said M.
Published: January 2010

This paper presents an analytic (algorithmic) method for determining the optimum proportions of aggregates that satisfy specific gradation, design, and cost requirements of the blend. The gradation requirements include the specification limits and mean deviation from the midpoint of specifications limits. The design requirements include fineness modulus, plasticity index, and specific gravity. The optimum proportions may correspond to minimum mean deviation or minimum cost. In addition to providing the optimum solutions, the method provides the entire feasible region of proportions that may be useful if adjustments of proportions are deemed necessary.The paper first reviews existing aggregate blending methods, classifies them, and describes how the proposed method fits into that classification system. The method is then described along with its graphical interpretation. The method may be regarded as a simulation process and as such is not subjected to any type of constraints. Application of the method to a numerical aggregate blending problem was made to illustrate its use.While existing methods consider minimizing mean deviation (with no consideration of cost) or minimizing cost (with no consideration of mean deviation) the proposed method considers both mean deviation and cost as well as the physical properties. Other advantages of the method include adaptability to linear or stepwise cost functions of aggregates, automatic elimination of negative solutions, and provision for different weights (importance levels) of sieve specifications. Key words: blending, aggregate proportions, cost, mean deviation, gradation, specific gravity, plasticity index, fineness modulus, asphaltic concrete.
Effect of interface gap on load–slip characteristics of timber joints fabricated with multiple nails
Authors: Malhotra S. K. , Thomas B.
Published: January 2010

An experimental program, exploratory in nature, has been carried out to investigate the effect of interface gap on the load–slip behaviour of joints fabricated with multiple nails. In total, 320 joint specimens have been tested. Modification factors are developed to account for the effects of number of nails and interface gap on the overall load-carrying capacity of joints with multiple nails. The current practice for the design of nailed joints is that a joint fastened together with multiple nails in a row, regardless of the interface characteristics of that joint, carries lateral load equal to the product of the lateral-load capacity of the corresponding joint with a single nail and the number of nails in a row of the joint. The findings of this investigation indicate this practice to be somewhat of an overestimation of the overall capacity of the joint. Key words: design, interface gap, interface friction, joint slip, loads (forces), modification factors, multiple fasteners, nailed joints, stiffness, structural engineering, tests, timber construction.
Impact of alternative housing standards on stormwater management
Authors: McBean Edward A. , Ellis Hugh , Mulamoottil George
Published: January 2010

The impact of alternative subdivision standards on the design of stormwater management systems is explored with a view toward quantifying such impacts. The combined drainage flow (piped plus overland) for reduced standards (e.g. smaller lot sizes, road widths) for the ease study analyzed is shown to be comparable to the flow emanating from a conventional design standards system, in terms of both peak flow and total volume, and the quality of the drainage water from the reduced standards system is acceptable. A comparison of stormwater-related cost savings shows that the "per lot" costs for the reduced standards system are approximately 50–70% of those associated with the conventional designs. Key words: stormwater management, subdivision design, storm sewers.
Preliminary design of standard CPCI prestressed bridge girders by linear programming
Authors: Fereig Sami M.
Published: January 2010

The design of prestressed concrete bridges using standard CPCI (Canadian Prestressed Concrete Institute) girders is generally done by trial and error, requiring extensive computation. This study will use a linear programming mathematical model to establish preliminary design charts for such cases and to obtain the required prestressing force after losses for a given CPCI bridge interior girder with different spans and spacings. The bridge is designed to carry the MS200-77 loading, and the design conforms with the Canadian Standards Association CAN3-S6-M79 for design of highway bridges. The bridge considered is single-span, with a cast in situ concrete deck acting compositely with the prestressed girders under live load. The linear programming model is also used to determine the design criteria that will control the design for the cases investigated, and to perform the parametric study to evaluate the effect of variations in deck thickness, girder concrete strength, and prestressing losses on the value of the required prestressing force. Key words: bending moment, concrete, girders, highway bridges, linear programming, load, prestressing, span.
Charts for water hammer in pipelines resulting from valve closure from full opening only
Authors: Karney Bryan W. , Ruus Eugen
Published: January 2010

Maximum pressure head rises, which result from total closure of the valve from an initially fully open position, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Uniform, equal-percentage, optimum, and parabolic closure arrangements are analysed. Basic parameters such as pipeline constant, relative closure time, and pipe wall friction are considered with closures from full valve opening only. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe with good accuracy for the closure arrangements considered. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the parabolic closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Uniform closure produces pressure head rise that usually lies between those produced by the parabolic and the equal-percentage closure arrangements, except for the range of low pressure head rise combined with low or zero friction, where the rise due to uniform closure approaches that produced by optimum closure.
Analysis of concrete box beams using small computer capacity
Authors: Maisel B. I.
Published: January 2010

Following the generalized coordinate method of Vlasov, simple beam theory has been extended to treat torsional, distortional, and shear lag effects in straight, thin-walled box beams of uniform section. Single-cell or multicell sections with side cantilevers can be analysed, and the structure can be single-span or continuous. An example suitable for use in design is given, and all the calculations have been performed on a nonprogrammable hand calculator. The method is suitable for quick preliminary design and for reassessment of load capacity of a bridge. Comparisons are made with the results of finite strip computations. It is expected that when the method of hand analysis is programmed, computing times will be so short that interactive design procedures will become feasible, making it possible to develop relatively simple design rules which consider adequately the types of structural action specific to box beams. A physical understanding of box beam behaviour is facilitated by the use of the theory given here. As the elastic solution developed satisfies equilibrium, it can be factored to give a lower bound to the collapse load, for use in limit state design. Key words: analysis, box beams, bridges, distortion, interactive design, microcomputers, shear lag, torsion, warping.
Caractérisation des propriétés dispersives d'un milieu poreux par mesures expérimentales de la migration d'un traceur salin
Authors: Marche Claude , Leclerc Guy , Gaudette Michel , Delmas Daniel
Published: January 2010

Groundwater quality management requires a good understanding of the contaminant migration phenomena within the porous media. A horizontal experimental tank (gross area of 63 m2) was built at Ecole Polytechnique de Montréal. An automatic data acquisition system, developed around a Timex-Sinclair ZX81 microcomputer, monitors, through 30 probes located in observation wells, the migration of a saline tracer. The dispersive properties of a limestone aggregate are derived from the spatial and temporal distribution of the tracer concentration. Key words: groundwater, quality, dispersion coefficient, automatic data acquisition, experimental tank, laboratory model, microcomputer.
A general expression for basin lag time
Authors: Watt W. Edgar , Chow K. C. Ander
Published: January 2010

Basin lag time is an important variable in the calculation of peak discharge resulting from a specified precipitation input. For the case of ungauged basins, the lag time must be estimated, normally from one or more expressions relating lag time to basin physical characteristics. A number of such expressions exist but each was developed for a particular range of basin size and geographic region. To overcome the problem of using an expression that may not be appropriate, a tentative general expression for basin lag time has been developed using data from basins representative of many regions in North America and ranging in area from 0.5 ha to 5840 km2. The tentative expression has only one basin characteristic, basin length divided by the square root of basin slope, [Formula: see text], and applies to natural basins with minimal effective lake and swamp storage. When more data become available, the expression will be modified to include the effects of urban development and significant storage. Key words: lag time, peak discharge, prediction equation, ungauged basins.
Approximate analysis and optimization of stiffened tied arch bridges
Authors: McNeely D. K. , Sneep J. S. , Smith K. N.
Published: January 2010

The stiffened tied arch bridge has a tie consisting of a stiff flexural member, which tends to distribute live loads uniformly over the arch. Various approximate methods for analyzing this system are presented, including Maillart's method, a simplification of that procedure, the single-redundancy method, and an elastic foundation approach. Comparisons are made with a computer analysis to determine the accuracy of each procedure. Increased familiarity with this structure should lead to more frequent consideration of this type of bridge by designers.An optimization study was carried out for spans in the range of 50–150 m. This investigation indicated that a girder-to-arch stiffness ratio of about 9 is desirable. Key words: analysis, arch, bridge, optimization, stiffened, structure, tie.
Water supply and waste disposal on permanent snowfields
Authors: Reed S. C. , Bouzoun J. R. , Tobiasson W. T.
Published: January 2010

The snow and glacial ice on permanent snowfields must serve as both the water source and the receptacle for wastes for any human habitation. In addition, the snow also serves as the support media for any structural foundations and hence the thermal aspects of water supply and waste disposal can be critical. Most activity has occurred on the ice caps of Greenland and Antarctica and has ranged from small transient field parties to large permanent facilities in continuous use for over 25 years. Novel procedures to insure the reliable production of good quality water are described as well as the recommended criteria for water quantity depending on the size and duration of the activity. The various methods of wastewater disposal that have been used at temporary camps and permanent stations are described along with the results from studies that defined the fate of the wastewater following its discharge to the snow. Such definition is important to insure protection of the water supply as well as the thermal integrity of any structural foundation. Key words: water supply, water quality, sewage waste disposal, ice cap, glaciers, snowfields.
Lateral load analysis of three-dimensional flat plate structures
Authors: Chislett M. , Morris Glenn
Published: January 2010

A procedure is described for performing a linear structural analysis of laterally loaded three-dimensional flat plate structures, with or without shear walls. The structure is assumed to be comprised of column, shear wall, and floor plate elements. To minimize storage requirements for the computer program that performs the analysis, the flat plate floors are assumed to act as rigid in-plane diaphragms. The shear walls are modeled as columns for in-plane bending and as wide beams for out-of-plane bending.Dimensionless stiffness matrices for floor plate elements with four different column width – span ratios have been evaluated using a finite element analysis and incorporated into the structural analysis computer program. Lagrange interpolation is used to evaluate the stiffness matrices for floor plate elements with any specified column width – span ratio. In assembling the structure stiffness matrix, the floor plate nodes along the boundaries between floor panels are condensed off.Examples are presented to demonstrate the accuracy and economy of the analysis procedure and to illustrate the influence of column width – span ratio and plate width on the behavior of the structure.The procedure is the first phase in the development of an iterative analysis procedure that will model the nonlinear behavior of the flat plate structures due to cracking at the column–plate boundary. Key words: flat plate, structural analysis, slab, lateral load analysis.
Strength analysis of RHS double chord joints with separated chords
Authors: Korol R. M. , Mitri H. S.
Published: January 2010

A plastic failure model that is based on the yield line theory of plates is developed to provide a means for predicting the plastic strength of double chord RHS K-joints with separated chords. The model accounts for both localized bending of the chord face and shearing of its inner and outer walls in the gap between the mated diagonals.The results of a series of 24 tests conducted on RHS twin shear beams are reported. Predictions of joint strength were compared with experimental results and were found to be generally in good agreement for both the RHS twin shear beams and isolated K-joint specimens of square hollow section from previous work. A study on the effect that varying the geometrical properties of the joint has on its strength is also presented. Key words: experiments, K-joints, mechanism, plastic analysis, rectangular hollow sections, steel, yield lines.
Comparison of MOBED and HEC-6 river flow models
Authors: Krishnappan B. G.
Published: January 2010

The MOBED and HEC-6 models of river flow were compared in this study. The comparison consisted of two steps. In step one, the major differences between the models were identified by examining the theoretical base of each model. In step two, the predictive capabilities of the models were compared by applying the models to identical data sets. The data set comes from the South Saskatchewan River reach below Gardiner Dam and relates to the degradation process that has taken place since the creation of Lake Diefenbaker. Comparison of model predictions with measurements reveals that MOBED has predictive capability superior to that of HEC-6 and that use of HEC-6 as a predictive tool requires an extensive model calibration by the adjustment of Manning's 'n' and the moveable bed width. Key words: computers, models, sediment transport, river hydraulics erosion.
Estimation of wastewater treatment costs: Evaluation of the CAPDET model for Canadian conditions
Authors: Pineau M. , Côté P. , Villeneuve J. P.
Published: January 2010

CAPDET is a computer program for estimating construction and operation costs of wastewater treatment plants. A validation study of the model was carried out in order to assess its capabilities for predicting these costs for Canadian conditions. The validation was performed using data from existing full-scale facilities located in Ontario, Québec, and other provinces. The validation study identifies problems in applying the model to Canadian conditions and formulates precise recommendations to account for them. Key results of the validation study were that construction costs can be predicted by the model to within ±20% of the actual costs and operation and maintenance costs to within ±30%. Key words: wastewater treatment plants, construction costs, operation and maintenance costs, CAPDET, computer program.
Mixing coefficient for ice-covered and free-surface flows
Authors: Lau Y. L.
Published: January 2010

Dispersion experiments were conducted in four river reaches under both open-water and ice-covered flow conditions. The data were used to obtain the transverse mixing coefficient and to investigate which dimensionless mixing coefficient should be used for ice-covered flows. The results also demonstrate that the sinuosity of a river reach affects the value of the mixing coefficient and can thus be used to guide the selection of mixing coefficient for natural streams.
Fire protection for northern communities
Authors: Heinke G. W. , Christensen V. , Hipperson L. , Bowering E. J.
Published: January 2010

Small, isolated communities present special problems for fire protection. Many communities in northern Canada and Alaska have less than 1000 people. They are isolated, have no tax base, and have high costs. Most cannot afford to provide any type of fire protection. In the Canadian Territories, grant money for public services, including fire protection, are provided by the government whereas in Alaska each community is left to its own resources.This paper presents a review of the existing situation in northern regions as of 1981 and compares, among similar communities, their fire loss records in light of their fire protection efforts. Recommendations for fire protection systems in these communities are presented. Key words: fire protection, northern communities, public services, water supply, Alaska, Northwest Territories, Yukon, Greenland.