bluuebunny/crossref_metadata_2025 huggingface dataset:
Problems and possibilities in urban drainage
Authors: Waller D. H.
Published: January 2010

Urban drainage problems in Canada will grow with increasing urbanization. In developing areas problems are related to increased volumes and rates of surface runoff; problems in developed areas are overloaded sewerage systems, combined sewer overflows, and urban surface water pollution. Research and demonstration programs in Canada and the United States are examining potential solutions to these problems. Rate and volume of storm water may be controlled by diversion of unwanted water or by storage. Controls on quantity include source controls, combined sewerage system modifications and operational changes, and treatment methods. Urban drainage models can simulate system behaviour and evaluate performance of alternative solutions. The three most generally useful models are STORM, Storm Water Management Model (SWMM), and the Illinois Urban Drainage Area Simulator (ILLUDAS). Development and application of models may be the most significant single result of urban drainage research and demonstration activities.
Commentary on the basic philosophy and recent development of safety margins
Authors: Knoll Franz
Published: January 2010

The principal effects influencing safety margins are recapitulated. Human errors are found to be the major source of structural failure. A revised format for safety margins is proposed, using partial factors, one of which should represent the effects of human errors. It should be used as a basic safety margin, reflecting the fact of the importance of human errors.Recent changes in design rules as set forth in the National Building Code of Canada 1975, are discussed and criticized for having reduced effective safety margins to unacceptably low levels. Examples are given to illustrate possible consequences of the use of such low safety margins.
Selection of optimal policies for airport projects
Authors: Sargious Michel A. , Salinas J. J.
Published: January 2010

This study describes a procedure for the evaluation and choice of new airport projects (or upgrading of existing ones) when different alternatives are proposed for each airport component and when a budget is set for the whole project. Some major objectives which are important to the different groups concerned with airports are identified and considered in the analysis. A multi-objective investment planning model is set up and a computer program is developed by the authors to carry out the analysis. The program is applied to rank the various airport proposals according to their overall effectiveness in satisfying the objectives. Each airport proposal, in this context, consists of a combination of different alternatives for the various components. No more than one alternative for each component is included in one proposal. The effectiveness of an alternative with regard to a certain objective is a measure of the degree to which the objective is satisfied by the alternative.Since there is usually a budget assigned to each public project, such as an airport, the capital costs of the feasible proposals should fall within the budget limit. Proposals exceeding the budget are considered infeasible and are removed from the analysis by the program at an early stage.
A combined snowmelt and rainfall runoff model
Authors: Quick Michael C. , Pipes Anthony
Published: January 2010

An outline description is given of the University of British Columbia (U.B.C.) watershed and flow models, which are a set of computer programs for the calculation of hydrologic behaviour of watershed and river systems. The U.B.C. watershed model calculates snowmelt and rain runoff from meteorological data for mountainous watersheds. The model can be operated continuously for any number of years without reinitialization. The watershed model can be interfaced with the U.B.C. flow model which routes and combines the flows from a complex network of watersheds through downstream channels, lakes, or reservoirs.A revised temperature index for the calculation of snowmelt is presented and illustrated. In addition to using the mean daily air temperature, use is made of the diurnal temperature range to describe additional radiant energy input and the minimum temperature is used to approximate dewpoint and vapour exchange.The enhanced watershed response resulting from high intensity rainfall is examined and it is shown that this enhanced watershed response can be described by one additional parameter which modifies the normal watershed calibration. This additional parameter changes the normal infiltration behaviour of a particular watershed by a certain percentage, and, is found to be a stable parameter capable of describing a range of high intensity rain events.Application of the watershed and flow models for streamflow forecasting and planning studies are described. An outline is given of operational forecasting for the Fraser River system and of planning studies on the McGregor River. In the study of the McGregor River, streamflows were calculated for a 12 year period from meteorological data. Comparison with observed monthly flows showed a correlation coefficient of 0.96.The computer programs and documentation are available from the authors.
Mathematical modelling for optimizing bridge costs
Authors: Sargious Michel , Badawy Hammouda
Published: January 2010

Mathematical modelling can be used to obtain girder spacings and spans which will optimize the costs of multi-span concrete bridges needed for elevated stretches of highways or mass transit structures.The total cost is expressed as a function (the objective function) of the main variables, namely, main girder spacings and spans, and a set of cost coefficients. Practical requirements impose certain constraints on the choice of the variables. These constraints are respected in the optimization process.In the development of the objective function, empirical equations are needed to express the deck slab thickness, the depth of main girders, and the pier dimensions in terms of the variables.An example is solved to illustrate the method, using a non-linear programming technique called ‘SUMT’.
Design charts for reinforced concrete L-sections
Authors: Tadros Maher K.
Published: January 2010

The object of this paper is to present charts for the ultimate strength design of L-sections subjected to combined normal force and bending. The method of derivation of these charts is briefly described. It is general and applicable to other odd-shaped sections. It also conforms to the basic assumptions adopted in the CSA Standard A 23.3-1973. The charts can be used either for the determination of the dimensions of the section or for the check of its capacity.
A computer-aided snowmelt model for augmenting winter streamflow simulation in a southern Ontario drainage basin
Authors: Logan L. A.
Published: January 2010

A lumped-parameter mathematical model is formulated to represent the physical processes of the accumulating and melting snowpack within a drainage basin. Common theoretical descriptions of the processes represent snow accumulation and melt at a point, but computer-aided procedures facilitate spatial distribution of the model inputs and thus provide for a digital simulation of the basin-wide snowpack condition and melt with time. The model is treated on the basis of the energy flux and mass transfer processes relating to the average snowpack, across the snowpack–atmosphere and snowpack – ground surface interfaces. An awareness of the likely lack of the extensive meteorological data usually required for proper application of such models, necessitates reliance on a number of literature-cited and locally derived empirical snowmelt relationships in order to ensure a practical and viable model. Thus, auxiliary computer subroutines are formulated to provide for applicable options, depending on the availability of real-time data. The purpose of the snowmelt model is to serve as a monitor of net basin input, complementing an overall comprehensive integrated hydrologic system model for use in streamflow simulation. The model is calibrated and tested with real-time data in a Ministry of the Environment-IHD Representative Drainage Basin in southern Ontario. Its applicability in estimating maximum flood flows during spring runoff periods is demonstrated by imposing meteorological conditions favourable for continuous melting upon maximum snowpack storage conditions.
Peak runoff simulation in a subarctic region
Authors: Penel J. , Kung T.
Published: January 2010

Due to the lack of stream guaging stations, a peak flow simulation based on physical and meteorological parameters was established for the area along the proposed Mackenzie Valley Highway between Fort Good Hope and the Dempster Highway.Calculations based on snowmelt and rain-on-snow runoff were developed, as it was found that the snowmelt of May or early June gave the yearly spring peak discharge.Due to the gap in existing flow data, a unit hydrograph method was developed to generate additional yearly spring peak discharges. Altogether, hydrographs from four gauged watersheds of similar physical conditions with size ranging from 250 to 8 200 mi2 (648 to 21 240 km2) were used. In total, 46 yearly peak flows were generated.A regression equation of peak discharge computation was derived, using different hydrological and meteorological parameters. It was found that the most significant factors were the drainage basin area, the lake areas in the drainage basin, the water equivalent of the snow on the ground prior to melt, the rainfall in the period close to peak discharges, and the duration of snowmelt.The simulation was calibrated for drainage basins between 100 and 10 000 mi2 (250 to 25 000 km2).
Effects of altering streambed material size on a specific measure of biological diversity
Authors: Chisholm P. S. , Ayers H. D. , Dickinson W. T. , Macnab I. D.
Published: January 2010

A study of the relationship between hydraulic characteristics of streams and selected aquatic animal populations was undertaken in the Blue Springs Creek. The Blue Springs Creek is unregulated, free of evidence of pollution, and is an International Hydrologic Decade Representative Basin.The study included two phases of investigation. The preliminary phase involved the collection of field data on aquatic animal populations and hydraulic characteristics at selected stream sampling locations. These data were analyzed to determine the influence of specific hydraulic characteristics upon the animal populations sampled. It was found that the average size (D50) of streambed material has an important influence on the animal populations studied. It was also concluded that the animal populations sampled were not significantly dependent upon values of Reynolds Number, Froude Number, temperature, relative roughness, and average velocity of flow determined from study data.These preliminary results were tested during the second phase of the study. Data for the tests were obtained by altering streambed material size at selected sampling locations. The tests showed that an increase in average size of streambed material resulted in an increase in biological diversity index at a point. Conversely a decrease in the biological diversity index at a point resulted from a decrease in the average size of streambed material.
A laboratory investigation for potential durability of ready-mixed concrete retempered for air content and workability
Authors: Langan B. W. , Ward M. A.
Published: January 2010

The effects of agitation and retempering on some properties of fresh and hardened concrete are considered.Data are presented on the influence of agitation and retempering with an air-entraining agent on the workability, compressive strength, and air void system in hardened concrete.The results indicate that although agitation reduces air content and increases the spacing factor, the original parameters can be regained by proper retempering. It is shown that any loss in compressive strength due to retempering is accompanied by an increase in potential durability due to the improvement of the air void system.
A simulation model for screening a system of reservoirs for environmental impact
Authors: Hodgins D. B. , Wisner P. E. , McBean E. A.
Published: January 2010

Analysis of the potential impact of development alternatives is becoming very complex with the increasing number of constraints, many of them environmental, being imposed. As well, restricted planning budgets require that a rapid identification be made of the most promising alternatives to avoid unnecessary expenditures. A screening model to quickly isolate the most promising alternatives is thus becoming of considerable importance.A computer model that satisfies these concerns in applications involving a series of reservoirs is described in the paper. The model, with both hydrologic and water quality components, simulates and thereby indicates probable changes in downstream flows, reservoir surface fluctuations, and temperature and dissolved oxygen changes in the reservoirs and streams. Through easily adjusted operating policies, reservoir sizes, etc., the model can rapidly determine the potential impact of alternative possible developments. This information is then available to biologists, wildlife, forestry, and social disciplines as an aid in their determination of the environmental impact assessments.A case study application of the model that reflects eastern Canadian conditions is described.
Maximum surges in simple surge tanks
Authors: Ruus Eugen , El-Fitiany Farouk A.
Published: January 2010

Maximum upsurges and downsurges in simple surge tanks, resulting from linear decrease or increase in turbine discharge, gate opening, or power output are calculated in turn for simple surge tanks. Tunnel friction and velocity head are considered. The results are plotted in non-dimensional form against conduit friction and the time of closure or opening. In general, both friction and the time of closure or opening reduce the upsurge and downsurge substantially.
An example of excess urban water consumption
Authors: Gysi Marshall , Lamb Garry
Published: January 2010

A study of urban water consumption in the prairie cities is being undertaken to determine what effect metering or pricing policies can have on summer and winter consumption, and eventually on the long run benefits and costs of supply. Of particular interest is the comparison of consumption patterns in Calgary and Edmonton, the two 'twin' cities of Alberta. These two cities are very similar in size, industrial–residential mix, and climate, but Calgary uses more than twice as much water in the residential sector, where over 80% of the customers are unmetered. Initial analysis of the data indicates that the increased consumption is due mainly to the difference in pricing policies used by the two cities.
Shear strength of uniformly loaded dimension lumber
Authors: Barrett J. D. , Foschi R. O.
Published: January 2010

The shear strength of dimension lumber is studied considering both the case of straight-grained, clear material and that where the strength is controlled by the rapid propagation of an existing crack such as an end split. Shear strength in the case of clear material is studied by using a size effect model based on a weakest link approach to fracture. In the case of end splits, the strength of the member is studied by using concepts of linear elastic fracture mechanics. Methods are given for developing allowable stresses in both cases. Considering uniformly distributed loads on which current span tables for design are based, maximum tolerated lengths for end splits are derived.
Design effectiveness of wind tunnel studies for buildings of intermediate height
Authors: Surry David , Kitchen Robert B. , Davenport Alan G.
Published: January 2010

The components of a comprehensive model study involving both meteorological and wind tunnel investigations are discussed. An application of the procedures is illustrated by a case study involving a building of intermediate height and unusual geometry. The effectiveness of the wind tunnel study is presented in terms of comparisons of the resulting predicted loads with those derived from building codes, and in terms of the improved knowledge of wind action available to the designer.
Strengthening of slender hollow steel columns by filling with concrete
Authors: Ghosh Ram S.
Published: January 2010

The long hollow steel columns that support the roof of the oil storage tanks at Lennox generating station required strengthening to resist bending moments in addition to axial load. The results of a theoretical analysis indicated that pumping these columns full of concrete would provide the necessary increased capacity. However, present standards ignore the stiffening effect of concrete for columns where the slenderness ratio is high. Also, there are no test data available to confirm the theoretical analysis. Therefore, tests were conducted on two 47 ft (14 m) long, 13 in. (33 cm) diameter pipe columns, one empty and the other filled with concrete. The results of these tests confirmed that the concrete significantly increased the load and moment capacity of the columns.
Mechanism of shear transfer in reinforced concrete beams
Authors: Smith K. N. , Fereig S. M.
Published: January 2010

The mechanism of shear transfer in reinforced concrete beams with short shear spans is investigated with a view to defining the relative contribution of various component actions such as interface shear transfer across the characteristic inclined crack in such members, shear transferred by the uncracked compression zone, dowel action by the longitudinal tension reinforcement, and the contribution of the web reinforcement. The members tested and analyzed have a shear span to depth ratio of 1.5 and were loaded in the common framing situation involving shear on the sides of the members.For the beams either with horizontal web reinforcement or without any web reinforcement the distribution of internal forces was similar, with interface shear transfer, dowel action, and shear carried by the compression zone contributing to the capacity. In the case of members for which vertical web reinforcement was provided, interface shear transfer and dowel action were decreased to comparatively small component actions in the system. Acquisition of extensive measurement data and analysis of the behaviour history through various stages of loading permit the mechanism of shear transfer to be quantitatively defined.
Représentation stochastique des dommages dans les plaines inondables
Authors: Rousselle Jean , El-Jabi Nassir
Published: January 2010

The development of river basins subject to inundation requires a proper method of estimating possible damage resulting from a flood with a given return period.In the present study, a distribution function is developed, with the capability of providing an acceptable estimation of possible damage which may be incurred during a known flood.Based on the theory of extreme values in stochastic processes, a distribution function for the damage suffered is derived, assuming that the values of the extremes of exceedances are independant and identically distributed in the time interval (0, t] for a given year and season.
The basis for load and resistance factor design criteria of steel building structures
Authors: Galambos T. V. , Ravindra M. K.
Published: January 2010

This paper will detail the assumptions, the first-order probabilistic basis, the calibration, and the proposed format of load and resistance factor design (LFRD) criteria for steel building structures. Specifically, the paper will concern itself with the background and the choice of the particular first-order model, with the data bases used in evaluating the loading and the resistance functions, with the calibration procedures, and with the final selection of the load and resistance factors. The method will be illustrated by the examples of beams and columns under dead and live loading. The paper will conclude with a brief review of the research work done in connection with the development of LRFD criteria for steel building structures.
Unequal width connections of square hollow sections in Vierendeel trusses
Authors: Korol R. M. , El-Zanaty M. , Brady F. J.
Published: January 2010

This paper presents the results attained in an extensive research programme on Vierendeel joints in hollow structural sections (HSS). A total of 29 specimens comprised of five distinct connection types were tested and their strength and stiffness properties were recorded.As most of the joints tested behaved in a semi-rigid manner, a stiffness method for analysing Vierendeel trusses comprised of such joints is presented. Design curves for prediction of joint strength are proposed and design examples of Vierendeel trusses under panel point loading are analysed.Two joint types are recommended. These are the haunch type of connection and the chord flange stiffener, both of which have adequate strength and stiffness characteristics.
Ultimate strength in diagonal splitting of reinforced concrete thin wall panels
Authors: Zielinski Z. A. , Abdulezer Alfred
Published: January 2010

Research carried out on reinforced concrete beams and especially on deep beams show that inclined cracking due to shear does not terminate the work capacity of a beam if a sufficient amount of the main tensile reinforcement is being well anchored beyond the support even if there is not much web reinforcement. Beams, even with inclined cracks, may be able to withstand further loading until they reach the diagonal splitting strength limit due to what often has been called arch behaviour.The authors have now attempted, on the basis of their own recent and previous research work, to present a simple formula which allows the estimation of the necessary web reinforcement and strength after diagonal splitting has occurred. The amount of web reinforcement required for the above ultimate condition is, in most cases, less than that required according to the traditional shear theory and present requirements for deep beams, as specified in ACI-318-71, Section 11.9. There are also cases where more web reinforcement is required than specified by present ACI practice; these are listed in conclusions. This would imply that there is a necessity for some revision of ACI-318-71, in order to eliminate any possible cases of dangerous under-reinforcement of deep beams in the vicinity of supports.
Commentary on the design of glass (draft for public comment)
Authors: Hu F
Published: January 2010

The following draft Commentary on the Design of Glass has been prepared under the auspices of the Associate Committee on the National Building Code and is now available for public comment from the Secretary of the Associate Committee.The draft Commentary is being published in Can. J. Civ. Eng. as a means of advising those interested engineers who might not normally be made aware of its existence through the medium of NBC/NFC News.The purpose of the Commentary is to make available to the designer detailed information to assist in the interpretation of Code requirements for the design of glass. Although there will be general requirements for glass design included in the 1977 NBC it was not possible to complete public review of the proposed Commentary in time for it to be published in the 1977 Code series. Instead it is intended that the Commentary be issued in the 1979 edition of Supplement No. 4, "Commentaries on Part 4 of the National Building Code".Readers are encouraged to submit comments on the Commentary and these should be sent directly to the Secretary of the Associate Committee. All comments received will be reviewed by the Standing Committee on Structural Design who are responsible to the Associate Committee for Part 4 Design of the NBC and Supplement No. 4.
Réactivités aux alcalis du grès de Potsdam dans les bétons
Authors: Berard J. , Lapierre N.
Published: January 2010

Numerous old concrete structures showing signs of disintegration are found in the Beauharnois–Valleyfield area located to the southwest of Montreal.After a short examination of some of the structures, evidences of alkali–silica reactivity appear to be related to sandstone aggregates belonging to the Potsdam group. This rock type, although common in the state of New York and in the provinces of Quebec and Ontario, is only very rarely used as an aggregate owing to its hardness and abrasion. Nevertheless, when available from important excavation sites it has sometimes been used as an aggregate with ordinary alkali-rich cements.The products of the chemical reactions between the siliceous aggregates and the cement were studied with a polarizing microscope, a scanning electron microscope, an electron microprobe, and a thermobalance and differential thermoanalyser.During these studies superposed layers of silica gel of variable composition were found and secondary minerals were also identified. The Na/K ratio was found to increase in the more recent layers of silica gel suggesting that sodium could have been added within the structures as winter de-icing salts.The hypothesis is put forward that even if a low alkali cement is used with this Potsdam sandstone, alkali–silica reactivity could still occur in the presence of alkalies from external sources.
Analysis of wood diaphragms and trusses. Part I: Diaphragms
Authors: Foschi Ricardo O.
Published: January 2010

An analysis for wood diaphragms is presented taking into account the deformation of the connections. The load–deformation characteristics for the connectors are assumed to be nonlinear. A numerical example is presented and comparisons are made with experimental results on a 20-ft by 60-ft (6-m by 18-m) plywood and decking roof diaphragm. The agreement between the test results and the predictions of the analysis is shown to be good.
Bayesian model discrimination for BOD analyses
Authors: Constable Thomas W. , McBean Edward A.
Published: January 2010

The Hsiang–Reilly method, a discrete Bayesian model discrimination technique, is used to select the best model of several alternative models to describe data relating observed BOD exertion as a function of time. Use of this approach avoids the need for linearization of equations and results in distributed probability estimates of the parameter magnitudes rather than simply point estimates. A case study application to the raw influent and primary effluent of the Waterloo Pollution Control Plant is included. The results indicate that although a three-parameter model often gives a better fit to observed BOD data than the two-parameter first-order model, differences between the BOD-progression curves for the models are often so small as to be insignificant. In view of these small differences, and considering that none of the proposed models could adequately describe observed deviations from the exponential BOD curves, the use of the first-order equation to describe BOD-progression relationships for the Waterloo Pollution Control Plant appears to be justified.
Structural analysis using a basic frontal method
Authors: Harman D. J.
Published: January 2010

The organization and bookkeeping routine are described for a basic frontal program which is suitable for frame analysis of large structures using a minimum of computer core capacity and auxiliary storage. This displacement method analysis automatically partitions the stiffness matrix of an idealized structure in a manner similar to substructuring. Space frame, plane frame, grid and truss members can be mixed in one input and the program automatically will take advantage of these modelling assumptions. Joint numbering has no effect on efficiency. However, for an efficient solution, a physical sequence of the members in the structure must be used as the sequence for presenting the idealized members to the solution routine; therefore, the solution can be visualized to progress as a ‘wavefront’ moving through the structure. The analyses of three structures are outlined and the time required for each part of their solution is listed; a maximum of 15% of the solution time was used for frontal bookkeeping. The penalty for using a frontal method rather than a band matrix algorithm is small, if any, because for many problems, the frontal bookkeeping time can be offset by a reduction in the time required for solving the equations.
Damping of floor vibrations by constrained viscoelastic layers
Authors: Farah A. , Ibrahim I. M. , Green R.
Published: January 2010

Formulations are presented for enhancing the serviceability of one-way floor systems subjected to dynamic loading through the use of constrained viscoelastic layers. The constrained layers are combined with the floors and the resulting systems are analyzed as sandwich structures using a double Fourier series approach. Results indicate that the damping of the resulting sandwich beams is governed by factors related to the elastic and geometric properties of the constrained layer and the constraining system (i.e. cover plates and beams) and the loss modulus of the viscoelastic material, and is highly influenced by the location of the viscoelastic layer in the sandwich beams. Optimum designs of the sandwich beams are obtained using the box algorithm optimization technique.
The fracture of wood in tension parallel to the grain
Authors: Mindess Sidney
Published: January 2010

The fracture of commercial Hem-Fir boards in the LR and LT modes was studied, using both saturated and air-dry specimens. Notched samples were tested in flexure (third-point loading). It was found that the concepts of linear elastic fracture mechanics could be applied, even when the crack extension was in a direction perpendicular to the initial notch. However, the physical interpretation of the apparent fracture toughness, [Formula: see text], remains unclear. It was also found that the apparent flexural stsrength increased as the size of the uncracked ligament decreased. Finally, the results indicated that both the nominal flexural strength and the fracture toughness were greater for the saturated specimens, probably due to an increase in viscoelastic behaviour at high moisture contents.
Probabilistic analysis of ice – offshore structure interaction using enveloping step function power spectral densities
Authors: Sundararajan C. , Reddy D. V.
Published: January 2010

A probabilistic analysis is presented for the response of offshore structures subjected to random forces due to ice floe movement. Analysis based on the averaged power spectral density of the ice force fluctuations is shown to result in unreliable designs in certain cases, owing to sensitivity to even small errors in the calculated natural frequencies of the structure. To overcome this drawback, an ‘enveloping, step function power spectral density’ is proposed. A single-degree-of-freedom system and a three-dimensional offshore tower are solved as examples.
Parameter estimation for the first-order BOD equation using nonlinear techniques
Authors: Constable Thomas W. , McBean Edward A.
Published: January 2010

Two nonlinear parameter estimation techniques are used to obtain expected values, variances, and covariance estimates for L and k in the first-order BOD equation. The techniques are compared with a number of other BOD parameter estimation methods with respect to both estimated values of L and k and necessary assumptions about the measurement error structure of BOD analyses. The techniques that historically have been used to estimate the parameters in the first-order BOD equation are shown to often give erroneous answers because of their use of an incorrect error structure.A case study application of the methodology to the raw influent and primary effluent of the Waterloo Pollution Control Plant is included.
Commentary on Section 4 Sawn lumber of CSA 086-1976 Code for the engineering design of wood
Authors: Wilson Carl R.
Published: January 2010

This commentary provides background to the requirements found in Section 4 Sawn lumber of CSA Standard 086-1976 Code for the engineering design of wood.
A transportation planning model for detailed traffic analyses
Authors: Fisk C.
Published: January 2010

This paper contains a brief outline of a transportation planning model developed for the purpose of providing detailed analyses of commuter traffic. It sets out to model the movement of automobile, transit and pedestrian traffic taking into account the interaction between and within each of the traffic components. The model is most appropriately applied to areas of high traffic activity, such as the central business district of a metropolitan area or arterial streets of a region-wide network during peak demand.
Preliminary design of the activated sludge system — standard codes versus kinetic model equations
Authors: Hart Frederick L.
Published: January 2010

This paper discusses the origin and concepts of kinetic model equations and standard specifications used to size a biological treatment system (size of aeration tank and aeration requirements). They are shown to yield very similar calculations for a domestic type of waste water, but may yield much different values if the waste water behaves differently than domestic waste. The kinetic model approach, therefore, should be considered more flexible and superior in its ability to yield appropriate design values.
Suppression de la couverture de glace par un rejet thermique
Authors: Robillard Luc
Published: January 2010

The thermal discharges from various sources that occur during winter may prevent ice formation at the free surface. In order to predict the extent of the free surface without ice, numerical models of thermal discharges should take into account: (1) the particular heat transfer at the free surface that occurs during winter time and (2) the nonlinear relationship between density and temperature for water near 0 °C. This article indicates a method of modifying existing models and presents some results obtained from a modified buoyant surface jet model.
A method for calculation of the maximum permissible thermal shock to avoid cracking in the construction of the CN Tower
Authors: Ghosh Ram S. , Bickley John A.
Published: January 2010

The CN Tower is the tallest free-standing structure in the world. The later part of the slip-forming operation of the superstructure was carried out during the coldest period of the Canadian winter. Protection had to be designed therefore to overcome several problems. From the results it is concluded that graduated protection offered reliable and economic means of crack prevention and strength development throughout the winter slip-forming operation.
Marsh Lake Dam
Authors: Thompson W. J. , Engweiler J. A. , Gilbert-Green J. A. , Gordon J. L. , Shery R.
Published: January 2010

The paper describes the design and construction of a steel cantilever dam on the Yukon River, approximately 24 km upstream of Whitehorse. The dam can retain 2.4 m of water to store a volume of 1.02 × 109 m3 for use at the Whitehorse Hydroelectric Power Plant. Although the dam is small by today's standards, its design and construction posed several interesting problems, which were overcome by an innovative structure that was built on a pervious foundation, without the benefit of cofferdams, without diversion and with little obstruction to the flow of the river.The design concept has not previously been used in Canada and utilizes a combination arrangement of H-section piles, interconnected with Z-sheet pile sections to form a continuous steel wall. Alternate H-piles extend above this wall to provide openings for vertical lift gates and to support a prefabricated steel deck. The pile driving equipment worked from this deck when driving subsequent piles. Prefabricated gate guides were positioned between the extended H-piles and held in place with tremie concrete.The dam was constructed in approximately half the time and at about half the cost that would have been required for a conventional concrete structure.
Live load field test on the Muskwa River Bridge
Authors: Cheung M. S. , Chan M. Y. T.
Published: January 2010

The performance of a steel–concrete composite box-girder bridge is examined through a series of live load field measurements. This paper describes the measurement program and the results obtained, as well as comparisons wherever possible between the observed values and those obtained from beam theory calculations and bridge code equations. It was found that the measured strains were generally much lower than the design values and that for bridges with asymmetrical cross sections, a beam theory calculation using bridge code live load distribution formulas can lead to nonconservative results.
Calcium chloride in concrete — applications and ambiguities
Authors: Ramachandran V. S.
Published: January 2010

Many aspects of the action of calcium chloride in concrete are ambiguous, controversial, or incompletely understood. Examples include: (a) the restrictive definition of calcium chloride as an accelerator; (b) the lack of clarity in prescribing the dosage for practical applications; (c) the classification of calcium chloride as an antifreezing agent; (d) the misconception regarding corrosion of reinforcement in the presence of CaCl2; (e) the divergence of opinion on the mechanism of action; and (f) incomplete understanding of the changes in the intrinsic properties of cement containing calcium chloride. This paper attempts to deal with these aspects citing typical examples.
Numerical simulation of air bubbler systems
Authors: Ashton George D.
Published: January 2010

The use of air bubbler systems to suppress ice formation is a technique that has been applied in a variety of situations with varying degrees of success. In 1974, two-dimensional line source bubbler systems were analyzed by G. D. Ashton in an effort to make available a tool that may be used in the design of a bubbler installation. That analysis was a steady-state evaluation of the melting rate of an ice cover above a bubbler system predicted on the basis of the input variables (depth, air discharge rate, water temperature). In actual operation, however, a bubbler 'sees' changing conditions such as diurnal and longer-term weather conditions, varying water temperatures and depletion of the available thermal reserve.The simulation presented herein uses the steady-state analysis developed earlier by Ashton and steps it in time with each new condition determined from the results of the previous time step. In this sense the analysis herein may be considered quasi-steady.Results of the simulation are presented for an example case for a winter in Superior, Wisconsin, and illustrate the variation in width of open water area with changing weather conditions with good comparison to field observations.
A screening model for heated discharge siting investigations
Authors: Hoglund Glen M. , McBean Edward A.
Published: January 2010

The natural heat dissipating abilities of Canadian water resources are examined in order to determine their variability both spatially and temporally. The cooling performance is expressed in terms of the surface heat exchange coefficient K and the equilibrium temperature E. The computational procedure, reflecting some adjustments to recognize Canadian conditions, is shown to satisfactorily reproduce water temperatures in two Canadian lakes of moderate size.Examination of data from 115 stations across Canada reveals that three regions are particularly suited to heat dissipation, namely southern Saskatchewan, southern Ontario, and parts of the Maritimes. Considerable variability is apparent in both K and E, both within a year and from year to year.Several examples are used to demonstrate how the information compiled in this paper can be used during the preliminary screening stage of power plant siting investigations.
L'érosion des rives dans le Saint-Laurent
Authors: Ouellet Yvon , Baird William
Published: January 2010

The processes contributing to the erosion of river banks are usually complex, and their interdependence makes it practically impossible to quantify the contribution of any one phenomenon to the total amount of erosion. Such is the case if one is concerned both with wave action during the ice free season and with ice action in winter.With respect to the erosion of the banks of the St. Lawrence River between Quebec and Montreal, it seems however, that the phenomena of primary importance are those resulting from the action of waves. The formation of ice, on the contrary, tends to protect the shores from winter's rigorous climatic conditions.Where the river is relatively wide, most erosion of the banks is produced by natural phenomena resulting from wind generated waves. Above Quebec, however, where the river is narrower, waves generated by the passage of ships may cause considerable damage to the shoreline. In order to establish the relative contribution of different phenomena to the erosion of the shore, it may be useful to compare the importance of this pounding by ship generated waves, which has an artificial character, with that of the erosion produced by natural phenomena. An evaluation of the relative erosive potential of these processes was made possible by measurements of waves taken at Lanoraie, Champlain, and Saint-François de l'Ile d'Orléans.
Stability of flexible conduits embedded in soil
Authors: Abdel-Sayed George
Published: January 2010

After final installation, underground flexible conduits are subjected mainly to ring compression. Therefore, it is important to check the stability of the conduit walls, which may govern the load carrying capacity of such composite soil–steel structures.The approaches developed by different investigators to deal with the problem of buckling are discussed and examined critically in the paper. This leads to the recommendation of the following formula for calculating the elastic buckling stress fb:[Formula: see text]in which E = modulus of elasticity of the conduit material; R = radius of the conduit; r = radius of gyration of the conduit walls; ψ = reduction factor for buckling stress of conduits under shallow cover h, where[Formula: see text]and[Formula: see text]in which E′ = modulus of soil reaction; I = moment of inertia per unit length of cross section of conduit wall; B = 1.22 for the sides and bottom in which the conduit walls displace towards the soil and B = 1.22[1 + 2(EI/E′R3)1/4] for the upper portion of the conduit wall where the radial displacements are towards the inside of the conduit.Inelastic buckling is considered to start when fb = half the yield stress fy. A parabolic equation is assumed for the transition zone between full yielding (kR/r = 0) and the elastic zone at fy/2:[Formula: see text]
Recent developments in regional transit for Greater Vancouver
Authors: Sullivan Brian E.
Published: January 2010

The transit system serving Greater Vancouver has high ridership and a high rate of growth. Using as a base the well-designed, well-patronized trolleybus grid in the City of Vancouver, an inter-connected suburban bus network has been created, with radial, cross-radial, and local routes meeting on a timed connection basis at suburban shopping centres and other foci. Planners' thoughts for the future include greater emphasis on the micro and macro aspects of land use and relations to transit; the use of capital intensive modes for heavy trunk routes; and the use of various forms of para-transit for low-density and certain feeder applications.
Design criteria for exposed hydro penstocks
Authors: Gordon J. L.
Published: January 2010

At present there are no national codes for the design of exposed hydro-electric penstocks. Thus an engineer must either make reference to other national codes for similar work, such as the American Society of Mechanical Engineers boiler and pressure vessel code or the American Water Works Association Standard for steel water piping, or he must write his own code and is then faced with the decision of having to select design criteria that must cover a wide range of steels; different operating and waterhammer conditions; a wide range of quality control procedures used in manufacture and erection of the penstock; and different types of penstocks, isostatic where the stresses can be calculated with precision, and hyperstatic where the stress calculation is more imprecise. This paper discusses design criteria, factors of safety, and corresponding quality control procedures that can be used for either isostatic or hyperstatic penstocks using mild, intermediate, or high strength steel for penstocks supplying reaction of impulse turbines.
A strain energy criterion for failure of floating ice sheets
Authors: Beltaos S.
Published: January 2010

A failure criterion for floating ice sheets under stationary loads is presented, based on the concept of strain energy per unit volume and the results of some 40 prototype loading tests. The practical requirement for a time-independent failure criterion for ice, which is a viscoelastic material and thus subject to creep, is noted. Existing failure criteria are reviewed and shown to be unable to handle many practical situations. Subsequently, the concept of strain energy per unit volume is formulated and shown to provide a satisfactory failure criterion under varied loading histories. Analysis of the test results indicated the existence of a distinct instant marking the onset of failure of a loaded ice sheet. Because the behaviour of a loaded ice sheet between this instant and the final breakthrough of the load is partially random, it is suggested that the former be used as the practical limit of safety.
Behaviour of coupled non-linear shear walls
Authors: Pekau O. A. , Gocevski Vladimir
Published: January 2010

This paper describes an investigation of coupled non-linear shear walls subjected to lateral load increasing monotonically up to overall collapse. Overall collapse includes base hinges in walls as well as yielding of connecting elements over either all or some portion of the total height. Curves useful for preliminary assessment of potential seismic performance of a structural system are generated following a parametric scheme. Particular attention is focused on connecting beam as well as system ductility capacities required to achieve overall collapse.
Ice management of Lac St. Pierre, Quebec
Authors: Danys J. V.
Published: January 2010

This shallow lake with a narrow outlet is a barrier to the free movement of ice downstream from Montreal. It has caused ice jams and flooding in many areas between Lac St. Pierre and Montreal, including its own low areas. In 1866, 50 people lost their lives during the spring flood. An ice cover forms quickly over the lake so that navigation to and from Montreal has been closed sometimes for 5 months. In 1928 the icebreakers of the Ministry of Transport started to open a channel during the winter to facilitate ice movement. In the 1960’s, other control measures such as ice booms, artificial islands, and lightpiers were introduced. Continuous observation and recording of ice movement and the collection of the data required to estimate ice forces on structures, such as ice thicknesses, the properties of ice, and actual field measurements of ice forces have been carried out. Today, ice management of Lac St. Pierre and the St. Lawrence River ensures that Montreal is free of flooding and that navigation to this city is possible virtually all year round.
Special considerations in design of an asymmetrical shear wall building
Authors: Tso W. K. , Ast P. F.
Published: January 2010

Two special considerations in the design of the Harbour Square Apartment Complex in Toronto are presented. Firstly, due to the irregular shape and overall size of the building, volumetric change of the floor slab can become a potential problem. Actual shrinkage tests were carried out on the materials used to estimate the ultimate shrinkage strain. A scheme of permanent and temporary construction joints was designed to solve the floor slab's shrinkage problem.Secondly, due to the asymmetrical nature of the floor plan, the distribution of wind loads on different shear walls was calculated based on a special three-dimensional computer program, taking torsion of the building into account. This program treats the shear walls as thin-walled beams coupled by the diaphragm action of the floors. The program is efficient both in terms of input data and CPU time and is believed to be a viable design tool for highrise shear wall buildings.