bluuebunny/crossref_metadata_2025 huggingface dataset:
Winter concreting in Canada
Authors: Ghosh R. S. , Mustard J. N.
Published: January 2010

This paper deals with the pros and cons of concreting in sub-zero weather and the practice and theory behind the requirements of the Canadian standards for cold weather concreting. It gives the minimum protection period for initial curing to prevent frost damage and the amount of insulation required to meet the standards for various weather conditions. The problem of the thermal stress produced as the concrete cools under various degrees of restraint is dealt with in detail, and the cooling period required to avoid thermal stress cracks for various thicknesses of structures and weather conditions is given in graphical form. Examples of the use of insulation in slip forming and problems encountered in varying weather conditions are also included. Keywords: winter construction, concrete, insulation, curing, form work (construction), form removal, temperature, thermal shock, water–cement ratio.
Initiation of motion conditions for shale sediments
Authors: Magalhaes L. , Chau T. S.
Published: January 2010

Critical shear stresses for erosion of alluvial shale particles were investigated in a laboratory flume. Tests in the incipient motion conditions of individual particles showed that entrainment of shale bed particles takes place at mean shear stress values 40–50% smaller than other types of non-cohesive and coarse granular material. The low density and platy shape of the shale particles may induce high lift forces, which would account for a decrease in the resistance to erosion of shale channels and greater rates of bed-load transport. Keywords: channel stability, critical shear stress, flume tests, initiation of motion, shale gravels, single particles, weak bed material movement.
Minimum cost design of sulphur concrete pavements
Authors: Loov R. E. , Gillott J. E. , Jordaan I. J. , Shrive N. G.
Published: January 2010

Two types of paving materials have traditionally been used for surfaces that must be better than can be provided by materials such as gravel or soil-cement. Portland-cement concrete has been designed based on procedures that recognize the rigid nature of this material. Asphaltic concrete has, on the other hand, been designed based on a recognition of the flexible nature of this material.We have found that, with minor differences in the amounts of suitable additives, sulphur concrete can be tailored to have different stiffness characteristics ranging between asphaltic concrete and Portland-cement concrete. With this material we have an opportunity therefore to choose the material stiffness that will result in the minimum pavement thickness for a given situation. The optimum material stiffness has been determined, based on different sub-base stiffnesses for standard wheel loads.The results of this investigation should be of interest to all engineers faced with the responsibility for designing pavements. Keywords: pavement, sulphur concrete, minimum cost design, highways.
Tests of composite beams with web holes
Authors: Redwood R. G. , Poumbouras G.
Published: January 2010

Tests of composite beams comprising a concrete slab supported on a steel deck and a steel wide-flange shape containing large web openings are described. Special attention is directed to the amount of shear connection between slab and steel section in the region of a web hole, and on the effect of construction loads acting on the steel section prior to composite action being effective.It is shown that limited shear connection at the hole will significantly affect the strength when loading produces a high shear-to-moment ratio, and a theory is presented which conservatively takes this into account. The effect of construction loads on unshored construction is shown to be small when these do not exceed 60% of the non-composite beam resistance at the hole.
Local buckling capacity of C-shaped cold-formed steel sections with punched webs
Authors: Loov Robert
Published: January 2010

Load tests were carried out on 36 stub column samples of cold-formed steel studs having 38.1 mm wide × 44.5 mm long holes punched through their webs, steel thicknesses of 1.21–2.01 mm, and overall section depths of 63–204 mm. Based on these tests a best-fit equation for the effective width of the unstiffened portion of the web beside the holes has been developed. Suggested design equations have been proposed. The test results support the present equation for the average yield stress [Formula: see text] in Canadian Standards Association Standard S136-1974 but the present code equations for unstiffened plates are unduly conservative when applied to the design of the web adjacent to openings of the size considered.
The structural design of Terminal 2 parking structure at Toronto (Malton) International Airport
Authors: Yan H. T.
Published: January 2010

This paper presents the salient features of the structural design of the Terminal 2 parking structure at Malton Airport. The structural problems encountered in the design of a large parking structure and the solutions adopted are discussed and evaluated. Particular attention is drawn to the problem of structural movements due to the effect of volume changes in the concrete from temperature, drying shrinkage, and stress-creep which can lead to distressful cracking. A new formula is proposed for the spacing of expansion joints, which is dependent on the ground storey column segment. The effects of foundation restraint to the structural movements caused by volume change for different types of foundations (e.g. caisson piles, spread footings) are evaluated. The criteria for the selection of expansion joint hardware, topping concrete mix, and deck-sealing systems, with the aim of enhancing the durability of the structure, are postulated.
Beam-and-slab bridges with small skew
Authors: Surana C. S. , Humar J. L.
Published: January 2010

In the design of beam-and-slab skew bridges, it is common practice to treat a bridge with skew angle up to about 20° as a right bridge having a span equal to the skew span of the bridge being designed. The validity of this assumption is examined by analysing several bridges with skew angles varying from 0 to 30°. It is concluded that the right bridge analysis gives a good estimate of the design moments, flexural shears, and deformations in the longitudinal girders but cannot provide reasonable predictions for the values of torsional shears and rotations.
Beach fecal coliforms
Authors: Palmer Merv D. , Dewey Raymond J.
Published: January 2010

A combination of the STORM runoff model and a two-dimensional dynamic lake type model successfully reproduced the fecal coliform levels of an urban beach on a lake in the Ottawa River. The elevated fecal coliform levels were associated with rainfall events and runoff from two large catchments upstream of the beach. Due to prevailing conditions in the lake the second largest summer storm did not produce elevated fecal coliform levels while the third and fourth largest storms did. The models predicted these events.The STORM model was calibrated on a subcatehment and supplied the runoff flow volumes and pollution levels to the dynamic lake model. The other input data for the lake model were supplied by field measurements.The models were used to assess the effectiveness of management options to improve the water quality on the beach. The most cost-effective option was identified by the model predictions. Key words: beach fecal coliform predictions, stormwater beach fecal coliforms, storm, runoff, modelling.
Ultimate strength of eccentrically loaded cold-formed angles
Authors: Madugula Murty K. S. , Ray Sujit K.
Published: January 2010

Results of the tests carried out on fifteen 65 × 50 × 4 mm (nine specimens with long leg connected and six with long leg out) and nine 55 × 55 × 4 mm eccentrically loaded cold-formed single angles are presented. The test specimens were connected at the ends to the test frame by bolts on one leg and were subjected to eccentric thrust (eccentricity about both principal axes). Three different slenderness ratios (80, 120, and 170) and three different end connections (one-, two-, and three-bolt) were used in the test program. Experimental failure loads are compared with the loads computed according to the general theory of torsional–flexural buckling, ASCE Manual No. 52, and the ECCS recommendations. The effect of the location of shear centre and the magnitude of warping constant on the ultimate strength of cold-formed single angles is discussed.
Ice cover melting in a shallow river
Authors: Calkins Darryl J.
Published: January 2010

The heat transfer coefficients computed from field data on both ice cover melting and water temperature attenuation are higher than the values one would compute based on extrapolation of previous laboratory flume data. The computed heat transfer coefficients were relatively consistent when calculated from the water temperature decay data. Consistent results were also obtained with one set of very detailed ice cover melting data.The diurnal fluctuation in water temperature from the freezing point to values of 0.4–0.6 °C was associated with the incoming solar radiation and the open water surface area. The measured water temperature distribution beneath the ice cover at a particular cross section varied from 0.2 to 0.6 °C due to the influence of frazil ice and flow distribution. In the open water reaches the water temperature was essentially fully mixed vertically but lateral variation across the river ranged from 0.1 to 0.3 °C.The average daily melting of the ice cover often exceeded 5.0 cm and at some locations the rate was as high as 8 cm/d. The melt was not uniform across the section but was highly dependent upon the flow conditions, velocity, and depth. The ice cover melting for this year only occurred during the daylight hours as the air temperatures dropped below 0 °C at night and the water temperature likewise decayed to its freezing point.
Construction du barrage OA-11 sur la rivière Eastmain
Authors: Massiéra Michel , Pelchat Claude
Published: January 2010

The OA-11 dam is the most important earth structure of the Eastmain – Opinaca – La Grande (EOL) project within the "La Grande" hydroelectric complex at James Bay, Quebec. Three rivers were diverted to the La Grande River to increase the hydroelectrical potential of LG-2 power plant. Dam OA-11, 33.2 m high, has a zoned section with an impervious central core. The soil conditions of the existing overburden along the 3214 m dam axis were very variable.The presence of pervious overburden at considerable depth along the dam axis makes it necessary to use an impervious cutoff under most of the length of the dam. On the right shore, a slurry trench was therefore built. It is 1.5 m wide, 2180 m long, and varying in depth from 3 to 22.7 m. In the river bed, the dam was built on an embankment pad of granular material pushed into the water and compacted by vibroflotation. A cast-in-place concrete wall was constructed to insure a cutoff through the pervious soils of the pad and foundation. This diaphragm wall is 595 m long, 0.6 m thick, and varying in depth from 2.6 to 35.7 m.This paper describes the different phases in dam construction with emphasis on techniques used for river closure. Key words: dam, compaction, construction, diversion, closure, cast-in-place concrete wall, river, slurry trench, vibroflotation.
Une génération interactive des données pour appliquer la méthode des éléments finis
Authors: Charron M. Sylvain , Marche M. Claude
Published: January 2010

The advent of new and powerful computers, during the last few years, has resulted in a widespread application of numerical models to solve engineering problems. At the present time, one of the popular numerical techniques utilised by engineers is the finite element method.In order to generate and organize in an efficient manner the complex data structure resulting from its application a new modular approach has been developed. This approach is particularly suited to the treatment of heterogeneous domains often encountered in engineering practice.A modified version of the "Multigrid" technique is used to solve the Thompson elliptic equations in order to generate a 2-D finite element grid. A graphical interactive computation system is used and we can consider implementing the programs in a micro- or mini-computer. Key words: computer-aided design, finite element grid generator.
Surface streaking and fecal coliform levels
Authors: Palmer Merv D.
Published: January 2010

The measurement of the dilution and die-off of fecal coliforms in high velocity, wind-generated surface currents is discussed. The dispersion in the streaks is similar to that found in oil slicks. It was found that the high velocities and slower growth rate of the dispersion in the streaks resulted in fecal coliform levels about four times higher than those found in water areas not affected by the streaking. Key words: surface streaks, fecal coliforms—dilution, bacterial levels.
Comparative studies of medium-span box girder bridges with other precast systems'
Authors: Kulka Felix , Lin T. Y.
Published: January 2010

Recognizing the large market for medium-span bridges, the building industry has focused its attention on the economical construction of these structures. Mechanized construction and the use of standardized members have become important aspects for this type of structure, owing to the numbers to be constructed in the near future and the large size of some of these projects. This paper deals with a comparison of four structural prestressed concrete systems applicable to medium spans: box sections, I-girders, T-girders, and wing sections. Cost comparisons are presented, and conclusions as to the choice of structural sections for optimum medium-span construction are included. The material is derived from a study the authors' company prepared for the United States Federal Highway Authority on the feasibility of standardization of segmental box girder bridges. Key words: bridges, box girders, precast concrete, prestressed concrete.
Analysis of winter heat flow in an ice-covered Arctic stream
Authors: Wankiewicz A.
Published: January 2010

The growth of river ice during the winter of 1977–1978 is modelled for Caribou Creek, an Arctic stream near Inuvik, Northwest Territories. In midwinter, a period of extensive river icing activity, the stream flows over shallow sections of channel via narrow conduits beneath the ice cover. These relatively high-velocity sections are shown to be concentrations of locally generated friction and convected streambed heat. A nonuniform flow model is used to represent friction generation and heat transfer to ice in both shallow and deep sections of the channel. Bed heat flux is simulated from thermal measurements in the unfrozen ground beneath the channel. A relationship between flow width at shallow sections and recorded air temperature, inferred from streambed temperature recordings, is reproduced by simulating the effect of warm and cold spells on flow conduit dimensions. The low air-temperature threshold for increase in conduit cross section, −20 °C, is shown to result from heat transfer rates which offset the reduced heat loss from an insulating snow cover. Key words: ice formation, streamflow, Arctic regions, thermal analysis.
Scour control at Outlook Bridge—A case study
Authors: Smith C. D.
Published: January 2010

This paper covers the chronology of events at the east abutment of Outlook Bridge on the South Saskatchewan River from 1936 to 1981. It traces the early discovery of deep scour, a failed attempt at remedial action, a model test, a successful solution with riprap, and later, the addition of a guide bank.Abutment scour on the prototype under flood conditions was observed to extend about 5 m below the footing, endangering the stability of the structure. Attempted remedial measures using bags filled with sand–cement were unsuccessful. An analysis of the river regime was undertaken and a 1:100 scale hydraulic model was constructed and tested. The model indicated that either a guide wall or riprap apron would give the required protection. Riprap was selected on the basis of least cost, but a guide bank was added at a later date to further improve conditions. Key words: bridge, scour, hydraulic model, riprap, guide wall, guide bank.
Biaxial bending of cold-formed angle members
Authors: Madugula Murty K. S. , Ray Sujit K.
Published: January 2010

Theoretical load–deflection relationships for cold-formed angles under biaxial bending using the Galerkin method are presented. The computational difficulties encountered in the exact solution of differential equations of equilibrium involving 12 unknown constants in 12 simultaneous equations are pointed out. A computer program for pinned-end boundary conditions was developed to estimate the deflection components of the shear centre, to calculate the total stress at various points in the cross section, and to predict the ultimate strength of the cold-formed angle sections connected by one leg. Failure is assumed to have occurred when the total stress at any point on the cross section reaches the value of yield stress, compressive or tensile, or when there is a change of sign for at least one of the deflection components. A table giving the ultimate compressive strength of two commonly used cold-formed angles for various gauge distances is included. The theoretical load–deflection curves are compared with experimental results and typical curves for three test specimens are also presented.
Forces at flange–web connections in T-beams
Authors: Razaqpur Abdul Ghani , Ghali Amin
Published: January 2010

The flanges of T- and I-beams are subjected, near their junctions with the web, to three in-plane forces: Nx, Ny, and Nxy, where x and y are horizontal axes parallel and normal to the beam axis. The finite element method is used to study the variation of these forces in T-beams under point or line load. It is concluded that forces Nx and Nxy can be determined for design purposes using conventional engineering beam theory. Force Ny, on the other hand, cannot be determined by available closed-form solutions. Based on a detailed parametric study, a simplified procedure is proposed for determining Ny. Key words: beams (supports), connections, finite element, flanges, loads (forces), T-beams, webs (supports).
Improvements in calibration and understanding of the competing opportunities model of trip distribution
Authors: Sharma Satish C. , Soliman Afifi H.
Published: January 2010

This note suggests a method for improved calibration of the competing opportunities model of trip distribution. The method, called COMNEST, includes three steps: (1) selection of a suitable uniform width of time bands for the study area; (2) determination of the width of the first time band to achieve best-possible results; and (3) improvement in the accuracy of prediction of the dependent variable for the zones within the first time band. The third step involves a redistribution of the total number of trips predicted for the first time band among the traffic zones within the first time band by reapplying the competing opportunities model concept. Using the examples of trip distribution for Edmonton, Winnipeg, and Washington, DC, it is clearly shown in this note that the application of the suggested method can considerably increase the accuracy of the competing opportunities model. Key words: trip distribution, competing opportunities model, urban transportation planning, traffic forecasting, urban planning.
Development, availability, and use of engineering computer programs
Authors: MuftiSau Aftab A.
Published: January 2010

In the last decade, software engineering has emerged as a discipline very useful for computer application programmers in various engineering fields. In this paper the author considers the programming and management techniques for developing useful and commercially viable engineering software that may be used in the analysis and design of civil engineering projects. The issue of utilizing existing software effectively and efficiently is also discussed. At the conclusion of the presentation, several recommendations are made to encourage engineering software development in Canada. Key words: engineering, software engineering, software, computers, computer service bureaus, software directories.
Charts for water hammer in high head pump discharge lines resulting from pump failure and check valve closure
Authors: Ruus Eugen , Karney Bryan
Published: January 2010

Maximum pressure head drops and rises resulting from pump failure and subsequent check valve closure are calculated and plotted for a simple pump discharge line at pump end, midpoint, and three-quarter point. Basic parameters such as pipeline constant, pipe wall friction, complete pump characteristics, and pump inertia constant are accounted for in the analyses. Computer studies indicate that pipe friction, pipeline constant, and pump inertia have a major effect on pressure head drops and rises.Studies indicate further that whereas for large pump inertia the pressure head rise or drop at the midpoint is only moderately larger than one-half of the rise or drop at pump end, for small pump inertia this difference is much greater. For very small pump inertia, the pressure head drop or rise at midpoint approaches the values at pump end. This increase in pressure head drop and rise for very small pump inertia is even more pronounced at the three-quarter point.
The effect of clustering of flood peaks on a flood risk analysis for the Red River
Authors: Booy C. , Morgan D. R.
Published: January 2010

The nearly 100 year record of spring flood peaks on the Red River at Winnipeg, Manitoba, shows a clustering of high annual peak flows that is possibly, but not likely, due to chance. A similar degree of clustering has been observed in other long-term geophysical records. It can be measured by means of the Hurst statistic. Clustering increases the uncertainty in the parameters of the probability distribution of peak flows estimated from the record. As such it profoundly affects the weight that must be given to the unusually high historical floods that preceded the period of record, in particular the 1826 and the 1852 floods. Incorporating this historical information in the probability analysis requires a time series model that tends to produce the appropriate degree of clustering. A fractional noise model was adopted for this purpose. Bayes' theorem was then used to update the distribution parameters, obtained from the record, with the additional information about the historical floods. The result shows the flood risk to the City of Winnipeg and the Red River Valley to be substantially higher than was estimated by conventional methods that assume serial independence of the peak flows. Key words: Red River floods, flood risk, historical floods, Hurst phenomenon, fractional noise, Bayesian probability distribution, Bayesian updating, time series.
Analysis of interconnected shear walls using wide column analogy
Authors: Harman D. J. , Henderson P. W.
Published: January 2010

Wide column analogy is used to create a frame composed of line members to represent a building that is braced by shear walls; some members, or parts thereof, are rigid. For partially closed core walls that are torsionally loaded, A. Girgis and B. Stafford Smith found that wide column analogy using common line members gave inaccurate results. They and A. Abate developed frame modules for use in lieu of wide column analogy.Herein, by using a line member with a specified shear parameter, it is shown that wide column analogy gives very similar results to idealizations that use frame modules. Further, based on the analysis of idealized frames, it is recommended that the use of this wall idealization be restricted to closed core walls that are torsionally loaded or segments of long walls around geometrical irregularities.
Microcomputers, management, and high-rise construction: the next step
Authors: Russell Alan D.
Published: January 2010

The attributes required of an integrated management information system that advances the state-of-the-art and that is responsive to the needs of general contractor project management personnel for high-rise construction are presented. These needs are elaborated upon through the mechanism of a framework for conducting research on construction management information systems.Emphasis is placed on planning and scheduling for repetitive construction and subcontractor control. The description of a microcomputer-based prototype system called REPCON, which incorporates many of the attributes identified, is provided along with results from field tests of the system. Recommendations for future research are given. Key words: high-rise construction, management information system, planning and scheduling, subcontractor control, field tests.
Résultats d'essais sur des assemblages soudés excentriques en flexion
Authors: Beaulieu D. , Picard A.
Published: January 2010

The development, by Butler and Kulak, of equations for the calculation of fillet weld resistance with relation to the angle of load application has improved the understanding of the limit states behavior of welded connections. For the design of welded connections subjected to shear and moment, Dawe and Kulak developed a method of analysis based on the principle of instantaneous center of rotation, which accounts for the actual load–deformation characteristics of the weld. Due to its complexity, the method of Dawe and Kulak requires the use of a computer. In order to make the method more attractive to the designer, Neis suggested some simplifying assumptions and at the same time criticized the work done by Dawe and Kulak. In the discussions that followed the publication of his results, various researchers expressed diverging opinions on several matters related to the theories.Since the proposed methods were based on the results of only 8 laboratory tests done by Dawe and Kulak, we have carried out a series of 24 tests. The results of these tests were compared with the theoretical ultimate loads obtained from the methods of Dawe and Kulak and Neis, and demonstrate that the proposed methods are adequate as long as they are used within certain limits and respect certain conditions.
Effet des systèmes entremises—diaphragme sur la stabilité des poteaux
Authors: Massicotte B. , Beaulieu D. , Picard A.
Published: January 2010

In this paper, the authors deal with the stability of columns braced by girt–diaphragm systems used as cladding in low industrial buildings. The main characteristics of this system are presented and past research, conducted at Cornell University, is reviewed. A new approach based on the finite element method is presented, as well as a series of tests used to validate the proposed method. Key words: diaphragm, finite elements, girt, column, stability.
Caractérisation des eaux usées de débordements de réseau unitaire
Authors: Lessard Paul , Lavallée Pierre
Published: January 2010

In 1981, the City of Québec signed a protocol with the Québec Ministry of Environment permitting the study of the impact of combined sewer overflows (CSO) during rain periods on the St-Charles River. One of the main study objectives was to characterize CSO, both quantitatively and qualitatively. Five main drainage basins, representative of the study area, were selected and sampled during nine rain events. Certain appraisals were made to explain the importance of the water quality variations during rain events in combined sewers, dry weather period influence on runoff quality, and "first-flush" phenomenon. Two principal conclusions have been drawn from these data: (1) the major part of the pollutant load routed through a combined sewer network during a rain event is generated by surface runoff and dragging of sewage deposits and (2) the overall water quality of CSO doesn't seem to vary much from one basin to another, even if the percentages associated with different types of land use (residential, commercial, industrial, etc.) are different. Key words: urban runoff, combined sewer overflow, rainfall, quality, concentration, load.
Bridge analysis by the semicontinuum method
Authors: Jaeger Leslie G. , Bakht Baidar
Published: January 2010

Bridges are commonly idealized for live-load analysis either as grillages or as orthotropic plates. The former idealization is a discrete one in which the flexural and torsional rigidities in both the longitudinal and transverse directions are concentrated in discrete grillage beams. In the latter idealization, the various rigidities are uniformly distributed in the longitudinal and transverse directions. In a third type of idealization, a slab-on-girder bridge is represented by discrete longitudinal beams and a continuous transverse medium. This idealization has been used by A. W. Hendry and L. G. Jaeger to analyse bridges with negligible torsional stiffnesses. A generalized form of the Hendry and Jaeger method, which can now take account of finite longitudinal and transverse torsional rigidities, is presented in this paper. The results of the proposed method are found to be in excellent agreement with those from the well-tested grillage analogy method. It is demonstrated that the proposed method is rigorous, and is economical in computer storage and time. The method is ideally suited to the personal computer.
Analysis of the submerged radial hydraulic jump
Authors: Abdel-Gawad Sameh M. , McCorquodale John A.
Published: January 2010

Most of the research work on hydraulic jumps has dealt with their macroscopic behaviour. The important parameters in these studies were the sequent depth ratio and the jump length required for stilling basin design. Unfortunately, the internal flow in submerged radial hydraulic jumps has received very little attention. A complete mathematical model of the internal flow would permit the modeller to assess the possible scale effects in a physical model and to better estimate the cavitation potential.This study treats the internal flow characteristics of the submerged radial hydraulic jumps under different submergence and operating conditions. A numerical model based on the strip integral method is used to solve the governing momentum and continuity equations. The numerical technique uses velocity shape functions to permit the partial integration of the equations of motion. A Gaussian velocity distribution is used in the mixing zone and the power law is used in the inner layer. The model predicts the velocity distribution, water surface profile, decay of the maximum velocity, variation of the surface velocity, sequent depth ratio, jump length, and energy loss.A comprehensive experimental program was conducted in an expanding Plexiglas flume with a total angle of divergence of 13.5°. The results were used to calibrate and validate the model. The model predictions also compared well with the results of other studies.
Vibration criteria for assembly occupancies
Authors: Allen D. E. , Rainer J. H. , Pernica G.
Published: January 2010

A design procedure based on user acceptability of vibration is presented for floor structures that are subjected to rhythmic activities such as dancing and jumping exercises. The procedure is applied to different occupancies and floor constructions using available information on dynamic loading; the results are summarized as a table of minimum natural frequencies. The procedure is contained in the Supplement to the National Building Code of Canada 1985.
An international competition to predict the response of reinforced concrete panels
Authors: Collins M. P. , Vecchio F. J. , Mehlhorn G.
Published: January 2010

An international competition was organized to compare analytical methods for predicting the response of reinforced concrete elements subjected to general two-dimensional stress states. Four panels tested in a University of Toronto research program formed the subject of the competition. Entrants were asked to predict the panels' ultimate strength and load–deformation response, and to provide a brief description of the basis for their predictions.Twenty-seven entries from thirteen countries were received. Predictions of ultimate strength were generally higher than the experimental values, and were marked by coefficients of variation of up to 40%. Predicted strains were also much higher than observed, and had coefficients of variation of 50–100%. The analytical methods used varied from simple hand calculations to complex finite element procedures.This paper briefly reviews the physical properties, loading conditions, and observed response of the four test panels. Statistical details and general trends pertaining to the predictions received are discussed, and capsule summaries of the methods and assumptions used are presented.
A review of cracking of partially prestressed concrete members
Authors: Batchelor B. deV. , Shahawi M. El
Published: January 2010

A selective review of cracking of partially prestressed concrete members is presented. The main studies, together with the resulting methods for calculating maximum crack width, are critically examined. From an analysis of published test results it is shown that, in the light of the sparse data available, there is no point in using a complicated crack width formula for partially prestressed members. A simple expression for calculating crack width is proposed, which involves only the calculation of stress in the non-prestressed reinforcement. A strong case is made for further research in this area so that effects of the controlling parameters may be considered, where necessary. Key words: concrete (prestressed), cracking, crack width, partial prestressing.
The effect of a chloride-based accelerating admixture on the tensile strength of concrete
Authors: Makrides-Saravanos Elli , Rezansoff T.
Published: January 2010

Compression and tension tests were performed on specimens made from high-early-strength concrete, where the strength acceleration was achieved by using a chloride-based accelerating admixture. Comparison with specimens made from concrete without the admixture showed that the concrete with the admixture was significantly weaker in tension for equal compressive strength.Curing times ranged from 3 days to 3 or 4 months while compressive strengths ranged from 16 to 37 MPa depending on the batch and the age at testing. Three types of tension tests, the standard split cylinder test, the standard modulus of rupture test, and a pull-out test were used in the study.Current design equations that relate tensile strength of concrete to the measured compressive strength may overestimate the actual tensile strength of high-early-strength concrete where acceleration is achieved through the addition of an admixture. These equations are found in provisions for anchorage, development, and splicing of reinforcement, shear and torsion strength, and the prediction of service load deflections. Key words: concrete, accelerated strength, tensile strength, admixtures, curing, splitting tensile strength, modulus of rupture, strength correlations.
Outline of current analysis procedure for CANDU 600 MW reactor buildings
Authors: Mamet J. C. , Moselhi O.
Published: January 2010

Reactor buildings of 600 MW CANDU nuclear power plants consist of a prestressed concrete containment structure, cylindrical in shape with a double spherical dome, and of a reinforced concrete internal structure with heavy walls and slabs that support the nuclear reactor, the primary heat transport system, control and safety mechanisms, etc. Both structures are supported on a common circular slab.In this paper, an outline of the static and seismic response analyses performed for these buildings is presented. Several computer models and codes are used and advantage is taken of the symmetry of revolution of part of the structure.By combining the results produced by the various models and accounting for discontinuities caused by openings, etc., a complete picture of the forces, displacements, or accelerations existing in the reactor building under operating conditions and during postulated accidents or seismic events may be drawn.This process has been partly automated by the development of relevant software. A flow chart of the whole analysis process is given. Key words: nuclear power plants, reactor building, containment, analysis, static, seismic, finite elements.
Generator inertia for isolated hydropower systems
Authors: Gordon J. L. , Whitman D. H.
Published: January 2010

Speed regulation of hydroelectric power plants of isolated systems is a complex subject, which is now becoming more important as customers install computers, stereophonic equipment, and advanced satellite dish electronic equipment in such systems. This paper presents a methodology for determining hydroelectric generator inertia, based on theoretical analysis, coupled with a review of data from over 50 hydroelectric projects with units having capacities between 2 and 300 MW. The parameters that affect generator inertia—system size, allowable frequency variation, type of load, turbine and governor, water column start time, governor time, and relief valve operation— are all discussed. A chart combining these parameters is developed, on which data from hydro projects is plotted. From an analysis of the plotted data, an empirical equation is developed for the generator inertia as a function of the aforementioned parameters. Key words: hydroelectric power, generator inertia, speed regulation, hydro design.
Le barrage OA-10B, un exemple de construction d'un barrage sur des dépôts d'origine glaciaire
Authors: Massiéra Michel , Pelchat Claude
Published: January 2010

The OA-10B dam is one of the earth structures of the EOL (Eastmain – Opinaca – La Grande) project within the "La Grande" hydroelectric complex at James Bay, in the northwest of Quebec. Three rivers, the Eastmain, Petit Opinaca, and Opinaca, were diverted to the La Grande River to increase the hydropotential of the LG-2 power plant. Dam OA-10B, 25 m high, has a zoned section with an impervious moraine central core, and rests mainly on overburden foundations consisting of heterogeneous deposits of glacial till. The paper describes the different construction phases of the dam with emphasis on foundation treatments. Key words: construction, core trench, dam, dewatering, excavation, foundation, glacial till, instrumentation, moraine, treatment.
Effect of comparative efforts on sand–asphalt–sulphur mixes
Authors: Mazumdar Mayajit , Rao S. K.
Published: January 2010

The investigation studies the effect that varying the compactive effort has on the Marshall test properties of sand–asphalt–sulphur mixes (S–A–S mixes). An S–A–S mix containing a poorly graded river sand has been chosen for study, the proportions of sand, asphalt, and sulphur being 85:5:10 by weight.Another aspect of this study is to examine the effect of fly ash fines, an industrial waste, on S–A–S mixes. The resulting mix is named S–A–FA–S (sand – asphalt – fly ash – sulphur) and has a percentage composition of 80:5:5:10 by weight.It has been observed that the compactive effort has a definite effect on the Marshall test properties of S–A–S and S–A–FA–S mixes. In both cases, the stability rises initially and then falls with increasing compaction. S–A–FA–S mixes give higher stabilities and lesser air void values than S–A–S mixes at a particular level of compaction. It is concluded that 10 blows of compaction is optimum for S–A–S as well as S–A–FA–S mixes, as the beneficial effect after 10 blows is only marginal.
Seepage flow through simulated grounded ice jam
Authors: Wong J. , Beltaos S. , Krishnappan B. G.
Published: January 2010

Laboratory tests were conducted to study the seepage flow conditions through a simulated grounded jam. Results indicated that nonlaminar seepage predominates and that the resulting relationship between the local flow and the upstream and downstream water depths may be applied to both steady and unsteady flow conditions.
Eccentricity in irregular multistory buildings
Authors: Cheung V. W.-T. , Tso W. K.
Published: January 2010

To evaluate the seismic torsional effect on multistory buildings, the concept of eccentricity is extended from single-story buildings to multistory buildings by defining the locations of the centers of rigidity at each floor. A practical procedure to locate the centers of rigidity and hence floor eccentricity is introduced. This procedure depends on the use of plane frame computer programs only and is suitable for use in design offices. The seismic torsional provisions in the National Building Code of Canada 1985 (NBCC 1985) explicitly emphasize that the code provisions apply to buildings where the centres of rigidity lie on a vertical axis only. By means of examples, it verifies the claim of NBCC 1985. Also, it shows that, for buildings with centers of rigidity scattered from a vertical axis, the code procedure may or may not apply. Therefore, one should interpret the condition of centers of rigidity located along a vertical axis to be a sufficient, but not a necessary, condition for the NBCC 85 code provisions to be applicable. Until the necessary conditions are known, dynamic analysis remains the most reliable method to assign the torsional effects to various portions of the building. Key words: building code, center of rigidity, dynamic analysis, eccentricity, irregular, multistory, seismic, torsion.
Behavior of headed shear studs in stub–girder stub assemblages
Authors: Chan T. W. K. , Rezansoff T. , Hosain M. U.
Published: January 2010

The paper summarizes the results of push-off tests conducted on 42 end stub assemblages. Written for conventional composite construction, the current Canadian Standards Association (CSA) standard on stud connectors offers little guidance for stub–girder design. A stud spacing of four times the stud diameter (the CSA requirement) does not appear to be adequate for a full development of the potential shear capacity of a stud connector in the stub–girder system. The required minimum stud spacing appears to be between five and six times the stud diameter for the case of 13 mm studs. Moreover, the CSA-recommended shear capacity of stud connector should be reduced to reflect the effect of prying forces. A modification factor of 0.9 is suggested for a 13 mm diameter stud connector. Test results for specimens with 19 mm studs indicated a further decrease in the shear capacity. However, a definite recommendation is postponed pending further tests.In addition to prying forces, stud configuration and spacing and the amount and location of transverse reinforcement must also be taken into account in determining the shear capacity of a stud connector. For a connection with 13 mm studs arranged in a single row, a reduction factor equal to stud spacing divided by six times the stud diameter is suggested when the stud spacing is less than six times the stud diameter. For a connection with staggered studs, the corresponding factor is obtained by dividing the stud spacing by five times the stud diameter when the stud spacing is less than five times the stud diameter. Key words: headed stud, shear capacity, minimum stud spacing, prying force.
La capacité portante à court terme de la glace de mer colonnaire annuelle
Authors: Murat J. R. , Tinawi R.
Published: January 2010

This paper deals with the bearing capacity of sea ice covers taking into consideration the nonhomogeneity of the material, which is primarily due to variations in temperature and salinity across the thickness. The study is limited to the evaluation of short-term loads that would cause cracking in the ice cover. The general method for evaluation of such loads is fully developed and simplified formulae are proposed for a given surface temperature and ice thickness. Key words: bearing capacity, sea ice.
Wind resistance of a narrow partially built house
Authors: Macnaughton Ronald A.
Published: January 2010

This paper contains a wind load and resistance analysis for a type of structure that has frequently failed: partially built houses. The critical component of such structures is identified to be the first-storey shearwalls running across the house. The calculated racking strength of that storey is compared to the wind loading the structure would be expected to resist if it were engineered. Various methods are proposed for builders to provide these structures with more wind resistance during the early stages of construction. Differences between Canadian codes and codes in other jurisdictions with respect to this are pointed out. Key words: wind loads, houses, failure, wind bracing, temporary bracing, shearwalls, fibreboard, sheathing, permanent bracing, racking strength, construction procedures, nailing, building code.
Three-dimensional stress analysis of tubular joint using rezone technique
Authors: Bhuyan G. S. , Arockiasamy M. , Munaswamy K.
Published: January 2010

This note presents three-dimensional stress analysis results of a welded tubular T-joint under axial loading, using rezone technique. The rezone technique is used to reduce computer storage requirements, as well as solution costs, that result from the large number of degrees-of-freedom associated with three-dimensional analysis of the entire joint using solid elements. The hot-spot region around the weld toe and the weld reinforcement are modelled using three-dimensional incompatible 8-node brick and 6-node prism elements. The boundary nodal displacements for the rezoned model are obtained from plate analysis of the entire joint. The boundary values, at the plate-to-solid element transition zone, are distributed between two solid element nodes maintaining boundary displacement compatibility. The stresses at the critical lines, obtained from the rezoned analysis, are compared with those of the entire three-dimensional and plate model analyses. Key words: tubular joint, rezoned model, transition zone, boundary displacement compatibility, incompatible elements.
Effluent treatment experience at a high-grade uranium mine
Authors: Hynes Thomas P. , Meadley Tim , Thompson Neill
Published: January 2010

Amok Ltd. is the operator of uranium mining and milling facilities at Cluff Lake in northwestern Saskatchewan. All contaminated liquid effluents from these facilities have been subject to treatment by chemical and physical methods before release to the environment. In particular, a secondary treatment system (STS) has been operated adjacent to the tailings management area to reduce the concentration of radium-226 to below the maximum levels allowable in the final effluent. The STS has operated for over 2 years at a nominal rate of 4000 m3/day. During this time, the most stringent regulatory limit on radium-226 concentration (0.37 Bq/L = 10 ×10−12 g/L total, based on a monthly arithmetic mean) has been exceeded on only two occasions. The process regularly removes 99% of the radium from the effluent stream. Data is presented on chemical addition rates, efficiencies of system components, and the significance of each stage of the treatment process. In addition, several modifications have been made to the STS. Recently, a primary treatment system has been added to the effluent treatment process. Preliminary indications are that this system has increased the overall efficiency of the system.
Comment évaluer l'érosion d'une vallée sous l'écoulement de rupture d'un barrage
Authors: Kenfaoui M. , Marche C.
Published: January 2010

This laboratory experimental study deals with dam-break flows on movable beds. It demonstrates significant differences between these wave parameters and values of the same parameters estimated on fixed beds. Moreover it is shown that under specific conditions some sediment transport models for steady flows can be applied to estimate bed erosion for this particular type of flow. Key words: dam, dam-break, break flows, erosion, laboratory tests.