bluuebunny/crossref_metadata_2025 huggingface dataset:
A simultaneous decision-making approach to model the demand for freight transportation
Authors: Abdelwahab W. M. , Sargious M. A.
Published: January 2010

The application of discrete choice models (e.g., logit, probit) to study modal choice in passenger transportation has had a wide acceptance in the literature. However, little success had been reported on the application of these models to study the demand for freight transportation. This is mainly because in freight transportation a model that merely attempts to explain the choice of mode without taking into consideration other related factors, such as shipment size, is only one part of a complete model. Another type of models known as inventory-based models, which takes these factors into consideration, has been developed and applied with a greater success. However, the data requirement of these inventory models has hampered their applicability, especially in situations with limited data on goods movement. This paper presents a new approach to study the demand for intercity freight transportation. The model proposed in this paper utilizes the strength of discrete choice models (e.g., probit) in explaining the process of mode choice as one part of a complete model. The complete model is presented as a joint discrete/continuous choice model for the choices of mode and shipment size. The model is practical in that it requires the same amount and quality of data that would be required to develop a standard disaggregate mode choice model, and it can be estimated using simple two-stage estimation methods which utilizes standard probit maximum likelihood and ordinary least squares estimation techniques. Key words: disaggregate, freight transportation, maximum likelihood, mode, model, probit, shipment.
A design basis tornado
Authors: Newark Michael J.
Published: January 2010

Based on a combination of data from Canadian and U.S. sources, a design basis tornado is proposed for each of the five Fujita-scale categories (F0 to F4) of damage experienced in Canada. The parameters given are median damage length; median damage width; median damage area; maximum rotational speed; average translational speed; dynamic wind pressure; maximum static pressure drop; and the change of static pressure. Key words: design, tornado, structures, wind.
Guidelines for the planning and design of wastewater lagoon systems in cold climates
Authors: Heinke G. W. , Smith D. W. , Finch G. R.
Published: January 2010

Lagoons are the most widely used form of wastewater treatment in Canada, particularly in the western provinces and northern territories. Existing lagoon design guidelines developed for warm climates must be modified for successful use in cold climates. The use of short-detention lagoons followed either by long-detention continuous flow lagoons or by 270 – 365 d storage lagoons will be required in most situations. Under special circumstances, the conversion of small lakes to engineered lagoon – lake systems may be an acceptable option. Detailed guidelines for the planning and design of these types of lagoons are presented with emphasis on the cold regions of Canada. Key words: wastewater, treatment, cold climate, lagoon, design, guidelines.
Period-dependent seismic force reduction factors for short-period structures
Authors: Tso W. K. , Naumoski N.
Published: January 2010

The seismic force reduction factors proposed in the seismic provisions of the National Building Code of Canada 1990 (NBCC 1990) are examined using ground motion records from two recent Canadian earthquakes. The displacement ductility demands are analyzed for structural systems with different ductility capacity. It is found that the NBCC 1990 force reduction factors, which are period independent, lead to a very high ductility demand for short-period structural systems. To avoid this, two types of period-dependent force reduction factors for short-period structures are investigated. The results show that the linearly varying period-dependent reduction factor represents a viable means to resolve the high ductility problems associated with short-period structural systems. Key words: earthquake, seismic, design, code, response, spectra, ductility, reduction factor, base shear.
Influence de l'âge au démoulage et du type de moule sur la résistance à l'écaillage de bétons contenant de la fumée de silice
Authors: Vézina Daniel , Beaupré Denis , Pigeon Michel
Published: January 2010

This paper outlines the findings of laboratory tests to check the influence of curing and type of mould on scaling resistance of three types of concrete exposed to frost and deicing chemicals: a plain concrete and concretes with 5 and 10% silica fume (relative to total binding mass). Sodium chloride was the deicer used for the tests, which were performed according to standard ASTM C672 (Standard test method for scaling resistance of concrete surfaces exposed to deicing chemicals). The tests showed that type of mould (steel or wood) and curing (12 or 48 h) have relatively little influence on scaling resistance of concrete but that silica fume in the concrete can cause a significant drop in scaling resistance. Key words: concrete, silica fume, demolding age, formwork type, scaling resistance, freezing, deicing salt, sodium chloride. [Journal translation]
Utilisation des parois moulées en béton comme rideaux d'étanchéité des fondations de barrages en terre et en enrochement
Authors: Massiéra Michel
Published: January 2010

At La Grande Complex, Quebec, Phase 1, earth and rockfill dams and dykes were constructed, in some cases, on pervious foundations and required deep impervious cutoffs (concrete cast-in-place walls) to bedrock. This paper describes the different construction phases of these concrete cast-in-place walls with emphasis on construction control and special construction problems. Key words: dam, construction, cutoff, excavation, foundations, bentonite, concrete cast-in-place wall, treatment.
Modelling the load–slip behaviour of timber joints with mechanical fasteners
Authors: Erki M. A.
Published: January 2010

An analytical model of behaviour is presented, which uses one-dimensional finite element approximations to predict the short-term load – slip response of a single fastener joint. The model treats the elastoplastic behaviour of the fastener as well as the nonlinear, nonelastic properties of the wood. It accounts for some of the distinctive behaviour of timber joints such as fastener withdrawal, rotational restraint at the fastener ends, joint interface characteristics, and combined fastener bending and axial tension. Good agreement is obtained between model predictions and test behaviour for single fastener glulam rivet, nail, and bolt joints. The model can be adapted to include the variability in wood and fastener properties, and can be incorporated into a large number of computer simulations in order to predict the fifth fractiles of the populations of joint resistances, which can be used in a limit states design approach. Key words: timber structures, glulam rivet connections, nailed connections, bolted connections, mathematical model, finite element, nonlinear analysis.
A continuous design formula for timber columns
Authors: Johns Kenneth C.
Published: January 2010

Timber column design methods have now to take account of a body of research work on timber properties from in-grade tests and on strength considerations using notions of stressed volume. This paper gathers results from this body of work and proposes a design formula for timber columns which is convenient to use and represents true behaviour. It includes, in particular, a material strength effect related to the length of the column. The proposed formula has been incorporated into the new Canadian code “Engineering design in wood.” Key words: timber, buckling, columns, design, size effects.
Reliability of flood discharge estimates
Authors: Quick Michael C.
Published: January 2010

The high accuracy of normal river discharge measurements is contrasted with the approximate methods used to estimate large floods. The most commonly used method, the slope–area method, is examined and it is argued that there is likely to be a strong upward bias in these flood estimates. Sources of error are subdivided into four main types: (i) error in the Manning friction coefficient, (ii) error in after-flood measurements of channel cross section, (iii) estimation of surface slope and energy grade line from high-water marks, and (iv) the effects of erosion and sediment transport. These various factors are seen to be influenced by channel curvature and meandering, floodplain flow and interaction with the main channel, and changes to channel geometry during a flood. From theoretical work on high sediment transport, it is argued that up to one third of the channel slope is required for moving the sediment, so that only two thirds of the slope is available for transporting the water. Key words: floods, river flow, channel friction, sediment transport, floodplains, meandering.
Size effects occurring in defect-free spruce – pine – fir bending specimens
Authors: Madsen Borg , Tomoi M.
Published: January 2010

While it has been established previously that the strengths of commercial timber products containing knots and other natural growth characteristics are greatly influenced by the physical dimensions of the pieces, it has not been established whether the same is the case for defect-free wood. The structural engineer has a choice of many grades of timber available for his designs and it may be argued that these grades form a stepwise progression from the rather weak No. 3 grade through select structural grade and into clear defect-free sawn wood. For efficient design, it is important to have the size effects correctly quantified for the different qualities. This study concentrates on quantifying the size effect at the strong end of the perceived progression of increased strength, the clear defect-free wood. For the bending tests carried out in this study, it was found that the length effect was very pronounced while thickness did not affect strength. A consistent depth effect could not be found. If some depth effect did exist, it would be of second order in importance relative to the length effect. From the tests, it was established that the length effect parameter is unlikely to be less than 0.17 for bending. The work was conducted using the species group spruce–pine–fir, which is the most abundant species group in Canada. The tests add further evidence to the argument that the effect of length must be included in the design process for any material where the strength varies along the length of the member. Key words: size effects, defect-free wood, spruce–pine–fir, adjustment factor, length effect parameter.
Pilot-scale studies of sludge dewatering in a freezing bed
Authors: Martel C. James , Diener Carl J.
Published: January 2010

In 1986, a pilot-scale sludge freezing bed was constructed at the U.S. Army Cold Regions Research and Engineering Laboratory in Hanover, New Hampshire, U.S.A. This bed was operated for the next three years using both anaerobically and aerobically digested sludges. Results indicate that both sludges were effectively dewatered by this process. The maximum depth of sludge frozen during this study was 1.14 m. The final solid contents were 39.3% and 24.5% for anaerobically digested and aerobically digested sludges respectively. The quality of the meltwater from the bed was similar to raw wastewater. The actual depth of sludge frozen and thawed in the bed during each year of operation was very close to that predicted by design models. Operational experience demonstrated the importance of a sand layer at the bottom of the bed for adequate drainage. Also, odors developed when the meltwater was allowed to accumulate in the bed. Odors were not a problem when the meltwater was drained away as quickly as it formed. Both sludges were easily removed with a front-end loader. Key words: sludge freezing bed, freeze–thaw conditioning, freeze–thaw separation, sludge dewatering, freezing bed.
Performance of bridges in the 1989 Loma Prieta earthquake – lessons for Canadian designers
Authors: Mitchell Denis , Tinawi René , Sexsmith Robert G.
Published: January 2010

Damage to buildings and bridges during the October 17, 1989, Loma Prieta earthquake prompted site visits by the authors. This paper first reviews examples of the severe damage and the collapse of bridges in the 1971 San Fernando and 1987 Whittier Narrows earthquakes. The resulting changes to U.S. bridge design codes and the application of different types of restraining devices used to retrofit existing bridges are discussed. Examples of damage and collapse of bridges in the 1989 Loma Prieta earthquake are illustrated. The important roles played by the presence of soft soil, poor structural systems, and inadequate detailing are highlighted. The observed damage is used to illustrate the need to assess the seismic design provisions of the current CSA standard for the design of highway bridges. Concern over the presence of existing hazardous bridges in significant seismic zones in Canada is emphasized and a checklist for evaluating existing bridges is presented. Key words: seismic design, earthquake, evaluation, Loma Prieta, San Fernando, bridges, codes, retrofitting.
Strength tests on slender plain block masonry walls with veneer wythes
Authors: Neis V. V. , Ghosh S. , Hatzinikolas M.
Published: January 2010

An experimental program was undertaken on single wythe and cavity concrete block masonry walls to evaluate the effect of the veneer on the vertical load-carrying capacity of the wall. Twelve unreinforced, ungrouted, and relatively slender single wythe and cavity walls were tested to failure under quasi-static, monotonic, axial loading. Three values of equal end load eccentricity were used in the test program. A review of published test data associated with the behavior of single and double wythe concrete block masonry walls indicates a scarcity of data regarding the magnitude and type of effect of the veneer on the stiffness, strength, and stability of such walls. To examine the performance of axially loaded slender masonry walls, and to isolate any effect of the veneer in modifying that performance, the plain masonry walls of the present program were chosen to be quite slender (height-to-thickness ratio of 30) and relatively thin (thickness = 140 mm). This study used a microcomputer spreadsheet program to evaluate the theoretical capacity of the walls and to generate load –moment interaction diagrams. The program is based on a moment–area analysis and incorporates the effects of finite deflections, nonlinear constitutive laws, and cracked section behavior. The walls exhibited material failure in the case of centrally loaded walls, whereas stability failure governed for eccentrically loaded specimens. The contribution of the veneer to the lateral stiffness of the cavity wall system was found to vary with the eccentricity of the applied end load. The contribution to strength seemed to be negligible for central loading, but was quite significant for the case of the eccentrically loaded walls. More tests covering different loadings, slenderness values, and end conditions are needed to quantify the behavior. Key words: masonry, slenderness, stiffness, stability, capacity, veneer, cavity wall, ties, eccentric loading.
Slenderness effects in high-strength concrete columns
Authors: Lahoud Antoine E.
Published: January 2010

High-strength concretes are being increasingly used in the columns of high-rise buildings. Analytical studies of the slenderness effects in these columns have been very limited. The behavior of slender columns with normal- and high-strength concretes is studied using a finite element program. Differences and similarities in long-term and short-term behaviors between high-strength and normal-strength slender concrete columns are noted and discussed. Key words: columns, slenderness, high-strength concrete, creep, finite elements.
Application of reliability theory to in-service monitoring and maintenance of parking garages
Authors: Attwood Daryl , Nessim Maher A. , Ghoneim Abdel , Cormeau Andre , Cheung Moe S.
Published: January 2010

Reliability, defined as the probability of survival in a given period of time, forms the basis of most design codes. In this work, the use of reliability concepts to make informed decisions regarding in-service monitoring and maintenance is demonstrated. Parking garages are used as an example application. The degradation of the driving surface, as defined by the percentage of floor surface delaminated, was used to describe the deterioration process. The delamination is related to corrosion of the reinforcing steel accelerated by Cl− ions deposited in the concrete lattice from deicing salt laden vehicles. The time at which deterioration commences and the rate at which it proceeds are related to the depth of cover to the top level of the reinforcing steel, the water-to-cement ratio of the concrete, the concentration of Cl− ion in the deicing salt mixture, the treatments used to prevent Cl− ion attack, the crack size, and the garage temperature. A limit-state function relating to the degree of delamination to the garage age and other influencing parameters was developed and used in a first-order reliability method algorithm to evaluate repair intervals and treatments such as polymer impregnation, vacuum treatments, boiled linseed oil, and absorptive form liners. Considerable savings in maintenance costs may be achieved through optimum scheduling and choice of garage surface treatment. Key words: reliability, maintenance, parking garages, monitoring, repair, inspection.
An experimental study of end plate shear connections
Authors: Dalen Karl Van , Dalen Mark Van
Published: January 2010

The shear behaviour of both conventional end plate connections and clipped end plate connections, in which the upper corner of the end plate was removed, was examined in a laboratory investigation of 29 full-scale test specimens. The study included connections of varying geometry, bolt diameter, and end plate depth. The majority of the connections failed in one of two modes: a failure of the bolt group component or a web-tear failure. For connections failing through the bolt group, the ratio of the shear capacity of the clipped connection to that of the conventional connection is the ratio of the number of bolts in the clipped and conventional connections. Even when failure is not through the bolt group, the shear capacity of an end plate connection is reduced when the upper corner of the end plate is clipped. The experimentally determined shear capacities are compared with the calculated resistances determined using the resistance equations in CAN3-S16.1 in conjunction with the assumptions of load transfer mechanisms and stress distributions embodied in the design aid for end plate connections in the Handbook of Steel Construction. Key words: beams, connections, bolts, end plates, shear strength.
The enhanced performance of split-ring connections through prestressing
Authors: Quenneville J. H. P. , Dalen K. Van
Published: January 2010

This paper examines the concept of enhancing the performance of timber connectors in truss joints by the introduction of transverse prestressing. The behaviour of lap splices of Douglas fir, with 63 mm split-ring connectors and end distances of 50, 100, 150, and 210 mm, was examined for various levels of prestress in a laboratory study. As well, the magnitude of the load that can be carried by the connection through friction between faying surfaces was also assessed for various levels of prestress. The simple technique used in the laboratory for introducing prestress is described. Results of the laboratory tests on 20 joint configurations are presented, and the experimentally determined strengths are compared with the calculated resistances using the provisions of CAN\CSA-086.1-M89 "Engineering design in wood (limit states design)." Key words: timber, connector, prestress, truss joint.
Définition des conditions de vagues pour la conception d'un havre de pêche à Sept-îles
Authors: Ouellet Y. , Drouin A.
Published: January 2010

This paper presents the results of numerical studies to define the wave climate inside the Bay of Sept-îles, where it is proposed to build a small craft harbour. This wave climate is relatively complex as it results from waves coming from outside the Bay, that is from the estuary of the St. Lawrence, or generated inside the Bay itself. Such information is required to select the configuration of the harbour and the best location among the various sites proposed. Waves have been recorded at a station outside the Bay in 1966 – 1967 and inside the Bay in 1983. These records were used to calibrate the wave forecasting model based on wind data recorded at Sept-îles airport. They were also used to validate results obtained from a refraction model used to determine wave transformation from outside to inside the Bay. Then waves were forecasted over a long period (1953 – 1984), for the ice-free season, and used to study wave agitation inside different schemes proposed for harbour configuration and site. The study shows that there is a need to obtain better wave information and to improve the numerical models. Key words: wave forecasting, wave transformation, wave records, wave modeling, harbor, Sept-îles.
Utilisation d'un modèle ARMAX pour la prévision du débit à Carillon
Authors: Bennis Saad , Rassam Jean-Claude
Published: January 2010

This paper discusses the use of an ARMAX model to predict the total discharge at the Carillon power plant on the Ottawa River in the province of Quebec. This prediction is used to manage the power plant's headrace canal level during spring floods to reduce flooding in the area between Carillon and Pointe-Gatineau. The Kalman filter recursive algorithm is adapted to the problem discussed and operates in real time to generate 24-h optimal predictions. Two versions of the forecasting model were considered and classified according to complexity and performance. The first forecasting model is an autoregressive model applied to intermediate inputs and assumes that the input of the three main tributaries is known. It does not account for flood routing or transportation delay between the system's input and output. The Nash global factor is 0.91 and 0.86 for flood peaks only. The ARMAX model takes into account flood routing and transportation time that is assumed to be variable. The Nash global factor is 0.97 and 0.95 for flood peaks only. This latter model was therefore selected to manage and predict the Carillon headrace canal level. Key words: ARMAX model, discharge forecasting, Carillon.
Pumping more than 100 m3/min from excavations for open-air amphitheatres in the city of Québec
Authors: Chapuis Robert P. , Keilani Abdel , Cardinal Germain
Published: January 2010

Two agoras, or open-air public amphitheatres, were built during 1982 in the old port of the city of Québec. They are encased in uncontrolled backfill materials which were dumped during the last hundred years as the remodelled wharfs advanced into the St. Lawrence River. Old wooden wharfs were known to have been buried in backfill materials, and thus a large water inflow was expected to occur there and to depend on tide levels. The water inflows through the old wooden wharfs constituted less than 2% of the total infiltration, which reached a rate of 114 m3/min (25 000 gpm) at the highest tide. It was necessary to install a pumping system consisting of twelve 25-cm pumps connected to a collector 91 cm in diameter. The sources of these water inflows were determined with the help of old drawings, boreholes, water tests, and tracer tests. Most pumped water was coming through cobbles and boulders backfilled around a pressure sewer pipe 2.1 m in diameter. This note describes the work carried out to control the exceptional water inflows in order to complete construction within the required time. Key words: construction, dewatering, groundwater.
A note on circular sharp-crested weirs
Authors: Balachandar R. , Sorbo Silvana , Ramamurthy A. S.
Published: January 2010

A simple approach is proposed to determine the discharge coefficient of sharp-crested, thin plate circular weirs. The model developed incorporates the effects of the width of the approach channel and the height of the weir crest above the channel floor on the weir discharge coefficient. The model is verified using experimental data. For the practical range encountered in the field, a simplified equation is also suggested to determine the weir discharge coefficient. Key words: sharp-crested weir, circular control section, discharge coefficient.
A study of the stability of dynamically stable breakwaters
Authors: Hall K. R. , Kao Joseph S.
Published: January 2010

The effect of gradation of armour stones and the amount of rounded stones in the armour on dynamically stable breakwaters was assessed in a two-dimensional wave flume. A total of 52 series of tests were undertaken at the Coastal Engineering Research Laboratory of Queen's University, Kingston, Canada using irregular waves. Profiles of the structure during the various stages of reshaping were measured using a semiautomatic profiler developed for this study. Four gradations of armour stones were used, giving a range in uniformity coefficient of 1.35–5.4. The volume of stones and the initial berm width required for the development of a stable profile, along with the extent to which the toe of the structure progressed seaward, were chosen as representative parameters of the reshaped breakwater. The results indicated that the toe width formed as a result of reshaping and the area of stones required for reshaping were dependent on the gradation of the armour stones. The initial berm width required for reshaping was also found to be dependent on the gradation and the percentage of rounded stones in the armour. Key words: breakwaters, dynamic stability, hydraulic models, stability, armour stones.
Factored axial compressive resistance of schifflerized angles
Authors: Adluri Seshu Madhava Rao , Madugula Murty K. S.
Published: January 2010

The concept of schifflerization of 90° equal-leg angle is presented and its application in triangular-base latticed steel towers is explained. The similarities and differences between schifflerized angles and regular 90° angles are discussed. The current design practice for schifflerized angles is reviewed and its limitation is highlighted. A design method which includes the effect of the torsional-flexural buckling mode of failure is proposed. For ready use of designers, the factored axial compressive resistances of schifflerized angles are tabulated for both the present and proposed design methods. Key words: buckling, compressive resistance, design criteria, schifflerized angles, stability, standards, steel, struts, towers, guyed towers.
Tertiary treatment of municipal wastewater using bioflocculating micro-algae
Authors: Sérodes J. B. , Walsh E. , Goulet O. , Noue J. de la , Lescelleur C.
Published: January 2010

Design criteria of a pilot plant for treating secondary municipal effluents using filamentous, bioflocculating micro-algae were evaluated. Using a sequential batch reactor, the best removal rate of ammonia nitrogen was reached for 25% draw volume; at 20–22 °C, up to four cycles per day could be achieved giving a removal efficiency of approximately 2 g of N per day and per square meter of basin (200 mm deep) with negligible nitrogen residual; increasing the water level by increments of 200 mm (from 200 to 600 mm) increased the N removal efficiency in a way similar to an increase in the number of renewals per day on a 200 mm deep basin. The dominant micro-algae (Chlorhormidium) was heavily influenced by the water temperature. Key words: micro-algae, municipal wastewater, water treatment, ammonia nitrogen, removal rate, removal efficiency.
Combined seismic base shear and torsional loading provisions in the 1990 edition of the National Building Code of Canada
Authors: Chandler A. M.
Published: January 2010

This paper evaluates the earthquake-resistant design provisions of the 1990 edition of the National Building Code of Canada (NBCC 1990) for asymmetric building structures subjected to combined lateral shear and torsional dynamic loadings arising from earthquake base excitation. A detailed parametric study is presented, evaluating the dynamic edge displacement response in the elastic range, for the side of the building which is adversely affected by lateral–torsional coupling. A series of buildings is studied, with realistic ranges of the fundamental natural period, structural eccentricity, and uncoupled frequency ratio. These buildings are evaluated under base loadings arising from a total of 45 strong motion records taken from earthquakes in North America, Mexico, Europe, the Middle East, and Southern Pacific, categorized according to site soil conditions and the ratio a/v of peak ground acceleration to velocity. The latter parameter together with the uncoupled lateral period are found to influence strongly the combined dynamic edge response, with the greatest forces on edge members arising from earthquakes with high a/v ratio in structures with natural periods below 0.8 s. In this case the NBCC 1990 loading provisions significantly underestimate the elastic dynamic response. For buildings with periods longer than 0.8 s, the conservatism of the base shear provisions leads to overestimation of combined dynamic edge response in asymmetric systems, and this is also true in the short-period range for buildings subjected to ground motions with low a/v ratio. The NBCC 1990 provisions are reasonably conservative for short-period systems subjected to ground motions with intermediate a/v ratio. Key words: earthquakes, seismic, design, response, spectra, base, shear, torsional, provisions.
Influence of site amplification of seismic ground motions on forces in building structures
Authors: Heidebrecht A. C. , Henderson P. , Naumoski N. , Pappin J. W.
Published: January 2010

The results for nine sites with different characteristics subjected to earthquakes of varying intensity and frequency content are presented in the form of base shear coefficients, base shear coefficient ratios (surface to rock), and foundation factors. They indicate that large amplifications can be expected at structural periods close to the site periods, especially for low intensity excitation. Comparisons are made with the provisions of the National Building Code of Canada (NBCC) 1990. They show that, depending on the site and the nature and level of the excitation, the expected base shear can be well in excess of the values specified by the NBCC. Key words: seismic, design, code, soil, site, response, amplification, base, shear.
Hydraulics of steeppass fishways
Authors: Rajaratnam N. , Katopodis C.
Published: January 2010

This paper presents the results of an experimental study on the hydraulics of steeppass fishways. Using theoretical considerations and experimental observations, an expression has been developed that relates the flow rate, slope of the fishway, and depth of flow. It was also found that the characteristic (similarity) velocity profile found earlier, for smaller values of depth to width ratio,y0/b, with the maximum velocity near the bottom, changes to a rather symmetrical profile with the maximum velocity occurring somewhere near the mid-depth for larger values of y0/b. A correlation has also been found for the maximum velocity. This paper also includes some observations on the M-type backwater curves that would appear in the fishway when the tailwater depths exceed uniform flow depths. Key words: fishways, hydraulics, turbulent flow, open-channel flow, hydraulic design.
Seismic response of concentrically braced steel frames
Authors: Redwood Richard G. , Lu Feng , Bouchard Gilles , Paultre Patrick
Published: January 2010

Braced frame structures designed according to the 1990 edition of the National Building Code of Canada and the CSA standard for steel structures (CAN/CSA-S16.1-M89) are analyzed under a number of different earthquake motions. The nonlinear response is studied in the light of the design philosophy, and the validity of a number of design assumptions is examined. The study is limited to a group of eight-storey frames, located either in Victoria, British Columbia, or Montreal, Quebec, all with the same bracing configuration. A 20-storey frame in Montreal is also considered. The results suggest a number of areas in which improved design provisions could be made. Key words: analysis, design, structural engineering, steel, earthquakes, braced frames.
Effect of diurnal temperature variation on the hydraulics of clarifiers
Authors: Godo Anna M. , McCorquodale J. A.
Published: January 2010

This study was carried out to obtain data on the behaviour of thermally induced density currents in primary rectangular clarifiers so that better models can be developed for these units. This note deals with the case when the influent is cooler than the ambient temperature in the tank. The experiments were made in a model with a scale of about 1:20 compared to the typical full-scale clarifier. Temperature surveys and dye tests were carried out for turbulent flow and temperature differences between influent and effluent that were equivalent to ±0.2 °C in the prototype on a diurnal basis. The results indicate six flow regimes that follow a decrease in influent temperature: (i) denser wall jet; (ii) splash at the end wall; (iii) moving internal hydraulic jump; (iv) submerged internal hydraulic jump; (v) splash at the influent baffle; and (vi) stratified flow. A comparison of the test data with those available in the literature showed that the entrainment equations involving the Richardson number are adequate for modelling, but the classical hydraulic jump equations need modifications for the effect of entrainment. Key words: clarifiers, rectangular, primary, model, density currents, internal hydraulic jumps, unsteady flow, denser wall jets.
Spatial distribution of peak cladding loads on tall buildings
Authors: Ho T. C. E. , Surry D. , Davenport A. G.
Published: January 2010

Wind tunnel tests on building models show that the patterns of cladding pressures are complex and varied. Their reliable representation, in a simple form, for building codes and standards presents a difficult conundrum. Necessarily, code descriptions need to be defined in terms of a few well-chosen parameters. In this paper, an approach is described which answers some of these difficulties. In essence, the actual pressure distributions from a wide variety of building shapes are broken down into systematic patterns of pressures which are inherent in all the distributions. These patterns can be found mathematically from the correlations of pressures at points across the surface. Pressure patterns on individual buildings can be reconstituted by combining these patterns in the right proportions. The proportions vary from building to building in a statistical manner. The important part of the pressure distributions is contained in the fundamental or simplest pattern; the more complicated higher-order patterns "fine tune" the pressure distribution. This hierarchy of patterns provides a logical basis for simplification (by truncation) and appropriate statistical treatment of the uncertainty. An application to the National Building Code of Canada suggests that the results described by the empirical procedures are very reasonable. Further, edge strips of higher pressure are not as statistically significant as first supposed. Key words: wind, tall buildings, local loads, code, statistics, orthogonal functions, variability, reliability.
Behaviour of perfobond rib shear connectors in composite beams: full-size tests
Authors: Oguejiofor E. C. , Hosain M. U.
Published: January 2010

This paper presents the results of six full-size composite beam specimens tested as part of an ongoing research program at the University of Saskatchewan to determine the feasibility of using a new type of shear connector called perfobond rib in composite floor systems. This connector is a flat steel plate with a number of holes punched through. In half of the test specimens, headed stud connectors were used, while in the other half, perfobond rib connectors were used. The results obtained indicate that the perfobond rib connector is a viable alternative to the headed studs. Specimens with four perfobond rib shear connectors performed as well as those with 24 headed studs. The experimentally determined ultimate flexural capacity of the test specimens agreed reasonably well with the predicted values. Key words: composite beam, shear connector, perfobond rib connector, headed stud.
Updating of parameters in aggregate total demand models
Authors: Kumarage A. S. , Wirasinghe S. C.
Published: January 2010

Research on demand-model transferability has consistently shown that the updated models perform better than the simple transfer of the original model with the original coefficients. Several methods are available for the updating of parameter estimates during model transfer. The scalar factor method has been extended to specify individual factors for each variable. This method allows the flexibility of removing insignificant variables in transfer; it also permits the grouping of parameters that have to be updated by a common factor. Individual scalar factors can also be identified for variables that are uniquely affected during transfer. This approach therefore incorporates the strength of both the sample data and the calibration model to its maximum showing that this method gives excellent fit to observed flows when tested for geographical transferability of an aggregate intercity total demand model for public transport in Sri Lanka. It is also shown that the Bayesian method becomes less efficient when sample sizes available for updating become smaller. Key words: travel, demand model, updating, transferability, Sri Lanka.
An expert assistant for selecting green splits, cycle times, and phasing schemes based on the Canadian Capacity Guide procedures
Authors: Stewart J. Allen , Van Aerde Michel
Published: January 2010

The determination of the optimum phase scheme, cycle time, and green split for an isolated traffic signal is usually a very tedious and time-consuming activity. Several computer packages, such as the Micro-Sintral program, have been developed to assist in such situations by automating many of the calculations for a given set of inputs. Unfortunately, the inputs are often equally difficult to determine, and as they may depend upon the ultimate outcome of the optimization process, several time-consuming iterations, during which new input values must be calculated, are required. This paper presents a program called Signal Expert which automates the above iterations and therefore greatly reduces the traffic engineer's efforts in generating a new signal timing plan based on the rather sophisticated procedures that are outlined in the Canadian Capacity Guide. The benefits of applying this new program are illustrated and discussed using the example intersections that are analyzed in the Canadian Capacity Guide and in the Micro-Sintral User's Manual. Key words: isolated intersections, capacity, delay.
Bridge dynamics and dynamic amplification factors — a review of analytical and experimental findings
Authors: Paultre Patrick , Chaallal Omar , Proulx Jean
Published: January 2010

The dynamic amplification factor (DAF) is an important parameter in the design of highway bridges and yet no worldwide consensus has been reached so far as to its value. Some disagreement exists between provisions of various national bridge codes. This is because the DAF depends, in addition to the maximum span or the natural frequency, on many other parameters that are difficult to take into account with reasonable accuracy. Vehicle speed, weight, and dynamic characteristics, the state of the structure, roadway roughness, expansion joints, the type of bridge supports, soil–structure interaction, and influence of secondary elements are some aspects influencing the DAF. This study reviews the analytical and experimental findings on bridge dynamics and the evaluation of the DAF. Key words: bridges, vibrations, bridge testing, bridge design codes, dynamic amplification factor.
Adaptation of CONTRAM to the modelling of temporal distribution of traffic demand
Authors: Allam Shane P. R. , Alfa Attahiru Sule
Published: January 2010

This research investigates the feasibility of adapting CONTRAM to the problem of determining the temporal distribution of traffic demand in an urban transport network. It combines CONTRAM with a second model which determines departure time selection as a function of the output of CONTRAM. The two worked iteratively together. The research considères the single-origin destination and the more realistic network with multiple origins and destinations and multiple routes. The resulting behaviours of demand and of traffic in the system were compared for a variety of changes to base networks. Although some of the single origin–destination pair networks reached an equilibrium solution, demand for the multiple origin–destination problem never converged and showed variations from iteration to iteration within a band. Comparisons of the results of average demand distributions showed that CONTRAM could be applied to this problem, and used to compare alternative network plans for the multiple origin–destination problem, as it provided reasonable and logical results. CONTRAM permits the modelling of a maximum of 13 time intervals. Therefore, as the time frame of study increases, a coarser approximation of continuous demand will result, and will limit the application. Key words: peak traffic, CONTRAM, flexible work times, demand.
Alternative energy substrates for bacterial leaching of heavy metals from sewage sludge
Authors: Couillard Denis , Zhu Shucai
Published: January 2010

Bacterial leaching of heavy metals from sewage sludge with different iron containing compounds as energy substrates was studied in a batch system using a culture of Thiobacillus ferrooxidans. It was proven that spent FeSO4∙7H2O and pyrite met the criteria of an energy substrate and could be substituted for reagent grade FeSO4∙7H2O. This substitution could significantly reduce energy substrate cost: 99% with spent FeSO4∙7H2O and 94% with pyrite. The solid aspect of pyrite compromises its use. Key words: energy substrate, bioleaching, heavy metals, solubilization, Thiobacillus ferrooxidans, sewage sludge.
Mathematical modelling of a circular clarifier
Authors: Zhou Siping , McCorquodale J. A.
Published: January 2010

A numerical model has been developed to predict the velocity distribution and the concentration distribution for a nonuniform flocculated particle suspension for turbulent density stratified flow in secondary clarifiers. This model consists of a set of conservation equations for fluid mass and momentum and sediment concentration as well as a relationship for solids settling velocity. The turbulent stresses are calculated using the eddy-viscosity concept and the k-ε turbulence model. Since the strong local numerical instabilities near the reaction baffle lip, where the low-solids concentration surface return flow joins the high solids concentration bottom current, was successfully overcome in the iterative solution procedure, the calculation zone in this investigation can be extended to take into account the inlet zone of the clarifier. The model gave a satisfactory description of the influence of the density variations on the hydraulic regime and the solids concentration distribution in the clarifier. A good agreement was obtained between the experimental data and the numerical simulation. Key words: clarifier, numerical model, density stratification, turbulence.
Thin unreinforced concrete house foundation walls
Authors: Dozzi P. , Warwaruk J. , Laviolette B.
Published: January 2010

The objective of this study was to determine the feasibility of building residential basement foundation walls of unreinforced concrete thinner than the conventional 200 mm thick wall. The thin-wall foundation should require no special engineering attention, and should be acceptable as a standard to the industry.The study comprised a literature search, building code review, and a feasibility analysis which included technical and cost considerations. Additionally, an industry perspective was obtained through interviews with house builders and contractors specializing in residential basement work.Key issues were determined to be strength, quality control, construction methods and tolerances, cost savings, and market acceptance. As thickness decreases, strength is sacrificed, and the negative effect of axial eccentricity increases, particularly for foundation walls supporting brick veneer. Quality control, particularly in respect of concrete strength and water-to-cement ratios, is important from the perspective of maintaining bending capacities. Some construction methods, for example, cast-in-place joist or the use of nailing ladders, make pouring concrete more difficult in thinner walls. Cost savings and market acceptance are linked, and though costs can be reduced, it may be difficult to influence buyers to break from the traditional 200 mm wall in favour of a thinner one.Consideration of the issues led to the determination of 150 mm as the optimum reduced thickness for an unreinforced 2400 mm high foundation wall. A basement wall of 150 mm thickness and 20 MPa concrete strength supporting a house with brick veneer would be capable of retaining 1500 mm of backfill material. The same wall supporting a house without brick veneer would be capable of retaining 1800 mm of backfill. The cost of the 150 mm thick wall would be in the order of $600 less than that of the conventional 200 mm wall, and those savings could be passed on to the consumer.Technical analysis was based on equivalent fluid pressures and indicated that the 150 mm foundation wall would be suitable for use with clean sand and gravel backfill material. For walls backfilled with soils other than clean sand and gravel, it was found that the theoretical maximum backfill heights for both 150 and 200 mm walls are substantially less than those presently specified in Table 9.15.4.A of the National Building Code. The practice of backfilling with stable native soils (which are characterized by significantly higher equivalent fluid pressures) is common and house foundations have performed well under those conditions. The study therefore concluded that either the accepted values for equivalent fluid pressures or the assumed triangular distribution of lateral soil pressures are in question. Key words: foundations, concrete, residential buildings, houses, soil pressures, lateral pressures, unreinforced concrete walls.
Performance monitoring of pavement test sections
Authors: Hajek Jerry , Joseph Ponniah
Published: January 2010

Pavement engineers are often faced with the need to evaluate field performance of new or alternative pavement materials and construction techniques, as well as rehabilitation and maintenance treatments. This paper provides guidelines for the performance evaluation of pavement test sections and presents an overview of recent developments in the pavement evaluation technology in Ontario. Where possible, actual evaluation procedures are described and results are discussed. The performance evaluation parameters discussed include pavement roughness, surface defects, subsurface defects, wheel track rutting, structural strength, skid resistance, light reflectivity, and noise generation potential of surface texture. The degree of effort and detail with which performance parameters are evaluated should reflect the objective of each test section. The evaluation should be comprehensive and include all relevant pavement performance parameters. Key words: pavement performance evaluation, test sections, roughness, rutting, strength, surface texture.