bluuebunny/crossref_metadata_2025 huggingface dataset:
Interactive graphics in structural analysis
Authors: Humar J. L.
Published: January 2010

Interactive computer graphics which implies a continuous exchange of information between the computer and the user has emerged as a very powerful tool in engineering applications. Computer-aided design (CAD) and computer-aided manufacturing (CAM) have found use in electronic circuit design, manufacturing, mapping, and architectural and engineering planning. Using CAD, a machine part, an electric circuit, or a building plan can be drawn and displayed on a video terminal. The product or plan can then be manipulated, rotated, viewed from different angles, or separated into segments. The graphic and attribute information related to the drawing is stored in a data base, and can be retrieved and modified at any time. At a more sophisticated level of CAD, the data base is used to generate input data for a finite element or another analysis program. This paper presents a brief survey of the CAD scene and the hardware and software available and describes the use of interactive graphics in generating data input for analysis.
The strength of stud shear connectors at low temperatures
Authors: Dalen Karl Van
Published: January 2010

The effect of temperature on the ultimate strength of shear connections consisting of headed stud shear connectors embedded in a normal weight concrete slab is examined by means of pushout tests conducted at temperatures of +20, −10, and −20 °C. The strength of the shear connection with 13 mm diameter studs was found to be lower at −20 °C than at room temperature, whereas the strength of the shear connection with 19 mm diameter studs was found to be greater at −20 °C than at room temperature. This is explained in terms of increased concrete strength and reduced stud strength with decreased temperature, causing a change in the mode of failure. Keywords: composite construction, shear strength, shear connection, stud shear connectors, low temperature pushout tests.
Detention time—A key decision factor in controlling algal blooms in man-made lakes
Authors: Mulamoottil G. , McBean E.
Published: January 2010

The mechanics by which algal blooms occur are examined and from these, a set of factors is identified that are important in modifying bloom conditions. The role of the detention time, one of the key controlling conditions, is examined as it relates to field observations of the presence of different kinds of algal biomass. A case study test of the detention time for a stormwater pond demonstrates the failure of existing design practice to adhere to the detention time criterion, suggesting that algal blooms might well occur in the impoundment.
Strength interactions of finger joints and truss plate joints in light wood trusses
Authors: Keenan F. J. , Dubelsten P. , Klajnerman T. , Kyokong B.
Published: January 2010

This study examined two questionable aspects of using truss plates together with finger-joined wood truss members, namely the possible strength reductions in either the truss plate joint or the member. The lumber was kiln-dried No. 2 grade spruce–pine–fir. The finger joints were "horizontal" and glued with a phenol resorcinol adhesive. Project A dealt with the strength of truss plate joints; in this project, truss plate joints were tested in tension on both faces of 38 × 64 mm lumber and on the 89 mm face of 38 × 89 mm lumber, and both parallel and perpendicular to grain loading. Project B examined the effect of truss plates on the tensile and flexural strengths of finger-joined lumber. Specimens waisted to 38 × 38 mm containing truss plates pressed into both faces of the finger joints were tested in tension parallel to grain, whereas specimens of 38 × 89 mm also containing plates in both faces were tested in bending about both weak and strong axes.The statistical analysis indicated no reduction in strength for the ten-replication tests in both projects A and B. However, the test results suggest that there is a possible inherent weakness associated with the plug-shear failures in project A and the failures at the last row of the plate teeth in project B. The implications of these results on the design of truss plate joints have been adopted by the CSA Technical Committee on Engineering Design in Wood.
Coupure d'un canal de dérivation provisoire
Authors: Rohan Karol
Published: January 2010

A procedure for closure of a diversion channel is presented taking into account previous studies of the author on river closure. The discharge and the diameters of stones to be dumped are determined approximately by computation in order to assure an economically justifiable closure. An experimental correction is needed to achieve a reasonable rate of loss of stone material for dumping.
Improved classification of Canadian primary highways according to type of road use
Authors: Sharma Satish C.
Published: January 2010

An improved method of road classification is suggested for use by provincial or state highway agencies. The proposed classification is based on temporal volume variations and road use characteristics, such as trip purpose, and trip length distribution. The primary highway system of the province of Alberta, Canada, is investigated for the purpose of this study.The proposed method is more objective, comprehensive, and statistically credible than the existing methods. It involves the application of such standard computational and statistical techniques as (i) hierarchical grouping, and (ii) Scheffe's S-method of multiple group comparisons. The analysis presented in this paper is expected to provide highway agencies with a better understanding of individual routes in their road network systems. The proposed method has implications for a standard classification of roads on a provincial and national basis. Such a classification can hopefully lead to an overall consistency in planning and design of roads for both economic and safety purposes. Keywords: roads; road classification; road use; temporal volume variations; traffic counters; traffic volume; trip purpose; transportation.
Selection criteria for slurry trench cutoffs
Authors: Haug M. D. , Kozicki Paul
Published: January 2010

Slurry trench cutoff walls have been employed for over three decades and are becoming increasingly popular for controlling seepage of groundwater and hazardous wastes. They are also gaining acceptance for construction of underground facilities. The technique involves the excavation of a narrow trench in the presence of a bentonitic fluid or slurry. The slurry acts to support the open trench until it is backfilled with an impermeable material. The increase in popularity of these walls has been aided by the development of new construction techniques. These techniques offer the designer a wide range of engineering properties for the cutoff wall. However, there are few published guidelines on the selection of slurry trench cutoffs. This has resulted in situations where the cutoff wall selected was originally designed for a totally different application. The net effect in these cases has been poor performance and an unsatisfactory cutoff wall.This paper examines the principal methods of constructing slurry trench cutoffs, establishes their engineering characteristics, and presents a procedure for selecting a slurry trench cutoff. The factors which influence the selection are identified and discussed. The methodology of the selection process is reviewed with an example. This review and examination of the selection procedure demonstrates that it is an effective method of compiling and systematically analyzing the relevant factors affecting selection of slurry trench cutoffs.
Ice jams in shallow rivers with floodplain flow
Authors: Calkins Darryl J.
Published: January 2010

The equilibrium ice jam thickness given by Pariset et al. is modified to yield a clearer, consistent relationship between the flow hydraulics and thickness. The modified equations are analyzed with respect to a floating ice jam in the main channel with flow also occurring in the floodplain. The final derivation allows the expected ice jam thickness to be computed, given the bed and ice cover roughness coefficients, the channel characteristics, the water surface gradient, and the pre-breakup channel ice cover thickness. The analytical computation for the ice jam thicknesses is compared with prototype data on ice jam thicknesses from four shallow rivers which had significant floodplain flow with the ice jam event. A reasonable correlation between the predicted and measured ice jam thicknesses was obtained. The data suggests that once bankfull depth is exceeded the ice jam thickness does not increase appreciably because of flow diversion to the floodplain. Field measurements of the thickness of the remaining ice jam shear wall along with actual measurements of the ice jam thickness showed a close correlation between the two sets of data.
Transverse reinforcement effect on cracking behaviour of R.C. members
Authors: Rizkalla S. H. , Hwang L. S. , Shahawi M. El
Published: January 2010

Two extensive and independent experimental programs have been conducted to study the cracking behaviour of reinforced concrete members subjected to pure tension in the presence of transverse reinforcement. The first program involved the testing of eighteen reinforced concrete segments and was mainly designed to examine the applicability of the existing equations for predicting crack spacings and widths. The segments were reinforced in two directions and loaded in uniaxial tension beyond the yield stress of the steel. The measured average values of the final crack spacings were compared to the values presented by other researchers. Based on this comparison, a simplified and refined expression for prediction of crack spacing is proposed.The second experimental program involved the testing of sixteen reinforced concrete segments, which were divided into two groups with different concrete covers. Within each group, all segments were identical in all parameters, except the spacing of transverse reinforcement. The program was designed to study the influence of transverse reinforcement spacing on crack behaviour. A methodology including proposed expression for predicting the crack spacing in reinforced concrete members subjected to axial tension with variable transverse reinforcement spacing is presented. Keywords: cracking, crack spacing, crack width, membrane forces, reinforced concrete, tension, transverse reinforcement.
Effect of vehicle eccentricity on longitudinal moments in bridges
Authors: Bakht Baidar , Jaeger Leslie G.
Published: January 2010

The transverse distance of a vehicle from the longitudinal free edge of a bridge has a significant effect on governing longitudinal moments in the bridge. The OHBDC and AASHTO simplified methods are based on an assumed fixed value of this vehicle edge distance. This value, of necessity, is smaller than encountered in most cases, and therefore leads to unnecessarily conservative estimates of live-load longitudinal moments.A parameter is developed to characterize the effect of vehicle edge distance and edge beams. Using this characterizing parameter a graphical method is developed with the aid of which account can be taken of increasing the vehicle edge distance above the value assumed in the AASHTO and Ontario methods. The use of the method is illustrated by means of an example, and the validity of the method is confirmed from field test results.
A la recherche d'un béton de 150 MPa
Authors: Bedard Claude , Aitcin Pierre-Claude
Published: January 2010

It is possible to make in 1983 a field concrete in the Montreal area having a 28-day compressive strength of 120 MPa, using locally available materials.To obtain such a high compressive-strength concrete, it has been necessary to study the overall performances of 8 different cements, 3 types of sand, 16 types of aggregates, 3 types of superplasticizers, 9 grain-size distributions of the coarse aggregate, and 5 different ways of batching. An ultra high strength concrete is not obtained by chance, but through a long research effort planned in a laboratory as well as in the field.Such a concrete is feasible using: (1) high cement dosage of type 10, 20, or 30, according to the desired rate of compressive strength development; (2) a cubical coarse aggregate having a high compressive strength and an elastic modulus as near as possible as that of the mortar; (3) a manufactured sand having a high fineness modulus made from the same rock as the coarse aggregate; (4) a very high dosage of superplasticizer; and (5) 5 to 8% of condensed silica fume. The limited efficiency of the present industrial mixers (tilt mixers) for the very special mixes of this study is actually the main limitation for reaching a strength of 150 MPa. Keywords: high compressive strength concrete, superplasticizer, condensed silica fumes, manufactured sand, grain-sizes, aggregates, retarder, ready-mix concrete, precast plants.
Stochastic analysis of high flows generated by mixed processes
Authors: Waylen Peter R. , Woo Ming-ko
Published: January 2010

Existing stochastic models describing the probability distributions of the magnitude, duration, frequency, and timing of high flows resulting from a single flood-generating process are expanded to accommodate the more generalized case of mixed-generating processes. The proposed method is simple to apply and retains a theoretical and physical basis. The ability to predict high flows at any higher truncation level of interest without resorting to reanalysis of the historical data is presented. The methodology is applied to three basins in southwestern British Columbia that experience both snowmelt and rainfall generated floods. Good agreement between the data derived for the partial duration series of the study basins and the predicted distributions illustrates the general applicability of the technique.
Use of measured imperfections to predict the buckling of axially loaded cylindrical shells
Authors: Pinkney R. B. , Stephens M. J. , Murray D. W. , Kulak G. L.
Published: January 2010

Analyses to predict inelastic buckling of axially loaded thin cylindrical shells are carried out using the finite element technique. The analyses use a bilinear elastic–perfectly plastic material response based upon the associated flow rule of plasticity. Nonlinear geometric effects, combined with initial imperfections, produce load-deflection curves with descending branches for which the limit points are imperfection sensitive.Results from these analyses are compared with two tests of axially loaded cylinders fabricated from 10-gauge (3.4-mm) and 5-mm plate and approximately 1525 mm in diameter. These tests were carried out in the Structural Engineering Laboratory at the University of Alberta. A rational technique for using measured imperfections to obtain effective initial imperfections for use in the analyses is investigated, and is shown to result in accurate predictions of ultimate load. Keywords: shell, cylinder, buckling, plastic, imperfection, axial load, finite element, nonlinear analysis.
Engineering applications of new probabilistic seismic ground-motion maps of Canada
Authors: Heidebrecht A. C. , Basham P. W. , Rainer J. H. , Berry M. J.
Published: January 2010

New peak horizontal acceleration and velocity zoning maps with a probability of exceedance of 10% in 50 years and seven seismic zones are developed from new probabilistic strong seismic ground-motion estimates for replacement of the 1970 seismic zoning map in the National Building Code of Canada. The adoption of a probability of exceedance of 10% in 50 years produces reference seismic ground motion appropriate to the level of protection afforded by provisions of the current code; the use of two ground-motion parameters, the relative levels of which vary considerably throughout the country, provides independent reference levels for structures having short and long fundamental periods.For calculating seismic base shear, a new seismic response factor is derived in which seismic forces for long-period structures are directly proportional to zonal velocities, and for short-period structures proportional to zonal accelerations, with an upper limit on the acceleration/velocity ratio applicable for any location. To maintain the same design standard as provided by the current code, the base shear is calibrated to remain the same, on average, in large population centres in regions of moderate to high seismic risk. The resulting changes in the base shear applicable at various locations reflect the improved estimates of seismic risk, in particular the introduction of additional zones in the higher risk regions of the country and the higher levels of short-period ground motion estimated for some regions of eastern Canada.These and associated changes in seismic design provisions have been recommended for adoption in the 1985 edition of the National Building Code of Canada.
Etude en modèle réduit du problème de franchissement des vagues au quai de Chandler, Baie des Chaleurs, Québec
Authors: Ouellet Yvon , Drouin Marc
Published: January 2010

Wave overtopping can be tolerated in order to reduce the crest height of a structure and consequently its cost. However, if the rate of overtopping becomes too important, the resulting damage incurred on the lee side may become a problem, which has to be overcome by the addition of an appropriate structure to reduce these effects. That is what is happening at Chandler in Gaspé, Quebec, where the wharf was damaged many times, owing to wave overtopping since its construction between the years 1967 and 1971. Different ways to solve the problem have been tried without much success. A scale-model study has been carried out in order to examine the importance of this phenomenon and to compare the efficiency of different solutions suggested to attenuate its destructive effects without reducing the stability of the armor protection.Wave overtopping can be tolerated in order to reduce the crest height of a structure and consequently its cost. However, if the rate of overtopping becomes too important, the resulting damage incurred on the lee side may become a problem, which has to be overcome by the addition of an appropriate structure to reduce these effects. That is what is happening at Chandler in Gaspé, Quebec, where the wharf was damaged many times, owing to wave overtopping since its construction between the years 1967 and 1971. Different ways to solve the problem have been tried without much success. A scale-model study has been carried out in order to examine the importance of this phenomenon and to compare the efficiency of different solutions suggested to attenuate its destructive effects without reducing the stability of the armor protection.
Recent developments in timber engineering
Authors: Madsen Borg , Sexsmith Robert
Published: January 2010

Wood is one of the world's most commonly used structural materials, but structural engineers do not become involved with it as often as with steel and concrete. They can, however, do so on a major scale, as there are very important structures of engineered wood. Structural design in wood is therefore of interest to designers; it is covered by several design standards and is the subject of research in many universities and government sponsored institutions in Canada and elsewhere.This discussion is directed to practicing design engineers seeking knowledge regarding structural design and behaviour in wood but who are not deeply involved with research or code development. It is intended as an up-date to illustrate the role of wood in structures, recent improvements in understanding its behaviour, and trends in design standards as they move to the limit states design format.
An anti-scour system for drilling rigs using airlift
Authors: Murphy D. F. , Yan H. T.
Published: January 2010

An anti-scour system for drilling rigs using airlift designed to sink the spud-cans beyond the reach of scour was pioneered by the authors for the Orion Gulftide in 1977. Since then, a number of drilling rigs have been outfitted with such an anti-scour airlift system, the latest of these being the Glomar Labrador in 1983. To date the system has worked successfully in every case.The difficulties experienced with earlier anti-scour systems, such as fabric nets and sandbag islands, are briefly described.Early experiments with the airlift system as an instrument for underwater excavation and the technical advancements developed by the authors and their engineering basis are expounded in this paper. Keywords: drilling rig, anti-scour system, airlift, underwater excavation, spud-can, engineering basis.
Restoration of concrete snowsheds in Glacier National Park, British Columbia
Authors: Rodway L. E.
Published: January 2010

During the spring of 1979 concrete cracking was noted in a number of the columns comprising a portion of five separate snowsheds protecting the Trans-Canada Highway in Glacier National Park, B.C. and specifically near the summit at Rogers Pass, B.C.The problem was identified as the corrosion of reinforcing steel in the columns due to the action of deicing salts that had been used to assist in the clearance of ice and snow from the highway surface during the annual battles to keep the Pass open year round to vehicular traffic.Recommended remedial measures included removal of the cracked cover concrete, cleaning of the exposed reinforcing steel, application of an epoxy bonding agent, patching with polymer concrete mortar, and finishing with an epoxy sealer.The repair work was begun and completed in the spring of 1980. It was discovered that these remedial measures had been carried out in time to prevent significant destruction of the load-carrying capacity of the columns.After 2 years' service, the repairs were inspected in the summer of 1982. The repaired columns had performed satisfactorily. Continuing distress of nontreated columns was noted and a continuing repair program was recommended. Key words: calcium chloride, column repair, corrosion, cover, deicing salts, durability, electrolytic action, expoxy, patching, polymer mortar, restoration.
A strategy for multiprofessional design of buildings
Authors: Manning Peter
Published: January 2010

The conventional way by which buildings are designed is for the specialist members of design teams (structural, mechanical, electrical, and other engineers, acousticians, and others) to develop in detail the comprehensive concepts of generalists. Thus, architects first develop overall scheme designs, after which consultant engineers and others develop specific subdesigns for the structures, mechanical systems, lighting, and so on that will make that particular overall scheme work. There are some important objections to this kind of process, not the least the handicap that is thus placed upon the input of the engineering and other consultants. A "three-axis design strategy" by which, from the earliest stages of a design problem, solutions are built up from the best common compatible options of all the contributing consultants is described. Key words: building design, systematic design methods, design strategy, multiprofessional, integration, design process, design decisions.
St. John's Harbour water quality model
Authors: Dewey Raymond J. , Palmer Merv D.
Published: January 2010

A dynamic two-dimensional numerical water quality model was developed for St. John's Harbour, Newfoundland, to assist in providing direction for a water quality enhancement program. The model input parameters were adjusted until the model outputs of water levels, currents, and water quality concentrations matched collected field data which included measurements of the sewer discharges. The tidal stage for the most degraded harbour water quality was identified. This stage was used to compare the harbour water quality enhancements and degradations for different management scenarios which included combining and relocating discharges, partial treatment of some discharges, and some direct ocean discharge. By using the model in a comparative manner, the requirements for model verification are reduced as are some of the errors in the modelling process. Key words: St. John's Harbour, dynamic numerical water quality model.
Uniaxial compressive strength of first-year and multi-year sea ice
Authors: Sinha N. K.
Published: January 2010

Strain-rate and stress-rate sensitivity of the compressive strength of first-year columnar-grained ice, first-year congealed frazil ice, and columnar-grained ice from an old floe have been investigated with load applied in the horizontal plane. In spite of similar salinity and density, the frazil ice proved to be considerably stronger than the columnar-grained ice. The strength of porous old floe ice with columnar-grained structure was very much the same as that of first-year ice of similar structure, but the clear bulk ice of the old floe was strongest. Rate sensitivity of strength for the three types of saline ice was similar to that of fresh-water ice. Ductility of the old clear ice (as measured by the strain at upper yield) was the same as that of fresh-water ice; ductility of porous old ice was comparable to that of new frazil ice. New columnar-grained ice proved to be the most ductile material. Key words: columnar-grained, compressive strength, ductility, first-year, frazil, multi-year, rate sensitivity, sea ice.
The transportation of hazardous products in pipelines through urban areas
Authors: Allman R. J.
Published: January 2010

The pipeline – urban encroachment problem is a growing phenomenon in Canada, and the transportation of high vapour pressure liquid petroleum and other hazardous products has added a new dimension to public safety. While pipelines are the safest means of transporting such products, the incidence of damage to these pipelines by outside forces is increasing primarily because of additional activities around them. The problem is being studied by various regulatory agencies, planning groups, and the pipeline industry itself, and encouraging progress is being made. Some of the developments taking place include transportation and utility corridors, innovative land-use planning, legislation to reduce damage by outside forces, upgraded pipeline standards and new technology, one-call systems for locating underground facilities, and an integrated approach toward establishment of emergency contingency plans. Key words: hazardous products pipelines, urban encroachment, transportation corridors, pipeline standards, pipeline legislation, pipeline leak detection, one-call system.
A simple absorber for walking vibrations
Authors: Allen D. E. , Pernica G.
Published: January 2010

One of the most effective ways of improving walking vibration in an existing long-span floor structure is to increase damping by adding one or more vibration absorbers to the floor structure. This note describes the principles involved and how to apply a simple plank absorber, based on experience with a test floor structure at the Division of Building Research, National Research Council of Canada.
The design of armour systems for the protection of rubble mound breakwaters
Authors: Baird W. F. , Hall K. R.
Published: January 2010

A summary of the various forms of armour systems that have been employed since the early 1800's to protect rubble mound breakwaters from wave attack is presented. The design and performance of these protection systems are reviewed. It is noted that design procedures published in recent years have severe limitations and that their use may have led to damage of many breakwaters. Improved or alternative design procedures for armour protection systems that overcome some of these limitations are outlined.
Evolving data processing environment for computational hydraulics systems
Authors: James William , Unal Ali
Published: January 2010

Computational systems in civil engineering hydraulics and hydrology include both process dedicated situations and modelling. Applications include: data acquisition, management, archiving, and presentation; application programs in areas such as meteorology, hydrology, hydraulics, water quality modelling, fluid mechanics, and coastal and ocean engineering; program maintenance and support; documentation and text processing; and real-time control.Hardware and software systems are undergoing rapid development in all these areas. Emerging techniques make it possible to supplant event modelling, and its associated design storm methodology, with more rational continuous modelling, using Atmospheric Environment Services archives, statistical processing of output, and graphics input/output. Continuous modelling, however, leads to data management difficulties. Special software for time series management is essential.Sophisticated data base management systems and local area networks permit improved cost performance. The paper reviews some of these developments and discusses the inevitable evolution of distributed data processing using multi-microcomputer-based data management systems for civil engineering computational hydraulics and hydrology. For concurrent process control and modelling, the authors recommend a local area network of desk-top microcomputers, each assigned individual hydrological modules, communicating with a central hard disk boss microcomputer. Some specifications are suggested. Key words: computational hydrology, computational hydraulics, microcomputer systems, data base management, local area networks, time series management, emerging computer techniques.
Behaviour of compacted fine-grained soil in a brine environment
Authors: Ridley K. J. D. , Bewtra J. K. , McCorquodale J. A.
Published: January 2010

The hydraulic conductivity and engineering properties of compacted fine-grained soils change with time when exposed to a 30% NaCl brine environment. The hydraulic conductivity of brine was found to be greater than that of water in soils where the dominant clay mineral was montmorillonite, whereas a soil rich in illite and kaolinite was virtually insensitive to variations in solution composition. Increases in brine hydraulic conductivities were most pronounced in soils high in montmorillonite where sodium was the dominant adsorbed ion. They demonstrated the most labile hydraulic conductivities. Fine-grained soils, high in montmorillonite clay content, were prone to alteration in engineering properties when soaked in a 30% NaCl brine. However, brine soaking had little effect on soils rich in illite–kaolinite.
Mixing zone studies in the Grand River Basin
Authors: Gowda T. P. Halappa , Post L. E.
Published: January 2010

A steady state mathematical model based on the "stream tube" concept was utilized to evaluate the impact of various viable management options on the mixing zone boundaries for nonionized ammonia and total residual chlorine at the Grand River below Waterloo, Kitchener, and Galt, and the Speed River below Guelph. The options evaluated as part of the Grand River Basin Water Management Study include various river flows and effluent flows projected for the planning period 1981–2031. The predictions indicate that a zone of passage equal to 60% of river flow is attainable for chlorine in all cases except in the Speed River below Guelph beyond the year 2001, and in-plant nitrification is required at Waterloo and Kitchener under the present conditions in order to comply with the objective for nonionized ammonia. At Guelph, with in-plant nitrification, the model predicts that the ammonia objective will not be met for existing and future summer conditions and for winter conditions beyond the year 2001. For Galt, the ammonia objective is met with conventional secondary treatment under all options. The maximum longitudinal boundary of limited use zone for various options is also summarized. Key words: ammonia, chlorine, limited use zone, management options, mixing zone, modelling, rivers, zone of passage.
A stochastic description of temporal daily rainfall patterns
Authors: Nguyen Van-Thanh-Van
Published: January 2010

A stochastic approach to characterization of temporal rainfall patterns is proposed wherein a rainfall event is defined as an unbroken sequence of consecutive daily rainfalls. A stochastic model is developed to determine the probability distribution of cumulative rainfall amounts at the end of each day within a total rainfall event duration of n days. The model is structured such that the distribution of daily rainfall depths can be approximated by an exponential distribution and the rainfall occurrence process can be described by a first-order stationary Markov chain. An illustrative example was presented, using a 32-year daily rainfall record at Dorval Airport on Montreal Island. The results of this example have demonstrated the adequacy and descriptive capabilities of the model. It can be concluded that the methodology proposed here seems to be more general and more flexible than those that have been used in previous investigations. Key words: daily rainfall process, temporal rainfall pattern, stochastic model, stochastic hydrology, exponential distribution, Markov chain.
Ontario's heritage bridge program
Authors: Cuming David J.
Published: January 2010

Conservation of the built environment is becoming a major aspect of planning activity in the 1980s. Current economic conditions have necessitated rehabilitation and renovation of many buildings and structures rather than their replacement. In response to these conditions the Ontario Ministries of Transportation and Communications and of Citizenship and Culture have initiated the Heritage Bridge Program. A key component is the establishment of a list of heritage road bridges. There is a presumption that listed bridges should be conserved where feasible. Criteria are utilized to evaluate bridges for prospective nomination to the list. Conservation strategies are recommended for protecting those bridges listed. Complementary funding provisions have been agreed to by the Ministries to encourage listed bridge conservation. The program, the first of its kind in Canada, is a systematic and comprehensive way of protecting a unique aspect of Ontario's engineering heritage. Key words: historic bridges, engineering heritage, conservation, rehabilitation, evaluation criteria, Ontario government program.
Analysis of three-dimensional frames with flexible beam–column connections
Authors: Ang K. M. , Morris G. A.
Published: January 2010

A procedure is presented for analyzing three-dimensional rectangular steel frames that incorporate any of five commonly used beam–column connection types. A method is described for expressing the moment–rotation behavior of all connections of a given type (for example all end plate connections) in terms of a single standardized Ramberg–Osgood function.The method involves an examination of experimental information on the moment–rotation behavior of a given connection type to determine the influence of various size parameters, such as end plate thickness. It has been used to generate standardized moment–rotation functions for five common connection types and the functions are presented.An iterative, successive approximation structural analysis procedure is described in which repeated approximations are made to assumed stiffness characteristics of all connections in the structure. When the appropriate connection stiffnesses have been determined, a single linear analysis is performed to determine the correct structural displacements and internal forces. Thus, the nonlinear behavior of the connections is properly accounted for. Examples are presented to demonstrate the influence of connection deformation on structural displacements and internal forces.
Récupération de microalgues en eaux usées : étude comparative de divers agents floculants
Authors: Lavoie A. , Noüe J. de la , Sérodes J. B.
Published: January 2010

Flocculation appears to be the best technique for harvesting microalgae produced during a biological tertiary treatment of domestic wastewaters. Inorganic salts (Al2(SO4)3, KAl(SO4)2, Ca(OH)2) and chitosan have been compared in this respect. Chitosan appears to be the most satisfactory with reference to effectiveness and economy since recovery of 95% of the algae is possible with a dose of 30 mg L−1 at a pH of 7.0. The physiological condition of the algae influences their ability to flocculate, which is optimum from the end of the exponential growth phase to the plateau phase. Key words: flocculation, chitosan, alum, microalgae, wastewaters, tertiary treatment.
The measurement of concrete permeability
Authors: Hope Brian B. , Malhotra V. Mohan
Published: January 2010

This paper describes the construction and operation of an apparatus for the measurement of concrete permeability. The concrete samples used in the apparatus are cast in epoxy resin before insertion in a pressure cell. Uniaxial water flow, under pressures up to 3.5 MPa, is ensured by O-ring seals.Results are presented for the permeability of laboratory samples with water/cement ratios varying from 0.35 to 0.75. Key words: concrete, permeability, apparatus.
Modelling criteria for bubble plumes—a theoretical approach
Authors: Tsang Gee
Published: January 2010

A theoretical investigation is made to derive the parameters that govern the dynamic similarity between prototype and model bubble plumes. It is shown in the study that, for a complete similarity between the prototype and the model, the buoyancy flux from the source, the size of the bubbles, and the expansion of the gas bubbles all have to be simulated. This is translated into the observation of the Froude law, the Weber law, and the expansion law in the model study. The expansion law requires that, for a reduced model, the study be conducted under partial vacuum and, for an enlarged model, the study be conducted under pressure.The physical properties of common fluids impose severe constraints on the model study. If the Weber law is to be satisfied, the smallest model permissible will only be half the prototype size. To conduct experiments under partial vacuum, the boiling of the model liquid has to be contended with. For practical reasons, a certain degree of violation of the similarity laws seems to be unavoidable. The theoretical investigation calls for systematic experiments to examine the quantitative effect of the different similarity parameters and the degree of violation of the similarity laws permissible in solving practical problems. Key words: plume, bubble, model, simulation, criteria, theoretical.
Hydrodynamic of circular primary clarifiers
Authors: Abdel-Gawad Sameh M. , McCorquodale John A.
Published: January 2010

The strip integral method has been applied to a typical restricted inlet circular primary clarifier, in order to simulate the flow pattern and dispersion characteristics of the flow. This method assumes a dominant flow direction and with the use of velocity shape functions reduces the equations of motion and continuity to a set of simultaneous ordinary equations. Three shapes were chosen, corresponding to the boundary layer, the potential core, and the free mixing and recirculation zone. A Runge–Kutta method was used to integrate the set of ordinary differential equations. A standard finite element method was used in the withdrawal zone. The numerical predictions compared favorably with experimental velocity distributions obtained in a physical model of circular sedimentation tanks. The model is restricted to circular primary clarifiers of discrete suspension with low concentration operating at neutral density environment.The model was used to predict the velocity and dispersion characteristics of the circular tanks used at the West Windsor Pollution Control Plant, Windsor, Ontario.
Uncertainty, time, and risk in the optimization of maintenance and rehabilitation of pavements
Authors: Bein Peter
Published: January 2010

A Markov decision model for the optimization of one section of highway or street pavement maintenance and rehabilitation incorporating utility theory is outlined. The model takes account of the uncertain pavement behaviour and of the interdependence of maintenance actions over time. An approach for estimating and updating Markov transition matrices for pavements is proposed.The objective function quantifies the pavement manager's attitudes toward the risk posed by the probabilities of pavement condition, magnitudes of consequences, and timing of decisions. Multiattribute utility theory is employed to aggregate multiple criteria, and to model the pavement manager's preferences in multiyear planning scenarios.The methodology is applied to the optimization of maintenance and rehabilitation of one highway pavement section. The preferences of five engineers are tested. These tests show that additive evaluation models are not appropriate for pavement management. Utility functions of one engineer are used in an illustrative example to demonstrate feasibility of the approach.The presented model deals with the project level of decisions. However, the Markov decision approach combined with multiattribute utility can also be useful when modified to deal with questions arising at the network level. At both levels, the approach provides a powerful research tool capable of answering a variety of pavement management questions. Key words: pavements, maintenance and rehabilitation, management aids, Markov decision model, multiattribute utility, probability updating.
Resistance factors for steel highway bridges
Authors: Kennedy D. J. Laurie , Baker Karen A.
Published: January 2010

Resistance (performance) factors for bridge members composed of rolled and welded steel sections are developed consistent with the live and dead load factors given in the Ontario Highway Bridge Design Code (OHBDC).Ratios of the load components of seven different spans of plate and box girder bridges are used with the statistical data for loads used in the development of the OHBDC. Monte Carlo simulation techniques are used to compose distribution curves for the various resistance functions from distribution curves describing the appropriate geometric properties, material properties, and test/predicted ratios. Using the 0.001 and 0.05 fractiles of the distribution curves so obtained for the resistances, mean values and coefficients of variation are obtained for equivalent lognormal distribution curves.Resistance factors are then developed for the fully plastic moment resistance, the yield moment, the inelastic buckling moment resistance, the elastic buckling moment resistance, the moment resistance of composite sections, and column resistances for slenderness parameter values of 0.8, 1.0, and 1.2. A general resistance factor of 0.93 is recommended for all the resistances and bridges studied. Resistance factors of 0.95 and 0.98 are considered appropriate for the flexural resistance of bridges composed of welded and rolled sections, respectively. Key words: bridges, limit states, Monte Carlo simulation, performance factors, resistance factors, steel, rolled sections, welded sections.
Floor trusses subjected to a concentrated load
Authors: Temple Murray C. , Racic Dan , Pavlica Sandy
Published: January 2010

The results of extensive testing of floor joists subjected to a concentrated load are presented. These floor joists are constructed with 2 × 4 (38 × 89 mm) flanges and steel V web members. The load-carrying capacity of these joists when subjected to a uniformly distributed load has been investigated previously. These joists, however, are often subjected to a concentrated load as the result of a floor opening, and this is the subject of this investigation. The use of this floor truss is similar to two 2 × 12 (38 × 286 mm) joists arranged back-to-back.The floor trusses were modified by adding extra material to the joists and by nailing the exposed bottom flange grips of the V web members. Adding the extra material resulted in the formation of a box section over part of the span. Another method, adding a solid piece of lumber inside the truss to form an I section, was also tried. A concentrated load was applied to the reinforced truss and the truss was loaded to failure. A significant improvement in load-carrying capacity was achieved through a simple modification to an ordinary floor truss.
A graphical technique for free-surface transients
Authors: Curtis C. R. , Wilson K. C.
Published: January 2010

The method of characteristics is applied to free-surface transients using graphical constructions. It is shown that by use of an appropriate stage variable the hodograph plane can be constructed for any desired prismatic geometry, and the commonly encountered case of the circular section is investigated in detail. Friction effects are lumped at "chokes" in a fashion directly analogous to that used for water hammer analysis. A method is demonstrated for estimating the diminution of maximum stage as a flood peak moves down a storm sewer or other conduit, and it is verified that the results compare with experimental data with no more discrepancy than is obtained with detailed computer programs. This graphically oriented representation of free-surface transients complements computer techniques and can be particularly useful in the cut-and-dry of the preliminary design process. Key words: fluid transients, sewers (storm), channels (waterways), hodograph plane.
Uncertainty analysis of a delineated floodplain
Authors: McBean Edward , Penel Jacques , Siu Kwok-Lui
Published: January 2010

The delineation of floodplains involves, in most circumstances, solving the one-dimensional energy equation. However, uncertainties in the identified floodplain arise from both computational and data uncertainties; data uncertainties are concluded to be generally more significant than computational uncertainties.A method is developed to calculate the uncertainty in floodplain delineation arising from data uncertainties. The proposed method requires only HEC-2 computer output and a small computer program. Application of the method to two case studies and comparison with another uncertainty method suggest that the proposed uncertainty theory is applicable to practical situations within the given constraints. Key words: data uncertainty, floodplain, uncertainty analysis, water profile computation.
Analysis of breakup and ice jams on the Athabasca River at Fort McMurray, Alberta
Authors: Andres D. D. , Doyle P. F.
Published: January 2010

During breakup, severe ice jams form at Fort McMurray, Alberta because of the dramatic change in the character of the Athabasca River at that location. Such jams, which produce water levels in the order of 10 m above the normal open water stage, were documented in 1977, 1978, and 1979. Additional channel surveys and improved estimates of discharge made since the initial analysis have redefined the ice jam characteristics. The Manning roughness coefficient of the underside of the ice jams was found to be 0.072. The new discharge estimates, which were up to twice those previously reported, result in a calculated coefficient of internal friction of 0.8–2.7. This is 30–100% greater than previous estimates, but still similar to values determined for ice jams at other locations.Even with the variation in the coefficient of internal friction, the river stage due to an ice jam at Fort McMurray could be computed with reasonable accuracy for a range of given discharges. If jams form downstream of the mouth of the Clearwater River at discharges greater than 800 m3/s (considerably less than the 1-in-2-year open water flood), flooding will occur within lower Fort McMurray. Unfortunately, the frequency of such an event is unknown because the probabilities of both the discharge being exceeded and the jam occurrence cannot be defined. Key words: ice, breakup, ice jam, ice roughness, flooding, hydraulics.