bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of a chelating agent (DTPA) on anaerobic wastewater treatment in an upflow sludge blanket filter
Authors: Kennedy K. J. , Andras E. , Elliott C. M. , Methven B.
Published: January 2010

This paper describes the effect of the cationic chelating agent penta sodium dithylene triamine penta acetate (DTPA) on anaerobic granular biomass. Batch and continuous tests indicated that acidogenic and methanogenic activity were relatively unaffected by short-term exposure to DTPA. However, long-term exposure to high concentrations (> 1800 mg/L) and low concentrations (180 mg/L) in the absence of a sacrificial trivalent cation eventually led to inhibition of hydrogen consuming and acetoclastic methanogens. An anaerobic sludge bed reactor exposed to DTPA which had been complexed to sacrificial Fe3+ was not inhibited. Key words: anaerobic, wastewater, pulp, paper, DTPA, penta sodium diethylene triamine penta acetate, cationic chelator.
Hydraulics of culvert fishways IV: spoiler baffle culvert fishways
Authors: Rajaratnam N. , Katopodis C. , Lodewyk S.
Published: January 2010

This paper presents the results of an experimental study on the hydraulics of culvert fishways with spoiler baffles. Four designs were studied with the heights of the baffles equal to 0.09D and 0.15D and longitudinal spacings of 0.53D and 1.06D, where D is the diameter of the culvert. Design equations have been developed relating the flow depth to the flow rate, the diameter and the slope of the culvert for each baffle design. Expressions have also been found for the barrier velocity. Key words: culverts, fishways, hydraulics, turbulent flow, open-channel flow.
Waste disposal facilities and community response: tracing pathways from facility impacts to community attitude
Authors: Zeiss Chris , Atwater James
Published: January 2010

Host communities often very strongly oppose municipal waste disposal facilities despite the absence of very serious physical impacts. In order to effectively manage facility impacts and siting process to reduce host community opposition, waste management engineers and planners must understand the linkage between physical impacts and beliefs and the resulting attitudes in the host community. Physical impacts, community beliefs, and attitudes were assessed at two typical waste facilities, a landfill and an incinerator for municipal solid waste. Typical landfill impacts consist of water and air quality effects, odors, noise, and visual impacts; incinerators generate air quality impacts, visual and slight noise effects. While residents' general beliefs about facility impacts focus on obvious physical impacts (noise, odor, air emissions), residents' opinions of specific waste facilities comprise a broader set of physical and nonphysical impacts, including property value losses, community image impact, and loss of community control. These underlying, nonphysical impact beliefs are associated with exposure to obvious nuisance impacts and correlate strongly with residents' attitudes about the facility. Therefore, impact management efforts will be most effective if they, first, correctly identify underlying concerns and, then, manage the physical impacts that trigger them. Key words: waste disposal facilities, physical impacts, community beliefs, attitude, impact management, community acceptance.
Moment redistribution in structural concrete codes
Authors: Cohn M. Z. , Lounis Z.
Published: January 2010

Features of current moment redistribution provisions in American and European structural concrete standards are reviewed and compared. Some major differences are identified, along with their common objective of ensuring the rotation compatibility at the ultimate limit state of continuous structures. High amounts of moment redistribution (and the related economic advantages) sometimes tend to go against satisfactory service behaviour, particularly for prestressed members. Examination of moment redistribution formulae and main serviceability criteria suggests that some major variables currently neglected play a considerable role in ensuring the largest moment redistribution together with satisfactory service behaviour. Among these variables the dead to live load ratio, the degree of prestressing, the specified partial load factors, and the allowable performance target values (cracks, deflections, stresses) are investigated. Appropriate formulae to allow for their contribution are proposed, which may be easily implemented in any code. Finally, two numerical examples illustrate the practical implications of the theoretical aspects investigated in the paper. Key words: moment redistribution, reinforced and prestressed concrete, serviceability control, structural codes.
Analysis of laterally loaded flat-plate structures
Authors: Morris Glenn , Omar Husam
Published: January 2010

Flat-plate reinforced concrete structures tend to behave nonlinearly, even at service load levels, when subjected to lateral loading. This is due mainly to the deformations that occur at the column-to-plate boundaries. Currently available structural analysis computer programs assume linearly elastic behaviour and thus underestimate lateral displacements. This paper describes an efficient, easy-to-use structural analysis procedure and computer program for predicting the nonlinear response of flat-plate structures subjected to lateral loading. The structure is assumed to be a three-dimensional frame comprised of linearly elastic columns, flat-plate floor panels and shear walls, and nonlinear "connections" between the columns and the flat-plate floors. Utilizing all available experimental data, standardized functions have been derived to predict the nonlinear moment–rotation behaviour of these plate-to-column connections. The functions have been incorporated into the structural analysis computer program. Examples are presented to illustrate the capabilities of the program, to compare results computed by it with published results, and to illustrate the effects of several geometric and material parameters on the behaviour of the structure. Key words: reinforced concrete, flat plate, structural analysis, nonlinear analysis, lateral load analysis.
Starred angles supporting secondary trusses
Authors: Temple Murray C. , Mok Kenneth Hon-Wa
Published: January 2010

In some large industrial buildings, it is common to span large areas by using primary trusses in one direction and secondary trusses in the other. The secondary trusses frame into the vertical web members in the primary trusses. Starred angles are frequently used as the vertical web members in the primary trusses because of their symmetrical cross section and the ease with which the connections can be made. These starred angles are usually designed as axially loaded members, but the open nature of the cross section and the fact that the secondary truss frames into one of the angles has raised some doubts about this loading assumption. As a result of this concern, an experimental research program was undertaken to investigate the behaviour and strength of starred angle web members supporting secondary trusses. The results obtained indicate that these starred angle compression members are not concentrically loaded, as the stress distribution across the angles is not uniform. It was found that if the slenderness ratio is modified in accordance with the requirements of ASCE Manual 52, the load-carrying capacity of the starred angles supporting secondary trusses can be determined using Clause 13.3.1 of CAN3-S16.1-M84. Key words: angles (starred), buckling, columns (structural), connections, trusses.
Implications of the 1988 Saguenay earthquake on Canadian seismic strength specification
Authors: Tso W. K. , Zhu T. J.
Published: January 2010

The November 25, 1988, Saguenay earthquake was the most significant seismic event in eastern North America over the last 50 years. Based on strong ground motion records from this earthquake, an analytical study was undertaken to evaluate the seismic design base shear provisions of the National Building Code of Canada for buildings located in the eastern regions of Canada. In light of the observed damage to masonry structures in the epicentral region, emphasis was placed on the evaluation of the codified minimum seismic strength for masonry structural systems. Key words: earthquake, ground motion, seismic design strength, code, masonry, buildings, damage, ductility.
Seismic analysis of links of various lengths in eccentrically braced frames
Authors: Ghobarah A. , Ramadan T.
Published: January 2010

Eccentrically braced steel frames have excellent elastic stiffness under moderate lateral loads and good ductility when subjected to severe seismic loading conditions. Under extreme loading, the inelastic behaviour is designed to be confined to a ductile link element. The behaviour of links of various lengths in eccentrically braced frames is evaluated using a finite element model. The link is subjected to extreme cyclic loading simulating a severe earthquake. The effect of the link length on its performance, capacity for energy dissipation, plastic mechanisms, and mode of failure are investigated. Measures for improving the performance of long links are examined. It was found that the most efficient link is the short shear link. However, the short link deformation is characterized by large angles of deformation, which may cause substantial damage to the nonstructural elements. On the other hand, long links were found to have smaller angles of deformation than short links, but with reduced ductility levels. An effective approach to improve the performance of long links is by increasing the flange thickness of the link section with the appropriate adjustment to the stiffener design. This technique can be applied to links of length up to 1.4 times the critical shear link length. Key words: steel, eccentric, braced, frame, link, seismic, ductility, design.
Correction coefficients for uniform channel flow
Authors: Li Damei , Hager Willi H.
Published: January 2010

The kinetic energy and momentum correction coefficients are considered. After a review of pertinent literature, the discussion is restricted to uniform open channel flow. It is found both theoretically and experimentally that the coefficients depend significantly on the Manning roughness coefficient, and that the kinetic energy correction coefficient may directly be related to the momentum correction coefficient. Further, the effect of local variation of correction coefficients is much smaller than the variation of dynamic pressure times the correction coefficient. Therefore, the concept of constant coefficient as proposed earlier is justified. Key words: backwater curve, channel, distribution, flow, river.
Brittle to ductile transition during indentation of ice
Authors: Gold L. W.
Published: January 2010

The brittle to ductile transition in the deformation behaviour of ice is considered for indentation by a flat, rigid indentor under fully elastic plane strain or plane stress conditions. It is assumed that failure occurs when a crack initiated near an edge of the indentor is propagated immediately by the maximum shear stress at the site. Consideration is given to the relaxation of the elastic moduli and the change in the critical stress intensity factor for crack propagation that occur in the transition range of strain rates. The analysis shows that for the assumed conditions, the indentation pressure varies inversely with the square root of the width of the indentor, and increases to a maximum with decreasing strain rate. It also indicates that the necessary and sufficient conditions for brittle failure of ice are a critical combination of shear strain and strain rate that will cause a crack to form, which propagates immediately under the imposed stress. Key words: ice, elasticity, indentation, brittle to ductile transition, fracture mechanics, failure.
Évaluation du potentiel de réactivité alcaline des granulats à béton produits dans les Basses-Terres du Saint-Laurent du Québec (Canada)
Authors: Fournier B. , Bérubé Marc-André
Published: January 2010

Seventy-one samples of aggregates representative of the various sedimentary rock types exploited in the St. Lawrence Lowlands were submitted to standard and experimental laboratory tests to evaluate their potential alkali-reactivity in concrete. Among these, only the Trenton and Black River limestones with more than 6% insoluble residues produced excessive expansion in the concrete prism test, the most reliable method in assessing the alkali-reactivity potential of concrete aggregates. Expansion values of 0.1 and 0.15%, obtained respectively after 14 days in the accelerated mortar bar test (1 M NaOH at 80 °C) and 5 h of autoclave curing (0.17 MPa at 130 °C and 100% relative humidity), can only be used as acceptance limits, since nonexpansive aggregates (as per the concrete prism test) from the Black River, Chazy and Beekmantown Groups induced excessive expansion in these tests. Limiting the reactive alkali content of the concrete mix to 3 kg/m3 or using cements containing between 5 and 10% of condensed silica fume can reduce the risks of deleterious reactions associated with the siliceous limestone aggregates produced in the St. Lawrence Lowlands. Key words: concrete, aggregates, alkali–aggregate reaction, accelerated test methods, preventive measures, condensed silica fume.
Load sharing factors in timber bridge design
Authors: Bakht Baidar , Jaeger Leslie G.
Published: January 2010

It is well recognized that the structural capabilities of timber that are relevant to structural design vary not only because of natural variations in the material properties of the timber but also, randomly, as a consequence of several aspects of the structure itself and the loading. These factors are accounted for in the design process through the modification factors applied to the calculated resistance of the various components. One of these factors is the load sharing factor, which is intended to account for the enhanced strength of an assembly of components which results from the reduced probability of simultaneous occurrence of low strength in more than one component of the grouping. All the modification factors, including the load sharing factor, are usually derived by ignoring the fact that the two sides of the design equation, representing load effects and resistances respectively, may be interrelated. Despite its significance, the load sharing factor has been specified in design codes as a result of only cursory investigations, which have not rigorously considered the mechanics of behaviour of the assembly of timber components. The results of an analytical study are presented in this paper; the load sharing factor is developed by considering the interaction between the two sides of the design equation and also by explicitly taking account of the mechanics of behaviour of groups of timber components. It is shown that the load sharing factor can be conservatively presented as a relatively simple function of the number of timber components that can be assumed to be subjected to the same deformation as one another. Key words: factored resistance, design equation, load sharing, modification factor, modulus of rupture, strength variability, timber bridges.
Reduction of cavitation on spillways by induced air entrainment
Authors: Kells James A. , Smith C. D.
Published: January 2010

Spillways for medium and high head dams may be exposed to high velocity flows and the associated destructive phenomenon of cavitation. Cavitation may occur at rough spots in the surface of the chute or tunnel, at local discontinuities in the finished surface such as construction joints, and at locations along critical flow profiles having significant deviations from design specifications. This paper addresses, on the basis of a review of the literature, a method for preventing or reducing cavitation damage on spillways through the use of spillway aerators. While the ability of induced or forced aeration to reduce or eliminate cavitation has been known for many years, it is only in relatively recent times that the aeration mechanism has been used to this advantage on spillways subject to high velocity flow. The recent application of aerators to spillway design is related, in part, to the trend toward higher head dams and larger design unit discharge rates. Design considerations and criteria for spillway aerators are presented in the paper, and the use of physical hydraulic models to make determinations of aerator performance is discussed. The intent of the paper is to provide a document with sufficient detail and scope to be useful as a first resource for spillway design practitioners. Key words: aerator design, air entrainment, cavitation, design criteria, high dam, model – prototype comparison, physical hydraulic model, spillway, spillway aeration.
Uplift resistance of interior footings of low-rise buildings
Authors: Temple Murray C. , Loong Chun-Wah Bernard , Monforton Gerard R.
Published: January 2010

An experimental and analytical study was conducted to assess the contribution of the slab to the uplift resistance of interior footings in low-rise buildings. The experimental program involved applying uplift loads to seven laboratory models, each consisting of a column and footing, slab, and backfill material. The analytical study consisted of a linear finite element discretization in which the slab was modeled using plate bending elements. The backfill material was approximated by linear compression springs with spring constants directly related to the experimentally determined modulus of subgrade reaction. It is concluded that the current design practice of ignoring the strength of the slab in calculating the uplift resistance of footings is very conservative. Based on the experimental results, an empirical equation is suggested for determining the uplift capacity of the slab. Key words: footings, low-rise buildings, uplift resistance, wind forces.
Marine outfalls for small coastal communities in Atlantic Canada
Authors: Sharp J. J.
Published: January 2010

Atlantic Canada is a relatively sparsely populated region with a few large urban centres and many small communities. Many of these communities rely on secondary treatment plants for treatment and disposal of domestic wastes. However, with a generally low tax base and a small pool of technically qualified personnel, maintenance on the plants is often of low quality so that their performance deteriorates after a few years of operation. In this paper the argument is advanced that ocean outfalls provide a more satisfactory means of treating and disposing of domestic wastes in such cases. Details are provided to confirm the low level to which some plants perform; and the design, installation, and postconstruction monitoring of a small ocean outfall are described to show the advantages of this alternative. Key words: ocean outfalls, marine treatment, waste disposal, pollution, environment.
Optimization of short-term operation of a single multipurpose reservoir — a goal programming approach
Authors: Reznicek Karolj K. , Simonovic Slobodan P. , Bector C. R.
Published: January 2010

The complex real-time reservoir operation model consists of flow forecasting, reservoir operations planning, and multiobjective modules. In the present paper the original reservoir operations planning module based on a linear programming (LP) formulation is substituted with a goal programming (GP) formulation. The advantage of applying goal programming instead of linear programming lies in the smaller input data requirement, and simpler model formulation. The LP approach requires two-dimensional information while the GP approach needs only one-dimensional information. The impact of change of the operations planning routine on the results of the complex model is observed and commented on a case study. The application of GP instead of LP is found viable, in certain cases even advantageous, giving a better overall objective function value. Key words: reservoir operation, optimization.
Economic risk analysis of large engineering projects
Authors: Ranasinghe Malik , Russell Alan D.
Published: January 2010

A consistent, four-moment-based approach for quantifying time and economic risks is presented. The goal is to produce a computationally economical approach that can be used to explore the time and economic feasibility of various strategies for executing and sequencing major work packages that describe an engineering project. A three-level hierarchy of variables is used, starting with time, cost and revenue performance at the work package/revenue stream level to net present value and internal rate of return at the project decision level. The treatment of correlations between primary variables at all levels of the hierarchy is included. A modified form of the probabilistic network evaluation technique (PNET) algorithm is presented for quantifying time uncertainty. Use of limiting values (0, 1) of the PNET transitional correlation provides bounds for all decision variables. A comparison with Monte Carlo simulation of a case study is presented to demonstrate the validity and the computational economy of the analytical approach. Key words: economic risk quantification, large engineering projects, probability analysis, moment analysis, Monte Carlo simulation.
Treatment of slaughterhouse effluent using an anaerobic filter
Authors: Harrison J. T. , Viraraghavan T. , Sommerstad H.
Published: January 2010

A pilot-scale study was conducted to evaluate the treatment performance of an upflow anaerobic filter (AF) on a slaughterhouse effluent. The effluent flow rate through the AF was changed for seven treatment trials, and performance was evaluated by the amount of COD removed. The COD removals ranged between 37% and 77% and were related to the reciprocal of the hydraulic retention time, in accordance with the Young and McCarty empirical model. The COD removals in this study were less in comparison to other similar AF studies, and factors attributed to this included low solids retention time and reactor design. The average removals of total coliforms, fecal coliforms, fecal streptococci, and standard plate count densities through the AF were 29%, 18%, 95%, and 65% respectively. The average methane content of the biogas was 71%. The methane yields ranged between 0.19 and 0.23 (m3 STP/kg COD removed). Tracer results showed that effluent flow through the AF was predominately completely mixed. Key words: anaerobic filter, slaughterhouse effluent, media, indicator microorganisms, treatment, methane.
Management of risk in the public interest
Authors: Lind N. C. , Nathwani J. S. , Siddall E.
Published: January 2010

There is no Canadian policy for the management of health and safety in the public interest. Both lives and resources are lost as a result. Limited life-saving resources ought to be spent efficiently in the public interest. If the life expectancy at birth is the measure of safety overall, then account must be given of the efficiency of any safety program, policy, project, or regulation in terms of the years of life in good health saved and the cost incurred. A comparison is made of 26 programs implemented in the United States, and it is shown that they collectively waste several thousand lives per year; 95 cents on the dollar is wasted. An absolute upper cost limit is established, which no life-saving program can exceed without consuming more human time than it returns. Some elements of a rational safety policy, and some concrete steps that ought to be taken now towards its implementation, are suggested. Key words: risk, management, public interest, health, safety, life, human development, index, efficiency, ethics, profession, accountability.
Applications of expert system building tools in structural design
Authors: Sakr K. M. , Hosain M. U.
Published: January 2010

This paper summarizes the basic concepts of expert systems and describes some of the applications of three commercially available expert system tools. The function of the various components of the tools is explained using simple design examples. It is concluded that a tool can be employed to develop useful expert systems for real-world applications, provided factual and heuristic material is available for creating a knowledge base. Key words: artificial intelligence, knowledge-based expert systems, knowledge base, inference mechanism, expert system building tools, structural design, applications of expert system building tools.
Effects of mixing on anaerobic treatment of potato-processing wastewater
Authors: Lin K. C. , Pearce M. E. J.
Published: January 2010

Four laboratory-scale reactors were used to study the effects of mixing intensity and mixing duration on the anaerobic treatment of potato-processing wastewater at 20 °C. The mixing intensities were set at impeller speeds of 0, 20, 50, and 100 rpm. Two mixing durations were studied: 45 and 15 min/h. It was found that both mixing intensities and mixing durations studied and their joint effect significantly affected the steady-state performance of the anaerobic reactors in treating the potato-processing wastewater with respect to organics and solids removals and methane production. Key words: mixing effects, anaerobic treatment, potato-processing wastewater, organics and solids removal, methane production.
Survey of household hazardous waste generation and collection preferences in the City of Vancouver
Authors: Jones E. L. , Atwater J. W.
Published: January 2010

A survey of over 200 households in Vancouver was conducted to determine stored quantities and generation characteristics of household hazardous wastes (HHW). Respondents were also asked to identify their preferences and concerns regarding the design of a collection program for these wastes. The results were used to estimate the quantities of HHW disposed of annually, and the quantities and profiles of wastes that could be received at a typical depot collection program in the City. Different operating parameters for both depot collection programs and household collection programs were compared and evaluated for effectiveness. Public willingness to participate in different collection programs was evaluated, and the collection needs of different residential areas were assessed. Several differences in waste generation and public willingness to participate were noted between areas of apartment dwellers and detached residence dwellers, and of high and low income levels. Recommendations were made to assist in the design of an effective HHW collection program for the City of Vancouver. Alternatives for the design of a collection program were developed. Key words: household hazardous waste, solid waste, household waste, hazardous waste, waste collection, small quantity generator, waste generation, special waste.
Test results on the effects of weathering on plastic coverings
Authors: Glockner P. G.
Published: January 2010

Results from ongoing tests at The University of Calgary on the degradation due to weathering of transmissivity properties of a few commonly available PVC translucent sheets, including two kinds of Herculite, Fabrenes, ECS, and Vintex, are summarized. Samples of these materials were exposed to the elements in Calgary for a period of up to 47 months; the reduction in their transmissivity, in comparison with data from unweathered samples and over the range of the electromagnetic spectrum of interest in horticulture, was determined. Key words: plastic sheets, roofing, translucent, transmissivity degradation, weathering.
Multivariate analysis of the water quality of a set of Quebec lakes: finding watershed explicative factors of the acidification process
Authors: Lachance M. , Bobée B. , Marsily G. de
Published: January 2010

In this study, a new methodological approach is proposed to analyze the spatial variability of the water quality of a set of lakes. The Quebec region under study is located in the southeast part of the Canadian Shield between the Ottawa River and the Saguenay River. The proposed methodology is based on the combined use of correspondence analysis and hierarchical classification analysis. These methods provided the analyst with a geometric representation of the spatial variation of the physicochemical parameters of the water quality (pH, alkalinity, calcium + magnesium, sulfate) recognized as indicators of the acidification of aquatic ecosystems. Afterwards by imposing a contiguity constraint in hierarchical classification, the analysis led to the delimitation of five geographical regions that are similar with respect to the four variables related to the acidification process. Then the relations between the water quality variables and some biophysical variables are examined. The multiple correspondence analysis made it easier to identify the biophysical variables of the watershed that are explicative of the water quality variables. Amongst these explicative variables examined, we have identified that the sulfate concentration in the precipitation, the annual precipitation, the altitude of lakes, and the type of vegetation and geology are more or less explicative for the alkalinity, the pH, the Ca + Mg, and the sulfate. The results can be used to build a regression model for the prediction of some physicochemical variables from the knowledge of certain key variables describing the biophysical characteristics of the watersheds. Key words: spatial variability, multivariate analysis, acidification, water quality, explicative factors, lakes, Quebec.
Treatment of a wood products Superfund wastewater: a case study
Authors: Dahab M. F. , Becker H. L. , Riley T. E.
Published: January 2010

This paper reports the results of studies designed to determine the treatability of wastewater from a wood products Superfund site using conventional technologies. The treatability studies consisted of a series of filtration pretreatment experiments using different types of filter media to remove suspended solids and emulsified floating oils and grease prior to batch and continuous activated carbon adsorption experiments to remove semi-volatile organics from the wastewater. The results indicated that adequate suspended and emulsified solids removal efficiencies were obtained prior to carbon adsorption. Continuous activated carbon experiments resulted in excellent removal of the most prevalent organics of interest. The results of the experiments were instrumental in establishing baseline design data for full-scale implementation of a remediation system. Key words: hazardous waste, Superfund, wood products, wastewater, pentachlorophenol, adsorption.
Determining the elevation, slope, and waviness of surfaces using the procedures of CAN/CSA-A23.1-M90 Appendix E
Authors: Loov Robert E. , Rodway Lloyd E.
Published: January 2010

The 1990 edition of the Canadian Standards Association (CSA) Standard CAN/CSA-A23.1 “Concrete materials and methods of concrete construction” bases the standard for the evaluation of the surface profile of concrete surfaces either on measurements using a 3 m straightedge or on the so-called F-number system. The standard recognizes, however, that both of these procedures use only a portion of the survey information and “filter out” information related to other wavelengths. To provide a more comprehensive treatment, which utilizes more fully the survey data, an alternative procedure has been provided in Appendix E of the CSA standard. This paper provides a summary of the required equations and a detailed example shows the results obtained from a survey of an actual surface. Key words: concrete, concrete slabs, floors, measurement, surfaces, surveying, tolerances, waviness.
An innovative detail for precast concrete beam–column moment connections
Authors: El-Ghazaly Hany Ahmed , Al-Zamel Heyad Saud
Published: January 2010

A new detail is introduced for precast concrete beam-to-column moment connections. The detail consists of a connecting steel frame used to mechanically connect the threaded end protruding reinforcing bars from beam and column. The connection detail is made convenient to assemble where the erection method resembles that of steel construction. No idle crane time is necessary, since the connecting steel frame is designed to carry the beam's own weight. When the connection construction is completed, the joint functions as a moment resisting hard connection. The experimental testing program involved testing of twelve full-scale specimens in addition to a pilot test. Of the twelve tests seven are flexural tests, three are shear tests, and two are monolithic flexural tests for comparison. Modes of failure in the flexural tests were mainly due to rupture of tension reinforcement; however, premature slippage of the rebars may occur under certain conditions, but could be conveniently prevented. In the shear tests, diagonal tension crack failure predominated. If the connection parameters are properly selected, the connection will be capable of developing the beam's full plastic moment and undergo sufficient rotation before collapse. Key words: precast concrete, moment connections, connecting steel frame, stiffness, strength, ductility.
Static and dynamic tests of timber shear walls fastened with nails and wood adhesive
Authors: Filiatrault A. , Foschi R. O.
Published: January 2010

This paper presents an experimental investigation into the seismic behaviour of timber shear walls fastened with nails alone or with nails in combination with wood adhesive. The responses of both types of shear walls were determined under slow, quasi-static racking loads and also under dynamic, earthquake-induced conditions. The experimental results showed that the introduction of the adhesive makes shear walls much stronger but also more brittle than conventional nailed walls. It was observed that shear walls incorporating nails and adhesive behaved almost linearly to failure. To obtain the most out of the adhesive capacity, however, the wood framing should be designed with special attention to the connections between framing members and the anchoring of the wall's base plate. These details control the capacity of the frame to sustain the loads induced by the stiffer adhesive joints. Key words: adhesive, earthquake, tests, timber construction, shear walls, wood.
Mathematical modelling of riverbed dynamics – a Canadian case study
Authors: Morse B. , Townsend R. D. , Sydor M.
Published: January 2010

A new mobile-bed mathematical model for simulating sediment transport in river networks under unsteady flow conditions is presented. The new model, ONE-D-SED, is an extended version of the extensively validated fixed-bed, one-dimensional hydrodynamic model ONE-D. This paper reports the results of an application of ONE-D-SED to simulate bed profile development along a 43-km-long tidal channel network of the Lower Fraser River in British Columbia. The sand-bed study reach has been undergoing degradation caused by navigational dredging and river training works in lower channel reaches and by borrow dredging within the study reach itself, ONE-D-SED was used to simulate bed degradation in the study reach during the 1979–1984 period. The simulated annual change in bed elevation at the downstream end of the study reach showed good agreement with that observed during 1968, the data year used to calibrate the model. The predicted cumulative change in bed profile from 1979 to 1984 also compared favourably with the overall degradation pattern observed during that same period. Key words: mathematical model, simulation, sediment transport, river network, finite difference, model validation.
Parametric study of design variations on the vibration modes of box girder bridges
Authors: Cheung M. S. , Megnounit A.
Published: January 2010

Under a moving load, a bridge undergoes deflections and stresses which significantly exceed those caused by the same load when applied statically. These dynamic deflections can cause discomfort to pedestrians using the bridge, since human response is sensitive to accelerations and to the rate of change of acceleration. Another factor affecting human response is the type of vibration in the dominant mode. People tend to react more adversely to torsional modes of vibration than to flexural modes. This paper summarizes the results of an extensive analytical investigation, which was conducted to identify key parameters affecting the changes of dominant mode types and to study the influence of diaphragms and cross bracings on dynamic responses of a twin box girder bridge. The finite element method was used to carry out these analyses. The analytical results indicate that the provision of diaphragms within the boxes at each support, or of a cross-bracing system in-between boxes, can effectively reduce peak accelerations when the dominant mode of vibration is torsional. As a result, the human discomfort and perception to vibration can be improved. Key words: vibration, human response, torsion, flexure, box girder bridge, diaphragm, cross bracing, finite element analysis.
Accelerated testing of a filled polyester E-glass composite in acidic environments
Authors: Woytowich David L. , King Martin W. , Britton Myron G. , Oleszkiewicz Jan A.
Published: January 2010

This paper describes the results of an accelerated laboratory investigation to measure the rate of deterioration of a newly developed filled plastic composite exposed to acidic (sewage) environments. The specific objective was to compare the relative rates of deterioration of an experimental filled filament wound (FFW) polyester composite immersed in sulfuric (pH 2.23) and acetic (pH 2.22) acid environments at 45 °C. Deterioration was measured in terms of changes in wet specimen weight, loss in dried (soluble) material weight and mechanical properties, the extent of chemical dissolution, and the depth of penetration. Based on regression analyses of these parameters, it was found that the rate of deterioration was a function of the square root of immersion time. Deterioration of the FFW composite in acetic acid was 1.6–3.9 times greater than in the sulfuric acid environment. The loss in wet flexural properties and the dissolution behavior of aluminum trihydrate were not influenced by the type of acid environment. Based on the findings of this study, sulfuric acid is recommended as a standard laboratory test medium for fiberglass reinforced plastic composites used in construction of sewage facilities and pipelines where deterioration due to sulfur oxidizing bacteria is anticipated. Key words: accelerated, polyester, fillers, filament-wound, environment, acidic, durability, composite, septic tanks.
Monitoring wells: measurement of permeability with minimal modification of groundwater
Authors: Chapuis Robert P. , Wendling Gilles
Published: January 2010

It is important to verify whether a monitoring well has been correctly sealed in the ground in order to avoid vertical cross-communication between aquifers and thus prevent misleading results for the piezometric level and the degree of contamination. This may be done with an in situ falling-head permeability test. A monitoring well is used to sample groundwater, so it is not recommended to introduce a different quality water to perform the permeability check test. The test should be performed preferably with the local groundwater. A method is described in which a stainless steel and teflon bladder pump, a packer, a water pressure transducer, and a field computer are used to perform a falling-head permeability test. Many test results can be stored in the field computer before transferring its data into a microcomputer. The results may then be presented in the form of tables and graphics to determine the hydraulic conductivity of the tested layer, and to verify whether the installation of the monitoring well is correct. Results of field tests are presented to illustrate this method. Key words: groundwater, contamination, permeability, monitoring.
Some characteristics of high-strength structural concrete
Authors: Bickley J. A. , Ryell J. , Rogers C. , Hooton R. D.
Published: January 2010

The 68-storey Scotia Plaza tower in Toronto is an outstanding example of the use of concrete technology to achieve high-performance high-strength concrete. Cementitious hydraulic slag, silica fume, and a superplasticizer were combined with CSA type-10 Portland cement and high-quality aggregates to produce very workable high-strength concrete. During the course of construction, data were published suggesting the possibility of the strength regression of some silica fume concretes after long exposure to low humidity, the determinations being made on standard test cylinders. Tests were, therefore, made at ages of 1 year and 2 years on specimens drilled from columns in the structure. This technical note gives details of the laboratory examination and testing of these specimens. Key words: high strength, slag, silica fume, permeability, rapid chloride permeability, petrographic examination, superplasticizers.
Significance of building and plumbing specifics on trace metal concentrations in drinking water
Authors: Singh Inderjit , Mavinic Donald S.
Published: January 2010

Samples were taken from 72 high-rise apartment suites (6 suites in 12 individual high-rise towers) and 60 single-family houses located within the Greater Vancouver Regional District. The influence of the following factors on trace metal concentrations in 1-L first-flush drinking water samples and “running” hot water samples was investigated: building height, location, plumbing age, type of plumbing, and type of building. Results of this survey show that with the exception of building height, all factors had a correlation with one or more of the trace metals investigated. The trace metals examined were lead, copper, iron, and zinc. Lead was influenced primarily by building type, copper by plumbing age and type of plumbing, and iron by location. Elevated lead levels were associated with high-rise samples. New copper plumbing systems resulted in high copper levels. Highest iron levels in the drinking water were measured in the East Vancouver location. Zinc did not show a distinct correlation with any of the factors investigated. Brass faucets were the primary source of zinc in tap water. They also contributed substantially to the lead detected in the 1-L first-flush sample. Metal concentrations measured in the high-rise and house samples were compared with the U.S. Environmental Protection Agency's (USEPA) maximum contaminant levels (MCLs) and the proposed “no-action” level for lead. In high-rise samples, the 0.01 mg/L “no-action” level proposed for lead was exceeded in 43% of the samples, and 62% of the samples exceeded the current 1.0 mg/L MCL standard for copper. In single-family house samples, these values were 47% and 73%, respectively. The average lead concentrations were 0.020 mg/L for all high-rise samples and 0.013 mg/L for house samples. Regulatory levels stated above would still be exceeded in 6% of the cases for lead and 9% of the cases for copper, even after prolonged flushing of the tap in a high-rise building. In all cases associated with single-family houses, flushing the cold water tap for 5 minutes was successful in achieving compliance levels. Key words: aggressive water, compliance, corrosive, drinking water, first-flush, GVRD, high-rise, single-family house, trace metals, USEPA.
Longitudinal floating structures – new concepts in river ice control
Authors: Calkins Darryl J.
Published: January 2010

Ice control structures placed in the streamwise direction of a river were analyzed to determine the effectiveness in reducing ice jam thicknesses. The theory describing the thickness for “wide” river ice jams was modified to analyze these longitudinal types, providing the computational verification that ice jam thicknesses could be reduced where the mode of ice cover thickening is internal collapse. These longitudinal structures appear to provide a new tool for modifying the river ice regime at freeze-up and possibly at breakup. By decreasing the ice jam thicknesses, which leads to lower stages, the structures have the potential for decreasing ice jam flood levels. The structures' ability to function is independent of the flow velocity and these structures should perform in rivers with velocities greater than the usual limitation of roughly 1 m/s associated with conventional cross-channel ice booms. Other possible applications include controlling ice movement at outlets from lakes, enhancing river ice cover progression, or even restraining the ice cover at breakup. A U.S. patent application has been filed jointly by the author and the U.S. Army Corps of Engineers. Key words: river ice, ice jams, ice control, hydraulic structures, ice booms.
Punching shear analysis of reinforced high-strength concrete slabs
Authors: Marzouk H. , Hussein A.
Published: January 2010

An experimental investigation was conducted at the structural laboratory at Memorial University of Newfoundland to examine the behaviour of high-strength concrete two-way slabs. It was evident that a new mechanical model is required to predict the punching shear capacity of such slabs. The experimental results of the tested slabs with regard to deformations, strains, ultimate capacity, and modes of failure were examined. Based on the test results, a mechanical model was adopted and developed for high-strength concrete slab applications. The formulation takes into account the actual behaviour of the high-strength concrete and steel. The proposed model gives a fairly good agreement between the predicted and experimental punching loads. Key words: deflections, deformations, failure mechanisms, flat concrete plates, high-strength concrete, loads (forces), mechanical model, punching shear, reinforced concrete.
A proposed dynamic foundation factor for the National Building Code of Canada
Authors: Elhmadi Kamel , Heidebrecht Arthur C.
Published: January 2010

Results of a parametric study on site response effects due to seismic strong ground motions are used in this paper to develop a new "dynamic foundation factor" for the National Building Code of Canada. In order to capture the effect of the site resonance, the proposed dynamic foundation factor, F*, is given as a function of the ratio between the fundamental period of the building and the site period, T/Ts (i.e., F* spectra in terms of T/Ts). The parametric study results suggested that the proposed F* spectra be dependent on four different classes of soil deposits. These classes are deep cohesive (class 1), deep cohesionless (class 2), shallow cohesive and cohesionless (class 3), and dense sand (class 4). For classes 1 and 2, the F* spectra are independent of the ratio of peak acceleration to peak velocity, av, of the seismic ground motion. For classes 3 and 4, however, the F* spectra are an increasing function of the ratio a/v. A scaling multiplier is introduced to take into account the influence of level of intensity, v. The proposed dynamic foundation factor is compared with the National Building Code of Canada 1990 foundation factor. Finally, actual sites are used to check the validity and consistency of the proposed dynamic foundation factor. Key words: seismic, foundation factor, soil, site, amplification, building, shear, force, period, spectra.
Limit states criteria for structural evaluation of existing buildings
Authors: Allen D. E.
Published: January 2010

Difficulties have been encountered in applying the requirements in the National Building Code (NBC) and referenced CSA standards to the structural evaluation and upgrading of existing buildings in Canada. The Associate Committee of the NBC has therefore initiated an effort to provide guidelines on the application of Part 4 of the NBC to existing buildings, allowing alternative requirements where needed. As an initial step towards fulfilling this goal, this paper reviews all aspects of limit states criteria for structural evaluation and proposes minimum load factors based on a life safety criterion. The proposed load factors allow more flexibility in practice but require more professional judgment. Key words: existing buildings, structural evaluation, criteria.