bluuebunny/crossref_metadata_2025 huggingface dataset:
Ozone disinfection of primary effluent using a stirred tank reactor
Authors: Caverson D. L. , Finch G. R. , Smith D. W.
Published: January 2010

A pilot-scale stirred tank reactor was used to evaluate the efficiency of ozone for disinfecting primary effluent. Total and fecal coliform numbers before and after disinfection were evaluated concomitant with several common wastewater characteristics. A disinfection model was built using the method of linear least squares. The model enables the designer to choose the transferred ozone dose to achieve a given number of indicator bacteria in the effluent when the BOD5 is known. The model was found to be useful for the primary effluent studied but should not be used in other applications without pilot plant investigations. Examination of similar models reported in the literature suggests that weak wastewaters (COD < 25 mg/L) may be described by a regression model using COD and transferred ozone as variables but extrapolation to moderate and strong wastewaters, as was done in this study, introduced gross errors. Further research into the fundamental kinetics of ozone disinfection of wastewater is necessary before a reliable design model is available. Key words: ozone, disinfection, primary eflluent, model, coliforms.
Design strengths of steel beam–columns
Authors: Trahair N. S.
Published: January 2010

Some of the present Canadian rules for designing steel beam–columns can be improved if different formulations are used for designing against in-plane failure and out-of-plane buckling. An extension of the present use of nonlinear elastic analysis methods allows a common formulation for the in-plane strengths of braced and unbraced beam–columns, and generally leads to predictions that are more accurate than the present forms. Two alternative methods are developed for improving the design rules for estimating the out-of-plane strengths of beam–columns. The first of these retains the present familiar form, while the second uses a new form that will lead, in some cases, to significant economies. A method is also proposed for combining the separate formulations for the in-plane and out-of-plane strengths in order to estimate the biaxial bending resistances of beam–columns. Key words: beams, buckling, columns, flexure, steel, structural design, structural engineering, torsion.
System identification of civil engineering structures
Authors: Béliveau J.-G.
Published: January 2010

The comparison of measured dynamic characteristics or response of large structures with that of an appropriate finite element model with all its underlying assumptions often reveals discrepancies. This may be due to improperly determined parameters, such as interstory stiffness, mass of different stories, and the modulus of elasticity of the concrete, as well as the inadequacies of the model.The measured dynamic response generally occurs in one of three forms: time response, frequency response, and modal data. For time response data, either in free vibration or for a known input, parameters are estimated by proper adjustments to match more closely the measured motion. For steady-state frequency response, a sinusoidal load (or synchronized loads) is input mechanically and the response, both in amplitude and in phase, is measured for different frequencies of excitation. Damped resonant frequencies, the associated modal damping ratios, and the corresponding mode shapes are the measured quantities for modal data.The finite element models used for civil engineering structures often incorporate a large number of degrees of freedom. Measured response is sparse and usually limited to the lower frequency range. A procedure for estimating these parameters must be able to allow for the small amount of data and must utilize efficient numerical algorithms to determine the best parameters. Nonlinear least squares, within a Bayesian framework, is such a method. It can be applied to time-history data, steady-state response, and modal characteristics. This method is used to determine aerodynamic coefficients of a scale model of a suspension bridge deck from free response data in a wind tunnel, stiffness parameters from frequency measurements of a 5-story steel building frame loaded by mechanical exciters on the roof, and stiffness parameters from modal data of a 12-story reinforced concrete frame, as obtained from transient wind observation of lateral accelerations.
Full-scale load test of three-span concrete highway bridge
Authors: Scanlon Andrew , Mikhailovsky Leonid
Published: January 2010

A full-scale load test to failure of a 34-year-old three-span continuous reinforced concrete highway bridge located in southern Alberta is described. The opportunity to load test the structure to failure occurred as a result of the scheduled demolition of the bridge.Load was applied to the structure in two phases. In the first phase, precast concrete sections were placed at the centre of the middle span until a load of approximately 1900 kN was reached. At this load level a mid-span deflection of 28 mm was measured for the interior span. Additional load was applied by jacking the ends of the bridge at the abutment supports. Loading continued until a maximum deflection of 157 mm was reached at mid-span. Significant cracking as well as crushing of the compression flange at mid-span were evident. On removal of load at mid-span, a residual deflection of 118 mm was observed indicating that the bridge had been loaded well into the postyield range without collapsing.Results of the test are presented in the form of plots of load vs. deflection, reactions vs. deflection, mid-span moment vs. deflection, and deflection profiles at various loading stages. In addition the calculated flexural capacity is compared with measured values. Key words: highway bridge, load test, reinforced concrete.
Swedish field experiences with chemical precipitation in stabilization ponds
Authors: Hanaeus Jorgen
Published: January 2010

Historically, sewage treatment in Sweden shows a development towards the construction and use of package plants. These package plants, however, present several problems associated with flow and temperature.Year-long studies of chemical precipitation using slaked lime in stabilization ponds have demonstrated an overall reduction of organic matter (as COD (chemical oxygen demand)) of about 75% to a level somewhat below 100 mg/L, and a reduction of total phosphorus of 90% to approximately 0.7 mg/L as P. These values were reached under ordinary operating plant conditions. No efforts to optimize the process were made. Chemical precipitation treatment using slaked lime has shown good bacterial reduction at the high pH values obtained.Two tracer studies using Rhodamine B dye have demonstrated the appearance of strong short-circuiting flows in pond systems and the inserting of simple baffle walls in the pond has been recommended. Dewatering the sludge in the ponds by natural freezing has proven to be an excellent process, as the time for collecting sludge can be chosen almost arbitrarily during the year.The lack of design guidelines, especially with respect to detention time, is rather obvious. The conventionally used design criteria for pond surface area design have proven to be inadequate. Key words: sewage treatment, stabilization ponds, chemical precipitation, phosphorus removal, tracer, sludge treatment.
Évaluation du potentiel de la télédétection spatiale pour l'étude du milieu urbain : le cas de Montréal
Authors: Carignan M. , Morin D. , Brochu R. , Royer A.
Published: January 2010

Satellite imagery in multispectral mode actually available is provided by MSS (multispectral scanner) and TM (thematic mapper) sensors aboard the American satellite LANDSAT-5. Potential use of this type of data for study of the urban environment is quite relevant, as it associates speed of analysis with competitive cost.Using as an example the study of the Montréal, Quebec region, enhanced color composite image production demonstrates the possibilities of TM data in the photo-interpretation of urban characteristics owing to better spatial resolution. On the other hand, the thematic analysis of land units using automatic classification techniques for cartographic purposes gives five land-use classes. These correspond quite well to the classification used by urbanists for major urban functions. The mean accuracy in terms of area is in the order of 97% for the total of urban areas and 75% for each class.
The use of snow-pillow data for melt rate input to the streamflow synthesis and reservoir regulation watershed model
Authors: Ferner S. J. , Wigham J. M.
Published: January 2010

A split watershed version of the streamflow synthesis and reservoir regulation (SSARR) model was calibrated and verified for Marmot Creek, a small forested research watershed located in the Rocky Mountains west of Calgary, Alberta. The model is used for forecasting runoff rates. Melt-rate data from five snow pillows, located at sites of different elevation and exposure on the basin, were applied to the model. The melt-rate factor expressed in millimetres per degree-day was the only input parameter changed in the model, which was run for the months of April, May, and June over an 8-year period, 1973–1980.An average melt rate from the snow-covered area as determined from the five snow pillows provided the best runoff simulation. Measured melt rates from just one snow pillow, located at the middle elevation of the basin in a heavily forested area, provided a comparable simulation. Snow pillows located at lower elevations in either open or closed areas and snow pillows located at higher elevations in open areas yielded poor simulations. The characteristics and problems associated with the use of snow pillow for modelling snowmelt are also discussed. Key words: snowmelt, snow pillows, watershed models, runoff forecasting.
Étude expérimentale sur les poutres mixtes
Authors: Lachance L. , Picard A. , Michaud Y.
Published: January 2010

This paper presents a summary of the first part of a general research program on the nonlinear theory of composite beams and columns. The paper deals with the experimental study of simply supported composite beams, submitted to uniaxial bending about the major axis. Test results are compared with theoretical results obtained from an elaborate nonlinear analysis.A total of eight composite beams have been tested, four of them with special dowels welded to the wide-flange section web, and steel plates welded at both ends, in order to limit sliding between steel and concrete.By adequately adjusting the concrete stress–strain curve measured on control cylinders, to take into account the effects of strain rate, strain gradient, and steel reinforcement confinement, we obtain a theoretical ultimate bending moment identical to the experimental moment, and a deflection at rupture 10% smaller than the measured one. Key words: reinforced concrete, stress–strain curve, bending, ultimate moment, ultimate deflection, nonlinear theory, composite beams, composite sections.
Onset of sediment motion under waves and currents
Authors: Quick Michael C. , Kingston Kristopher , Lei Shenglong
Published: January 2010

Experiments have been made to study the resultant flow field and bed shear stress produced by the combination of surface waves and steady currents. Comparison has been made between the sediment threshold flow conditions for steady flow, for waves alone, and for combined waves and currents. Experiments, using a laser Doppler anemometer and sediments sieved into narrow size ranges, show that a similar maximum velocity condition, close to the bed, causes onset of motion for all the conditions tested. This maximum velocity can be calculated from the Manning equation, the log velocity law, and second-order wave theory, if it is assumed that the near-bed maximum wave and average current velocity at one roughness height above the bed combine linearly. It is demonstrated that the Shields threshold criterion can be extended to both the wave and combined wave plus current situations. The maximum velocity at approximately one roughness height above the bed is therefore shown to be a good general criterion, which can also be used to estimate the probability of sediment motion. Key words: waves and currents, sediment transport, coastal erosion.
Design methods for partially prestressed concrete—a review
Authors: Shahawi M. El , Batchelor B. deV.
Published: January 2010

Methods for use in the flexural analysis and design of a partially prestressed concrete section are outlined. A typical design example is presented and the results obtained by different design methods are compared. Methods proposed by Moustafa, Naaman and Siriaksorn, Bachmann, and Nilson are all suitable for design purposes. The graphs developed by Moustafa are useful in expediting design. The method proposed by Abeles, which is based on the use of a fictitious tensile stress in the concrete, is generally not recommended. Key words: concrete (prestress), design, flexure, partial prestressing.
Analysis of beams with large openings using nonlinear finite element procedure
Authors: Al-Manaseer A. A. , Nasser K. W.
Published: January 2010

The object of this paper was to use a nonlinear plane stress finite element procedure to predict the behaviour of simply supported reinforced concrete beams with a large opening, under mid-span static loading. In the finite element analysis, parabolic isoparametric elements were used in conjunction with the discrete bar formulation. A smeared cracking approach was included and concrete under different states of stress was modelled by using individual models that were incorporated to represent a biaxial state of stress. Reinforcing steel was modelled by using a uniaxial elastoplastic strain-hardening curve. Test results showed that the above approach was found to be satisfactory in predicting the load–deflection curves, crack patterns, and ultimate loads for this type of beam. Key words: beams, cracking, endochronic theory, finite element method, load deflection, nonlinear analysis, openings, reinforced concrete, ultimate load.
Effect of architectural components on the dynamic properties of a long-span floor system
Authors: Pernica G.
Published: January 2010

Vibration measurements were taken to determine the effects of architectural components on the dynamic properties (modal frequency, modal damping ratio, and mode shape) of a long-span floor system. The floor was located above a two-storey gymnasium in a recently constructed three-storey elementary school. The dynamic properties of the bare floor system were measured during the construction phase, immediately after the main structural components and the exterior masonry walls were in place. Six months later, with construction completed and the school ready for occupancy, the properties of the finished floor system, complete with internal partitions, mechanical ducts, furnishings, and carpeting, were again obtained.A comparison of the results of the two test series indicated that the dynamic properties of the floor system were altered by the addition of the architectural components. The fundamental frequency rose by 3% and the frequencies of the higher modes by 23%, even though the static load on the floor increased by about 26%. The substantial stiffening of the floor system necessary to precipitate these increases in frequency was linked to the presence of the internal partitions. A full-span partition was also found to behave as a floor support, creating an additional set of modes which were not previously present. Except for the fundamental mode, damping ratios increased by about 2% of critical, from 1.5% to 3.5% of critical. For the fundamental mode, the negligible increase in damping from 4.1 to 4.2% of critical could not be explained. Key words: floors, composite structures, vibration tests, spectrum analysis, resonant frequency, vibration damping.
The effect of roadway salting on safety and mobility
Authors: Braaksma John P. , Ridley Robert C. , Jones Philip H.
Published: January 2010

The research detailed in this report represents a preliminary effort to develop an understanding of the effects of roadway salting on road safety and mobility.Analyses included an assessment of available literature, the review of accident data from a number of sources, and the development of a study procedure for assessing the effects of winter conditions and maintenance activities on vehicle operations. The procedure developed was based on vehicle headway observations.Field trials of the study procedure in six different jurisdictions confirmed it to be sensitive to roadway conditions, and to be capable of reflecting the effects of maintenance activities. Results of the studies showed little variation for mean headways under dry, wet, and slushy road conditions. Mean headways under show or icy road conditions were much larger. Limited study of the effects of maintenance activities suggested that different roadway salting strategies had little differential effect on vehicle headways. Finally a variety of study refinements were identified.Analyses of accident data was not conclusive with data from the 11 jurisdictions reviewed showing remarkable consistency in the proportion of accidents experienced under winter versus nonwinter conditions. This consistency was unexpected in view of the variations in weather conditions, maintenance strategies, and metropolitan characteristics of the study group. Key words: salt, snow, ice, sodium chloride, level of service, winter maintenance, deicers, and snow and ice control.
Load capacity of uniformly compressed cold-formed steel section with punched web
Authors: Sivakumaran K.S.
Published: January 2010

Load tests were carried out on 48 stub column specimens of cold-formed steel sections having flat widths of 82.5 and 144.7 mm, thicknesses of 1.60 and 1.29 mm, respectively, and various sizes and shapes of holes punched through their webs. This paper summarizes the experimental local buckling loads, ultimate loads, load–axial shortening relationships, and load–out-of-plane deflection relationships of the above specimens. Presently, the Canadian design code does not include any provisions in regards to the design of perforated cold-formed sections, owing to the lack of experimental results. A design approach using the present code "effective design width" for unstiffened elements is explored and the observations resulting from the comparison between the calculated values and the experimental values are given. The new American Iron and Steel Institute design specification gives an effective design width for cold-formed section with circular perforations. The appropriateness of this equation when applied to circular, square, and elongated openings is discussed. It appears that the design provisions of both codes are inadequate for the design of perforated cold-formed steel sections and further research is needed in this area. This is essential, considering the fact that, in practice, the cold-formed members often contain prepunched holes. Key words: axial load, buckling, building codes, cold-formed steel, effective design width, perforation, ultimate loads.
Auto-determination of ice forces on arctic structures
Authors: Brown T. G. , Cheung M. S.
Published: January 2010

This paper describes a variety of programs specifically designed for the determination of sea ice and iceberg loads on Arctic offshore and nearshore structures. As any ice load is a function of the interaction between ice feature and structure, the design of arctic structures is very much an interactive process. Many other factors determining the overall loads and local pressures are functions jointly of ice feature and structural characteristics. For example, the ice strain rate which is a primary determinant of ice strength and failure behaviour may be determined from ice velocity and structure size.The paper details the development of a number of programs directed at the evaluation of quasi-static ice loads, dynamic ice loads, and corresponding local pressures between ice and structure. Examples are provided of the use of the various programs, including the data required and the type of outputs resulting.As a number of the programs incorporate quite extensive theoretical developments or, in one case, a large number of discrete interactions, full description of each program is beyond the scope of this paper. The reader is directed to the listed references for full developments of the various programs and algorithms. Key words: sea ice, iceberg, global ice load, local ice pressure, finite element, ice/structure interaction, probabilistic analysis, ice failure mode.
The driver population factor and its influence on highway cost–volume curves
Authors: Sharma Satish C.
Published: January 2010

The Highway Capacity Manual is a publication widely used throughout the world as a guide to highway capacity and level of service analysis. The third and the latest edition of the Manual, a 1985 publication of the United States Transportation Research Board, has introduced, among many other changes, an adjustment factor called fp to reflect the influence of driver population on the highway capacity analysis for freeways and multilane highways. This note reviews and elaborates on the driver population factor. As a prerequisite to an appropriate application of the factor fp, this note refers to a systematic and objective method that can be used for classification of highways according to driver population characteristics. By taking an example of the road classes in Alberta, the note suggests a set of fp values that can be used as a guide to exercise an engineering judgement in selecting a specific fp value for a particular type of traffic stream. Also included in this note is a brief economic analysis carried out with an objective of determining the importance and sensitivity of the factor fp in transportation analysis. Key words: cost–volume curves, driver population factor, economic analysis, highway capacity, road classification, traffic stream characteristics.
Glulam rivet connections under eccentric loading
Authors: Karacabeyli Erol , Foschi Ricardo O.
Published: January 2010

Results from theoretical and experimental studies on the strength of glulam rivet connections under eccentric loading are presented. Two failure modes are studied: (1) rivet yielding in bending with simultaneous bearing failure of the wood under the rivet's shank and (2) wood failure around the rivet cluster. The latter is studied using brittle fracture theory and a finite element analysis of the stress distribution in the wood around the rivets.Experimental results are shown to compare well with theoretical predictions for failure loads and type of failure, and design guidelines are proposed. Key words: fasteners, wood connectors, glued-laminated, nails, timber engineering.
Reliability of floors under impact vibration
Authors: Foschi Ricardo O. , Gupta Ashwani
Published: January 2010

Uncomfortable vibrations is a serviceability limit state that must be taken into account in the design of residential floors. A finite strip analysis of a floor system, previously developed for static loads, is extended to dynamic problems. This analysis is applied to the problem of transient vibrations set up by a footfall impact, considering two persons on the floor: an impacter and a receiver. The floor response at the receiver's location is utilized in conjunction with human vibration tolerance data to determine a floor dynamic rating. The variability in this rating is assessed as a function of joist stiffness randomness, and a reliability-based design recommendation is developed: it limits the static deflection produced by a concentrated load of 1 kN, acting at midspan of a joist with the mean modulus of elasticity, to a maximum of 1 mm, independent of span length. Key words: vibrations, impact, floors, reliability, limit states design.
Drilled-in inserts in masonry construction under combined shear and tension
Authors: Hatzinikolas Mike , Longworth Jack , Warwaruk Joseph
Published: January 2010

Various types of drilled-in inserts were tested under combined shear and tension loads. Based on the test results and observations, behaviour modes of failure are described. Empirical relationships are established to predict insert capacity and design recommendations are presented. Key words: expansion inserts, adhesive inserts, shear, tension, concrete block, clay brick.
Field evaluation and model test of a composite wing-girder bridge
Authors: Breen John E. , Kreger Michael E. , White Christopher D. , Clark Gordon C.
Published: January 2010

This paper presents the key observations and conclusions from the evaluation of an innovative "loose-fit" composite, post-tensioned concrete wing-girder bridge proposed for an elevated interstate highway expansion in an urban environment. The evaluation program included both testing to destruction of a 1/2-scale model of a partial span as well as construction monitoring and field testing at service load levels of a full-scale prototype two-span bridge. Results of both construction measurements and loading tests were compared with analytical predictions. Laboratory tests showed the composite behavior of the wing-girder joint to be fully effective and a high level of load transfer between wings to be present. Recommendations for modification of the prototype design are made to improve constructibility, durability, structural performance, and economy. Key words: box girder, bridge, post-tensioned, prestressed concrete, reinforcement, stresses, temperature, tendons.
Field measured two-way slab deflections
Authors: Jokinen Eric P. , Scanlon Andrew
Published: January 2010

Results of a survey of two-way slab deflections both during and after construction of a 28-storey office tower are presented. A comparison is made between measured deflections and deflections computed using a finite element program that includes the effects of cracking. Effects of construction loading and time-dependent deformations are included in the calculations. The measured and calculated deflections illustrate the high variability that can be expected in two-way slab deflections. Key words: concrete construction, deflection, finite elements, loads, multistorey construction, two-way slabs, variability.
Laboratory evaluation of solid residues from atmospheric fluidized bed combustion systems
Authors: Constable T. W. , Kissel R. , Sawell S. E. , Cunningham W.
Published: January 2010

Tests and analyses were conducted to characterize the physical, chemical, exothermic, and leaching properties of solid residues from bubbling bed atmospheric fluidized bed combustion units. The residues were produced during the combustion of eastern Canadian high-sulphur bituminous coals (4–8% sulphur) in a bed of eastern Canadian limestone. The residues were highly buffered and composed primarily of calcium and sulphur salts. They were exothermic and swelled considerably when contacted with water. Leachates generated during 20-cycle serial batch leaching tests were highly alkaline with high total dissolved solids concentrations, primarily calcium and sulphate ions. Column leaching test results and field observations suggest reactions may continue to occur over several months until the residues eventually solidify. The residues have properties that are unique, in comparison with conventional pulverized coal combustion wastes. Key words: fluidized bed combustion, ash, leaching.
Spatial and temporal groupings of water main pipe breakage in Winnipeg
Authors: Goulter I. C. , Kazemi A.
Published: January 2010

The spatial and temporal patterns of water distribution pipe failure in the City of Winnipeg are examined. The failures are shown to be strongly clustered in space, where 22% of the total failures examined occur within 1 m of another failure and 46% occur within 20 m of another failure. A strong temporal clustering is also apparent, with 42% of all failures that occur within 1 m of another found also to occur within 1 day of the initial failure in the group. An exponential decrease in the marginal rates of failure with respect to both the temporal and spatial interval parameter is also observed. Earlier failures in a particular location appear to be an important key to assessing potential failures in that vicinity. These results suggest that a fruitful area for further examination for the reduction of failure rates is the change in the ground conditions resulting from an initial leak and its subsequent repair. Key words: failures, groupings, marginal rates, pipes, space, time, water distribution, Winnipeg.
Buckling behaviour of thin-walled columns
Authors: Roorda John
Published: January 2010

This paper describes the interactive buckling behaviour of thin-walled columns by means of a simple engineering analysis. After a brief review of individual column and plate buckling phenomena, the effect of one upon the other is investigated in the presence of initial imperfections. Estimates of the ultimate load capacity of such columns and the effects of material yielding are obtained. The results are compared with published experimental data, yielding good correspondence. The work clearly demonstrates that the interactive presence of Euler buckling, plate buckling, imperfections, and material yielding in thin-walled columns has a serious detrimental effect on their ultimate strength. Key words: buckling, stability, interaction, imperfections, yield, plates, columns, thin-walled, cold-formed, steel, experiments.
Phosphate requirement for anaerobic fixed film treatment of landfill leachate
Authors: Thirumurthi Dhandapani , Groskopf Glenn Robert
Published: January 2010

Three laboratory model anaerobic fixed film reactors, AFFR-A, B, and C, fed by a pretreated leachate, were monitored at 35 ± 5 °C for 10 months to estimate the effects of different concentrations and the forms of phosphate (ortho, organic, or condensed) on performances at 1.2–1.8 g COD/(d∙L) of reactor volume. Ortho phosphate (Na3PO4) supplement was added to the feed of AFFR-A, organic phosphate (sodium glycerophosphate: C3H7Na2O6P∙5H2O) to AFFR-B, and condensed phosphate (Na4P2O7) to AFFR-C at a feed COD/P value of about 6100 for 23 weeks (Phase I). When no PO4 deficiency was observed, the value was increased to 7700 in reactors A and B, but the PO4 supplement was terminated for reactor C, resulting in a value of 64 300 (Phase II). The average COD of C effluent was 599 mg/L as compared to 451 and 442 mg/L for reactors A and B, respectively, suggesting that a COD/P of 64 300 was too high. During Phase III, the COD/P ratios were changed in reactors A, B, and C, respectively, to 10 200, 15 200, and 34 300. The results indicate that the "optimal" ratio of COD/P lies perhaps between 15 000 and 34 300. Anaerobes did not prefer any one form of PO4 over the other two. Key words: anaerobic treatment, phosphate requirement, ortho phosphate, condensed phosphate, organic phosphate, leachate treatment, fixed film reactor.
Evaluation of site-specific seismic design requirements for three Canadian cities
Authors: Heidebrecht A. C. , Naumoski N.
Published: January 2010

Siesmic design requirements as specified in building codes normally use a generic approach in which the seismic response is independent of the site location, except for a single intensity-related parameter used to define the severity of the expected ground motion. In reality, the characteristics of earthquakes that influence structural response depend on both the level of seismic motion and the seismo-tectonic environment at the specific location. This paper describes a methodology for determining seismic design requirements that uses both magnitude (M) and epicentral distance (R) to define the seismo-tectonic environment. Ensembles of actual seismic strong motion records are selected to match the combinations of M and R that dominate the seismic risk at a specific location. These time histories are used to determine both response spectra and seismic response factors (as used in the 1985 edition of the National Building Code, NBCC 1985) for the location in question. This paper applies this methodology to Vancouver, Ottawa, and Quebec City and compares the results with the response spectra and seismic response factors specified in NBCC 1985. The results indicate that a site-specific investigation of seismic design requirements is important in distinguishing between locations having different seismo-tectonic environments. Key words: structures, design, seismic, code, dynamic, acceleration, velocity, spectra, magnitude, epicentral distance.
Field applications of prestressed laminated wood bridge decks
Authors: Taylor Raymond J.
Published: January 2010

The concept of prestressing laminated wood bridge decks was conceived in Ontario in 1976 as a method of upgrading existing deteriorated nailed laminated wood decks. The success of this technique as a method of rehabilitation prompted considerable research and development aimed at introducing it into new construction. This work led to the formation of a comprehensive set of design specifications, which have since been adapted into the Ontario highway bridge design code and were included in the 1983 edition.Since its inception in 1976, the prestressed wood concept has been used many times, and by 1985, more than 16 bridges incorporated the concept in various ways. The objective of this paper is to discuss a number of these field structures in order to demonstrate the flexibility of the prestressed wood deck system. In new construction, the system has been applied to both longitudinally and transversely laminated decks including on-site deck assembly as well as a preassembled deck panel system.The paper describes the applicability of the system, construction sequence, and field problems. In addition, construction costs for some of the applications, as derived from field data, are discussed. Key words: wood, bridges, prestressed wood decks, laminated decks, preassembled deck panels.
Shrinkage behavior of clay liner material exposed to simulated municipal solid waste landfill leachate
Authors: Hettiaratchi J. P. A. , Hrudey S. E. , Smith D. W. , Sego D. C. C.
Published: January 2010

The use of hydraulic conductivity (k) of soil material as the sole basis for sanitary landfill liner design is reviewed. On one hand, k measurements obtained in the laboratory often vary by several orders of magnitude. On the other, laboratory-measured k values fail to address field behavior, where crack formation before and (or) during landfill operation may control the bulk permeability.A synaerisis shrinkage test (SST) to study the soil shrinkage caused by municipal solid waste (MSW) leachates is introduced. Leachates cause soil shrinkage by reducing interparticle repulsive stresses thereby increasing effective stress. The effective stress concept and double layer theory adequately describe the synaerisis shrinkage phenomenon. A strong correlation was obtained between percent strain, the soil–liquid parameter determined from SST results, and a volume change parameter (free swell difference, FSD) from sedimentation test results. The results provide a basis for a broader approach to landfill liner design. The SST, which supplies information on both volume shrinkage and permeability changes caused by leachate, provides a useful laboratory procedure for evaluating liner materials. Key words: clay liners, shrinkage, leachate, synaerisis, hydraulic conductivity.
Cluster analysis as a tool in the classification of structures for safety differentiation
Authors: Ferregut Carlos
Published: January 2010

Different structures and different structural members should reasonably be assigned different levels of reliability to obtain optimum structural performance. This differential assignment of reliabilities or safety parameters is called "safety level differentiation." Up to the present, no simple practical rationale is available for the selection of safety levels. This paper presents a methodology for the selection of safety levels. Cluster analysis is suggested as a tool in the calibration of limit states design codes. The technique may be used to develop importance factors for the design loadings and resistances, reflecting the difference in consequences of failure. The cluster analysis serves to classify a structure according to various attributes that together reflect its social and economic importance. For code specification purposes, it is fundamental to identify which structures in a set are similar, because it facilitates the specification of a single set of code parameters for each structural type, and permits a more rational selection of importance factors. The acceptable number of structural types and the effect of weighing the attributes are also discussed. Some of the new concepts are illustrated using a sample of highway bridges in southwestern Ontario. Key words: safety differentiation, reliability, cluster analysis, code calibration, bridge classification.
Design properties of laterally loaded nailed or bolted wood joints
Authors: Smith Ian , Whale Luke R. J. , Anderson Colin , Hilson Barry O. , Rodd Peter D.
Published: January 2010

This paper summarizes the output from a long-term project commenced in 1980 with the objective of providing reliable knowledge of the mechanical properties of nailed or bolted joints subjected to short-term lateral loadings. Motivation was the development on an international basis of probability-based partial coefficients limit states design codes for structural timberwork. Comparisons are presented between design solutions produced by applying this research and those by the use of contemporary "soft conversion" international partial coefficients limit states design codes that were calibrated from previously available data. Differences relate primarily to design of bolted joints. It is shown that there is an established acceptance in Canada of the approach adopted. Key words: wood, joints, nails, bolts, design.
Note on surface streaking
Authors: Palmer Merv. D.
Published: January 2010

The phenomena of periodic localized high-velocity surface streaks with poor dilution characteristics have been measured in three distinct geographical areas. Statistically the dilution versus time relationships were developed for the surface streaking condition. Key words: surface dispersion, surface jetting, lake dispersion.
Effect of Poisson's ratio and beam spacing on grillage analysis of slab bridges
Authors: Jaeger Leslie G. , Bakht Baidar
Published: January 2010

It is now well established, strictly speaking, that a grillage composed solely of orthogonal beams can be used for the analysis of slab bridges only when the Poisson's ratio (v) of the slab material is taken to be zero. The effect on the various responses of using a grillage composed solely of orthogonal beams, and ignoring v, is discussed in this paper, and a method is given to account for the effect on transverse moments of making this simplifying assumption. The paper also contains procedures to determine the peak values of the various responses, as well as their integrated values over a given width of the bridge. Using these procedures, it is shown that the spacings of grillage beams in the conceptual grillages used for analysis do not influence the results as much as is generally believed. Key word: grillage analogy, longitudinal moment, Poisson's ratio, slab bridges, transverse moments.
Permit vehicle control in Ontario
Authors: Agarwal Akhilesh Chandra
Published: January 2010

Issuing special permits for transportation of large indivisible loads or heavy construction equipment in Ontario is based on the strength of the highway bridges and pavements. The volume of such permit applications has increased many fold over the last 10 years requiring significantly increased effort for their evaluation.The Ontario bridge formula provides a direct relationship between the bridge strength and the regulatory weight limits. Using this relationship, simplified guidelines have been developed to allow speedy evaluation of permit applications without requiring a detailed evaluation of the bridges and pavements enroute. The two-vehicle concept for transporting very long prefabricated components, developed through an in-depth analysis of bridge structures, is included in the guidelines. Over the number of years, the industry has taken full advantage of these guidelines in improving their equipment, making movement of large components a routine matter. This paper summarizes the technical background of these guidelines. Use of the guidelines is illustrated with examples. Key words: transportation, highway bridges, pavements, weight regulations, special permit, truck weights, heavy loads.
Decay of chlorine in diluted municipal effluents
Authors: Abdel-Gawad Shaden T. , Bewtra Jatinder K.
Published: January 2010

Laboratory studies were conducted to develop a model for the overall decay of total residual chlorine (TRC) under various conditions in the natural streams. This model assumes that a portion of the initial chlorine concentration is used to satisfy the immediate chlorine demand and the remainder is subject to gradual decay.The important parameters influencing the gradual decay of TRC, after mixing in the rivers, were found to be photolysis, evaporation, free radical oxidation, temperature, and turbulence. The decay rate is catalyzed by ultraviolet light and increases significantly as the ratio of area to volume of the container increases. The average level of turbulence in streams is found to approximately double the decay rate obtained under quiescent conditions. Key words: residual chlorine, natural streams, decay, evaporation, photolysis, turbulence, temperature effect, municipal effluents.
Design and construction of a prehydrated sand–bentonite liner to contain brine
Authors: Haug M. D. , Barbour S. L. , Longval Pierre
Published: January 2010

The containment of brine in shallow ponds is one of the most serious problems facing waste-management engineers today. Brine waste is produced in many mining and processing operations. It is characterized by high salt concentrations which may seriously contaminate groundwater if not successfully contained. However, brine reacts chemically with clays used in liner construction. As brine permeates the liner, physicochemical interactions between the clay and brine lead to a reduction in volume of the liner. This shrinkage may cause cracking of the liner and the creation of a highly fractured permeable macrostructure.Numerous techniques have been tried to find an effective and economical method of containing brine. Some of these techniques have involved the use of soil, concrete, asphalt, and synthetic liners. However, all of these techniques have major deficiencies in either cost or effectiveness. This paper presents a case study of the first attempt to solve the volume change problem by designing and constructing a sand–bentonite liner prehydrated with brine. The design was based on the results of a triaxial permeability testing program. The results of the testing program and monitoring of the liner since construction indicate that brine prehydration of sand–bentonite liners is an effective technique for use in brine containment. Key words: bentonite, brine, liner, prehydration, containment, waste management, physicochemical effects, clays.
Load distribution in edge stiffened slab and slab-on-girder bridge decks
Authors: Smith K. N. , Mikelsteins I.
Published: January 2010

The results of a study on the effect of edge beam geometry on the static live-load load distribution characteristics of single-span slab and slab-on-girder bridge superstructures are presented. Using a grillage analysis, the influence of various forms of edge stiffening on longitudinal bending moment and vertical deflection at midspan was investigated. Two load cases utilizing the Ontario Highway Bridge Design truck were considered. Of particular interest is the load case of a single vehicle in a travelled lane, as edge beam deflection under this condition is governed by a serviceability limit state design requirement of the Ontario Highway Bridge Design Code.For the bridge geometry and loadings considered, all types of edge stiffening significantly affect edge beam bending moment and deflection at midspan; the effect generally increases as the span decreases. Edge beam bending moment increases as the stiffness of the edge beam is increased. Considering the change in edge beam stiffness, edge beam deflection decreases even though the bending moment carried by the edge beam increases. The results of the grillage analysis agree well with an interpretation of the simplified method of analysis of the Ontario Highway Bridge Design Code. When the deflection criterion is affecting a bridge design, it would be beneficial to account for the edge stiffening. Key words: load distribution, edge stiffening, edge beams, bridge deck analysis, grillage analysis.
Use of seepage meters in a groundwater – lake interaction study in a fractured rock basin — a case study
Authors: Attanayake M. P. , Waller D. H.
Published: January 2010

Applications of seepage meters in lakes with slight bottom sediments in fractured rock basins have not been reported. A study of the hydrogeology of Long Lake, at Halifax, Nova Scotia, used seepage meters in this situation. Fifteen meters were installed in the 1.7 km2 lake — seven in a line extending from the shore, the remaining eight on the lake periphery. Seepage measurements were made monthly over 1 year. Groundwater levels were measured in boreholes in the fractured granite of the watershed. A positive inflow of groundwater to the lake occurred through the year, seepage flux at the shoreline meters varied from 0.15 to 0.78 mL∙m−2∙s−1, with no consistent seasonal variations. Seepage decreased exponentially with offshore distance. A linear relationship was evident between water levels in a borehole near the shore and rate of seepage at the closest meter. Chloride applied to this borehole was reflected in elevated chloride concentrations in seepage collected by the meter. Key words: seepage meter, groundwater – lake system, fractured rock tracers.
Characteristics of sediment loads in Ontario streams
Authors: Dickinson W. T. , Green D. R.
Published: January 2010

This study has involved a literature review and data analysis regarding suspended stream sediments in southern Ontario, highlighting knowledge and identifying gaps with reference to stream loadings, seasonal and areal variability, extreme events, sources of sediments, and sediment and water quality. The quantity of sediment transported in Ontario streams is generally not of major proportion or of major significance. Daily loads follow a distinctive seasonal pattern, the bulk being transported during the spring period; and sediment transport in the province is an event-oriented process, a large percentage of the load moving in a small percentage of time. Extreme events transport a significant portion of the total suspended load, but so also do annual peak events. The bulk of the load emanates from sheet and rill erosion in cropland areas, and areal variability in loads can be related to land use and surface soil conditions. Suspended sediment has been documented to be both a pollutant carrier or source of contamination and a sink or trap for pollutants such as phosphorus, organic compounds, pesticides, and heavy metals. Key words: suspended sediment, loads, temporal patterns, areal variability, extreme values, sources.
Measurements of ridge sails in the Beaufort Sea
Authors: Sayed M. , Frederking R. M. W.
Published: January 2010

Ice pressure ridges in the southern Beaufort Sea near Tuktoyaktuk were surveyed in April 1986. Sail cross-section profiles and ice-block dimensions of ridges of extreme heights were measured at several locations along the outer edge of the landfast ice. Statistical distributions of sail heights as well as correlations between sail dimensions and between ice block dimensions are obtained. Geographical distribution of sail dimensions and longitudinal changes along individual ridges are examined. Key words: ridges, landfast ice, sea ice, ridge sails, ridge statistics, Beaufort Sea.