bluuebunny/crossref_metadata_2025 huggingface dataset:
Considérations sismiques des murs de refend ductiles avec ouvertures
Authors: Chaallal O. , Gauthier D.
Published: January 2010

This paper describes the results of an analytical study of linear and nonlinear behaviour of ductile coupled shear walls with openings, under seismic loading. The walls in a typical building were studied and assumed to be ductile. They were designed, calculated, and detailed in compliance with the National Building Code of Canada 1990 (NBC) and the Canadian concrete code CAN3-A23.3-M84. The results of the elastic analysis show, as expected, that the concentrated force at the top specified by the NBC does not accurately simulate upper-mode effects, at least for this type of structure. A spectral analysis covering the five first modes, as described in the NBC, seems more suitable for coupled shear walls with openings with a period of more than 1.5 s approximately. The results of the nonlinear analysis show that application of the overstrength factor to the wall as recommended by CAN3-A23.3 greatly improves its behaviour and prevents tensile failure of the wall, although it does not always guarantee the desired sequence of plastification in the case of severe earthquakes. Application of the factor does, nonetheless, limit plastification of the wall to lower levels and keeps rotational ductility in beams and walls to a reasonable level. Key words: coupled shear walls, openings, reinforced concrete, ductility, overstrength factor, earthquake, building codes.[Journal translation]
Les évacuateurs de crues en labyrinthe : dimensionnement, fonctionnement, exemples et particularités
Authors: Zerrouk Nacer Eddine , Marche Claude
Published: January 2010

The purpose of this paper is to demonstrate that labyrinth spillways can be a better option than rectilinear ones. The stages that have led to development of the labyrinth spillway are briefly reviewed as are applicable design and calculation principles. Discharge flow diagrams given by Hay and Taylor, Darvas, Lux and Hinchliff, and Magalhaes and Lorena for a trapezoidal labyrinth weir are compared. Calculation procedures and design diagrams were automated, making it possible to study flood routing through a labyrinth spillway and compare its performance to that of an equivalent rectilinear spillway. A real case was used for validation: routing through the trapezoidal labyrinth weir selected for the Keddara Dam in Algeria was compared with routing through the rectilinear spillway of the initial design. Dimensions, discharge values and expected maximum heights show calculated results agree with results of experimental studies of the structure and confirm that technically the labyrinth spillway is an attractive option. Labyrinth spillways can be particularly attractive for upgrading existing developments to satisfy more demanding design flood criteria in the limited right-of-way of an existing spillway. The Sainte Brigitte-des-Saults development in Quebec on the Nicolet Sud-Ouest River is a good case in point. Key words: flood control works, spillway, labyrinth weir, polygonal weir, nonrectilinear weir.[Journal translation]
La combinaison de modèles appliquée à la validation en temps réel des apports naturels aux réservoirs hydriques
Authors: Perreault L. , Bobée B. , Roy R. , Mathier L.
Published: January 2010

The daily net basin supply of the large reservoirs of Hydro-Québec is currently computed by the water balance equation that relies, in particular, on gauge measurements. The number of gauge and their location heavily depend on simplified hypotheses that generate many errors in the computation. Also, for various technical reasons, the daily net basin supply can be missing. These problems greatly affect Hydro-Québec's real-time management of water resources. In this paper, we present a procedure that allows the estimation of the daily net basin supply of Hydro-Québec reservoirs, taking into account the different constraints of real-time forecasting. The approach is based on combined forecasts from two multiple regression models. It appears that this methodology gives good results and constitutes a considerable improvement in comparison with classical models and intuitive procedures usually employed in real-time forecasting. An application of the procedure on the daily net basin supply of three reservoirs (Baskatong, La Grande 3, and Outardes 4) is finally presented and gives satisfactory results. Key words: forecasting, real time, net basin supply, combined forecasts, weighted averages.
Selection of model structure for road accident severity
Authors: Nassar S. A. , Saccomanno F. F. , Shortreed J. H.
Published: January 2010

The presence of rare events in the accident data and transferability of error from one severity level to the other are just two of the issues in modelling accident severity. This paper explores the implications of different model structures and evaluation criteria using a common data set. Evaluation criteria are statistical fit of submodels, stability and validity of risk factors, overall model prediction, and case-specific model predictions. Model structures considered were the sequence of injury severity in the model structure, sequential versus nonsequential models, degree of aggregation, and case control approach. The study concluded that all the different models produce similar results. There is no indication of transferability of error between submodels in the sequential model. It was concluded that a disaggregate model is preferred to an aggregate model given the similarity of results. Key words: road accident severity, personal injury, logit, model choice.
Filtrate turbidity improvement of existing mono-media filters based on a pilot plant study
Authors: Suthaker Supramaniam , Smith Daniel W. , Stanley Stephen J.
Published: January 2010

With the advancement of knowledge in drinking water and health impacts related to it, requirements for drinking water have progressively become more stringent. Removal of particulate matter causing turbidity has also been found to be an effective means for removal of microbial contaminants such as Giardia. The conventional treatment process most effective at removal of small particulates is filtration. Presented is a two-phase pilot-scale study used to select new filter media for the Rossdale Water Treatment Plant in Edmonton, Alberta. The study was necessitated by more stringent turbidity guidelines which existing filters would have difficulty achieving. The design and planning of the study had to consider constraints posed by upgrading of an existing filter facility which dictated the media depth and the allowable bed expansion during backwashing. Phase I involved a screening test of four types of media. Based on the phase I results, a crushed quartz and a dual-media consisting of anthracite and sand were selected for more detailed study in the second phase involving investigation of the effects of filtration rate (3.5–12.5 m/h). Filter performance was analyzed using different statistical methods. Factorial experimental concepts were used to study significant effects. Results from both phases indicated that crushed quartz consistently provided the best effluent quality, while the dual-media provided longer filter runs. Key words: water treatment, constant rate filtration, turbidity standards, filter media, crushed quartz, statistical analysis.
Design wave loads for a jetty at Plymouth, Montserrat
Authors: Isaacson Michael , Allyn Norman , Ackermann Colleen
Published: January 2010

This paper describes the assessment of waves and wave effects with respect to the design of a jetty at Plymouth, Montserrat, in the eastern Caribbean Sea. A previous jetty was destroyed in 1989 by Hurricane Hugo, and a critical part of the new jetty's design relates to the effects of waves. Particular attention is given to the establishment of design wave conditions. This includes both hurricane and non-hurricane conditions and requires a consideration of wave shoaling and refraction, as well as wave breaking in the vicinity of the jetty. The prediction of design wave loads includes the calculation of drag and inertia forces and an assessment of impact loads due to waves on the underside of the jetty and waves breaking onto the deck. Key words: coastal engineering, coastal structures, hydrodynamics, wave forces, wave impact, waves.
Skew composite bridges — analyses for ultimate load
Authors: Helba Alaa , Kennedy John B.
Published: January 2010

The ultimate limit state design for composite skew bridges with slab-on-I-steel girders requires a reliable prediction of their ultimate load capacity. In this paper, the results from a yield-line analysis of prototype composite bridges subjected to OHBDC truck loading are presented and compared with the results from a nonlinear finite element analysis of such prototype skew bridges. The favourable comparison between the two sets of results indicates that the collapse loads of skew composite bridges can be reliably and readily predicted by the yield-line method of analysis. Equations useful for the design and analysis of skew bridges are given. The experimental results from five composite bridge models tested to failure verify and substantiate the analyses. Results of the ultimate loads of six other skew composite bridge models with punched-to-failure deck slabs are also shown. A general and simplified method relating OHBDC truck loading to the collapse load predicted using the yield-line analysis is presented. Key words: analysis, bridges, composite, design, failure patterns, finite element, models, skew, yield-line.
An approximate method for estimation of bending moments in continuous and semirigid frames
Authors: Chikho Abdul H. , Kirby Patrick A.
Published: January 2010

A simple hand method of estimating member bending moments in flexibly connected multistorey frames is presented in this paper. The method allows for semirigid joint action and can be used in conjuction with any of the current rigid methods of frame design. The load factor at elastic instability of flexibly connected frames can be obtained by the proposed method. Also, a procedure for calculating a linearized approximation of the joint stiffnesses in a multistorey frame subjected to vertical and horizontal loads accounting for the nonlinearity of the joint's moment–rotation characteristic is included. Comparison of the prediction of the proposed method with an accurate analysis shows that the proposed method leads to an accuracy that is satisfactory for design purposes. Key words: columns, frames, semirigid connections, steel, structural design.
Introduction des conditions réelles de débit aux limites d'un modèle hydrodynamique
Authors: Robert Jean-Loup , Hamedi Mohammad Hossein
Published: January 2010

The main goal of this paper is to present a technique to improve the specification of discharge at the open boundaries of a hydrodynamic numerical model. Generally, two dimensional models need boundary conditions using imposed values of water level and (or) velocity components. Although these conditions are satisfactory in most situations, they are not sufficient for open channel flow modelling, in which the discharge is set up according to the upstream hydraulic head. The integral form, needed by finite element modelling, is useful to generate explicit boundary terms that, adequately used, allow the introduction of discharge boundary conditions at open borders of the application domain. The theoretical aspects of this approach are first detailed and, to check the validity of the development and to evaluate the reliability of the model as a design tool, the numerical results are compared with observations on an experimental installation. The results allow to conclude that the proposed model offer a wide range of applications and a high level of accuracy and that it can be considered as a useful aid for hydraulic design. Key words: hydrodynamics, free surface flow, modelling, finite elements, discharge law, boundary conditions, numerical-experimental comparison.
Novel application of sulphur metabolism in domestic wastewater treatment
Authors: Basu Saibal Kumar , Oleszkiewicz J. A. , Mino Takashi
Published: January 2010

The feasibility of utilizing the symbiotic relationship of bacteria related to sulphur metabolism was investigated for organic matter removal in a sludge blanket type reactor. The microaerophilic upflow sludge bed reactor (MUSB) relies on the interaction between sulphate reducing bacteria (SRB) and microaerophilic sulphide oxidizing bacteria (SOB), Beggiatoa, for organic matter removal. A five-stage MUSB reactor with a volume of 173 L was operated for 120 days at three hydraulic loadings. The efficiency of the process to remove total-COD (T-COD), filtered-COD (F-COD), and suspended solids (SS) depended on the hydraulic loading. Maximum removals of T-COD, F-COD, and SS were 92%, 94%, and 87% respectively at hydraulic retention time (HRT) of 4.5 h. At a low HRT of 2.5 h, a F-COD removal efficiency of 89% could still be achieved. Although no granulation was observed, a dense flocculated biomass developed which exhibited very good settleability (SVI = 16 mL/g). While the effluent SS increased at the lower HRTs of 3.5 and 2.5 h, the system still operated effectively without a secondary sedimentation tank. Sulphate balance, batch studies, and microscopic examinations indicated the proliferation of SRB and SOB, Beggiatoa, in the biological vessels. Although some COD removal took place by aerobic metabolism in the aeration vessels, sulphur metabolism appears to be the principal mechanism responsible for organic matter removal in the MUSB process. Key words: bacterial symbiosis, sulphur metabolism, microaerophilic upflow sludge bed reactor, sulphate reducing bacteria, sulphide oxidizing bacteria, Beggiatoa.
Near-field mixing at an outfall
Authors: Gawad S. T. Abdel , McCorquodale J. A. , Gerges H.
Published: January 2010

The near-field mixing of effluent from buoyant and nonbuoyant flows from outfalls discharging into a cross-flowing ambient current in trapezoidal channels has been investigated. A physical model was scaled to represent a typical large outfall into one of the connecting channels of the Great Lakes system. The discharged jet was measured in detail to determine the velocity and concentration fields. The excess velocities and concentrations were found to follow the Gaussian distribution. Empirical expressions for the jet trajectories, minimum dilutions, and plume widths were derived. A correction factor has been introduced to the concentration distribution to ensure mass conservation. The calibrated model was verified by comparison with field data and the results of other near-field models (PDS, MIT, and CORMIX). Key words: mixing, near field, pollutant transport, outfall, buoyant flow, non-buoyant flows.
Traitement acide pour la stabilisation des boues d'épuration
Authors: Meunier N. , Tyagi R. D. , Blais J. F.
Published: January 2010

Chemical stabilization of sewage sludge is one of the most researched alternative to conventional biological digestion. The present research was therefore dedicated to studying a new acid treatment process for residual sludge from wastewater treatment, both industrial and municipal. This study demonstrated that sludge acidification (pH = 2.0–2.5) with sulphuric acid brings about a very rapid hydrolysis and mineralization of organic matter of the biomass that causes a significant reduction in sludge solids. This simple and efficient process of acidification for a partial digestion of different types of municipal (primary, secondary, and mixed) and industrial (pulp and paper) sludges could be integrated into the actual chain of treatment and stabilization of sewage sludges. Key words: sewage sludge, stabilization, digestion, acid treatment, sulphuric acid.
Considerations for the design of single-angle compression members attached by one leg
Authors: Temple Murray C. , Sakla Sherief S. S.
Published: January 2010

Angles appear to be one of the simplest of structural elements. Connections, bolted or welded, are easy to make. Despite this, angle compression members are among the most complex structural members to analyze and design. This is because of the end eccentricities of the end connections and because the principal axes of a single angle do not coincide with the axis of the frame or truss of which the angle is a part. Some experimental results are compared with the two generally accepted design procedures. These results are discussed, and hopefully this will aid the designer in selecting a design procedure. Key words: angles, buckling, building (codes), design.
Field performance of thin wall foundations
Authors: Boone Lorne C. , Sego David C. , Dozzi S. Peter
Published: January 2010

The feasibility of building residential basement foundation walls of unreinforced concrete thinner than the conventional 200 mm thick wall is investigated. An optimum thickness of 150 mm was determined for an unreinforced 2400 mm high foundation wall based on the use of equivalent fluid pressures with sand and gravel backfill material. For walls backfilled with other than clean sand and gravel, or with a submerged condition, it was found that the theoretical maximum backfill heights for both 150 and 200 mm walls are substantially less than those presently specified by the Alberta Building Code. The primary purpose of the study described in this paper was to test under actual field conditions the performance of a 150 mm unreinforced concrete wall under varying lateral loads imposed by different soil types, and to compare measured and calculated lateral loads with the equivalent fluid pressure specified as a criterion in the Alberta Building Code. The lateral earth pressures resulting from the backfilling of 150 mm thick concrete foundation walls were investigated for two backfills, namely sandy lean clay (clay till) and sand. The findings indicate that for longer term placement conditions, the resulting pressure distribution supports the hypothesis of a triangular soil pressure distribution and can be described using traditional earth pressure theory. Two design methods based on the concept of equivalent fluid density were evaluated and compared with the field measurements. Key words: thin wall foundations, earth pressure, field measurement.
Wave reflection effects on small craft motions
Authors: Isaacson Michael , Baldwin John , Kennedy Andrew
Published: January 2010

This paper describes an experimental and a numerical study of the wave-induced response of a moored vessel near a reflecting wall, for the purpose of incorporating wave reflection effects into wave agitation criteria for small craft harbours. The motions of a model vessel have been measured for a range of wave heights, wave periods, wave directions, mooring conditions, and vessel locations, and with both regular and irregular waves. These have been compared with the results of a numerical model based on linear diffraction theory. An expression is developed to relate vessel motions near a partially reflecting wall to motions in unreflected waves. This has been found to agree well with the experimental results, and is used to recommend an extension to existing wave agitation criteria for small craft harbours so as to take account of the presence of reflecting walls. Key words: coastal engineering, harbours, hydrodynamics, marinas, wave agitation, waves.
Preliminary studies into the disinfection of potable water using solar radiation
Authors: Shah Surabhi K. , Mcbean Edward A. , Anderson William A.
Published: January 2010

The efficacy and kinetics of water disinfection using solar radiation was studied, with respect to potential household or individual use in regions where treated drinking water is unavailable. Small volumes of sterilized water (1 L or less) were deliberately contaminated with various concentrations of Escherichia coli, and then exposed to solar radiation for several hours with periodic bacterial enumeration using plate count methods. An agar which was selective for fecal coliforms (mFC) was found to be inappropriate in this work as it often gave false negative counts, compared to the nonselective total plate count agar. The die-off of bacteria could be modelled, as a function of cumulative solar dose, in an exponential decay model. Decay rate constants of 0.071 to 0.486 m2∙MJ−1 were estimated. Volumes of 250 mL or less (in a 1 L bottle), and waters with lower bacterial concentrations or higher ionic strength, exhibited higher rates of die-off. Bacterial counts could be reduced from several thousands to less than 1 per millilitre (lower detection limit) during one day of solar irradiation. The source of the water and bottle material had a significant effect on the die-off rate. A Weibull distribution-based model has a conceptually better theoretical basis, and also fits the experimental data adequately at low and high doses. At intermediate solar doses, the Weibull model fit tended to underestimate the bacterial inactivation whereas the exponential decay model overestimated it. While solar disinfection appears useful for bacterial inactivation, it may be ineffective in situations where the major contaminants are the more UV resistant viruses or parasites, or where significant competition from physical or chemical water characteristics exists. It is not likely to be a suitable alternative to conventional chemical disinfection, but may be applicable in situations where no other disinfection is available. Key words: solar disinfection, potable water, coliform bacteria, inactivation kinetics, modelling.
Linear viscoelastic modelling of profiled high density polyethylene pipe
Authors: Moore Ian D. , Hu Fuping
Published: January 2010

Rheological model parameters for a linear viscoelastic finite element analysis are developed for corrugated polyethylene pipes. Relaxation test data from parallel plate load tests on lined corrugated high density polyethylene pipes are used, for pipes deflected to 5% and 10% vertical diameter decrease. Three-dimensional time-dependent finite element analysis is then used to estimate the time-dependent response of a 610 mm diameter pipe subjected to a constant rate of vertical diameter decrease with time. Predictions are obtained for deflection rates varying over three orders of magnitude, for direct comparison with laboratory test results. Small deflection (5%) relaxation rheology leads to good predictions of measured response up to 3% vertical pipe deflection. Large deflection (10%) rheology yields reasonable predictions for pipe response between 3% and 10% vertical deflection. Levels of strain are examined in the pipe profile, and a peak local tensile strain of 0.6% is estimated for the pipe deflected to 3% vertical diameter decrease. The rheological models should permit prediction of response under parallel plate loading for other pipe profiles. These models might also be used for estimation of pipe response under other loading conditions (such as deep burial in the field).
Moored structures in waves and currents
Authors: Isaacson Michael , Baldwin John
Published: January 2010

The present paper provides a brief review of the analysis of moored floating structures in waves and currents. A hydrodynamic analysis is required in order to predict wave and current effects on floating structures, and corresponding numerical models for determining transmitted and reflected wave heights, added masses, damping coefficients, and wave exciting forces are summarized. A mooring analysis is required in conjunction with the hydrodynamic analysis in order to calculate the restraint provided by the mooring system, as well as the structure motions, mooring line and anchor loads, and mooring line configurations. Various aspects of static, dynamic, and nonlinear responses are discussed and illustrated with example applications. Key words: coastal engineering, currents, floating structures, hydrodynamics, mooring forces, ocean engineering, wave forces, waves.
Effect of guy initial tension on design of guyed antenna towers
Authors: Wahba Yohanna M. F. , Madugula Murty K. S. , Monforton Gerard R.
Published: January 2010

This study examines the effect of changing the initial guy tension on the design of guyed antenna towers. Six different guyed towers with various heights and loading conditions are used in this study, in which initial guy tensions are changed and the corresponding effect on the forces in the tower components are examined. Also, the methods used in measuring the initial tension are reviewed. On the basis of this study, it is proposed that the initial guy tensions have a load factor different from the value of 1.0 suggested in CSA S37-94. Two additional load combinations are developed from this analysis in order to assist design engineers in determining the worst case scenario for the variation of initial tension in the guys. Results are compared for designs using the current design procedures and the design using the proposed load factors for initial tensions in guy wires. Key words: antenna towers, guyed towers, limit states design, guys, initial tension.
Pilot and model studies of toxic organic compounds in municipal sludge digestion
Authors: Parker W. J. , Monteith H. D. , Melcer H.
Published: January 2010

The removal of selected toxic compounds during anaerobic and aerobic digestion of municipal sludge was investigated at pilot scale. The candidate compounds included a mixture of cresols, chlorophenols, heterocyclic nitrogenous compounds, phthalates, and polyaromatic hydrocarbons. A wide range of responses of the candidate compounds was observed in anaerobic digestion with seven compounds removed at efficiencies greater than 90% in primary digestion, four compounds demonstrating removals of greater than 80% after secondary digestion, and five compounds demonstrating overall removals of less than 70%. The secondary digester demonstrated a substantial capacity to attenuate toxics. In aerobic digestion, all of the compounds except the cresols, 2, 4, 5-trichlorophenol, and bis-2-ethylhexylphthalate were essentially eliminated. A dynamic model, developed to predict the fate of toxics during primary sludge digestion, was calibrated with data from the experiments. Biodegradation rate coefficients only could be estimated because of statistical redundancy of the sorption partitioning parameter during the nonlinear regression. The sorption partition coefficients were estimated using octanol–water partitioning coefficients from literature. Key words: anaerobic, aerobic, municipal sludge digestion, toxic organic compounds, biodegradation rate coefficients, model, dynamic.
Thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures
Authors: Lie T. T. , Kodur V. K. R.
Published: January 2010

For use in fire resistance calculations, the relevant thermal and mechanical properties of steel-fibre-reinforced concrete at elevated temperatures were determined. These properties included the thermal conductivity, specific heat, thermal expansion, and mass loss, as well as the strength and deformation properties of steel-fibre-reinforced siliceous and carbonate aggregate concretes. The thermal properties are presented in equations that express the values of these properties as a function of temperature in the temperature range between 0 °C and 1000 °C. The mechanical properties are given in the form of stress–strain relationships for the concretes at elevated temperatures. The results indicate that the steel fibres have little influence on the thermal properties of the concretes. The influence on the mechanical properties, however, is relatively greater than the influence on the thermal properties and is expected to be beneficial to the fire resistance of structural elements constructed of fibre-reinforced concrete. Key words: steel fibre, reinforced concrete, thermal properties, mechanical properties, fire resistance.
A model for the environmental screening of highway projects
Authors: Innes J. D. , Pugh E. D.
Published: January 2010

Environmental impact assessment has become an important aspect of the highway planning process. Projects often require approval of both the federal and provincial governments. There is a case for developing a consistent approach to the screening of projects. Several methods of documenting and illustrating screening information have been developed but none define the information required to make a screening decision. This can result in a great deal of subjectivity within the process. In this paper, a standardized screening model for highway projects is developed to address these needs and shortcomings. The model can be used to evaluate the project from a variety of environmental aspects. The model assists the highway planner in defining the screening information requirements and determining whether a specific constraint is of concern, warrants further study, or is not applicable. The paper evaluates the potential utility of the model by applying it to three divergent environmental aspects of highway projects. Key words: highway, planning, environment, impacts, assessments, regulation, fur, archaeology, slates.
Determination of the dynamic characteristics of the Colquitz River Bridge by full-scale testing
Authors: Ventura C. E. , Felber A. J. , Stiemer S. F.
Published: January 2010

This paper presents the results of full-scale tests performed at the Colquitz River Bridge near Victoria, British Columbia (B.C.), Canada, during September 1992 to determine the dynamic characteristics of the structure. The five-span bridge was completed in 1954 and is part of the Trans-Canada Highway. It is 82.68 m long and 11.89 m wide, and has six continuous steel girders supporting a 175 mm thick concrete deck. This particular bridge was chosen for testing because of its typical nature of many B.C. bridges, its location in an area of high seismic risk, and its excellent site accessibility. The tests included extensive measurements of ambient vibrations induced by traffic and other sources to determine the dynamic characteristics of the bridge. The most significant vertical and lateral mode shapes and associated periods of vibration were determined from vibration measurements at more than 50 different locations of the deck, piers, and abutments. Although a large amount of data were collected, they were quickly processed and analyzed with an innovative system developed at The University of British Columbia. One of the important features of this system is that it permits the identification of the principal modes of vibration immediately after the data have been collected. In addition to the ambient vibration tests, quick release pullback tests were conducted to verify modal frequencies determined from the ambient vibration tests and to determine the damping of the fundamental modes. These tests consisted of loading the bridge at a selected location with a force of about 90 kN and then releasing this load very quickly to induce free vibrations. The information obtained from the field tests was used to refine a computer finite element model of the bridge, which, in turn, was used to gain insight into the dynamic behaviour of specific components of the bridge. Further, this information was used later by the bridge owner to evaluate the bridge's expected response during an earthquake. Key words: steel bridges, dynamic response, full-scale tests.
Nonparametric modeling of mass transfer coefficients for air stripping packed towers
Authors: Narbaitz Roberto M. , Djebbar Yassine
Published: January 2010

Existing parametric correlations have been found to have difficulties in predicting the removal of trace levels of volatile organic chemicals by modern air stripping towers. In this study, a new approach using a nonparametric kernel regression method was used to predict the mass transfer coefficient, KLa, of air stripping towers. Although only four variables were used, the predictions are already improved more than 50% as compared with Onda correlation, the best existing parametric correlation. The proposed technique shows a dependency of KLa on the liquid flow rate which is in good agreement with established theory. Previous parametric approaches were unable to model this relationship correctly. Key words: mass transfer coefficient, air stripping tower, volatile organic compound, nonparametric kernel regression.
Behaviour of single and double 102 mm split ring conneotions loaded in tension
Authors: Quenneville J. H. P. , Charron J. G. A.
Published: January 2010

Two experimental studies were undertaken to verify the effect of the end distance on the resistance of single connector joints using 102 mm split rings and the combined effects of timber connector end distance and spacing on the resistance of double connector joints using 102 mm split rings. A total of 108 test specimens were loaded to failure in tension. Sixty of those tests were single connector joints with end distances varying from 80 to 270 mm. The remaining 48 test specimens were double connector joints with split ring end distances varying from 100 to 270 mm and a spacing of either 125 or 230 mm. The single connector joints results showed an increase in connector resistance with the increasing end distance. However, it was shown that even though some specimens were tested at an end distance below the standard minimum required value (end distance of 80 mm instead of the minimum required of 135 mm), they resisted a significant load. For the double connector joints, it was observed that brittle failures are more common, as opposed to single connector joints which tend to fail showing signs of ductility. Also, results showed that the connection resistance is not a direct function of the number of fasteners and that a factor of 0.475 has to be applied. Results obtained suggested that the end distance does not have a statistically significant influence on the resistance of connections with connector spacing at either 230 or 125 mm. However, the spacing of the connectors appears to affect the resistance. Thus, the design philosophy of Clause 10.3.3 of the wood design standard is inadequate for these particular joints. Recommendations to determine connection resistances are provided. Key words: wood, fasteners, resistance, split ring, end distance, spacing.
Damage to water distribution system caused by the 1995 Hyogo-ken Nanbu earthquake
Authors: Kuraoka S. , Rainer J. H.
Published: January 2010

The Hyogo-ken Nanbu earthquake on January 17, 1995, inflicted severe damage to the water distribution system, not only disrupting daily life activities and industrial operations but also causing major problems in fighting fires which destroyed 7377 homes. Disruption of water service is largely due to abundant water main breaks rather than failures of treatment plants, pumping stations, or the reservoirs. The total number (3300) of pipe breaks of the seven cities within 40 km east of the epicentre is one of the largest recorded among the strong earthquakes that occurred in the past 20 years. The major damage that led to the lack of water in Kobe City is described, and damage trends of water mains are compared with those found in past earthquakes. Important factors identified from these trends are noted for the study of estimation and mitigation methods of water main damage for the Greater Vancouver area. Key words: earthquake, Hyogo-ken Nanbu, water mains, transmission line, reservoirs, fires, restoration.
Performance of steel bridges during the 1995 Hyogo-ken Nanbu (Kobe, Japan) earthquake
Authors: Bruneau Michel , Wilson John C. , Tremblay Robert
Published: January 2010

A large number of steel bridges were damaged by the January 17, 1995, Hyogo-ken Nanbu (Kobe, Japan) earthquake. The concentration of steel bridges in the area of severe shaking was considerably larger than for any previous earthquake this century. As a result, this earthquake has provided a unique opportunity to examine how steel bridges of various designs and configurations behave when subjected to severe ground shaking. In this paper, a description of the Japanese past and current bridge design requirements is first presented, followed by an in-depth overview of the observed damage to steel bridges. The relevance of these observations to the Canadian bridge design practice is also reviewed. Key words: earthquake, seismic, steel, bridges, steel columns, buckling, brittle fractures, bearing failures, seismic restrainers, design codes.
Damage to concrete structures due to the January 17, 1995, Hyogo-ken Nanbu (Kobe) earthquake
Authors: Mitchell Denis , DeVall Ronald H. , Kobayashi Katsumi , Tinawi René , Tso W. K.
Published: January 2010

A brief history of the detailing changes following different Japanese earthquakes is presented. The design steps for reinforced concrete structures, as prescribed in the 1981 Japanese building code, are described. Observations on the damage and the collapse of reinforced concrete structures caused by the 1995 Hyogo-ken Nanbu earthquake are reported. Failures occurred in older structures built before the improved 1981 code. Deficiencies observed include discontinuities due to the change between composite steel and reinforced concrete construction and reinforced concrete construction in columns, poor detailing of transverse reinforcement in columns, lack of transverse reinforcement in beam–column joints, insufficient amount of vertical and horizontal reinforcement in walls, presence of significant torsional eccentricities, abrupt changes in stiffness over the height of buildings, and the use of "short" columns or "short" beams exhibiting high shear-to-moment ratios. The excellent performance of structures designed using the 1981 Japanese code is described. Key words: earthquake, Kobe, concrete structures, codes, damage, design.
The Hyogo-ken Nanbu (Kobe) earthquake of 17 January 1995: seismological aspects and ground motions
Authors: Byrne Peter M. , Finn W. D. Liam , Ventura Carlos E.
Published: January 2010

The strong ground motions of the Kobe earthquake are examined together with the reasons for the catastrophic damage. Soil effects – amplification and liquefaction – are shown to be important. Implications for western Canada are discussed. Key words: seismicity, ground motions, amplification, liquefaction, damage.
Damage to masonry buildings caused by the 1995 Hyogo-ken Nanbu (Kobe, Japan) earthquake
Authors: Bruneau Michel , Yoshimura Koji
Published: January 2010

The seismic performance of the few masonry structures present in the Kobe area and subjected to the severe Hyogo-ken Nanbu earthquake is a minor concern when compared to the overwhelming damage suffered by other types of structures. However, in order to dispel the myth that masonry structures are nonexistent in Japan as well as a few other misconceptions, and for the sake of completeness within the concerted multipaper reporting effort on the Hyogo-ken Nanbu (Kobe) earthquake by the Canadian reconnaissance team which visited the epicentral area of this earthquake, a brief description of the past and present state of masonry construction in Japan is first presented, followed by a short description of the damage to unreinforced masonry buildings, masonry garden-walls, and nonstructural masonry elements, as observed by the authors during their visits to the Kobe area. Key words: earthquake, seismic, masonry, buildings, bearing walls, unreinforced masonry, reinforced masonry, failures, design codes.
Simulations expérimentale et numérique de la dispersion hydrodynamique d'un effluent pollué en milieu côtier estuarien
Authors: Gidas Nicolas K. , Koutitonsky Vladimir G.
Published: January 2010

An experimental and numerical study was performed to measure and simulate the hydrodynamic dispersion of a pollutant effluent discharged by an outfall diffuser into an estuarine coastal zone near Rimouski, Canada. Field measurements of currents, tides, salinity, and winds were obtained in the vicinity of the injection site, and two tracer dispersion experiments were carried on in these coastal waters. The measurements were taken before and after the construction of the marine outfall diffuser. The similitude between the plume of a tracer (physical model) released into the coastal waters before construction and that of the real effluent (prototype) discharged at the same site was studied. A new coefficient of similitude was established, which allows to transpose the concentrations of the physical model tracer to the waste water concentrations of the prototype. The numerical simulation (2D) is performed with a hydrodynamic model and an advection–dispersion model of the MIKE21 system from the Danish Hydraulic Institute, using the so-called telescopic approach. The objective of these simulations was to predict, among other things, the pollutant effluent concentrations for critical hydrodynamic conditions relative to the aquatic ecosystem to be protected. The methodology elaborated was used for the management of the coastal environments subjected to pollution. Key words: simulation, hydrodynamics, advection–dispersion, numerical model, similitude, tide, effluent.
A comparison of the gust factor method and the patch load method of analysis of guyed towers
Authors: Selby Robert G. , Dryburgh Robert B.
Published: January 2010

The Canadian standard CAN/CSA-S37-94 "Antennas, towers and antenna supporting structures" (S37) has introduced as an appendix a quasi-dynamic method of analysis. This patch load method yields a more realistic pattern of forces in a guyed tower, but S37 contains no firm guidelines as to when this new method is required over the conventional static gust factor approach. This paper describes various comparative studies that were made to determine the conditions under which the normally used gust factor approach does not give sufficiently acceptable results so that patch load analyses are required. Results of the parametric studies and the analyses of a large number of actual towers showed that leg loads in the upper few spans tended to be about 15% larger on average in a patch load analysis. Face shears at the guy supports were also about 15% higher on average in the patch load method. The studies revealed no strong trends between the patch load and gust factor correlation and the tower parameters, although there were slight trends suggesting that a patch load analysis was warranted if the tower height was greater than 250 m, the aspect ratio was greater than 120, or the drag area exceeded 2.0 m2/m. The presence of a cantilever accentuated the margin between the results of the two methods. Key words: guyed towers, analysis, wind loading, dynamic effects, patch load, gust factor.
Best subset modelling of phosphorus in the Grand River using correlated variables
Authors: Tyagi A. , Sharma M. , McBean E.
Published: January 2010

Statistical models are developed for the estimation of phosphorus concentrations for different seasons and locations using routinely monitored water quality parameters in the Grand River Basin. Two methods of modelling, namely the best subset model and the stepwise regression method based on R2 and F values, are described. The best subset modelling procedure enables comparison between full model (containing all the independent variables) and subset models (containing subsets of independent variables). For correlated independent variables, the best subset modelling procedure is shown to provide a better model than the stepwise regression procedure. The statistical modelling results indicate that suspended solids play an important role in the prediction of phosphorus levels and consequently decreasing suspended solids would decrease the growth of aquatic plants in the Grand River Basin. Key words: regression modelling, water quality, phosphorus, suspended solids, rivers, statistics.
An investigation of hoist-induced dynamic loads on bridge crane structures
Authors: Barrett D. A. , Hrudey T. M.
Published: January 2010

A series of tests were performed on a bridge crane to investigate how the peak dynamic response during hoisting is affected by the stiffness of the crane structure, the inertial properties of the crane structure, the stiffness of the cable-sling system, the payload mass, and the initial conditions for the hoisting operation. These factors were varied in the test program and time histories were obtained for displacements, accelerations, cable tension, bridge bending moment, and end truck wheel reactions. Values for the dynamic ratio, defined as peak dynamic value over corresponding static value, are presented for displacements, bridge bending moment, and end truck wheel reactions. A two degree of freedom analytical model is presented, and theoretical values for the dynamic ratio are calculated as a function of three dimensionless parameters that characterize the crane and payload system. The predicted dynamic ratios are found to be conservative when compared with the test results. A general format is suggested for dynamic factors in design standards that apply to bridge cranes with constant speed motors. Key words: bridge crane, hoist, dynamic load.
Effets des cendres volantes sur le développement des résistances mécaniques des bétons préfabriqués
Authors: Maltais Y. , Marchand J. , Gagné R. , Tagnit-Hamou A.
Published: January 2010

The results of an investigation of the influence of fly ashes on the development of mechanical properties of concretes subjected to 24-h thermal curing are presented in this paper. In addition to the curing temperature (23 and 60 °C), the variables studied in this investigation were the type of cement (types 10 and 30) and the source of fly ashes (four different North-American class F fly ashes). Overall, 10 different concrete mixtures were tested. Test results indicate that thermal curing tends to increase significantly the concrete compressive strength in the first 24 h. Data also demonstrate that the thermal curing regime does not have any detrimental effect on the long-term compressive strength of ordinary portland cement concrete. Compressive strength of fly ash concretes was significantly reduced by thermal curing in the 1- to 28-day period, despite an initial increase. The influence of thermal curing on the development of concrete compressive strength is discussed. Key words: compressive strength, steam curing, fly ashes, precast concrete.
Structural dynamic properties of a reinforced concrete high-rise building during construction
Authors: Ventura Carlos E. , Schuster Norman D.
Published: January 2010

This paper presents the results of a study on the variability of the dynamic properties of an irregular high-rise building during its construction. Most of the knowledge about structural dynamics of high-rise reinforced concrete buildings is based on uniform structures. Hence, there is concern about extrapolating this knowledge to the behaviour of nonuniform building that emerge from current architectural trends. A clear example of these trends is the building selected for this study. This 30-storey reinforced concrete building is representative of the type of current construction in Vancouver, British Columbia. The lateral force resisting system in this structure is uniform in plan and elevation, while the distribution of storey mass is asymmetrical owing to its geometry as well as a major setback at one corner. Dynamic characteristics were determined by analyzing ambient vibrations of the structure. The objectives of this study included determining natural frequencies and corresponding mode shapes, determining the effect of architectural components, assessing base motion, and assessing the manner of the core's deformation. In addition, a three-dimensional dynamic analysis was performed to assess the accuracy of modeling techniques. Finally, base shears and overturning moments during different stages of construction were assessed in accordance with current building codes. Key words: structural dynamics, ambient vibration measurements, earthquakes, building construction, mode shapes and frequencies.