bluuebunny/crossref_metadata_2025 huggingface dataset:
An analysis of the performance of welded wide flange columns
Authors: Chernenko Diana E. , Kennedy D. J. Laurie
Published: January 2010

The Canadian Standards Association Standard CAN-CSA-S16.1-M89 “Limit states design of steel structures” assigns welded wide flange (WWF) columns to the column curve for rolled H-shaped sections. This is conservative because of differences in the production of WWF and rolled sections. The WWFs are stipulated to have flame-cut edges. The residual stress pattern, with favourable tensile stresses, results in a delayed loss of stiffness as weak axis inelastic buckling occurs. Thus the weak axis and strong axis buckling curves lie closer together for WWF shapes than they do for rolled H-shapes. Automatic cutting and welding processes result in close tolerances on out-of-straightness. As well, the statistical variations in the geometric properties are favourable. A detailed analysis of data collected from mill records and on-site measurements was made to obtain statistical parameters of relevant geometric and material properties. A finite element program modelling inelastic behaviour, residual strain patterns, out-of-straightness, and material properties was used with the test results of others to establish test-to-predicted ratios of column strengths. Parametric studies provided an assessment of the effect of varying residual strain patterns and column out-of-straightness. This formed the basis for determining the factored compressive resistance of WWF sections for three different slenderness ratios. Key words: columns, inelastic analysis, out-of-straightness, residual stresses, welded wide flange.
Etude de la résistance au gel de bétons contenant un fluidifiant
Authors: Pigeon Michel , Langlois Marcel
Published: January 2010

There is some controversy about freezing resistance of concrete containing superplasticizers. It has been quite convincingly demonstrated that, in some cases, such admixtures can significantly alter air-void systems in concrete. Some researchers believe, however, that concrete with superplasticizers can resist frost even when the air-void spacing factor is higher than the usual limit of 200 μm. The freeze–thaw cycle resistance tests described in this paper show that with the two types of concrete tested (a plain concrete with a water/cement ratio of 0.50 and a concrete with the same water/cement ratio but containing silica fume), the critical air-void spacing factor value is not significantly affected by the presence of a superplasticizer. When regular concrete is to be exposed to freeze–thaw conditions, the air-void system should meet the usual standards even when a superplasticizer is present. Key words: concrete, freezing and thawing, durability, superplasticizer, spacing factor, silica fume, water–cement ratio. [Journal translation]
Application of nonparametric regression to groundwater level prediction
Authors: Adamowski Kaz , Feluch W.
Published: January 2010

A new nonparametric regression model is proposed to investigate the relationship between groundwater level fluctuations and streamflow time series observations. The developed nonparametric model does not force the relationship between variables into a rigidly defined class (i.e., linear regression) and is capable of inferring complicated relationships. The results from the analysis indicate that the nonparametric method gives more accurate prediction results than those obtained from parametric regression. A split-sample experiment shows that nonparametric regression gives accurate prediction (extrapolation) results at the validation stage. Key words: nonparametric regression, cross-validation method, groundwater level, streamflow.
Updating hydrological model forecasts
Authors: Assaf Hamed , Quick Michael C.
Published: January 2010

A flow updating model is presented in which the flow is estimated using outputs from a physically based watershed model (UBC watershed model) and a feedback of the most recent flow measurement. These outputs (the flow components) are modified by certain parameters that are updated whenever a flow measurement is available. The updating process is based on a state-space model where Kalman filter technique is used to update the parameters from their past values and the most recent flow measurement. The extent of updating is controlled by the relative uncertainties in the flow measurements and the parameters. The updating model has been applied on the Illecilewaet basin and the flow forecasts have shown great improvement over the ones obtained by using the UBC watershed model only. The flow updating model is formulated based on an assumption that the errors in the watershed model output are of a certain linear structure. The validity of such assumption could be tested by comparing some statistical measures of performance. Key words: real-time, flow forecasting, updating, Kalman filter, state-space, linear errors.
Modelling the steady-state circulation in a distorted physical model of the Windermere Basin
Authors: Blaisdell M. A. , Tsanis I. K. , Krestenitis Y.
Published: January 2010

Two depth-averaged circulation models were applied to a distorted physical model of the Windermere Basin of Hamilton Harbour. One of the models, which includes the nonlinear advective terms, was successful in reproducing the hydraulically induced steady-state circulation. Using a Lagrangian model and the above circulation, trajectories observed in the physical model were replicated. Model sensitivity to changes in the bottom friction and horizontal diffusion of momentum were studied. An increase in each was found to decrease the size of zones of recirculation. Key words: distorted physical model, circulation model, bottom friction, horizontal diffusion.
An expert system for predicting the cost – time profiles of building activities
Authors: Christian John , Kallouris George
Published: January 2010

This paper describes the development of a prototype knowledged-based expert system for predicting the cost – time profiles of various construction activities in New Brunswick. Knowledge, both quantitative and qualitative, about the cost – time patterns of various activities in educational, office, and apartment building projects in New Brunswick are stored in an expert system shell (Personal Consultant Plus). The system simulates a consultation between an expert and a user, where the microcomputer represents the expert and the user is the prospective building contractor or owner. The output of the consultation shows how the total cost of the various trades will most likely be distributed over time. This will enable the contractor and the client to anticipate the probable financial commitments each month, even before any schedule is available, once an investment decision has been made. Funds can then be arranged in such a way as to match the progress of work and therefore meet the financial demands of each individual building activity. Key words: cost – time profiles prediction, expert system, shell, knowledge base, buildings, construction, rules, parameters.
Earthquake resistant design of concentrically braced steel frames
Authors: Redwood R. G. , Channagiri V. S.
Published: January 2010

New provisions of the CSA standard for steel structures (CAN/CSA-S16.1-M89) dealing with detailing of concentrically braced frames for seismic design are described and related to requirements of the National Building Code of Canada. The basis of the new requirements is outlined, and an example eight-storey frame is used to outline a methodology for the design process for a ductile braced frame and to illustrate the impact of the provisions. Key words: design, structural engineering, steel, earthquakes, braced frame, standards.
Earthquake-induced sloshing in a rigid circular tank
Authors: Isaacson Michael , Subbiah Kesavan
Published: January 2010

The present paper describes the sloshing of a liquid in a rigid circular cylindrical tank subjected both to harmonic and to irregular base motion. Initially, the boundary value problem for the case of an inviscid fluid and a harmonic base motion is solved on the basis of linearized potential flow theory. The case of energy dissipation of a real fluid is then treated by a simple extension to this, which involves an assumption of dissipation at the free surface and a corresponding modification to the free surface boundary condition. In order to treat earthquake-induced motions, this solution is then extended to (i) the stochastic response to a base motion which describes a stationary random process; (ii) the time-domain response to a specified base acceleration record; and (iii) a simplified method of estimating maximum forces using a modal analysis and involving earthquake response spectra. The estimation of hydrodynamic damping is briefly considered, and example applications are provided. Key words: added mass, cylinders, damping, earthquakes, hydrodynamics, sloshing.
Modelling chlorinated discharges from water treatment plants: a case study
Authors: Stanley S. J. , Smith D. W.
Published: January 2010

Virtually all water treatment plants have the ability to discharge chlorinated water back to the source stream. Such water may originate from an emergency bypass, filter backwash water or other diversions. The discharge of chlorinated water to receiving water bodies has caused concern because of its toxicity effects to aquatic biota and potential health hazards. This paper demonstrates the use of a transverse mixing model that incorporates both mixing and pollutant decay in assessing the environmental impact of these discharges. The results of such an analysis can be used to base control measures on, such that environmental impact is minimized and guidelines met. Presented is an impact assessment of chlorinated wastewater discharges from two water treatment plants in Edmonton, Alberta. Key words: environmental impacts, mixing, stream pollution, chlorine decay, water treatment.
Comportement d'un cadre rempli soumis à un chargement cyclique: modélisation pour une analyse dynamique non linéaire
Authors: El-Ouali Taoufik , Houde Jules , Tinawi René
Published: January 2010

This paper presents the results of an experimental program investigating the behavior of a steel frame with masonry infill panels subjected to cyclic loadings. Three types of masonry frequently used were tested. Loads were high enough to crack the infill panels without yielding the steel frame. The effects of the infill panels on the stiffness and the energy dissipation of the structure were evaluated. From the experimental results obtained on the three types of masonry, models are proposed to evaluate the behavior of a structure with infill panels. These models could be used in nonlinear dynamic analysis. Key words: masonry infills, masonry, seismic behavior, cyclic loading, modelling, frames.
Wind-wave-induced suspension of mine tailings in disposal ponds – a case study
Authors: Lawrence G. A. , Ward P. R. B. , MacKinnon M. D.
Published: January 2010

Linear wave theory and wave hindcasting are applied to derive an expression for the depth of water needed to prevent the wind-wave-induced suspension of sediments in mine tailings ponds. The depth is expressed as a function of four factors: the threshold velocity, the wind velocity, the fetch over which the wind blows, and a factor based on the statistical distribution of wave heights. This study was motivated by the need to determine the thickness of water required to prevent the suspension of sludge solids in existing and proposed tailings ponds at Syncrude Canada Ltd.'s oil sands plant. Although data relevant to this problem are used to provide a specific example, the results are applicable whenever sediment suspension is caused by fetch-limited, deep water, wind waves. The results should be of particular use when the available data set is limited, e.g., for proposed tailings ponds. Key words: linear wave theory, wave hindcasting, wind-wave-induced suspension, threshold velocity, sludge capping, reclamation ponds, mine tailings ponds.
Ice jam flood forecasting: Hay River, N.W.T.
Authors: Stanley S. J. , Gerard R.
Published: January 2010

Much of the town of Hay River, N.W.T., is located on the low-lying land of the Hay River delta, and is subject to severe ice jam floods every decade or so. As a first line of defence against these floods, it was proposed that an ice jam flood forecast procedure be developed. The major components of the study included a review of historical flood data, resident interviews, field surveys, and observations of the delta ice regime. It was found that a 1–2 day forecast of discharge in Hay River can be directly determined from discharges measured at a Water Survey of Canada gauging station upstream. From this and from an understanding of the breakup ice regime developed from the study as well as the water level–discharge relations determined for ice jams at three locations in the delta, it was possible to develop a first-generation ice jam flood forecasting procedure that gave a 1–2 day warning of high water at each of the three locations. The procedure was evaluated against the breakup events of 1988 and 1989 with reasonable success. The development and application of this procedure is described in the paper. Key words: rivers, floods, ice jams, forecasting.
Étude de la remontée relative des niveaux d'eau de l'estuaire du Saint-Laurent
Authors: Anctil François , Troude Jean-Pierre
Published: January 2010

Data available on water levels in the St. Lawrence Estuary were used to evaluate the relative variation of mean water levels in this area. Only measurements taken at Pointe-au-Père could be used to evaluate this parameter with the required precision; a relative stability of water levels (−0.3 ± 0.5 mm/year) was observed. Upstream stations, especially the ones in the estuary, are highly influenced by the freshwater input of the St. Lawrence River. The high discharge of the river has been identified as the main cause of high water levels observed between 1970 and 1988 and, consequently, of bank erosion at the limit of the St. Lawrence estuary. Key words: discharge, erosion, estuary, mean water level, relative variation.
Behaviour of transversely loaded continuous steel–concrete composite plates: experimental program and test results
Authors: Kennedy Stephen J. , Cheng J. J. Roger
Published: January 2010

It is apparent from a review of the literature and current research related to the design of ice-resisting walls for offshore structures that there is a need for more efficient designs of these structural elements. The object of this study was to examine an alternate structural element for ice-resisting walls, a flexible composite plate system, which is simple in detail, design, and construction and utilizes the capacity of the section.An exploratory experimental program was undertaken to determine the strength and behaviour of flexible steel–concrete composite sandwich plates, without mechanical shear interconnectors, subject to transverse loads. A series of six composite plate elements, continuous over supporting composite bulkheads and axially restrained, were tested with a four-point load system. The primary variables investigated were plate thickness, which varied from 3.18 to 6.35 mm, and section depth which gave span-to-depth ratios from 15 to 25.Three regions of behaviour of the composite plates were observed: flexural, flexural membrane, and membrane. The flexural capacity is limited by the development of a plastic mechanism, and the ultimate capacity is limited by the tensile–shear strength of the double membrane steel plates. The average maximum centre-span deflection at failure exceeded one-sixth of the span. The characteristics of the flexible composite plates make it a favourable alternative to conventional and semi-rigid composite plate construction. Key words: composite, concrete, ductility, energy absorption, flexible, flexural behaviour, membrane behaviour, plates, steel.
A bridge design and evaluation method derived from weigh-in-motion data
Authors: Heywood Robert J. , O'Connor Colin
Published: January 2010

Weigh-in-motion data collected in Australia and Canada have been analysed to obtain the distributions of midspan moment in simply supported beams with spans between 10 and 40 m. These moments are used to demonstrate the concept of a bridge site index. This concept enables moments for a particular recurrence interval to be predicted with reasonable accuracy from a single number, the bridge site index. A relationship is developed between this bridge site index and the Ontario legal limits which are based on the Ontario equivalent base length concept. Applications such as data summary, site ranking, bridge evaluation, fatigue, and bridge management are discussed. Key words: bridges, live loading, weigh-in-motion data, design loads, bridge management.
Spray overtopping rates for Tarsiut Island: model and field study results
Authors: Muzik I. , Kirby A.
Published: January 2010

This paper describes a 1:30 three-dimensional Froude scaled model study undertaken to determine the spray overtopping volumes that would result from storms on Tarsiut Island. During the open water season of 1982, spray overtopping data were collected on Tarsiut Island and then compared with the model study results. The Tarsiut field data when compared with the model data were lower by a factor of 3. Some possible reasons for this are scaling errors, physical differences between the model and the prototype, and the model wind speed. The model wind speed used was roughly 3.75 times the Froude scaled wind speed and the literature suggests that a wind speed of twice the Froude scaled wind speed would produce overtopping volumes closer to the field data. The spray overtopping rates landward from the caisson face reduced in an exponential manner, which was substantiated by the literature. Spray overtopping for both the model study and Tarsiut Island was initiated at approximately the same significant wave height. Key words: spray intensity, wave height, model study, field program, artificial island, wind speed.
Simplified methods of bridge analysis for the third edition of OHBDC
Authors: Bakht Baidar , Jaeger Leslie G.
Published: January 2010

Research conducted since the publication of the second edition of the Ontario Highway Bridge Design Code (OHBDC) in 1983 has paved the way for further simplification of the simplified methods of bridge analysis specified by the code. The third edition of the OHBDC (1991) incorporates simplified methods, most of which have been made even more "user friendly" in the light of this research. This paper gives the details of these new methods of analysis along with their developmental background. It is shown that the low volume of traffic on bridges on lightly travelled roads can be accounted for conveniently through the simplified methods of analysis by incorporating in them the lower values of the modification factors for multipresence of vehicles specified in the OHBDC (1991). The paper also discusses those major pieces of contemporary research work in load distribution analysis, the end product of which was considered but could not be utilized in the OHBDC. Key words: analysis, bridge, load distribution, multi-beam bridges, multipresence of vehicles, slab-on-girder bridges, timber bridges.
Field studies of fishways in Alberta
Authors: Rajaratnam N. , Katopodis C. , Paccagnan R.
Published: January 2010

This paper presents a detailed account of field studies performed on one pool-weir and several Denil and vertical slot fishways in the province of Alberta. The pictures show the broad features of the flow. The velocity profiles obtained in the field studies have confirmed the measurements made in the laboratory on scale models and have enhanced the general picture, particularly for the vertical slot fishways. This paper provides hydraulic engineers with information for understanding the primary hydraulic characteristics of fishways. Key words: fishways, field studies, hydraulics, open-channel flow, turbulent flow.
Prediction of external wave pressures on a rubble mound breakwater
Authors: Williamson Derek C. , Hall Kevin R.
Published: January 2010

The external pressures on the front face of a rubble mound breakwater resulting from wave attack are examined in this paper. This is done through extensive model tests employing regular waves up to 30 cm in height, on a conventionally designed breakwater with front slopes of 1:1.5, 1:2, and 1:3. The measured pressures are examined based on their relationship to a number of different parameters, including wave steepness, wave height, wave period, breakwater front slope, core permeability, and elevation on the breakwater relative to the still water level. The average differential pressure, the maximum recorded differential pressure, the average minimum pressure, and the pressure rise and fall times are investigated, producing a regression equation for each case based on a number of independent variables. The regression equations demonstrate the great effect of the elevation on the breakwater, and often wave steepness; the much lesser effect attributed to the breakwater front slope; and the minimal effect that the core permeability has on most of the components describing the external pressures measured on a breakwater under wave attack. Key words: breakwater, rubble, pressure, external, prediction.
Potential leachate production due to cold weather effects
Authors: Leskiw E. J. , Sego D. C. , Smith D. W.
Published: January 2010

The effect of a temperature gradient on the process of moisture movement within the landfill environment has not been studied in cold-climatic regions. A laboratory study investigating the migration and accumulation of moisture within shredded municipal refuse subjected to a temperature gradient is reported. The laboratory study consisted of four series of experiments involving three samples in each series. The measured parameters included water intake rate from a free water source, final moisture content profiles, and temperature gradient. In each series of experiments, water intake to the sample was attributed to the freezing process. The parameter which characterizes the relationships between the measured water intake rate and temperature gradient is the segregation potential. The results of the tests showed that moisture migrates through the freezing refuse to form ice lenses. The significance of this moisture movement during the cold weather is the increase in the leachate production which may occur within the landfill. Because of scale-up complexities, field investigations are necessary to verify the laboratory observed findings. Key words: leachate production, sanitary landfill, refuse, freezing, frost heave.
Temporal characterization of municipal solid waste leachate
Authors: Reitzel Steve , Faquhar Grahame , McBean Edward
Published: January 2010

Estimates of leachate strength and its variance over time are examined to provide a management tool for forecasting the need for leachate treatment and groundwater monitoring during the active phase of landfilling. Using historical lysimeter studies, regression curves are developed characterizing leachate strength for a series of contaminants, namely, chloride, chemical oxygen demand, total phosphates, ammonia, iron, cadmium, and lead. For each of these contaminants, the time-scale for the regression curves is normalized with regard to moisture addition and refuse mass, and is presented as cumulative litres of leachate per kilogram of municipal solid wastes. Key words: leachate, leachate quality, landfill, statistical analyses, solid wastes.
Modelling of hollow structural section trusses
Authors: Frater George S. , Packer Jeffrey A.
Published: January 2010

It has been recently advocated that a practical static design of hollow structural section (HSS) Warren and Pratt trusses, having either gapped or overlapped connections, can be performed on the basis of a force distribution obtained from an elastic analysis of the truss with either all the members pin-jointed or the web members pin-jointed to continuous chord members. However, at the service load level, gap-connected truss deflections have been previously underestimated by around 12%–15%. Laboratory testing of HSS trusses has accordingly been undertaken to establish experimental axial force and bending moment distributions and truss deflection patterns. Tests have been conducted on two large-scale, 12.0 and 12.2 m span, simply supported, HSS Warren trusses, comprised of 60° gap or overlap K-connections. Based upon the experimental behaviour of the two trusses and the theoretical analyses, it is shown that simple pin-jointed analysis is sufficient to give good predictions for web and chord member forces. In the case of truss deflections, the contribution of connection flexibility on truss deflection has been taken into account using a simple virtual work method, and excellent agreement is then obtained between the predicted and actual truss deflections. Key words: steel structures, hollow structural sections, trusses, connections, deflections.
Slip modulus in bolted timber joints
Authors: Dyer D. B. Van
Published: January 2010

This paper is concerned with the initial load–slip behaviour of laterally loaded bolted timber joints and deals specifically with verifying a theory for determining the values of slip modulus in mechanically fastened timber joints. Such a theory is essential in dealing with the phenomenon of interlayer slip, which occurs in built-up timber columns with nonrigid joints. The concept of a beam on an elastic foundation is used to evaluate the slip modulus. The theoretical predictions are compared with the test results of 75 timber joints. Good agreement is observed between the experiment and the theory. Key words: timber joints, bolts, nails, wood, interlayer slip, slip modulus, built-up wood columns, shear, lateral loads.
Canadian highway bridge evaluation: derivation of Clause 12 of CAN/CSA-S6-88
Authors: Bartlett F. Michael , Buckland Peter G. , Kennedy D. J. Laurie
Published: January 2010

Improvements to Clause 12 of CAN/CSA Standard S6-88 "Design of highway bridges" required the transformation of basic findings into a form suitable for use by evaluators. The number of dead load categories was reduced, and the rating equation was simplified. Rating factors calculated using the new criteria were checked against past practice. Practical guidelines for material grade identification and the evaluation of deteriorated components were developed. Three examples of the application of the provisions are included. Key words: calibration, codes (standards), evaluation, highway bridges, load and resistance factors, mean load method, safety.
Étude en laboratoire de l'adhérence béton de resurfaçage - dalle de chaussée
Authors: Do Minh-Tan , Chanvillard Gilles , Lupien Claude , Aïtcin Pierre-Claude
Published: January 2010

This paper presents a laboratory study on the bonding of a concrete overlay to an old slab. The main variables of the study were the bonding agents and the initial slab temperature when the overlay was placed. A flexure test setup, based on the theory of beams of elastic foundation, was developed. The results obtained were compared with those of the slant–shear test. Key words: bonding agent, debonding, elastic foundation, interface, beam.
Regression-based urban arterial road delay models
Authors: Helali K. N. , Khan A. M.
Published: January 2010

During the last two decades, emphasis in transportation planning has shifted from long-term capital-intensive construction projects to short- and medium-term, relatively low capital cost, projects aimed at using existing transportation facilities more efficiently. This shift caused the integration of transportation system management (TSM) activities into the overall transportation planning process. Presently, the TSM endeavours are regarded as a prerequisite prior to initiating major capacity expansion type of capital works.Although the TSM initiatives are undertaken in response to congestion (delay), energy, environment, and safety concerns, reducing delay is a key measure of effectiveness. Despite the importance of this factor, there is a lack of efficient tools that are capable of estimating delay corresponding to TSM endeavours. Most, if not all, of the existing delay models have been developed for detailed operational analysis. These models are data-intensive and require highly specialized human and machine types of resources.In this research, multi-link streets and networks were synthesized and their performance in delay terms was estimated through the use of a microscopic simulation program, NETSIM. The output of NETSIM, in conjunction with physical and traffic characteristics of networks, were used to develop the multiple regression type of macro-simulation models of delay. The regression models developed are capable of estimating vehicle delay for urban streets. Field data collected by using the videotape technology and maps were utilized to validate the models. Key words: delay, model, simulation, traffic, transportation, urban.
Single-station estimates of suspended sediment loads using sediment rating curves
Authors: Hansen David , Bray Dale I.
Published: January 2010

Sediment rating curves in conjunction with daily flow data have often been used to estimate the total mass of sediment flowing past a given river cross section over relatively long periods of time. Techniques are presented that seek to make the best use of limited noncontinuous suspended sediment concentration data to generate nine partial years of suspended sediment load by means of sediment rating curves for the Kennebecasis River, N.B. (drainage area of 1100 km2). Initially, the data were partitioned in an attempt to improve correlations between concentration and discharge. Such partitioning by season, month, periods of rising stage, and periods of falling stage did not uniformly improve correlations as compared with the correlations for nonpartitioned data. Various combinations of less well-known methods were then used, including a moving intercept method that makes greater use of point concentration observations in time, and correction factor methods for simple power-type relations as suggested by Ferguson and by Duan. In addition, the validity of some of the underlying assumptions for performing ordinary least-squares regression is examined for this data set. Finally, the effect of daily flow averaging on the computed load was examined and found to be small for this basin. Key words: suspended sediment, C–Q rating curves, flow averaging, washload estimates, statistical bias, regression estimates.
Factors influencing formwork productivity
Authors: Smith Gary R. , Hanna Awad S.
Published: January 2010

Estimates indicate that 30 to 70 percent of cast-in-place concrete cost is attributable to the assembly and stripping of formwork. This wide percentage range is partially due to factors that are not well understood with regard to their influence on productivity. The purpose of this paper is to identify the factors that influence formwork productivity and identify a methodology to evaluate productivity data. Two groups of factors were found to have a great effect on formwork productivity: non-measurable factors such as contract document and measurable factors such as engineering design. This paper discusses the effect of both groups of factors on the productivity of vertical formwork. To quantify the effect of the measurable factors on formwork productivity, a case study of the productivity of a crew of carpenters erecting wall formwork for a three-story underground parking structure is presented and analyzed. Data were collected by physically measuring the daily output of vertical formwork erected and the total daily work hours. Key words: formwork, productivity, construction methods.
An interactive program for the limit states design of wood
Authors: Neis M. E. , Neis V. V.
Published: January 2010

A microcomputer program called Timber LSD-Design was written using an OOP (object-oriented programming) application to assist structural engineers in the design of wood structures. The program creates a number of objects (fields, buttons, pull-down menus, graphics, and "hot" text) on the computer screen that respond with dialog boxes, calculations, and navigational aids when the user selects them. The program provides the user with information about member and fastener design, specified wood strengths, and modification factors and it graphically illustrates typical problems encountered in the limit states design of wood. Key words: wood design, limit states design, object-oriented programming, interactive computing, microcomputers.
Optimum design of frames under alternate loading condition
Authors: Al-Salloum Yousef A. , Siddiqi Ghulam Husain
Published: January 2010

A generalized formulation of a procedure for optimum design of linear elastic plane frames under alternate loading condition is presented. The condition of alternate loading is employed to ensure that the optimum design, under individual application of envisaged load events, does not violate the limit state requirements on strength. The behavioral constraints both on strength and on displacement, including those of the axial load – moment interaction prescribed in code specifications, and the side constraints on member sizes are incorporated in the formulation. The method permits grouping of members to effect repetition and uniformity of member sizes, to a desired extent, throughout the structure. A predictor–corrector scheme is employed to arrive at the optimum design. The predicted design vector is expressed in terms of true member forces by an implicit scheme. In the correction phase, dynamic scaling and a unique process of step-size reduction are employed on the predicted design vector in the fully stressed design iteration to avoid bypassing an optimum during the search procedure. An algorithm for implementation of the proposed optimal design procedure is presented. The limit state design procedure of the Canadian Standard S16.1-M89, for members subjected to combined axial and bending action, is embedded in the algorithm. The algorithm is illustrated with an example problem and verified with results available in the literature. Key words: frames, optimum design, alternate loading, fully stressed, optimization, limit state.
Coliform inactivation in sludge by copper sulphate
Authors: Prasad D. , Henry J. G. , King A.
Published: January 2010

Studies were conducted to demonstrate the effectiveness of copper sulphate for disinfection of sewage sludge under anaerobic conditions. The effects of suspended solids and copper dosages on the survival of total coliforms in normal (neutral pH) and acidified sludges (pH 2.1–3.8) were studied. Results indicated that disinfection of sewage sludge by copper sulphate was feasible. Under anaerobic conditions, significant reductions (about 99%) of total coliform bacteria in normal sludge were achieved at a dosage of 40 mg Cu/g dry sludge mass, sludge suspended solids of < 3.0%, and a contact time of 24 h. The toxic effect of copper dosage was enhanced and the copper dosage and contact time reduced at lower pH (2.1–3.8). Sludge so treated would be suitable for land application insofar as its bacteriological quality is concerned, provided the high copper concentration could be reduced to acceptable levels. Whether this can be achieved in subsequent treatment of disinfected sludge by bacterial leaching will be determined in a future study. Key words: sludge disinfection, coliforms, copper sulphate, sludge disposal, bacterial leaching.
Free flexural vibration analysis of one-way stiffened plates by the free interface modal synthesis method
Authors: Smith Ian , Hu Lin J. , Schriver Allison B.
Published: January 2010

A numerical model is presented for predicting the natural frequencies of one-way stiffened plates with ribs having high ratios of flexural to shear rigidity. The model is based on the free interface modal synthesis method. Experimental validation using floors with wood I-joists and wood-based sheathing showed that the model has good numerical accuracy in the predictions of natural frequencies and mode shapes if analyses include shear deformation and rotatory inertia effects in ribs. Neglect of these effects can lead to large errors in the predicted natural frequencies for plates with ribs having high ratios of flexural to shear rigidity. Large errors can also be encountered in natural frequency prediction for plates with fairly low ratios of flexural to shear rigidity. This occurs with mode shapes that have multiple curvature along ribs if shear deformation and rotatory inertia effects are neglected. Key words: free flexural vibration, natural frequencies, ribbed plates, flexural rigidity, shear rigidity, modal synthesis.
Insights on the SASW nondestructive testing method
Authors: Al-Hunaidi M. O.
Published: January 2010

Spectral analysis of surface waves (SASW) is a nondestructive and in-situ method used for determining the thickness and elastic properties of pavement and soil sites using the dispersion characteristics of surface waves. In this paper, computer simulations of actual surface wave field tests are used to clarify errors that may arise in experimental dispersion curves of pavement sites when the usual test and data analysis procedures of the SASW method are followed. Two aspects of these procedures are considered: (i) relative phase angle unwrapping and (ii) source-to-near-receiver distance. The results of these simulations reveal that the currently used procedures may lead to erroneous results for some sites; the simulations offer valuable insights on the underlying causes. An overview of the theoretical aspects and field procedures of the surface wave method is briefly presented. Key words: surface waves, nondestructive testing, pavements, soils, elastic modulus.
Seasonal temperature and stress distributions in concrete gravity dams. Part 1: modelling
Authors: Léger P. , Venturelli J. , Bhattacharjee S. S.
Published: January 2010

Seasonal thermal stresses have been found to contribute significantly to the long-term degradation of strength and stiffness of concrete dams located in northern regions. Temperature variations and the associated thermal stress and strain must be evaluated to define the initial loading conditions for safety analyses and develop defensive measures to ensure the durability of the exposed surfaces. This paper presents a finite element modelling procedure to determine the thermal response of concrete gravity dams. Heat transfer and structural analysis models of a typical dam–foundation–reservoir system are developed. The reservoir, foundation, and air temperature variations, as well as solar radiation, are evaluated from data collected from different sources. The rate of convergence of the numerical solution is examined, and a methodology to identify the critical temperature states and to compute the related stresses is presented. The results of extensive parametric analyses describing the thermal behaviour of concrete gravity dams located in northern regions are presented in a companion paper. Key words: gravity dams, thermal analysis, finite element method.
Consideration of Gustafsson's proposed Eurocode 5 failure criterion for notched timber beams
Authors: Smith Ian , Springer Gerret
Published: January 2010

Experimental results and theoretical predictions for failure of timber beams with end notches, or cuts on the tension face, are discussed. The validity of Gustafsson's formula and the underlying assumptions are examined in the context of structural design codes. Attention is drawn to the arbitrary dependence of theoretical predictions on the load and geometric arrangement of specimens, and the method by which fracture energy is estimated. It is not intended at this stage to give a complete solution for the problem, but it is concluded to be premature to incorporate the proposed Eurocode 5 failure criterion for notched beams into the Canadian Standard CAN/CSA 086.1. Key words: timber, fracture, notched beam, design criterion.
THE DETECTION OF POLARIZED γ RADIATION BY THE COMPTON PROCESS
Authors: Steenberg N. R.
Published: January 2010

The general relationship between the polarization vector describing partially polarized γ radiation and the effects measurable by scattering experiments is presented. The results are applied to the radiation emitted by nuclei aligned at low temperatures and some experimental results are predicted.
CROSS-SECTION MEASUREMENTS OF REACTIONS INDUCED BY NEUTRONS OF 14.5 MEV. ENERGY
Authors: Paul E. B. , Clarke R. L.
Published: January 2010

The activation cross sections were measured for 57 elements bombarded with 14.5 Mev. neutrons from the T3(d, n)He4 reaction. Thirty-eight (n, p), twenty-five (n, α), and thirty-four (n, 2n) reactions resulting in known radioactive products with half-lives between a few seconds and a few days were observed. The counting arrangement was calibrated using samples containing standardized quantities of radioactive materials. The neutron monitor was calibrated by counting the α-particles from the T3(d, n)He4 reaction. Calculations were made of the cross sections predicted by evaporation theory and compared with the observed values. For the charged particle reactions with mass number greater than 100 the theoretical cross sections were too small. Values of σ obs/σ cal as high as 10,000 were obtained. However, the predicted cross sections for the (n, 2n) reactions were in general agreement with the observed values. A possible interpretation of these results is discussed.
THERMODYNAMICS OF SOME SPECIAL FIELDS
Authors: Krotkov R. V. , Scheidegger A. E.
Published: January 2010

The free energy, internal energy, and entropy of two quantized fields are calculated, using the method introduced by Scheidegger and McKay. The two fields examined are those representing (a) an ensemble of mesons bound by an interaction with their source (a nucleon), and (b) an ensemble of electrons perturbed by an external electromagnetic field. The presence of a source in the first case is found to have no effect on the thermodynamic functions of the mesons, while an external electromagnetic field does affect the thermodynamic functions of the electrons. Explicit formulas in the latter case are given.
A streamline solution for rigid laterally loaded piles in permafrost
Authors: Foriero A. , Ladanyi B.
Published: January 2010

A streamline solution for the design of laterally loaded rigid piles in permafrost is presented. The proposed method relies on a power law to describe the rate dependence of permafrost creep response. It describes the soil movement with a kinematically admissible velocity field and estimates the overall reaction at a given pile section with the bound theorem for a creeping material. The approach is valid only for a secondary creep rate and a stationary state of stress. Key words: pile, lateral load, velocity field, secondary creep rate.
Laboratory permeability tests on sand: influence of the compaction method on anisotropy
Authors: Chapuis Robert P. , Gill Denis E. , Baass Karsten
Published: January 2010

New laboratory results are presented on how densification influences the hydraulic anisotropy of a sand. Results are given for two compaction modes. Tests were performed at different densities in order to derive the curves kv(e) and kh(e). The samples were statically compacted in the first series and dynamically compacted in the second series. The ratio rk = kh/kv is different for the two series. It is higher than 1 for static compaction and lower than 1 for dynamic compaction. Thus, the anisotropy ratio of granular soils can take several values for the same void ratio, depending on the preparation mode. Even if the anisotropy ratios differ, the first invariant of the hydraulic conductivity tensor, 11k, is found to be a function of e only for this sand, regardless of the densification mode. The evolution of an adimensional anisotropy index, I1k/kv, versus a density index, Ie, is compared for the sand and a dispersed clay. The evolutions are nearly identical, which means that the hydraulic anisotropy of natural homogeneous soils may be similar for sediments having settled in still water and influenced subsequently by gravity only. From an engineering viewpoint, a reasonably good fit is obtained between experimental results and predictive charts. The results also demonstrate that the high apparent anisotropy often found either in natural or in compacted soils is not induced mainly by deposition or compaction but rather is due to nonuniformity or segregation in the soil mass. Key words: soil, permeability, anisotropy, laboratory, compaction.
Momentum transfer and friction in the debris of rock avalanches
Authors: Gassen W. Van , Cruden D. M.
Published: January 2010

When a mass of loose, dry, purely frictional material slides down an incline after release at a given velocity, the runout (the distance the centre of gravity of the displaced mass moves from its initial position) depends on momentum transfer within the mass. This can be estimated from the profile of the debris accumulation, which also allows more accurate calculation of apparent angles of sliding friction in rockfall avalanches. The apparent extreme mobility of the Elm and Frank slides, typical rockfall avalanches, is explained by momentum transfer in a loose, dry, purely frictional material with an angle of friction of 30°. Key words: mass wasting, momentum transfer, landslide, accumulation, rock avalanche, runout distance.
Caractérisation de l'état limite de l'argile de Pornic
Authors: Moulin G.
Published: January 2010

This paper describes a natural clay, the Pornic clay, in accordance with the yield state and critical state concepts. The author has carried out a series of axisymmetrical triaxial tests on a natural overconsolidated clay and has clearly shown the yield state curve of the material; the curve is defined as the intersection of the yield state and "overconsolidated state" surfaces. The stress-strain paths are plotted either in the original p′-q-ε-v diagram or in the normalized diagram where the stresses are defined with respect to the preconsolidation pressure [Formula: see text], thus allowing one to characterize the reciprocity of the stress and strain paths and to follow their evolution mainly near the yield state curve. Key words: clay, yield state, overconsolidated state, stress path, strain path.
Characterization of granular materials for pavements
Authors: Nataatmadja A. , Parkin A. K.
Published: January 2010

For design and analysis of flexible pavements, a simple elastic model that does not require cumbersome calculation and also can rank materials according to their performance is clearly desirable. Early studies indicated that the resilient modulus of a granular material can be taken to be a function of the first invariant of stress, θ, although there is evidence that it is also dependent on the repeated deviator stress, qr. The limitations of some earlier models are discussed herein and a simple model for granular materials is proposed. The model is empirical in nature and based on repeated load triaxial testing with constant confining pressure. The application of this model in situations where the confining pressure is pulsed in phase with the deviator stress is also discussed. Key words: repeated load, triaxial test, resilient modulus, granular materials, modelling, pavement.
GEOMETRIC AND ALGEBRAIC APPROACHES OF PLANAR STRUCTURE RECOVERY BASED ON PROPERTIES OF DUAL CONIC
Authors: WANG LIANG , YAO HONGXUN , LIU SHAOHUI
Published: December 2009

In this article, approaches of planar Euclidean Structure recovery are proposed based on the geometric and algebraic characteristics of the dual conic. Algebraic relations between the matrix representation of the dual conic and the circular point enveloped are extensively analyzed, to attain a generalized framework for the problem. The dual conic has the decomposition with consistent geometric interpretation from which the circular point envelope can be solved. From the geometric viewpoint, based on the characteristics of the common elements of dual conics (their bitangents), a stratified approach is presented to establish the solution. Experiments on both synthetic and real images are conducted to demonstrate the robustness and accuracy of the presented approach.