bluuebunny/crossref_metadata_2025 huggingface dataset:
Analyse orientée-objet et totalement désagrégée des données d'enquêtes ménages origine-destination
Authors: Trépanier Martin , Chapleau Robert
Published: April 2011

Large urban household surveys produce a huge quantity of data, generally processed with database management systems (DBMS). In most cases, data are compiled, aggregated, and then integrated in traditional transportation models. Based on another perspective, the totally disagregate approach (TDA) uses a unified survey data file in which every piece of information is preserved. The data file is used for individual analysis of households, people, and trips. The addition of an object-oriented modeling to the totally disaggregate approach permits the instantiation of survey data into objects. These objects are manipulated along with their properties and methods. New objects are derived from survey declaration and then reused in the process: status, trip generators. The enriched object-model is used for visualization, analysis, and presentation. This widens the possibilities of usage of household survey data.Key words: urban transportation, household surveys, modeling, oriented-object approach.
Microflore hétérotrophe impliquée dans le procédé simultané de biolixiviation des métaux et de digestion des boues d'épuration
Authors: Gamache M , Blais J F , Tyagi R D , Meunier N
Published: April 2011

Until now, some microbiological studies have made it possible to highlight the role and identification of certain chimiolithotroph microorganisms directly involved in the simultaneous sewage sludge digestion and metal leaching (SSDML process). Moreover, some other studies have established the performance of the SSDML process for the destruction of pathogens. However, until now no study has been carried out to define the equilibrium of the heterotrophic microbial populations during the sludge acidification occurring during the operation of the SSDML process. Hence, the SSDML process was studied in batch and continuous mode employing different types of sludges (Communauté Urbaine de Québec (CUQ)-East primary sludge, Beauceville secondary sludge, and mixture of primary and secondary Valcartier sludge). The equilibrium of heterotrophic microbial populations was investigated along with sludge acidification and solids degradation. The results obtained during the SSDML process on different sludges showed a decrease followed by the destruction of a majority of heterotrophic bacterial species found in fresh sludges. The isolation and characterization of different microbial species showed that only two types of microorganisms persisted: the yeast Blastoschizomyces capitatus and an unidentified fungus.Key words: sewage sludge, simultanous bioleaching and digestion, heterotrophic bacteria, Blastoschizomyces capitatus, fungi.
Special repairs to the Bersimis-1 generating tunnel walls to increase power production: a case study
Authors: Mirza J , Mirza M S , Roy V , Lemire C , Saleh K , Tremblay S
Published: April 2011

The intake concrete tunnel at Bersimis-1 generating station is coated with a black sticky substance (slime) approximately 5 mm in thickness. Since the tunnel is 12 km long and has an average internal diameter of 9.45 m, the deposit represents a considerable obstacle to the production of electric power. The resulting loss of power generated is estimated to be around 39 MW per year, valued at 71 million dollars. Inspections in 1979, 1981, and 1983 showed that simply cleaning the surfaces would reduce the power losses but the slime built up again after a few years. A thin, smooth protective coating, containing anti-slime agents, compatible with the existing concrete could protect the surfaces against erosion and limit the slime deposit and its harmful effect on power production. The 1993 inspection provided an opportunity both to analyze the concrete, the slime itself, and the water and to experiment with the various methods of cleaning the surface and applying the different coating products. In 1994, 11 other products were selected for the specified characteristics and applied on concrete pipes and installed at two different locations: one consisted of submerged concrete specimens in the Bersimis river and in the second test setup, the products were installed by creating an artificial environment similar to the tunnel conditions using the tunnel water. The results showed that some products do not resist these conditions. Abrasion resistance tests in the laboratory confirmed these observations. One of the eleven products, a polymer-modified cement-based mortar, passed the submersion test and was applied to a small surface area (125 m2) of the tunnel during a generating station shutdown in 1995. The thickness of the mortar required to cover the walls of the tunnel was between 2 and 3 mm. The total cost of repairing with the mortar was estimated to be between 10 and 11 million dollars. The size of the tunnel, its restricted accessibility, cleaning, ecological disposal of the slime, and the large quantities of material to be applied to cover the entire tunnel added to the complexity of the project.Key words: intake tunnel, power production, protective coating, slime deposit, surface cleaning.
Serviceability reliability of corroded steel bridges
Authors: Cheung M S , Li W C
Published: April 2011

In the present study, the serviceability reliability of corroded steel highway bridges is investigated by means of a simulation technique. At each sampling point with given values of corrosion parameters, slab thickness and elastic moduli of materials, the penetration of corrosion and the effective cross-section are calculated based on Kayser's observations. Then, a finite strip analysis of the bridge under design trucks is carried out to compute the maximum deflection of the bridge deck. If this deflection exceeds the code requirement, serviceability failure is assumed to occur, and the failure probability is determined. After the failure probability is integrated over all sampling points, the serviceability reliability of the bridge is obtained. Numerical examples are presented to illustrate the proposed methodology and to investigate the serviceability reliability of corroded steel bridges according to the AASHTO specification and Ontario Highway Bridge Design Code.Key words: serviceability reliability, corrosion, steel highway bridges, simulation, finite strip method.
Calibration of design code for buried structures
Authors: Nowak Andrzej S , Park Chan-Hee , Ojala Peter
Published: April 2011

The reliability-based calibration procedures were applied to develop load and resistance factors for the Ontario Highway Bridge Design Code (1979, 1983, and 1991) and recently the Canadian Highway Bridges Design Code (2000). However, the load components for buried structures were not considered. The development of a statistical model for earth pressure requires a special approach. Therefore, this paper deals with the reliability-based calibration of the design code for buried (cut-and-cover) structures. A typical running structure consists of reinforced concrete walls forming a rectangular box section, while an underground station may have a one- to six-cell box. The major load components include earth pressure, water pressure and weight of the concrete. Other load components such as live load are relatively small. Statistical parameters are derived for representative structures and structural systems. The correlation between load components is estimated based on the available field data. Structural performance is measured in terms of the reliability index. Reliability indices are calculated for a representative spectrum of running structures and stations. In general, the reliability indices for existing buried structures are higher than those for bridges or buildings. The target reliability index has been selected on the basis of calculated reliability indices, comparison with other structures, and cost analysis (consequences of failure). The optimum load and resistance factors are calculated and recommended for the design code to achieve a uniform safety level.Key words: buried structure, code calibration, load models, reinforced concrete, reliability analysis, resistance models.
Assessment of short-HRT, on-line, fixed-film prefermentation of domestic wastewater for enhanced biological phosphorus removal
Authors: Mavinic Donald S , Mahendraker Venkatram , Rabinowitz Barry , Dumitrescu Alexandru C , Koch Frederic A , Barnard James L
Published: April 2011

In this work, pilot-scale, on-line, short-HRT fixed-film prefermenter systems were evaluated using Ringlace and Kaldnes fixed-film media for short chain volatile fatty acid (SCVFA) production, with screened raw domestic wastewater and primary effluent. In comparison to the control reactors without media, significant levels of SCVFA were generated in the fixed-film prefermenters. For the design considered in this study, the Ringlace media performed well, whereas the Kaldnes media resulted in clogging. The Ringlace media data show that, for a 60-min HRT, on-line prefermenter systems produced 11 and 5.5 mg/L of SCVFA (as acetic acid) with screened raw wastewater and primary effluent, respectively. Such a low HRT might translate into potential cost savings (up to 25%) in providing SCVFA to enhanced biological phosphorus removal (EBPR) plants and could lead to a completely new generation of prefermenter designs.Key words: domestic sewage, enhanced biological phosphorus removal systems, fixed film, prefermenter, short chain volatile fatty acids.
Fatigue reliability of deteriorating prestressed concrete bridges due to stress corrosion cracking
Authors: Maes M A , Wei X , Dilger W H
Published: April 2011

In this paper, an analysis framework is presented to develop a relationship between fatigue reliability in a prestressed concrete bridge and the progress of stress corrosion cracking (SCC) in prestressing steel. The fatigue limit state uses a cumulative damage model for prestressing steel wires, which is a function of both stress range and minimum stress. The SCC model takes into account varying degrees of material susceptibility, stress regimes, and environmental conditions and is structured around three stages: initiation of micro-cracking, propagation, and macro-crack instability using linear elastic fracture mechanics. The framework is an overall time-dependent analysis of the safety against fatigue of a prestressed concrete bridge. It involves a stochastic analysis of the evolution of prestressing wire corrosion as a function of time and a time-dependent probabilistic analysis of the fatigue reliability of the prestressed concrete bridge suffering a certain degree of deterioration. The uncertainties involved in the fatigue model, the SCC model, and traffic actions are considered. The updating of uncertainties is simplified by considering a limited number of classes representative of the severity of SCC exposure. The framework is applied to three deteriorating highway bridges.Key words: fatigue analysis, prestressing strands, stress corrosion cracking, reliability assessment, prestressed concrete bridges, deterioration.
Motion and stability of caisson breakwaters under breaking wave impact
Authors: Wang Y -Z
Published: April 2011

The possible motions of caisson breakwaters under dynamic load excitation include vibrating motion, vibratingsliding motion, and vibratingrocking motion. Three models are presented in this paper and are used to simulate the histories of vibratingslidingrocking motions of caissons under breaking wave impact. The effect of the dynamic characteristics of the caissonfoundation system and the motions on the displacement, rotation, sliding force, and overturning moment of caissons are investigated. It is shown that the sliding force of the caisson is different from the breaking wave force directly acting on the caisson due to the motion of the caisson and the sliding motion or rocking motion of the caisson can limit the sliding force or overturning moment of the caisson to a certain value. The sliding force never exceeds the friction force between the caisson and the foundation, and the overturning moment never exceeds the stability moment of the caisson. It is concluded that the wave conditions, the dynamic characteristics, and the motions of the caissonfoundation system should be considered in design.Key words: caisson breakwater, breaking wave, vibrating, sliding, rocking.
Tractive force channel design aid
Authors: Akan A Osman
Published: April 2011

The Manning formula and the tractive force equation are combined and written in terms of dimensionless parameters. Predetermined solutions to this equation have been obtained and presented in chart form. Also, a mathematical expression is obtained that approximates the chart to determine the channel width explicitly.Key words: open channel, design, tractive force, erodible, shear stress.
Modeling simultaneous removal of primary substrates and chlorinated phenols in upflow anaerobic sludge blanket reactors
Authors: Kennedy K J , Ning Z , Fernandes L
Published: April 2011

A dynamic model describing the simultaneous degradation of easily degradable substrates (sucrose and acetic acid (HAc)) and 2,4-dichlorophenol (2,4-DCP) in upflow anaerobic sludge blanket (UASB) reactors was developed. The two critical factors considered in the model development were sorption and substrate interaction during degradation. Data obtained from experiments on the multiple substrate degradation in continuous UASB reactors were used to validate and verify the dynamic model. The model predicts the system responses for 2,4-DCP, 4-monochlorophenol (4-MCP), HAc, propionic acid (HPr), and chemical oxygen demand (COD) concentration in the effluent. The modeling results indicated that the degradation rates for 2,4-DCP and for cosubstrates, HAc and HPr, changed inversely as a function of the specific organic loading rate for UASB reactors.Key words: dynamic, modeling, UASB, 2,4-dichlorophenol, sorption, degradation, co-metablism.
Influence of cover on bond of strands prestressed by pretensioning
Authors: do Carmo Ricardo NF , Lopes Sérgio MR
Published: April 2011

Cover of prestressed tendons is an important factor that influences the transmission of prestress by bond. This paper describes a study of the influence of cover on the bond behaviour of prestressed pretensioned strands. Ten beams with different cover values were produced and tested. Bond at different levels of the percentage of transferring was studied. A second type of test was also performed to observe the behaviour of the beams when placed on two supports at the extremities and subjected to a point load at mid-span. Previous research works on bond of pretensioned tendons to concrete are presented in this paper. The experimental programme carried out at the University of Coimbra is described. Results from the tests are presented, analysed, and compared with Canadian, American, and European regulations. The results show that, in general, when the cover increases the transmission length decreases. A bilinear relationship between the transmission length and the cover is presented. The beams were placed simply supported and tested up to failure by means of a point load at mid-span. These tests showed that beams with a 20-mm cover withstood a load significantly lower than that predicted theoretically.Key words: prestress, bond, cover, concrete beams, prestressed structures, structural concrete.
Sensitivity of shear strength to fracture energy of high-strength concrete slabs
Authors: Marzouk H , Emam M , Hilal M S
Published: April 2011

The test results of an earlier experimental investigation conducted at Memorial University of Newfoundland on high-strength concrete slabs indicated that as the concrete slab strength increased from 35 to 75 MPa the shear strength increased by 7-20%, depending on the case of loading, i.e., concentric or eccentric loads. The increasing ratio of shear strength is less than half that prescribed in the Canadian code CSA-A23.3 (1994) or the ACI-318 code (1995). Hence, the significant difference between the experimental results and the predicted strength by existing North American codes tacitly means that the proportionality between the shear strength and the square root of the compressive strength is not accurate enough to predict the shear strength of high-strength concrete slabs. In the present investigation, a fracture mechanics model suitable for concrete was proposed. It was also suggested that this model might be an advantageous aid in the analysis of the shear failure of reinforced concrete slabs. In this research investigation the fracture mechanics approach utilizing finite element aided computer analysis of several reinforced slabs is briefly described, and calculated shear failure loads are given. The recommended model proves that it is necessary to consider not only the tensile strength of concrete, instead of the square root of the compressive strength, but also the tensile fracture properties of high-strength concrete. The tensile fracture properties of concrete are characterized by the parameter called characteristic length and the brittleness of concrete. The brittleness ratio of concrete slabs must be considered in any rational shear design expression to reflect the size effect factor and the aggregate type.Key words: fracture energy, uniaxial direct tension, shear strength, high-strength concrete, punching shear, slab, size effect, finite element analysis.
Lateral and withdrawal load resistance of glulam rivet connections made with sawn timber
Authors: Karacabeyli E , Fraser H , Deacon W
Published: April 2011

The efficiency of glulam rivets has made them one of the most suitable connectors in heavy timber construction utilizing glued-laminated timber (glulam) members. Starting with the 1994 version of the CSA Standard for Engineering Design in Wood, design procedures are also available for the use of glulam rivet connections with sawn timbers. In the course of formulating these design provisions, several series of lateral resistance and withdrawal tests were performed using glulam rivets with sawn timbers to study the effects of material (sawn timber versus glulam), species, loading type and direction, environmental conditions, density, waiting period between assembly and test, pre-drilling, and plate thickness. The newly added design provisions increase structural engineers' choice of fastening systems in timber construction.Key words: glulam rivets, fasteners, connections, timber.
Ice loads from first-year ice ridges and rubble fields
Authors: Blanchet Denis
Published: April 2011

A method for estimating global loads from consolidated first-year ice ridges and rubble fields on wide Arctic offshore vertical-sided structures is presented. The method utilizes full-scale global ice load measurements in the Arctic to represent the failure behavior of the consolidated layer and a Mohr-Coulomb approach for the remaining layers. By including full-scale data, the model can take into account the effects of scale and non-simultaneous failure of the consolidated ice layer across the structure width. The results are compared with those obtained from several other first-year ice ridge and rubble field load models.Key words: first-year ice ridges, rubble fields, ice load and pressure measurements, Arctic structures, ice load models.
Interpretation of pavement deflection measurement data using an elastodynamic stochastic approach
Authors: Parvini Mehdi , Stolle Dieter FE
Published: April 2011

Pavement deflection measurements, together with backcalculation procedures, are widely used to estimate the layer moduli of pavement-subgrade systems. Sensitivity analysis of a sample problem indicates that conclusions drawn from static analyses with regards to deflection sensitivity to variation in layer moduli may apply when characterizing uncertainty associated with the interpretation of the falling weight deflectometer (FWD) data. The uncertainty associated with the values of the backcalculated parameters from deflection data is investigated in this paper using an elastodynamic, stochastic finite element approach. The results of the simulations indicate that, in order to properly estimate surface layer moduli, loading frequencies higher than that of excitation by typical FWD loading are required. The low sensitivity of deflection uncertainty to random variations in surface modulus, when compared with that associated with subgrade modulus, is demonstrated to contribute to high variations in backcalculated surface modulus from measured surface deflections. Although focus is placed on uncertainties in elastic modulus and deflection, the methodology presented in the paper can be used to quantify uncertainties associated with other layer properties and pavement responses.Key words: stochastic, finite element, pavement deflection, elastodynamic, backcalculation, layer moduli, falling weight deflectometer test.
Use of the mixing length concept to correctly reproduce velocity profiles of turbulent flows
Authors: Robert Jean-Loup , Khelifi Mohamed , Ghanmi Ahmed
Published: April 2011

Since the viscous analogy of turbulence was introduced by Reynolds, many formulations for turbulent viscosity have been proposed. One of them, based on the mixing length concept, is investigated here in a broader point of view. The mixing length concept was used to correctly model turbulent velocity profiles for irregular two-dimensional and three-dimensional domains. Two cases of study were investigated for this purpose: a simple two-dimensional aerodynamic problem and a more complicated three-dimensional hydraulic problem. Results showed that the use of a constant viscosity fails to correctly reproduce experimental observations. On the other hand, the use of the mixing length concept leads to a good agreement between the measured and predicted values.Key words: fluid flow, finite element method, mixing length flow theory, turbulent flow, velocity profiles.
Compatible ground-motion time histories for new national seismic hazard maps
Authors: Atkinson Gail M , Beresnev Igor A
Published: April 2011

Ground-motion time histories which are compatible with the uniform hazard spectra (UHS) provided by the new national seismic hazard maps of the Geological Survey of Canada (GSC) are simulated. Time histories are simulated for the following cities: Halifax, La Malbaie, Québec, Montreal, Ottawa, Toronto, Prince George, Tofino, Vancouver, and Victoria. The target UHS for the time history simulations are the GSC 5% damped horizontal-component spectra for "firm ground" (Class B) sites for an annual probability of 1/500. The Canadian Council on Earthquake Engineering is currently considering the adoption of these maps as the seismological basis for the earthquake design requirements for future editions of the National Building Code of Canada. It is therefore useful to have compatible time histories for these spectra, in order that dynamic analysis methods requiring the use of time histories can be employed. The simulated records provide a realistic representation of ground motion for the earthquake magnitudes and distances that contribute most strongly to hazard at the selected cities and probability level. For each selected city, two horizontal components are generated for a moderate earthquake nearby, and two horizontal components are generated for a larger earthquake farther away. These records match the short- and long-period ends of the target UHS, respectively. These simulations for local and regional crustal earthquakes are based on a point-source stochastic simulation procedure. For cities in British Columbia, records are also simulated for a scenario M8.5 earthquake on the Cascadia subduction zone, using a stochastic finite-fault simulation model. Four different rupture scenarios are considered. The ground motions for this scenario event are not associated with a specific probability level, but current information suggests that their probability of occurrence is comparable to that of the 1/500 UHS (the probabilistic analyses performed for the national hazard maps do not explicitly include the Cascadia subduction event). Thus it would be reasonable to conduct engineering analyses for cities in British Columbia using both the simulated crustal-event motions and the simulated Cascadia-event motions for the Cascadia event. The time histories simulated for this study are available free of charge to all interested parties.Key words: compatible time-histories, seismic hazard, ground motions.
Apport des mesures respirométriques à la gestion d'une station d'épuration à boues activées
Authors: Weiss B , Roche N , Potier O , Pons M -N , Gauthier S , Prost C
Published: April 2011

New regulations for wastewater treatment that will insure greater reliability of the wastewater treatment plants are being established, that is to say in the case of an activated sludge plant, a better control of the biological process. The use of biological sensors would appear to increase the reliability of the plants by allowing the assessment of some characteristic variables of the process and by detecting as quickly as possible the influx of a toxin that is able to inhibit the biomass. We created a biosensor that measures oxygen uptake rates. According to the first results obtained, the data could lead to a good control strategy of the activated sludge process.Key words: wastewater treatment, activated sludge, respirometry, control.
Representing a project's physical view in support of project management functions
Authors: Russell Alan , Chevallier Nicola
Published: April 2011

In performing project management functions such as scheduling and project control, construction professionals base much of their reasoning on the physical characteristics and context of the work. And yet this project view is missing in virtually all management systems commonly used in construction, which focus almost exclusively on the process or activity view of a project. It is believed that the facility to provide the physical view of a project is both central and a priority to the development of computer-integrated project management systems in order to successfully imitate and support the thought processes of construction personnel. This paper describes several of the design considerations and features of a parametric modelling module capable of providing such a view. Two of a broad range of applications supported by this module, automatic draft plan and schedule generation and productivity analysis, are briefly described in order to demonstrate the value added by integrating the process and physical views of a projectKey words: computer-integration, physical component breakdown structure, parametric modelling
An expert-hypertext system for water chlorination and chloramination operations
Authors: Bather Ansel , Andrews Robert C , Hunsinger Ronald
Published: April 2011

The importance of operators' knowledge in the production of high-quality water and the need for consistent high-level expertise have fueled propositions for the application of computer technology, including knowledge-based expert systems (KBES), as a means of enhancing drinking water treatment operations. With this in mind, the authors have developed CHLOROS, a knowledge-based system which integrates both expert system and hypertext technologies in a WindowsTM environment. Designed as an off-line tool, the system does not directly control operations related to drinking water disinfection, but rather has been intended to assist treatment plant operations personnel. It is believed that CHLOROS will serve as a practical tool for water utilities because it creates a consistent decision-making environment, captures and preserves the expertise of human experts, and reduces the amount of manual effort and time that may be expended by searching through manuals and literature for information that is required to support the choice of control parameters.Key words: knowledge-based systems, expert system, hypertext system, disinfection, chlorination, chloramination.
Improved curve number selection for runoff prediction
Authors: Perrone J , Madramootoo C A
Published: April 2011

The three antecedent moisture conditions used in the SCS (Soil Conservation Service) curve number method of surface runoff volume prediction have been shown to be inapplicable in humid regions such as the Ottawa - St. Lawrence Lowlands. The antecedent precipitation index is an alternative indicator of soil moisture. Using a hydrologic database, calibration curves were developed to correlate antecedent precipitation index to the SCS curve number. Curve numbers were then input to the AGNPS hydrologic model. When compared to the three antecedent moisture conditions in the SCS curve number method, use of antecedent precipitation index as a soil moisture indicator considerably improved surface runoff volume simulations. However, peak flow was generally overpredicted by the AGNPS model.Key words: AGNPS, antecedent moisture, curve number, peak flow, surface runoff, hydrologic modeling, precipitation.
Torsional motion of buildings during earthquakes. II. Inelastic response
Authors: Humar J L , Kumar P
Published: April 2011

In a previous study on the elastic torsional response of building models subjected to earthquake motion, it was shown that the current provisions of the National Building Code of Canada for design against torsion induced by earthquakes are quite conservative for the flexible edge of the building, but may be inadequate for the stiff edge. Based on the results of studies on the elastic response, a new set of design provisions was suggested. The present study deals with the inelastic torsional response of single- and multi-storey buildings designed according to the suggested provisions. Effects of both the natural and the accidental torsion are considered. It is shown that, given the complexity of inelastic response, particularly that of multistorey buildings, the suggested provisions can reasonably be used for the torsion design of single-storey buildings, as well as of multistorey buildings that are asymmetric in plan, but otherwise fairly regular.Key words: earthquake response, natural torsion, accidental torsion, inelastic torsional response, design for torsion.
Validation en temps réel des données des apports naturels journaliers pour la gestion des réservoirs
Authors: Nguyen Van-Thanh-Van , Bisson Jean-Louis
Published: April 2011

The main objective of this study is to propose a method for validating the daily net basin supply data to obtain the most reliable values for the management of water resource systems. Based on the regression and exponential smoothing methods, various validating procedures are developed and compared. Results of a numerical application using data from La Grande 3 basin have shown that the simple exponential smoothing method is the most suitable. Further, it has been found that the proposed exponential smoothing has the simplest structure and would require a simple parameter estimation method because it contains only one parameter.Key words: real time validation, net basin supply, forecasting, time series analysis, reservoir management.
Simplified seismic code design procedure for friction-damped steel frames
Authors: Fu Yaomin , Cherry Sheldon
Published: April 2011

This paper describes the development of a proposed seismic design procedure for friction-damped steel structures, which employs the lateral force provisions used in many modern building codes. Closed-form expressions are first derived that relate the normalized response of a single degree of freedom friction-damped system with the system parameters, such as bracing stiffness ratio, damper slip ratio, and frame member ductility. A parametric analysis is then used to reveal that the seismic displacement of a friction-damped frame can be controlled by combining the frame stiffness with the bracing stiffness of the friction damper component, while the seismic force can be controlled by the damper slip force. A force modification factor (equivalent to the code R-factor) and displacement estimate for a friction-damped system are next determined. The single degree of freedom results are subsequently used to develop expressions for dealing with the multi degree of freedom situation, which permits the seismic lateral force design procedure adopted by many current building codes to be applied to friction-damped systems. The proposed procedure allows the frame response to be controlled so that the displacement can be limited to small magnitudes and the overall structural shape to an essentially straight-line deformation. Design examples illustrate that friction-damped frame systems are economical and offer a better overall response performance than that provided by conventional systems under the design earthquake.Key words: passive energy dissipation system, friction damper, steel frame, design procedure, static analysis.
Prestressed high-strength concrete beams under torsion and bending
Authors: Ashour Samir A , Shihata Sabry A , Akhtaruzaman Ali A , Wafa Faisal F
Published: April 2011

Test results of 16 rectangular prestressed high-strength concrete beams subjected to the combined action of torsion and bending are presented. The major variables were the ratio of torsion to the bending moment (T/M) and the prestressing level. The beams were subjected to two levels of prestressing, corresponding to 0.05fc' and 0.10fc', where fc' is the compressive strength of concrete (about 90 MPa). Test results showed that the torque-twist relations for the test beams were approximately linear up to cracking and thereafter became nonlinear. Increasing the T/M ratio and the prestressing level increases both torsional stiffness and strength. Several theoretical methods available in the literature developed for normal-strength concrete were used to predict the torsional strength of the tested high-strength concrete beams. Interaction equations were used along with some other methods to predict the torsional capacity in the presence of a bending moment. Good agreement was observed between the experimental and theoretical results.Key words: beams (supports), bending, cracking, failure, high-strength concrete, interaction diagram, prestressed concrete, stiffness, torsion, torsional strength.
Inelastic instability of rectangular and nonrectangular frames
Authors: Kemp A R
Published: April 2011

Proposals are described for extending the elastic amplification approach to frame instability given in the Canadian and South African codes for structural steel design to both nonrectangular frames and material inelasticity. The proposed approach to generalized nonrectangular frames is based on sway equilibrium equations which are derived by the principle of virtual work for each independent mode of sway collapse. The influence of material inelasticity is assessed by idealizing the moment-curvature relationship and the load-deflection behaviour between an effective elastic limit and the formation of the plastic collapse mechanism. A number of examples are given which demonstrate both the simplicity and accuracy of the method.Key words: codes, design, frames, inelastic properties, plastic properties, stability.
Hydraulic jump in circular pipes
Authors: Stahl Helmut , Hager Willi H
Published: April 2011

Hydraulic jumps in conduits containing free surface flow have received practically no attention. This project was conducted to investigate experimentally the main features of such jumps and to obtain limits for conduit choking. The sequent depth ratio is determined in terms of the approach Froude number based on the conventional momentum approach. The lengths of the surface recirculation and aeration zones are also considered. Two different appearances of jumps are discussed and it is demonstrated that jumps with a small approach depth differ from those with a depth larger than about 30% of the conduit diameter. A choking condition is proposed for which conduits are subjected to full pipe downstream flow. Photographs are used to describe the main flow pattern. The results of this study are readily applicable for design.Key words: aeration, conduit choking, hydraulic jump, pipe flow, sequent depths.
Prévision des vagues dans l'estuaire du Saint-Laurent à l'aide d'un modèle bidimensionnel
Authors: Dupuis L , Ouellet Y
Published: April 2011

Until now, wave hindcasting in the Estuary and Gulf of St. Lawrence has been done with one-dimensional models. The objective of the present paper is to verify if the two-dimensional model WAWSP, developed to predict waves on the Great Lakes, could be used in the St. Lawrence estuary, a semi-open fetch limited region. Waves (significant wave heights, peak periods, and directions) hindcast by this 2D model are compared with wave data observed at two buoys in 1991, 1992, and 1993, as well as with the ones obtained with 1D models SPM-77 and SPM-84. As a whole, the 2D model gives better results than 1D models. Wave heights are well reproduced, as long as wind data are well represented. However, wave periods are much smaller than those measured, and wave directions are not accurate, mainly because of the presence of swell in the estuary. This study shows the need to obtain more wave data with better quality in order to validate wave hindcasting models.Key words: water waves, numerical modeling, wave hindcasting, 2D model, wave climate, wave height, wave period, wave direction, calculated versus measured waves.
Shear strain effects on flexure and torsion of thin-walled pultruded composite beams
Authors: Kabir Mohammad Z , Sherbourne Archibald N
Published: April 2011

The paper presents a theoretical study on the static structural response of thin-walled composite open-section beams. Based on a Vlasov-type linear hypothesis, a beam theory is formulated in terms of in-plane elastic properties to analyze composite I and channel section pultruded beams which includes the transverse shear deformation of the beam cross section. The importance of the shear influence on the total vertical deflection is reported. Symmetric lay-up composite beams result in a bending-twisting structural coupling. The optimal fibre orientation for minimizing vertical displacements and twist angle is also investigated.Key words: pultruded, shear strain, composite beams, twist.
Déshydratation des produits de décontamination des cendres volantes d'incinérateur de déchets municipaux
Authors: Marcotte C , Blais J F , Mercier Guy , Roberge G
Published: April 2011

Municipal solid waste combustion fly ash handling costs are increasingly expensive because of the increase of the landfilling cost. A research team from the Institut national de la recherche scientifique (INRS-Eau) developed, in association with the private sector, a fly ash decontamination process. Once treated by this process, two types of sludges are produced. The first type of sludge consists of a decontaminated ash, while the second is a residual metal sludge. This research project aimed to show that these sludges could be dewatered economically with standard filtration devices, under normal operating conditions. This paper demonstrates that sludge conditioning can easily be achieved by adding a small amount of commercial polymers, [Formula: see text]0.5 kg per ton of dry weight. Two types of commercial dehydration equipment were compared: a filter press and a vacuum filter. For the ash sludge, these two types of equipment produced a filtration cake containing more than 40% in total solids. For the metal sludge, total solids were 20% for the filter press. Vacuum filter efficiency was significantly lower with a total solids of only 13%. An economic analysis showed that the use of a filter press for both sludges was the best choice.Key words: fly ash, decontamination, dehydration, filter press, vacuum filter, conditioning, metal.
Impact of highway consistency on capacity utilization of two-lane rural highways
Authors: Gibreel Gamal M , El-Dimeery Ibrahim A , Hassan Yasser , Easa Said M
Published: April 2011

Consistent highway design is expected to provide safe, economical, and smooth traffic operation. Several studies have been performed to investigate the effect of highway consistency on traffic safety. However, the relationship between design consistency and highway capacity and level of service has not been addressed in current research work and design practices. In addition, the effect of the three-dimensional (3D) nature of highway alignments was not considered, and design consistency was studied based solely on two-dimensional (2D) analysis of highway horizontal alignments. This paper presents a methodology to determine the effect of highway design consistency on highway capacity utilization based on 3D analysis. This methodology will help road designers to estimate highway capacity more accurately. The study was performed on two-lane rural highways in Ontario, where two types of 3D combinations were considered: a horizontal curve combined with a sag vertical curve (sag combination) and a horizontal curve combined with a crest vertical curve (crest combination). An additional adjustment factor that reflects the effect of highway design consistency on capacity utilization was developed. Different statistical models are introduced to estimate this factor based on geometric or traffic data. In addition, typical values of the consistency factor were developed based on an overall consistency evaluation criterion and can be easily used in capacity analysis.Key words: three-dimensional, alignments, capacity, geometric design, operating speed, design consistency.
Seismic behavior of slab-column connections
Authors: Megally Sami , Ghali Amin
Published: April 2011

Brittle punching failure of flat plates can occur as a result of transfer of shearing forces and unbalanced moments between slabs and columns. During an earthquake, the unbalanced moments transferred between slabs and columns can produce significant shear stresses that increase the likelihood of brittle failure. This brittle punching failure mode must be avoided for seismic-resistant flat plate structures. The most common punching strengthening methods are provision of the slab-column connections with drop panels or shear reinforcement or use of high strength concrete in the slab at the vicinity of the connections. This paper compares the effect of these punching strengthening methods on the ductility of slab-column connections. The results of a part of an extensive experimental program conducted on edge slab-column connections, without and with shear reinforcement, are presented. The experiments show that provision of stud shear reinforcement results in seismic-resistant slab-column connections, in which brittle punching failure is avoided in severe earthquakes. The connections with stud shear reinforcement can undergo ductile deformations associated with up to 5% lateral interstorey drift ratio, without loss of resistance to punching due to gravity loads. Key words: concrete design, ductility, energy dissipation, flat slabs, lateral drift, moment transfer, punching, seismic, shear strength, slab-column connections, stiffness, stud shear reinforcement.
A preliminary study of the factors affecting the cost escalation of construction projects
Authors: Knight Karla , Fayek Aminah Robinson
Published: April 2011

An interview survey of Alberta-based construction contractors was conducted in July and August 1998. The purpose of this survey was to elicit information on the factors that cause unanticipated project cost escalation during construction, from the contractor's perspective. This paper presents the findings of this survey and a proposed method of modeling the factors identified. The majority of factors identified impact labour productivity, which is a major source of cost overruns. A combination of subjective, objective, and secondary indicators are used to measure these factors and to assess their impact on project performance. The main conclusion of this survey is that many of the factors affecting the cost of construction are evaluated in subjective and imprecise terms and are difficult to quantify. This paper presents a method of modeling these factors using fuzzy membership functions, which capture the imprecision and subjectivity associated with the measurement of these factors. It discusses a basis for the definition of these membership functions and a method of calibrating these functions to make them more widely applicable to suit different contexts. These membership functions are being incorporated in a set of expert rules, which reason about the factors affecting costs, their impact on the project, and the appropriate corrective actions. These expert rules are being developed as part of a fuzzy expert system for construction project monitoring and control. A method of calibrating membership functions to suit individual contexts is currently being developed, which would be a significant advancement in the area of fuzzy logic. Key words: construction, costs, expert systems, fuzzy logic, project control, survey.
Monitoring suspended sediment plumes by optical and acoustical methods with application to sand capping
Authors: Hamblin Paul F , Zhu David Z , Chiocchio Fausto , He Cheng , Charlton Murray N
Published: April 2011

There is a need to rapidly survey plumes of suspended sediment and to determine the quantity and transport of disturbed material that might arise from industrial and remedial activities in lakes and harbours. The example of sand capping of contaminated bottom sediments is used to illustrate the methodology. Capping of contaminated bottom sediments is one strategy for immobilizing contaminants. In a pilot-scale project, a 0.34 m thick cap of clean sand was deposited over a one hectare area in Hamilton Harbour. The objective of this study was to determine if in-place sediments could be disturbed by the capping operation. In the first of three approaches, the suspended sediment plumes created during the capping operation were monitored for evidence of suspension of bottom materials with underwater acoustic and optical profilers and other moored instruments. In-lake calibration of the instrumentation was based on the collection of over 300 grab samples. Three-dimensional rendering of a dense network of acoustic backscatter profiles revealed that there was no evidence that bottom sediment was resuspended. The density current flowing downslope close to the bottom caused by the capping material was examined and found too weak to erode bottom sediments. Finally, a quantitative estimation of the amount of sediment suspended in the plumes indicated little evidence for resuspension of in-place sediments. The methodology developed could also be applied to estimate the concentration and quantities of contaminants in sediments suspended by other remedial activities such as dredging. Key words: suspended sediment plumes, underwater acoustics, optical measurements, sediment remediation, harbours, lakes.
Développement d'une méthodologie de repérage des conduites d'aqueduc présentant des fuites
Authors: Paquin F , Babineau D , Brissette F , Leconte R
Published: April 2011

The present article deals with the problem of leaks in drinking water distribution networks. Because of monetary losses related to those leaks, and of the current municipal context, it is important to reduce them to an acceptable level. Several techniques allow efficient elimination of leaks. However, when municipalities wish to set up a program for leak elimination on their networks, these techniques can turn out to be expensive. This research aims at developing a new technique which allows municipal managers to target the most problematic sectors or pipe reaches. Unlike the other techniques, this one is based on the study of pressure drops caused by leaks. This new leak detection approach presents a certain advantage by providing municipalities with a general idea on the leak problem which affects their networks as a whole. The proposed technique allows the identification of sectors or pipes affected with leak problems so that it is possible to identify more precisely which ones request a more extensive auscultation through other existing techniques. The costs related to the use of these techniques might be reduced as a result of an efficient preliminary diagnosis.Key words: pipe, detection, water, leak, infrastructure, tracking, pressure, network.[Journal translation]