bluuebunny/crossref_metadata_2025 huggingface dataset:
Analyse expérimentale de l'effet d'un couvert de glace sur la propagation de l'onde de rupture de barrage
Authors: Fuamba Musandji , Marche Claude , Quach Tung
Published: April 2011

Lengthy winter conditions such as those known in the province of Quebec require that one takes the presence of an ice cover into account in the determination of instantaneous safety factors for dams established in cascade and under the effect of a break wave. Not only should the ice load on the structure be considered but also the effects of the pressure wave that is propagated under the ice cover. This study shows that the method currently used to determine the stability of structures subject to a break wave is incomplete. The results obtained in laboratory indeed indicate that the presence of the ice cover increases the sur-elevation and sur-pressure values of both components of the break wave. This might perturb the stabilizing force balance of the downstream dam and increases its risk of failure.Key words: dam safety, break wave, ice cover, sur-pressure, dynamic load.[Journal translation]
Effect of route guidance and route scheduling systems on courier pickup and delivery operations: a simulation study
Authors: Choudhry Omar H , Khan Ata M
Published: April 2011

The efficiency of pickup-and-delivery (P&D) activities of urban courier is adversely impacted by traffic congestion and lack of logistical innovations. The high frequency of P&D tasks offers the opportunity to achieve substantial savings in time through the implementation of route optimization, route guidance, and scheduling innovations. These innovations would require the intelligent transportation systems (ITS) technologies for their implementation. This paper describes how such time savings can be obtained. For testing the effect of network and operating conditions on time savings, a simulation study was undertaken on synthesized networks and logistical requirements. The results show that route guidance and scheduling systems yield highly significant time savings in the P&D operation of the courier industry.Key words: courier, intelligent transportation systems, route guidance, route planning, simulation.
An analytical solution for an infinite pavement strip on elasticfoundation
Authors: Chen Y , Deng X
Published: April 2011

In this paper, continuously reinforced concrete pavement (CRCP) and the reinforced plate of CRCP are treated as an infinite pavement strip and a laminated plate, respectively. The equilibrium equations of pavement on semi-infinite elastic foundation are established according to the classical theory of anisotropic and unsymmetrical composite plate. Analytical solutions of the equations are obtained from expanding the distribution of the vertical load into double Fourier's series. The good agreement of the results of the present method, ANSYS code, and CP05 code verified the validity of the present method. Several examples are given and the following can be concluded: (i) the variation of the elastic modulus of the foundation has no apparent influence on the displacements of CRCP; (ii) the variation of the thickness of the plate influences considerably the displacements of the pavement; (iii) the variation of the reinforcement location has little influence on the stresses of the pavement; (iv) there is little influence on the displacements of the slabs with the variation of steel ratios in CRCP; and (v) the configuration of the load has apparent influence on the displacements of the pavement. The results of this study are applicable to the design and construction of CRCP.Key words: infinite pavement strip, CRCP, composite material, anisotropy, semi-infinite elastic foundation, load stress, analytical solution.
Flood frequency analysis for the Red River at Winnipeg
Authors: Burn Donald H , Goel N K
Published: April 2011

This paper reviews the flood frequency characteristics of the Red River at Winnipeg. The impacts of persistence in the flood series on estimates of flood quantiles and their associated confidence intervals are examined. This is done by generating a large number of data sequences using a mixed noise model that preserves the short-term and long-term correlation structures of the observed flood series. The results reveal that persistence in the data series can lead to a slight increase in the expected flood magnitude for a given return period. More importantly, persistence is shown to dramatically increase the uncertainty associated with estimated flood quantiles. The 117-year flood series for the Red River at Winnipeg is demonstrated to be equivalent to roughly 45 years of independent data.Key words: flood frequency, extreme events, simulation, historical data.
Deformation and ductility considerations of ductile coupled shear walls located in Canadian seismic regions
Authors: Chaallal O , Gauthier D
Published: April 2011

This paper presents the results of an analytical study on the nonlinear deformation and ductility response of reinforced concrete ductile coupled shear walls (CSWs) under seismic loadings. The CSWs were designed, calculated, and detailed in compliance with the National Building Code of Canada (NBCC) 1995 and the Canadian Concrete Standard CAN3-A23.3-94. The parameters and assumptions of the study as well as the description of the models and the procedure were fully described elsewhere. Results indicated that the maximum interstorey drift from dynamic analyses was well below that obtained from static analyses with NBCC specified lateral forces. It was also found to be substantially lower for tall CSWs compared to short or medium-height walls, and decreased only slightly as the degree of coupling increased within the range considered in this study. It was also highest for seismic records with low PGA/PGV ratios. Plastic hinge rotations as well as accumulated plastic hinge rotations generally decreased as the number of storeys increased. The maximum displacement ductility demand factor remained below the NBCC value of 4.0 specified for ductile CSWs. The influence of degree of coupling on the maximum displacement ductility demand factor was found negligible. Also, the maximum displacement ductility demand factor generally decreased as the number of storeys increased. The maximum rotational ductility demand factor in coupling beams decreased as the number of storeys increased and was generally less than the practical accepted limit of 10, except for a few short CSWs.Key words: coupled shear walls, reinforced concrete, seismic, degree of coupling, frequency content, interstorey drift, plastic hinge deformation, ductility.
Min-max goal programming: an application to Mahanadi Reservoir Project Complex
Authors: Verma M K , Shrivastava R K
Published: April 2011

An application of the min-max goal programming methodology to a system of multipurpose reservoirs for optimal monthly operation has been presented in this paper. The goal programming approach possesses significant advantages because of the fact that it may be based on physical operating criteria. The system goals and constraints are expressed deterministically. A constraint must be strictly satisfied, while for a goal it is desired to achieve the solution, which is as close as possible to the specified target. The min-max goal programming model is developed and applied to the Mahanadi Reservoir Project (MRP) Complex comprising of six multipurpose reservoirs in the state of Madhya Pradesh, India. The MRP Complex operations resulting from the use of the min-max goal programming model are compared to the operations resulting from three other reported optimization models with the same data set for the same operation period. The set of operations resulting from various models are comparable in their effectiveness, and in most aspects the min-max goal programming model operations are better.Key words: optimization, reservoir operation, goal programming, min-max goal programming.
New visualization method for civil engineering  calibration-free augmented reality based on vision
Authors: Shen Jie , Liu Haowu
Published: April 2011

As a new visualization method, calibration-free augmented reality based on vision is presented. It is convenient to apply this method to civil engineering. The main ideas of this method and an application example are given in this paper. Its application is successful.Key words: visualization, augmented reality, virtual reality, affine representation, vision.
Application of low yield strength steel on controlled plastification ductile concentrically braced frames
Authors: Chen Cheng-Cheng , Chen Shyh-Yeang , Liaw Jiunn-Jye
Published: April 2011

The hysteretic behavior of buckling inhibited braces (BIBs) (or unbonded braces) made of low yield strength steel is investigated experimentally. Test results from four large-scale specimens showed that the BIB is able to prevent early buckling and cracking that occur in conventional braces and develop to the full capacity the strength, ductility, and energy-dissipation capacity of the steel used. In addition, the use of low yield strength steel results in small yield deformation and dramatic strain hardening of the BIB. Earthquake simulation tests of a 0.4-scale three-storey ductile concentrically braced frame (DCBF), which employed low yield strength steel BIBs as concentric braces, were carried out. Test results verified the applicability of the BIB and the high seismic performance of the DCBF. The idea of controlled plastification worked well. In addition, both the 70% lateral-force distribution requirement of the Uniform Building Code and the 30% lateral-force distribution requirement of CAN/CSA-S16.1-94 seem unnecessary for a DCBF system.Key words: concentrically braced frames, earthquake-resistant structures, braces, steel structures.
Estimation of Yukon River discharge during an ice jam near Dawson City
Authors: Jasek Martin , Muste Marian , Ettema Robert
Published: April 2011

The paper presents two approaches used independently to estimate river discharge during an ice jam on the Yukon River near Dawson City. One method entailed the use of large-scale particle image velocimetry to obtain surface velocities, which were extrapolated and integrated to yield a discharge. Videotaping of ice-floe drift comprised the measurement method used for the large-scale particle image velocimetry. The second approach entailed numerical simulations performed with a 1-D ice-jam profile model (ICEJAM). The numerical model incorporates an "island-compensation" technique developed to take into account the difficulty of using 1-D ice-jam profile models to simulate accurately channels with two-dimensional features such as islands and bars. The two approaches yielded closely comparable estimates of river discharge.Key words: discharge, velocity, measurement, river, ice, jam, particle, image, velocimetry, islands.
Rehabilitation of bridges using aluminum decks
Authors: Arrien Paul , Bastien Josée , Beaulieu Denis
Published: April 2011

The rehabilitation of highway and road bridges is without any question one of today's major challenges. It is to keep up with this challenge that this paper presents an innovative bridge rehabilitation technique which consists in using aluminum decking to replace deteriorated bridge decks. Numerical modeling was carried out on a favored type of decking in order to study and analyze its performance under Canadian traffic loads. Also, an economic analysis was made on a case-study bridge, in order to compare the costs of the proposed technique to the cost of the method currently used by the Quebec Ministry of Transportation for the rehabilitation of certain types of bridge deck.Key words: aluminum, bridge, deck, economic study, extrusion, grid method, rehabilitation.
Au sujet du débit maximal de la rivière Mistassibi durant la période printanière
Authors: Lefebvre Mario
Published: April 2011

First a stochastic model is found for the maximal flow of the Mistassibi river, in Québec, during each of the months of April, May, and June, as well as for the maximal flow during the 3-month period. Next, the problem of forecasting the maximal flow in May, based on the maximal flow in April, is considered.Key words: stochastic modeling, hydrological forecast, Gaussian distribution, lognormal distributrion, linear regression, correlation, peak criterion.
Accounting for overstrength in seismic design of steel structures
Authors: Rahgozar M A , Humar J L
Published: April 2011

Observations during many earthquakes have shown that building structures are able to sustain without damage earthquake forces considerably larger than those they were designed for. This is explained by the presence in such structures of significant reserve strength not accounted for in design. Relying on such overstrength, many seismic codes permit a reduction in design loads. The possible sources of reserve strength are outlined in this paper, and it is reasoned that a more rational basis for design would be to account for such sources in assessing the capacity rather than in reducing the design loads. As an exception, one possible source of reserve strength, the redistribution of internal forces, may be used in scaling down the design forces. This is because such scaling allows the determination of design forces through an elastic analysis rather than through a limit analysis. To assess the extent of reserve strength attributable to redistribution, steel building structures having moment-resisting frames or concentrically braced frames and from 2 to 30 storeys in height are analyzed for their response to lateral loading. A static nonlinear push-over analysis is used in which the gravity loads are held constant while the earthquake forces are gradually increased until a mechanism forms or the specified limit on interstorey drift is exceeded. It is noted that in moment-resisting frames the reserve strength reduces with an increase in the number of storeys as well as in the level of design earthquake forces. The P→Δ effect causes a further reduction. In structures having braced frames the main parameter controlling the reserve strength is the slenderness ratio of the bracing members. In these structures, reserve strength is almost independent of both the height of the structure and the effect of building sway. Key words: seismic design, overstrength factor, reserve strength owing to redistribution, steel moment-resisting frames, steel-braced frames, push-over analysis.
Vibrations of horizontally curved continuous composite cellular bridges
Authors: Sennah Khaled , Kennedy John B
Published: April 2011

The use of cellular-shaped cross sections for highway bridges, especially on curved alignments, is an economical solution because of the high flexural and torsional strength of such sections. This paper summarizes the dynamic characteristics of curved composite multi-cell (contiguous boxes) bridges, continuous over two and three spans. An extensive parametric study, using the finite-element method, was conducted to evaluate the key parameters that may affect the natural frequencies and the corresponding mode shapes for this type of bridge. These parameters are end-diaphragm thickness, number of cross-bracings, aspect ratio, span-to-depth ratio, degree of curvature, number of cells, and span-to-span ratio. The effect of cracking of the concrete deck slab in the vicinity of interior supports is also investigated. Results obtained from tests on a 1/12 scale two-span continuous curved composite three-cell bridge model are used to substantiate the analytical modelling. Based on the data generated from the parametric study, empirical formulas for the dominant frequency are deduced. An illustrated design example is presented. A study is also conducted to determine the dynamic deflections caused by a moving truck over the bridge with a view to improve human discomfort and perception to vibration.Key words: box girder, bridges, cellular, curved, composite, continuous, dynamic analysis, experimental, finite-element.
Review of A23.3-94 simplified method of shear design and comparison with results using shear friction
Authors: Loov Robert E
Published: April 2011

A review of the so-called simplified method of shear design described in CSA A23.3-94 "Design of concrete structures" shows that the method is not simple. The designer is required to check numerous equations and limits. The resulting relation between stirrup spacing and shear strength is found to be an extremely complex line resulting from the intersection of seven separate surfaces. A shear friction model has been developed which seems to predict the shear strength of beams rather well. Stirrups and longitudinal reinforcement provide a clamping force thereby increasing the friction force which can be transferred across a crack along a potential failure plane. This model is based on the shear strength after cracking so that no diagonal tension strength is included. The shear friction model has been used as the basis for determining approximate equations for maximum stirrup spacing. A comparison of these approximate shear friction predictions with those using the simplified method indicates a high degree of correlation but many important differences. It seems that shear design can be clarified as well as simplified by adoption of the shear friction approach.Key words: reinforced concrete, shear, shear friction, shear tests, stirrup spacing.
Analysis and deflections of reinforced concrete flat slabs
Authors: Sherif Alaa G , Dilger Walter H
Published: April 2011

The results of a test on a full-scale 5 m continuous slab are used to study the methods of analysis and calculation of deflection of reinforced concrete flat slabs. The most commonly used methods for the analysis of flat slabs, namely the equivalent frame method, the prismatic member method, the direct design method, and the finite element method, are critically compared using the results of the slab tested. Based on the comparison with the unbalanced column moments in the test, improvements for the prismatic member method are suggested. For the deflection calculations of cracked reinforced concrete flexural members, three methods are investigated: the effective moment of inertia approach, the mean curvature approach, and the bilinear method given in the CEB manual for deflections. To calculate the deflections of flat slabs as column and field strip deflections, new coefficients for distributing the bending moments between the column and middle strips are proposed.Key words: analysis, deflection, flat concrete slab, test.
Drawdown curve and incipient aeration for chute flow
Authors: Hager Willi H , Blaser Frank
Published: April 2011

Turbulent rough flows in spillway chutes are considered in the first part. The drawdown curve is demonstrated to be identical with those of flows in the turbulent smooth regime. It is further shown that all drawdown curves can be expressed with a normalized streamwise coordinate that involves the bottom slope and the uniform and critical flow depths. An explicit solution is presented. The computational results are verified with model observations. Also, previous derivations are generalized and a universal drawdown curve for chute flow is introduced. The results are readily applicable for design. In the second part of this paper, incipient aeration on a spillway chute is investigated, based on the data of Bauer for the boundary-layer thickness. Predictions for the flow depth and location of incipient aeration are in agreement with observations. The effects of bottom slope and relative roughness are demonstrated to be comparably small, whereas the critical depth has a major influence on both flow depth and location of incipient aeration. Typical examples illustrate the computational procedure.Key words: aeration, chute, drawdown, spillway, supercritical flow.
Single-angle compression members welded by one leg to a gusset plate. I. Experimental study
Authors: Temple Murray C , Sakla Sherief SS
Published: April 2011

Single-angle compression members are structural elements that are very difficult to analyze and design. These members are usually attached to other members by one leg only. Thus the load is applied eccentrically. To further complicate the problem the principal axes of the angle do not coincide with the axis of the frame of which the angle is a part. Although it is known that the end conditions affect the load-carrying capacity of these members, procedures have not been developed to account for this. The main objective of this research is to obtain a better understanding of the behaviour and load-carrying capacity of single-angle compression members welded by one leg to a gusset plate fixed to a rigid support. The effects of the gusset plate width, thickness, and the unconnected length were studied. It was determined that the finite element method can be used, with a reasonable degree of accuracy, to predict the behaviour and load-carrying capacity of these members. It was found that the thickness and width of the gusset plate significantly affect the load-carrying capacity, but the unconnected length has only a minor effect.Key words: angles, buckling, building (codes), columns (structural), compressive resistance, design, gusset plates.
A numerical study of thermal ice loads on structures
Authors: Azarnejad A , Hrudey T M
Published: April 2011

A numerical model is presented for the prediction of the three-dimensional stress field in an ice sheet due to temperature changes, as a function of time, under a variety of conditions. The model relies on two separate computer programs for the thermal and mechanical aspects of the problem. The thermal program uses the finite difference method to calculate the temperature distribution through the thickness of the ice cover under a variety of meteorological input conditions. The mechanical part of the analysis is conducted using the finite element method. A degenerate shell element is used, which is capable of modeling both bending and membrane behaviors of the ice cover. Relevant features of the finite element model include variable temperature and properties through the thickness, an elastic foundation representation of the underlying water, nonlinear constitutive behavior of the ice, temperature-dependent mechanical properties, flexibility of resisting structures, and boundary conditions representing a variety of shoreline types. Results are presented from simulations conducted during verification of the model. Included are simulations of uniaxial and biaxial laboratory tests on the thermal expansion of ice as well as three thermal events for which field data were available. Conclusions are presented concerning the analytical prediction of thermal ice forces.Key words: ice loads, thermal loads, ice mechanics, hydraulic structures, dams.
Testing in isolation of transverse confining systems for steel-free deck slabs
Authors: Bakht Baidar , Aly Ahmed
Published: April 2011

The provisions of the forthcoming Canadian Highway Bridge Design Code are noted for the design of the external transverse confining system for steel-free deck slabs of girder bridges; according to these provisions, the transverse straps comprising the confining system are required to have a certain minimum axial stiffness, and their connection strength with the deck slab is also specified. The axial stiffness of the straps and their connection strength were studied with the help of pull-out tests on mirror-image models of isolated segments of the deck slab and four different types of strap systems. Three of the tested systems were found to be adequate, and the fourth was considered inadequate because of insufficient connection strength.Key words: arching in slabs, cruciform strap, deck slab, girder bridge, partially studded strap, punching shear, steel-free deck slab, transverse confinement.
Sight distance red zones on combined horizontal and sag vertical curves
Authors: Hassan Yasser , Easa Said M
Published: April 2011

Coordination of highway horizontal and vertical alignments is based on subjective guidelines in current standards. This paper presents a quantitative analysis of coordinating horizontal and sag vertical curves that are designed using two-dimensional standards. The locations where a horizontal curve should not be positioned relative to a sag vertical curve (called red zones) are identified. In the red zone, the available sight distance (computed using three-dimensional models) is less than the required sight distance. Two types of red zones, based on stopping sight distance (SSD) and preview sight distance (PVSD), are examined. The SSD red zone corresponds to the locations where an overlap between a horizontal curve and a sag vertical curve should be avoided because the three-dimensional sight distance will be less than the required SSD. The PVSD red zone corresponds to the locations where a horizontal curve should not start because drivers will not be able to perceive it and safely react to it. The SSD red zones exist for practical highway alignment parameters, and therefore designers should check the alignments for potential SSD red zones. The range of SSD red zones was found to depend on the different alignment parameters, especially the superelevation rate. On the other hand, the results showed that the PVSD red zones exist only for large values of the required PVSD, and therefore this type of red zones is not critical. This paper should be of particular interest to the highway designers and professionals concerned with highway safety.Key words: sight distance, red zone, combined alignment.
Gold Creek dam and its unusual waste waterway (1890-1997): design, operation, and maintenance
Authors: Chanson Hubert , Whitmore R L
Published: April 2011

Completed in 1885, the Gold Creek dam is an earthen dam located on the outskirts of Brisbane, Australia. The spillway system was refurbished three times, each time to increase the maximum overflow capacity. In 1890, a concrete stepped waterway was built to replace the damaged unlined-rock channel. This staircase chute is an unique structure: it is the first large man-made waste waterway built in Queensland, it is the only stepped weir built in Queensland before 1900, and it is, so far as the writers are aware, the first concrete-stepped spillway built for a large dam. The characteristics of the dam and its unusual stepped spillway are reviewed in a historical context. The design is compared with contemporary structures and present knowledge in stepped spillway design. The authors believe that the Queensland engineers gained expertise from overseas and within Australia for the stepped spillway design. However, the selection of concrete for the step construction was made by the local engineers and the reasons behind the decision are not yet understood.Key words: spillway design, engineering heritage, concrete construction, stepped weir, spillway operation, spillway refurbishment, 19th century structure.
Construction site dewatering analysis using a special purpose simulation-based framework
Authors: Hajjar Dany , AbouRizk Simaan , Xu Jianfei
Published: April 2011

Computer simulation has been successfully implemented in the area of construction management. However, this success has generally been limited to the academic arena with the industry lagging far behind. This failure is partly due to the inherent complexity of general simulators and their inability to abstract the underlying modeling fundamentals. Special purpose simulation (SPS) is a framework developed to address the stated drawbacks by focusing on the needs of the construction practitioner. The idea is to build modeling environments tailored to the specific requirements of a given industry domain. This paper presents the development and implementation of a construction dewatering analysis framework based on the ideas of SPS. Object-oriented design and graphical user interfaces are used in the development of an abstraction layer between a steady state hydrological model and the user. The integration capability of the framework are then presented by constructing an optimization module and linking it to the main modeling environment. A case study is provided to demonstrate the usefulness, intuitiveness, and validity of the framework.Key words: simulation, special purpose simulation, construction dewatering, optimization, computer applications.
Impact des erreurs de prédiction de la pluie sur le contrôle en temps réel des réseaux d'égouts unitaires
Authors: Bilodeau Andrée , Mailhot Alain , Villeneuve Jean-Pierre
Published: April 2011

This paper presents results of a study the goal of which is to evaluate the impact of rainfall forecast errors on real time control (RTC) of combined sewers in the Québec Urban Community (Q.U.C.). Firstly, we analyzed the impact of different levels of uncertainty on the probability to generate overloads in combined sewers and on the optimal overflow volume. The effects of the spatial distribution of errors on overloads and on overflow volumes have also been studied. Secondly, we modified the system management decision criteria in order to reduce the overload probability and to avoid possible backflows. This modification consisted of reducing the maximum allowable flow in the pipes of the sewer network. The results obtained showed that despite the negative impacts of forecast errors on overloads, this simple method preserves the efficiency of predictive integrated management. This ensures a safety margin on the possible backflows due to meteorological forecast errors.Key words: overflow, real time, control, combined sewers, forecast, errors, rain, overloads, backflows.
Performance of high strength concrete-filled steel columns exposed to fire
Authors: Kodur VKR
Published: April 2011

Results from an experimental program on the behaviour of high strength concrete-filled steel hollow structural section (HSS) columns will be presented for three types of concrete filling. A comparison will be made of the fire-resistance performance of HSS columns filled with normal strength concrete, high strength concrete, and steel-fibre-reinforced high strength concrete. The various factors that influence the structural behaviour of high strength concrete-filled HSS columns under fire conditions are discussed. It is demonstrated that, in many cases, addition of steel fibres into high strength concrete improves the fire resistance and offers an economical solution for fire-safe construction.Key words: high strength concrete, steel columns, fire-resistance design, high-temperature behaviour, concrete-filled steel columns.
Distribution of volatile organic contaminants between water and air
Authors: Peng Jian
Published: April 2011

Exchange of synthetic organic contaminants across the air-water interface is a significant process affecting the fate of the contaminants released into the environment. Benzene, toluene, trichloroethylene, and tetrachloroethylene were selected as typical contaminants in this study. The equilibrium distribution of the selected volatile organic compounds between air and water was simulated in the laboratory at the University of Saskatchewan. A gas chromatograph headspace auto sampler system was used to analyze the chemical concentrations. The effect of salinity on the equilibrium distribution of selected organic contaminants between water and air was studied. Concentrations of sodium chloride from 100 to 1000 mol/m3 were used to simulate various levels of salinity in water at a temperature of 20°C. Typical seawater was simulated with 3.5% sodium chloride and tested at temperatures from 15°C to 45°C. A modified van't Hoff expression was developed by incorporating a salting-out coefficient to predict the effect of temperature and salinity on the equilibrium distribution. The parameters of the modified van't Hoff model were determined by using the experimental results for selected organic contaminants.Key words: water pollution, volatile organic contaminants, distribution, salinity.
Phosphorus removal in agricultural wastewater by a recently constructed wetland
Authors: Sérodes Jean B , Normand David
Published: April 2011

Constructed wetlands are gaining increased attention for treatment of various types of agricultural-source pollution. A four-cell surface-flow wetland was constructed during the 1996 spring season and was used immediately the same summer and fall. While the general purpose of the project is to monitor the efficiency of the system under various operating conditions, the specific interest of this first year of operation was to study its efficiency in reducing phosphorus during the first weeks of use. With inflow concentrations around 20 mg/L, the removal of phosphorus was limited to 50% for ortho-P and 63% for total P during the first summer of use. Important horizontal and vertical gradients in P concentrations were also noted, and the initial choice of a convenient soil was questioned.Key words: constructed wetland, phosphorus.
Performance of pavement crack sealants in cold urban conditions
Authors: Masson J -F , Collins P , Légaré P -P
Published: April 2011

Twelve bituminous hot-pour crack sealants were evaluated over four years in temperatures ranging from -40°C to +40°C. Each sealant was evaluated over 900 linear meters of transverse and longitudinal routs of 12 × 12 mm2, 19 × 19 mm2, and 40 × 10 mm2 (width × depth). Results show that sealant source, rout size, and rout orientation affected sealant performance, i.e., debonding and pull-out levels. Debonding levels were 0-50% and pull-out levels 0-30%. Sealant failure was proportional to rout width; it was lowest in 12 mm wide routs and highest in 40 mm wide routs. This result is attributed to the proportional exposure of sealants to slow moving traffic. The increase of sealant failure over time was also found to be nonlinear. Three stages were identified in the failure-time plot. In stage 1, failure is rapid; in stage 2, it plateaus; and in stage 3, it increases again. Failure in stage 1 is thought to be related mainly to a weak sealant - asphalt concrete interface, whereas that in stage 3 is thought to be related to sealant weathering and stiffening. It was also found that standard test results correlate poorly with field performance.Key words: pavement, crack sealing, sealant, performance, cold weather, failure.
Highway construction and maintenance costs
Authors: Christian John , Newton Linda
Published: April 2011

This paper gives details of the results of research on maintenance management practices and expenditures on road infrastructure in the province of New Brunswick during the period 1965-1994. An analysis of historic levels of spending on road maintenance, rehabilitation and new construction; current maintenance management practice; and the source and allocation of funds indicated three trends: (i) routine and preventive maintenance funding has steadily decreased over the past 30 years while traffic and vehicle registrations have increased; (ii) maintenance expenditures are not keeping pace with system needs; and (iii) there is a need for a review of traditional construction and maintenance management practices. Three cost prediction models were developed to determine an accurate cost for road maintenance. Based on the models and the management review, it was concluded that maintenance funding needs to be increased by 25% in conjunction with the implementation of a comprehensive maintenance management system, if the Department of Transportation is to adequately meet the current and future needs of the existing road network.Key words: road maintenance, maintenance management, road construction.
Seismic response of two-storey buildings with concentrically braced steel frames
Authors: Medhekar M S , Kennedy DJL
Published: April 2011

The seismic performance of two-storey steel buildings with concentrically braced frames as the lateral load resisting system is evaluated. The buildings are designed in accordance with the National Building Code of Canada (1995) and CSA Standard S16.1-94 for five seismic zones in western Canada. Only frames designed with a force modification factor of 1.5 are considered. Analytical models of the buildings are developed, which consider the nonlinear seismic behaviour of the concentrically braced frame, the shear strength of the roof diaphragm, and the stiffness and strength contributions of the nonstructural partitions. The seismic response is estimated with nonlinear static and dynamic time history analyses. Roof diaphragm flexibility does not influence the dynamic behaviour significantly. The distribution of lateral forces from response spectrum analysis agrees well with that specified. Current design procedures provide reasonable estimates of the lateral drift in low and moderate seismic zones. Brace ductility demands are reasonable and may be limited due to the contributions of nonstructural partitions. However, in moderate and high seismic zones, the connections, beams, columns, and roof diaphragm are overloaded. The capacity design procedure is recommended to provide adequate resistance to the overloaded components.Key words: analyses, capacity design, concentrically braced frame, diaphragm, dynamic, earthquake, low-rise, nonlinear, seismic design, steel.
Évolution du risque hydrologique sur la rivière Châteauguay
Authors: Awadallah A G , Rousselle J , Leconte R
Published: April 2011

The 1990s have been marked by several hydro-meteorological extremes, to such an extent that it can be inquired if the riverside residents are exposed to a risk, which is increasing with time. This perception of an increasing risk could be due to a change in the frequency or intensity of the events, to a change in the exploitation of resources, or even to the media coverage of catastrophes. This article aims to study the progressive modification of the likelihood of flood event occurrence (maximum flow) in the Châteauguay River basin, based on available hydrometric data. The data has been studied, using homogeneity and statistical control tests, to examine the possibility of merging the data of two stations, in order to obtain a series, which is sufficiently long to reveal the evolution of hydrological risk and to study the change in the estimation of the 100-year return flood. The merged series was then divided into subsets on which frequency analyses were performed using the linear moments method. Estimations of the 100-year return flood from different samples did not present significant differences. The bootstrap technique was then used in order to quantify the uncertainty due to sampling. The results of the analysis show the absence of a general upward or downward trend of the hydrological risk on the Châteauguay River.Key words: hydrological risk, Châteauguay River, linear moments, bootstrap, statistical hydrology.[Journal translation]
Gauss-legendre quadrature estimates of discharge for the performance testing of low-head hydroelectric turbines
Authors: Doering John C , Gawne Kevin D
Published: April 2011

The performance testing of low-head hydroelectric turbines is necessary for the efficient and economic operation of a generating station. Of the information required for performance testing, discharge is the most difficult to measure accurately. The velocity-area method is typically used to measure discharge through a low-head plant. Herein the combination of acoustic technology and Gauss-Legendre quadrature (GLq) integration is investigated as an alternative method of measuring discharge. Physical hydraulic modeling was performed to examine the accuracy of discharge estimates associated with different GLq sampling strategies. Data obtained from laboratory testing indicate that the accuracy of estimating discharge increases with the number of GLq levels used. Discharge errors of less than 1% were observed (for undisturbed flow conditions) when 8 or more GLq levels were used.Key words: turbine, performance testing, acoustic discharge measurement, Gauss-Legendre quadrature integration.
Evaluation of the level of seismic protection afforded to reinforced concrete shear wall systems
Authors: Stonehouse Brian , Heidebrecht Arthur C , Kianoush M Reza
Published: April 2011

This paper presents the results of an investigation into the seismic level of protection afforded to reinforced concrete shear wall systems. The vulnerability and damage potential of a 30-storey building consisting of a coupled shear wall as well as noncoupled shear walls as lateral force resisting systems is evaluated. The structure, which is similar to an existing building designed and constructed in Vancouver, is designed in accordance with the 1995 National Building Code of Canada and detailed using the provisions of CAN3-A23.3-M94 (1994). Elastic analysis is performed using both two-dimensional and three-dimensional shell element models for lateral loading with and without the effects of torsion. Element design specifications are used to create moment curvature envelopes to describe the members (beam and wall) deformation characteristics. These characteristics are incorporated into the nonlinear pushover analysis and dynamic inelastic time history analysis. The level of protection investigation illustrates that the coupled and noncoupled shear wall systems exhibit excellent performance following excitations of two and three times the design level earthquake. Maximum interstorey drift and element damage levels are within the acceptable limits for life-safe performance.Key words: seismic, reinforced concrete, shear walls, coupling beams, performance, inelastic, dynamic, design.
Punching behaviour of composite bridge decks transversely prestressed with carbon fibre reinforced polymer tendons
Authors: Marshe Sylvanus , Green Mark F
Published: April 2011

Composite bridge decks under concentrated wheel loading develop compressive membrane action that tends to increase significantly the strength of the deck slab. Transverse prestressing of the deck slab can improve the compressive membrane action and allow a reduction in the slab thickness. With a reduced thickness, however, durability is a concern with steel prestressing tendons. By using fibre reinforced polymer prestressing tendons, the durability of the bridge deck slab can be improved. This paper describes an experimental investigation to study the punching behaviour of composite bridge decks transversely prestressed with carbon fibre reinforced polymer (CFRP) tendons. Six panels of a 1/4.04-scale model of a simply supported composite bridge deck are tested under a static concentrated wheel loading. The results are compared to those from a previous similar study using steel prestressing tendons. It is shown that it is feasible to use CFRP tendons to transversely prestress composite bridge decks, and that the CFRP prestressed bridge deck shows better overall structural performance than the steel prestressed deck. The lack of plasticity of the CFRP tendons is not a concern in this application.Key words: composite bridge deck, concrete, compressive membrane action, punching shear, prestressing, advanced composite material (ACM), fibre reinforced polymer (FRP).
Microscopic simulation of lane changing behaviour at freeway weaving sections
Authors: Al-Kaisy A F , Stewart J A , Aerde M Van
Published: April 2011

Microscopic traffic simulation models are being increasingly used to evaluate Intelligent Transportation Systems (ITS) strategies and to complement empirical data in developing new analytical procedures and methodologies. Lane changing rules are an essential element of any microscopic traffic simulation model. While most of these rules are based on theories and hypotheses, to date no attempt has been made to investigate the consistency of lane changing behaviour from microscopic simulation with empirical observations. The research presented in this paper examined this consistency at freeway weaving areas using empirical data. These data were collected in the late 1980s at several major freeway weaving sections in the State of California. The microscopic traffic simulation model INTEGRATION was used to perform simulation experiments in this research. Vehicle distributions, both total and by type of movement, were used as measures to investigate the lane changing activity that took place at these freeway areas. This examination revealed significant agreement between patterns of lane changing behaviour as observed in the field and as reproduced by microscopic simulation. Most quantitative discrepancies were shown to be a function of user-specified input data or due to some inherent limitations in the empirical data.Key words: simulation, lane changing, weaving, freeways.
Mechanism of shear transfer in a reinforced concrete beam
Authors: Olonisakin Akin A , Alexander Scott DB
Published: April 2011

This paper presents an analysis of the results of five tests conducted on four reinforced concrete beams. The tests were performed principally to investigate the mechanics of internal shear transfer in a transversely loaded concrete beam with no shear reinforcement. Test specimens consisted of simply supported wide beams with steel flexural reinforcement. The reinforcement for two of the beams was epoxy coated. The shear span to depth ratios were 2.93, 3.32, and 3.81. Measured strains on the reinforcement were used to divide the total shear into its beam and arching action components. In all tests, beam and arching action shear transfer mechanisms were found to coexist. Apart from that with the longest span, all tests ended with rupture of the concrete along a diagonal failure surface. It is concluded that shear failure may be caused by a shift in the internal mechanics of shear transfer from beam action to arching action. Because this shift may be initiated by the yielding of reinforcement, it can be associated with the formation of a plastic hinge. There was no observed effect on the mechanics of shear transfer that could be attributed to epoxy coating of the reinforcement.Key words: arching action, beam action, one-way shear, shear transfer, reinforced concrete beam, bond forces, bar force gradient.
Modeling subsoil drainage systems for urban roadways
Authors: Cyr Robert Y , Chiasson Paul
Published: April 2011

Water infiltration and seepage in a roadway infrastructure is modeled from a cross section design of a residential street used by the City of Moncton (Department of Engineering). Field hydraulic conductivity measurements necessary for the modeling are also presented. Benefits of having a subsoil drainage systems (perforated drainage pipe and drainage mat) are well demonstrated. Some drainage problems caused by insufficient hydraulic conductivity, segregation, and limits on gradation curves for the gravel base foundation, as specified by the City of Moncton, are also discussed.Key words: roadway design, subsoil drainage, seepage modeling, field permeability measurements.
Minimisation de la sensibilité à l'eau de composites cimentaires argile-schistes-bois
Authors: Ledhem A , Dheilly R M , Benmalek M , Queneudec M
Published: April 2011

The use of clay and wood waste in construction materials points out to a sensitivity to water, which is susceptible to reduce their durability. This work has first been interested in the influence of different constituents on the extreme dimensional variations (EDV) of such cementing composites. A formulation allowing the conciliation of environmental imperatives, interesting mechanical and thermal characteristics, and low density has been proposed. However, the EDVs remain above the required objective. In order to reach this value, different treatments have been examined. The addition of alkali-resistant fiberglass in the matrix did not lead to satisfactory results. Not only is the reduction of the EDVs insufficient for reasonable proportions of fibers, but this treatment also increases the proportion of absorbed water in presence of liquid water. Taken separately, both types of treatments used for wood particles - neutralization with hydraulic binders and extraction with boiling water of hydro-soluble compounds - also do not allow a sufficient reduction of EDVs. However, the combination of these two treatments allows the achievement of EDV [Formula: see text] 1 mm/m. Such a treatment improves the mechanical resistance without significantly altering the thermal performances.Key words: wood concrete, extreme dimensional variation, fiberglass, neutralization, hydrolysis.[Journal translation]