bluuebunny/crossref_metadata_2025 huggingface dataset:
La simulation assistée par ordinateur dans le contrôle et l'utilisation optimale des ressources hydriques
Authors: Serhir N. , Marche C.
Published: January 2010

Simulators are gradually becoming popular in hydraulic engineering. They allow real-time control of hydroelectric projects, help operators optimize facilities, and are excellent for training technical staff. This paper shows how to constitute a specialized simulator for each water resource system using a model builder and a set of site data. The model builder is based on digitization by finite element method. Resolution without linking is applied, allowing use of time-step variables. Each simulator constituted can operate in controlled or uncontrolled mode. An example illustrates the search for optimum generation mode for a network composed of three power plants. Key words: simulator, hydroelectricity, finite element method. [Journal translation]
Parameter optimization in modelling unsteady compound channel flows
Authors: Abida Habib , Townsend Ronald D.
Published: January 2010

Optimization methods are used to estimate data for routing floods through open compound channels (main channels with flood plain zones). These data include the irregular channel section geometry and the varying boundary roughness. Differences between simulated and observed stages and discharges are minimized using three optimization algorithms: Powell's method, Rosenbrock's algorithm, and the Nelder and Meade simplex method. Powells' method performed poorly; however, both the Rosenbrock and simplex methods yielded good results. The estimated data using the Rosenbrock and simplex methods were used to route different flood events observed in a laboratory channel. Simulated peak stages and discharges were in good agreement with those estimated using actual routing data. Key words: compound channel, flood routing, lateral momentum transfer, optimization, unsteady flow.
Finite element modeling of surge propagation and an application to the Hay River, N.W.T.
Authors: Hicks F. E. , Steffler P. M. , Gerard R.
Published: January 2010

This paper describes the application of the characteristic-dissipative-Galerkin method to steady and unsteady open channel flow problems. The robust performance of this new finite element scheme is demonstrated in modeling the propagation of ice jam release surges over a 500 km reach of the Hay River in Alberta and Northwest Territories. This demonstration includes the automatic determination of steady flow profiles through supercritical–subcritical transitions, establishing the initial conditions for the unsteady flow analyses. The ice jam releases create a dambreak type of problem which begins as a very dynamic situation then develops into an essentially kinematic wave problem as the disturbance propagated downstream. The characteristic-dissipative-Galerkin scheme provided stable solutions not only for the extremes of dynamic and kinematic wave conditions, but also through the transition between the two. Key words: open channel flow, finite element method, dam break, surge propagation.
Thunder Creek mercury control
Authors: Haug M. D. , Forgie D. J. L. , Zitta R. , Bews B. E.
Published: January 2010

In 1978, mercury contamination was discovered in sediments near the confluence of Thunder Creek and the Moose Jaw River, in the City of Moose Jaw, Saskatchewan, Canada. A detailed investigation revealed up to 95 mg/kg of mercury in the floodplain sediments. This contamination was primarily concentrated along the north bank of Thunder Creek and in the adjacent creek sediments. The extent of the contamination indicated that it had not occurred recently, and that total removal of the mercury would be difficult and costly. Thus, a mercury control plan was initiated to remove or effectively contain 95% of the contamination. Contaminated sediments were excavated by dragline from the floodplain and placed on top of mercury contaminated surface sediment along the north bank of Thunder Creek. A soil backfill slurry trench cutoff wall was constructed along the creek through permeable soils and keyed into a low permeability clay shale to isolate the contaminated sediments. The contaminated sediments were also isolated by the construction of an interceptor ditch to direct water around the containment area past the cutoff wall. The contaminated sediments were compacted and covered with lime-modified clay and a topsoil cover which was seeded with grass. Monitoring of water and sediments along Thunder Creek and the Moose Jaw River since implementation of these control measures has shown a significant reduction in mercury levels, indicating that the control system is meeting its objectives. Key words: mercury, environment, contamination, mitigative measures, slurry trench cutoff, interceptor drains, monitoring.
Concrete constitutive models for nonlinear seismic analysis of gravity dams — state-of-the-art
Authors: Bhattacharjee Sudip S. , Léger Pierre
Published: January 2010

The seismic safety of concrete dams is a matter of serious concern around the world. During severe ground motions, the dams are likely to experience cracking due to low tensile resistance of concrete. Several analytical methods have been proposed in the literature for finite element crack propagation analysis of concrete structures. Due to lack of consistent results, and virtually impossible verification because of limited field experience in seismic cracking of concrete dams, the choice of a reliable constitutive model has become a complex task. A review of concrete constitutive models for nonlinear seismic analysis of gravity dams is presented herein. The relative merits of the proposed models have been critically examined. Comparing the theoretical soundness, and the advantages and inconveniences of the different analytical procedures, the nonlinear fracture mechanics model applied with a smeared crack analysis technique appears to be very promising. The present state of knowledge on material fracture parameters under transient conditions has been found to be limited. Review of the past finite element seismic fracture analyses of concrete gravity dams reveals that reliable numerical models for safety evaluation of the structures during severe ground motions have not yet been satisfactorily developed. Key words: gravity dams, constitutive models, fracture mechanics, seismic response, nonlinear analysis, finite element, crack propagation.
Seismic analysis of short-period structures subjected to the 1988 Saguenay earthquake
Authors: Léger Pierre , Romano Angelo
Published: January 2010

This paper presents elastic and inelastic response spectra of strong motion accelerograms recorded during the 1988 Saguenay earthquake. Comparisons are made with the National Building Code of Canada (NBC) 1990 lateral forces requirements for the seismic resistant design of short-period structures. The use of a period-dependent force modification factor is proposed to take advantage of the energy dissipation capacity of short-period structures on a more rational basis. The seismic response of a typical low-rise steel building designed according to the NBC 1990 and CAN3-S16.1-M89 is then investigated. It is shown that to obtain a realistic picture of the ductility demand of low-rise buildings, the structural overstrength, that is, the supplied strength in excess of the seismic design base shear, should be explicitly considered in the design process. Key words: seismic design, earthquake, low-rise structures, code.
Effect of weak foundation on the seismic response of core wall type buildings
Authors: Filiatrault A. , Anderson D. L. , DeVall R. H.
Published: January 2010

This paper investigates the seismic behaviour of a typical wall-type reinforced concrete building with a footing that is unable to develop the flexural wall capacity. Nonlinear dynamic analysis is used to determine the response of the structure under historical earthquakes representing design conditions for a seismic zone 4 in Canada. The analysis incorporates the nonlinear behaviour of the core, footing and soil, and also the uplift of the footing from the soil. Three different structural models are considered: (i) the core on a rigid foundation, (ii) the core on a flexible (rocking) foundation, and (iii) the core on a flexible foundation with the two lower levels connected to a parking structure. The results show that the weak footing does not have a great influence on the performance of the building considered. The parking structure and the rocking foundation cause a reversal and increase of the shear forces in the lower storeys. Also, the reduction of bending moments due to the core yielding is not proportional to the reduction of shear forces. This result suggests a need for different force modification factors for shear and bending. Key words: dynamics, earthquakes, reinforced concrete, building codes, foundations, footings.
Evaluation of the length of a wide channel subject to seepage and evaporation losses
Authors: Hathoot Helmi M. , Al-Amoud Ahmed I. , Mohammad Fawzi S.
Published: January 2010

This paper addresses the analysis of a wide channel subject to seepage and evaporation losses, the channel being excavated in a permeable soil underlain by a highly permeable aquifer of low piezometric head. The authors present two equations, one for estimating the channel discharge at a general channel section and one for estimating the total length of the channel. The channel length equation is modified to calculate the hydraulic conductivity of the top soil. Finally, two numerical examples are given to show how to use the equations. Key words: channel length, wide channel, seepage, evaporation.
Structural damage due to the April 22, 1991, Costa Rican earthquake
Authors: Mitchell Denis , Tinawi René
Published: January 2010

Examples of structural damage, investigated during a site visit following the April 22, 1991, Costa Rican earthquake, are presented. Some aspects of the seismic zoning and the seismicity of Costa Rica are discussed. Severe damage to schools, residential dwellings, a hospital, hotels, and roadways is reported. Damage and collapse of bridges due to severe ground movements, pile failures, failure of restrainers, loss of support, and embankment failures are illustrated. Damage to industrial facilities, including examples of failures of cylindrical storage tanks, due to severe sloshing and buckling is highlighted. Key words: seismic design, earthquake, Costa Rica, buildings, bridges, codes, industrial facilities, storage tanks.
High frequency hydrodynamic coefficients of vertical cylinders
Authors: Isaacson Michael , Mathai Thomas
Published: January 2010

Alternative methods of calculating high frequency added masses and damping coefficients of vertical cylinders of arbitrary section are described. Damping coefficients are calculated by a short-wave approximation relating to the local form of waves generated by the oscillating structure. As an alternative, they are also obtained from the exciting forces of the related scattering problem, with these forces obtained by a geometrical optics approximation. Added masses are obtained by discarding the propagating mode and using only the evanescent modes which are free of irregular frequencies. They are also obtained by an application of the Kramers–Kronig relations, which require the infinite frequency added masses and the damping coefficients at all frequencies. Numerical results obtained by the various methods are compared with corresponding analytical results for vertical circular and elliptic cylinders. The practical application of the proposed approach is indicated. Key words: added mass, cylinders, damping, hydrodynamics, ocean engineering, offshore structures, waves.
Seismic performance of reinforced concrete ductile moment-resisting frame buildings located in different seismic regions
Authors: Zhu T. J. , Tso W. K. , Heidebrecht A. C.
Published: January 2010

Seismic areas in Canada are classified into three categories for three different combinations of acceleration and velocity seismic zones (Za < Zv, Za = Zv, and Za > Zv), and ground motions in different zonal combination areas are expected to have different frequency characteristics. The National Building Code of Canada specifies different levels of seismic design base shear for short-period buildings located in areas with different zonal combinations. The specification of seismic design base shear for long-period buildings is directly tied to zonal velocity, irrespective of seismic zonal combination. This paper evaluates the seismic performance of both high-rise long-period and low rise short-period reinforced concrete ductile moment-resisting frame buildings located in seismic regions having Za < Zv, Za = Zv, and Za > Zv. Two frame buildings have 10 and 18 storeys were used as structural models for high-rise buildings, while a set of four-storey buildings were used to represent low-rise buildings. All buildings were designed to the current Canadian seismic provisions and concrete material code. Three groups of earthquake records were selected as representative ground motions in the three zonal combination regions. The inelastic responses of the designed buildings to the three groups of ground motions were analyzed statistically. The results indicate that the distribution of inelastic deformations is significantly different for high-rise frame buildings situated in seismic regions with Za < Zv, Za = Zv, and Za > Zv. Inelastic deformation is concentrated in the lower storeys for high-rise buildings located in Za < Zv areas, whereas significant inelastic deformation can develop in the upper storeys for high-rise buildings situated in Za > Zv regions. The use of three different levels of seismic design base shear for short-period structures improves the consistency of ductility demands on low-rise buildings situated in the three different zonal combination regions. Despite the use of appropriate design base shears for different seismic regions, the ductility demands for these low-rise buildings are relatively high. To avoid excessive ductility demands, it is suggested that the seismic strengths for low-rise short-period buildings should not be significantly reduced from their elastic design base shears. Key words: earthquake, ground motion, seismic, design, reinforced concrete, frame buildings, beams, columns, ductility.
Wind-induced torsional loads on buildings
Authors: Lythe G. R. , Surry D.
Published: January 2010

This paper examines the mean and peak torsional wind loads on tall buildings using two data bases of torsion measured experimentally in wind tunnel tests: the first, a large data base of mean torsional loads; and the second, a smaller data base of peak torsions. Although the mean load constitutes only a part of the total peak load required for design, it provides considerable insight into the aerodynamics of torsion, while improvement in its estimation also improves the estimation of the total peak load, using empirical gust factor methods. Comparisons between experimental results and the corresponding provisions of the 1985 National Building Code of Canada and Commentary indicate that, while the NBCC is a good estimator of mean shear loads, it significantly underestimates the mean torsional loads on tall buildings. The experimental data are further analysed to provide an improved estimation method for both the mean and the peak torsion. For mean torsion, this involves evaluating various definitions of the torsion coefficient and classifying building shapes in order to decrease the variability of the associated coefficients. This process leads to some notion of those shapes susceptible to large torsional loads and the most important building parameters on which to base predictions. This insight, along with the data base of peak torsion, is used to simplify and improve an existing method for estimating peak torsion, which was developed using a smaller data base. Key words: torsion, wind loading, codes, wind tunnel tests, tall buildings.
Spline finite strip analysis of continuous haunched box-girder bridges
Authors: Cheung M. S. , Li Wenchang , Jaeger L. G.
Published: January 2010

In this technical note, a spline finite strip for curved bottom flange of box-girder bridges is developed so that the spline finite strip method is extended to the analysis of continuous haunched box-girder bridges. This method is more capable in dealing with concentrated loads and is more flexible in treating discrete support conditions than the semi-analytical finite strip method. Key words: finite strip, box-girder bridges, spline function, structural analysis, composite.
Durabilité au gel-dégel et résistance à l'écaillage des pavés de béton
Authors: Boisvert Jean , Marchand Jacques , Pigeon Michel , Isabelle Henri L.
Published: January 2010

Tests results described in this paper show that it is quite easy to produce concrete paving blocks with excellent resistance to freezing–thawing cycles in water. Good resistance to frost-associated scaling in the presence of deicing salts is, however, much more difficult to obtain; and the problem is particularly difficult to analyse because two types of tests gave very different results. A freezing test in the presence of a saline solution (ASTM C672) showed positive influence of certain parameters (such as finer material), but freezing tests in a brine bath (ACNOR CAN3 A231.2 M85) did not show influence of any variable. In addition, the high number of compacting voids made it very difficult to interpret measurements of air-void characteristics made by examining ground sections under an optical microscope (ASTM C457). Key words: concrete paving blocks, scaling resistance, deicing salts, freezing–thawing cycles, air-void spacing factor. [Journal translation]
Code provisions for seismic design for concentrically braced steel frames
Authors: Redwood R. G. , Jain A. K.
Published: January 2010

Extensive research into the inelastic seismic response of concentrically braced frames and their components has been carried out in the last two decades. This knowledge has now been incorporated into seismic design practice in several countries, notably the U.S.A., Canada, and New Zealand. In this paper, design specifications from these three countries, which derive largely from the same body of research, are compared. The basic design philosophy for concentrically braced steel frames, loading, and member detailing are examined. It is concluded that, in general, the Canadian specifications are in conformity with the available information and have many similar features to codes of the other countries. Significant differences exist in the classification of braced frames, between interstorey drift requirements, in the treatment of dual structural systems, and to a lesser extent in member detailing requirements. Some features of Canadian codes meriting review are identified. Key words: structural engineering, earthquakes, standards, steel, braced frame, ductility, concentric bracing, dual system.
A microcomputer-based analysis and design of air-supported cylindrical membranes
Authors: Turkkan N. , Srivastava N. K.
Published: January 2010

An approximate, simple, and reliable method of analysis is presented for an air-supported cylindrical membrane structure. Furthermore, to use this method of analysis for design purposes, a brief description of dominant design loads and its formulation as applied to air-supported structures is also given based on design practice and experiments. Incorporating both the method of analysis and the described design loads, a microcomputer-based program, coded in MS Quickbasic, has been developed, which is simple to use and completely user friendly.First, the reliability of the approach is established by comparing it with available published studies on circular cylindrical air-supported structures, based on rigorous modelling and analysis. Then, several illustrative examples are presented for different heights and spans under various loading combinations as per current design practice. Key words: air-supported membrane, cylindrical, finite displacement, microcomputer based, approximate, analysis, design.
Navigation user requirements and emerging technologies for the Canadian transportation sector
Authors: Lachapelle G. , Krakiwsky E. J. , Schwarz K. P. , Chandan A.
Published: January 2010

An analysis of the Canadian transportation sector navigation user requirements and related technologies is presented. The sector is divided into three modes, namely the marine, air, and road modes of transportation. The parameters used to characterize navigation user requirements in transportation are defined; these include accuracy, availability, coverage, reliability, and capacity. Navigation requirements for selected classes of users within each of the three modes are presented. The characteristics of current wide area coverage navigation systems available in Canada are reviewed and compared to user requirements. This is followed by a description of selected enabling technologies considered essential for the full realization and widespread and economical use of emerging navigation systems. As current systems cannot meet all requirements, the potential of emerging navigation systems to provide enhanced performance levels in future is assessed. A review of enabling technologies considered important for the full realization and widespread and cost-effective use of the new systems is presented. Two major classes of emerging systems are then described, namely, autonomous systems such as inertial navigation systems and satellite-based radio-frequency systems such as global positioning systems. An analysis of the suitability of these systems in transportation is then presented. Possible developments required for the emerging navigation systems to be used in an optimal manner in the Canadian transportation sector are outlined in the conclusions. Key words: transportation, assessment, trends, navigation, positioning, location, guidance.
Hydrologic behaviour of a mountainous watershed
Authors: Loukas Athanasios , Quick Michael C.
Published: January 2010

A simplified watershed model has been developed to examine and analyze the high rainfall response of a small, steep, and forested watershed in coastal British Columbia. Hourly data for both rainfall and streamflow are used. Rainfall is measured at five points evenly distributed throughout the watershed. The model is found to perform well and indicates that the hydrologic response of the watershed is reasonably linear, except for intense summer rainstorms under dry soil conditions. The linearity and the rapidity of the watershed response is attributed to the response of the subsurface pipeflow. An analysis of a particular case of soil pipe development shows that the pipeflow system can respond linearly and rapidly to the rainfall input. Key words: watershed modelling, hydrologic response, soil piping.
Schedule compression using the direct stiffness method
Authors: Moselhi Osama
Published: January 2010

This paper presents a new method for critical path (CPM) scheduling that optimizes project duration in order to minimize the project total cost. In addition, the method could be used to produce constrained schedules that accommodate contractual completion dates of projects and their milestones. The proposed method is based on the well-known "direct stiffness method" for structural analysis. The method establishes a complete analogy between the structural analysis problem with imposed support settlement and that of project scheduling with imposed target completion date. The project CPM network is replaced by an equivalent structure. The equivalence conditions are established such that when the equivalent structure is compressed by an imposed displacement equal to the schedule compression, the sum of all member forces represents the additional cost required to achieve such compression. To enable a comparison with the currently used methods, an example application from the literature is analyzed using the proposed method. The results are in close agreement with those obtained using current techniques. In addition, the proposed method has some interesting features: (i) it is flexible, providing a trade-off between required accuracy and computational effort, (ii) it is capable of providing solutions to CPM networks where dynamic programming may not be directly applicable, and (iii) it could be extended to treat other problems including the impact of delays and disruptions on schedule and budget of construction projects. Key words: construction scheduling, time–cost trade-off, project cost optimization, scheduling with constraints, project acceleration.
Computational analysis of creep in ice and frozen soil based on Fish's unified model
Authors: Puswewala U. G. A. , Rajapakse R. K. N. D.
Published: January 2010

The ability of the creep model of Fish to simulate the observed behaviour of ice and frozen soils in multiaxial stress-strain fields is investigated. The generalization of the original uniaxial creep model is made through the use of several assumptions and the multiaxial model is implemented in an iterative, time-incrementing finite element code. Sample creep parameters for the model are evaluated using previously reported uniaxial creep tests on ice and frozen silt. The finite element code is used to demonstrate the ability of the model to predict different stages of creep deformation in frozen media, by re-simulating some uniaxial creep tests on ice. Pressuremeter tests, plate load tests, and laterally loaded rigid cores (piles considered in cross section) in frozen media are simulated to demonstrate the similarity between the global response of ice and frozen soils predicted by the model and the reported experimental findings. Redistribution of stress predicted by the model is also investigated. The model is seen to possess validity in situations of attenuating as well as accelerating creep of ice and frozen soils. Key words: creep, ice, frozen soils, finite elements, structure–frozen media interaction, numerical prediction.
Development of a net pen system for aquaculture farming
Authors: Isaacson Michael , Allyn Norman , Loverich Gary
Published: January 2010

The present paper describes a study carried out to verify a new net pen system which has been developed for aquaculture farming at exposed coastal sites. The structure is based on the use of spar buoys rather than rigid floats to support the net. A prototype structure has been deployed in Juan de Fuca Strait, and a verification of the system is described. This has involved an assessment of the environmental conditions and hydrodynamic loading for the structure, strength and fatigue analyses, and a calibration of wave conditions and mooring line forces with respect to prototype measurements. Overall, the system has been found to perform very well. Recommendations are made for monitoring the prototype system and for carrying out a refined verification of the system based on additional data. Key words: aquaculture, fish farms, hydrodynamics, ocean engineering, offshore structures, waves, wave forces.
A method for the derivation of load effect envelopes based on statistical considerations
Authors: O'Brien Eugene J. , Loov Robert E.
Published: January 2010

A simple method is proposed as a substitute for the usual process of factoring loads, performing a linear elastic analysis, and determining an envelope of the results. The method is based on statistical principles, but only a minimum knowledge of statistics is required for its use. It involves conventional structural analysis followed by some processing of the results which could readily be incorporated into existing computer programs.The practice of performing two-dimensional analyses on parts of three-dimensional structures is possible with the proposed approach. The implications are clarified and the necessary statistical parameters are derived.Deterministically derived design envelopes represent all the extremes of loading that can reasonably be considered. The envelopes found by the new method not only reflect loading variations but also consider their relative probabilities of occurrence so that excursions beyond the envelope are expected to be equally infrequent along the entire length of the structure. Inconsistencies inherent in the conventional approach are highlighted by comparison with the proposed method for a number of examples. Key words: probabilistic, safety, load, imposed load, load effect envelope, building.
Color image analysis for vehicle speed measurement
Authors: Lu Yean-Jye , Yuan Xidong
Published: January 2010

Image analysis for traffic data collection has been studied throughout the world for more than a decade. A survey of existing systems shows that research was focused mainly on the monochrome image analysis and that the field of color image analysis was rarely studied. With the application of color image analysis in mind, this paper proposes a new algorithm for vehicle speed measurement in daytime. The new algorithm consists of four steps: (i) image input, (ii) pixel analysis, (iii) single image analysis, and (iv) image sequence analysis. It has three significant advantages. First, the algorithm can distinguish the shadows caused by moving vehicles outside the detection area from the actual vehicles passing through the area, which is a difficult problem for the monochrome image analysis technique to handle. Second, the algorithm significantly reduces the image data to be processed; thus only a personal computer is required without the addition of any special hardware. The third advantage is the flexible placement of detection spots at any position in the camera's field of view. The accuracy of the algorithm is also discussed. Key words: speed measurement, vehicle detection, image analysis, image processing, traffic control, traffic measurement and road traffic.
Physical and mechanical performance of an innovative glass-fiber-reinforced plastic rod for concrete and grouted anchorages
Authors: Chaallal O. , Benmokrane B.
Published: January 2010

Recently, consideration has been given to replacing conventional steel rebars with glass-fiber-reinforced plastic rods in specific applications such as structures subjected to corrosive or marine environment or where electrical or electro magnetic insulation is required. The paper presents the results of a laboratory investigation including physical and mechanical behaviour of a glass-fiber-reinforced plastic rod. The following tests were conducted: thermal expansion, tension at ambient and high temperatures, compression, flexure, shear, fatigue on bare rods, and pullout of rods embedded in concrete. It was found that the glass-fiber-reinforced plastic rod possessed a higher ultimate tensile stress but much lower modulus of elasticity than steel rebars. The plastic rods withstood fewer cycles than steel bars, particularly at higher levels of stress. The loss of strength at temperatures above 200 °C was found to be considerably higher than steel. The coefficient of longitudinal thermal expansion was similar to that of concrete and steel. In light of the results, examples for concrete structural elements have been illustrated in the paper. Key words: glass-fiber rod, plastic, reinforced concrete, thermal expansion, tension, compression, flexure, shear, high temperature, fatigue, pullout, bond strength, development length, beams, slabs, median barriers.
Numerical stress analysis for fatigue evaluation of welded tubular T-joints
Authors: Nwosu D. I. , Swamidas A. S. J. , Munaswamy K.
Published: January 2010

The stress distribution along the intersection of offshore tubular T-joints under the action of axial and in-plane and out-of-plane (bending) brace loading has been investigated using degenerated shell elements. The ratios of through-thickness membrane to bending stress and bending to total stress have been obtained using a simple linear interpolation between the stresses on the inner and outer surfaces of the tube. The nominal brace stress and the maximum principal stress values have been used for stress concentration factor determination. The influence of thickness and other geometric parameters on the stress distribution along the intersection was investigated in two ways, viz., increasing the chord thickness while maintaining a constant brace thickness, and keeping the chord thickness constant while reducing the brace thickness.Comparison of the shell finite-element results obtained in this study with the semiloof thin-shell finite-element results of the University College, London (UCL), exhibits good agreement. Good agreement exists between the results of this study and the UCL parametric equations for the chord and the brace of the joint, with a maximum difference of about 7% on the braceside around the saddle position. Comparisons between the finite-element results and other known parametric equations for stress concentration factor with different diametral, wall thickness, and chord thickness and ratios also show good agreement. A comparison of the results obtained from the finite-element analysis and the experimental results of the Canadian Cooperative Fatigue Studies Program, carried out at Memorial University of Newfoundland and University of Waterloo, is also made. Key words: stress distribution, finite-element analysis, stress concentration factors, membrane stress, bending stress, tubular T-joints.
Performance of structures during the 1992 Erzincan earthquake
Authors: Saatcioglu Murat , Bruneau Michel
Published: January 2010

A large number of engineered buildings were severely damaged and collapsed during the Richter magnitude 6.8 earth quake that struck Erzincan, Turkey, on March 13, 1992. The building inventory of the city contained structures similar to those built worldwide at the time of their construction. The study of the effects of this earthquake on structures is of particular significance to Canada, since an earthquake of approximately the same magnitude is likely to occur in many parts of the country, where similar structural systems are used. This paper reports on the findings of a 4-day reconnaissance visit conducted by the authors. A brief description of seismological aspects of the earthquake is presented, including characteristics of the ground motion. The emphasis is placed on structural performance during the earth quake, and possible causes of observed structural failures and collapses. Key words: building code, concrete, earthquake, Erzincan, masonry, precast concrete, reinforced concrete, seismic design, structures, structural design, steel, unreinforced masonry.
Household hazardous wastes: options for management
Authors: Boyle Carol , Baetz Brian
Published: January 2010

Household hazardous waste (HHW) disposal contributes significantly to the cost of HHW collection programs. In addition, disposal of HHW can contribute to the toxicity of leachate from landfill, heavy metals in ash from waste incinerators, and heavy metals and toxic organic compounds in composted material and sewage sludge. Other options such as product substitution, waste minimization, reuse, or recycling should be considered to help reduce costs and disposal concerns. An estimate of the volumes and types of HHW accumulated by collection programs, their recycling and reuse options, and treatment and disposal requirements are presented.Recycling, reuse, or disposal of collected wastes depends upon the market for the recycled material, the availability of recycling or disposal facilities, transportation facilities, and the potential to reuse the waste material without treatment. The costs of disposing of HHW are relatively high but can be offset by co-funding from manufacturing associations and local businesses. A disposal fee could also be applied to household hazardous products, thus placing the cost burden on the purchaser.Public education can assist in reducing the volumes of HHW and public pressure is also forcing companies to eliminate hazardous compounds in household products. If effective consumer education continues, the increasing demand for non-hazardous substitutes will significantly reduce the volume of household hazardous products, consequently reducing HHW. Key words: household hazardous waste, waste disposal, waste recycling, waste reuse, waste management.
Laboratory observations of bedforms under directional irregular waves
Authors: Willis D. H. , Davies M. H. , Mogridge G. R.
Published: January 2010

Large-scale laboratory tests of the evolution of bedforms in sand beds, under directional irregular waves, carried out at the National Research Council Canada, are described. Preliminary observations indicate that the directionality of the waves is not an important factor; bedforms remained largely two-dimensional under all but transitional conditions. Incident wave height and period, probably combined as a wave orbital amplitude near the bed, seems to be the most important factor in determining bedform dimensions, followed by the D50 sand size on the bed. Sand gradation may be unimportant. Key words: seabed, sand, water waves, bedforms, morphology, roughness.
Reliability analysis of wood I-joists
Authors: Foschi R. O. , Yao F. Z.
Published: January 2010

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs. Key words: reliability, limit state design, wood composites, I-joist, structural analysis.
Microcomputer analysis of reinforced concrete slab systems
Authors: Léger Pierre , Paultre Patrick
Published: January 2010

Microcomputer finite element analysis of reinforced concrete slab systems can now be routinely performed to produce realistic numerical simulation of three-dimensional structural behaviour. However, an efficient use of this approach requires an automated integration of design and analysis procedures. Guidelines for proper finite element modelling of slab systems are first presented along with simple post-processing algorithms to perform automatically the design or verifications from the analytical results. Numerical applications on simple slab systems subjected to uniform and concentrated loads are then used to illustrate the relative performance between finite element analyses and the equivalent frame method. Key words: microcomputer, reinforced concrete slab, finite element method, structural design.
Improvement of the return flow allocation in the Water Resources Management Model of Alberta Environment
Authors: Ilich Nesa
Published: January 2010

This paper describes recent developments related to a new return flow algorithm built into the Water Resources Management Model (WRMM) of Alberta Environmental Protection. An earlier return flow allocation method which was used in the WRMM did not always give satisfactory results. It was essential to fix this problem, since correct modelling of the return flows in overall river basin management is of crucial importance. The new return flow algorithm offers more reliable return flow allocation without detrimental effects on the overall model solution. This model is a major river basin planning tool in western Canada used to analyze responses of a river basin to varying operating policies or structural developments. It is a simulation model with a nested optimization subprogram. As a deterministic, steady state, and surface water allocation model, it normally relies on the estimates of natural flows and water demands throughout the river basin. The WRMM can provide quick simulations of any river basin with any number of components within a microcomputer environment. The model is used in ongoing river basin management studies in Alberta and other western provinces in Canada. Key words: water management, computer modelling, simulation, optimization, irrigation.
Strength and stiffness of glulam trusses with punched metal plated joints
Authors: Karacabeyli Erol , Lum Conroy , Olson Link
Published: January 2010

Several Canadian wood truss manufacturers expressed a need to develop technical information to initiate the fabrication and acceptance of wood trusses made with glued-laminated timber (glulam) members and connected by punched metal plates. In collaboration with industrial participants, Forintek Canada Corp. developed a program for testing and analysis of metal plated glulam trusses. Twelve 3/12 pitched chord trusses and three parallel chord trusses, all 13.7 m long, were designed by three different plate manufacturers. All truss fabrication took place at a single truss manufacturing plant. Trusses composed of 79 mm wide and 152-229 mm deep glulam members connected by 16-gauge punched metal plates were tested to failure. The ratio of ultimate to design load averaged 3.5, and varied between 2.7 and 4.4. Both wood and plate failure modes were observed. The results suggest that the sizes of glulam members used in this study are structurally suitable for use with 16-gauge metal connector plates. Key words: wood, trusses, glued-laminated timber, truss plates, strength, stiffness.
Branch plate to reinforced HSS connections in tension and compression
Authors: Dawe J. L. , Guravich S. J.
Published: January 2010

The tension and compression zones of moment plate connections were studied separately by testing branch plate and hollow structural section connections under each type of loading. Square hollow section flanges were reinforced by doubler plates fillet-welded all around. The results from 13 specimens tested in tension indicate that branch plate to reinforcing plate width ratio is an important parameter in joint behaviour. The dominant failure mode was punching shear of the reinforcing plate. The importance of reinforcing plate and HSS wall thicknesses was apparent from the results of 13 specimens tested in the compression series. The capacities of specimens in all but one test in this series were limited by failure of the HSS webs. Key words: hollow structural sections, W-shape, columns, beams, connections, experimental, design, steel.
Bétons à haute performance pour fabriquer des panneaux destinés à réparer des structures submergées
Authors: Sonebi M. , Khayat K. H.
Published: January 2010

The field of repair of submerged hydraulic structures (dams, stilling basins, lock chambers, and so forth) is becoming more and more important given the economic worth of such structures. Damage caused by abrasion can make it difficult to maintain such structures in service. The purpose of the study described in this paper was to develop durable high-performance concretes that can be used for manufacture of board for repair of abrasion-damaged surfaces. The board might also be placed on surfaces already repaired with colloidal concrete poured underwater. Two types of cement (Type 30 and Type 10) and two high-performance coarse aggregates (granite and dolomitic limestone) were used. The eight concrete mixes developed included a variety of additives and admixtures such as silica fume, steel fibre, latex, and superplasticizer. For precise characterization of the mixes, hydraulic abrasion tests, compressive strength tests, and freeze–thaw cycle resistance tests were performed. In addition, shrinkage, thermal expansion coefficient, and permeability of the concretes were measured; in some cases, the board might be subject to freeze–thaw cycles in structures partially emptied for repair or maintenance. Results show that high-performance concretes with very low water: cement ratio, good workability, and improved freeze–thaw cycle resistance can be manufactured. Concretes made with Type-30 cement, silica fume, and granite or limestone aggregate offer excellent hydraulic abrasion resistance (depth of erosion on the order of 1 mm after 72 h), compressive strength greater than 115 MPa after 91 days, and a freeze–thaw durability factor of more than 100%. Key words: abrasion, concrete, durability, steel fibre, silica fume, freeze–thaw cycle, latex, board, underwater repair.
Verification of the material resistance factors in the CSA-S474 code for offshore concrete structures
Authors: Nessim Maher A. , Hong Han Ping , MacGregor James G.
Published: January 2010

The Canadian Standards Association has developed a national code for the design, construction and installation of fixed offshore structures. This code was developed on the basis of probabilistic principles. It consists of five parts (CAN/CSA-S471 to S475), dealing with general loading and design requirements, foundations, steel structures, concrete structures, and sea operations. The material resistance factors cited in the part on concrete structures (S474-M1989) were verified using data typical of offshore structures for a set of representative design cases. The test cases were based on reinforced concrete ice resisting walls with configurations typical of those contemplated for offshore structures in Canada. They covered rare and frequent ice loading for safety classes I and II under flexure, combined flexure and axial force, and shear. The test cases were designed according to the CSA and DnV code provisions, and the reliabilities associated with the resulting members were calculated and assessed. The results indicate that the reliabilities achieved by designing to the CSA standard for safety class I sections are greater than those obtained by designing to DnV rules for all cases considered. Designs carried out according to CSA-S474 meet the target reliabilities implied by CSA-S471 for values of the coefficient of variation of the in situ concrete strength of up to 12% and are, in many cases, very conservative. Sensitivity analysis of safety class I members suggests that the material resistance factors can be increased. Issues that need to be addressed in order to justify an increase in the factors include the acquisition of more data on in situ concrete strength and a more comprehensive consideration of the design conditions covered by the code. The overall consistency of the reliability levels associated with the CSA code can be improved by simultaneous verification of the material factors in CSA-S474 and the load criteria and factors in CSA-S471. Key words: concrete structures, offshore structures, code verification, structural reliability, in situ concrete strength.