bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of 60° equal-leg steel angles according to CSA Standard S37-94
Authors: Madugula Murty K. S. , Adluri Seshu Madhava Rao
Published: January 2010

Sixty-degree equal-leg steel angles find widespread application as leg members of triangular-base lattice towers. Compared to 90° angles of the same size, these angles are weaker in torsional-flexural buckling. The design of such angles is being explicitly covered for the first time in CSA Standard S37-94, "Antennas, towers and antenna-supporting structures." Recent experimental studies have shown that the design of 60° angles will be quite safe, if design is carried out using the expressions for factored axial compressive resistances given in CAN/CSA-S16.1-M89, taking into account only the effect of local buckling and flexural buckling about minor axis, and neglecting torsional-flexural buckling. The Canadian Standards Association Technical Committee on Antenna Towers also noted that the calculated resistances will still be less than the strengths according to the widely used Standard ANSI/ASCE 10-90, "Design of latticed steel transmission structures," which considers all the three modes of buckling. The present paper explains the rationale behind the design procedure adopted by the Technical Committee. Key words: angles, buckling, compression, design strength, schifflerized angles, specifications, steel towers, 60° angles.
Finite element modelling of the shear lag effects in an HSS welded to a gusset plate
Authors: Girard C. , Picard A. , Fafard M.
Published: January 2010

The behavior of a typical connection at the ends of an HSS bracing member was investigated with the finite element method. The connection is effected by means of a gusset plate welded into slots in the HSS member. The paper presents the results of the finite element analyses of 25 connections which differed in the values assigned to the three main parameters that were considered. The finite element results are compared with the provisions of CSA Standard S16.1-M89, and some adjustments to these provisions are recommended. Key words: connections, steel, shear lag, finite element, hollow section, gusset.
Modelling floodplain conveyance in compound channel flows
Authors: Chatila Jean G. , Townsend Ron D.
Published: January 2010

Floodplain conveyance in compound channel flows is examined through applications of the dynamic flow routing model DWOPER to both laboratory and field data sets. Three different approaches regarding the modelling of off-channel storage are considered, namely, the single-channel approach and two interface-plane methods, which artificially separate main channel flows from floodplain flows, using (i) vertical and (ii) diagonal interface planes. The single-channel method, which views composite flow fields as single units without storage, produced significant differences between simulated and observed stage and discharge hydrographs. The vertical interface method gave generally good results in the case of the laboratory data, but was less successful when applied to the field data. The diagonal interface method, which in this instance applied outward-facing diagonal interface planes at the junctions of the main channel and floodplain zones, produced superior results overall. Key words: floodplain, conveyance, unsteady flow, compound channels, off-channel storage, interface planes.
Micro-fiber reinforced cement composites. II. Flexural response and fracture studies
Authors: Banthia N. , Sheng J.
Published: January 2010

In Part I of this paper, stress–strain curves for micro-fiber reinforced cement-based composites containing high volume fractions of carbon, steel, and polypropylene fibers were obtained. Considerable strengthening, toughening, and stiffening of the host matrix due to micro-fiber reinforcement under both static and impact conditions were reported. In this paper, composites are characterized under an applied flexural load. Both notched and unnotched specimens were tested in four-point flexure; significant improvements in the flexural behavior due to fiber reinforcement were noted. Notched specimens were tested to study the growth of cracks in these composites and to develop a valid fracture criterion. With this objective, crack growth resistance curves and crack opening resistance curves in terms of the stress intensity factor were constructed. The paper recognizes the potential of these composites in various applications and stresses the need for further research. Key words: Portland cement-based materials, fiber reinforcement, fracture toughness, R-curves.
Shear connections using stub tees between W beams and HSS columns
Authors: Dawe J. L. , Mehendale S. V.
Published: January 2010

Ten full-scale specimens consisting of wide-flange beams shear connected by means of tee stubs to hollow structural section (HSS) column faces were tested. Shear–displacement and shear–rotation behaviour were documented and five possible failure modes were identified for this type of connection. In all cases, excessive displacements resulted from yielding of the tee stem, while different ultimate failure modes were observed. Except for bending of the HSS wall, the identified failure modes could be related to well-known limit states. Quantitative evaluations were provided for the remaining failure modes. Key words: connection, steel, HSS, W shape, shear, column, beam, tee stub, experimental.
Effects of tire – pavement contact pressure distributions on the response of asphalt concrete pavements
Authors: Yue Zhong Qi , Svec Otto J.
Published: January 2010

The paper presents the development of a computer program VIEM for the elastic analysis of multilayered elastic pavements under the action of arbitrary tire–pavement contact pressure distributions. The techniques adapted in VIEM primarily involves the use of a two-dimensional numerical integration to integrate point load solutions over the distributed pressure after discretizing the contact area into a finite number of triangular or quadrilateral elements. Values of contact pressure are inputted at the node points of discretized area. Numerical verification of VIEM indicates that numerical solution of high accuracy can be efficiently calculated for the elastic response of multilayered asphalt pavements. As a result, the determination of displacements and stresses (strains) can be achieved using a personal computer. With the use of VIEM, a theoretical investigation is further performed to illustrate the effects of tire–pavement contact pressure distributions on the response of asphalt concrete pavements. An in situ measured tire–pavement contact pressure distribution is utilized in the investigation. The response of asphalt concrete pavements due to the action of this measured contact pressure distribution is examined and compared with that due to the action of a uniform and circular contact pressure distribution by taking into account the influences of moduli and thicknesses of structural layers. The results of this investigation confirm theoretically a general consensus that details of the contact pressure distribution affect stresses and strains near the surface of the pavement, whereas the response in the lower layers depends mainly on the overall load. In particular, the contact pressure distributions have a significant effect on the horizontal tensile strains at the bottom of thin asphalt concrete layer which control the fatigue failure of asphalt pavements. Key words: tire–pavevment interaction, three-dimensional stress analysis, asphalt concrete pavements, numerical integration, multilayered elastic solids, point load solution.
Behaviour of concrete block masonry prisms under axial compression
Authors: Fahmy E. H. , Ghoneim T. G. M.
Published: January 2010

A nonlinear three-dimensional finite element model was developed to study the complex behavior of ungrouted and grouted concrete block masonry prisms under axial compression. The model detects crack initiation and traces crack propagation in the masonry assemblage. Variable strengths for blocks, mortar, and grout were used to study the effect of the mechanical properties of prism constituents, and their combinations, on the prism strength and modulus of elasticity. The effect of the number of courses was also investigated. The results of the finite element analysis were used to develop simplified relationships to predict prism strength and modulus of elasticity. Good agreement was observed between the available experimental data and the predicted prism strengths. Key words: compressive strength, concrete blocks, failure modes, finite element, masonry, modulus of elasticity, prisms.
Effets de l'ozonation et de la filtration biologique sur la demande en chlore et sur les précurseurs de trihalométhanes et des composés organo-halogénés totaux
Authors: Baribeau Hélène , Prévost Michèle , Desjardins Raymond , Lafrance Pierre , Legube Bernard
Published: January 2010

The effects of biological treatment (ozonation followed by biological activated carbon filtration (BAC)) on chlorine demand and on formation of trihalomethanes (THM) and total organic halides compounds (TOH) were studied at the Sainte-Rose water treatment facility, Laval. The plant influent is a surface water with a dissolved organic carbon of 6–7 mg/L. Results showed that ozonation marginally reduced (0–6%) short term chlorine demand but that BAC filtration reduced it by 40–55%. Ozonation versus BAC filtration was found to effect THM and TOH formation differently from the removal of the chlorine demand. THM (4-h contact with chlorine) and TOH formations were reduced by 48–60% and 39%, respectively, via ozonation. With BAC filtration, THM and TOH formations were reduced by 20–34% and 16%, respectively, with respect to the ozonated influent. For all essays, an initial significant decrease in residual chlorine was followed by an increase in TOH and subsequently in THM. The initial chlorine doses used for measuring the chlorine demand were found to have an effect on the final results. An increase in the initial chlorine dose resulted in a higher chlorine demand as well as in higher THM and TOH formations. The effect was found to be more profound at chlorine doses less than 3 mg Cl2/mg total organic carbon. Key words: chlorine demand, chlorination by-products, trihalomethane, total organic halides, ozonation, filtration, biological activated carbon.
Stochastic analysis of structures with passive seismic control
Authors: Pandey Mahesh D.
Published: January 2010

In modern building design, the installation of passive control devices such as friction cross-bracings and viscoelastic dampers is considered an attractive option for controlling structural damage due to an earthquake. These control devices, like safety valves, allow earthquake energy dissipation at purposely designed locations such that ductility demands on other structural members are greatly reduced. The paper presents a nonlinear stochastic analysis procedure for large building structures equipped with passive control devices using the method of equivalent linearization. A generalization of this method, based on the Monte Carlo simulation technique, is elaborated for linearizing a multidimensional hysteretic restoring force law in a manner compatible with existing finite element programs. To illustrate the procedure, response statistics of a nonlinear oscillator, a friction damped structure, and a 10-storey building subjected to random excitation are analyzed. The study highlights that friction connections are useful in controlling seismic response of building structures. Key words: stochastic dynamics, Markov process, equivalent linearization, earthquake, passive control, Monte Carlo simulation, hysteresis, filtered white noise, covariance, friction cross-bracing.
Hydraulic loading in culvert inlets
Authors: Moawad A. , McCorquodale J. A. , Abdel-Sayed G.
Published: January 2010

Flexible corrugated metal pipes are commonly used as an alternative to concrete bridges for small and medium sized streams. If these flexible culverts are improperly designed they can fail dramatically. One cause of failure is uplift at a submerged inlet. With the pipe flowing partly full, the weight of the pipe and the net force due to the internal water pressure may be less than the buoyant force acting on the submerged pipe; this may result in an upward bending moment. This paper describes an experimental study of the hydraulic forces inside culvert inlets. The tests were carried out on a plexiglass pipe with projecting and flush inlets. The effect of the flow separation on the pressure fluctuation at the inlet was investigated in this study. The internal pressures for the case with a headwall were found to be significantly higher than for the projecting inlet. The formation of a scour hole at the upstream end of the inlet increased the uplift potential. Internal pressure profiles were integrated to determine the internal load distributions on culverts with different inlet treatments. Key words: culvert, projecting inlets, headwall inlets, uplift failure, scour, hydraulic loading.
Effects of end distance and thickness on the tensile resistance of 102 mm shear plates
Authors: Quenneville P. , Charron A.
Published: January 2010

In this paper, an experimental study of the behavior of 102 mm shear plates subjected to tensile load is presented. The design requirements for shear plate connectors specified in the last three editions of the Canadian wood design standards (1980, 1984, and 1989) are also reviewed and compared with the experimental results. In the experimental study, 83 specimens were tested with shear plate end distances of 80, 145, 210, and 275 mm. Specimens were either 64 or 89 mm thick. Results for all tests were analyzed and 5th percentile resistance values were obtained for each end distance value, assuming a two-parameter Weibull distribution. Results show that connections using 102 mm shear plate connectors behave in a brittle manner when loaded in tension. It is also shown that the member thickness affects the tensile resistance of shear plates in thin members with small connector end distances and that it appears to impose a limit on the resistance for thin members with large connector end distances. Finally, it is shown that the 75% minimum limit on a member net area adjacent to a connector unit (clause 4.3.7.2 of O86.1-M89) is conservative for members with small connector end distances. Key words: wood, shear plate, end distance, resistance, thickness.
Three-dimensional analysis of soil – steel bridges
Authors: Girges Youssef , Abdel-Sayed George
Published: January 2010

The present design of soil–steel bridges is based on plane-strain analysis by considering a slice of a unit width of the conduit wall and the surrounding soil. This two-dimensional analysis neglects the third-dimensional effect of the steel shell and the soil continuum which could be significant especially when the load varies in the longitudinal direction, as in the case of live load acting over a shallow cover. The structure is also subjected to a varying dead load due to the variation in the depth of cover from maximum at the middle part of the conduit to zero at the conduit edges. A three-dimensional finite element analysis is presented in this paper to examine the actual three-dimensional behaviour of soil-steel bridges. The thrust and bending moment around the conduit walls as well as the stability of a single conduit are presented and compared with the results obtained from plane-strain analysis. Also, the live load dispersion in the soil above the conduit is examined and compared with some present codes. The study leads to evaluation of the degree of approximation inherited with the practical approaches of the two-dimensional analysis. Key words: conduit, corrugated steel, three-dimensional analysis, stability, soil–steel bridges.
Influence of the assumed effective length factor on the load carrying capacity of steel angles in compression
Authors: Temple Murray C. , Petretta Davide M. , Morand Catherine
Published: January 2010

Single angle compression members are usually attached by one leg only. In Canada it is common practice when designing such members to neglect the end eccentricities, to assume the angle buckles about the minor principal axis, and to assume an effective length factor of 1.0. Clause 13.3.1 of S16.1 is then used to calculate the compressive resistance. An experimental program was undertaken to determine the effect that the assumed effective length factor has on the compressive resistance of such angles. Eighteen specimens were tested in which the angles were slender or of intermediate length. The effective length factor was assumed to be 1.0, 0.9, or 0.5. It was determined that when there is substantial restraint at the ends of the angles the assumed effective length factor has a very significant effect on the compressive resistance of an angle attached by one leg. Key words: angles, axis of bending, buckling, design procedure, effective length factor.
Data flow model for communications between project participants in a highway bridge project
Authors: Abou-Zeid Azza , Russell Jeffrey S. , Hanna Awad S. , Park Sang C.
Published: January 2010

The construction industry is highly fragmented. A large number of diverse organizations participate in the planning, design, and construction of each constructed project. Cooperation between project participants necessitates the transfer of large quantities of project information. Communication, in many forms, is the means for data exchange among participants. Availability and timeliness of the data needed to perform different project tasks may decrease the potential for project delay(s) and rework, thus increase productivity. This paper discusses the use of the "structured analysis" methodology to document the communication process. The paper also discusses the use of a shared-data resource to solve some of the communication and standardization problems in the construction industry. An overview of the structured analysis methodology is provided. Data flow diagrams, a data dictionary, and transform descriptions comprise the tools for implementing structured analysis. Each tool is briefly described with emphasis given to data flow diagrams. Portions of the communication process documented for a highway bridge project administered by Wisconsin Department of Transportation are provided as an example to illustrate the use of data flow diagrams for information flow identification. The example also presents the use of the data dictionary as a supplementary document to provide composition and definition of data elements. Selected communication difficulties among project participants as well as potential areas of modifications and (or) automation in the current system are highlighted. This paper provides a framework for tracking and documenting the information flow between project participants. Key words: data flow model, data flow diagram, bridge construction, structured analysis, communication.
Evaluating truck weight regulatory policies
Authors: Fekpe Edward
Published: January 2010

An improved methodology for evaluating infrastructure impacts and trucking productivity of different truck types operating under alternative truck weight limits and enforcement strategies is presented. The procedure accounts for the effects of enforcement on weight distributions in an objective manner allowing the consequences of adopting alternative weight control schedules to be determined. The methodology resolves some major uncertainties surrounding pertinent input variables required in evaluating truck weight regulatory policies. Key words: weight limit, enforcement, evaluation, pavement loading, payloads.
Northumberland Strait bridge: analysis techniques and results
Authors: Ghali Amin , Tadras Gamil , Langohr Paul H.
Published: January 2010

The Northumberland Strait at the Atlantic coast of Canada will be crossed by a 13 km bridge. The major part of the superstructure will consist of 44 spans, each of length 250 m and a box cross section of variable depth 4.5–14 m. The superstructure, divided into units of maximum length 192 m, will be produced in a yard by segmental casting and multistage prestressing. These units will be assembled at their final position on top of the piers. Each pier is composed of two pieces, also produced in the yard and connected on site by cast in situ concrete. This paper describes selected analysis problems and their solutions employed in the structural design. The analysis problems are concerned with (i) dynamic response to ice forces; (ii) movements of pier footings and stiffness of the subgrade; (iii) variation of stresses and deformations during construction and during the life of the structure, considering the effects of creep and shrinkage of concrete and relaxation of the prestressed steel; and (iv) thermal stresses. Key words: bridges, concrete, creep, prestress relaxation, segmental construction, shrinkage, strait crossing.
Utilization of the relative rigidity concept to predict the failure of pipe systems under explosive loads
Authors: Halim A. O. Abd El , Lau D. T. , Razaqpur A. G. , Winterink J. A.
Published: January 2010

The interaction between loading plates and supporting structures is very much dependent upon the relative rigidity of the system. This paper first illustrates how an indiscriminate application of the relative rigidity concept can lead to erroneous conclusions in such systems. The paper then applies the concept to explain reported observed failure modes in pipe systems under explosive loads. Numerical studies are presented which simulate the behaviour of square pipe systems under static and explosive loads using the concept of relative rigidity in conjunction with the finite element method. The results of the analysis confirm the hypothesis of the relative rigidity concept. Experimental verification of the theoretical predictions and numerical modelling results are obtained by simulating the explosive failure patterns in simple freezing experiments. The analysis presented in this paper demonstrates the importance of the concept of relative rigidity for explaining certain kinds of observed failure and fracture phenomena. Key words: cracks, explosives, geometric distortion, load transmitting plate, pipes, relative rigidity, soil – foundation interaction, stress waves.
Contractor selection: qualification and bid evaluation
Authors: Rankin Jeff H. , Champion Stephen L. , Waugh Lloyd M.
Published: January 2010

Historically the selection of contractors in North America was almost exclusively based on the lowest tendered price. Owners utilized competitive tendering for its simplicity and fairness in the award process. More recently, owners have reconsidered the use of low price as the basis for selecting contractors and therefore have attempted to modify the traditional low bid system with qualification and evaluation clauses. Qualification and evaluation clauses have caused considerable controversy in the public sector, where contractors are concerned about the legitimacy of tendering procedures when public funds are used. Although contractors agree that the system needs improvement, there are conflicting views on what should be done. This paper provides a summary of traditional tendering procedures and illustrates two possible modifications to the contractor selection process. The intended audience is practicing professionals, particularly those in the public sector where the objectivity of the tendering process is under such scrutiny. Evaluation is selected as the direction with the most potential for improvements. The evaluation option is analyzed by examining its legal implications through a discussion of recent case law. Finally, recommendations for implementing an evaluation system are discussed to address the issues identified through the legal discussion and from the opposing views in the construction industry. Key words: construction, contract law, competitive bidding, contractor qualification, bid evaluation.
A new method and apparatus for evaluation of the K-slump of concrete
Authors: Nasser K. W. , Biswas S.
Published: January 2010

This paper introduces a new digital model of the K-slump tester. For the new tester (patent pending), it is theoretically shown that an inverse linear relationship exists between the K-slump of freshly mixed concrete or mortar and the yield stress τ0 in the Bingham model. The validity of this relation was investigated experimentally. Tests were conducted on cement pastes, mortar, and fresh concrete mixtures using a Hobart food mixer and the new tester. Power consumed by the mixer at three different speeds was measured along with the K-slumps for fresh concrete mixtures. The results give excellent agreement with the theoretically derived relationship. Hence, the K-slump of concrete was shown to be related to the yield stress τ0 by the equation K = Kmax − (constant × τ0), where Kmax is the maximum K-slump. To determine the precision of the new tester, an interoperator reliability test program was carried out in accordance with ASTM designation C 802. The results indicate that the new apparatus is accurate and reliable in evaluating the K-slump of fresh concrete. Key words: cement paste, concrete, consistency, flow, flowability, fresh concrete, K-slump, mortar, slump, rheology, workability.
A time – cost trade-off algorithm for nonserial linear projects
Authors: Senouci Ahmed B. , Eldin Neil N.
Published: January 2010

In the last decade, a number of methods based on the theories of linear and dynamic programming were developed for the scheduling of linear projects. However, these methods are only capable of handling sequential or serial activities. In this paper, a dynamic programming formulation for the scheduling of nonsequential or nonserial activities is presented. The objective of the current formulation is to determine the project time–cost profile, which determines possible project durations and their minimum project total costs. The formulation considers the effects of crew formations, interruptions, and lags for production activities in determining the minimum project total cost, minimum project direct cost, and minimum project duration. In addition, the approach presented is capable of handling activity durations and interruptions described by continuous and discrete functions. The formulation is also capable of handling both serial and nonserial linear projects. An example project is provided to illustrate the computational steps, validate the calculation algorithm, and show the capabilities of the proposed method. Key words: time-cost trade-off, linear projects, planning and scheduling, project control, project management, nonserial linear projects.
Interpretation of in situ borehole ice strength measurement tests
Authors: Masterson D. M.
Published: January 2010

A hydraulic borehole jack for the testing of ice confined compressive strength and elastic modulus through the depth of a 150 mm hole at regular intervals is described. Interpretation of the pressure and deformation information obtained is accomplished using standard equilibrium and compatibility equations for plate bearing tests applied to the expansion of a cavity of crushed material surrounded by an elastic medium. The jack tests yield confined compressive strength and elastic modulus. These are basic, universally understood, engineering properties of a material useful in practice. The jack has been used successfully to determine the in situ strength and stiffness at any combination of depths required in a wide variety of conglomerate freshwater and sea ice. The results have been used to verify the strength and bearing capacity of ice platforms and roads and to help quantify global ice loads and local ice pressures on offshore structures. Key words: ice, ice testing, borehole testing, ice strength, ice roads, ice structures, field testing, field strength testing, in situ strength, in situ testing, ice in situ testing, ice platforms.
Two case studies of dilution models applied to thermal discharges
Authors: Valeo C. , Tsanis I. K.
Published: January 2010

The United States Environmental Protection Agency models CORMIX2 and UM were used to predict the ambient temperature rises from thermal discharges near Charlestown, Rhode Island, and Jamesport, Long Island, New York. Observations from two scaled model laboratory studies conducted at Alden Research Laboratories Inc. (ARL) were compared with temperature rise predictions from two numerical models. For the ARL diffuser at Jamesport, both numerical models underestimated the observed temperature rises. In the Charlestown study, UM produced results that were in good agreement with the temperature rises observed, whereas CORMIX2 underpredicted observations but remained within the model's stipulated ±50% error. However, UM was unable to model the plume shape properly, since it is primarily intended for alternating diffusers. The predicted wastefield shapes of CORMIX2 were similar to those observed in the laboratory but of greater surface area. Key words: multiport diffusers, thermal discharges, initial dilution.
Validation des données hydrométriques par des techniques multivariées de filtrage
Authors: Bennis Saad , Côté Sylvain , Kang Narut
Published: January 2010

The purpose of this research project was to develop a method for automatic validation of historical daily natural runoff data. Reservoir level measurements, on which natural runoff calculations are directly based were validated. Depending on the number of limnimeters installed, two different approaches were used to validate and adjust reservoir level times series. The best conditions (those discussed here) are when a reservoir has several water-level stations. Under these conditions, multivariate filtering is used to validate time series of recorded levels at each station. This method, called the multifilter method consists of comparing deviations between the value predicted with an autoregressive model, the measured historical value, and an estimate obtained using a regression model at neighbouring stations. Among the measured value and the estimate derived from the linear regression model, the closest value to the forecast was retained. One advantage in validating historical hydrometric data is the availability of data before and after the date to be validated. In other words, to validate the value of level Nt not only are the values Nt−1Nt−2, … available, but also the values Nt+1, Nt+2 … at the station to be validated as well as at neighbouring stations. To take advantage of this, the multifilter validation process was performed twice: in the usual time direction and backwards. The historical value was considered faulty and discarded only if it was rejected in both the forward and backward validation processes. All techniques developed have been incorporated into the software called ValiDeb and successfully tested at the Gatineau River site in Quebec. Key words: validation, filtering, multivariate, equipment redundance, analysis, levels, runoff, Kalman. [Journal translation]
Improving earthmoving estimating by more realistic knowledge
Authors: Christian John , Xie Tian Xing
Published: January 2010

Earthmoving operations are often a very important aspect of a civil engineering project. Very accurate knowledge of the earthmoving operation is often the vital, critical element in the formation of a good and accurate cost estimate and schedule because of its prominent role in influencing costs and time. Inaccuracies are often built into earthmoving estimates by the fairly sweeping assumptions that are made during the estimating process. These problems were revealed in answers to a questionnaire and in interviews with experts. The factors that affect the performance of machines are discussed, including the common types of earthmoving operations. The importance of haul distance in determining which type of equipment should be used is also considered. The selection of equipment and estimation of costs for earthmoving depend heavily on human experience. The means of eliciting human experience are described in detail. Because of this reliance on human experience, a prototype knowledge-based expert system was developed using a shell program. The system is able to select the most appropriate fleet of machines, and estimate the cost, for use as a decision support system in planning an earthmoving operation. Key words: construction, earthmoving, estimating, knowledge, expert system, realistic knowledge.
A simple equation for axially loaded steel column design curves
Authors: Loov Robert
Published: January 2010

Clause 13.3 of the Canadian Standards Association Standard CAN/CSA-S16.1-M89 "Limit states design of steel structures" utilizes complex five-piece curves to specify the limiting capacity of axially loaded steel columns. A study of these equations shows that they do not fit smoothly together. The resulting curves are scalloped. It has been found that the five-piece curves can be replaced by one continuous equation which never deviates by more than approximately 3% from the S16.1-M89 values. The proposed equation is applicable to all three column curves of the Structural Stability Research Council with only a change in the value of the exponent. The proposed equation has been adopted in the recently published CAN/CSA-S16.1-94 standard. Key words: axial loads, columns, inelastic analysis, steel columns.
New provisions for shear lag in steel tension members
Authors: Albert Charles
Published: January 2010

The Canadian Standards Association Standard CAN/CSA-S16.1-94 provides new design rules for calculating the effective net area of steel tension members connected by a single line of weld, or by a combination of transverse and longitudinal welds. The significance of the new provisions on the design of angles is examined by means of a parametric study. Key words: shear lag, tension members, welded connections.
Conditionnement et déshydratation de boues d'étangs aérés facultatifs à l'aide du gel – dégel naturel: résultats d'essais
Authors: Desjardins Marc-André , Brière François G.
Published: January 2010

This article presents the results of tests investigating the conditioning and dewatering of biological and chemical sludge (alum dephosphatation sludge) from facultative aerated lagoons using natural freeze–thaw. The results presented here highlight the excellent efficiency of this conditioning method used with drying beds. Following freeze–thaw, immediately after drainage, sludge presents little odor and has lost its liquid state since dry solid contents of more than 30% can be obtained with ease. Freeze–thaw also eliminates the gelatinous consistency of chemical sludge. The filtrates are clear and contain low levels of suspended solids but may have relatively high chemical oxygen demand. To maximize the depth of sludge that can be frozen, it is necessary to freeze the sludge in thin layers. This requires the pumping of sludge from a separate storage basin to a freezing bed for the duration of winter (separate basin–bed method). The storage basin may however be combined with the freezing bed provided the depth of the sole sludge layer does not exceed the maximum depth of sludge that can be frozen during the winter season (combined basin–bed method). Freeze–thaw is not affected by the initial dry solid content of the sludge. The grain size of the sludge can however have some influence, although quite marginal, and freeze–thaw is efficient for all types of aqueous sludge. Key words: conditioning, dewatering, sludge, facultative aerated lagoons, natural freeze–thaw, trials.
Optimization of the Regional Municipality of Ottawa-Carleton's water supply system operations. I. Model development
Authors: Pelletier Geneviève , Townsend Ronald D.
Published: January 2010

The principal objective of this study was to optimize pump scheduling and reservoir releases in the Regional Municipality of Ottawa-Carleton's (RMOC) water supply system with a view to reducing electricity-related operating costs. Pump schedules and reservoir releases for enhanced operation were obtained using a linear programming optimization model that incorporated Ottawa Hydro's electricity tariff structure for "large" users. A second objective was to investigate the impact on system operating costs of increasing (i) reservoir storage capacity, (ii) treatment plant capacity, and (iii) water demand by consumers. This paper (part I) describes the RMOC distribution system and reviews the model development. The next paper (part II) presents the analyses performed for the two study objectives, and important results. Key words: water supply system, pump scheduling, pumping costs, optimization, modelling.
Design for punching shear in concrete: critical review of Canadian Standard CSA-A23.3-94
Authors: Ghali Amin , Megally Sami
Published: January 2010

The requirements of the new Canadian Standard CSA-A23.3-94 "Design of concrete structures" to avoid punching failure of slabs at their connections with columns are critically reviewed. Changes are proposed to avoid unsafe design and to cover practical situations not adequately treated by the Standard. Key words: columns, connections, flat concrete plates, punching shear, reinforced concrete, shear reinforcement, shear strength, stud shear reinforcement, slabs.
Punching shear provisions for reinforced and presfressed concrete flat slabs
Authors: Gardner N. J.
Published: January 2010

The validity of the CSA A23.3-94 code provisions for punching shear were compared with the punching shear results of 142 reinforced concrete flat slabs, 16 prestressed concrete flat slabs with unbonded tendons, and 17 flat slabs with unbonded prestressed and supplementary bonded reinforcement. The code prediction equations are not capable of direct verification against experimental results without using a correction factor. Using a justifiable correction factor, the CSA A23.3-94 provisions are appropriately conservative for reinforced concrete slabs but the scatter is large. However, it was concluded that the CSA A23.3-94 provisions are not conservative for prestressed concrete flat slabs. An equation is proposed to calculate the punching shear capacity of reinforced concrete and prestressed concrete slabs, which has a smaller coefficient of variation than the punching shear provisions of CSA A23.3-94, for symmetrically loaded interior columns. The critical section of the proposed method is the perimeter of the column, which is easier to justify than an arbitrary critical perimeter half the effective depth of slab from the column. Key words: reinforced concrete, prestressed concrete, flab slabs, punching shear.
Hydraulic flood routing with minimal channel data: Peace River, Canada
Authors: Hicks Faye E.
Published: January 2010

Hydrologic flood routing models have been, and continue to be, the primary tool of the flood forecaster. However, any advancement in our ability to model a wider variety of flow scenarios, including extreme flood events (for which no calibration may be available), dam break floods, or ice-related events, necessitates the use of deterministic (hydraulic) models. A more fundamental advantage of hydraulic flood routing models over hydrologic models, in terms of less dynamic events, is that output describing flood hydrographs between gauge sites is produced. Such output is valuable in flow forecasting, and as input to the hydraulic analyses required for floodplain delineation. To date, hydraulic flood routing models have not gained widespread use for two key reasons. First, they present a particularly challenging numerical problem. Second, they are seen to be data intensive, requiring geometric data over the entire modelled reach. The former problem is no longer the primary concern, as recent research has led to the development of numerous robust computational schemes. The intensive data requirements of hydraulic models are much more limiting from a practical perspective, as flood routing typically involves very long reaches and the cost of obtaining sufficient cross section data is generally prohibitive. In this investigation, the reliability of a hydraulic flood routing model based on limited cross section survey data is evaluated for the case of the Peace River in British Columbia and Alberta. Based on the successful results of these investigations, it is concluded that a reliable hydraulic flood routing model can be developed with limited field data supplemented with topographic map data. Key words: flood routing, St. Venant equations, Peace River, characteristic-dissipative Galerkin scheme, finite element method.
Neural network-based modelling of the adequate chlorine dosage for drinking water disinfection
Authors: Rodriguez Manuel J. , Sérodes Jean-B.
Published: January 2010

A neural network modelling approach has been developed to estimate the disinfectant dose adjustments required during water re-chlorination in storage tanks. The approach is based on representative operational and water quality historical data which intrinsically characterize the operators' use of know-how in their routine tasks. The development of the model requires the elimination of the historical cases in which re-chlorination results were inadequate. The results obtained for the model demonstrate that neural networks are capable of satisfactorily identifying the knowledge patterns contained in data with regard to the re-chlorination process for both winter and summer conditions. The practical use of such a model may assist operators in adjusting re-chlorination doses and may favour chlorine economization and the improvement of the water quality in the distribution system. Key words: drinking water, neural networks, distribution systems, chlorination, modelling, water quality.
Performance of timber structures during the Hyogo-ken Nanbu earthquake of 17 January 1995
Authors: Prion Helmut G. L. , Filiatrault André
Published: January 2010

The Hyogo-ken Nanbu earthquake that struck the Kobe area of Japan on January 17, 1995, caused extensive damage to wooden housing structures, resulting in a large loss of life. As part of the Canadian Association for Earthquake Engineering reconnaissance team, the authors visited the disaster area a week after the earthquake to gain insight into the performance of timber structures. This paper reports their findings and discusses the reasons for the poor behaviour of the many buildings that were destroyed as well as the reasons why some buildings survived almost unscathed. A summary of Japanese code practices provides background to the discussions and allows comparisons with Canadian design and construction methods. Key words: earthquakes, seismic, timber, wood framed buildings, housing.
Performance of concrete bridges during the Hyogo-ken Nanbu (Kobe) earthquake on January 17, 1995
Authors: Anderson Donald L. , Mitchell Denis , Tinawi René G.
Published: January 2010

Examples of failures of concrete bridges during the Kobe earthquake are presented. Types of failures and their probable causes are discussed, and photographs of reinforcement detailing in the failed columns are shown. An example of the reinforcement in a new bridge column under construction at the time of the earthquake, showing modern detailing standards, is given. Key words: Kobe, Hyogo-ken Nanbu, earthquake, seismic, concrete, bridges, damage.
Some geotechnical aspects of the Hyogo-ken Nanbu (Kobe) earthquake of January 17, 1995
Authors: Finn W. D. Liam , Byrne P. M. , Evans S. , Law T.
Published: January 2010

A geological and seismological framework is provided for understanding the damage to structures resulting from soil conditions. The paper focusses on the large-scale failures of the quay walls in Kobe Port due to liquefaction, and contrasts the performance of structures in improved and unimproved ground. Soil–structure interaction problems such as pile foundations, bridge piers, lifelines, and an underground subway station are also described. These failures have important implications for seismic design in the Fraser Delta in British Columbia, which has the potential for extensive liquefaction during a major earthquake. Key words: ground motions, directivity effects, liquefaction, lateral spreading, seismic settlements, seismic damage, port facilities, ground improvement.
Shear design off high strength concrete beams — Canadian code perspective
Authors: Polak Maria Anna , Dubas Jaroslaw J.
Published: January 2010

The paper presents the results of an investigation of the influence of concrete compressive strength on the shear strength of reinforced concrete beams, both nonprestressed and prestressed. A total of 132 existing tests on high strength concrete beams, with and without shear reinforcement, were analyzed and compared with the shear design provisions of the CSA Standard CAN3-A23.3-M94 and the previous version of the code, CAN3-A23.3-M84. The main parameter in the investigation was the concrete compressive strength. Owing to the complex nature of shear behaviour and the interdependence of the factors affecting shear strength, other parameters such as the shear span to depth ratio, the longitudinal reinforcement ratio, and the amount of shear reinforcement were varied, as well as the concrete strength. Key words: shear, beams, high strength concrete, code methods, shear reinforcement index, shear ratio, predictions, strength.
Economical design for long-span soil – metal structures
Authors: Mohammed Hesham , Kennedy John B.
Published: January 2010

Soil – metal structures consisting of metal conduits covered with soil have been used extensively for short-span bridges. Recently, some designers ventured into utilizing them for longer spans with shallow soil cover which has led to some failures. Long-span soil – metal structures are often designed with transverse stiffeners attached to the metal structure. Another approach is the use of a reinforced-soil system in which the surrounding soil is reinforced and the metal conduit is tied into the soil. In this paper, a three-dimensional analysis of long-span soil – metal structures is carried out using these two approaches. The analysis is verified and substantiated by results from laboratory models. The structural responses from the two designs show that the latter design approach leads to a more economical structure. A design example based on the Cheese Factory Bridge built in Ontario in 1984 is presented. Key words: bridges, design, long span, reinforced soil, soil – metal structures, structural engineering, three-dimensional analysis.
Validation des données hydrométriques par des techniques univariées de filtrage
Authors: Berrada Faouzi , Bennis Saad , Gagnon Luc
Published: January 2010

This study aims at validating the historical hydrological data. For the purpose of clarity, the paper has been divided into two parts. The first part, a theoretical one, presents a very broad range of filtering techniques that goes from the simple filter, using the median or the moving average, to the Fraser smoother coupled with the Kalman one. A chronological series simulated and then artificially affected by noise effects, simultaneously with white noise and a certain number of high-amplitude perturbations, was conceived. Its use should allow to reach conclusions regarding the validity and performance of the different filters. The second part, a practical one, uses several actual historical series relative to measures of the water level in a reservoir, the natural inflow, and inlet and outlet flows. Its essential objective is to validate the natural inflow data (calculated by hydric balance). A general chart of the procedure employed to carry out this validation is thus presented. The results obtained are then compared. All the techniques are used so as to make the validation automatic. This resulted in creating a very general application software called Valideb. It allows the user to analyze and judge the results of a filtering method and its effect on each component of the hydric balance. Key words: validation, filtering, smoothing, natural inflow, water level, flow, covariance, noise, Kalman, Fraser. [Journal translation]