bluuebunny/crossref_metadata_2025 huggingface dataset:
Prévision des températures de l'eau en rivières à l'aide d'un modèle conceptuel : le cas de la rivière Moisie
Authors: Morin Guy , Nzakimuena Tonino-Joseph , Sochanski Wanda
Published: January 2010

Hydro-Québec is projecting to increase the hydroelectric production capacity of the St. Marguerite River by diversion of the tributaries Pékans and Carheil rivers of the Moisie River, the most productive salmon river of the whole Quebec. Along with substantial changes in hydrological regimes, this hydroelectric development is most likely to affect some physical environment factors such as the water temperature, which is of prime importance for the biotope and, in particular, for the salmon productivity. The objective of the present study is to simulate, over a long period of time, the river water temperatures under natural conditions as compare to those after the impoundment, to assess the consequences of the tributary diversion. We used the hydrological CEQUEAU model coupled with a temperature model.The temperature model developed is applicable to the ice-free period and calculates daily water temperatures in rivers by computing an energy budget to each element of the watershed. The energy budget considers the short-wave solar radiation, long-wave radiation, evaporation, and convection in the air as well as the advective heat of various inflows from surface runoff, interflow, and groundwaters. The estimation of the atmospheric thermal exchanges is based on the equations usually found in literature. The volumes of the various inflows are given by the hydrological model. The temperature model uses daily data for air temperature and monthly data for solar radiation, cloudiness, wind speed, and vapour pressure.The model has been applied to the Moisie River (Québec), using the measured values for the calibration. Both observed and calculated values show good agreement. The model was also used to simulate, over the whole watershed, the water temperatures for the 1961–1989 period and after the diversion. The results show that the tributary diversion contributed to increase the water temperature of the Moisie River and that this increase is gradually attenuated as we progress downstream. Key words: temperature, impacts, model, Moisie, Québec, diversion, hydrology.
Bond between epoxy-coated reinforcing bars and concrete under impact loading
Authors: Yan Cheng , Mindess Sidney
Published: January 2010

The bond between epoxy-coated reinforcing bars and concrete under static, high strain rate, and impact loading was studied for plain concrete, polypropylene fibre reinforced concrete, and steel fibre reinforced concrete. The bond stress, slip, crack development, the bond stress–slip relationship, and the fracture energy during the bond-slip process were investigated experimentally. The results were compared with those for uncoated reinforcing bars. It was found that for epoxy-coated rebars, the bond resistance decreased, in terms of the maximum local bond stress and the average bond stress; wider cracks developed during the bond process; and the fracture energy during bond failure decreased. It was also found that the influence of epoxy coating on the bond behaviour for push-in loading was much more significant than for pull-out loading. However, steel fibre additions at a sufficient content, and higher concrete strength, can mitigate the above effects to a considerable degree. Polypropylene fibres were much less effective in this regard than steel fibres. Key words: epoxy-coated rebars, bond, fibre concrete, strain rate, impact steel fibres, polypropylene fibres, concrete, high strength concrete.
The flexural behaviour of concrete-filled hollow structural sections
Authors: Lu Yue Qing , Kennedy D. J. Laurie
Published: January 2010

In Standard CAN/CSA S16.1-M89, the contribution of the concrete to the flexural capacity of concrete-filled hollow structural sections is acknowledged as an alternative approach, but no method of assessing it is given. Preliminary studies had indicated that the concrete increased the ultimate moment capacity, the initial flexural stiffness, and the ductility, and delayed local buckling of the steel, thus enhancing the behaviour considerably. A series of four flexural tests on rectangular and square cold-formed hollow structural steel sections and twelve on concrete-filled sections were undertaken to assess the general behaviour of these composite sections. The test specimens were selected to examine the effects of different ratios of depth to width and therefore of the proportions of steel and concrete in compression, and of different values of shear span to depth as related to the transfer of forces from one to the other when no direct means is provided for this transfer. The tests showed that the ultimate flexural strength of the concrete-filled sections is increased by about 10–30% over that of the bare steel sections, depending on the relative proportions of steel and concrete. The stiffness is also enhanced. In all cases, slip between the steel and concrete was not detrimental, even though shear-span-to-depth ratios as low as 1 were tested. Models are developed to predict the flexural strength of the composite section. Fully plastic stress blocks with the concrete at its maximum strength are used. The models are in excellent agreement with the test results. Key words: composite beams, concrete-filled, flexural behaviour, hollow structural sections.
Travelling wave-induced liquefaction of sand deposits
Authors: Yang Q. S. , Poorooshasb H. B. , Cheung S. C. H.
Published: January 2010

The sea-floor deposit is assumed to be a saturated porous medium modelled by a two-phase system for which the coupled governing equations are derived from the theory of mixture. A constitutive model based on the generalized plasticity-bounding surface formulation is proposed to describe the soil behavior. An artificial boundary is suggested to deal with the unbounded domain problem. The coupled governing equations and the material model have been implemented into a nonlinear finite element program to analyze the travelling wave-induced liquefaction of seabed deposits. The results of two case studies are presented. The first case examines the response of sand deposit to the wave train at a site of underwater pipelines for nuclear power plants in Lake Ontario where the deposit was found to vary from loose to medium dense. The second case investigates the sea-floor behavior under a storm wave at the Ekofisk oil tank site in the North Sea where the deposit was reported to be dense. The results agree with the field observations. Key words: seabed instability, liquefaction, finite element, plasticity, sand, cyclic loading, travelling wave, unbounded domain.
Beam-column behaviour of steel tubes filled with high strength concrete
Authors: Prion Helmut G. L. , Boehme Jens
Published: January 2010

The results of an investigation into the behaviour of thin-walled steel tubes filled with high strength concrete are presented. The main emphasis is placed on the level of ductility that can be achieved, considering the fact that neither high strength concrete nor thin steel tubes are individually able to absorb significant amounts of energy under cyclic loading. Results of 26 tests on specimens with a diameter of 152 mm and a wall thickness of 1.7 mm, filled with concrete of characteristic compressive strength ranging between 73 and 92 MPa, are reported. Load combinations on the specimens range from pure axial compression, through various combinations of axial load and bending, to pure bending. Three specimens were subjected to cyclic loading. Test results are compared with design models that are used in current code specifications. Key words: steel tubes, concrete, composite, beam-column, beam, column, experimental.
Parametric study on noncomposite slab-on-girder bridges with enforced frictional contact
Authors: Lin Jian Jun , Beaulieu Denis , Fafard Mario
Published: January 2010

Using post-tensioned steel rods for strengthening noncomposite slab-on-steel girder bridges has the beneficial effects of both stabilizing the steel girders laterally and developing partial composite action longitudinally. The stabilizing effect and development of partial composite action are achieved by taking advantage of friction developed at the steel–concrete interface. A bridge reinforced by this technique is expected to have a higher load-carrying capacity and better load distribution under heavy traffic loads. Prestressed rods have been successfully used to strengthen 1/3 scale noncomposite bridge models in laboratory.The concrete slab-on-steel girder bridge models reinforced by prestressed rods are analyzed numerically in this paper by the use of the finite element method. Corresponding noncomposite models are also simulated for comparison to investigate the efficiency of this strengthening technique. The effects of variables such as the number of rods, prestressing level, type of load, slab thickness, steel girder slenderness, girder spacing, and ratio of radii of gyration of steel girders on the strengthening efficiency are studied by the finite element method. A full-scale bridge is analyzed to demonstrate the effect of the proposed reinforcing technique. Key words: bridge, composite action, contact, finite element, friction, parametric study, strengthening.
On earthquake-resistant reinforced concrete frame connections
Authors: Pantazopoulou S. J. , Bonacci J. F.
Published: January 2010

The behavior of earthquake-resistant reinforced concrete frame connections has been researched extensively over the past 30 years, but conflicting interpretations of the underlying physical problem and differences of opinion in defining acceptable performance criteria still pervade almost every aspect of connection behavior and design. This study explores the mechanics of reinforced concrete beam-column joints under lateral loads, with the aim to assess the parametric dependence of the behavior of these elements for the benefit of design. In the course of the study, published experimental information from around the world and results from a number of novel analytical studies are considered collectively in an attempt to broaden the scope and depth of the parametric description of joint mechanics. Apart from improved understanding of the physical problem, the most important outcome of this research is to formulate simple tools for design of earthquake-resisting beam-column connections using a consistent mechanics approach. Key words: beam-column connection, database, earthquake-resistant design, finite element analysis, reinforced concrete, shear strength, stirrups.
Évaluation expérimentale et renforcement des ponts en acier avec dalle de béton non participante
Authors: Dionne G. , Beaulieu D. , Picard A.
Published: January 2010

An experimental study was carried out to assess the stabilizing action of the friction between concrete slab and steel beams in noncomposite constructions. Slender beams, sensitive to lateral torsional buckling, were used in the experimental work. The results show that the friction is sufficient to prevent lateral torsional buckling of the steel beams. However, the flexural stiffness was not significantly increased so that friction alone is not sufficient to develop a composite action. To increase the frictional effect, the concrete slab was linked to the steel beams by two types of connectors. Additional tests were carried out to verify the efficiency of these connectors. Key words: steel bridges, lateral torsional buckling, composite action friction, reinforcement.
Insights from the Three Gorges study
Authors: Russell S. O. Denis
Published: January 2010

In the late 1980s, a consortium of Canadian engineering companies carried out a study of the proposed Three Gorges project on the Yangtze River in China. Probe International published a stinging critique of the proposed project and the study. The diverging conclusions from the two groups are explained by the fact that the Canadian engineering consortium and Probe represented two completely different cultures: the large dam, heavy civil engineering culture and the "new green culture." It is claimed that the best hope for avoiding similar conflicts over very large projects in future would be to include representatives from all the professional groups involved — environmental scientists, economists, sociologists, and civil engineers — as full members of the coordinating team for the project right from the beginning. Key words: Three Gorges project, large dams, environmental impact, flood control, hydroelectric.
Combined effect of repeated loads and low temperatures on asphalt pavements
Authors: Fang Yingwu , Sargious Michel
Published: January 2010

This research was undertaken to study the combined effect of repeated vehicle loads and low temperatures on the design thickness for both recycled and virgin asphalt pavements. It included three parts of work: theoretical analysis, laboratory tests, and computation. In the theoretical analysis, the finite layer method was used instead of the conventional layered theory to obtain the relationship between vehicle loads and the mechanical parameters in the pavement layers. In the laboratory tests, the behaviour of a recycled asphalt concrete mix consisting of 42% reclaimed and 58% new material was compared with that of a virgin asphalt concrete mix of similar characteristics. Finally, a computer program FPAVE was developed to determine the pavement thicknesses directly and conveniently. These thicknesses were then plotted in the form of curves for comparing the two types of pavements as well as for comparison with the thickness at 22 °C. Key words: asphalt pavement, fatigue, pavement design, recycling, temperature.
Towards a new base shear format in future NBCC seismic provisions
Authors: Heidebrecht A. C. , Naumoski N. , Rutenberg A.
Published: January 2010

Recent trends in the specifications of earthquake design forces are moving away from spectral amplification of ground motion towards direct evaluation of spectral values. Also, the 1988 Saguenay earthquake produced strong evidence for the need to modify the present provisions for low period structures in eastern North America. A new database consisting of 75 time histories was assembled and an extensive parametric study was undertaken to prepare new seismic response factors (S curves) for the National Building Code of Canada (NBCC). These time histories were divided into five categories (15 time histories each) on the basis of their frequency content as measured by their peak ground acceleration to peak ground velocity ratios, ranging from very high (≈3) to very low (≈0.5). Mean and mean + one standard deviation response spectra for one-degree-of-freedom and multi-degree-of-freedom systems were computed for the five categories using several normalizing (scaling) rules for the time histories. The results were compared and spectral amplification factors are presented. Spectra based on peak spectral velocity scaling were compared with spectra based on the present peak ground velocity scaling approach, and some differences are noted. Also, comparisons with the design spectra given in the 1991 edition of the National Earthquake Hazard Reduction Program provisions are presented. On the basis of this study, new S curves are proposed for consideration in the development of future editions of the NBCC. Key words: earthquake engineering, design spectra, building codes, amplification, ground motion, acceleration, velocity, ratio.
Reply: Hydrotechnical studies of Peter's River
Authors: Lye Leonard M. , Sharp James J.
Published: January 2010

not available
Discussion: Effect of construction cracks on the design of asphalt pavements
Authors: Phang Bill
Published: January 2010

not available
Reply: Effect of construction cracks on the design of asphalt pavements
Authors: Halim A. O. Abd El , Razaqpur A. G. , Kashef A. H. El
Published: January 2010

not available
Reply: Grouted anchorages for aramid fibre reinforced plastic prestressing tendons
Authors: McKay K. S. , Erki M. A.
Published: January 2010

not available
Small-scale experiments on ice-jam initiation in a curved channel
Authors: Urroz Gilberto E. , Ettema Robert
Published: January 2010

Two principal ice-jam initiation mechanisms, namely, lodgement and gorging, were identified through ice conveyance experiments in a small-scale, curved flume of rectangular cross section. Polyethylene blocks and beads were used to simulate ice fragments. Lodgement occurred for ice fragments that were large relative to channel width, while gorging took place when ice pieces were relatively small and were transported through the channel in multilayer. Channel roughness was found to have a significant effect in helping the arching mechanism that produces lodging. Maximum ice-floe concentration before jamming was found to increase linearly with Froude number, F, when gorging was dominant, but showed little dependence on F for ice jams initiated by lodging. Experiments conducted with point bars placed at the bends indicated that ice jams were initiated mainly by beaching of floes on the point bar. Maximum ice-floe concentration also increased linearly with Froude number for the point-bar experiments. Key words: ice-covered rivers, river bends.
Heuristic and simulation techniques for the scheduling of hazardous waste processing in an integrated treatment facility
Authors: Yundt P. E. , Baetz B. W. , Patry G. G.
Published: January 2010

The basic strategies for optimizing processing schedules of hazardous waste in an integrated hazardous waste treatment facility are analyzed. Five schedule optimization heuristics were evaluated on six simulation models of hypothetical integrated hazardous waste treatment facilities. The six models represented combinations of one of three unit process configurations and one of two facility operating policies. The heuristics were evaluated with respect to their ability to minimize the average completion time (makespan) of a specified set of jobs. The same five heuristics were applied to a model representing the physical and chemical treatment plant of the Alberta Special Waste Management Corporation. Operation under two operating policies for this case study was evaluated, and the results were compared with the hypothetical model results. Some heuristics were found to be capable of reducing makespans by 13–14% relative to the first in, first out heuristic. Key words: hazardous waste treatment, scheduling, heuristics, simulation modelling.
Correction factors for nonlinear runup and wave forces on a large cylinder
Authors: Isaacson Michael , Cheung Kwok Fai
Published: January 2010

A recently developed numerical method for second-order wave diffraction is summarized and is used to develop a simplified approach to predicting nonlinear runup and maximum wave loads for large coastal and offshore structures subjected to regular waves. The perturbation method on which the method is based is extended to provide correction factors for the runup and maximum loads. These correction factors apply directly to the predictions of linear diffraction theory, and are independent of the wave height. The correction factors for runup, maximum force and maximum overturning moment are provided for a range of geometric parameters relating to the case of a large circular cylinder extending from the seabed to the free surface. Nonlinear runup and load maxima calculated by the correction factors are compared with the results of previous experimental studies; in general, favourable agreement is obtained. An example application of the proposed procedure is provided, the importance of nonlinear effects in the evaluation of runup and wave loads is discussed, and the limitations of the results are indicated. Key words: coastal structures, diffraction, hydrodynamics, ocean engineering, offshore structures, wave runup, wave force, waves.
Test of selected bed-material load transport models: Nottawasaga River, Ontario
Authors: Chandler T. J. , Kostaschuk R. A.
Published: January 2010

Predictions from 13 bed-material load sediment transport models are compared with 19 measurements of bed-material transport in Nottawasaga River, Ontario, using summary plots and geometric statistics. Model selection is based on recent engineering application and suitability for the flow and sediment conditions of the river. The models of Laursen (1958) and Yang (1979) perform best, followed by those of Ackers and White (1973). The models of Van Rijn (1984), Maddock (1976), Karim and Kennedy (1983), Brownlie (1981), and Yang (1973) have considerable data scatter. The models of Engelund and Hansen (1967) and Shen and Hung (1972) are the poorest predictors. Poor model performance is primarily due to overestimation of flow strength needed for particle entrainment and an excessively steep slope in the relations between flow strength and sediment transport. Key words: bed-material load transport models, test, Nottawasaga River.
Utilization of partial end restraint in bridge strengthening
Authors: Klaiber F. Wayne , Wipf Terry J. , Abu-Kishk Rula B.
Published: January 2010

The purpose of this investigation is to determine a technique for increasing the capacity of bridges to accommodate today's increase in loading. Strengthening existing steel stringers in composite, steel-beam, concrete-deck bridges by providing partial end restraint is shown to be feasible. The research program included a review of existing literature, testing of a full-scale bridge beam and a 1/3-scale bridge model, and finite-element analyses of the restraint brackets, the test beam, and the model bridge. Analytical and experimental results of this investigation are presented, as well as results from an analytical investigation of the bridge model when subjected to various degrees of end restraint. Six different degrees of end restraint were examined. The achieved percent reductions ranged from 12% to 26% for midspan strains, 20% to 30% for midspan deflections, and 10% to 32% for beam end rotations. The correlation between the analytical and experimental results verified the basic design assumptions; thus, the analytical models can be used for determining the location and the degree of end restraint required to strengthen an existing bridge. Key words: bridges, girder, composite structures, tests, models, strengthening, rehabilitation, restraint.
Statistical analyses of compacted clay landfill liners. Part 1: model development
Authors: Donald Scott B. , McBean Edward A.
Published: January 2010

The acceptance of compacted clay liners, from a management point of view, has been a source of major concern because of the uncertainty associated with the hydrogeologic properties of the clay. By examining the flux of leachate through the compacted clay liner of a typical engineered landfill, where the hydraulic conductivity of the clay is represented by a stochastic process, an acceptance protocol suitable for compacted clay landfill liners is derived. Determination of the equivalent hydraulic conductivity of the clay liner is accomplished by comparing the flux of leachate through a homogeneous representation of the clay with the flux obtained by Monte Carlo analyses. Acceptance criteria are subsequently developed based on a statistical technique which calculates the confidence limits about a percentile of a probability distribution as well as about the mean of the distribution. For the landfill configuration simulated, the results indicate that the hydraulic conductivity of a compacted clay landfill liner follows a lognormal distribution and exhibits virtually no spatial correlation structure. In addition, for liners exhibiting a geometric mean conductivity of 10−7 cm/s and a standard deviation of 0.3, the geometric mean value is a conservative estimate of the hydraulic conductivity of the clay, provided the liner is constructed in a series of four 150 mm lifts. Key words: clay liners, hydraulic conductivity, statistical analyses, latin hypercube, equivalent hydraulic conductivity.
Efficiency evaluation of an installed swirl separator
Authors: Villeneuve Jean-Pierre , Gaume Eric , Michaud France
Published: January 2010

Municipalities try to limit overflow of their sewer systems by various technologies such as storage in basins and transfer of the water after the storm to a treatment facility, storage and decantation, on-line treatment of overflows, or by alternative technologies like porous roadways or runoff infiltration. The swirl separator, proposed by the American Public Work Association, is an attractive device, because it requires little supervision and maintenance. However, only few results exist about its efficiency for treating combined sewer overflow. The purpose of the present field study was to determine the performance of an existing device (the Québec swirl regulator). The results, presented herein, show that up to 25% of the suspended solids transported during storms can be eliminated, but most of the liquid–solid separation seems to take place in the upstream collecting pipe. Key words: combined sewers, overflows, water treatment, suspended sediments.
A pragmatic approach to using resource loading, production, and learning curves on construction projects
Authors: Wideman R. Max
Published: January 2010

The purpose of this paper is to present some rules of thumb, based on experience, for the early planning of new civil and building construction work. In such construction, resource input (men, materials, equipment, etc.) is varied according to the planned timing and availability of the work. On a well-run site, this resource loading as well as its consequent output follows a distinctive pattern within relatively narrow limits for the whole of the job. Practical considerations of why this should be so are presented.Based on experience, this paper suggests first approximation profiles for both typical resource loading and progress S-curves and shows that the difference could be due to the effects of learning. The basis for calculating the shape of the learning curve and how the application of this concept is limited on a construction site are described. The manner in which an alternative learning curve calculation can be more useful in tracking progress is demonstrated. The significance of these profiles and their relationships for improved planning and tracking of new construction work is suggested. An example of the output from a less well managed project as compared to the planned S-curve is also included. Key words: learning curve, productivity improvement, progress (production) curve, resource loading.
Micro-fiber reinforced cement composites. I. Uniaxial tensile response
Authors: Banthia N. , Moncef A. , Chokri K. , Sheng J.
Published: January 2010

Stress–strain curves in uniaxial tension were obtained for micro-fiber reinforced cement composites reinforced with high volume fractions of carbon, steel, and polypropylene fibers both in the mono and hybrid (combination) forms. Considerable strengthening, toughening, and stiffening of the host matrix due to micro-fiber reinforcement was observed. In the hybrid fiber composites, different fibers appear to act as additive phases, i.e., they maintain their individual reinforcing capabilities. The composites were also impact tested in uniaxial tension using a newly designed instrumented impact machine. When compared with static test results, considerable sensitivity to stress-rate was noted; composites were found to be stronger and tougher under impact and the improvements were more pronounced at higher fiber volume fractions. The paper recognizes the potential of these composites for use in thin sheet products and other similar applications, and stresses the need for continued research. In Part II of this paper, these composites will be characterized under an applied flexural load and a fracture criterion will be developed through crack growth tests. Key words: fiber reinforced cements, tension, strength, ductility, impact.
A reliability programming model for hydropower optimization
Authors: Srinivasan Rangarajan , Simonovic Slobodan P.
Published: January 2010

A new reliability model for planning the operation of a multipurpose reservoir for hydropower generation and flood control, which considers the stochastic nature of inflows, is presented. The proposed solution algorithm maximizes the benefits accrued from hydropower generation and minimizes the economic losses incurred due to the reservoir not meeting the required reliabilities for hydropower supply and flood control. This algorithm uses a linearization technique to approximate the nonlinear energy function. An original method of incorporating the energy generation in the formulation of the reliability programming model is presented. This model determines the optimal reservoir release policy along with the optimal reliabilities of satisfying the hydropower demand and providing the required flood control storage. Applicability of the model is demonstrated using Manitoba Hydro data. Key words: reservoir planning, midterm planning, flood control, hydropower, stochastic modeling, reliability, risk-loss.
Research on low and high speed hovercraft icebreaking
Authors: Hinchey Michael , Colbourne Bruce
Published: January 2010

Operational experience in Canada during the early seventies showed that hovercraft can make very effective icebreakers. In a low speed mode, the hovercraft causes an air cavity to form under the sheet as it rides onto it. This causes a section of the sheet to become unsupported and fail in bending under the action of its own weight. In a high speed mode, the motion of the craft over the sheet sets up large amplitude flexural gravity waves. Research into both modes of operation has been going on at Memorial University of Newfoundland (MUN) since the mid-eighties. This paper summarizes this work. For the low speed case, scaling laws for the resistance to forward motion of two new geometries were developed and confirmed with data obtained in the ice tank at the Institute for Marine Dynamics (IMD) in Newfoundland. For the high speed case, measurements of sheet deflections in the MUN wave tank and the IMD ice tank showed that a critical speed exists for motion over a sheet. At this speed, sheet deflections are limited only by dissipation and nonlinearities. We believe this critical speed is the source of high speed mode hovercraft icebreaking. Key words: hovercraft, icebreakers, air cavity mode, wave mode.
Design of horizontally curved composite box-girder bridges: a simplified approach
Authors: Cheung M. S. , Foo S. H. C.
Published: January 2010

Because of their excellent torsional capacity, box girders are used extensively in modern bridge construction having curved alignments. Applications of most design codes have been limited to bridges where the radius of curvature is much greater than the span length and cross-sectional dimensions. To meet the practical requirements arising during the design process, simple design methods are needed for curved bridges. This paper presents the results of a parametric study on the relative behaviour of curved and straight box-girder bridges and on the development of a simplified design method for the combined longitudinal moment of curved bridges. The combined moment includes the effects of flexure, torsion, and distortion. Three simply supported concrete-steel composite bridge models, including single-cell, twin-cell, and three-cell box girders and subjected to loadings as specified in the Ontario Highway Bridge Design Code, were analyzed using the finite strip method. The parameters considered in the study include types of cross section; types, locations, and magnitudes of loads; span lengths; and radius of curvature. Preliminary analysis of the results suggests that the behaviour of horizontally curved box-girder bridges is dependent on a variety of parameters, but most importantly on the span-to-radius ratio. Empirical relationships for combined longitudinal moment between curved and straight box-girder bridges are also proposed. Key words: bridge, curved, composite, design, finite strip.
Guidelines for the seismic evaluation of existing buildings
Authors: Allen D. E. , Rainer J. H.
Published: January 2010

Because of the difficulties in applying current earthquake requirements in the National Building Code of Canada to existing buildings, a document "Guidelines for the seismic evaluation of existing buildings" has been developed to provide alternative criteria. The Guidelines are based primarily on similar U.S. documents with changes to suit Canadian seismicity and practice. The basis of the document is earthquake damage experience as it relates to life safety, and the methodology is based on the identification of deficiencies of the building from a master list known from earthquake experience to result in life-threatening failures. Potential deficiencies are checked against evaluation criteria which are based on the NBC/CSA seismic limit states design using a load reduction factor of 0.6. The paper provides a background on those features which differ substantially from the NBC requirements. Key words: existing buildings, seismic evaluation, procedure, criteria.
Deck slabs of skew girder bridges
Authors: Bakht Baidar , Agarwal Akhilesh C.
Published: January 2010

Canadian codes allow the design of concrete deck slabs of slab-on-girder bridges by taking account of the internal arching action that develops in these slabs under concentrated wheel loads in particular. Provided that certain prescribed conditions are met, a deck slab is deemed to have met the design criteria if it is provided with a top and a bottom layer of steel reinforcement with each layer consisting of an orthogonal mesh of steel bars in which the area of cross section of the bars in each direction is at least 0.3% of the effective area of cross section of the deck slab. For deck slabs of bridges having skew angles greater than 20°, the codes require the minimum amount of reinforcement to be doubled in the end zones near the skew supports. Model testing has shown that need for such an increase can be eliminated by providing composite end diaphragms with high flexural rigidity in the horizontal plane. The proposed concept is tested on a model of fibre-reinforced concrete deck without steel reinforcement in which deficiencies in the confinement of the deck slab readily manifest themselves in form of a bending, rather than punching shear, failure. Key words: highway bridges, bridge decks, deck slabs, skew deck, skew bridges, fibre-reinforced concrete decks.
Modelling of continuous crushing of ice in front of offshore structures
Authors: Brown T. G. , Morsy U. A.
Published: January 2010

A one-dimensional finite element is developed to represent the continuous crushing and extrusion of ice in interactions with offshore structures. The element is developed with the objective of providing a model for the analysis of dynamic ice–structure interactions in which both nonsimultaneous and phase-locked behaviours occur. The element has two components: one to model the damage accumulation in intact ice and one to model the extrusion of pulverized ice between the intact ice and the structure. The intact but damaging ice behaviour is based on a rate theory approach to crack density and damaged material compliance which is a function of stress and damage. The extrusion component models a viscous-plastic material which is modelled using a Tresca failure criterion and viscous flow. The element is developed as part of an existing finite element package (Abaqus) through its user material and user element capabilities. The paper describes in detail the development and implementation of the element and presents sample results of its performance in continuous crushing interactions with a rigid structure. The results show that the element can be used as the interface between moving intact ice sheets and offshore structures modelled using the finite element method. Key words: ice, structures, dynamics, finite elements, rheology.
Culvert inlet efficiency
Authors: Smith C. D. , Oak A. G.
Published: January 2010

The results of experimental work carried out on culvert inlet efficiency at the University of Saskatchewan are reported in this paper. Efficiency is reported in terms of coefficient of discharge when the culvert operates with inlet control, and in terms of the coefficient of entrance loss when the culvert operates with outlet control. A larger coefficient of discharge or a smaller coefficient of entrance loss represents a higher efficiency. Seven different culvert inlets were tested for both inlet and outlet control, and for the headwater level both above and below the elevation of the crown of the pipe at the inlet. The results are reported in nondimensional charts. Key words: culvert flow, inlet control, outlet control, efficiency, head losses, capacity.
Confined capping system for compressive strength testing of high performance concrete cylinders
Authors: Johnson Claude D. , Mirza S. Ali
Published: January 2010

This paper presents a simple, inexpensive confined cap testing method which can be employed in the compressive strength testing of high performance concrete cylinders. An inexpensive customized cylinder capping apparatus and standard concrete laboratory testing equipment are employed. The paper describes the capping apparatus, capping and testing procedures, as well as test results for concrete compressive strengths up to and exceeding 100 MPa. Key words: capping, capping confinement, compressive strength, cylinders, end condition, grinding, high-strength concrete, specimen size, testing.
Numerical simulation of concrete expansion in concrete dams affected by alkali–aggregate reaction: state-of-the-art
Authors: Léger P. , Tinawi R. , Mounzer N.
Published: January 2010

Many concrete dams and other concrete structures in Canada, and throughout the world, are suffering from deteriorations induced by alkali–aggregate reaction (AAR) that impair the durability and serviceability, and might also affect, in the long term, the safety of the installation. Alkali–aggregate reaction produces concrete expansion, and generally leads to a loss of strength and stiffness (cracking), and generates undesirable deformations and disturbances in the equilibrium of internal forces. The expansion mechanisms in concrete affected by AAR are complex and influenced by a number of factors that are difficult to quantify. Nevertheless, advanced numerical simulation models are generally used in close conjunction with field monitoring of displacements to assist in the structural evaluation and rehabilitation of dams where AAR has been identified. A review of the physical processes that control the structural behaviour of concrete dams suffering from AAR, and numerical simulation procedures to represent AAR concrete expansion by the finite element method, is presented herein. The present state of knowledge to simulate the AAR expansion process has been found to be limited and not yet satisfactorily developed. A methodology to distribute the observed concrete expansion in proportion to the compressive stress state, temperature, moisture, and the reactivity of the concrete constituents is proposed in this paper as a first step to rationalize the numerical modelling of the AAR concrete swelling process in concrete dams. Key words: alkali–aggregate reaction, concrete dams, finite element method, dam safety.
Construction de la digue nord de l'aménagement La Grande
Authors: Massiéra Michel , Levay Jerry
Published: January 2010

LG-1 hydroelectric project, part of La Grande Complex in northern Quebec, required the construction of a 2444 m long dyke on the north bank. The presence of sensitive marine clay, with deltaic and river sand and silt deposits on top of the clay in the central terrace, called for special design features. These included the construction of a dyke with side berms in a depression to ensure stability and the construction of a cement–bentonite cutoff through the sand and silt deposits of the terrace. This paper describes the different phases of dyke construction with emphasis on foundation treatment and construction techniques. Key words: bentonite, cement, clay, construction, cutoff, dyke, excavation, foundation, slurry, trench.
Bolted glass-fibre-reinforced plastic joints
Authors: Erki M. A.
Published: January 2010

Test results are presented for single fastener glass-fibre-reinforced plastic (GFRP) members connected with GFRP threaded rods, steel threaded rods, and steel bolts. Twenty-eight joints were tested in tension and thirty-five were tested in compression. For some of the tests, a GFRP pipe was used as a protective sleeve for the threads of the steel and GFRP threaded rods. The effect of fastener strength and stiffness on the load carrying capacity of the joints is reported. The major findings for both the tension and compression tests were that joints constructed with a GFRP threaded rod had approximately half the strength of joints constructed with a steel threaded rod. Also, joints constructed with a GFRP threaded rod and GFRP pipe sleeve were at least a third stronger than joints constructed with a GFRP threaded rod alone. The GFRP members used consisted of a pultruded glass fibre sheet, which was composed of symmetrically stacked, alternating layers of identically orientated unidirectional E-glass fibres and randomly orientated E-glass continuous strand mat. The maximum load carrying capacity decreased with increasing angle of loading with respect to the unidirectional fibres, but this was more pronounced for the tension tests than for the compression tests. For the tests performed, it was sufficient to finger tighten end nuts; indeed, tightening end nuts by a half turn-of-the-nut slightly decreased the strength of the joints. Key words: glass-fibre-reinforced plastic, connections, fibreglass bolts, experimental.
Behaviour of bolted link-column joints in eccentrically braced frames
Authors: Ramadan T. , Ghobarah A.
Published: January 2010

Current seismic provisions require that shear links in eccentrically braced frames be fully welded to the column flanges at the link-column joint. Since field welding may have its disadvantages, the use of bolted extended end-plate connection is examined. An experimental program is conducted to assess the response of extended end-plate connections of link-column joints in eccentrically braced frames. Six link-column joint specimens are tested using a cyclic load that represents the severe load reversals that the frame may be subjected to during strong earthquakes. The specimens are selected on the basis of different connection designs. Measurements of forces, strains, and displacements are made. Interaction curves relating the shear force and moment acting on links with semirigid connections are developed. The slip tendency and energy dissipation capacity of the different specimens are compared. On the basis of the test results, a design procedure is developed for the bolted extended end-plate link-column connection. It is concluded that bolted extended end-plate connections can be used for link-column joints of eccentrically braced frames. In properly designed connections bolt slippage was not measured even at high shear forces that are characteristic of link-column joint. Existing guidelines for the design of extended end-plate link-column joints are modified to account for the variable shear force and moment associated with links of different lengths. Key words: steel, frame, eccentric, braced, bolted, end plate, link, connection.
Numerical analysis of face-shell bedded hollow masonry walls subject to concentrated loads
Authors: Sayed-Ahmed Ezzeldin Y. , Shrive Nigel G.
Published: January 2010

A nonlinear elastoplastic finite element model has been developed for face-shell bedded hollow masonry walls subject to in-plane concentrated loads. The model takes into account geometric and material nonlinearities as well as damage due to progressive cracking. Behaviour of the masonry components subject to compressive states of stress is modelled using the theory of plasticity, and cracking is modelled using both discrete and smeared cracking approaches. The model is generated on a SUN SPARC 10/31 workstation using the preprocessor of the finite element program ANSYS; the finite element solution is obtained using the ABAQUS program on the Fujitsu VPX 240/10 and IBM RS/6000 workstation. A brief summary of the numerical modelling and the iterative procedures is discussed. Results from simulated tests of seven-course high wallettes subject to concentrated loads are used to verify the behaviour of the numerical analyses. The methodology, when combined with substructuring, allows analysis of substantially larger walls than would more typical 3-D analyses. The model can be used to check existing design rules and develop more rational design methods for hollow masonry subject to concentrated load. Key words: masonry, hollow concrete masonry, finite element modelling, cracking, failure, strength enhancement factor, concentrated loads.
Linear regression analyses with censored data: estimation of PAH washout ratios and dry deposition velocities to a snow surface
Authors: Sharma Mukesh , Thomson Neil R. , McBean Edward A.
Published: January 2010

Detection limits of analyzing instruments are the main reason for censored observations of pollutant concentrations. An iterative least squares method for regression analyses is developed to suit the doubly censored data commonly observed in environmental engineering. The modified iterative least squares method utilizes the expected values of censored observations estimated from the probability density function of doubly censored data in a regression process. The modified method is examined for bias in the estimation of the parameters of a linear model, and in the estimation of the standard deviation of the regression. A mechanistic model for atmospheric transport and deposition of polycyclic aromatic hydrocarbons (PAHs) to a snow surface is formulated by utilizing the long-term PAH retention property of deep snowpacks. The modified iterative least squares method is applied to estimate the deposition parameters (dry deposition velocity and washout ratio) for various PAH species, since some of the PAH deposition levels were below the minimum detection limit of the analyzing instrument. The estimated parameters are examined statistically, and compare favourably with previously reported estimates of these parameters. Key words: censored data, regression, iterative least squares, PAHs, dry deposition velocity, washout ratio.
The impact of El Nino southern oscillation on central Canadian floods and droughts
Authors: Gingras Denis , Adamowski Kaz
Published: January 2010

A comparison of flood and low flow magnitudes during periods of El Nino and outside those periods led to the conclusion that flood risk in central Canada is not constant from year to year. This finding has implications for water resources management, particularly flood forecasting and reservoir operation. Key words: flood risk, water resources management, climate change.
A practical method for incorporating flexible connections in plane frame analysis
Authors: Lo D. S. K. , Stiemer S. F.
Published: January 2010

A practical method for incorporating realistic flexible connections in plane frame analysis, including the effect of connection sizes and shear deflection, is presented. The general algorithm can be easily implemented in a standard plane frame analysis program and, once implemented, it can be an ideal tool for production work in the steel industry. Connection stiffness is programmed directly into the analysis using the moment–rotation equations developed by Frye and Morris or may be entered separately as data. Practical application of this method of analysis is demonstrated by modifying a standard plane frame analysis program to include the effect of flexible connections. Solutions obtained using this modified program, CPlane, were verified against the findings of Moncarz and Gerstle. A simple plane frame structure was analyzed under various lateral load intensities for different connection assumptions. It was found that the inclusion of connection behavior significantly altered the internal force distribution and design of the structure. Key words: connections, matrix frame analysis, moment–rotation relations.