bluuebunny/crossref_metadata_2025 huggingface dataset:
Some implications of the new speed–volume curves to highway user cost and sizing of roads
Authors: Sharma Satish C. , Tayebali Akhtarhusein , Soliman Afifi H.
Published: January 2010

This paper investigates some implications of the speed–volume relationships for two-lane rural highways as proposed in the new edition of the U.S. Highway Capacity Manual, which is expected to be completed soon. The effect of the new speed–volume curves on road user costs is analysed by considering the case of Alberta Transportation. The analysis carried out in this paper indicates that the new speed–volume curves, when employed with the traditional values of other variables, such as vehicle running costs and value of travel time, produce cost–volume relationships that might appear unacceptable from both the highway agencies' and the road users' perspective. To overcome such a limitation it is suggested that a cost of comfort and convenience should be computed and added to the user cost.Basing their proposal on a survey of Alberta households and the actual practice of road sizing by Alberta Transportation, the authors present a generalized mathematical model to estimate the cost of comfort and convenience. The structure of the model and its independent variables include the considerations of (a) the relative importance of driving comfort as perceived by road users, (b) the unsatisfied demand (overtaking demand minus actual overtaking) curve, (c) the type of road use, (d) volume-to-capacity ratio, (e) desired highway speed, and (f) vehicle classification. The paper discusses and demonstrates how this model can be calibrated and used for economic analysis for designing and upgrading of rural highways. Key words: transportation, highway economic analysis, road user costs, cost of comfort, speed–volume curves, highway design.
Linear stochastic optimization applied to biochemical oxygen demand – dissolved oxygen modelling
Authors: Burn Donald H. , McBean Edward A.
Published: January 2010

A methodology for reflecting stochastic considerations in an optimization model is presented. The technique, which uses chance-constrained programming, is applied to a water quality management problem wherein concern is with the interaction between biochemical oxygen demand (BOD) and the dissolved oxygen (DO) concentration in a river. The uncertainty in the problem is considered to be embodied in transfer coefficients for which a lognormal distribution is derived from moment estimates provided by first-order uncertainty analysis. The appropriateness of the lognormal distribution is confirmed by results from a simulation modelling exercise. Key words: water quality, optimization, uncertainty, mathematical modelling.
Finite element analysis of cracked and uncracked tubular T-joint
Authors: Bhuyan G. S. , Arockiasamy M. , Munaswamy K. , Vosikovsky O.
Published: January 2010

A welded tubular T-joint is analysed using finite element methods to obtain through-thickness and surface stresses due to axial and in-plane bending loads. The effects of a shallow weld toe crack on the stress redistribution are studied. The two-dimensional analysis of the joint includes the membrane stiffness representation by plane stress element and the flexural stiffness by plate bending element. For the three-dimensional analyses, the joint is modelled using incompatible solid elements to improve flexural characteristics. The embedded elliptical crack front is modelled by straight-line segments. The region at the vicinity of the crack is discretized using special elements, which produce a singular stress field at the crack front. Key words: tubular joint, stress analysis, weld toe crack, incompatible element, singular element.
Dynamic behaviour of a gymnasium floor
Authors: Rainer J. H. , Swallow J. C.
Published: January 2010

Ten mode shapes, natural frequencies, and modal damping values have been measured for a steel-joist concrete-slab floor spanning 32.1 m. From ambient vibrations and steady-state shaker tests the frequency of the fundamental mode was determined to be 3.5 Hz, and the modal damping ratio to be approximately 1% of critical. A comparison of vibration criteria in Appendix G of CAN3-S16.1-M84 confirms satisfactory performance for walking, but for other rhythmic exercises disturbing vibrations developed. These occurred primarily at the forcing frequency of the exercises and not at floor resonance frequencies. Values of dynamic load factors, α, for rhythmic loadings of this floor were evaluated in accordance with the guidelines on floor vibrations in the Commentary to the National Building Code of Canada 1985. Key words: floors, gymnasiums, vibration tests, resonant frequencies, mode shapes, dynamic loads, dynamic response.
Shear-moment transfer in flat plates
Authors: Simmonds Sidney H. , Doblanko Brian W.
Published: January 2010

For many concrete slabs without beams, the critical design factor is the shear stress in the vicinity of the column–slab junction. This is particularly so near edge and corner columns where the shear stresses due to the unbalanced moments may account for the major portion of these stresses. The determination of these design stresses in accordance with the provisions of Standard CAN3-A23.3-M84 is both time consuming and subject to numerical mistakes. Based on these provisions, design charts were developed, which greatly reduce the amount of calculation required and are suitable for routine use in the design of slabs. The use of the charts is illustrated by examples. Key words: design, flat plate, moment transfer, reinforced concrete, shear, slabs.
RIVER4: a program for flow profile computation
Authors: Smith Alan A. , Ashenhurst Paul B.
Published: January 2010

The paper describes a relatively easy to use computer program for the analysis of steady state surface and energy profiles in networks of open channels. RIVER4 is intended primarily for use in a time-sharing environment to facilitate the trial and error setup and calibration and modification of networks of arbitrary geometry and connectivity. The networks may consist of natural and man-made open channels or sewer systems or both, in configurations of single reach, multiple tributaries, and bifurcated branches with resultant "island" flow. As well as regular reaches, the system description may include transition devices such as bridges, weirs, culverts, manholes, and diversion structures. The flow resistance equation is selected at run time, from six commonly used laws. System geometry is stored on secondary devices such as tapes or discs so that relatively large systems may be analysed in machines of modest size. Key words: backwater, channel, computer, design, flood, islands, networks, profiles, sewers.
Excess biological phosphorus removal in the activated sludge process using primary sludge fermentation
Authors: Rabinowitz B. , Oldham W. K.
Published: January 2010

This paper examines the role of short-chain volatile fatty acids in the excess biological phosphorus removal mechanism of the activated sludge process. The effectiveness of various substrate additions in inducing phosphorus removal was investigated through a series of laboratory and pilot-scale experiments. Phosphorus release and substrate uptake both take place in the anaerobic zone of the process and there appears to be an exchange phenomenon that occurs between the two molecules. The system phosphorus removal of the process is improved by the addition of sodium acetate to the anaerobic zone. It is important that the zone receives no incoming nitrate, as the added substrate will be oxidized in the denitrification reaction, rendering it unavailable for the phosphorus removal mechanism. Acetate and propionate, the two substrates that are most effective in inducing anaerobic phosphorus release, can be generated on-site at a treatment plant by primary sludge fermentation in concentrations sufficient to significantly enhance the phosphorus removal characteristics of the process. Key words: biological phosphorus removal, short-chain volatile fatty acids, phosphorus release, substrate utilization, primary sludge fermentation.
A note on the stabilities of work trip travel demands in Toronto
Authors: Hutchinson B. G.
Published: January 2010

The 1971 and 1981 census journey-to-work data are used to examine the temporal and spatial stabilities of home-based work trip travel demands in the Toronto census metropolitan area (CMA). Regression analysis is used to establish consistent trip generation equations at the census tract level using population, household, and dwelling unit data; the stabilities of alternative equations over time are examined. All of the partial regression coefficients shifted over time, reflecting the substantial changes that have occurred in household structure, female labour force participation, and the characteristics of the housing market. The spatial distributions of the residuals are examined in terms of the spatial differentiation that exists in the household sector in the Toronto CMA in terms of variables such as household size, population age, and occupation status. The use of traditional trip generation techniques is difficult to sustain given the temporal and spatial variations in the trip generation rate. It is concluded that travel demands can only be estimated from a careful consideration of the residential dynamics of the major subareas in a region.
Truck braking distance and speed estimates
Authors: Navin Francis P. D.
Published: January 2010

The most frequently cited cause of truck accidents is “speed too fast for prevailing conditions.” To cite this cause, a speed estimate is necessary. This paper shows the factors that should be considered. The factors most useful in estimating a truck's braking capability include vehicle configuration, loading, location of the centre of mass, and axles with brakes. The exact value of some of the variables is difficult to obtain.The formulation proposed in this paper builds on a simple and effective procedure used by police agencies to estimate speed from skid marks. The formula given by R. Rivers' “Traffic accident investigator's handbook” is formalized and the elements in his correction factor N are derived. Basic equations for the braking of straight trucks and combinations are derived. The difficulty of implementing the equations in practice for all but the simplest situation is obvious from the complexity of the equations. A lumping of all the parameters into a simplified form is developed based on truck stopping distances obtained from published experimental data. All the trucks in the data had well-adjusted brakes. The final equation to estimate speed from a truck's skid marks accounts for the average ability of such vehicles to stop as well as the variance in stopping ability. Key words: truck braking, braking efficiency, stopping sight distance, skid marks.
Anaerobic treatment of high-sulfate wastes
Authors: Oleszkiewicz Jan A. , Hilton Barry L.
Published: January 2010

Six parallel upflow anaerobic sludge bed reactors were operated at chemical oxygen demand (COD) loads from 3 to 10 kg COD/(m3∙d). Four reactors (R1–R4) were fed sodium sulfate at loads of 1–3 kg S-SO4/(m3∙d). Reactors R1 and R2 were fed spent cheese whey with R1 being operated in an unstripped and R2 in a stripped mode. At COD loads below 5 kg/(m3∙d), the removal in R1 was 60–80% COD and generally trailed R2 by a margin of 0–15%. At higher COD loads and at higher SO4/COD ratios, the performance of R1 deteriorated significantly. A similar situation was found in the pair R3 (unstripped) and R4 (stripped), which was fed a mixture of spent whey and sulfite cooking liquor. Reactors R5 and R6 were subjected to the same feed as R3 and R4, but no sulfate was added. A comparison of R4 with R6 indicated slightly lower COD removal in R4 with similar amounts of volatile fatty acids accumulating in both reactors in cases of overloading. Key words: anaerobic treatment, sulfides, methanogenesis, inhibition, sludge bed reactor, dairy wastes, pulp and paper wastes, sulfate reduction.
Design examples for HSS trusses
Authors: Packer Jeffrey A.
Published: January 2010

Following recent international consensus on a series of complex design formulae for the static strength of welded joints in hollow structural section (HSS) trusses, design aids and design procedures compatible with CAN3-S16.1-M84 and based on these recommendations have been produced for implementation in Canada. This paper formally illustrates the use of these design aids by undertaking design examples for rectangular hollow section (RHS) chord planar trusses. The design aids discussed by the writer are in the form of charts for manual design and an interactive microcomputer program for automated truss design. Although the design method is much more rigorous than that presently used by Canadian structural engineers, who typically follow the guidelines of the Stelco HSS connections manuals, it vividly illustrates to the user the principal parameters affecting the strength of welded joints in HSS trusses. The paper also demonstrates that the joint strength criteria frequently control the selection of members, thereby making the design and checking of such joints the responsibility of the design engineer rather than the fabricator. Key words: hollow structural sections, tubes, welded joints, trusses, limit states design, design aids.
Structural design and seismic qualification of extra high voltage disconnect switch
Authors: Kar R.
Published: January 2010

This paper describes the structural design approach and the method of seismic qualification for an extra high voltage disconnect switch, a vital component in the substations of a power system network. Shaping and sizing of porcelain members of the frame received special attention to enhance their resistance to earthquake. A carefully developed finite element model, on analysis by response spectrum and time-history methods, showed acceptable seismic performance and an adequate margin of safety. Shake table tests for seismic qualification, called for by the specification, were not feasible owing to the large dimensions of the complete assembly. The alternative approach was to perform in situ modal tests. By exciting the structure with a random force through a portable hydraulic exciter and using accelerometers to record the structural response, the dynamic characteristics of the equipment — the frequencies, mode shapes, and damping — were determined. Correlation between the results of finite element analysis and experimental modal analysis confirmed the validity of the analytical model. Application of combined analysis and testing for seismic qualification is demonstrated by a case study on an 800 kV disconnect switch.
L'écoulement dans des déversoirs latéraux
Authors: Hager Willi H.
Published: January 2010

The main flow characteristics of side weirs are presented. In particular, the discussion accounts for the dynamic effects on the lateral outflow intensity, the additional head losses due to the lateral and the frictional effects on the free surface profile. The pseudouniform flow condition is considered in detail. Using typical nondimensional parameters, the general solution for the free surface profiles and the local discharge distribution is presented graphically. The computational procedure is illustrated by examples. Key words: hydraulics, side weir, open channel flow, water distribution, bifurcation.
Lessons from the 1985 Mexican earthquake
Authors: Mitchell Denis , Adams John , DeVall Ronald H. , Lo Robert C. , Weichert Dieter
Published: January 2010

Severe damage during the September 19, 1985 Mexican earthquake prompted a site visit by three engineers and two seismologists representing the Canadian National Committee on Earthquake Engineering. This paper includes background information on earthquake history of the region, details of the 1985 earthquake and its strong ground motion, subsoil conditions, and building code provisions. The team's observations of moderate damage in the epicentral area are consistent with the relatively low near-field accelerations (15% g). In the damaged parts of Mexico City, soft soil conditions amplified the ground motion and resulted in almost pure harmonic motion with a period of about 2 s. These characteristics, together with the long duration and high accelerations (20% g) caused severe damage to many structures, as is illustrated in the paper. Lessons learned from the earthquake together with the Mexican emergency code changes are discussed. Key words: seismic, earthquake, Mexico, soils, structures, codes.
Construction de l'évacuateur de crues Opinaca
Authors: Massiéra Michel
Published: January 2010

The Opinaca spillway is one of the concrete structures of the EOL (Eastmain – Opinaca – La Grande) project within the "La Grande" hydroelectric complex at James Bay, Quebec. Three rivers were diverted to the La Grande River to increase the hydroelectric potential of the LG 2 power plant. Opinaca spillway is a reinforced concrete structure 28.7 m wide and 46.6 m long with intake and restitution channels excavated in the rock. This paper describes the different construction phases of the spillway with emphasis on rock excavation and support, grouting, concreting, and quality control. Key words: blasting, bolting, concreting, dowel, excavation, grouting, presplitting, rock, shotcrete, spillway.
Seismic ground-motion computations at low probabilities
Authors: Milne W. G. , Weichert D. H.
Published: January 2010

The seismic provisions for the National Building Code of Canada are based on assumptions that seismic source zones can be defined within which earthquakes are distributed uniformly according to a magnitude/frequency-of-occurrence relation, and that a set of attenuation relationships hold for the earthquake magnitudes and distances that dominate the selected risk level of 10% probability of exceedence in 50 years. These assumptions appear to be reasonable at the probability level used for the average structures included in the code. However, attempts of extending the calculations to significantly lower levels of probability for special structures may invalidate the original assumptions, because the dominant contribution ranges of magnitudes and distances are outside of the intended scope of the ground-motion relations. Moreover, the basic assumption that earthquakes are uniformly distributed over large source zones is seriously compromised.
Impact of urbanization on hydrologic response of a small Ontario watershed
Authors: Cook D. J. , Dickinson W. T.
Published: January 2010

The Speedvale Experimental Basin, a 210 ha watershed on the outskirts of Guelph, Ontario, was established in 1965 as an International Hydrological Decade project for the purpose of studying impacts of urbanization on hydrologic response. A relatively extensive hydrologic database regarding precipitation, streamflow, soil moisture, and groundwater has been assembled for the preurbanization period from 1966 to 1974 and for the period of ongoing development from 1975 to 1982. The study area, located physiographically within the Guelph Drumlin Field, was used for mixed agricultural purposes prior to 1974. During 1975 and 1976, 155 ha of the basin were serviced for development for light industrial and commercial usage, dramatically altering the configuration of the drainage system. The major alteration was the installation of a stormwater conveyance system, consisting of a large-diameter storm sewer (2.5 and 3.0 m) and a network of open drainage ditches outletting through ditch inlet catch basins into a main drainage channel.With the changes in land use in the basin have come changes in both volumetric and time distribution aspects of hydrologic response. Changes in the response include (i) an increase in the mean annual runoff coefficient by a factor of 1.5, (ii) an increase in the average annual maximum instantaneous discharge by a factor of almost 3.0, (iii) a change in the time of the annual peak flow from occurring solely in the spring runoff period to occurring throughout the various seasons, (iv) a change in the seasonal pattern of monthly runoff coefficients, with the greatest change observed in the summer and lesser changes observed in the other seasons, (v) a 3-fold reduction in unit hydrograph lag time, and (vi) a 3.5-fold increase in unit hydrograph peak discharge. Key words: urbanization, hydrology, surface water runoff, streamflow, watersheds.
Improved relationship for drift loads on buildings
Authors: O'rourke Michael , Wood Evelyn
Published: January 2010

In terms of structural failure, drift loads at changes in roof elevation are the most important snow load. In this paper, present building code provisions and recent research results are reviewed. The mechanics of snow drift formation as well as the parameters that influence these drifts are discussed in depth. Finally, a new empirical relationship for peak drift height and drift load is presented. The input parameters for the new empirical relationship are the width, length, and height of the upper level roof, the elevation difference between the upper level roof and snow on the lower level roof, and the ground snow load. Comparisons with case history measurements indicate that the new empirical relationship is a marked improvement over existing relationships. Key words: snow, loads, roof, drift, fluid mechanics, building codes.
Explanatory and forecasting capabilities of trip distribution models
Authors: Volet P. , Hutchinson B. G.
Published: January 2010

Trip distribution models attempt to capture two effects and these are changes in the overall scale of travel between some base year and forecast year as well as fundamental changes in commuting structure. The paper begins with a very brief discussion of observed commuting changes in the Toronto region between 1971 and 1981 using the census journey-to-work data. The abilities of a doubly constrained gravity model to emulate interzonal commuting flows in 1971 and 1981 are examined as well as its ability to forecast 1981 flows. These explanatory and forecasting capabilities are compared with those of a Fratar-type trip distribution model. The trip interchange residuals for both model types are isolated and interpreted in terms of the changes in spatial structure that have occurred in the Toronto region over the analysis period. It is concluded that the forecasts provided by the Fratar model are much superior to those of the aggregate doubly constrained gravity model. Both model types have difficulties in emulating shifts in commuting structure that are due to fundamental changes in living and working patterns by the various socioeconomic groups.
Effect of insulating sheathing on heat and moisture flow
Authors: Timusk J. , Doshi H. B.
Published: January 2010

Wood-frame walls with low and high water vapour permeance insulating sheathings were tested in a climate simulator with respect to moisture and thermal performance. Exfiltration of moist interior air through the walls was simulated by pumping moist air into wall cavities from the warm side of the climate simulator where the walls were tested. It was found that ventilation slots in extruded polystyrene sheathing did not improve the drying ability of the walls. Incomplete filling of wall cavities with glass-fibre batt insulation, the presence of ventilation slots, and temperature difference across the walls had, if at all, a very small effect on thermal performance. The ability of glass-fibre-board insulating sheathing to store water condensed from exfiltrating air was improved by installing the sheathing with the spun-bonded polyolefin membrane facing the cold side. Key words: exterior walls, insulating sheathing, air exfiltration, condensation, thermal resistance, workmanship.
Inelastic lateral buckling of steel beam–columns
Authors: Cuk P. E. , Bradford M. A. , Trahair N. S.
Published: January 2010

A series of investigations of the inelastic lateral buckling behaviour of steel beam–columns is described. These originate from many previous studies of the elastic lateral buckling of beams. It was found that present methods of predicting the effects of moment gradient in elastic beam–columns are unnecessarily conservative, and it was concluded that many practical continuous beam–columns will have significant warping restraints.Fourteen inelastic lateral buckling tests were carried out on 9 continuous steel beam–columns. The results of these tests were compared with predictions made by a new and improved finite element computer method of analyzing inelastic buckling, and very good agreement was found. The analytical method was then used to develop a simple approximation for predicting the inelastic buckling of isolated beam–columns with unequal end moments, and a design method was proposed. Key words: beams, buckling, columns, flexure, residual stresses, steel, structural design, structural engineering, torsion.
Differential movements and stresses in high-rise masonry veneers: Case study
Authors: Fenton G. A. , Suter G. T.
Published: January 2010

This paper deals with a case study of brick masonry veneer distress on a reinforced concrete high-rise structure. The key cause of distress was the absence of a movement joint at the underside of the shelf angle at each floor level. A computer model introduced by the authors in a previous analysis paper is used to investigate the effects of various parameters on differential movements and veneer stresses. The results indicate that the provision of movement joints of at least 3–4 mm/storey would have prevented a buildup of significant veneer stress. In the absence of a movement joint, veneer stresses were found to be high enough to result in distress as observed on the case study structure. The paper concludes with a discussion of repair considerations.
Effect of confinement on the behaviour of high-strength lightweight concrete columns
Authors: Basset R. , Uzumeri S. M.
Published: January 2010

This paper summarizes an experimental investigation into the behaviour of high strength sand – lightweight concrete columns confined with rectangular ties. Fifteen reinforced and three unreinforced specimens were tested under monotonically increasing axial compression. Variables considered in this study were the longitudinal steel distribution and tie configuration, the tie steel spacing, the amount of tie steel, and the amount of longitudinal steel.The results indicated that unconfined high-strength lightweight aggregate concrete is a brittle material. The addition of lateral confining steel significantly improved the behaviour of this material, with a large amount of lateral steel resulting in very ductile behaviour. The tie configuration and resulting distribution of longitudinal steel contributed significantly to the confinement of concrete, with well-distributed steel resulting in improved behaviour. The ratio of specimen to cylinder concrete strength was observed to be 0.98, which is much higher than the commonly assumed value of 0.85.The test results were compared with results from selected theoretical confinement models. Based on the results of this investigation, existing models for concrete confinement give unconservative results for high-strength lightweight aggregate concrete and overestimate the ductility that can be achieved with this material. Key words: columns, confinement, ductility, high-strength concretes, lightweight aggregate concretes, reinforcement, stress–strain relationships, tests, ties, toughness.
Characteristics of large truck–trailer combinations operating on Manitoba's primary highways: 1974–1984
Authors: Clayton A. , Lai M.
Published: January 2010

Weight and dimension regulations governing large truck operations in Manitoba and western Canada generally have been substantially relaxed since 1974. These changes have facilitated the use of larger and heavier truck–trailer combinations on highways throughout Manitoba and on interconnecting highways in adjacent jurisdictions. Effective engineering of these highways and their bridges requires a solid understanding of the physical and use characteristics of the truck–trailer combinations that have been, and are being, adopted by the trucking industry in response to the relaxed regulatory environment.This paper examines certain of these characteristics based on an analysis of hitherto unpublished on-road truck surveys conducted over the years by the Manitoba Department of Highways and Transportation. The following characteristics are examined: (i) changes in the truck fleet mix, (ii) changes in the tare weights of large vehicle combinations, (iii) distributions of gross vehicle weights for particular vehicle combinations, (iv) distributions of weight payloads handled by particular vehicle combinations, and (v) certain dimensional characteristics of import to understanding vehicle loads on highways and bridges. As possible, these characteristics (and changes in them) are related to prevailing weight and dimension regulations (and changes in them). Key words: weight and dimension regulations, truck–trailer combinations, truck weights, axle spacings, on-road truck surveys.
Thermal analysis of engineering structure by the finite strip method
Authors: Mańko Zbigniew
Published: January 2010

In order to calculate internal forces of a structure resulting from heat input, it is necessary to know how thermal conduction in relation to specific material properties and boundary conditions determines the temperature distribution at various points of the structure. The finite strip method (FSM) is very suitable for the analysis of heat and temperature distribution, heating, and thermal conduction in engineering structures. It (FSM) is especially suitable for those structures of rectangular shape and of identical edge conditions.The work presented illustrates several examples for various types of engineering structures utilizing the FSM for the analysis of thermal conduction and heat and temperature distribution, such as, for instance, the welding of several joined elements with linear welds made at a specified speed or as point welds. Types of structures subject to thermal analysis may be bars, shields, square and rectangular plates, steel orthotropic plates, steel and combined girders (steel–concrete), and box girders. The obtained results may be useful in engineering practice for determining actual temperatures and load capacities in individual elements of the construction. Key words: structural engineering, thermal analysis, finite strip method, heating, thermal conduction, temperature, engineering structures.
Resistance to flow in gravel-bed rivers
Authors: Bray Dale I. , Davar Kersi S.
Published: January 2010

An emphasis is placed on the importance of understanding the processes responsible for resistance to flow and on the necessity of critically reviewing the assumptions and limitations associated with the methods that are commonly adopted to evaluate resistance to flow in gravel-bed rivers.A commonly applied technique is first presented for estimating the local effective boundary roughness, ks, by the use of data from a vertical velocity profile. Then methods of estimating bulk measures of resistance to flow in a river reach are outlined. Resistance equations in terms of the friction-factor parameter, [Formula: see text],are classified into three main types: dimensional power equations, nondimensional power equations, and nondimensional semilogarithmic equations. The results of seven independent studies are considered when recommending tentative equations for each of the three defined classes of resistance equations. The bulk flow equations are considered to be applicable for the case where d/D50 is greater than 10, there is no bed-load transport, and the flows are in-bank flows. Finally, a brief summary of the problems of estimating resistance to flow for an ice-covered channel is presented. Key words: resistance, flow, hydraulics, rivers, gravel-bed, velocity, friction factor, equations, Manning, Keulegan, classification.
Shear behavior of large-diameter fabricated steel tubes
Authors: Mok J. , Elwi A. E.
Published: January 2010

In this study, stability failure of large-diameter fabricated steel cylinders subject to transverse shear is numerically investigated. Failure under these conditions may occur as a consequence of shear buckling in regions of low moment and high shear. However, shear buckling, by itself, need not lead to a mechanism. Structural failure should take place as a consequence of the development of a tension field.A number of geometrically perfect and imperfect cylinders (R/T = 250) are analysed under different boundary conditions and levels of geometric imperfections. The results are compared with classical theories and with recent experimental results. It is concluded that initial buckling takes place in an inclined shear mode. The level of initial buckling is sensitive to the geometric imperfections. Subsequently a definite tension field develops that may lead to the formation of a meehanism. However, comparisons with experimental results show that fabrication residual stresses, which were not taken into consideration, may affect the nature of the load response. Key words: buckling, cylinder, imperfection, shells, stability, tension field, transverse shear.
Behavioral load testing of the Disraeli facility
Authors: McCulloch W. J. , Militano C. , Rizkalla S.
Published: January 2010

The Disraeli facility, which was completed in 1960, consists of several overpasses utilizing rolled steel beam construction and a riveted steel plate girder bridge crossing the Red River in Winnipeg, Manitoba. The total length of the facility is approximately 707 m (2320 ft). In 1984, the City of Winnipeg commissioned Reid Crowther and Partners Limited to perform a load test on the facility to ascertain the possibility of increasing the maximum gross vehicle weight limit. The tests were performed on three consecutive Sundays, from September 23 to October 7, 1984.Three spans were tested. One normal and one skewed span were selected for the overpasses to study possible differences in their behavior along the exterior span of a three-span continuous riveted plate girder bridge over the Red River. The test was designed to determine the structural response of the bridges at different load levels, to determine the load distribution characteristics, and to investigate dynamic impact values for the test vehicles.This paper describes the instrumentation layout, data acquisition system, test vehicles, and testing procedures. Test results and comparisons with the predicted values utilizing conventional analysis are included.
Stormwater pollution modelling: minor sources of pollutants in urban sewer networks
Authors: Shivalingaiah Boregowda , James William
Published: January 2010

In addition to the well-known, major pollution processes of dry weather buildup and wet weather washoff and routing, some less obvious minor processes contribute background pollutants to urban stormwater. Since related pollutant loads during storm events are not significant, the processes are termed "minor." These processes, which appear to be seasonally persistent, include aerosol and gaseous scavenging from the atmosphere, leaf canopy washoff, dry weather base flow, and local deposition/erosion due to obstructions.Equations are presented for each process. Algorithms for these equations were incorporated in version 3 of the U.S. Environmental Protection Agency stormwater management model (SWMM3) and tested collectively. The modified version is known as CHGQUAL. The effect of variable time steps in the computational scheme is discussed.CHGQUAL evidently contains more process-oriented algorithms and may predict surface water pollution management options better than SWMM3. Until more definite data becomes available, however, CHGQUAL should of course be used with caution. Key words: precipitation scavenging, canopy washoff, base flow, water pollution, air pollution, stormwater management models, urban runoff.
Strength evaluation of an existing concrete bridge based on core and non-destructive test data
Authors: Scanlon Andrew , Mikhailovsky Leonid
Published: January 2010

The use of concrete cores and nondestructive testing for strength evaluation of existing structures is illustrated through an evaluation of an existing concrete bridge. The results confirm that rebound hammer number should not be used alone as an indicator of in situ compressive strength. Reasonably good correlation is demonstrated between pulse velocity and compressive strength, with a slight improvement when pulse velocity and rebound number are combined.A probabilistic approach to structural evaluation of existing structures is proposed in which the variability of in situ concrete compression strength and uncertainty associated with indirect nondestructive testing are incorporated. An example of shear strength evaluation is given, which indicates a range of increase in shear strength compared with initial design parameters of 17–37% depending on the amount and type of data available.
Steel–wood composite bridges and their static load response
Authors: Bakht Baidar , Tharmabala Tharmalingham
Published: January 2010

The proposed steel–wood composite bridges incorporate longitudinal steel girders which are composite with wood deckings consisting of longitudinal laminates. The laminated decking is usually transversely prestressed. By orienting the laminates longitudinally, advantage can be taken in longitudinal bending of the dominant modulus of elasticity of wood. The paper shows that the load-carrying capacity of an existing slab-on-girder bridge with steel girders and deteriorated noncomposite concrete deck slab can be considerably enhanced by using the proposed system. The paper presents results of static load tests on two types of shear connector, some composite beams, and half-scale model of a bridge. Test data confirm the effectiveness of the composite system. Key words: bridges, composite bridges, steel–wood composite bridges, laminated wood decks, shear connectors, composites.
Factors affecting the behaviour and modelling of toothed metal-plate joints
Authors: Lau Peter W. C.
Published: January 2010

An efficient approach to determine the behaviour of toothed metal-plate joints is to use analytical techniques to model the behaviour on the basis of known properties of plate and wood, and loading conditions, backed by an actual testing of the joints for verification or calibration of the models. Existing computer-based techniques such as the Structural analysis of trusses (SAT) and Purdue plane stress analyzer II (PPSA II) were developed for modelling wood trusses. The applicability and usefulness of these techniques can be expanded if better joint models can be incorporated into SAT, or if PPSA II can be advanced to describe the behaviour of joints. The present experiment included obtaining load–deformation data on specimens of two designs — one for the shear properties of plate and the other resembling the heel joint of a truss. These data were compared with predictions given by SAT. In addition, data from the heel joint specimens were used to calibrate the property requirements of fictitious members used in PPSA II to model semirigid joint behaviour. Predictions of joint stiffness by SAT were reasonably accurate, but the ultimate load was overestimated when the joint failed in plate buckling. The heel joint test method shows potential as a proper and efficient test method for assessing joint behaviour. However, as is normal with any joint testing, a significant frictional force can develop between joint members and contribute to the ultimate strength and stiffness of the joint. This frictional force should be accounted for in modelling. Key words: design, interface friction, modelling, shear strength, stiffness, structural analysis, truss plate, wood truss.
Modifications to the design procedure for grit chambers
Authors: Agrawal Sunil K. , Bewtra Jatinder K.
Published: January 2010

A modified approach to the design of grit chambers has been suggested in this paper. This approach is based on the concept of critical shear stress at the bed rather than mean velocity as used by T. R. Camp. It is recognized that the relationship between critical bed shear stress and mean velocity in a channel is not constant, as assumed by Camp, but varies according to the flow conditions. Critical bed shear stress values, obtained in the laboratory for different particle characteristics, are given in this paper. The proposed method should provide a more rational and a better design procedure for grit chambers. Key words: grit chambers, scouring, bed shear stress, initiation of motion.
Biological phosphorus removal at an experimental full-scale plant in France
Authors: Florentz M. , Hascoet M. C. , Bourdon F.
Published: January 2010

In France, all phosphorus removal treatment has been based on precipitation by means of chemical reagents. With a view to reducing costs, a series of laboratory experiments was initiated and subsequently followed up by full-scale studies in early 1984 at the Saint-Mars-la-Jaille treatment plant. This is the first biological P-removal plant to be put on line in France.The plant operates at low loading levels with extended aeration. Nitrification–denitrification is achieved in controlled aerobic and nonaerobic zones through a multi-mini-step process in a plug–flow reactor. Complete nitrate removal results in a release of phosphorus during the anaerobic phase and, hence in a high level of phosphorus accumulation in the aerobic sludge.Phosphorus removal was optimized by replacing the thickener with a new flotation thickener to minimize P-release in the anaerobic sludge blanket. The phosphorus removal levels obtained varied from 35% at the outset of the study to 89% upon stabilization. This paper outlines the basic technical alterations made to ensure efficient phosphorus removal with this type of sewage plant as well as the analytical procedures used, and identifies the polyphosphates accumulated in activated sludge, on the basis of 31-phosphorus nuclear magnetic resonance (31P nmr).Results concerning phosphorus removal at low temperatures are also provided. Key words: activated sludge, wastewater treatment, biological phosphate removal, anaerobic conditions, restricted oxygen, nuclear magnetic resonance, flotation, temperature.
Performance of small progressive cavity pumps with solar power
Authors: Ward Peter R. B. , Dunford William G. , Pulfrey David L.
Published: January 2010

A small progressive cavity pump, rated at about 900 W, has been assembled and tested as part of a photovoltaic-cell-powered water pumping system. Torque-speed relationships for the progressive cavity pump, not readily available in published engineering journals, were measured and are presented. The pump was extremely well suited to lifting groundwater for small (domestic) supplies with solar power because it was capable of producing the full design head over a very wide range of speeds. In addition, the progressive cavity pump was robust, and unlike most other positive displacement pumps, would tolerate small concentrations of silt and sand in the water without damage. Very many of these pumps are already in use in parts of Africa and other developing areas, and excellent prospects exist for operating progressive cavity pumps with solar-energy-powered drives. Key words: pump, solar power, groundwater, water, water supply, solar, well, hydrology, hydraulic.
Composite cold-formed steel–concrete columns
Authors: Abdel-Sayed George , Chung Kwok-Cheung
Published: January 2010

A new system of composite columns is developed using lipped cold-formed steel channels with embossments and cast-in-place concrete. The combined action of the embossments and the channel's lips leads to very good bond between the steel and the concrete. It has been found that by replacing the standard longitudinal reinforcing bars by cold-formed steel sections of equal area, the structural performance of the columns remains almost unchanged, while considerable savings are achieved in time and material of construction. The present paper outlines the main characteristics of the proposed columns and provides an approach for their analysis and design, which is verified experimentally. Key words: columns, composite structures, concrete (reinforced), construction, cold-formed steel.
Drogue-cluster and dye-dispersion measurements
Authors: Palmer Merv D. , Jarvis Rob , Thompson Larry
Published: January 2010

Near the water surface, dispersion and transport were extensively measured in the coastal regions of Lake Ontario using dye patches and clusters of water sail and surface drogues. The measurements were carried out for 6–8 h. Each method produced different measurements of dispersion magnitudes with the largest dilution occurring for the dye, followed by sail drogue clusters (40% of the dye's value) and then surface drogue clusters (25% of the dye's value). Both the sail and surface drogues measured the two-dimensional dispersion. The mean surface dispersion was about 50% less than the dispersion 1.5 m below the water surface. The dilution characteristics decreased as the water surface was approached. The sail dispersion was about half of the dye-dispersion data. It was not known how much of the difference was attributable to the dye being three-dimensional and affected by dispersion in the vertical direction; consequently, as time progressed, the dye patch was measuring dispersion at greater depth than the water sail drogues, which were set for a depth 1.5 m below the water surface. The statistical increase of the variance with time was computed for each method of measuring dispersion, and the results were compared. A method for predicting dilution envelopes for a location using the path lines of the drogue-cluster centroids or center of mass of the dye patch was developed for both a batch release and a continuous discharge. These dilution envelopes are based entirely on Lagrangian data for both the velocity and dispersion estimates. Key words: lake, dispersion, drogue clusters, dye, surface streaking.
The influence of strain history and strain gradient on confined concrete
Authors: Ersoy U. , Tankut A. T. , Uzumeri M.
Published: January 2010

This paper outlines the results of tests performed to study the effect of strain gradient, strain history, and initial precracking on the efficiency of confinement in reinforced-concrete columns. To this end, five reinforced-concrete specimens with closely spaced ties have been tested under combined flexure and axial load.Two of the specimens were used as control specimens, subjected only to a strain gradient. The remaining three specimens were precracked using different loading schemes and then tested under a combination of flexure and axial load. Two of these specimens were tested with repeated loading.The test results revealed that precracking lowered both the flexural rigidity and the ultimate capacity of the specimens. No significant differences were observed due to the type of loading used to initially crack the specimens. Repetition of loading did not seem to affect the ultimate capacity of the specimens.Comparison of the test results with four analytical models for confined concrete showed that the models that predicted the behaviour of the control specimens accurately, overestimated the capacities of the precracked specimens. The Thompson and Park concrete model accurately predicted the behaviour of the specimens tested with repeated loading. Key words: reinforced concrete, confined concrete, confinement, columns, cyclic loading, precracked column, experimental.
Damped moment-resistant braced frames: a comparative study
Authors: Baktash Parvaneh , Marsh Cedric
Published: January 2010

This paper reports a study on the comparisons between the behaviours of braced steel building frames with friction joints and with eccentric bracing, under seismic forces. Nonlinear time-history dynamic analysis is used. Friction damping is shown to be of particular merit. Key words: bracing, damping, ductility, dynamics, earthquakes, eccentric; energy dissipation, friction, hysteresis loops, response, steel frames, time history.