bluuebunny/crossref_metadata_2025 huggingface dataset:
Bituminous surface treatment and its effectiveness as a municipal road surface—Faro, Yukon
Authors: Cotterill Robert
Published: January 2010

The use of bituminous surface treatment (BST) as a road surface is a technique commonly accepted and understood by most provincial and territorial highways departments, but for the average engineer or municipality, it may be nothing more than the squirting of some oil on a road surface and covering this oil with some gravel.The topic of BST construction brings with it many different approaches, applications, and techniques. In the Yukon, Alaska, and western Canada, the two basic techniques used are: rapid setting emulsions and chip aggregates or high float emulsions and well-graded aggregates.Before the right approach is arrived at, an analysis of the expected traffic volumes, the condition of the sub-base, the quality and quantity of aggregate available, the types of emulsions available, and the cost of installing either of the techniques should be undertaken.In 1981, the town of Faro hired a local Whitehorse contractor to single surface treat 4.5 km of local roads, the final result being a combination of pot holes, ravelling, and streaking. A detailed investigation was undertaken to determine why the problems were experienced and to ascertain whether BST should be used on municipal streets in the future.The research indicated that the general design principles were correct but that an overabundance of gravel being specified, coupled with numerous errors in construction, produced an inferior product.A second treatment of approximately 1.5 km of road was undertaken in 1982 by a more experienced applicator, namely, the Yukon Government Highways forces, and many of the problems experienced in 1981 were overcome.The purpose of this paper is to present both the problems experienced in Faro and what approaches, applications, and techniques should be followed to minimize the possibility of these problems occurring in the future. Key words: aggregate, asphalt emulsion, tack coat, sub-base, bituminous, soil cement, streaking, pneumatic.
Estimation of the mass of large snow avalanches
Authors: Schaerer Peter A. , Fitzharris B. Blair
Published: January 2010

The mass of avalanches was investigated using two series of observations made at Rogers Pass in Western Canada. Large avalanches occur once in 3 – 25 years at each avalanche path, and their mass greatly exceeds that of annual maximum avalanches. Standard extreme-value frequency distributions cannot be applied. An empirical predictive equation for the mass of large avalanches is presented that takes into account the 30-year maximum water equivalent of the snow in the avalanche path, surface area of the catchment, and incline of the starting zone. Observed avalanches with an apparent return interval of 100 years or greater had masses close to the predicted values. Key words: snow avalanches, mass, frequency, design.
Air-entrained grouts suitable for post-tensioning
Authors: Loov R. E. , Hon S. P. , Ward M. A.
Published: January 2010

Grouts in post-tensioning ducts can cause cracking of the structural member if the grout freezes at an early age. This laboratory program examines a range of cement–water grouts with differing w/c ratios, air contents, and ages. A new empirical test method employing a test bottle was introduced to study the performance of grouts during early freezing.It was determined using the bottle method and other experimental and analytical procedures that excessive grout dilation during early freezing could be avoided if the entrained air content of the grout exceeded[Formula: see text]where w/c is the original water-to-cement ratio of the grout and M is the fraction of the cement that has hydrated before the grout freezes.
Rain absorption and runoff on porous building surfaces
Authors: Hall Christopher , Kalimeris A. N.
Published: January 2010

The absorption of rain by porous building surfaces is discussed in terms of unsaturated flow theory. Simple formulae not previously published are presented to calculate the time to reach surface saturation and the absorption rate. These formulae are compared with the model of E1-Shimi et al.
Rainfall–elevation relationships in the Wilson Creek Experimental Watershed
Authors: Goulter I. C.
Published: January 2010

The rainfall patterns in the Wilson Creek Experimental Watershed in Riding Mountain National Park are analysed. Since this watershed lies on the Manitoba Escarpment there is a relatively sudden change in elevation across the watershed. The average annual rainfall is plotted against station elevation and against distance of the rainfall stations from the National Park boundary. Two distinct trends were observed. The average annual rainfall increases significantly from the bottom to the top of the escarpment. The average annual rainfall also levels off very quickly as the relatively flat plateau at the top of the escarpment is reached. No carry-over effects from terrain-induced upflow enhancement were observed. Key words: Manitoba Escarpment, rainfall variation, topography, upflow enhancement, Wilson Creek.
Sensitivity analysis with dynamic programming
Authors: Russell S. O. Denis
Published: January 2010

A way is presented for making a sensitivity analysis to find by how much the total cost increases as one moves away from the optimal solution obtained by dynamic programming. It is illustrated using a simple storm drain optimization problem. Key words: dynamic programming, sensitivity analysis, optimization.
Comments on the health and safety in construction aspects of the Proceedings of the IABSE Workshop, Tokyo, 1982
Authors: Litster R.
Published: January 2010

Two of the major factors in reducing industrial injuries and diseases include motivation and monitoring of effectiveness. A comparison of these factors in published proceedings of an IABSE Workshop in Japan, particularly as they relate to Japan vs. Ontario, is presented in this article.Carefully planned involvement of those commissioning construction can reduce the enormous $1 billion actuarial deficit for compensation in the construction industry of Ontario.
A study of end plate connections for steel beams
Authors: Kennedy D. J. Laurie , Hafez Mona A.
Published: January 2010

End plates welded transversely to the web of the beam and then bolted to the supporting member should provide effective, simple connections to transmit shear. However, under loading, the end of the beam rotates and moments are developed in the connection. It is essential that the end plate connection be sufficiently flexible so that the factored moment can be attained in the beam without the development of excessive moments in the connection itself. Based on the behaviour of T-sections, where the flange of the T simulates the end plate and the stem simulates the web of the beam, both when the stem is loaded in tension and in compression, analytical procedures have been developed to predict the moment–rotation behaviour of end plate connections. Good agreement has been obtained between the predicted nonlinear moment–rotation curves and the experimental curves for eight connections covering a practical range of end plate thicknesses, gage distances between bolt holes, and connection depths. With the proposed analytical expressions the designer is able to predict the behaviour of a connection to ensure it has sufficient strength and flexibility. Key words: beams, connections, deformation, design, end plates, plates, rotation, shear strength, steel, stresses, tests.
Design for seismic torsional forces
Authors: Humar J. L.
Published: January 2010

An analytical study of the responses of a single storey and a multistorey building model to a combined translational and rotational ground motion is presented. The models, which are assumed to be elastic, are eccentric about one plan direction but are symmetric about the perpendicular direction. The ground excitations are represented by idealized spectra.A critical evaluation is made of the torsion provisions of the National Building Code of Canada. It is shown that the code provisions, while not necessarily nonconservative, are somewhat difficult to apply for multistorey buildings. An alternative provision for design eccentricity is proposed. The forces obtained by the use of the proposed method are compared with the analytical results of single storey and multistorey building models and are shown to provide an adequate design basis.
Microorganism survival in an ice-covered river
Authors: Putz G. , Smith D. W. , Gerard R.
Published: January 2010

The study reported herein involved investigations of microorganism survival under ice conditions downstream of the Fort Smith, N.W.T., wastewater disposal site. The Fort Smith wastewater treatment and disposal system consists of two primary lagoon cells and a facultative cell, followed by a continuous discharge to the Slave River through a submerged near-shore outfall.Microorganism sampling and analyses for total and fecal coliforms were conducted for each sampling station. After accounting for the physical dilution the limited data showed a barely discernible microorganism die-off within the study reach for the ice-covered conditions. Key words: mixing, coliform bacteria, dilution, sewage disposal, outfall sewers, fluorescent dye, indicator species, stream pollution.
Thermal performance of sheet steel walls exposed to fire
Authors: Bardell K. H.
Published: January 2010

Unexposed wall surface temperatures are used to determine spatial fire separation requirements for buildings.A series of 10 small-scale fire tests of insulated sheet steel walls was conducted to study the influence of wall fastening details, surface ventilation, and insulation thickness on these temperatures.Test results showed that thermal performance is affected by all three parameters, in particular insulation thickness. A one-dimensional heat transfer analysis and an empirical formula predicted test results accurately.La température de surface des murs non exposés est utilisée pour déterminer les exigences de résistance au feu requises dans les bâtiments.
Field investigation of out-of-plane deviations for steel box girder bridges
Authors: Korol R. M. , Thimmhardy E. G. , Cheung M. S.
Published: January 2010

The degree of geometrical imperfections existing in the plate panels of six in situ steel box girder bridges located throughout Canada is reported. The purpose of a continuing investigation is to establish the extent to which strength and performance of Canadian box girders in multispan bridges are sensitive to imperfections. The 95% fractiles obtained from the imperfection measurements of webs and bottom flanges are shown to vary considerably from one bridge to another but, in general, tend to decrease with increasing plate thickness. Key words: bridges (box girder), field measurements, geometric imperfections, plate panels, structural steel.
Analysis of concrete structures subjected to sustained temperature gradients
Authors: Sivakumaran K. S. , Dilger Walter H.
Published: January 2010

A simple method using aging coefficients and “creep-transformed” section properties is presented for computing time-dependent effects in uncracked concrete members subjected to sustained loads and sustained temperature gradients. The creep coefficients at elevated temperatures are determined using a normalizing function for temperature. The method is applied to prestressed continuous beams and the results are compared with experimental data. Key words: analysis, concrete (prestressed). concrete (reinforced), creep, loads (forces), shrinkage, structural engineering, temperature.
Nonlinear behaviour and failure analysis of multicell reinforced concrete box girder bridges
Authors: Seible Frieder , Scordelis Alex C.
Published: January 2010

A numerical method of analysis is developed to trace the nonlinear response of multicell reinforced concrete (RC) box girder bridges under stepwise increasing static loads. The nonlinearities considered are material nonlinearities inherent in reinforced concrete structural members, such as cracking of the concrete and yielding of the reinforcement due to flexure, shear, and torsion. The analytical model, based on a three-dimensional grillage, is developed for multicellular structures of arbitrary plan geometry and constant height. The analytical method can trace the complex nonlinear behaviour of the bridge beyond the working stress range up to ultimate failure and collapse of the structure. Collapse mechanisms and failure loads can both be determined. The proposed analytical scheme, which is based on a mixed model formulation, is demonstrated and tested on two numerical examples. The results are compared with experimental results obtained from large-scale tests on RC box girder bridge models and indicate excellent agreement. The behaviour of these bridge models under increasing overloads is discussed. Key words: box girder bridges, bridge design, multicell structures, reinforced concrete, analytical model, nonlinear analysis, mixed model, ultimate strength, failure modes.
Thermal loading of concrete bridges
Authors: Hirst Malcolm J. S.
Published: January 2010

This paper presents the results of a parametric study into the thermal loading of concrete bridges by solar radiation. All results were obtained using a computer model calibrated from field measurements. The model computes the loading parameters from the bridge characteristics and the standard daily records of the weather bureau. The design method given uses an effective thickness concept to find the effects of a wearing course on the temperature profile of the underlying bridge. Thermal loading depends on climate and is extremely variable. Histograms are presented, which show the frequency distributions of the loading parameters for sample bridges at three Australian sites covering a range of climatic regimes from tropical to temperate. Key words: bridges, concrete, loads, temperature, solar radiation, structural engineering, design chart.
Variation of ground snow loads with elevation in Southern British Columbia
Authors: Claus B. R. , Russell S. O. , Schaerer P.
Published: January 2010

Measurements conducted at 20 locations in Southern British Columbia were used to investigate the relationship between design ground snow load and elevation. It was found that the increase in water equivalent with elevation (i.e., the slope of the graph of water equivalent plotted against elevation) could be defined for regions having similar climatic conditions. For a given location, the design ground snow load can therefore be estimated by extrapolating from the water equivalent value at one elevation, where it has been measured, to the elevation at the location in question.Plots of the absolute values of water equivalents against elevation for regions of similar climatic conditions gave less satisfactory relationships but they could still be used to estimate approximate values of the design ground snow loads for any particular site.
Full-scale testing of a prestressed concrete segmental bridge
Authors: McClure Richard M. , West Harry H.
Published: January 2010

An experimental prestressed concrete segmental bridge was constructed and tested at The Pennsylvania State University. The bridge was designed as dual single-span curved girders with a length of 36.88 m (121 ft). Each girder was composed of 17 segments. The bridge was constructed in 1977, field tested at service-load levels during the summer of 1978, and tested for overloads during the summer of 1981 when one girder was tested to failure.The experimentally determined service load responses were found to be about 15% less than the corresponding finite element values. For the cases where a simplified design method was employed, the response was correspondingly greater than the finite element method. Thus, the actual structure was considerably stiffer than that predicted by theory. These results were based upon comparisons which were made for several longitudinal and transverse positions of the test vehicle.The results of an incremental loading to failure were compared with a finite element study that used Kostovos and Newman's material model for concrete. This technique models the cracking patterns and material nonlinearities of the concrete, and the results compared reasonably well in the elastic and postcracking range up to failure. A simplified classical approach also gave reasonably good results. Key words: bridges, concrete, curved beam, failure, field tests, mathematical model, nonlinear behavior, prestressed concrete.
A conceptual model of river ice breakup
Authors: Beltaos S.
Published: January 2010

A conceptual model of ice breakup is formulated and used to analyze and compare data from four river gauge sites. Emphasis is on the development of generalized short-term forecasting methods, which to date have been site specific. The features to be forecast are the onset and flooding potential of breakup. These are related to the water surface width available for passage of the large sheets of ice that form by transverse cracking of the ice cover. Thus it is possible to study the effects of parameters such as ice cover dimensions and channel geometry. Owing to a lack of pertinent data, other parameters such as ice mechanical properties and flow characteristics are only considered indirectly. The mechanism of transverse cracking is examined in the light of recent field observations. Bending on planes parallel to the water surface, caused by stream curvature, could account for the observed crack spacing but more data are needed for positive conclusions. The present model does not apply in cases of “overmature” breakup, proximity of stage controls, and river planforms different from the single meandering channel type. Key words: breakup, cracks, field data, forecasting, gauge records, ice, ice clearing, ice sheets, model, onset, river ice, rivers.
MIDUSS—A design program for storm water sewerage
Authors: Smith Alan A. , Falcone Joseph P.
Published: January 2010

Many programs that are used for storm water management are intended primarily for analysis or simulation. The MIDUSS program facilitates the design of conveyance or detention storage elements in a tree network. The program is command driven and allows the design to proceed in a traditional manner by allowing the user to define individual subcatchments to generate the overland flow. The resulting hydrographs may be manipulated and used to design pipe and pond elements of a drainage network. The user can experiment with alternative trial designs.As the design proceeds, a file records the data input and design decisions made by the user. This file may be used in subsequent design sessions during which the user may switch from manual (i.e., keyboard) to automatic (i.e., file) input. This allows continuation of a previous design session, testing of a prior design with a different storm, or redesign of specific elements of the system.In either mode, the user can monitor progress at each step and take corrective action in the event of bad data or incorrect design decisions. Key words: computer, design, storm water, sewer, detention, pond.
Traffic loads on medium and long span bridges
Authors: Harman D. J. , Davenport A. G. , Wong W. S. S.
Published: January 2010

A procedure is described for calculating two statistics, the mean and the coefficient of variation, for largest live load effects in a bridge structure caused by highway traffic during a reference period. These statistics are pertinent in the selection of highway live loads and calibration of a statistically based design code. The reference period depends on the limit state being calibrated.Using weights and dimensions of trucks from a 1982 survey in Ontario, congested traffic moving through one bridge length is repeatedly simulated for various “truck densities.” Herein truck density is the number of trucks on a length of highway divided by the maximum number that could occupy the length. When simulating traffic of one density crossing one influence line, the largest structural effect per traffic move has a frequency distribution that, with reasonable accuracy, is idealized as Gaussian.Observed multiple truck presence is modelled by a modified Poisson distribution that has three parameters. For one set of these traffic parameters, mean largest structural effects are shown to vary in a consistent manner with truck density, truck volume, and one parameter characterizing the tributary area of the effect. Based on these observations, more concise procedures for simulation and calculation are recommended. Key words: statistics, probability, truck survey, bridge loads, structural effects, bridge design, code calibration.
Fatigue investigation of a railway truss bridge
Authors: Szeliski Z. L. , Elkholy I. A.
Published: January 2010

The advent of unit trains and high gross tonnage has made it necessary to evaluate the effect of repetitive loading on bridges. A description of a fatigue investigation of a 35.7 m (117 ft) railway through truss span is presented. The study consisted of (1) field measurement; (2) theoretical model analysis; (3) traffic analysis; (4) estimate of fatigue damage; (5) evaluation of fatigue detail category; (6) estimate of remaining life; and (7) action required. The effect of car sequence in trains, sample size, flat wheels, and impact on level of stresses is examined. As a result of the study, the trusses were retrofitted by removing rivets, reaming holes, and placing high-strength bolts.
The Pretoria Avenue Bridge—old and new
Authors: Marett D. C. , Hanlan C. E.
Published: January 2010

This paper describes a historic civil engineering bridge site on the Rideau Canal. The history of the site is traced from 1882, when the first bridge was built, to the time of the existing modern structure. Most of the bridges were of the movable type, being either swing or vertical lift structures. The present bridge, which was built in 1980–1981, was designed taking into consideration many of the historic features of past bridges especially the latter bridge, which was built in 1915–1917. Various technical features of the new bridge enhance one's perspective of modem design methods when they are compared with past state-of-the-art methods. The resulting bridge is a functional structure that maintains the heritage of the historic bridges and at the same time blends with the environment.
Cross-sectional properties of cold-formed angles
Authors: Madugula Murty K. S. , Ray Sujit K.
Published: January 2010

Cross-sectional properties of both equal and unequal leg cold-formed angle sections are presented. Besides cross-sectional area, location of centroid, moments of inertia, and torsional constant, the properties listed include the location of shear centre and the magnitude of warping constant. These two latter properties are required for determining failure loads of angles subjected to torsional–flexural buckling. Also listed are two important parameters, β1, and β2, that are required for the calculation of theoretical buckling loads of eccentrically loaded columns. Key words: buckling, cold-formed angles, columns, cross-sectional properties, shear centre, stability, torsional–flexural buckling, warping constant.
Axially compressed members
Authors: Springfield J.
Published: January 2010

This discussion centres on the text Axially compressed structures, stability and strength, edited by R. Narayanan. The writer not only critically reviews the text but expresses his own opinions on the merits and shortcomings of the various authors' chapters. The response to axial compression of members of diverse cross section is cross section shape dependent. Included are the fundamentals of steel column design applied to hot-formed and welded open shapes, considerations of safety from both the European and American viewpoints, and detailed considerations of large box and circular fabricated tubes typical of offshore structures, concrete-encased columns, cold-formed tubes, angles, laced and battened columns and masts, and members with intermittent elastic support (through truss bridge chords).
The Merivale Rail Bridge, Brisbane, Australia
Authors: Snelling J.
Published: January 2010

The Merivale Rail Bridge crosses the Brisbane River and has as its main span a 132 m tied steel arch. The cable pattern is unusual and was derived to maximize the stiffness of the span under railway loading. The river foundations are large diameter piles formed from precast concrete "boats," which became the lower parts of the piers. This arrangement avoided underwater work and provided a robustness commensurate with shipping movements in the river. Approach spans are cast in situ prestressed concrete continuous viaducts except where clearance restrictions to existing roadways necessitated cast in situ prestressed concrete through bridges. Investigation, design, fabrication, and construction are described. Key words: railroad bridges, tied arch, steel construction, bridge foundations, prestressed concrete cables.
Fatigue strength of a groove weld on steel backing
Authors: Baker K. A. , Kulak G. L.
Published: January 2010

Groove welding made from one side is a common fabrication technique for joints in steel structures. If a steel backing bar is used, current (1983) North American specifications require that it be removed after welding and the weld ground flush if the detail is to be located transversely to the direction of stress and fatigue loaded. This is an expensive, and in some cases impractical, procedure. In the investigation reported herein, data concerning the fatigue strength of a groove weld with steel backing bar detail have been obtained experimentally. The backing bar was attached with intermittent fillet welds. A finite element analysis has been used to assist in interpretation of the test results.The analysis showed that high local stresses are present at the toe of the fillet weld. However, high stresses also exist at the flush-ground face of the groove weld, and the test results indicated that all fatigue cracks started at this side of the detail. When this detail is present in a structure and subjected to a fatigue loading, category C of the AASHTO or CSA specifications will provide a suitable basis for design. Key words: failure, fatigue, steel, welding.
Design of the Murray and Wolverine River rail bridges
Authors: Taylor G. W.
Published: January 2010

This paper describes the design of the Murray and Wolverine River rail bridges, two of the largest river crossings on British Columbia's Tumbler Ridge branch line. These unique railway bridges feature a single-cell, continuous steel box girder superstructure supported by pairs of steel delta legs. The top flange of the box girder is an orthotropic deck plate that is a part of the ballast containment trough. Stability of the delta legs is provided by posttensioning of their bases to the concrete substructure. Key words: rail bridge, steel box girder, steel delta legs, orthotropic deck, posttensioning.
Charts for water hammer in low head pump discharge lines resulting from water column separation and check valve closure
Authors: Ruus Eugen , Karney Bryan , El-Fitiany Farouk A.
Published: January 2010

Maximum pressure head rises resulting from water column separation and check valve closure are calculated and plotted for a simple low head pump discharge line with one well-defined high point. Basic parameters such as pipeline constant, pipe wall friction, complete pump characteristics, pump inertia constant, and the relative location of the high point are accounted for in the analyses. The results of this paper can be used to determine (a) when water column separation is expected, (b) how to avoid water column separation, and (c) the necessary wall thickness in cases where no protection against water column separation is provided. Computer studies indicate that both the vertical and horizontal location of the high point as well as the pipe friction, the pipeline constant, and the pump inertia have a major effect on pressure head rises. Water column separation does not always constitute a danger to the pipeline. Key words: waterhammer, water column separation, check valve closure, pressure rise, pump discharge line, chart.
Calibration of the Ontario Bridge Design Code 1983 edition
Authors: Grouni Hid N. , Nowak Andrzej S.
Published: January 2010

The paper summarizes the calibration procedure used to calculate load and resistance factors for the Ontario Bridge Design Code 1983 edition. The limit states considered include serviceability and ultimate limit states during service and in construction. The acceptance criterion is closeness to a predetermined target safety level. Safety is measured in terms of a reliability index. The results of calibration are discussed for composite steel–concrete girders, pretensioned concrete girders, post-tensioned concrete decks, and timber decks. The analysis of construction design criteria is demonstrated on segmental bridges. Key words: code calibration, bridges, reliability index, load and resistance factors, limit states.
Field observations of river bed scour on the Peace River near Fort Vermilion, Alberta
Authors: Harrington R. Alex , McLean D. G.
Published: January 2010

The results of field measurements of general and local scour on the Peace River at Fort Vermilion, Alberta are presented. The Peace River, the largest sand bed river in Alberta, has been regulated by the W. A. C. Bennett Dam since 1968, resulting in a general reduction in spring and summer discharges. Between 1971 and 1974 a 532 m twin box girder bridge structure, supported on steel H piles, was constructed at Fort Vermilion. A number of channel surveys have been carried out at the site at various discharges, providing considerable data with which to evaluate scour formulae used in practice. Comparison of measured results with predicted values of general scour indicates that most equations provide results in general agreement with the observed data, even though some of the regime equations may not be appropriate to sites with significant contractions. Computed local pier scour was generally greater than that measured at the site, although this is partly because of the nature of the pier footing configuration, which tended to arrest local scour. Key words: hydraulics, regime, rivers, sediment, scour.
Flow resistance of ice-covered streams
Authors: Chee S. P. , Haggag M. R. I.
Published: January 2010

This paper deals with the underlying theory of the hydraulics of channel flow with a buoyant boundary as an ice cover. It commences by developing the velocity distribution in two-dimensional covered channel flow using the Reynolds form of the Navier–Stokes equation in conjunction with the Prandtl – Von Karman mixing length theory. Central to the theory is the division of the channel into two subsections. From the developed velocity profile, the functional relationship for the division surface is obtained. Finally, the composite roughness of the channel is derived.Experimental verification of the developed theory was conducted in laboratory flumes. Seven cross-sectional shapes were utilized. Ice covers were simulated with polyethylene plastic pellets as well as floating plywood boards with roughness elements attached to the underside. Velocity profile and composite roughness measurements made in these flumes were in good agreement with the theoretical equations. The composite roughness relationship derived from the theory is very comprehensive, as it takes into account not only the varying rugosities of the channel and its floating boundary but also the shape of the cross section. Key words: composite roughness, ice cover, flow resistance, velocity profile, buoyant boundary, covered channel.
Dynamic loading and testing of bridges in Ontario
Authors: Billing J. R.
Published: January 2010

The Ontario Highway Bridge Design Code (OHBDC) contains provisions on dynamic load and vibration that are substantially different from other codes. Dynamic testing of 27 bridges of various configurations, of steel, timber, and concrete construction, and with spans from 5 to 122 m was therefore undertaken to obtain comprehensive data to support OHBDC provisions. Standardized instrumentation, data acquisition, and test and data processing procedures were used for all bridge tests. Data was gathered from passing trucks, and scheduled runs by test vehicles of various weights. Accelerometer responses were used to determine bridge vibration modes, and dynamic amplifications were obtained from displacement or strain measurements. The form of the provisions adopted for dynamic load and vibration was confirmed by the test results, subject to minor adjustment of values. Observations on the distribution of dynamic load, and its relationship to span length and vehicle weight, may provide a basis for future refinement of the dynamic load provisions. If the stiffness of curbs and barrier walls is not included in deflection calculations, bridges designed by deflection could be penalized. Key words: bridges, vibration, bridge testing, bridge design codes.
The rational method revisited
Authors: Smith Alan A. , Lee Ken-Beck
Published: January 2010

Despite the increasing availability of more-sophisticated methods for simulating rainfall–runoff events, the 'rational method' continues to be used as a design tool in many municipal engineering offices. This paper examines the basic assumptions of the method and shows how hydrographs from impervious areas can be accurately simulated by a simple convolution process using the rectangular response function implied in the rational method. The use of the dynamically varying response function appears to give improved results. Moreover, in the example illustrated, routing of the runoff through a hypothetical reservoir appears to be unnecessary.For pervious areas, a method is suggested whereby the runoff coefficient is varied as a function of the time-dependent storage potential in the soil. For events with modest rainfall abstractions, the method appears to give good agreement with observed runoff hydrographs, but inclusion of a routing process through a cascade of reservoirs seems to be necessary in this case. Key words: computer, design, hydrology, rainfall, rational, runoff.
Computer-automated synthesis of building frameworks
Authors: Grierson Donald E. , Cameron Gordon E.
Published: January 2010

The paper surveys recent work carried out at the University of Waterloo concerning the computer-automated synthesis of minimum-weight planar steel frameworks. For any number of applied loading schemes, the design of the structure may be constrained by a variety of service and (or) ultimate 'limit-states' performance criteria concerning stresses, displacements, and (or) plastic collapse loads. Fabrication conditions can be imposed to ensure member-continuity and structure-symmetry requirements. Member sizes can be taken as either continuous or discrete variables to the synthesis process, depending on whether custom or commercial-standard sections are available for the design. In the latter case, the structure may be automatically sized using the standard sections specified by a variety of different steel design codes (to date, Canadian Institute of Steel Construction (CISC) and American Institute of Steel Construction (AISC) sections have been investigated).The computer-based design method is iterative in nature and is remarkably effective and efficient. Commencing with an arbitrarily chosen initial 'trial' design, the synthesis process determines the 'minimum-weight' structure satisfying all of the imposed performance and fabrication conditions without further designer intervention. The number of iterations required to achieve the optimal design is generally small and almost totally independent of the complexity of the structure.Three different designs of a building framework are presented to illustrate the scope of the method: limit-states design using CISC sections; working-stress design using AISC sections; and design under elastic and plastic performance criteria using custom sections. Key words: steel, frameworks, standard sections, custom sections, synthesis, minimum weight, limit states, computers, automated.
Identifying mode choice constrained urban travel market segments
Authors: Wilson F. R. , Stevens A. M. , Robinson J. B.
Published: January 2010

A new travel choice decision context and urban transport market segmentation is proposed. The research addresses the issue of the definition and measurement of captive/chooser market segments in the Regional Municipality of Ottawa–Carleton. It deals with the questions of mode choice for the work trip to the downtown core of the City of Ottawa, an area of particular concern to the transportation planners and decision makers of that region. Based on the necessity that an individual place himself in a position to perceive alternatives, a conceptual decision process for individuals is proposed. In the general case it is hypothesized that the urban transport market for a given alternative may be segmented into four groups of users across a continuum of choice. The four groups are referred to as the choice set hierarchy and represent populations of mode users with different potentials to change their mode of travel. Each of the market segments is sensitive to different kinds of transport system management (TSM) policies, and the research aims at developing a technique that might facilitate the development of baseline estimates of the impact of different policies on the urban transport system. Using a case study approach based on workplace surveys taken in the downtown core of Ottawa and involving only mode choice for the work trip, researchers successfully identified a simplified two-group market segmentation based on choosers and captives to given modes. In addition, using the same data base and objective responses to questions in the survey, a four-group choice set hierarchy market segmentation is also successfully identified. Trip-related and traveller-related data provided by the respondents are examined using analysis of variance techniques, and significant differences in characteristics between each of the four-group market segments are identified. Key words: transportation models, travel demand, urban transportation, market segmentation, mode choice.
Strength and structural safety of long-span light wood roof trusses
Authors: McMartin K. C. , Quaile A. T. , Keenan F. J.
Published: January 2010

Seventy-five light wood roof trusses were tested to failure in order to evaluate their safety and serviceability, and to examine the effects of size (members and spans) and load distribution (balanced and unbalanced) on truss performance. Two spans were tested: 21 m (45 trusses) and 12 m (30 trusses). It was found that the trusses were not consistent in their ratios of failure load to design load. Failures in the low-strength trusses included shear in the heel region of the top chord and tension in the scarf-cut bottom chord. It was subsequently demonstrated that these weaknesses could be removed through improved heel detailing. Key words: wood, trusses, strength, stiffness, safety, truss plates.
Remote semiautomatic instrumentation for intermittent streamflow measurement and suspended sediment sampling
Authors: Honsaker John L. , Campbell Ian A. , Bryan R. B.
Published: January 2010

Stream discharge and suspended sediment in ephemeral channels are measured by battery-powered instruments adapted for control by detection of rainfall. Solar cells recharge batteries between flow events. Key words: instruments, ephemeral channel, intermittent stream flow, suspended sediment, rain-activated, solar battery charging.
Seismic design forces for cylindrical tanks on ground
Authors: Tso W. K. , Ghobarah A. , Yee S. K.
Published: January 2010

A study is made on the hydrodynamic effect caused by seismic ground motions on the design of cylindrical on-ground liquid-storage tanks. The current techniques for determining the design base shear and overturning moment of the tank are reviewed, first treating the tank wall as rigid and then including the wall flexibility effect. By means of examples, these calculations are compared with those suggested by the National Building Code of Canada (NBCC). In addition, theoretically predicted values are compared with experimental data.It was found that in the case of tanks of high height to radius ratio and small wall thickness to radius ratio, the interaction of the fluid and wall flexibility can cause responses as high as two to three times those calculated based on rigid tank wall assumptions. The range of tank geometries under which the tank can be considered rigid is given. It is shown that the NBCC formula to establish seismic loads for tanks on ground is in general conservative, provided the acceleration ratio in the NBCC formulae takes on the value of maximum peak ground acceleration of the site. Key words: seismic, earthquake, hydrodynamic force, response, cylindrical tanks, design code.
Analysis of skewed multibeam bridges by the transfer matrix method
Authors: Buckle I. G. , Lee Weng-Onn
Published: January 2010

The analysis of multibeam bridge decks is seriously complicated by the effect of skew. Conventional methods invoke grillage solutions, which have inherent difficulties. This paper proposes an extension of the transfer matrix solution for right decks to include the effects of skew without detracting from the simplicity of the method. Both the flexural and torsional flexibility coefficients need to be modified for the skew support conditions and a new flexure–torsion coefficient is introduced to represent the cross-coupling that occurs between these flexibilities because of skew. The assumption of load transference through a single-point hinge between adjacent beams is retained, but the spanwise location of this point is varied from beam to beam according to the degree of skew. Results are presented for a range of skew angles and span/width ratios and compared with those from a modified grillage solution; excellent agreement was demonstrated up to and including 45° skew. Key words: highway bridges, skew, transfer matrix analysis, grillage modelling, multibeam decks, single span, comparative solutions.
Ultimate strength of three reinforced concrete highway bridges
Authors: Buckle I. G. , Dickson A. R. , Phillips M. H.
Published: January 2010

The destructive testing of three reinforced concrete highway bridges, recently made redundant by road realignment, is summarized. The procedure used to test the bridges to ultimate conditions is described and load capacities of about 20 times class 1 axle loads are reported for all structures. Analyses based on conventional ultimate strength theory can account for only two-thirds of these ultimate loads and then only if second order effects are included. A nonlinear finite element computer program has been developed and used to analyze one of these structures. Excellent prediction of the ultimate load is made by the program. It is therefore suggested that compressive membrane action, which is automatically modelled in the finite element solution, plays a significant role in the enhancement of load capacity.The paper concludes that a more sophisticated approach to the assessment of bridge load capacity is necessary if realistic estimates of actual strength are to be made. Limited experience with a nonlinear finite element program suggests one such approach. If used with care, some relief to the bridge replacement program can be expected. Key words: highway bridges, ultimate load capacity, finite element analysis, reinforced concrete, field testing, compressive membrane action.
Interaction of shear and tension in welded truss connections
Authors: Dawe J. L. , Pond B. S. , Grondin G. Y.
Published: January 2010

In many truss joints consisting of double-angle web members welded to stems of inverted lower chord tee sections, adequate fillet weld lengths may be provided without the need for gusset plates. In such cases where a joint may also be subjected to high combinations of shear and tension, the possibility of overstressing of a tee stem exists. In the investigation of this problem, four analytical techniques, including two proposed herein, and experimental results of 30 full-scale specimen tests, 22 of which were conducted during the investigation presented herein, are presented and evaluated. Analytical and experimental results indicate that the interaction of shear and normal stresses is an important consideration in the design of such joints and that an interaction check is required.Of the many parameters investigated as part of the experimental investigation, the two that most significantly influence the magnitude of tension force that a lower chord can simultaneously carry are the magnitude of applied shear force averaged over the available web shear area and the joint configuration itself. The inclination of a diagonal web member as well as intentional joint eccentricities have little effect on the strength of these joints, although joint ductility appears to be affected by eccentricities.Although all four analytical techniques have similar overall accuracies of prediction, a method based on applying a von Mises criterion at ultimate to determine an equivalent shear area in a tee chord is recommended as being the most suitable. Based on this method, as verified and validated by comparison with extensive experimental results of tests on full-scale specimens, a simplified design curve and associated equations are developed and proposed for design office use. Key words: connection, interaction, shear, tension, welded, truss.
Strength and structural safety of long-span light wood roof trusses. Reliability analysis using safety index
Authors: Salinas J. J. , Gillard R. G. , McMartin K. C.
Published: January 2010

The results of the full-scale testing, previously carried out, of 75 light wood trusses are analysed to evaluate their compliance with strength and serviceability requirements. Size effects were studied considering span length and chord size. Test data were grouped into 15 case studies according to span lengths, chord size, and mode of failure. For the study of a strength limit state, the safety index, β, was calculated for a range of values of the ratio of maximum lifetime to nominal snow load. For the study of a serviceability limit state, the safety index was calculated for a range of values of allowable mid-span deflection as a function of the span. A size effect was observed for both span length and chord size. Short-span trusses with small chords exhibited acceptable levels of safety when their strength safety index is compared with recommended target values. Long-span trusses with large chords, with an improved heel joint detail, exhibited values of β slightly below target values. All trusses showed acceptable levels for the safety index for the serviceability limit state. Key words: safety index, serviceability, size effect, strength, structural reliability, wood trusses.
Behaviour of a simple column base connection
Authors: Picard A. , Beaulieu D.
Published: January 2010

This paper presents the results of an experimental investigation on the behaviour of steel column base connections. The connection is effected by means of a steel base plate welded to the lower end of the column and attached to the concrete footing with two or four anchor bolts. The testing program comprised 15 specimens. The measured moment–rotation curves were used to determine the fixity factors of the base connections, taking into account the presence of an axial compression load.The results indicate that the compression force in the column significantly increases the flexural stiffness of the base connection and that the rotational restraint offered by the column base is sufficient to be considered in design. The results also show that the method of analysis used to determine the ultimate moment capacity of the base connection is conservative. Key words: steel column, column base connection, moment–rotation curve, anchor bolt, flexibility factor, fixity factor.