bluuebunny/crossref_metadata_2025 huggingface dataset:
Two moment structural safety analysis
Authors: Turkstra Carl , Daly Michael J.
Published: January 2010

In this paper the two moment criteria proposed by Hasofer and Lind, Paloheimo and Hannus, Ditlevsen and Skov, and the European Joint Committee on Structural Safety are reviewed. Numerical results for several examples are presented and compared. Special attention is given to situations involving counteracting forces where serious difficulties with simple approaches are demonstrated. The problem of design with specified indices is discussed briefly through two examples. It is concluded that simplified criteria may often be used but that a more basic approach must be followed in certain situations.
An overview of Canadian code requirements for earthquake resistant concrete buildings
Authors: Uzumeri S. M. , Otani S. , Collins M. P.
Published: January 2010

After briefly reviewing the need for earthquake resistant construction in Canada, this paper summarizes the development of the Canadian code provisions for seismic design 'loads.' Canadian code provisions for detailing earthquake resistant concrete buildings and the manner in which some of these provisions are applied in practice are then described. A statement of the specific Canadian problems that still need to be solved conclude the paper.
The effects of wall out-of-plumbs on the stability of core-braced buildings
Authors: Beaulieu Denis , Adams Peter F.
Published: January 2010

Reinforced concrete walls in core-braced buildings are erected with unintentional deviations from the vertical. The gravity loads acting through the out-of-plumbs of the core walls could induce significant moments, torques, and deflections in the core. This paper contains an assessment of these effects in typical core-braced buildings. Design equations are derived from the theory of statistics, using the results of measurements taken on three tall core-braced buildings under construction.
A three-dimensional model of Hamilton Harbour incorporating spatial distribution of transient surface drag
Authors: James William , Eid Basem
Published: January 2010

This paper discusses the formulation of surface boundary conditions for a three-dimensional transport model for shallow lakes, specifically for Hamilton Harbour. The same hydrodynamic equations that describe the circulation of the ocean and the Great Lakes were used in this study. However, the boundary conditions (bed topography, shoreline configuration, and surface and bottom shear stress fields) have bigger effects on circulation in shallow enclosed lakes.In this study the flow is assumed to be incompressible and in hydrostatic equilibrium. A layered system is used in which the lake is considered to consist of a number of unequal layers in the vertical. The hydrodynamic equations are integrated vertically over each layer, and both vertical and horizontal eddy viscosities are introduced.The over-water wind stress is determined using the logarithmic wind velocity distribution and Von Karman's integral equation for turbulent flow over a rough movable surface of variable roughness, in conjunction with equations for wind–wave generation. Thus the wind drag coefficient is determined as a function of wind and wave characteristics, and is time- and space-dependent.
Duration of load and probability of failure in wood. Part I. Modelling creep rupture
Authors: Barrett J. D. , Foschi R. O.
Published: January 2010

Two models are considered for the study of wood creep rupture behaviour and the associated load duration effects on strength. Both are damage accumulation models. In model I, the damage rate is expressed as the product of a stress-dependent factor and a damage-dependent factor. In model II, the damage rate is given as the sum of a stress-dependent term and a damage-dependent term. Both models consider a stress threshold below which the damage rate vanishes. For each model, stress histories corresponding to two types of tests are considered: a step function load test and a ramp load test. The predictions of the models for these two cases are used to obtain model parameters by fitting constant and ramp load test data. Data used correspond to small, clear specimens of Douglas-fir in bending. As an application, the problem of residual strength in a ramp load test after a time of constant load is discussed.
In-plane buckling of steel trusses
Authors: Csagoly Paul F. , Bakht Baidar
Published: January 2010

The usual method for determining the in-plane buckling strength of steel trusses consists of determining the buckling loads for the individual compression members with an assumed degree of fixity at the ends of each member. The paper shows that a steel truss can buckle not only through the buckling of one of its compression members but also through the instability of one of its joints. It also shows that the end fixities of various members of a truss, which are functions of applied loads, cannot be determined in isolation, i.e., without considering the whole truss.A computer based iterative technique is presented for determining values of rotational restraints at the ends of truss members, and also for determining the buckling loads for individual compression members and joints of the truss. The method, which is implemented through a computer program, has been validated against model test results. It is expected that by using this method the reserve of strength in existing steel truss bridges, which results from designs based on approximate methods of analysis, could be realistically evaluated and utilized to allow the bridges to be used to their full capacity.
L'utilisation des résidus des mines d'amiante comme granulats dans les bétons
Authors: Pigeon Michel
Published: January 2010

Preliminary studies having shown that it is possible to use the solid part of various asbestos tailings as concrete aggregates, a complete study of two tailings considered particularly suitable for this purpose was undertaken. The dust was first removed from the tailings, and these were submitted to the usual tests (absorption, sulfate soundness, etc.). The tailings were then used to make concretes that were later compared to concretes made with normal aggregates from the Quebec City area. These tests showed that the tailings could be used as aggregates, but that the quantity of cement paste required to obtain a given slump was much higher than that of normal mixes. The making of concrete with asbestos tailings as aggregates was thus found to be uneconomical. The concrete s made with the tailings were also found to be much more deform able than normal concretes. [Journal translation]
A field study of longitudinal dispersion
Authors: Beltaos S. , Day T. J.
Published: January 2010

The results of a comprehensive longitudinal dispersion experiment in a stream with an irregular, sinuous pattern are presented. The time-spread of tracer clouds was found to increase at a rate between [Formula: see text] as found for uniform prismatic channels, and x as found for highly irregular mountain streams. This ‘intermediate’ dispersive state is thought to be related to the stream’s degree of nonuniformity. The accuracy of one-dimensional approaches is considered, as is the applicability of a similarity analysis. A new definition of a 'mixing' length, based upon the condition of identical but shifted concentration–time curves, is proposed.
Strength of cold-formed steel shear diaphragms
Authors: Fazio Paul , Ha Kinh , Chockalingam S.
Published: January 2010

The design of light-gage steel corrugated shear diaphragms is not yet covered by the structural codes of many countries, including Canada. The shear capacity of steel diaphragms may be predicted by various approaches currently available, namely, those proposed by: (1) the American Iron and Steel Institute; (2) the Manual of seismic design of buildings, published by the U.S. Departments of the Army, Navy, and Air Force; and (3) the recommendations outlined in the current British code. In this paper, a rational method is proposed and the application of all the above methods is illustrated with reference to a specific example. Finally, the shear strengths of many diaphragms are predicted by the new approach developed by the authors and the results are compared to test data.
Effect of thermal insulation and heat sink on the structural fire endurance of steel roof assemblies
Authors: Stanzak W. W. , Konicek L.
Published: January 2010

Designing for energy conservation in buildings calls for considerably better insulated roof structures than have been used and fire tested in the past. This requires that information be developed on the effect of such increased insulation on the temperature of structural steel and steel roof decks during a fire exposure.Fourteen small-scale fire tests are summarized that show that for combustible and noncombustible insulating materials a critical thickness exists beyond which additional insulation does not increase the temperatures developed on structural steel.
Application of a simplified method of calculating longitudinal moments to the Ontario highway bridge design code
Authors: Bakht Baidar , Cheung M. S. , Aziz T. S.
Published: January 2010

A manual method for calculating the design live load longitudinal moments in superstructures of most right bridges is presented. The bridge types that can be analysed by this method are: slab bridges, beam and slab bridges incorporating both steel and concrete beams, bridges incorporating wooden beams, and slabs on hollow trapezoidal or other such torsionally stiff beams.The proposed method was developed by orthotropic plate theory, and was checked by the grillage analogy method. The basis of the method and details of development methodology are presented. The effect of the various parameters on the transverse distribution of longitudinal moments is discussed.The method is useful not only for the ease with which design longitudinal moments can be obtained, but also because it enables the designer to investigate the effects of making changes in the design on distribution characteristics.To demonstrate the simplicity of the solution a worked example is included.
Connection capacity of new Griplam nails
Authors: Fox Selwyn P.
Published: January 2010

The ultimate tensile strength requirements of Griplam nails (glulam rivets) were changed by the 1976 edition of CSA Standard 086. This action reduced the working loads for the nail-yielding mode of connection failure by 8%. To verify that the adopted factor of safety against yielding was retained, 12 large connections varying in predicted tensile capacity from 42–126 kips (187–560 kN) were tested. A bending specimen was chosen that served very well in three of the four load levels. The tests confirmed the predicted ultimate capacity of 1400 lbf (6230 N) per nail for a 3 in. (76 mm) or more penetration of dry Douglas-fir wood with loading parallel to grain. Other related aspects are discussed.
Automated high-stacking warehouse structures
Authors: Springfield J.
Published: January 2010

This paper briefly describes the salient features of automated warehouses as they affect the structural engineer. The two basic types, a separate building and rack structure and an integrated rack – building structure are discussed. The effects of pallet type, tolerances, loading, and rack standards on the structural framing are considered.
Computer graphics in nonlinear design problems
Authors: Gross John L. , Mutryn Thomas A. , McGuire William
Published: January 2010

The purpose of this paper is to describe an interactive computer graphics approach to the analysis and design of structures exhibiting nonlinear structural behavior. A general procedure for the nonlinear analysis of planar frame structures, which accounts for member yielding, is described. In addition, the graphics programs required to input an arbitrary planar structure, monitor the analytical procedure, and aid in evaluating the results of the incremental analysis are presented. A procedure for generating a color image of the deflected structure, where the color indicates the proximity to yield, is also presented. This interactive approach to a powerful analysis procedure, aided by graphic interpretation of input and analysis results, provides a practical desïgn tool.
Preliminary design of precast, segmental box-girder bridges using optimization
Authors: Miller Craig J. , Accioly Juarez
Published: January 2010

Precast, prestressed segmental box-girder bridges are now accepted as an economical alternative for spans over 150 ft (46 m). Decisions about cross-sectional dimensions made during preliminary design can have a substantial influence on the final cost of the bridge. To help the designer obtain an economical starting point for a final design, a program was written to determine section dimensions and midspan and pier prestressing steel areas to give minimum cost. Since a preliminary design is obtained, the analysis techniques and design criteria have been simplified to reduce computation. The design produced by the program will satisfy AASHTO specification requirements and the recommendations of the PCI Bridge Committee. The optimization algorithm used is the generalized reduced gradient technique. To demonstrate the program capabilities, three example problems are discussed. The results indicate that optimum span-depth ratios are approximately 24 for the cost ratios used. The cost of the optimum design does not seem to be too sensitive to the ratio of concrete cost to prestressing steel cost.
The Edmonton–Calgary corridor transportation study
Authors: Mayne John W. , Morrall John F.
Published: January 2010

The Edmonton–Calgary corridor transportation study is an example of multimodal intercity passenger transportation planning in a low-density corridor. This represents a departure from most corridor studies, which have been conducted in the most intensively travelled and densely populated regions. The study provided the background data, information, and analysis to facilitate transportation planning in the Edmonton–Calgary corridor region. A wide range of capital-intensive alternatives (particularly for the rail and air modes) and a number of transportation system management alternatives are related to transportation issues in the corridor region in a multimodal systems analysis framework.This paper discusses a number of unique approaches used in the study that were the result of the need to deal with the low-density aspects, the need to consider both regional and intercity travel, and the inherent design of the study. These include its iterative approach to the analysis, its handling of the demand and cost analysis, its consideration of multimodal impacts, and the emphasis on identifying key issues and resulting strategic choices. The success and drawbacks of these methodologies are reviewed.The paper also reviews the major findings of the study, many of which can be extended to a more general context: a competitive market analysis may be of little interest in low-density regions; new technologies tend to bias even further the imbalance between intercity and regional transportation service; the automobile has a key role to play in regional transportation; for many transportation needs the intercity bus is an economical and efficient mode; and an improved rail service is an uncertain and long-term venture, which could detrimentally affect all intercity bus service in the region.
An accident-rate and severity-ratio quality-control technique for identifying hazardous roadway locations
Authors: Fleming D. S. , Fiander A. D.
Published: January 2010

Budgetary constraints have initiated development of several schemes for establishing roadway-improvement priorities. Inherent in most of these programs is a technique for identifying the most appropriate roadway locations requiring improvements. In the past, except for situations where capacity limitations are evident, safety has generally been the criterion used to justify roadway improvements. Therefore, those roadway locations that are relatively the most hazardous and most susceptible to improvement must be identified.Quality-control techniques were first applied for this identification purpose over 20 years ago. However, most applications have been associated with accident-number or accident-rate data. Use of accident-severity criteria in quality-control methods is still vague. This paper provides an overview of existing identification techniques. Further, by defining severity as the ratio of fatal and injury accidents to all accidents, a severity quality-control technique for identifying hazardous roadway locations is presented. This technique incorporates both accident-rate and accident-severity criteria.
Simplified analysis of cold-formed steel shear diaphragms
Authors: Chockalingam S. , Ha Kinh , Fazio Paul
Published: January 2010

Research carried out on light-gage metal shear diaphragms clearly indicates that the shear behaviour depends mainly on the behaviour of the fasteners. There is no generally accepted theory to predict the shear stiffness and strength of diaphragms with welded connections, even though there exist some approximate methods for the case of diaphragms with mechanical fasteners. Simplified formulas are presented in this paper for calculating the shear stiffness and strength of metal shear diaphragms. The analysis is based on the observed deformation pattern of the panels and on the failure mode of the fasteners. By using the test data of the fasteners, the shear characteristics of many diaphragms are predicted and compared with the test results. It is of interest to note that the proposed formulas are suitable for diaphragms with any types of fasteners. Because of their generality and simplicity, the theory would be extremely useful for design engineers.
Control of construction loads on multifloor buildings
Authors: Gardner N. J.
Published: January 2010

This paper collects together relevant information and develops a methodology to control construction loads in multistorey buildings taking into consideration member gain in strength with age and temperature.Many multistorey buildings are constructed by casting on to forms that are in turn supported on the previously cast lower floors in the building. The loads imposed upon these recently cast supporting floors during construction may exceed the strength capabilities of these floors. The strength capabilities of the concrete structural elements are dependent on age and curing temperature, which must be considered in the design of any construction schedule.One conclusion drawn from the method is that the greater the number of forms used the greater the construction load applied to the slabs. Hence, it is recommended that only one level of forms plus reshores be used for all multiform construction.During the form-stripping–reshoring operation it is necessary that at least a complete bay and preferably a complete floor be cleared of forms before any reshores are installed.
Refined calculations for the strength and stiffness of cold-formed steel diaphragms
Authors: Ha H. K. , El-Hakim N. , Fazio P.
Published: January 2010

A refined yet simple method is presented for the analysis of cold-formed metal shear diaphragms. Expressions for the deflections and fastener forces are developed based on an assumed mode of deformation in conjunction with a refined set of internal force distributions. The formulas are applicable to both 'direct' and 'indirect' shear-transfer cases. The generality and the accuracy of the derived expressions are illustrated in an application of the method to the analysis of eight diaphragms having a wide range of constructional details. The results of calculations for the diaphragm flexibility and strength are in good agreement with test results and with finite-element analyses.
Practical design (aseismic) of steel structures
Authors: Degenkolb Henry J.
Published: January 2010

Structural design to resist earthquakes is different from structural design for the more usual forces in that the loads are uncertain but much larger than the elastic resistance of the structure; consequently, the engineer must be concerned with cyclic postelastic performance of materials and systems, ductility, and the stability of structures near ultimate loads.Cyclical tests on members and connections for steel moment-resisting frames indicate very stable hysteresis in the plastic range, a very desirable characteristic. Moment-frame structures, however, are subject to large deflections with consequent damage to the point where secondary effects such as P-delta may become critical. Some observations have indicated that better performance can be obtained by combining the ductile steel frame with concrete shear walls or with steel-braced frames. Tests, both in Japan and California, suggest that large amounts of energy can be absorbed and large ductilities can be achieved by using eccentric connections with steel-braced frames.
Operational hydrology with forecasting for a multireservoir water resources system
Authors: Thompstone Robert M.
Published: January 2010

One of the tools used by the water resources engineer in developing operating strategies for water resources systems is operational hydrology—the stochastic modelling of a hydrologic phenomenon such as river flow in order to generate a large number of possible future occurrences of the phenomenon. This paper describes the selection and parameter estimation of a multisite multiseason model for application to five sites of a hydroelectric system operated by Alcan Smelters and Chemicals Limited in the Saguenay – Lac St-Jean region of Quebec. The model is used to generate synthetic inflow data and compute corresponding forecasts. The model is evaluated with respect to its ability to both generate realistic synthetic data and produce meaningful forecasts.
A program package for interactive design of optimal pipe networks for any climatic region in Canada
Authors: James William , Robinson Mark A.
Published: January 2010

The program package presented in this paper facilitates the computer-aided design of least-cost pipe distribution networks for any region in Canada. The design algorithms function in an interactive, conversational mode. Three algorithms—for analysing pressure and flow in networks, for computing the 'best' diameter of each pipe in the network, and for computing the best sizes of devices and materials to protect the pipes against freezing—were combined. Here 'best' is taken to be the least equivalent average annual cost.The pipe distribution network may include a wide variety of pipeline components and environmental constraints. The variables that determine the cost of pipe distribution networks in the extreme climatic regions of Canada are identified and their interaction for the many combinations of environmental, economic, and technological constraints are described.The computer program package was employed in the design of a minimum-cost distribution system for Broughton Island, Northwest Territories. The performance of the package indicated that it could be reliable, easy to use, and competitive in design cost.The package is locally accessible through a national computer network to dial-up terminals in or near most cities in North America.
Computer usage in structural building design—a Canadian survey
Authors: Carson Daniel J. , Hartley Gilbert A.
Published: January 2010

Today a majority of consulting engineers engaged in the structural design of buildings in Canada employ the computer as an aid to analysis and design. The behaviour and attitudes of these consultants toward the computer are reviewed here and the nature and extent of computer usage are discussed. This survey was carried out by means of a mailback questionnaire. Differences in usage between Canadian and American consultants are indicated.
The Eskimo Point water supply program
Authors: Foster R. R. , Parent T. J. , Sorokowski R. A.
Published: January 2010

Eskimo Point, Northwest Territories, is a predominantly Inuit community of about 900 people, located on the west shore of Hudson Bay. Formerly, its water supply was obtained from nearby small, sometimes polluted, shallow lakes, which freeze to the bottom in winter, necessitating an ice-cutting operation. In 1973, a study was undertaken to investigate alternative methods of improving Eskimo Point's water supply. The recommended solution was the construction of a 6 500 000 gal (29 548 350 L) earth fill reservoir, lined with a hypalon membrane.Further field investigations and detailed design of the facility were carried out in 1974. All long-term delivery items were pre-ordered, and a general contractor was selected through public tender. Utilization of local manpower and equipment was specified.Construction commenced in mid-June of 1975 with the contractor providing on-the-job training to local Inuit, who adapted quickly to the equipment. Within 2 weeks, an all-local labour force was working around the clock constructing the reservoir embankments. Placement of a membrane liner of approximately 3.5 acres (1.4 ha) took 1 week, and was followed by placement of a protective layer of fill over the liner. Through good cooperation among owner, supplier, contractor, and engineer, the reservoir was completed in the fall of 1975 in time to be filled with water from a lake approximately 1 mi (1.6 km) away.
Systems analysis applied to the St. John River
Authors: McBean Edward A. , deLucia Russell J.
Published: January 2010

The difficulties and capabilities of mathematical models as applied to the problem of derivation of a detailed water quality management plan for the American portion of the St. John River are described. The international implications considered within the plan derivation are included.Specific attention is given to the iterative calibration efforts undertaken as part of the utilization of mathematical models. The relative magnitudes of the nutrient regime sources as derived from nonpoint and point sources are characterized.
Effect of computers on economy of bridge design
Authors: Bakht Baidar , Csagoly Paul F. , Jaeger Leslie G.
Published: January 2010

The paper examines highway bridge costs in relation to the costs of an overall highway system, divides the bridge costs themselves into various categories, and examines the feasibility of reducing the costs in these various categories by adopting computer-based methods of design. The conclusion is drawn that appreciable savings are available in the cost of materials in construction, and that these savings greatly outweigh any possible increase in design costs needed to bring them about.The paper also considers the effect of computer-based design on safety margins in the resulting bridges, and examines briefly the roles of the engineering profession and the drafters of code specifications in influencing designers towards adopting computer-based methods.
Estimating ungauged streamflow using principal components
Authors: Fuller G. A.
Published: January 2010

A principal components regression model for estimating ungauged streamflow data has been tested. This model overcomes the computational problem that may develop in a conventional least squares model when the determinant of the correlation matrix approaches zero. The parameters required by the model are estimates of the means and standard deviations of flows at the ungauged site and estimates of correlation coefficients between flows at the ungauged site and nearby hydrometric sites. These parameters were obtained from least squares models using physiographic characteristics as predictor variables. The model was tested by estimating streamflow records assumed to be nonexistent. These tests show that, while eliminating the possibility of the computational problem, the principal components model estimates are similar to those from a conventional regression model. Consequently, the principal components model is more reliable for highly correlated predictor variables. An example is given to illustrate the use of the principal components model.
Comprehensive strength analysis of framed sandwich panels
Authors: Rizzo S. , Fazio P.
Published: January 2010

Local instability of thin facings in sandwich panels often leads to wrinkling at stresses lower than yield stresses. An investigation was carried out by the authors on the behaviour of the facings of rectangular sandwich panels having thin aluminum faces and styrofoam core when subjected to edgewise compression and (or) out-of-plane bending. A set of the panels had no additional reinforcement at the edges whereas others were either totally or partially reinforced with wood framing integrated along the edges. Existing formulae developed to predict these stresses were found to overestimate results obtained from a test programme conducted by the authors. New expressions are presented for wrinkling and ultimate loads for sandwich panels with various edge conditions. A comparison is made between existing and newly derived expressions.
An overview of the construction of heliports on offshore lighthouses
Authors: Danys J. V.
Published: January 2010

Up until the 1950s, government ships were the only means of servicing offshore lighthouses. Early in the 1960's, the Canadian Coast Guard started to use helicopters to service all their isolated lighthouses. A helicopter transports people and replacement parts for navigational aids at a fraction of the time and cost required by a ship. Now all major offshore lighthouses are being built with heliports; in addition, heliports are being erected on some old lighthouses.Heliports on offshore lighthouses are private, exclusive-use heliports for light and medium helicopters. Their size is the minimum safe size for the helicopter landing.In designing offshore heliports, consideration is given to easy and economical construction procedures; the supporting structure of a heliport is light or made of light members for easy erection.
Consolidation of urban goods movement—some economic aspects
Authors: Sargious M. A. , Wang T. C. , Morrall J. F.
Published: January 2010

The present system for pick-up and delivery of small shipments by trucks within an urban area is not very efficient. This is often due, in part, to poor vehicle utilization, competition between freight and passenger movements using available common right-of-way, highly congested and dense city centres, and current business practices. The lack of coordination between truck shipment activities often leads to route duplication, street congestion, long waits at loading/unloading facilities, and underutilization of available truck capacity.Because provision of consolidation terminals appears to be one of the promising alternatives for alleviating some of the problems of the current freight distribution structure, this study has been undertaken to gain better insight into the feasibility and desirability of this alternative. For this purpose, the City of Calgary, which had a population of 500 000 in 1977, was chosen for identifying the economic benefits of applying the concept of consolidation terminals operation to the movement of small shipments within the city. The results revealed that a system with a single consolidation terminal located at an appropriate site is economically feasible and would significantly reduce the number of trucks and truck trips needed for urban goods movement.
Behaviour of limited prestressed beams under repeated loads
Authors: Kulkarni G. G. , Ng S. F.
Published: January 2010

This investigation deals with the flexural and serviceability behaviour of limited prestressed beams under repeated loads and considers the concrete in the tension zone by relating the distribution of stresses in steel at and in between cracks. The consideration of crack stability and bond efficiency in achieving additional load-carrying capacity and the resulting economy are discussed from design considerations. The widening and deepening of cracks and their overall stability under severe conditions of repeated loading were studied by tests on limited prestressed beams having different distributions of steel and the results were used for comparison. The destruction of the bond between concrete and steel located between adjacent cracks under repeated loads was investigated in detail and the results were interpreted from endurance limit considerations. Theoretical analysis included computation of deflections and moments by considering the concrete located in the tension zone. Effects of repeated loads on load deflection hysteresis, crack pattern and stability, efficiency of bond between steel and concrete between adjacent cracks, contribution of concrete in tension towards increase in rigidity of beam, and endurance limit for working moments, stresses in steel and concrete expressed as percentage of ultimate are discussed in detail. It is seen that this method of accounting for the strength of concrete in the tension zone closely predicts the behaviour of beams.
Interaction of shear and tension in welded truss connections
Authors: Walton Byron A.
Published: January 2010

By present design procedures bottom chords of welded structural steel trusses are designed as simple tension members. Little regard is given to the interaction of shear and tension stresses that occur at the bottom chord joints. A study of this interaction on the ultimate capacity of a truss joint consisting of a structural tee tension chord and double angle web members is presented. Based on theoretical considerations and experimental results, an interaction equation is suggested as a design aid to determine the allowable tensile stress at critical joints with transverse shear present.
Theoretical analysis of haunch-reinforced T-joints in square hollow sections
Authors: Korol R. M. , Mansour M. H.
Published: January 2010

A theoretical analysis has been undertaken for unequal width T-joints, haunch-reinforced, in square hollow structural sections (HSS). The unreinforced joint is merely a special case. The theory was based on a finite difference solution to the elastic chord flange plate equation and predicts the branch-to-chord joint stiffnesses under both bending [Formula: see text] and axial force (C = P/δ). The effects of varying the width ratio λ, overall haunch length-to-width ratio λ1, and chord width-to-thickness ratio bc/tc were studied for different plate edge boundary conditions. The latter parameter has the greatest effect on stiffness, but the other two, including haunch size, are also significant. There is reasonable agreement between the joint rotational stiffness factor J, obtained from earlier tests, and the predictions of theory for different edge boundary conditions. The unequal width, unreinforced connection is generally too weak to be viable in design applications. Haunch stiffeners improve strength and stiffness, and are particularly beneficial for large rather than small λ (i.e., 0.833 vs. 0.333).
Probability considerations in assessing the effects of structural out-of-plumbs
Authors: Beaulieu Denis , Kelker Douglas , Adams Peter F.
Published: January 2010

Design expressions based on statistics have been derived in earlier papers to account for the destabilizing effects of the gravity loads acting through the random out-of-plumbs of members in structures. The reliability of the predictions and the soundness of the theory itself depend on the basic assumptions that the out-of-plumb variables are uncorrelated and that the loads are deterministic.An examination of the nature and implications of these assumptions is presented in this paper. Of particular interest is the determination of the final safety obtained for "out-of-plumb" effects when the design is based on the limit states technique prescribed by the Canadian Standard CAN3-S16. 1-M78. It is demonstrated that the expected probability of failure is increased due to the existing dependence between the out-of-plumbs of adjacent members but is reduced due to the randomness of the factored gravity loads. As a result, the final probability of failure appears to be somewhat lower than that implied by the probability factor used in the design expressions and seems to be appropriate for stability considerations.
Safety factors for fire loads
Authors: Lie T. T.
Published: January 2010

A mathematical model is described that enables the evaluation of the expected fire cost and life losses for buildings. Optimum safety factors for fire loads are derived by minimizing the fire cost expectation, subject to a constraint on expected life losses. A sensitivity study shows the important variables that determine the optimum fire load safety factor. Results are compared with code requirements and suggestions are made for improving fire resistance design from the point of view of safety and cost.
Proof testing of a noncomposite floor system
Authors: Ghosh Ram S.
Published: January 2010

A suspended concrete slab in a noncomposite floor system construction exhibited cracking in the upper surface, which was considered to be aggravated by the movement of heavy steel wheeled trolleys. A critical section of the floor was carefully instrumented for deflection and strain measurements and readings were taken with the heaviest service load at locations for maximum stress. The results established that the resulting induced stresses were relatively small, well below the allowable working values, which confirmed the prognosis that the complete floor was acting as an I-beam bridge structure. Accordingly, the floor was considered adequate to carry the 23.5 ton (21.3 Mg) moving trolley load.
Roof snow loads in Canada
Authors: Taylor D. A.
Published: January 2010

The National Building Code of Canada requires buildings to be designed to carry uniformly and nonuniformly distributed snow loads and the "Commentary on Snow Loads" in Supplement No. 4 to the National Building Code of Canada gives detailed design information. This paper discusses the material given in the 1977 commentary and supplements it with examples and photographs.
Carrying capacity of edge-compressed rectangular plates
Authors: Sherbourne A. N. , Haydl H. M.
Published: January 2010

The carrying capacity of simply supported rectangular plates under uniaxial, in-plane compressive loading is investigated. The ultimate load is determined as the load corresponding to the intersection of an elastic loading line and a rigid–plastic unloading line. An attempt is made to formulate a plastic roof mechanism for the rectangular plate; the square buckle pattern mechanism for long plates is obtained as a special case. The effective width method is re-examined and is shown to give good agreement with experimental evidence. The recommendations of CSA S136-1974 are briefly reviewed in the light of the results obtained.
Power spectral analysis of a forcemain failure caused by waterhammer
Authors: James William , Hennessy Robert R. , Disher Jerold W.
Published: January 2010

The 14 in. (0.36 m) forcemain followed an overall convex pipeline profile for 4000 ft (1200 m) and would be subject to negative surge problems associated with pump shutdown. The forcemain couplings failed three times near the pumphouse and the failure was thought to be related to waterhammer effects. The sequence of breakages is reviewed. A series of pressure recordings were then made over 14 days on the repaired forcemain, leading up to and including the final failure. These pressure recordings were digitized and subjected to power spectral analysis. The power spectra pointed out several significant events that were not evident from the pressure record alone.These included the fact that the original breakdown in the forcemain occurred several days prior to its ultimate failure and discovery on the surface. It was also determined that the break in the system was due to the apparent merging of the primary waterhammer wave with an existing but gradually changing lower frequency wave. This second wave was associated with rigid column motion and gradually increased its frequency. The resultant wave superposition collected sufficient energy at one point to cause the ultimate failure of the evidently already damaged forcemain system.Power spectral analysis proved useful as a method for analyzing waterhammer effects in a forcemain complicated by column separation, leakage, and vapour pocket collapse, and may be a useful way of monitoring the performance of longer pipelines.
Mathematical efficiency concerns in water distribution network considerations
Authors: Gupta Swapan , McBean Edward A. , Cousins J. Richard
Published: January 2010

Because the governing mathematical equations for water distribution networks are nonlinear, many computerized methods of solution have been proposed as the "best" method of solving these equations. A comparison of some of the more popular methods indicates that little difference exists between the methods, although a slight overall edge is available with the Newton–Raphson technique. The exponential increase in computer model cost with increasing network size is demonstrated. The utility of network schematization models is documented, particularly as employed in design studies.
Factored resistance of welded connections subject to shear and moment
Authors: Neis V. V.
Published: January 2010

The ultimate capacity of eccentrically loaded fillet-welded connections was experimentally determined by Dawe and Kulak. They proposed an analysis technique for such connections based on an assumption of rigid body rotation of the connection plate about the instantaneous center and the use of weld group load–deformation curves. The Canadian Institute of Steel Construction (CISC) published factored resistance tables for such connections based on this theory. Unfortunately, the theory and design tables can be subjected to the following criticisms : (1) the theory is complex and cannot be easily used for design purposes unless design tables are available; (2) the results from a modified theory were apparently used for comparison with the eight laboratory test results; and (3) the CISC design tables were obtained by using an analysis procedure that does not appear to satisfy all of the design code limitations given by CSA-S16.1-1974.In this paper the author examines the statical behavior of such connections. This study indicates that the overall effect of the last two points is not too serious. The author presents explicit equations approximating the factored load resistance. The use of these equations obviates the first criticism.The design equation developed in this study is very simple; it may be applied with ease in any system of units since it is essentially nondimensional; and it satisfies the specifications of the design code.
Significance of structural out-of-plumb forces and recommendations for design
Authors: Beaulieu Denis , Adams Peter F.
Published: January 2010

The effects of gravity loads acting on column and wall deviations from plumb in core-braced buildings have been investigated and expressions for the forces involved have been published in previous papers. The predictions obtained from the design expressions, as applied to two typical core-braced buildings, are compared in this article with corresponding actions resulting from wind and earthquake loads.This investigation aims at separating the effects that are significant in design from those that are small enough to be neglected. A set of simple rules to account for the out-of-plumb effects in buildings is presented as a possible complement to the existing recommendations on stability in the Canadian standard for steel construction CAN3-S16.1-M78.
Assemblages continus pour charpentes préfabriquées en béton armé
Authors: Picard André , Léger Pierre
Published: January 2010

This paper presents the results of an experimental investigation aimed at the development of moment connections for precast reinforced concrete members. Two types of moment connections were tested. Type 1 moment connections are made by welding reinforcing bars protruding from the column to a steel plate welded to the tension reinforcement of the beam. Type 2 moment connections are made by welding a continuity plate to two other steel plates, one welded to the reinforcement of the beam and the other affixed to the face of the column by means of studs. The testing program comprised 15 specimens including four monolithic joints of the same geometry as specimens of types 1 and 2, introduced to compare the behaviour of cast-in-place and precast structures.The test results indicate that type 1 moment connections have almost the same strength and stiffness as monolithic joints but are less ductile. In type 2 moment connections, brittle fracture occurred at bending moments much lower than the ultimate strength of the beams. Some modifications are suggested in the paper in order to improve the behaviour of the two types of moment connections.
Ultimate load behaviour of internally pressurized "cut-and-cover" type underground nuclear reactor containments
Authors: Mahrenholtz O. , Reddy D. V. , Ramamurti V.
Published: January 2010

The static and dynamic nonlinear response to internal pressurization, due to a loss-of-coolant type accident, is investigated for a "cut-and-cover" prestressed concrete horseshoe-shaped containment in a clay medium with and without a stiffening (concrete – foamed concrete) jacket. The loading conditions considered are: (i) sustained prestress only, and (ii) sustained prestress and static–dynamic internal pressure. The yield condition used is the Drucker–Prager criterion. Axisymmetric finite-element analysis is carried out for various media patterns (concrete – foamed concrete – clay) using the computer code NONSAP. The results indicate considerable increase in structural integrity due to embedment.
Impact of construction of a hydroelectric project on the water quality of five lakes in Nova Scotia
Authors: Kelly D. M. , Underwood J. K. , Thirumurthi D.
Published: January 2010

In February, 1975, a [Formula: see text] year study of five highland lakes (Big, Cheticamp, Gisborne, Long, and Surge Lakes) in the Wreck Cove area of Nova Scotia was initiated to determine the limnological effects of construction of a hydroelectric project. Almost 600 lake-water samples were used to monitor water-quality changes resulting from tunnelling, dam construction, reservoir clear-cutting, slashing, and burning, and establishment of access roads.The impact on Surge Lake was much more pronounced than on the other four lakes. Evidence strongly suggests that the significant water-quality changes in Surge Lake can be attributed to clear-cutting operations and construction activities (of longer duration and higher intensities in the vicinity of Surge Lake area in comparison with other areas) resulting in accelerated soil erosion, nitrification, and soil leaching. Also, the Surge Lake watershed had steeper slopes, and different vegetative cover.Nitrate, ammonia nitrogen, total and ortho phosphorus, calcium, magnesium, sodium, potassium, chloride sulfate, total solids, conductance, pH, suspended solids, and turbidity increased significantly in the lower-most lake (Surge) but only moderately in the remaining lakes. The relative rates and amounts of revegetation of exposed soils were also considered key factors in influencing the magnitude of changes in water quality of these highland (elevation 400 m) lakes.
The limitations and usefulness of streamflow generation methods: a case study
Authors: Stolte W. J.
Published: January 2010

Probabilistic models have become important hydrologic tools. However, increasing model complexity makes the connections between the model and the physical world more and more vague. This can lead to a de-emphasis of engineering judgment, since model validity is easily assumed when even partial verification must await future occurrences. A simple autoregressive model was used to generate stochastic flow sequences for the dam and reservoir being constructed on the Red Deer River in Alberta. The results from this model were compared with those obtained from a more complex autoregressive moving average (ARMA) model. Both models have similar deficiencies. It is concluded that since stochastic generation can never represent future conditions with certainty, the common practice of basing the hydrologic design of reservoirs on actually recorded data is usually the most valid procedure. However, stochastic streamflow generation can be used to give valuable probabilities of reservoir storage failure.