bluuebunny/crossref_metadata_2025 huggingface dataset:
Transient conditions in the transition from gravity to surcharged sewer flow
Authors: Hamam M. A. , McCorquodale J. A.
Published: January 2010

One of the least understood aspects of flow in sewers is the nature of the transition from gravity to pressure or surcharged flow. A complete design of a storm sewer should consider both gravity and surcharged conditions. The available design and/or simulation models can handle gravity (open-channel) flow with various degrees of sophistication, whereas some consider surcharged flow. None of the available stormwater computer models include an adequate treatment of the transient pressures associated with surges that can occur at the transition from gravity to pressure flow. During the transition period there is a further complication because there is a mixture of air and water in the pipe.This paper deals with transients that occur when gravity flow is suddenly changed to pressure flow by the occurrence of a surge in the line. The pressure head fluctuations associated with this transient have been studied. Some of the factors affecting the pressure transients are: pipe size, pipe shape, flow velocity, Froude number, relative depth of flow, alignment of the pipe, pipe material, venting arrangements, and boundary conditions such as pumps, interceptors, and drop pipes. The paper also suggests a theory to predict the excess pressure rise due to these transients. Keywords: Fluid transients, gravity flow, instability, pipe flow, sewers, surcharged flow, surges, two-phase flow.
Wave-induced sand ripples
Authors: Quick Michael C.
Published: January 2010

Development of sand ripples from a flat sand bed subjected to shallow water wave action is explained in terms of the unsteady kinematics of the sand particles that form the sand ripple. The steady kinematic requirements for a fully developed sand ripple are also specified, and are shown to be consistent with an idealized solution of the fluid velocity field near the sand bed. This idealized velocity field is a result of the interaction between the surface wave velocity field and the sand ripple shape. The velocity field is related to the sand transport rate by using an adaptation of Bagnold's transport equation for steady flow. Expressions are derived that define the maximum ripple height and wavelength in terms of the wave orbital velocity and sediment characteristics. Theoretical estimates are made of the vortex strength shed from the ripple crest and the role of this crest vortex is considered. Keywords: Sedimentation, sediment transport, waves, ripples, coastal engineering, hydrodynamics.
A proposal for the compatibility of static and dynamic seismic base shear provisions of the National Building Code
Authors: Tso W. K.
Published: January 2010

A comparison is made, based on static and dynamic base shear calculations according to the National Building Code of Canada of 1980, for four types of simple structures, namely, uniform moment resisting frame structures, uniform ductile flexural wall structures, uniform reinforced concrete shear wall structures, and unreinforced masonry wall structures. It is shown that a significant discrepancy exists between the static and dynamic base shear values, depending on the type and the fundamental period of the structure. The causes for the discrepancy and the necessity to make static and dynamic base shears compatible are discussed.
Rapid design of built-up I-shaped compression members
Authors: Azad Abul K.
Published: January 2010

A procedure is presented based on Canadian Standard CSA S16.1 for a rapid proportioning of a symmetrical built-up I-shaped compression member. The method considers the general case having different effective lengths in the two principal axes. The failure axis is not known initially. The method is design oriented and eliminates time-consuming trials to establish an economical section.
Preliminary design of the muskeg drainage system at Onakawana, Ontario
Authors: Muzik Ivan
Published: January 2010

Development of a lignite deposit at Onakawana in northeastern Ontario requires extensive drainage of the muskeg blanketing the proposed mine area. Dewatering of the muskeg is necessary prior to its stripping. Muskeg drainage systems must also efficiently handle surface runoff due to rainfall and snowmelt. A hydrological analysis of the muskeg and a hydrologic design for its drainage system are presented. Surface runoff quantities were estimated by means of the rational method and a kinematic wave model of overland flow. A modified Glover–Dumm equation was used to calculate the diteh spacing required for dewatering. A preliminary drainage system layout is discussed.
Elasto-plastic finite element analysis of welded truss connections
Authors: Lau William Chung-Ping , Dawe John L.
Published: January 2010

A finite element technique based on an incremental tangent stiffness method is employed herein to analyze the behavior of welded truss connections subjected to combined tension and shear. A computer program named ELAPLAS (ELAsto-PLAStic finite element analysis) is developed to simulate the load–deformation behavior and to predict the ultimate tensile capacity of a structural tee in a welded truss joint subjected to a prescribed transverse shear load. Analytical studies were carried out to investigate the interaction of tension and shear in welded truss connections. The analytical results obtained are compared with available test data to verify the validity of the proposed finite element technique. Results of parametric studies are presented to illustrate the significance of various design parameters in welded truss connections. Such parameters as material properties, thickness variations of structural tee web and flange, and the truss configurations are investigated. As a result of the present work, simple interaction equations of combined tension and shear are developed and suggested for design office use.
Probabilistic study of strength of reinforced concrete members
Authors: Mirza Sher Ali , MacGregor James G.
Published: January 2010

This paper documents the assumptions and analyses made in the derivation of resistance factors for reinforced concrete design compatible with the load factors in the National Building Code of Canada. Based on existing data on the variability of concrete and steel dimensions, statistical estimates were made of the variability of the strength of reinforced concrete members. These data plus statistical descriptions of loadings were used in a first-order, second moment analysis to compute resistance factors. These have been proposed for inclusion in the CSA A23.3 Code and are currently under study by the CSA Technical Committee on Reinforced Concrete Design.
Interactive processors for design use of large program packages
Authors: James William , Robinson Mark A.
Published: January 2010

Civil engineering design methodology is changing as a result of emerging computer hardware and software. Highspeed, interactive, user-friendly systems are more common, whereas formerly batch submission of batch-oriented programs was the only common method. However, a variety of large, complex program packages are still widely used for urban drainage design problems. These packages are usually executed on mainframes with a large memory capacity and high computing speeds; users need a good working knowledge of FORTRAN input requirements and mainframe job control language, especially when the packages are used in a multi-program, multiprocessor environment. Furthermore, long learning times are associated with the implementation and execution of complex packages on batch-oriented mainframes at remote sites.This paper discusses the design of an interactive package of pre- and post-processors to facilitate input data preparation, job execution, output interpretation, and job resubmission in a multi-program, multiprocessor, remote batch environment. The pre-processors create input data files for job execution; the post-processors operate on the output from the simulation package, synthesizing, analyzing, and plotting to accelerate the users' interpretation at their terminals. The important advance in this work is that the original coding for the main, externally supported, batch-oriented package is not altered. Furthermore, local text processing using previously prepared, disc-based outline reports and the post-processor output allows direct production of draft reports.
Predicting the strength of branch plate – RHS connections for punching shear
Authors: Davies Gwynne , Packer Jeffrey A.
Published: January 2010

The stress distribution in steel plates welded at right angles to either I-section or rectangular hollow section members is notoriously nonuniform, leading to early failure of the plate, tube wall, or weld. The paper proposes an upper-bound approach that combines lócal punching shear with normal yield line analysis. The resulting expression for strength and branch efficiency is seen to be sensitive to the value of tube wall slenderness, and in reasonable agreement with a previously obtained efficiency expression based on a lower bound to test results. The theory also confirms the experimental observation that the width ratio between the plate and the rectangular hollow section does not have a significant effect on the efficiency of the connection. The theory presented enables a parametric study of the joint strength and efficiency to be made, and thus leads to a greater understanding of the behaviour of joints to hollow steel sections.
FORTRAN — should this be the engineer's computer language?
Authors: Mufti A. A. , Jaeger L. G.
Published: January 2010

The authors consider the advantages and disadvantages of FORTRAN as the usual computer language for engineers, by comparison with such other possibilities as PASCAL, APL, PL/1, and ALGOL. The comparisons are based upon several distinguishing parameters, among which are stability of the language over a relatively long time-span, evolution towards a more structured form, existing investment in software for engineering applications, and the question of whether the language is of the compiler or interpreter type in normal usage.The evolution of FORTRAN to the present (FORTRAN 77) is traced and future developments are indicated. The case is made that FORTRAN and APL are not directly comparable with one another, since one is of the compiler family whilst the other is an interpreter type. It is argued that APL cannot be the language for large-scale engineering programs because of its interpreter nature.Comparison between FORTRAN and other compiler languages is also made directly. The conclusion reached is that FORTRAN has proved itself capable of being stable over long periods, of being well suited to engineering because of its intermediate level of mathematical sophistication, of being capable of steady improvement towards a more structured condition and of being the vehicle for a massive investment in software. It is therefore recommended that FORTRAN continue to be the principal computer language of engineers. Keywords: programming languages, application software, compiler, interpreter, character set, stability, evolution.
Nonlinear analysis of concrete structures
Authors: Ghoneim Ghoneim A. M. , Ghali Amin
Published: January 2010

A computer program is developed to determine the response of reinforced and prestressed concrete structures subjected to monotonic or cycling loading. The nonlinear stress–strain relationship of concrete and steel is accounted for by applying the load in increments and performing a series of iterations. The structure is treated as an assemblage of thin plate elements subjected to in-plane forces and bending. In the calculation of the structure stiffness, each element is assumed to be composed of a number of layers and the stiffness is allowed to vary over the area of the element and from one layer to the other according to the associated stress.The program employs an efficient finite element that makes it possible to use a relatively small number of elements. The reinforcements are idealized either by smearing a mesh or bars into a steel layer or, with heavy concentrated reinforcement or a prestress tendon, each reinforcing element is accounted for separately.The efficiency of the proposed model is tested by applying the computer program to three structures employing a very small number of elements in their idealization. The finite element idealizations are shown and the results of the analyses are compared with published experimental work.
Duration of load effects in lumber. Part I: A fracture mechanics approach
Authors: Johns Kenneth , Madsen Borg
Published: January 2010

In Part I of this paper, the deterioration of the strength of lumber with continued application of constant stress, called the duration-of-load effect, is treated using a viscoelastic, limited ductility fracture mechanics model. The model is explained and developed in a general way, then modified for use with commercial lumber. The problems of assigning correct creep function parameters and values of stress ratio for use in calculations involving the model are discussed. The evident weakening of boards surviving a long-term test can be used to project a failure time that is longer than the test period. Numerical results are shown and compared with the Madison curve, the basis for current design codes. Parts II and III of this paper demonstrate experimental verification and discuss design implications.
Duration of load effects in lumber. Part III: Code considerations
Authors: Madsen Borg , Johns Kenneth
Published: January 2010

The implications for practical structural design with wood of a visco-elastic fracture mechanics model, recently developed and verified experimentally by the authors, are presented. These are compared with those of the presently used Madison concept, and with those of the cumulative damage models. Following discussion of present practice and the consequences of the fracture mechanics model, specific design recommendations are made as to how this more complicated model might be incorporated into design codes.
Recommended moisture adjustment factors for lumber stresses
Authors: Madsen Borg
Published: January 2010

The present allowable stresses for lumber and the associated adjustment factors stated in Canadian Standard CSA-086 are based upon tests conducted using small clear wood specimens. Recent comprehensive tests in which full-size lumber specimens were used (in-grade testing) showed that the present allowable stresses cannot be confirmed and also that new adjustment factors need to be developed.This paper deals with the effect of moisture content on the strength properties. Tests were conducted and reported dealing with: bending, stiffness, tension, compression parallel to grain, compression perpendicular to grain, and shear. From these tests it was possible to make specific recommendations for a new set of moisture content adjustment factors, to be used in design, that more realistically reflect the behaviour of lumber.
Compact formulation of pipe network problems
Authors: Smith Alan A.
Published: January 2010

Solution of problems in water distribution networks usually proceeds in one of two ways: (1) analysis of flows in the links, or (2) analysis of the head at the nodes. In the former case, which is somewhat commoner and has certain computational advantages, the user is usually required to generate input data by defining the set of independent loops in the circuited network in addition to the usual node and link characteristics. Such methods are acceptable for analysis where the topology of the network remains constant. A method is presented here that allows the node and loop equations to be generated automatically from a very simple data file defining nodal stipulations and link characteristics. The equations are reduced to a small set of simultaneous equations involving only the nonbasic or redundant variables. This greatly reduces the memory requirements and also speeds solution of the equations. Either an iterative linear approximation or the Newton–Raphson method may be used to solve the simultaneous equations. The approach is useful in design and optimization studies since it allows links to be deleted and/or restored with automatic generation of the necessary equations. The method may also be used with microcomputers or even pocket computers since the order of the system of equations to be solved is reduced to the number of loops in the system.
The essence of mathematical models of reservoir storage
Authors: Klemeš V.
Published: January 2010

It is argued that the essence of all reservoir storage models, whether deterministic or stochastic, is the continuity and dynamic equations, both in a very simplified form. The proliferation of storage models is traced to unrecognized redundancies arising as a consequence of language barriers, specialized jargons, and limited knowledge and understanding of published work. Examples of some redundancies are shown in detail and the effective identity of models involving reservoir routing, rule-curve regulation, and any type of operation policy is demonstrated.
Atrium on Bay: The optimum use of reinforced concrete—concrete technology aspects
Authors: Ast P. F. , Bickley J. A.
Published: January 2010

The Atrium on Bay is a retail and office complex of about 130 000 m2 built in downtown Toronto. Two advanced concrete technology concepts were used on the project.For the columns, the age at which the specified compressive strength was required was specified at 90 days instead of 28 days. In addition, the incorporation of a pozzolanic material was specified for the concrete. Column sizes and the amount of reinforcement were based on the 90-day strength, thus reducing their size and the amount of reinforcement required. This also significantly reduced the cost of the concrete.For the concrete slabs, accelerated construction was achieved by the use of a mix with good early strength gain and by a pullout testing system to confirm early strength. The same testing system was used to check in-place strength at later ages. Keywords: column design, column cost, 90-day strength, pozzolanic, pullout testing, in-place strength, accelerated programme, fly-ash.
Transport of pollutants in natural streams
Authors: McCorquodale J. A. , Imam E. H. , Bewtra J. K. , Hamdy Y. S. , Kinkead J. K.
Published: January 2010

A modified two-dimensional mathematical model has been developed to simulate the dispersion of soluble degradable and nondegradable pollutants discharged from multiple industrial outfalls along a large river. This model takes into account the effects of depth and velocity variations in both longitudinal and lateral directions, the removal rates of degradable organic trace pollutants, the lateral convection of mass, and the effect of jet mixing and dilution at the outfalls. It can also accommodate the rapid convergence or divergence in stream width and the influence of an island and of flow diversion on pollutant dispersion.The model was validated by using phenol as a pollutant and comparing the computed values with the field data collected by the Ontario Ministry of the Environment. The application of this model to the simulation of organic pollutant levels in the St. Clair River due to discharges from multiple sources is demonstrated in this paper. Keywords: degradable pollutants, dispersion; jet mixing, pollutant transport, multiple outfalls, nondegradable pollutants, St. Clair River.
Nonlinear response and stability of structures
Authors: Ellyin Fernand
Published: January 2010

The trend towards slender and lighter structures has shifted the emphasis in design from strength to stability and deflection criteria. Approximate methods have been suggested in design codes to complement the traditional methods and to compensate for secondary effects.In this paper a procedure is outlined whereby the effects of axial forces are automatically accounted for. The method is first described by formulating the stiffness of an element in its deformed position. It is then shown that any existing computer programme can easily be modified to incorporate the axial force effects on the deformation and overall stability of the system. Numerical examples are provided and shortcomings of the approximate methods are discussed. A computer programme named CALTOP is developed that is capable of predicting results for linear as well as nonlinear behaviour of a given structure. It also indicates the critical (instability) load of the system. Keywords: axial force effects, buckling, building codes, columns, computer programme CALTOP, deformations, displacements, elastic, frames, critical loads, matrix analysis, moments, nonlinear analysis, safety, stability, stiffness matrix, structures.
Concrete placing productivity
Authors: Kieffer Tim K. , Selby Ken A.
Published: January 2010

Extensive field observations have been made on 104 sites where concrete was being placed. A variety of concrete operations and transport equipment was studied. The mean volume being placed each hour and each man-hour has been determined. Variations in productivity have been established throughout the day. The duration and nature of delays in the placing operation have been determined and allocated to three categories: concrete trucks, transport equipment, and manpower.
An experimental study on the uniaxial and biaxial flexural tensile strength of concrete
Authors: Zielinski Zenon A. , Spiropoulos Ioanis
Published: January 2010

The flexural uniaxial and biaxial tensile strength of concrete was studied experimentally on one-way and two-way ribbed slab specimens. The specimens, consisting of a thin slab and deep ribs, constituted part of a waffle-like structure.Uniaxial tension was achieved by supporting the specimens at two points at the ends of one rib, and biaxial tension by supporting the specimens at four points at the ends of two cross ribs. In both support conditions, load was applied in the middle of the slab, thus introducing flexural tension in the ribs and compression in the slab.Measurements of tensile strain were carried out by means of uniaxial strain gauges attached to the bottom surface of the ribs. The modes of failure of concrete in uniaxial and biaxial tension were observed and are discussed in this paper. A revised biaxial failure envelope of concrete in tension is proposed.The test results indicate that the tensile strength of concrete is about 38% higher in the uniaxial stress state than in the biaxial. Keywords: concrete strength, uniaxial and biaxial tensile flexural strength, maximum strains, cracking, ribbed structure, waffle structure.
A two-dimensional numerical model of estuarine circulation using cubic splines
Authors: Wang Pu , Kahawita R.
Published: January 2010

A two-dimensional, laterally integrated, numerical model has been developed to represent the velocity and salinity distribution along an estuary. The governing equations, which express the conservation of mass, momentum, and salt or heat content, are solved by a finite difference method in combination with spline functions.The model has been applied to the estuary of the Great Whale River in the James Bay region and results of the simulation are presented and compared with tide gauge data. The sensitivity of the model to various values of the stratification parameters that influence vertical diffusion has been studied and some preliminary results presented.The use of the cubic spline formulation in computational hydraulics has been found to be promising and warrants further development.
Column behaviour of cold-formed hollow structural steel shapes
Authors: Davison T. A. , Birkemoe P. C.
Published: January 2010

This paper presents a theoretical model describing the column behaviour of cold-formed heat-treated and non-heat-treated hollow structural steel (HSS) shapes. Member cross-sectional parameters in the form of residual stress and yield strength gradients as well as the member initial crookedness are incorporated into the column model. The parameter magnitudes used and their dispositions throughout the model are based on current experimental and theoretical research. The effect and relative importance of these parameters in determining the theoretical column strength is illustrated. The adequacy of the theoretical model in determining HSS column strength is shown by comparing it with the results of experimental tests conducted on full-sized HSS specimens. Finally, design curves for each of the HSS types studied are recommended.
Sediment transport by waves and currents
Authors: Quick Michael C.
Published: January 2010

Sediment transport is measured under the combined action of waves and currents. Measurements are made with currents in the direction of wave advance and with currents opposing the wave motion. Theoretical relationships are considered that predict the wave velocity field and the mass transport velocity for zero current and for steady currents.Following Bagnold's approach, a transport power relationship is developed to predict the sediment transport rate. Making assumptions for the mass transport velocity, the transport power is shown to agree with the measured sediment transport rates. It is particularly noted that the sediment transport direction is mainly determined by the direction of wave movement, even for adverse currents, until the waves start to break. Keywords: sediment transport, waves and currents, coastal engineering.
Dynamic live loads at a rock concert
Authors: Pernica G.
Published: January 2010

Vibration measurements have been taken in a sports arena during a 3 h rock concert to determine the effect of audience response on the dynamic behaviour of a stand area having a fundamental frequency below 5 Hz. The stand area, consisting of precast, prestressed concrete beams, was subjected to intervals of foot stamping and hand clapping at repetition frequencies between 2 and 3 Hz.Amplitudes of the resulting resonant and near-resonant behaviour are presented; dynamic live loads are calculated and together with static live loads are compared with design loads specified in the National Building Code of Canada.
Wastewater treatment plant, process control experiences using a minicomputer
Authors: Monaghan Brian A.
Published: January 2010

Since 1978, the Wastewater Technology Centre has investigated the use of continuous monitoring sensors and real-time computers for automated data acquisition and control of the activated sludge process. The aim of this work is to improve plant performance and reliability through the application of effective process control strategies.This paper highlights our experiences pertaining to: (a) evaluation of online instrumentation; (b) software development for data acquisition and control; and (c) process control strategies investigated. The majority of this study was carried out using two parallel 16.4 m3∙d pilot plants interfaced to an HP 1000 minicomputer. Keywords: Activated sludge, automated process control, wastewater treatment, dissolved oxygen control, online instrumentation, real-time computer, energy saving, minicomputer, step feed aeration.
On the erosion of consolidated clay material by a fluid containing sand
Authors: Kamphuis J. W.
Published: January 2010

Erosion of a consolidated clay material by fluid containing sand was tested in a laboratory facility. Two modes of erosion were distinguished: "sand blasting" or impact of individual sand particles moving by saltation and "milling" by sand particles forming part of a moving bed layer of discontinuous dunes. Sand blasting resulted in the more severe erosion and this process was adjusted during the experiments to yield maximum erosion rates. It was found that the overall bed degradation rate was a result of many local, shallow erosional features which coalesced. The maximum overall rate of bed degradation was found to be of the order of 0.2 mm/h or 1.75 m/year for a clay material consolidated to 345 kPa.
An experimental investigation of double chord HSS trusses
Authors: Korol Robert M. , Mirza Farooque A. , Chiu Ernie T.-C.
Published: January 2010

The results of a series of five large scale experiments on Warren trusses comprised of square HSS and utilizing the concept of a double chord are presented. The trusses were simply supported and loaded at their top chord panel points, thus simulating gravity loading. It was found that the bolted type, the back-to-back with overlap configuration, and the back-to-back with stiffening plate all sustained a loading that caused a member failure. The joints showed little or no duress. On the other hand, the two standard type trusses suffered joint failures principally by chord shearing at the ends of the top chord. This amounted to a reduction in strength of about 20% of the values of the other trusses. In this paper some design details are presented to help alleviate the problem of inadequate end joint strength.
Predicting the behaviour of HSS double chord trusses—a comparison with test results
Authors: Korol Robert M. , Mirza Farooque A. , Chiu Ernie T.-C.
Published: January 2010

Predictions from a previously developed analytical model that takes into account plastic hinging action and includes the effects of axial load and moment interaction are compared with the results of tests on double chord RHS trusses. The model incorporates a shear spring mechanism that is applicable to gap joints of HSS trusses. Load–displacement curves generated by the program are in reasonable agreement with the majority of truss tests. However, calculated moment – axial force interaction curves tend more to predict trends of behaviour rather than to be quantitatively accurate.
Finite element analysis of soil–steel structures
Authors: Hafez Hisham , Abdel-Sayed George
Published: January 2010

The present paper introduces some improvements in the finite element analysis of soil–steel structures. It applies two-noded spring-type interface elements and accounts for the compaction effects during construction simulation. The analyses are performed in increments using a hyperbolic stress–strain relationship for the nonlinear behaviour of the soil and take into account the shear or tension failure in the soil elements. Also, a combination of constant and compatible linear strain elements for soil is used to increase the accuracy of the analysis around the conduit while keeping the storage requirement and computation time for the numerical solution manageable.The analytical results show satisfactory agreement with those obtained experimentally. They also show that the American Association of State Highway and Transportation Officials (AASHTO) provisions overestimate the thrust due to live load and underestimate the thrust due to dead load. A better comparison is found with the Ontario Highway Bridge Design Code (OHBDC).
Eccentrically loaded bolted beam connections
Authors: Wing P. Chung , Harris P. J.
Published: January 2010

For many years, elastic theory has been used in analysing and designing eccentrically loaded riveted and bolted connections. During the past 20 years, tests and studies have led to the development of several new methods, including the use of an effective eccentricity in elastic design, and ultimate strength methods using plastic analysis or the exact load–deformation response of the bolts. In this paper, a design method using a simple elliptical shear–moment interaction formula is proposd. An experimental program was carried out to investigate the behavior of eccentrically loaded bolt beam connections failing in bearing on the beam webs. Failure loads of tested connections are compared with theoretical values from the various analytical methods. It is concluded that the traditional elastic method using actual eccentricities is the most suitable and direct method for the design of any of the bolt configurations considered in this paper. The ultimate strength method using the exact load–deformation response of the bolts is too complex for design office use, except in the form of tabulated values. The elliptical interaction curve or the elastic method is just as accurate and much simpler to apply. Keywords: connections, high strength bolts, beams, structural steel.
A simplified approach to calculating storage pond volumes
Authors: Chua Kenneth L.
Published: January 2010

A simplified approach is presented for determining the pond storage volume required in new subdivisions in order to achieve a desired peak outflow rate.The method utilizes the runoff coefficients in the "rational formula" to arrive at the total volume of runoff. The total discharge volume is determined using a pre-determined peak discharge as the maximum outflow rate. The difference between inflow and outflow volumes yields the storage requirement. To optimize the storage volume, the storage function is maximized. Newton's iteration technique is used to arrive at the optimum parameters. Keywords: simplified approach, storage, volume, pre-development, outflow, optimization, statistical analysis, intensity–duration–frequency curves, runoff control.
Upstream–downstream: Rights and responsibilities
Authors: Waller D. H.
Published: January 2010

A lengthy trial in the Supreme Court of Nova Scotia may influence design of future stormwater systems in Canada. The developer of a 203 ha area sued an upstream developer and the provincial department of transportation, claiming real and anticipated damages from increased flows and volumes of stormwater. The plaintiff claimed that it was entitled to have the defendants reduce quantities and rates of flow, or to have costs of enlarging its system paid by the defendants. The Court concluded that the defendants were not required to restrict flows to pre-development levels as long as they used natural watercourses and did not cause their natural capacity to be exceeded. The paper discusses the implications of these findings and their relationship to requirements of storm drainage design criteria developed by a municipal–provincial drainage task force. Keywords: drainage law, riparian rights, storm drainage criteria, stormwater management.
Load distribution in continuous composite bridges
Authors: Kennedy John B. , Grace N. F.
Published: January 2010

The influence of transverse diaphragms on the load distribution in composite bridges has been minimized in current design codes. Tests have shown that when diaphragms having an I-section are rigidly connected to the longitudinal girders, a rigid gridwork is formed; this gridwork in composite action with the concrete deck distributes the wheel loads on the bridge in an orthotropic manner. In this paper, the influences of the number of diaphragms, aspect ratio, skew, and cracking of the concrete deck on the transverse load distribution in continuous composite bridges are examined. The theoretical results are verified and substantiated by tests on two 1/8-scale bridge models. The results indicate that such diaphragms, rigidly connected to longitudinal girders, significantly enhance the transverse load distribution, and thus a reduction in the design load for the girders results; the degree of this enhancement increases with increase in the width as well as the skew angle of the bridge. Furthermore, transverse cracking of the concrete deck at the intermediate support(s) does not appear to influence significantly the transverse distribution of the design parameters.
A residual noise model for streamflow prediction
Authors: Logan L. A. , Lennox W. C. , Unny T. E.
Published: January 2010

A nonlinear, conceptual hydrologic model is formulated for use in predicting flows under conditions of controlled input. The model has time-invariant parameters and a residual noise model is incorporated for sequential prediction of hourly flows using a closed loop feedback scheme with hypothetically controlled inputs which are adapted to the residuals. The residual model derived comprises error terms which are correlated in time and variable.It is concluded that the residual noise model approach using an input control adjustment algorithm with adaptation to the model residual, produces satisfactory improvement in flow prediction compared with deterministic predictions using physically measured inputs. Keywords: flow prediction, nonlinear model, residual, correlated noise, input control, adjustment, algorithm, adaptation, measurement, satisfactory improvement.
Rapid erection of a concentrate loading facility using precast concrete in a remote location
Authors: Keeler R. D. , Rizkalla S. H.
Published: January 2010

This paper presents the design concept and construction details of a concentration loading facility in northern Manitoba under adverse conditions. The facility was constructed using plant-produced structural components which had to be shipped by rail to the site and assembled using the post-tensioning technique to provide structural integrity.The main elements of the structure were precast footings, precast retaining walls, and precast, prestressed channel-shaped girders. The project described in the paper is an efficient design highlighted by quality control and significant saving in construction time. The concept lends itself to many types of loading and storage facilites for remote locations.
A proposal to improve the static torsional provisions for the National Building Code of Canada
Authors: Tso W. K.
Published: January 2010

A proposal consisting of four recommendations is presented to improve some of the shortcomings of the seismic torsional provisions in the National Building Code of Canada 1980. The first two changes will improve the torsional moment estimates for buildings with small and large ecentricities, taking the effect of modal coupling into account. The second two proposed changes clarify the limitations of the static code provisions.
L'utilisation de matériaux naturels pour la construction du barrage OA-5 sur la rivière Opinaca
Authors: Massiéra Michel , Pelchat Claude
Published: January 2010

The OA-5 Dam is one of the earth structures of the EOL (Eastman–Opinaca–La Grande) project within the 'La Grande' hydro-electric complex at James Bay, Quebec. Three rivers were diverted to the La Grande River to increase the hydro-electrical potential of the LG-2 power plant. Dam OA-5 (32.3 m high and 385.6 m long) has a zoned section with an impervious central core, and rests on bedrock.The paper describes the different construction phases of the dam, i.e., Opinaca River diversion and closure, foundation treatments, earth and rockfill placement, quality control of materials, and the behaviour of the dam during and after filling of the reservoir. Keywords: closure, compaction, construction, dam, diversion, earth and rockfill, glacial till, grain size analysis, gravel, river, sand.
Feasibility of waffle slabs for bridges
Authors: Kennedy John B. , Bakht Baidar
Published: January 2010

Waffle slabs, although extensively used in buildings, are rarely employed in bridges. Part of the reason for this situation is that a waffle slab, forming essentially a two-way load distribution system, is intuitively considered by many bridge engineers to be incompatible with the basically one-way load transferring system of a bridge. However, it is shown that when there are large twisting moments in a bridge, the orthogonal rib system in a waffle slab provides an efficient means of incorporating the required large moments in two orthogonal directions.Results of an analytical feasibility study into the usefulness of waffle slab construction for bridges are summarized in the paper. It is concluded that the waffle slab construction has the potential of being a more economical alternative to solid slab and slab-on-girder bridges. The analytical results are validated by experimental test results. Apart from being economically viable, the waffle slab construction has the advantage of providing excellent access to prestressing cables for both inspection and maintenance purposes.
Soil failure in shallow covers above flexible conduits
Authors: Hafez Hisham , Abdel-Sayed George
Published: January 2010

Field experience has shown that shallow soil covers above large flexible conduits may fail under concentrated live loads. To avoid such failure, an empirical minimum depth of cover of one-sixth of the span of the conduit is required by the design codes, irrespective of the shape of the conduit.The present paper examines the stability of the soil cover using a finite-element analysis in which the soil stresses are calculated in the upper zone of the mesh. Failure in a soil element is determined using Mohr–Coulomb criteria. A stress transfer technique is used to distribute the stresses exceeding the failure limit between neighbouring elements. Failure propagation is detected when the live load reaches a critical limit. Analytical results are in good agreement with laboratory test results.A parametric study shows that the stability of soil cover is governed by height of cover, conduit shape and size, and the eccentricity of the live axle loads. It also shows that the present code requirements are not adequate for horizontal ellipses, and are too conservative for vertical ellipses.
Forecasting demand for the park-and-ride mode and determining the optimal location of stations
Authors: Sargious M. A. , Janarthanan N.
Published: January 2010

This paper deals with a park-and-ride commuting system designed mainly for servicing urban work trips. A methodology is presented to define the demand for a fixed park-and-ride station location and this procedure is extended for estimating the demand for park-and-ride at any location along a transportation route. A process is suggested for locating one or more stations in such a way that the cost of the system to the commuters and the community is minimized. The models developed in this analysis are applied to a case study area and the results are compared with those derived from the planning models of other researchers.
Mixing efficiency as estimated by nonlinear least squares
Authors: Chapman David T.
Published: January 2010

The suitability of a statistical technique known as nonlinear least squares for use in estimating mixing coefficients was evaluated by fitting models to residence time distribution curves. The washout curves were generated by adding slug inputs of tracers to three different reactors. Each of the reactors, used to treat wastewaters, was a different size and represented a different degree of mixing.Three models, described in the paper, were examined for use in conjuction with the nonlinear least squares technique. They included the axial dispersion, N-tanks-in-series, and Cholette–Cloutier models. The form of the equation for the axial dispersion model depends on the boundary conditions for the reactor being studied. For reactors which cannot be classified as "open" vessels, the required analytical solutions either do not exist or are not suitable for use with the nonlinear least squares technique.Mixing coefficients for the N-tanks and Chollette–Cloutier models were obtained from the tracer washout curves for the three reactors. The residual sum of squares based on nonlinear least squares estimates for the model parameters was compared with the sum of squares obtained using more conventional methods for estimating the parameters. The existence of trailing tails on the tracer curves resulted in misleading parameter estimates for the two models using conventional techniques. Keywords: mixing, least squares, tracer, dispersion, short-circuiting, deadspace.
Collapse by ponding of pneumatic elastic spherical caps under distributed loads
Authors: Ahmadi G. , Glockner P. G.
Published: January 2010

The problem of collapse by ponding of air-supported elastic spherical caps subjected to a distributed axisymmetric central load is investigated. Cases of uniform and nonuniform load intensity are considered and the expressions for the critical intensities for the onset of collapse are derived. Numerical solutions are obtained for a range of values of the parameters and the results are presented in graphical form. The interpretation of the results in terms of some initial depressions filled with a ponding fluid is also discussed.
Concrete crib structures
Authors: Yan H. T.
Published: January 2010

The Slipway Launch Method for concrete crib construction pioneered in Canada is established on a firm engineering basis with the help of time-sequence dynamic analysis developed by the author. The time-sequence diagrams enable the launch paths of the crib to be traced position by position. The linear and angular velocities, as well as accelerations computed for each position, enable the interacting forces between the moving crib and the supporting launch structures to be evaluated. Also, the degree of dip of the front end can be evaluated and, if necessary, the launch height can be adjusted. If a submarine launch is adopted, the dynamic analysis will indicate the maximum hydrostatic pressure for which the water-resistant timber deck has to be designed. It will also indicate whether there is a danger of the crib cartwheeling as it leaves the launchway.After launching, the critical rate of build-up by slip-forming in order to avoid overstressing of the green concrete is evaluated. The floating stability during build-up by alternately ballasting with water and adding wall concrete is checked stage by stage. Finally, design for the permanent conditions using Janssen pressures for bin-action of the fill-material in the crib-pockets is presented. Keywords: concrete cribs, launching, dynamic analysis, time-sequence, submarine launch, slip-forming, floating stability, bin-action.
Elongated columns and column offsets in reinforced concrete building frames
Authors: Hartley Gilbert A. , El Kafrawy Moustafa F.
Published: January 2010

A finite element bending model of a single floor of a flat slab building structure is used here to investigate the effect of column elongations and column offsets on bending moments and punching shears in slab panels. The results are compared with calculations based on current code procedures. The authors conclude that the existing slab model, with artificial end enlargements, could be an effective means of simulating the effect of column elongation and column offset, but that the current expression for the calculation of enlargement moment of inertia is inappropriate, since it does not follow observed trends in behaviour. A modified version of the end enlargement moment of inertia is suggested.
Dynamic response of buildings to ground rotational motion
Authors: Awad A. M. , Humar J. L.
Published: January 2010

Torsional motion in a building subjected to earthquake force is often attributed to an eccentricity between the centres of mass and resistance of the building. However, a more direct cause of torsional response is the presence of a rotational component in the earthquake motion. The effect of such a rotational motion on the response of both a symmetric and an unsymmetric single storey building model is studied. It is shown that the rotational component of excitation may have a very significant effect on the response, and that this effect may at times be more pronounced than the effect of torsion resulting from translational motion combined with plan eccentricity.