bluuebunny/crossref_metadata_2025 huggingface dataset:
Evaluation of tensile bond and shear bond of masonry by means of centrifugal force
Authors: Hatzinikolas M. , Longworth J. , Warwaruk J.
Published: January 2010

A method of evaluating tensile bond and shear bond of masonry structures is presented. A new test procedure based on centrifugal force has been developed and the principles involved are discussed.Results of tests on 30 tensile bond specimens using M, S, and N mortars are reported. Also, results from 20 shear bond specimens are presented.It is concluded that the test apparatus provides an acceptable means of evaluating tensile and shear bond strengths of masonry. The tensile bond of concrete block masonry is of the order of 517, 451, and 343 kPa for types M, S, and N mortars respectively. Shear bond strengths are of the order of 323 and 265 kPa for M and N mortars.
Dynamic tests on a steel-joist concrete-slab floor
Authors: Rainer J. H.
Published: January 2010

Dynamic properties have been determined for a composite steel-joist concrete-slab floor using heel impact and various shaker tests. The three modes located at 7.5, 12.4, and 18.7 Hz exhibited increasing numbers of nodal lines parallel to the joists.Application of vibration annoyance criteria for footsteps indicated that the floor was unsatisfactory. These criteria, presented in CSA Standard S16.1, Appendix G, had been derived specifically for the lowest mode of the floor. Detailed evaluation of the experimental results, however, shows that mode 1 has satisfactory vibration characteristics as a result of its high damping value, whereas mode 2 is identified as unsatisfactory. This is corroborated by subjective assessment. Vibration tests from walking steps were monitored and suitably filtered. Good agreement was found between the annoyance criteria derived from the heel impact test and those for "sustained vibrations" applied to the walking tests.Based on the dynamic properties of the floor, an assessment is made regarding the effectiveness of partitions and truss bracing for reducing footstep vibrations.
Charts for water hammer in pipelines resulting from valve closure
Authors: Ruus Eugen , El-Fitiany Farouk A.
Published: January 2010

Maximum pressure head rises, which result from valve closure according to (a) uniform, (b) equal-percentage, and (c) optimum valve closure arrangements, are calculated and plotted for the valve end and for the midpoint of a simple pipeline. Basic parameters such as the pipeline constant, relative closure time, and pipe wall friction are considered for closures both from partial as well as from full valve openings. The results of this paper can be used to draw the maximum hydraulic grade line along the pipe for these closure arrangements. It is found that the equal-percentage closure arrangement yields consistently less pressure head rise than does the uniform closure arrangement. Further, the optimum closure arrangement yields consistently less head rise than the equal-percentage one. Closures from partial valve openings increase the pressure head rise considerably and must always be considered.
Effect of chemical admixtures on the sulfate requirement of cement
Authors: Ward M. A. , Khalil S. M. , Langan B. W.
Published: January 2010

As the cost of energy and hence the cost of producing Portland cement increase, the question arises as to whether we are obtaining optimum performance from the admixtures we use. As an example, data are presented indicating that a significant improvement in strength and shrinkage can be achieved by optimizing the sulfate content of the cement for given cement–admixture combinations. It is shown that the optimum SO3 is clearly a function of the initial temperature of the concrete, particularly during the first 24 h after casting, a characteristic of considerable importance in hot weather concreting and steam curing of concrete products. It is recommended that more attention be directed towards optimizing the effectiveness of chemical admixtures in both the ready-mixed concrete and precast concrete industries.
Coupling of torsional – translational response of buildings during earthquakes
Authors: Pekau O.A. , Gordon Henry A.
Published: January 2010

Coupling between the torsional and translational responses is introduced in buildings when the centre of mass and centre of resistance are not coincident. The coupling is amplified when the natural frequencies in torsion and translation are close. In this paper an attempt is made to provide guidelines for identifying situations where lateral–torsional amplification can lead to potentially severe earthquake response. The effects of different building plan configurations and arrangements of lateral load-resisting elements are first examined for idealized structures. The results show that buildings with uniformly distributed lateral resistance are especially susceptible to coupling, regardless of the plan configuration. Next, a multistorey frame building is studied for earthquake excitation, with special regard for the effect of closeness of frequencies in the presence of small eccentricity. Here, it is concluded that the common root sum of squares procedure for combining modal responses yields accurate results only when the separation of torsional and translational frequencies exceeds 20% and, also, that the occurrence of lateral–torsional coupling leads to a decrease in total base shear.
Single-angle welded–bolted beam connections
Authors: Lipson Samuel L. , Antonio Manuel E.
Published: January 2010

This paper reports the results of the last phase of an experimental investigation of load tests on full-size single-angle connections in which one leg of the angle is connected to a beam with ASTM A 325 high-strength bolts and the other leg is welded to the supporting member. In the present study, one series of tests has shown that connections with "short slotted" holes are as reliable as similar connections with round holes but provide a greater measure of flexibility. Two other series of connections with round holes, but with different weld patterns, proved to be flexible but could not carry the desired shears.
Nonlinear dynamic analysis of reinforced concrete building structures
Authors: Otani Shunsuke
Published: January 2010

This state-of-the-art paper discusses nonlinear dynamic analysis of reinforced concrete building structures. Nonlinear analysis of a reinforced concrete building is difficult (a) because inelastic deformation is not confined at critical sections, but spreads throughout the structure; and (b) because stiffness of the reinforced concrete is dependent on a strain history.The paper reviews the behaviour of reinforced concrete members and their subassemblies observed during laboratory tests. Then different hysteresis and analytical models of reinforced concrete members are reviewed, and their application to the simulation of building model behaviour is discussed.
Dynamic response of bridge piers to ice forces
Authors: Montgomery C. James , Gerard Robert , Lipsett A. William
Published: January 2010

An analysis of the dynamic response of bridge piers to measured ice loads is presented. The dynamic structural properties of piers and piles are described and the idealization of these structures for purposes of analysis is discussed. The characteristics of ice force histories recorded at a bridge pier in a large river in central Alberta are illustrated and the dynamic response of bridge piers to typical ice force events is determined. The results of this analysis are presented in the form of response spectra, which enable a rapid appraisal of the magnification, or reduction, in response that can result from dynamic effects. The analysis confirms that bridge piers, including massive ones, will fully respond to peak ice forces. Furthermore it shows that, depending on the natural frequency and damping of the pier and foundation, the dynamic response can exceed the static response to the peak ice force.
Treatment of potato-processing waste water by an anaerobic lagoon–filter system
Authors: Lin K. C. , Brown G. J.
Published: January 2010

An anaerobic lagoon–filter system was operated in the laboratory to treat potato-processing waste water at 20 °C and pH 7 under three loading rates varying from 0.149 to 0.719 kg BOD∙m−3 ∙day−1. The overall removals of biochemical oxygen demand (BOD) and suspended solids (SS) were high, in the ranges of 97–98 and 89–97%, respectively. The system was consistently stable in effluent quality despite periods of shock loads and zero input.The optimum loading rates to the lagoon and the filter were 0.3 and 0.4 kg BOD∙m−3∙day−1, respectively. Most of the BOD and SS removals occurred in the bottom portion of the reactors. A base had to be added to the waste water to maintain the pH at 7 for good performance. No lagoon desludging is expected for full-scale operation. Filter clogging is also unlikely under the optimum loading rates.
Computation of natural frequencies of skewed slabs using equivalent rectangular slab concept
Authors: Campbell T. I. , Siu W. H.
Published: January 2010

The natural frequencies of skewed slabs (in the shape of a parallelogram) of uniform thickness and linear elastic isotropic material are considered. It is shown that the natural frequencies of a skewed slab can be related to those of the corresponding rectangular slab by means of an equivalent rectangular slab concept. Charts are presented to allow the computation of the natural frequencies of one-, two-, and three-span symmetric skewed slabs, which are simply supported at each end and free along each edge.
Analysis of capacity requirements for storage reservoirs: a case study
Authors: Muzik Ivan
Published: January 2010

Three procedures of a reservoir storage estimation are considered in analyzing 61 years of historic mean monthly flows on the Red Deer River in Alberta: (1) the required storage capacity is computed from the historic sample; (2) the required storages dependent on the drought duration and severity are computed from the synthetic mass curves of inflow; and (3) the probability distribution of the required storage capacity is estimated from a large number of stochastically generated flow series. Comparison of the three procedures suggests that the stochastic simulation approach may often be the best method in providing reliable information for the design and operation of storage reservoirs.
Evaluation of effective boundary roughness for gravel-bed rivers
Authors: Bray D. I.
Published: January 2010

In some cases the Keulegan equation is utilized to estimate the average velocity for in-bank flows for gravel-bed rivers. To apply the equation, the effective boundary roughness, k5, is usually estimated in terms of some characteristic bed material size.Data from 67 gravel-bed river reaches in Alberta are used to determine an optimum method of defining the effective boundary roughness in the Keulegan equation. The analysis indicates that k5 is best estimated as 6.8d50, 5.2d65, 3.5d84, or 3. Id90. These findings are compared with the work of other investigators who used gravel-bed river data from Britain and the United States.Errors in the estimation of average velocity by the Keulegan equation range from about 20% for D/d90 = 200 to about 100% for D/d50 = 5 if the characteristic bed material size, d0, is used to estimate the effective boundary roughness, k5, rather than the optimum definition of the effective boundary roughness, Cd0, as determined in this note.
Control of oil slicks in flowing water using air bubble barriers
Authors: Lau Y. L. , Engel P.
Published: January 2010

A laboratory investigation was carried out to study the effectiveness of air bubble barriers for the containment and diversion of oil slicks in open-channel flows. It was discovered that air barriers could not detain oil slicks completely but were very successful as diverters. Guidelines for angles of barriers required for diversion and for estimation of oil loss rates were obtained.
Control of aerobic digestion by substrate concentration
Authors: Hamoda M. F. , Ganczarczyk Jerzy
Published: January 2010

Performed laboratory studies on aerobic digestion of activated sludge show that an initial concentration of solids might be effective in reducing digester volume required for sludge stabilization, and lowering the rates of associated nitrification. Therefore, the input solids concentration may be a controlling factor for unwanted nitrogen transformation.The experimental results obtained in the batch and semicontinuous digestion studies indicate similar trends but differ enough to prevent the use of the batch experiment data for the design of continuous flow digesters.
Crack control for reinforced and prestressed concrete structures
Authors: Falkner H. A.
Published: January 2010

The principal relationship between concrete and rebars when cracks form in reinforced concrete (RC) and prestressed concrete (PC) structures is presented. Mainly for better understanding, crack formation in concrete is compared with that of other materials such as wood or soil.Cracks in RC and PC structures are almost unavoidable and are more often caused by restraint forces than by loads. Cracks are harmless for serviceability and durability if crack width is limited to hair cracks up to 0.2 or 0.3 mm. Although it has been proved that cracks up to 0.4 mm wide do not increase corrosion of the embedded steel, engineers have to strive to limit crack width primarily to get a good appearance from concrete structures.References are given to completed RC and PC structures having a maximum crack width of less than 0.2 mm and structures without expansion joints up to a total length of 140 m.
Improved implicit procedure for multichannel surge computations
Authors: Kao Kwan-Hong
Published: January 2010

A procedure for numbering the computation points along a system of waterways is presented for the implicit finite difference solution of open channel unsteady flow problems. In a multichannel system, with each branch watercourse being treated as one-dimensional, application of the proposed numbering procedure will produce a narrow diagonally banded coefficient matrix of simultaneous equations. An existing IBM programme, GELB, can thus be employed to solve the simultaneous equations resulting in a significant reduction both in computer storage requirements and computing time.The tailrace system of Portage Mountain Development on the Peace River, British Columbia, Canada, is a Y-shaped channel to which the proposed procedure was first succesfully applied.
Statical behavior of cropped-web tubular truss joints
Authors: Thiensiripipat N. , Morris G. A. , Pinkney R. B.
Published: January 2010

An experimental and theoretical investigation of the statical behavior of cropped-web joints is reported. The joints have square hollow structural sections as chords and circular hollow structural sections with longitudinally oriented cropped ends as webs. Such joints have the advantage of low fabrication cost compared with that of sawn-or profiled-web joints. Tests of 32 isolated joints with Pratt- or N-truss configurations are reported. The measured strain distributions at the joints are described. Equations obtained using multiple regression analysis to relate the strengths and stiffnesses of the joints to various parameters are presented. The strengths of the joints are found to be acceptable and comparable to those of similar sawn-web joints with small gaps between the webs. The stiffnesses of the joints are also found to be acceptable, provided that the chord walls satisfy certain dimensional criteria.
Longitudinal bending strength of corrugated steel pipe
Authors: Smith C. D.
Published: January 2010

Corrugated steel pipe (CSP) is used in large numbers for drainage structures, particularly in highway engineering. The corrugations increase the wall stiffness of the pipe by a factor of about 100, so relatively light-gauge material can be used to resist the earth loading on the buried pipe. These same corrugations, however, result in a decrease in longitudinal bending strength. This can be an important consideration in situations where the culvert may be undermined at the outlet, or is deliberately cantilevered beyond its imbedment. Strength tests were carried out on three sizes of standard 16 gauge (0.001676 m) rivetted CSP. From this it was determined that the safe cantilever length for a flowing full culvert is about 2 m for pipes of 0.61 m diameter and larger.
New facility to determine fire resistance of columns
Authors: Lie T. T.
Published: January 2010

The new Division of Building Research (DBR) column testing furnace is described and an outline given of the proposed studies that this facility makes possible.
Prestressed latticed beam–columns with offset diagonals
Authors: Ellis John S.
Published: January 2010

A strength increase of 20% was obtained by offsetting the diagonals in prestressed latticed cantilever models loaded at their ends. The purpose of this paper is to describe the research leading up to and including the model tests that provided these strength increases. The paper considers theoretical problems and suggests an outline for further research. At the present time it is important to develop an analytical framework to predict the behaviour of structures that incorporate the concepts of this research.
On the role of uncertainty in the limit states design of steel structures
Authors: Dumonteil P.
Published: January 2010

The study of current work on steel code calibration shows that uncertainties in member resistances, load effects, and structural analysis are most usually assumed to have mean values equal to unity. The risk of failure that would result from the apparent safety index is higher than borne out by experience. Perhaps more important is the fact that it is necessary to assume elastic and determinate properties. These restrictions are removed if the various uncertainties are examined separately. It is then shown that their combined effect leads to a global uncertainty of a random nature, whose mean value is less than 1.0. The actual risk of failure is 5–10 times lower than the apparent one.
Analyse et dimensionnement des bassins d'équilibre par simulation continue
Authors: Patry Gilles G.
Published: January 2010

A new approach to the study of domestic wastewater equalization basins is presented. The proposed methodology is based on the continuous simulation of the process using CSMP/360 (continuous system modeling program) simulation language. Different operating conditions can readily be simulated by the model EQUIL during a single computer run. This feature permits the construction of various response curves from which the volume of the equalization basin can be determined so as to meet the specified effluent variations. Two examples illustrate the use of the model for design purposes.
A design proposal for timber pile supported sewers
Authors: Kelly Harlan G.
Published: January 2010

The design difficulties for rigid sewer pipe and timber pile supports in low-strength soils are reviewed. A proposal is developed to serve as a rational basis of design for assessing vertical and horizontal loads, pile and pile cap selection, flexural design and strength of the pipe to resist vertical loading, pile fixity, and pile column design. Examples of the calculation procedure are given and conclusions by others based on field testing of flexurally reinforced pipe are presented.
Unbalanced snow distributions for the design of arch-shaped roofs in Canada
Authors: Taylor D. A. , Schriever W. R.
Published: January 2010

This note examines in some detail the design snow loads on simple arches and curved roofs recommended in the 1977 Commentary on Snow Loads of the National Building Code of Canada. Empirical modifications that give more appropriate unbalanced snow loads for large-radius arches and that will alleviate the problems caused by some overconservative aspects of the 1977 design loads are presented. They have been accepted for inclusion in the 1980 commentary.
Field studies on the response of floating ice sheets to moving loads
Authors: Beltaos S.
Published: January 2010

The results of field tests on the response of floating ice sheets to moving loads are presented and discussed. To measure time-dependent deflections under moving loads, a convenient method that does not require reference to a fixed datum is developed. This method is based on integrating the output of a sensitive slope indicator. The data support the available theory in most respects. Deflection under a load moving at constant speed is maximized when the speed is equal to a critical value. The critical speed is essentially a function of ice thickness and water depth. Observed critical speeds for ice thicknesses and water depths in the ranges 0.3−1.4 and 1.8−54.3 m, respectively, are generally 10% higher than predicted values; these ranges include present data and earlier data by others. The data show further that critical deflection and strain can be up to 4.6 and 1.4 times the corresponding static loading values. Discussion of this finding points out that abrupt speed changes should be avoided.
Behavior of tubular steel trusses with cropped webs
Authors: Ghosh Anjan , Morris Glenn
Published: January 2010

The consecutive testing to failure of four test joints in each of two identical 7.3 m span × 1.8 m deep tubular steel trusses with cropped webs is described. The behavior of each of the test joints is discussed and compared to that of similar joints previously tested as isolated specimens. Following large chord-face deformations and bending of the webs in the truss plane, failure occurs by out-of-plane buckling of the compression web at those test joints with slender webs, or by yielding and tearing of the tension web at those with stocky webs. Stiffnesses are in close agreement for corresponding truss and isolated joints. Strengths of the truss joints are from 0–23% lower than those of the isolated joint specimens. Joint deformation contributes less than 5% to truss deflection.
An air transport model for Trinidad and Tobago
Authors: Underwood J. R.
Published: January 2010

Trinidad and Tobago is undergoing substantial economic growth resulting from petroleum revenues, the volume of transportation (including air travel) thus expanding rapidly. It is essential, therefore, to provide estimates of future traffic to allow sensible planning to be undertaken. Previous modelling work in this region has tended to be extrapolative. This paper describes work undertaken to evaluate the underlying causal relationships influencing the volume of air travel to the small (population 1.1 millions) twin-island Caribbean republic and to build a descriptive model. The well-tried method of multiple regression analysis was used. Locally available statistical data were utilized, the analysis revealing that airfare, per capita income, and population were the main influencing factors. Cultural ties between zones were taken into account, postwar migration emerging as a proxy variable to accommodate this. Backward projections were made using the calibrated equation and intuitively reasonable forward projections were derived. The paper contains as examples detailed descriptions of the results relating to four of the links studied as well as a presentation of overall results. The technique appears appropriate both to a rapidly changing economic environment and to small nations (for example, other Caribbean islands) in deriving projections for the design of air transport facilities and the planning of services.
An example of the application of statistical techniques to predict lake level elevations
Authors: Koppula Sivajogi D.
Published: January 2010

A knowledge of future lake levels is helpful in the stormwater management of a lake district with respect to flood control measures, land use measures around the lake, etc. The planning of strategies to achieve management objectives often receives wide attention; however, little or no mention is usually made of prediction of future events, e.g., lake water levels, upon which the strategies are based. These future events are of major importance as they determine the type of objectives and hence the strategies that management will have to develop and follow in the future.In the present study, the available data on monthly lake water levels are examined utilizing two statistical methods, namely, the Box-Jenkins time series analysis and harmonic analysis. The statistical models are then used to predict future lake levels; the predictions are compared with actual observations. It has been found that the predictions made by the Box-Jenkins model are closer to the recorded observations. The results from the two independent methods are combined to yield a composite forecast, which gives results that are slightly better than those given by either of the independent methods.
Analysis of prestressed concrete voided bridge decks using STRUDL II finite element programs
Authors: Cheung Sue K.
Published: January 2010

Post-tensioned continuous voided concrete bridge decks are widely used in the Province of Ontario. These bridge deck designs are generally based on one-dimensional analysis. The longitudinal moments are usually calculated by considering the deck as a wide beam, and the transverse moments in midspan and at the intermediate supports are evaluated by treating those portions of the bridge as a transverse beam and a frame respectively.To examine more precisely this two-dimensional structural behavior under various loading conditions, the recently designed Highway 403 underpass at Winston Churchill Boulevard in Mississauga, Ontario, was analyzed using the readily available ICES STRUDL-II finite element program.This paper describes the ICES STRUDL-II finite element modelling and analysis procedures, the results obtained, and the comparisons with conventional calculations.
Hydraulic design for the two-stage stilling basin
Authors: Smith C. D. , Klassen M. J.
Published: January 2010

The two-stage stilling basin is a design sometimes used for high head energy dissipating structures. The distinguishing feature of the design is that essentially two hydraulic jumps occur in series in the same structure. The tailwater depth for the first jump is created by a fixed weir. Tailwater for the second jump is due to the natural tailwater available in the downstream channel. Since most of the energy of flow is dissipated in the first jump, the required tailwater depth to produce a jump in the second basin is considerably decreased, with the result that the entire stilling basin floor may be placed at a higher elevation than for a single basin. This can be advantageous in certain situations.In this paper the results of hydraulic model tests for a two-stage stilling basin are reported. The characteristics of the basin first were studied two-dimensionally using a parallel sided flume. A design criterion was established and this was subsequently verified on a three-dimensional model.
Potential eutrophication of the Rideau River by an urban drainage waterway
Authors: Habicht M. H. , Adamowski K. , Middleton A. C.
Published: January 2010

The chemical characterization and algal bioassay were used in order to study the eutrophication potential of an urban drain (Saw Mill Creek) on the Rideau River in Ottawa. Samples were collected during 8 different peak storm flow conditions.Although nutrient concentrations were observed to increase during storm flows, peak flow concentrations for total phosphorus and nitrogen averaged only 0.190 mg/L and 2.5 mg/L respectively. These concentrations of nutrients did not significantly stimulate algal growth at the 5% addition level. However, at the 10 and 20% addition levels, bioassays produced on the average 0.96 and 1.96 mg/L of algal standing biomass (measured as chlorophyll-a) respectively. These values were significantly different (at 95% confidence level) from the average biomass of 0.50 mg/L produced by the Rideau samples. In the analysis, a linear relationship between algal biomass and nutrient addition was assumed.Alum treatment of Saw Mill Creek, simulated by the jar test, was generally unable to reduce the algal growth when compared with that at any of the addition levels. Thus it was concluded that treatment would have no significant effect on algal growth at low flows of Saw Mill Creek.However, a reduction in the volume of storm flow of the Saw Mill Creek could have a significant effect on algal growth in the Rideau River.
Evaluation of areal versus point rainfall with sparse data
Authors: Nguyen Van-Thanh-Van , Rousselle Jean , McPherson M. B.
Published: January 2010

A theoretical methodology is proposed to establish a relationship between the rainfall at a fixed point and the associated mean rainfall over a geographically fixed area. The distribution relation for mean rainfall over a specific area was derived using an exponential distribution function for hourly point rainfall. Values of the areal correction factor were estimated at equal levels of exceedance probability for point and areal mean rainfalls. Contrary to previous indications for a moving point, it was found that the areal correction factor for a fixed point and fixed area was not always equal to or less than unity. Furthermore, the areal correction factor was found to vary with the return period.
Analogous frames for the analysis of tall shear wall structures
Authors: Smith B. Stafford , Girgis A. M. , Abate A.
Published: January 2010

Three types of analogous frames for the stress and deflection analysis of tall shear walls are presented. They are similar to the wide column analogous frame in having horizontal flexurally rigid arms; however, they avoid the coupling of the shear and contraflexural behaviour inherent in the single column of the wide column analogy. The new analogous frames are suitable for the detailed analysis of individual shear walls or of walls connected by beams to other components. In such combined structures a frame model may be more convenient than a mixture of finite elements and frame elements.
Commentary on Clause 12 Existing Bridge Evaluation of CAN3-S6-M78, Supplement No. 1-1980
Authors: Foster Robert L. , Peterson C. William , Buckland Peter G.
Published: January 2010

The publication of the new Clause 12 Existing Bridge Evaluation of CAN3-S6-M78 Design of Highway Bridges marks a radical departure from the conventional format of bridge design codes. For the first time bridges may be evaluated on the basis of reliability or probability of failure. The philosophy of Clause 12, a guide to its use, the derivation of the theory, and a discussion of the various coefficients used in the clause are given.
Sedimentation of zeolite type A in water and waste water
Authors: Carrondo Manuel J. T. , Perry Roger , Lester John N.
Published: January 2010

A series of experiments was conducted to investigate the settling characteristics of zeolite type A, a non-phosphorus detergent builder, in water and waste water. The results obtained from settling column tests in water compared well with predictions made by applying Stokes' law to the particle size distribution curves, despite the nonsphericity of the particles Model sedimentation tank tests were undertaken and the removals at different overflow rates agreed closely with the predictions made from the column tests. Even at low flow rates zeolite type A removal in water was low.The percentage of suspended solids removed in static column tests using raw sewage was marginally reduced from the values obtained when zeolite type A was absent. Zeolite type A was removed to a lesser extent than the other suspended solids, particularly during the initial stages of the settling tests. In activated sludge pilot plant tests zeolite type A removal averaged 88%.Zeolite type A removals higher than 80% are anticipated in waste water treatment works comprising primary settling and secondary treatment by activated sludge; removals greater than 90% are regarded as probable.
Testing of the Manitou bridge to determine its safe load carrying capacity
Authors: Bakht Baidar
Published: January 2010

The anatomy of a test to realistically determine the safe load carrying capacity of a bridge is presented. Analytically the bridge was declared to be unsuitable for carrying unrestricted traffic and yet the test showed that the bridge was capable of safely sustaining normal loads. The test points out the significance of the structure's response to varying temperatures, and shows that the load carrying capacity of the bridge depends substantially on such interaction of the various components as was not intentionally provided for in the original design.The test was helpful not only in determining the safe load carrying capacity of the bridge but was also instrumental in diagnosing the possible source of distress in the bridge deck slab.
Increase of stress in unbonded tendons in prestressed concrete beams and slabs
Authors: Balaguru Perumalsamy N.
Published: January 2010

In the case of prestressed concrete beams with unbonded tendons, in order to design for strength and serviceability, one has to evaluate the effective prestressing force in the tendon, which is beam dependent rather than section dependent, both at ultimate and working loads. The formulae available in the published literature deal only with ultimate load conditions. A simple equation to predict the tendon stress changes for the complete loading range is presented in this paper. The formula was developed using the basic theory of flexure to obtain the equation for the elastic curve, and numerical integration to obtain the curve lengths. Using the computer generated results of the increase in tendon strain for various span lengths, eccentricities, and maximum deflections, a regression equation was developed. This regression equation predicts the increase in tendon strains as a function of the span–eccentricity and eccentricity – maximum deflection ratios. The recently published stress–strain relation which seems to be very accurate is then used to predict the tendon stress. The results are compared with a set of experimental results. The suggested formula is also consistent with some of the available equations for the prediction of the tendon stress at ultimate load.
Rigid-plastic analysis of floating ice sheets under impact loads
Authors: Kennedy John B. , Iyengar K. J.
Published: January 2010

The deformation response of floating ice sheets under high intensity, short duration loads is examined. Using a rigid-plastic theory, together with a Tresca yield criterion, expressions are derived for the total time of response and the final deformed configuration of floating ice sheets. The influence of the magnitude of the impact load and the load-contact radius on the various design quantities such as deflection profile and stress distribution is discussed. Based on the results derived, a design method is presented to find the safe thickness of a floating ice sheet to sustain a given impact load. The method is illustrated with a numerical example.
An approach to the evaluation of stress-corrosion of high strength steels
Authors: Ellyin Fernand , Matta Rafik A.
Published: January 2010

Experiments have been conducted on high strength prestressing and bridge wires (zinc-coated) to assess their susceptibility to stress-corrosion cracking (SCC). The wires were subjected to various stress levels and corrosive environments. Loss of ductility and reduction in the ultimate strength of these materials are determined. A criterion is then proposed to evaluate the susceptibility to stress-corrosion by means of an index based on the observed mechanical properties of the wires. Further experiments were carried out on another high-strength bridge wire to validate the proposed approach.Based on the experimental and field observations, the proposed method could be applied to select the type of wire used in pre- or post-tensioned concrete construction or in other applications to ensure better protection against SCC.
An interactive computer graphics system for structural analysis
Authors: Hooley R. F.
Published: January 2010

This paper describes a system in operation at the University of British Columbia for structural analysis using interactive computer graphics. The three major components of such a system are a central processing unit, some graphics hardware, and software. The central processing unit should allow fast interactive use of the graphics hardware to eliminate long time delays for the designer. The minimum graphics hardware is a storage tube terminal for the display of vectors and diagrams. The addition of a hard copy unit will relieve the designer from the inevitable pressure of an interactive system and provide time to study the results of an analysis. Finally, a tablet provides for fast input and alteration of data, both geometric and numerical. These three pieces of graphics equipment, terminal, tablet, and copy unit, form an efficient input-output system.Software programs are of two varieties. The first will produce a common data bank via the tablet or generators. The second will draw from that bank for a variety of analyses such as linear, elastoplastic, second order, or dynamic. In all cases the analysis programs plot on the screen scale diagrams of axial, shear, moment, and deflection for instant hard copy. This integrated system of hardware and software provides an efficient analysis tool for both students and practising engineers.
Operational performance of an RBC unit in conjunction with a septic tank
Authors: Atwater J. W. , Bradshaw G.
Published: January 2010

A rotating biological contactor (RBC) unit in series with a septic tank for primary solids removal and sludge storage was monitored for 21 months. The results of that monitoring are summarized in this paper. The treatment configuration produced an effluent that met federal guidelines of 20 mg/L for BOD5, and 25 mg/L for suspended solids. When solids were allowed to accumulate in the septic tank beyond 12 months, there was a marked increase in loading of the RBC with a resultant decrease in effluent quality. A linear relationship could be shown between clarified effluent BOD5 and applied BOD5. The data from this monitoring program suggest that surface area requirements of RBC units utilizing septic tanks for primary solids removal are three times those utilizing conventional primary treatment. When high levels of nitrate were in the unit, feed denitrification occurred concurrently with carbonaceous oxidation.
Construction considerations and controls for soil–steel bridge structures
Authors: Mirza C. , Porter W. A.
Published: January 2010

Soil–steel structures is the name given to bridge, culvert, and underpass types of conduit openings designed with corrugated steel pipe plates (SPCSP) and engineered soil around these plates. The maximum span for these structures has approached 16 m in an arch configuration. Their design was rationalized by Canadian research in the 1960s, concurrently with the construction of several hundred units. Recent codification of design requirements has drawn attention to the need for documenting construction practices and other lesser known physical aspects of these structures. This paper is a contribution towards that documentation.
The use of frame action to resist lateral loads in simple construction
Authors: Nixon Don
Published: January 2010

A building frame may be designed to resist gravity loads by using simple construction, and lateral loads, due to either wind or earthquake, by the use of frame action, provided certain limitations are met. One of these, that the connected members must have solid webs, rules out the use of open web steel joists as flexural members in a frame proportioned on this basis. The reason for this exclusion is explained in the light of recent test results.
Comparison of isostatic and hyperstatic penstocks at Santa Isabel, Bolivia
Authors: Gordon J. L. , Bolliger W. , Cary J. S.
Published: January 2010

Construction of the Santa Isabel hydro project in central Bolivia was completed in 1973. The project includes a penstock, with the lower half comprising an unusual hyperstatic design with no expansion joints and anchors at alternate bends. The penstock was designed for a static head of 864 m plus 15% waterhammer. It burst when filled with water on March 16th, 1973 at a head of 735 m. Cause of the failure was attributed to an improper weld at an unsupported bend in the hyperstatic section of the penstock. Construction of a second parallel penstock was completed and commissioned in March 1981. This paper describes the work undertaken to guard against a repetition of the 1973 failure, compares the isostatic design (with expansion joints) of the upper half of the penstock with the hyperstatic design of the lower half of the penstock, outlines design procedures, and describes construction methods used for installation of the second penstock.
Structural integrity of precast panel shear walls
Authors: Pekau O. A.
Published: January 2010

Precast panel shear walls are investigated for conditions simulating progressive collapse. The latter are simulated by assuming ineffective panels at various levels within the structure. The analysis is performed by an efficient finite element substructuring procedure for both static and seismic loadings, and by a simple rigid-cantilever approximation for static loading only. The principal interest concerns the magnitude and distribution of design forces in vertical and transverse ties which, in the finite element analysis, are modelled by discrete connectors along horizontal and vertical joints. For static loading the results evaluate the accuracy of the simple cantilever design procedure, whereas for seismic loading the magnitude and distribution of connector forces resulting from local panel failure are examined. In particular, it is shown that failure of an exterior panel leads to unexpectedly large concentrations of shear force in the vertical joint, something that is not adequately predicted by the simplified cantilever analysis.
Torsional provisions in building codes
Authors: Tso W. K. , Meng V.
Published: January 2010

A study is made of the accuracy of the static code provisions on torsional effects, with special reference to the National Building Code of Canada of 1977. A uniform frame type monosymmetric 12-story building is used as an example. The static story torque is compared with the dynamic torque computed using the response spectrum technique as outlined in Commentary K of the Code. It has been found that for a building with uniform eccentricity, the static code torque estimate is good if the effect of sympathetic coupled torsional–lateral resonance is small. At the sympathetic coupled resonance, the static code torsional provision underestimates the story torque by a factor of approximately two. Also, it is shown that for buildings with large eccentricities, sympathetic resonance is unlikely to occur and the current Code requirement of doubling the computed torque for design is a very conservative requirement.In addition, the eccentricity expression given in the 1980 Code is used to estimate the story torques for eccentrically set-back buildings and its accuracy is checked with a response spectrum technique. It is concluded that for irregular structures, such as eccentrically set-back buildings, a dynamic analysis is the only reliable procedure for the estimation of the torque loading on the building.
H-frame module and panel — a system for rapid construction of multistorey buildings
Authors: Zlelinski Z. A. , Zlelinski C.
Published: January 2010

A description of the design and practical application of a new precast concrete building is presented. The system combines two basic structural components: a modular ribbed panel of size 10 × 20 ft (approximately 3 × 6 m) in plan, and a three-dimensional H-shaped module of up to 10 × 40–45 ft (approximately 3 × 12–15 m) in plan and 8–12 ft (approximately 2.4–4 m) in height.It is designed for speedy erection of multistorey buildings. The main feature of the system is the simplicity of connections. Large-size, H-shaped modules are erected by stockpiling them one on top of another with simple bearing connections located at mid-height of the supporting columns or walls. The spaces between module stockpiles are filled with modular ribbed panels. In some areas panels are omitted, thus open spaces are created to accommodate staircases or elevator shafts where required. The panels are simply supported on continuous edge brackets that are formed along the entire perimeter of the modules.This system was used in the design of a large building complex recently erected in Edmonton, Alberta. It combined a four-storey hotel, eight-storey office tower, and covered courtyard, all situated above a two-storey underground parkade.A description of the building, production of modules and panels, erection, and some details of the connections are discussed in the paper.
Preliminary design of stiffened simply-supported orthotropic concrete bridge decks
Authors: Ng Simon S.F. , Kulkarni G. G. , Cheung M. S.
Published: January 2010

The direct analysis to determine the transverse distribution of moments in stiffened bridge decks using the differential equation approach becomes laborious, especially in the preliminary design process where several trials are often required to determine the relative dimensions of slab and stiffeners for achieving optimum structural efficiency of the deck. The majority of design charts and tables available to the engineer during the preliminary design process assume absolute dimensions of slab, stiffeners, diaphragms, and their spacing, and thus are more suitable for detail design. This study deals with the development of design charts that express governing parameters in dimensionless form, and with the rapid evaluation of rigidity parameters and critical moments. Such design charts and tables are ideal for carrying out several trial sections to find the most economical structural system during the preliminary design process. The theoretical work is supplemented by a limited experimental programme and good agreements are found.
The effect of foam fractionated lignosulphonates on air entrainment in concrete
Authors: Keirstead K. F. , DeKee D. , Kirk D. W. , Pillai S. U.
Published: January 2010

One of the properties of air-entraining admixtures that may influence their efficiency is their surface tension when combined with mixing water. Lignosol SF is a standard air-entraining agent. With the objective of identifying a product with improved qualities, Lignosol SF was fractionated and two of its fractions, respectively with low (foamate) and high (retentate) surface tension properties were investigated as potential air-entraining agents. Measurements were made both of air content in wet concrete mix and of the air-void characteristics of the hardened concrete.The results showed that at low concentrations and water:cement ratios the performance of all the three products above are similar. However, the foamate fraction becomes more effective in entraining air with increases in concentration and water:cement ratio. Further, this foamate resulted in the hardened concrete having bubbles with a smaller mean diameter than those in the retentate. The spacing factors for both these products were within recommended limits. Keywords: admixtures; air-entrainment; air-voids; concrete; freeze-thaw resistance; Lignosol; spacing factor.