摘要:

A series of notched static tension tests was carried out over a range of temperatures to study the influence on the fracture behaviour of a medium strength steel of such parameters as the width of the specimen, the depth of the notch, the thickness of the specimen, the notch location, the root radius of the notch, and residual stresses. Based on these tests, the concept of strength interaction surfaces has been developed. The major portion of such a surface, called the strength cirque, determined empirically, was found to be dependent on the temperature, notch depth, and specimen width and thickness. Strain rate and residual stresses are also expected to affect this surface.From the strength interaction surfaces, the critical flaw size can be estimated as a function of such parameters as temperatue, member width, and thickness, to satisfy the criterion that, at the lowest operating temperature, general yielding of the member at an unflawed section should occur prior to fracture across the flawed section in series with it. Thus a procedure is proposed to prevent the fracture in service of medium strength structural steel (up to 350 MPa yield strength) members containing flaws and subject to low ambient temperatures (down to −60 °C).

ISSN:0315-1468    

DOI:10.1139/l81-038

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The main purposes of modelling are a reasonable understanding of the physical processes involved and a careful evaluation of reasonable alternative designs. The central concern is credibility.Inreasingly, government and municipal engineers involved in urban drainage design supervise studies in which sophisticated computer models are being used by specialists. Because of the large variety of programs available for modelling, the rapid evolution of the models, and because of their complex structures, the studies are becoming increasingly difficult to manage.In the initial study terms of reference, the following component study activities could be specified in detail when bids are requested: problem review, study objectives, performance criteria, requisite accuracy, review of available programs, available data and study resources, program selection criteria, model verification, model calibration, model validation, minimum level of discretization, sensitivity analysis, data preparation and output interpretation, documentation of the modifed program actually used, and preparation of machine readable input and output files for archiving. Many of these activities will be carried out by a reputable engineer in any case.By including these terms of reference, all consultants bidding will be assured that their costs will be met, and clients will be insuring their investment in design engineering with a modest premium. Each of these points is discussed using examples appropriate to stormwater management modelling studies. However, a number of the concepts can be applied generally to other disciplines using computer-based modelling.

ISSN:0315-1468    

DOI:10.1139/l81-039

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The performance of headed shear stud connectors which attach the reinforced concrete slab to the supporting structural steel stubs in a stub-girder structural floor system was examined by testing 28 portions or subassemblages of a complete stub-girder. The major difference which affected the performance of the shear connectors in a stub-girder floor system as compared with conventional composite construction was the increasèd tension which must be carried by critically located shear connectors. One cause of the increase in tension was the secondary bending which resulted from the transverse (beam) shear acting on the concrete slab along the open panel of the stub-girder between interior structural steel stubs. This behavior is similar to the bending which takes place in the chords of a Vierendeel truss.A significant reduction in the shear strength of the connectors resulted from the induced tension. However, the shear strength could be predicted using current Canadian code strengths if allowance was made for the tension in the connectors. The analysis suggested that the resultant of the full applied shear force and 75% of the applied tension force was comparable with the shear connector strength given in the code.

ISSN:0315-1468    

DOI:10.1139/l81-040

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The paper presents an overview of the Ontario Highway Bridge Design Code provisions dealing with the design of soil–steel structures, which are composed of shells of corrugated steel plate, embedded in an envelope of engineered soil. In particular, the paper deals with the engineering aspect of the soil component of the structure. The soil–structure interaction is discussed in the context of arching of dead loads and the influence of soil properties on the ability of the metallic shell to sustain loads. Hydraulic, geotechnical, and other aspects of soil–steel structure design, such as durability and construction, are also briefly discussed.

ISSN:0315-1468    

DOI:10.1139/l81-041

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The paper presents provisions of the Ontario Bridge Design Code for the structural design of the metallic shell of soil–steel structures, and also discusses the development background of these provisions. A simplified method of determining live load effects in the metallic shell is presented. The method is based on results of a well-tested plane strain finite element program. An empirical method for determining live load effects, which is based on tests of full-size structures, is also given. A worked example is given to illustrate the usage of the design provisions.

ISSN:0315-1468    

DOI:10.1139/l81-042

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Results are presented of a laboratory study on the effect of the introduction of a floating cover at the surface of a channel on the mean flow velocity distribution in the then “closed conduit” flow, and on the bed friction factor. It is pointed out that, contrary to common assumption, the location of the maximum velocity is not a point of zero shear stress when the bed and the cover have different roughness characteristics. Semi-empirical and graphical relationships between bed and cover friction factors, relative location of maximum velocity, and bed and cover roughness sizes are presented which are sufficient to estimate the mean flow characteristics below the cover for a given flow discharge and flow depth below the cover. The results may be of importance in the calculation of the characteristics of river ice jams in their initial stage of formation when their roughness is significantly greater than that of the river bed.

ISSN:0315-1468    

DOI:10.1139/l81-043

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

The problem of backwater curve computations under ice covers is very complex. On top of the difficulties which are inherent to computation of backwater curves under open water flow conditions, the ice cover has to be taken into account; its thickness and roughness is time dependent because of variable flow and weather conditions. One of the major factors is the formation of hanging ice dams, especially in most northerly rivers.In this paper we present a complete method for the computation of backwater curves, based on mechanisms of ice formation: the law of equilibrium of the frontal edge, the accumulation of ice under this edge, thermal growth, and finally the equilibrium of hanging dams. The method is based upon measurements taken in the La Grande River.

ISSN:0315-1468    

DOI:10.1139/l81-044

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

In response to the increase in world demand for uranium, mines in the Elliot Lake area of Northern Ontario are being reopened. As part of the rehabilitation program, James F. MacLaren Ltd. was commissioned to undertake studies related to the safe disposal of the radioactive tailings which result from the mining–milling process.Tailings disposal is usually achieved by discharging the tailings slurry and waste rock to an isolated impoundment area. Process water from the slurry and natural runoff from the tailings basin and its drainage area collect at the lowest end of the tailings area. This water must be treated to meet water quality standards set by regulatory agencies. However, no firm criteria (at least for Ontario) for the frequency with which spillage of untreated water might be permitted were discovered. Equally, no criteria regarding the design of an emergency spillway for this type of impoundment were found. In view of this, criteria were developed during these studies using engineering judgement.The evolution of these criteria is discussed in this paper. The hydrologic methods used in the analysis of both long term water level variations and the response to severe storm events are outlined. An example of the application of the criteria for the Elliot Lake area is presented. A method of reducing the cost of meeting these criteria is also discussed. Finally, the need for further independent research on the problem is pointed out.

ISSN:0315-1468    

DOI:10.1139/l81-045

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

A procedure to find the optimum proportioning of laterally unsupported homogeneous I-beams following the limit state design method of CSA S16.1-1974 specification is presented. Both bending moment and shear force is considered in the optimization procedure. The web is unstiffened and the proportioning is restricted to Class 1, 2, and 3 type sections. Some design charts covering a large range of values of unsupported lengths of compression flange and design moments are provided.

ISSN:0315-1468    

DOI:10.1139/l81-046

出版商:NRC Research Press    

年代:1981

数据来源: NRC

摘要:

Load distribution characteristics of cellular structures are greatly influenced by transverse cell distortion and because of this these structures require a somewhat different analysis than those used for other common types of bridges.This paper summarizes the results of an extensive literature search and initial review of the current methods of analyzing cellular and voided slab bridges. The various methods of calculating the equivalent plate parameters, which are necessary for two-dimensional analysis, are also reviewed.

ISSN:0315-1468    

DOI:10.1139/l81-047

出版商:NRC Research Press    

年代:1981

数据来源: NRC