摘要:

Highway location is one of the basic but more complex problems in highway development. It is ill-structured by nature, involving the assessment of a variety of impacts, some of which are very difficult to quantify. Furthermore, the data available are often uncertain, especially in the early stages of the project.This paper outlines the use of Prolog for a prototype of a highway location assistant system. The main issues addressed are the way in which uncertain information is handled, the flexibility of the structures used to represent spatial data, and how conventional evaluation procedures can be combined with heuristic principles to solve the problem. Expert-system-like explanation facilities are also present. These facilities are useful to document the decision process and as a training tool for novice engineers, and they can also help in debugging and improving the system.Key words: highway route location, knowledge-based system, fuzzy numbers, Prolog programming.

ISSN:0315-1468    

DOI:10.1139/l88-099

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

A study was conducted to assess the applicability of the Soil Conservation Service (SCS) equations for runoff prediction in the Ottawa – St. Lawrence lowlands. The equations were developed under climatic, soil, and topographic conditions very much different from this region. An analysis of 13 runoff events showed that time of concentration was underpredicted by empirical formulae and the upland method. There was also considerable variation between measured and predicted lag times and times of peak flow. Rainfall intensity was found to influence both time of concentration and lag time. Using antecedent moisture conditions (AMC) level 2, the SCS triangular hydrograph model generally underpredicted both runoff volume and peak flow. However, increasing the curve number to reflect AMC 3 resulted in improper synthesis of the flood hydrograph and gross overprediction of peak flow. From these results, it is evident that new criteria for antecedent moisture conditions and hydrologic soil groups must be derived for the Ottawa – St. Lawrence lowlands. Seasonal curve numbers should also be developed.Key words: hydrology, rainfall, runoff, peak flows, SCS model.

ISSN:0315-1468    

DOI:10.1139/l88-100

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Porous dikes have been proposed for use in blocking access of fish to cooling water intakes in power plants using large cooling ponds for heat dissipation. Flow through such dikes is neither of the Darcy type nor quadratic, the friction factor depending on both the Reynolds number and material properties. Full-scale tests of the dike material proposed for the LaSalle County power plant confirmed the material-property and Reynolds-number dependencies reported in the literature and permitted calibration of the head-loss parameters for the prototype material under two placement configurations. Limited tests on dike clogging by surface debris permitted quantification of the additional head loss which clogging could cause.Key words: porous media, cooling ponds, dikes, scale model tests.

ISSN:0315-1468    

DOI:10.1139/l88-101

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Two similar mixes were made with cement contents of about 350 kg/m3and a water–cement ratio of 0.50. The concrete specimens, moist cured for 7 days, were cured in air for 28 and 120 days, respectively, prior to heating. The exposure temperatures were 75, 150, 300, and 450 °C. The periods of exposure at each temperature were 2, 30, and 120 days.The compressive strengths, before heating, of the specimens cured for 35 and 120 days were 41.0 and 46.2 MPa, respectively, and the flexural strengths were 4.9 and 5.8 MPa. Compared with those strengths, the strengths of the specimens heated for 30 days or more increased at 75 °C but decreased at higher temperatures. The losses increased with increase in temperature, reaching about 30% at 450 °C.The flexural strength of the concrete cured in air for 28 days was more adversely affected than was the compressive strength. The flexural and compressive strengths of the concrete cured in air for 120 days were affected to about the same degree. The longer curing period had little effect on the relative losses in compressive strength, but the longer curing period reduced the loss in flexural strength. In most applications, the loss in strength could be compensated by proportioning the mix to overdesign for strength.Key words: high-density concrete, ilmenite, aggregates, high temperature, mechanical properties, nondestructive tests.

ISSN:0315-1468    

DOI:10.1139/l88-102

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

When the Revelstoke Project reservoir was filled to elevation 560 m in March of 1984, 13 m below its normal operating level, a vertical transverse crack opened in the face of the concrete dam allowing as much as 15 000 L/min (0.25 m3/s) of water to leak into the drainage gallery. Within 2 weeks remedial measures had closed the crack and stopped the leakage. Two months later the powerplant came into service and all other features of the project performed as expected. This project, with its 2700 MW powerplant and 175 m high concrete gravity dam, is one of the largest in North America. It was planned, designed, and its construction administered by BC Hydro. This paper briefly describes the project features, planning decisions, design, and construction of the $2 billion project.Key words: hydroelectric, dam, powerplant, spillway, planning, design, construction.

ISSN:0315-1468    

DOI:10.1139/l88-103

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

CAPDET is a computer-assisted procedure for the design and evaluation of wastewater treatment facilities developed by the U.S. Army Corps of Engineers and the U.S. Environmental Protection Agency. The purpose of this study was to develop a procedure for applying CAPDET to the capital cost estimation of Canadian wastewater treatment plants without altering the source code. The proposed methodology is simple and efficient, requiring no additional data to that normally used in CAPDET.A total of 10 Canadian wastewater treatment plants were studied which included many of the treatment processes used in Canada. Six plants were used to develop the procedure while four plants were used to verify the procedure. The design flow for the selected plants ranged between 550 and 13 600 m3/d. Construction cost estimates generated using site-specific design information were compared with those obtained using the default database provided in CAPDET. The importance of the various unit costs on the total plant cost was also determined.Under the proposed methodology, unit costs are first adjusted to the date of construction using appropriate inflation indices. Wall concrete, slab concrete, and excavation costs are increased by an additional 15, 50, and 25%, respectively, to account for differences in construction practice. A final estimate reduction of 15% is performed to account for Canadian conditions.The procedure provides construction cost estimates that are within ± 20% of actual construction costs with a mean absolute error of 11% and an average error of 2.3%. Site-specific design data had little effect on the construction cost estimates with the exception of lagoon treatment facilities. Utilities and support facilities accounted for 20–30% of the cost estimates. The most significant cost parameters were the inflation index values and concrete and building unit costs.Key words: capital cost, construction cost estimation, wastewater treatment plant, mathematical modelling, calibration, verification.

ISSN:0315-1468    

DOI:10.1139/l88-104

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

Using finite elements, the authors studied temperatures and thermal stresses in 1.41 m wide by 2.12 m high sealed double-glazed windows of 6-mm glass with a 12-mm air space between the panes. The purpose was to find factors significantly influencing thermal stresses. Three types of commercially used windows subject to winter conditions (day and night) were analysed: both panes clear glass; outer pane heat absorbing and inner clear; and outer clear with a metallic film on its room-side surface and inner clear. A sensitivity analysis included variations in size of window, gasket and sealant stiffnesses, frame absorption, solar heat flux, exterior air film conductance, and outdoor air temperatures (−5 and −25 °C). Further, the influence of horizontal and vertical shadows was studied. For the calculation of thermal stresses, the authors found that the windows could be analyzed pane by pane rather than as a three-dimensional structure. Solar radiation and particularly shadows had a major influence on thermal stress, while window size and aspect ratio did not. A case study in which the predicted temperatures were compared with those measured by Sasaki in 1974 showed good agreement and indicated that a simpler steady-state rather than transient thermal analysis gave a close estimate of the temperature difference between the centre and edges of panes for design against thermal breakage.Key words: window breakage, thermal stresses, glass temperatures, shadows, double-glazing, finite elements.

ISSN:0315-1468    

DOI:10.1139/l88-105

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

This paper discusses recent developments in the technology of vehicle load and traffic volume data collection and proposes methods for their application. Applications focus on innovative methods for calculating equivalent axle load (EAL) data. The first part of the study contains an example output of the state-of-the-art vehicle monitoring equipment. Typical output of weigh-in-motion scales (WIM), vehicle classifiers, and vehicle monitors are presented to demonstrate the potential of the new technology. In the second part of the study, WIM scale data covering a period of 1 year is analyzed to explore new methods for collecting EAL data. It is shown that, in terms of daily data, EAL repetitions correlate better with the volume of large vehicles (e.g., 5-axle semitrailer trucks) than with the total number of axle counts traditionally collected. Furthermore, the notion of using vehicle length to index broad vehicle classes is explored as a means of obtaining volume counts of the large vehicles. It is concluded that data obtained by vehicle monitors can indeed be used successfully to identify broad vehicle groups.Key words: weigh-in-motion, vehicle classifiers, vehicle monitors, vehicle length.

ISSN:0315-1468    

DOI:10.1139/l88-106

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

It is now well established, strictly speaking, that a grillage composed solely of orthogonal beams can be used for the analysis of slab bridges only when the Poisson's ratio (v) of the slab material is taken to be zero. The effect on the various responses of using a grillage composed solely of orthogonal beams, and ignoringv, is discussed in this paper, and a method is given to account for the effect on transverse moments of making this simplifying assumption. The paper also contains procedures to determine the peak values of the various responses, as well as their integrated values over a given width of the bridge. Using these procedures, it is shown that the spacings of grillage beams in the conceptual grillages used for analysis do not influence the results as much as is generally believed.Key word: grillage analogy, longitudinal moment, Poisson's ratio, slab bridges, transverse moments.

ISSN:0315-1468    

DOI:10.1139/l88-107

出版商:NRC Research Press    

年代:1988

数据来源: NRC

摘要:

The factors that influence the shear–moment interaction of slab–column connections are examined. The Canadian design code, CAN3-A23.3-M84, is evaluated on the basis of its agreement with the observed connection behavior. Other approaches to modelling slab–column connections are examined. It is concluded that, although the code procedure appears to give satisfactory results in practice, it is not based on a rational model of the connection behavior. Of all the alternative methods examined, the truss model provides the best description of the shear–moment interaction behavior of any given connection.Key words: column–slab connections, shear–moment interaction, punching shear, reinforced concrete, analytical models.

ISSN:0315-1468    

DOI:10.1139/l88-108

出版商:NRC Research Press    

年代:1988

数据来源: NRC