摘要:

Analysis of the potential impact of development alternatives is becoming very complex with the increasing number of constraints, many of them environmental, being imposed. As well, restricted planning budgets require that a rapid identification be made of the most promising alternatives to avoid unnecessary expenditures. A screening model to quickly isolate the most promising alternatives is thus becoming of considerable importance.A computer model that satisfies these concerns in applications involving a series of reservoirs is described in the paper. The model, with both hydrologic and water quality components, simulates and thereby indicates probable changes in downstream flows, reservoir surface fluctuations, and temperature and dissolved oxygen changes in the reservoirs and streams. Through easily adjusted operating policies, reservoir sizes, etc., the model can rapidly determine the potential impact of alternative possible developments. This information is then available to biologists, wildlife, forestry, and social disciplines as an aid in their determination of the environmental impact assessments.A case study application of the model that reflects eastern Canadian conditions is described.

ISSN:0315-1468    

DOI:10.1139/l77-001

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This paper reports the results of an explorative study on the possibility of using a multinomial logit model to replicate and predict multimodal choice for work trips in a Canadian urban context. Modal choice data from Toronto, where a multimode choice situation exists in the line-haul portion of the work trip, are used to develop the model.Both socioeconomic and system variables are used in developing the model and the parameters are estimated using maximum likelihood technique. The developed model is evaluated in terms of statistical criteria and reasonableness tests. It is further examined for its predictive ability by making choice predictions of the sample used in developing the model in addition to comparing the results with the published ones in this area. The overall modeling strategy to be used while developing and testing multimodal choice models has also been illustrated.The study shows that disaggregate models can provide reasonable results when used in forecasting the modal choice between various modes.

ISSN:0315-1468    

DOI:10.1139/l77-002

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The bridge is a three-span continuous steel plate girder structure with a concrete deck slab that is longitudinally prestressed for full composite action. It was selected as a development bridge to incorporate a number of recent research findings and new design techniques.The design live loading was modelled on the observed truck loadings in Ontario, and a grid analysis and a new load factor method were employed for design. The usual specification deflection and impact values were abandoned in favour of a dynamic analysis, resulting in the selection of a very flexible structure with a low natural frequency. Other features include the use of high strength bolts as shear connectors and of slab test panels designed for membrane action with greatly reduced reinforcing steel.The paper describes the initial research, the design features and procedures, the instrumentation of the bridge, and the test programme using two load test vehicles each of which could be loaded to 200 kips (90.72 t). The testing and results are reviewed, and the significant findings are related to the design assumptions and the earlier research. Initial evaluation of the test data indicates that the dynamic testing results and the slab testing results in particular promise to have considerable effect on future designs.

ISSN:0315-1468    

DOI:10.1139/l77-003

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

Maximum upsurges and downsurges in simple surge tanks, resulting from linear decrease or increase in turbine discharge, gate opening, or power output are calculated in turn for simple surge tanks. Tunnel friction and velocity head are considered. The results are plotted in non-dimensional form against conduit friction and the time of closure or opening. In general, both friction and the time of closure or opening reduce the upsurge and downsurge substantially.

ISSN:0315-1468    

DOI:10.1139/l77-004

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This paper is concerned with a major intercepting sewer currently being tunnelled between 50 and 100 ft (15 and 30 m) below the streets of mid Metropolitan Toronto. The sewer is 43 210 ft (13.17 km) long, varies from 5–10 ft (1.5–3.0 m) in diameter and will serve an area of 9466 acres (3834 ha). Flows in the sewer will be remotely controlled by sluice gates and level sensing devices. Vortex structures are used to transfer flow from street level to the tunnelled sewer. The paper describes the conception, design, and construction of the interceptor system.

ISSN:0315-1468    

DOI:10.1139/l77-005

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

This paper is concerned with the analysis of simply supported concrete bridges composed of main girders, having cross sections in the form of a T or an I, interconnected by cross girders. A simple empirical formula is presented for the distribution of wheel loads between the main girders. The formula is based on the computer analysis of a wide range of bridges idealized as a grid. The empirical formula and the computer results show good correlation.The formula presented is intended for use in bridge design and is suggested to replace equations in current American and Canadian specifications for highway bridges (AASHTO 1973 and CSA S6-1974), which lead in most cases to overly conservative designs.

ISSN:0315-1468    

DOI:10.1139/l77-006

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

A study of urban water consumption in the prairie cities is being undertaken to determine what effect metering or pricing policies can have on summer and winter consumption, and eventually on the long run benefits and costs of supply. Of particular interest is the comparison of consumption patterns in Calgary and Edmonton, the two 'twin' cities of Alberta. These two cities are very similar in size, industrial–residential mix, and climate, but Calgary uses more than twice as much water in the residential sector, where over 80% of the customers are unmetered. Initial analysis of the data indicates that the increased consumption is due mainly to the difference in pricing policies used by the two cities.

ISSN:0315-1468    

DOI:10.1139/l77-007

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

In recent years there has been a rapid expansion in the number of structural analysis and design computer programs commercially available to the design engineer. The following paper summarizes the current 'state of the art' of this software and outlines some of the major features. A broad coverage of the practical considerations surrounding the use of these programs is followed by a description of individual programs and their uses. Only those programs known to be readily available through Canadian computer bureaus are included in the review.

ISSN:0315-1468    

DOI:10.1139/l77-008

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The shear strength of dimension lumber is studied considering both the case of straight-grained, clear material and that where the strength is controlled by the rapid propagation of an existing crack such as an end split. Shear strength in the case of clear material is studied by using a size effect model based on a weakest link approach to fracture. In the case of end splits, the strength of the member is studied by using concepts of linear elastic fracture mechanics. Methods are given for developing allowable stresses in both cases. Considering uniformly distributed loads on which current span tables for design are based, maximum tolerated lengths for end splits are derived.

ISSN:0315-1468    

DOI:10.1139/l77-009

出版商:NRC Research Press    

年代:1977

数据来源: NRC

摘要:

The components of a comprehensive model study involving both meteorological and wind tunnel investigations are discussed. An application of the procedures is illustrated by a case study involving a building of intermediate height and unusual geometry. The effectiveness of the wind tunnel study is presented in terms of comparisons of the resulting predicted loads with those derived from building codes, and in terms of the improved knowledge of wind action available to the designer.

ISSN:0315-1468    

DOI:10.1139/l77-010

出版商:NRC Research Press    

年代:1977

数据来源: NRC