摘要:

The advent of computer-controlled electronic freeway surveillance and control systems in the past decade represents a potentially significant new operational tool for traffic engineers in large urban areas. These systems are capable of responding to rapidly changing traffic conditions and in various demonstration projects they have proven useful in maintaining an acceptable level of service for freeway operations, reducing the extent and duration of traffic congestion, minimizing the adverse effects of accidents and other incidents on traffic operations, and reducing accident experience. Surveillance system goals and techniques for achieving these goals are reviewed in this paper with particular emphasis on the problem of managing unexpected capacity-reducing incident situations. Recent research has demonstrated the feasibility of detecting incidents from traffic flow data, which is desirable for surveillance purposes because this information can be used to implement control strategies which attempt in real-time to divert some freeway traffic to alternate routes. Some of the operational problems involved with freeway traffic management are discussed, particularly the generation of false alarms by detection algorithms and driver willingness to be diverted to alternate routes.

ISSN:0315-1468    

DOI:10.1139/l74-013

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

A method is presented that will give a reasonably good estimate of the cost of structural steel in one or two storey office or industrial-type buildings made of beams, columns joists (short-span), bridging, V-pan, and roof deck. The unit times apply to buildings of simple construction with summer-time erection.The method is illustrated with two example problems and the results are compared with estimates found using the Canadian Institute of Steel Construction (CISC) method, which was intended mainly for use with medium-sized high rise buildings. Both estimates are compared to the price quoted by a structural steel fabricator in the Ottawa area. It was found that the CISC method can also be used for estimating cost of low rise buildings, although it does underestimate the cost of steel when the bay sizes are small.

ISSN:0315-1468    

DOI:10.1139/l74-014

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Fracture mechanics is a design philosophy which has evolved over the three decades since World War II and is beginning to find use in standard design. This concept for fracture-safe design recognizes the general existence of flaws in engineering materials and provides an analytical basis for prediction of the mechanical behavior of a structure constructed of a flaw-bearing material.This article reviews the basic concepts of fracture mechanics. The material parameters, such as plane-strain fracture toughnessKIcare derived and the experimental technique for obtainingKIcis presented.The impact of fracture mechanics on engineering practice,i.e. material selection and fabrication, mechanical and structural design, and nondestructive testing is also examined.

ISSN:0315-1468    

DOI:10.1139/l74-015

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Hydrological data for the design of the Churchill Falls 5225-MW hydro-electric power development in Labrador, Canada comprised a 10-year record. Extensive statistical correlation studies using data from rivers up to 500 miles (800 km) distant were undertaken to expand this record to 43 years. Subsequently, stochastic generation of stream-flow, utilizing Beard's method, was adopted to expand the length of record and to provide multiple sets of flow data for use in energy and revenue studies. The generated data influenced the operational rules and reservoir capacity because it produced additional values for rare events (e.g. spill, water shortage) which are not well defined in a short record.

ISSN:0315-1468    

DOI:10.1139/l74-016

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

The dynamic analysis of a structure subjected to a random forcing function from a source such as earthquake, blast, or wind requires the use of a numerical integration technique. The efficiency and accuracy of the technique employed is of great importance for both research and practical design. The more effective methods of numerical integration belong to the category designated as ‘predictor-corrector’ methods. A systematic method is presented for the derivation of single-point and multiple-point predictor-corrector formulae. It is shown that most of the methods of numerical integration presently employed in structural dynamics are single-point predictor-corrector methods. A scheme of iteration is usually employed for the solution of the difference equations obtained by the application of these methods. It is shown that for problems in structural dynamics, it is not necessary to use an iterative scheme; a process of elimination is feasible and also gives considerable economy in computation time. It is further shown that the choice of an appropriate multi-point method for the numerical integration of the equations of motion of an elastic system can lead to a considerable saving in computation time and cost. One such multi-point method is presented, and its truncation error and stability are examined.

ISSN:0315-1468    

DOI:10.1139/l74-017

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

Empirical interaction equations are recommended in various specifications for the design of biaxially bent beam-columns. In this paper, the strength requirements specified in the Canadian Standards Association Standard S16-1969 for the plastic design of biaxially loaded beam-columns are compared with theoretical relations. It is shown that the S16-1969 provisions lead to unduly conservative designs when applied to thin walled square and circular hollow structural sections. Based on the theoretical relations, simplified interaction equations are proposed herein, which are both satisfactory and far less conservative.

ISSN:0315-1468    

DOI:10.1139/l74-018

出版商:NRC Research Press    

年代:1974

数据来源: NRC

摘要:

This investigation is a study of some of the factors which affect the ability of a plastic pipe to support earth loads. Some of the factors that were considered are the strength of the pipe and the soil conditions.Two series of laboratory tests, using two soil densities, were conducted on two types of plastic pipes that had six wall thicknesses. Deflection gauges were used to measure changes in the inside diameter due to an external load that was applied on the buried specimens.The results indicated that loose soil fill will produce about 70% more vertical deflection in a pipe than dense soil fill. Also, it was observed that vertical deflections can best be assessed by considering the resistence of the pipe to membrane forces rather than bending moments as stipulated in the A.S.T.M. Specifications.

ISSN:0315-1468    

DOI:10.1139/l74-019

出版商:NRC Research Press    

年代:1974

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l74-020

出版商:NRC Research Press    

年代:1974

数据来源: NRC