摘要:

To increase the depth of soil which covers a buried steel pipeline, the line can be lowered without cutting and welding. The degree of curvature in the new profile is the critical factor for controlling the resultant strains. Presented are two methods of calculating the required profile for a line containing high-pressure natural gas. One of the two is selected as being more efficient than the other and is compared with other known methods. Finally, a case history using the new method is presented.Key words: pipelines, gas pipelines, structural analysis, stress analysis, axial stress, axial strain, deflection, curvature, profiles.

ISSN:0315-1468    

DOI:10.1139/l87-109

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

By considering the thirtieth highest hourly volume (30HV) as the design hour volume, this study reexamines a commonly used method of predicting the 30HV as a function of the annual average daily traffice (AADT) volume. Based on Alberta's highway system data, some common limitations of the traditional 30HV–AADT model are pointed out. Also included in the analysis presented is a proposed alternative model which utilizes July/August traffic data to estimate the design hour volume. The alternative model appears to provide more accurate prediction results and it also eliminates the need of subjectively classifying the roads into various groups as required by the 30HV–AADT method.Key words: annual average daily traffice, design hour volume, highway design, road classification, traffic volume counts, transportation.

ISSN:0315-1468    

DOI:10.1139/l87-110

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The objective of this paper is to study the impacts and quantify the various losses due to the presence of toll stations. For this purpose a survey was conducted on the Champlain toll bridge which connects Montreal Island and the suburban South Shore area. The presence of toll stations imposes restrictions on the free movement of traffic and leads to speed-change cycles, idling, queuing, and excess travel time with direct increase in user costs. The impact of the geometric design of the toll station is also studied with respect to the various losses.The quantification of the various losses is achieved by using queuing theory and simple mathematical relations. The losses are to be considered for two very important reasons; first the losses are incurred by the commuters and second the additional user cost sometimes exceeds the actual toll fee. The results of this study indicates that substantial energy savings could be achieved along with better environmental conditions by either eliminating existing tolls or improving (redesigning) them. In constructing new transportation structures where above losses are likely to occur, the additional user cost due to the losses should be taken into consideration during economic analysis.Key words: fuel consumption, fuel emission, geometric design, idling, queuing, toll station, toll fee, travel time, user cost.

ISSN:0315-1468    

DOI:10.1139/l87-111

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The introduction of limit states design philosophy and the ever growing demand for higher permissible loads for overload vehicles or special permit vehicles necessitates a thorough investigation of the behaviour and live load distribution characteristics of bridges beyond the working stress range. Evaluation of the live load moment capacity at ultimate utilizing elastic load distribution factors is neither realistic nor logical, as the distribution factors should reflect the ultimate structural/load responses including nonlinear behaviour, load redistribution due to yielding, etc.The purpose of this paper is to study load distribution characteristics of a slab-on-girder bridge model at ultimate loads and to develop load distribution factors for the ultimate limit state which include load redistribution, nonlinear behaviour, and other effects.Key words: load distribution factor, ultimate limit state, load redistribution, nonlinear behaviour, slab-on-girder bridge, OHBD truck.

ISSN:0315-1468    

DOI:10.1139/l87-112

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

This paper presents the key observations and conclusions from the evaluation of an innovative "loose-fit" composite, post-tensioned concrete wing-girder bridge proposed for an elevated interstate highway expansion in an urban environment. The evaluation program included both testing to destruction of a 1/2-scale model of a partial span as well as construction monitoring and field testing at service load levels of a full-scale prototype two-span bridge. Results of both construction measurements and loading tests were compared with analytical predictions. Laboratory tests showed the composite behavior of the wing-girder joint to be fully effective and a high level of load transfer between wings to be present. Recommendations for modification of the prototype design are made to improve constructibility, durability, structural performance, and economy.Key words: box girder, bridge, post-tensioned, prestressed concrete, reinforcement, stresses, temperature, tendons.

ISSN:0315-1468    

DOI:10.1139/l87-113

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The use of disaggregate models in modelling intercity passengers mode choice behaviour has emerged over the past 20 years. In an attempt to encourage this use, the present paper addresses the advantages and disadvantages of the disaggregate approach as opposed to the conventional aggregate techniques. The results of a literature review in this regard indicate that disaggregation is statistically and behaviourally necessary to model human travel behaviour while being sensitive in selecting the unit of analysis. The paper also compares the logit analysis with other modelling techniques available for application in order to identify the most suitable one. A critical review of previous modelling efforts in the U.S. and Canada, based on the disaggregate logit analysis is presented to demonstrate the applicability of this technique to modelling intercity passengers mode choice behaviour. Some modelling drawbacks and the general findings of the studies are emphasized to provide useful insight for future modelling considerations.Key words: behavioural, disaggregate, logit analysis, mode choice, models, passenger travel.

ISSN:0315-1468    

DOI:10.1139/l87-114

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A new, simple, hypoelastic, and anisotropic stress–strain relationship is proposed for modeling the behaviour of concrete subjected to a general state of monotonic loading. The proposed model reduces to an incremental orthotropic model if the direction of the principal stress axes remains constant. It also eliminates the inability of the orthotropic constitutive relationships to model the behaviour of concrete under a general state of monotonic loading when the principal stress axes rotate during the loading process.The capability and reliability of the proposed model for the analysis of structures in which the principal stress direction does not rotate is verified. A finite element computer program is formulated and used for the nonlinear analysis of planar concrete specimens tested by Kupfer, Hilsdorf, and Rusch and by Tasuji and reinforced concrete panels tested by Vecchio and Collins. The results obtained from the analytical models are in good agreement with the corresponding experimental results.Key words: biaxial stresses, constitutive relationships and failure criteria, cracking and postcracking response, finite element analysis, hypoelastic model, orthotropic model, plain and reinforced concrete.

ISSN:0315-1468    

DOI:10.1139/l87-115

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A study is made of the seismic behaviour of tuned equipment–structure systems where one or both of the system components experience inelastic deformation. The response is determined using coupled and decoupled models of the system. The effect of various parameters such as mass ratio and yield level on the system response is evaluated.It was found that the mass ratio and yield level of the tuned inelastic system are the key parameters affecting the response of the coupled system. The response of the primary system is found to be insensitive to the variation of the yield level of the secondary system. In addition, the response obtained using uncoupled analysis of the equipment and structure system is generally higher than the response obtained using coupled analysis and may result in grossly overdesigned systems.Key words: dynamic, seismic, response, tuned, coupled, equipment, structure, earthquake, inelastic.

ISSN:0315-1468    

DOI:10.1139/l87-116

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

A design standard for structural glass in the limit state design format is currently being developed under the auspices of the Canadian General Standards Board. The standard will be calibrated to a target level of reliability expressed in terms of a reliability index. The selection of this reliability level presents some special problems because the loading is dynamic, the structural response is geometrically nonlinear, and the strength is highly dependent on time, size, and loading history. Selection of safety level so as to achieve a social and economic optimum is described. The optimum reliability index is 3.0, corresponding to a lifetime failure probability of 0.0014, when the social and economic cost of failure is between 15 and 70 times the initial cost. Optimal ranges of applicability over cost for a pair of importance factors (0.8 and 1.25) are also determined.Key words: glass, design, standard, code, calibration, reliability, optimization, importance factor.

ISSN:0315-1468    

DOI:10.1139/l87-117

出版商:NRC Research Press    

年代:1987

数据来源: NRC

摘要:

The main objective of this research is to find a simple and precise methodology for the stochastic generation of flow series having statistical behaviour similar to the registered or reconstituted historical series. The common statistical parameters are the mean, the variance, the auto- and cross-correlations, and, under particular conditions, the skewness coefficient. A procedure to disaggregate annual series to lower levels (monthly or seasonal) is also presented. Finally, the article describes the general computer model utilized for the synthetic generation.Key words: synthetic generation, flow series, disaggregation, computer model.

ISSN:0315-1468    

DOI:10.1139/l87-118

出版商:NRC Research Press    

年代:1987

数据来源: NRC