摘要:

A refined yet simple method is presented for the analysis of cold-formed metal shear diaphragms. Expressions for the deflections and fastener forces are developed based on an assumed mode of deformation in conjunction with a refined set of internal force distributions. The formulas are applicable to both 'direct' and 'indirect' shear-transfer cases. The generality and the accuracy of the derived expressions are illustrated in an application of the method to the analysis of eight diaphragms having a wide range of constructional details. The results of calculations for the diaphragm flexibility and strength are in good agreement with test results and with finite-element analyses.

ISSN:0315-1468    

DOI:10.1139/l79-028

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Hollow structural sections (HSS) have come into increasing usage for structural purposes over the past number of years. There are several reasons for this development, in particular, the advantages of such shapes from an architectural viewpoint, the strength inherent in a closed cross section, corrosion stability, and ease of maintenance. Due to their shape, the members are particularly suited for use as columns.This paper presents a review of typical HSS production methods used throughout the world today, with emphasis on the effect of several important parameters that vary with the production process. Following a general discussion of column strength theory and its application to HSS columns, the development of limit states design procedures for compression members is evaluated. Special attention is paid to the requirements of the standard CSA S16.1-1974, and the studies that led to these rules.Outlining briefly the philosophy of full-scale column testing and typical procedures that are followed in such work, the ensuing portions of the paper present detailed data from experimental and theoretical studies on Canadian-produced HSS sections. Column tests conducted on heat-treated shapes are compared to other data from similar tests on columns produced by a variety of manufacturing processes. It was generally found that the heat-treated shapes performed somewhat better than the cold-formed columns, considered as a whole, and that within the cold-formed data there was considerable variation between manufacturers. Comparison with data from column tests conducted in Japan and in Europe revealed that the Canadian shapes tended to fall within the upper portions of the data band.In closing, preliminary recommendations are presented for the evaluation of the strength of various manufactured HSS members in limit states design.

ISSN:0315-1468    

DOI:10.1139/l79-029

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Structural design to resist earthquakes is different from structural design for the more usual forces in that theloads are uncertainbut much larger than the elastic resistance of the structure; consequently, the engineer must be concerned with cyclic postelastic performance of materials and systems, ductility, and the stability of structures near ultimate loads.Cyclical tests on members and connections for steel moment-resisting frames indicatevery stable hysteresisin the plastic range, a very desirable characteristic. Moment-frame structures, however, are subject to large deflections with consequent damage to the point wheresecondary effectssuch asP-delta may become critical. Some observations have indicated that better performance can be obtained by combining the ductile steel frame with concrete shear walls or with steel-braced frames. Tests, both in Japan and California, suggest that large amounts of energy can be absorbed and large ductilities can be achieved by using eccentric connections with steel-braced frames.

ISSN:0315-1468    

DOI:10.1139/l79-030

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The 1971 census journey-to-work data supplemented by road-network data for 30 Canadian census areas are analyzed. The data are used to examine the degree to which the commonly used trip-generation and trip-distribution techniques might be used to synthesize journey-to-work patterns and the extent to which the parameters may be generalized across these urban areas.The extent to which intercensus-tract variations in labour force are explained by several separate measures of census-tract residential activity are analyzed by regression analysis. Dwelling-unit composition is isolated as the most effective predictor of census-tract labour force. These multiple regression equations explain from 96–99% of the intercensus-tract variations in labour force and the partial regression coefficients are consistent between census areas.Production-constrained and production-attraction-constrained forms of the gravity model are calibrated. Although conventional goodness-of-fit statistics suggest that these gravity models have a high degree of explanatory power, a detailed examination of the trip-interchange residuals shows that model performances are less than adequate. It is concluded that significant modifications to the traditional gravity trip-distribution models are required if interzonal travel demands are to be estimated with confidence.

ISSN:0315-1468    

DOI:10.1139/l79-031

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Frazil ice is generated in ‘supercooled’ water upstream of an ice cover, and presents an operational hazard to any water intake for hydroelectric and steam power plants and municipal water supplies.The electric heating of trash racks incorporated in water intakes is one of the recognized methods of preventing the deposition of frazil ice on the racks themselves and the ultimate (if allowed to continue unchecked) complete blockage of the intake. In this paper the authors treat the structural and electrical design and the in-service performance of an electrically heated trash-rack system at the Twin Falls Power Development in central Labrador.The power dissipated in the trash-rack heating system for each 50 000 kW machine was approximately 250 kW, i.e., some 0.7% of unit rating.The Twin Falls rack heating installation gave satisfactory performance over some 12 years of winter operation, since its placement in service for the winter of 1962–1963.

ISSN:0315-1468    

DOI:10.1139/l79-032

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Sewage lagoons are used in several communities of the Northwest Territories, Canada to provide low-cost sewage treatment. Information is sparse, particularly during winter, to prove the effectiveness of this method in arctic climates. The objective of this study was to evaluate the performance of lagoons in arctic regions by a study of the lagoon at Inuvik, N.W.T., over a 1 year period.Results of this study endorse the continued use of sewage lagoons as an effective and low-cost sewage treatment method for small arctic communities. In spite of some serious design and construction deficiencies, and several-fold increase in loading, the Inuvik lagoon has provided reasonable treatment at minimal cost over the past 15 years. Its ability to sufficiently reduce bacterial loads to the receiving stream must, however, be seriously questioned.

ISSN:0315-1468    

DOI:10.1139/l79-033

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

This note presents a procedure for estimating the probability distributions associated with cost estimates. The procedure is approximate but appropriate to the level of detail normally available.

ISSN:0315-1468    

DOI:10.1139/l79-034

出版商:NRC Research Press    

年代:1979

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l79-035

出版商:NRC Research Press    

年代:1979

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l79-036

出版商:NRC Research Press    

年代:1979

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l79-038

出版商:NRC Research Press    

年代:1979

数据来源: NRC