摘要:

The purpose of this paper is to describe an interactive computer graphics approach to the analysis and design of structures exhibiting nonlinear structural behavior. A general procedure for the nonlinear analysis of planar frame structures, which accounts for member yielding, is described. In addition, the graphics programs required to input an arbitrary planar structure, monitor the analytical procedure, and aid in evaluating the results of the incremental analysis are presented. A procedure for generating a color image of the deflected structure, where the color indicates the proximity to yield, is also presented. This interactive approach to a powerful analysis procedure, aided by graphic interpretation of input and analysis results, provides a practical desïgn tool.

ISSN:0315-1468    

DOI:10.1139/l79-011

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The paper deals with a procedure that can be used by a design standards committee to determine safety indices for structures and calculate optimum performance factors for limit states design. Six load components are considered: dead, sustained live, transient live, snow, wind, and earthquake load effects. The procedure is based on an approximation of the probability distributions by normal distributions in the design point situated on the failure boundary. The objective in selection of performance factors is closeness to a target safety level expressed in terms of the target safety index. A computer program was developed to be used in calibration. The procedure is illustrated by examples.

ISSN:0315-1468    

DOI:10.1139/l79-012

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Precast, prestressed segmental box-girder bridges are now accepted as an economical alternative for spans over 150 ft (46 m). Decisions about cross-sectional dimensions made during preliminary design can have a substantial influence on the final cost of the bridge. To help the designer obtain an economical starting point for a final design, a program was written to determine section dimensions and midspan and pier prestressing steel areas to give minimum cost. Since a preliminary design is obtained, the analysis techniques and design criteria have been simplified to reduce computation. The design produced by the program will satisfy AASHTO specification requirements and the recommendations of the PCI Bridge Committee. The optimization algorithm used is the generalized reduced gradient technique. To demonstrate the program capabilities, three example problems are discussed. The results indicate that optimum span-depth ratios are approximately 24 for the cost ratios used. The cost of the optimum design does not seem to be too sensitive to the ratio of concrete cost to prestressing steel cost.

ISSN:0315-1468    

DOI:10.1139/l79-013

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

A flow-damage model has been developed to predict the annual probable damage due to basement and street floodings in relatively flat urban areas where pumping is required. The damage cost is obtained by integrating damages due to high as well as low probability storms. Annual capital recovery costs are also computed. The flow simulation is based on the Road Research Laboratory model, the Muskingum method, and a relaxation procedure for computation of surcharge conditions.The model can be used for design purposes or to evaluate existing systems. A suggested design procedure incorporating the flow-damage and installation cost models along with linear programming has been used to obtain an optimum design for a given pumped storm-sewer system. The optimal design is achieved when the combined cost of annual operating capital recovery, and annual probable damage is minimum. The design variables include the depths, slopes and diameters of the sewers. as well as sump area, rated pumping head, and discharge.

ISSN:0315-1468    

DOI:10.1139/l79-014

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

Numerous innovations in the use of structural steel alone or in combination with other structural components have been tried and proven in North America during the past two decades. In numerous other fields of endeavour, mass production allows refinement in both function and cost. However, the 'one-off' approach inherent in both architectural and structural design of buildings on this continent and the broad spectrum of projects (and clients) processed by any single consultant, in spite of any desired level of specialization, allow development of only the low end of the learning curve related to the use of a particular system.This paper sets out with two objectives: the first is to review some of the innovative structural framing systems for steel buildings, presenting the concepts and design details for review by others who only infrequently have opportunities to design a structure falling in one of these categories; the second is to review possible adaptations of these structural systems with the objective of achieving greater construction efficiency and (or) greater economy.Systems reviewed will include concrete-cored, gravity steel-framed structures with a number of alternative construction methods, staggered truss-framing systems, interstitially framed hospital structures with a review of economics and mechanical–structural interface aspects, the stub-girder framing system with Canadian alternatives, steel–concrete composite action of both vertical and horizontal structural members, efficient lateral load-resisting systems such as direct acting tension and compression bracing, including both exterior and interior applications, steel-plate shear walls as lateral load-resisting elements, and combinations of the above.Structural interface with other building components including wall components will receive considerable emphasis, but overall, ways and means of improving productivity in both design and construction will be the primary focal points and objectives of the paper.

ISSN:0315-1468    

DOI:10.1139/l79-015

出版商:NRC Research Press    

年代:1979

数据来源: NRC

摘要:

The difficulties in assessing the effects of water pollution on a salmon fishery are illustrated with the example of pollution in the lower Fraser River and the Chilko run of sockeye salmon. Changes in water quality in the lower Fraser affect the salmon as they migrate to sea as smolts and as they return to spawn. A procedure is presented for making a preliminary assessment of the effect of additional mortality induced by water quality changes on the average size of the run; ways of extending the analysis to estimate probable trends in water quality and the effects this would have on the salmon fishery are outlined.

ISSN:0315-1468    

DOI:10.1139/l79-016

出版商:NRC Research Press    

年代:1979

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l79-017

出版商:NRC Research Press    

年代:1979

数据来源: NRC