摘要:

A complete time history response dynamic analysis is carried out to establish the design seismic loading for the Harbour Centre building in Vancouver. The building has an elevated observation deck and restaurant offset from the centre of the structure. The paper describes the steps and considerations involved in the dynamic analysis such as the dynamic modelling of the structure, the choice of input ground records and the interpretation of the computed results. Whenever possible, the calculated values are compared with the 1975 National Building Code of Canada requirements to provide a proper perspective of the various approaches in establishing design loads for this building.

ISSN:0315-1468    

DOI:10.1139/l76-011

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

On August 8th 1974, infrared photographic data of the hot water plume at the Gentilly nuclear powerplant were obtained from an aerial survey of the St. Lawrence River. Important parameters such as the longitudinal decrease of temperature or lateral spread of the rejected water become available together with hydraulic and thermal ambient conditions.At first, a three-dimensional model, already developed at the Massachusetts Institute of Technology, was applied to the actual volume of water rejected and predicted a dilution rate much higher than the actual one. The use of a different geometric scheme has reduced the gap between predicted and actual values. The same scheme has been tried on a two-dimensional model. The two-dimensional approach is justified by consideration of the bottom topography.The discussion of results concerns: first, the establishment of an adequate geometric scheme and second, the error brought by the two-dimensional approach.

ISSN:0315-1468    

DOI:10.1139/l76-012

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Flow-induced vibrations are characterized as dynamic response, self-controlled and self-excited vibrations, the latter two being the principal subjects of this paper. Such classification is shown to be a helpful guide for designing against destructive vibrations. While the obvious choices of increased stiffness or additional damping may prove effective in some cases, counter-examples are presented. A change in structural geometry which modifies the flow characteristics may be the best or only avenue for eliminating vibration problems in service.The general nature of mathematical models of these phenomena is presented briefly as well as those aspects of hydro-elasticity which distinguishes it from aeroelasticity. In particular, the effects of virtual mass are emphasized.A variety of different problems are reviewed with an effort to summarize and interpret current knowledge and to provide some physical insight. Specifically treated are stability of fluid-conveying pipes, vibrations of hydraulic gates, valves, and seals, and the singing of propellor blades, guide vanes, and control surfaces. In each case, methods of alleviation are discussed.

ISSN:0315-1468    

DOI:10.1139/l76-013

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The complete seismic design process of certain important structures based on time-history dynamic analyses is traced from the initial preliminary design stage through the final stage of predicting lifetime performance to strong motion earthquakes. Emphasis is placed upon (1) selection of sound design procedures, (2) consideration of field and laboratory evidence, (3) application of present day knowledge, and (4) recognition of uncertainties involved in the complete process. It is concluded that meaningful predictions of performance can be made only when formulated in a probabilistic sense.

ISSN:0315-1468    

DOI:10.1139/l76-014

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A series of dye injection experiments were carried out near the surface in the coastal waters of lakes Erie, Ontario, and Simcoe. The purpose of the experiments was to determine whether the relative dispersion in these regions was similar to that obtained in other oceanographical experiment. Rhodamine BA dye was injected at a constant rate (approximately 150 mg/s) at a depth 1 m below the surface from a raft anchored in 9 m of water (approximately 1.5 km offshore) for 6 to 8 h. Two-dimensional dye plume concentrations were measured at cross sections 60 to 830 m from the source. Relative dispersion coefficients were determined numerically from the measured concentration profiles. The horizontal dispersion coefficients (80 to 4100 cm2/s) were comparable to oceanographical values and exhibited a 1.33 power growth with distance from the source. Vertical dispersion coefficients were very small (less than 1 cm2/s) and relatively independent of distance from the source.

ISSN:0315-1468    

DOI:10.1139/l76-015

出版商:NRC Research Press    

年代:1976

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l76-016

出版商:NRC Research Press    

年代:1976

数据来源: NRC