摘要:

In Canada, flooding due to the rise in water levels upstream of an ice jam, or the temporary exceedance of the flow and ice-carrying capacity of a channel upon release of an ice jam, has resulted in the loss of human life and extensive economic losses. Ice jam mitigation is a component of river ice management which includes all activities carried out to prevent or remove ice jams, or to reduce the damages that may result from an ice jam event. This paper presents a brief overview of measures to mitigate the damaging effects of ice jams and contains a discussion on their application to Canadian rivers.Key words: controlled ice breakup, flood control, ice jams, ice management, river ice.

ISSN:0315-1468    

DOI:10.1139/l90-081

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The formation and influence of compressive membrane action in reinforced concrete slabs is discussed. An experimental program is described, in which two large-scale slab specimens were tested under concentrated midspan loads. One slab was restrained against lateral expansion at the ends, while the other was free to elongate. The laterally restrained specimen developed high axial compressive forces, which resulted in a significant increase in flexural stiffness and load capacity. A nonlinear analysis procedure was used to model specimen behaviour. The analysis method was found to adequately represent important second-order effects, and thus gave reasonably accurate predictions of load–deformation response and ultimate load.Key words: analysis, concrete, deformation, load, membrane, reinforced, slabs, strength, tests.

ISSN:0315-1468    

DOI:10.1139/l90-082

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

An experimental investigation is described in which a large-scale reinforced concrete plane frame is tested to study factors contributing to its nonlinear behaviour under short-term loading conditions. The test results indicate that frame behaviour can be significantly affected by second-order influences such as material nonlinearities, geometric nonlinearities, concrete shrinkage, tension stiffening effects, shear deformations, and membrane action. A nonlinear frame analysis procedure, previously developed taking these mechanisms into account, is shown to accurately predict most aspects of behaviour, including deflection response, ultimate load capacity, and failure mechansim. Aspects of the theoretical modelling which are in need of further improvement are also identified.Key words: analysis, behaviour, deformation, frame, large scale, nonlinear, reinforced concrete, strength, test.

ISSN:0315-1468    

DOI:10.1139/l90-083

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper presents the results of tests on nine reinforced concrete slab-coupled structural wall subassemblages subjected to gradually applied reversing displacements simulating earthquake loadings. Two-third scale direct models of Taylor's Specimen No. 1 were used to study the effect of the following parameters in three phases: Phase 1, the effect of providing stirrups around the longitudinal slab steel; Phase 2, the effect of providing shallow reinforced concrete longitudinal and transverse concealed beams; and Phase 3, the effect of providing longitudinal drop panels. The experimental behaviour of the specimens is reviewed and discussed and suitable design recommendations are presented for strength and stiffness of slab–structural wall systems along with some practical guidelines to control damage in the coupling slab at higher levels of imposed deformations.Key words: coupled reinforced concrete slab–structural wall systems, damage, degradation of strength and stiffness, ductility ratio, earthquakes, gradually applied reversing displacements and loads, punching shear failures, reinforcement details, shallow coupling beams, yield lines.

ISSN:0315-1468    

DOI:10.1139/l90-084

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

The Limestone Generating Project was reactivated in 1985. Part of the development of the project was to review and implement, if feasible, potable water treatment facilities for the construction community of Sundance. The source water, from the Nelson River, is of reasonably good quality. The turbidity, however, ranges from 4 to 70 nephelometric turbidity units (NTU), averaging 15.2 NTU. Following preliminary and pilot plant studies, a high rate, deep bed direct filtration system was proposed and constructed to reduce turbidity to acceptable levels. A key feature of the plant is its portability. Owing to the innovative design, the three filters can be easily transferred for use at future construction sites on the Nelson River. This paper reviews and discusses the design, construction, operation, and costs of the plant.Key words: construction, design, direct filtration, high rate, Nelson River, operation, portability, turbidity.

ISSN:0315-1468    

DOI:10.1139/l90-085

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

In this paper, the authors are proposing a unified approach for the analysis of tridimensional structures with partial stiffness joints. The proposed approach allows for the quick modification of a software in order to take into account partial stiffness joints. After a review of the theory, we present two matrices to correct the fixed-end shear of flanges with partial stiffness joints. One of the matrix is concerned with bending, and the other deals with torsion. We also present two general cases of loading (bending and torsion) for the design of fixed-end shear and demonstrate how a tridimensional finite element can easily be modified to account for partial stiffness joints. We finally present a numerical technique that can generate equivalent nodal shear for situations where loads are partially distributed on one finite element of beam.Key words: analysis, joints, finite elements, software, matrix, stiffness, structure. [Journal translation]

ISSN:0315-1468    

DOI:10.1139/l90-086

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Some problems are described in connection with the survey of currents in an estuary influenced both by tides and runoff (the upper estuary of the St. Lawrence River, Canada). The use of numerical modelling is proposed as a reliable and cheap alternative to intensive hydrographic field surveys. A two-dimensional finite element hydrodynamic model with moving boundaries (drying–wetting) is outlined. An application of this model to the St. Lawrence River between Lotbinière and Sainte-Anne-de-la-Pérade is used as an illustration of the approach. The calibration method is first presented. Then, some results for a typical event (mean tide and river flow) are briefly described. Finally, emphasis is placed on the great potential of this approach to increase our knowledge (at least our insight) of estuarian systems as far as current-related phenomena are concerned (sediment transport, fish habitat, water quality, etc.).Key words: St. Lawrence River, hydrodynamics, modelling, simulation, finite elements, currents, drying and wetting, moving boundaries, tidal flow, estuary.

ISSN:0315-1468    

DOI:10.1139/l90-087

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

This paper presents some of the background to the new Canadian General Standards Board (CGSB) standard on the structural design of glass for buildings. It also describes strength testing of window glass at the Institute for Research in Construction of the National Research Council of Canada using three quite different testing machines. (i) A dynamic glass testing rig, with a large 2.35 m diameter piston, applies dynamic air pressures to large panes of glass in the vertical position. Results of 107 tests to failure show the considerable effect of loading rate on strength. (ii) A loading table applies linearly increasing pressures to panes of glass in the horizontal position. Results from 47 fifteen-year-old windows confirm assumptions about the deterioration of strength with in-service use in the new CGSB standard on the structural design of glass for buildings. (iii) A ring-on-ring tester applies linearly increasing loads to small 180 × 180 mm samples; the equivalent of coupon tests for steel or cylinder tests for concrete. The resulting uniform tensile stress fields avoid failures starting at the edges of the samples. Some results are given. Testing provides the basis for the structural design of glass cladding as it does for other structural materials. A great deal more testing of window glass is required.Key words: glass strength, window strength, testing, strength deterioration, rate effect, dynamic loading.

ISSN:0315-1468    

DOI:10.1139/l90-088

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

A numerical model to predict settling behaviour of fine sediment mixtures in a stagnant water column is described. Both single-grain settling mode and the floc settling mode are considered. The single-grain settling mode is analyzed by solving the unsteady, one-dimensional diffusion–advection equation numerically and the floc settling mode is examined by solving a coagulation equation expressed as a discrete equation in logarithmic radius space considering the differential settling as the only collision mechanism. The model results are compared with the laboratory experimental data of K. Kranck for both modes of sediment settling. The agreement between the model predictions and the experimental data is good. The model can be used as a basis for such practical applications as predicting sedimentation rates in reservoirs and settling basins.Key words: sediment mixtures, settling, flocculation, advection, diffusion, floc size distribution, primary particles.

ISSN:0315-1468    

DOI:10.1139/l90-089

出版商:NRC Research Press    

年代:1990

数据来源: NRC

摘要:

Recent vibration problems with floors used for aerobics have shown the need for better guidelines for structural design and evaluation. Such guidelines were introduced for the first time in the Supplement to the 1985 National Building Code (NBC), but more recent experience with one particular floor has shown the need for some improvements to these guidelines. The paper describes the investigation of the floor and the use of the floor to estimate the loading function for aerobics, and recommends changes to the NBC design criteria. The paper provides guidance on estimating parameters used in the criteria and discusses repair alternatives related to the floor problem.Key words: floor vibration, aerobics, design criteria, repair.

ISSN:0315-1468    

DOI:10.1139/l90-090

出版商:NRC Research Press    

年代:1990

数据来源: NRC