摘要:

Existing methods of calculating the web shear capacity in plate girders are examined and their applicability to large rectangular duct analysis is investigated. It is suggested that a modified Wagner theory, combined with the method developed by the NACA, offers a rational approach to the evaluation of web shear capacity in rectangular ducts.

ISSN:0315-1468    

DOI:10.1139/l80-011

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A 1:600 scale acoustic model of Kincardine Harbour originally built by the National Research Council of Canada (NRCC) was delivered to the Applied Dynamics Laboratory at McMaster University late in 1976. After preliminary testing, a second acoustic model was built to a scale of 1:200 in order to narrow the range of acoustic wave frequencies required to simulate the observed lake wave climate. Scale selection and the necessary acoustic frequency band are discussed. The response at eight locations inside the model harbour was measured in this frequency band and the harbour wave amplification determined. A comparison between the acoustic model results and the hydraulic model results (previously carried out by NRCC) is presented.A public opinion survey of recent users of Kincardine Harbour was carried out during the winter of 1976–1977. The purpose of this survey was to identify potential problems in the harbour. The survey was focused on (a) harbour entrance and resonator, (b) offshore breakwater, (c) rubble-mound breakwater, and (d) inner harbour. The results indicated that the users were generally of the opinion that the resonator had decreased inner harbour oscillations, but that it presented a navigational hazard, particularly at night.On the basis of the survey, a utility function was proposed; it indicates an average condition of the harbour in relation to outside wave conditions. Tests on the acoustic model were then carried out. Results of those tests showed that model beach reflectivity was comparable to that of the prototype, but reflectivity of the model breakwater was relatively low. When resonators were installed wave amplification in the harbour was reduced.

ISSN:0315-1468    

DOI:10.1139/l80-012

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

This paper presents the results of an experimental investigation aimed at the development of moment connections for precast reinforced concrete members. Two types of moment connections were tested. Type 1 moment connections are made by welding reinforcing bars protruding from the column to a steel plate welded to the tension reinforcement of the beam. Type 2 moment connections are made by welding a continuity plate to two other steel plates, one welded to the reinforcement of the beam and the other affixed to the face of the column by means of studs. The testing program comprised 15 specimens including four monolithic joints of the same geometry as specimens of types 1 and 2, introduced to compare the behaviour of cast-in-place and precast structures.The test results indicate that type 1 moment connections have almost the same strength and stiffness as monolithic joints but are less ductile. In type 2 moment connections, brittle fracture occurred at bending moments much lower than the ultimate strength of the beams. Some modifications are suggested in the paper in order to improve the behaviour of the two types of moment connections.

ISSN:0315-1468    

DOI:10.1139/l80-013

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Many communities in Canada's northern areas rely on a trucked supply of water and pickup of human waste from bucket toilets or holding tanks. The high capital costs of conventional piped water and gravity sewer systems and the lack of funds necessitate the continued use of trucked systems for many years, particularly in the smaller settlements in permafrost regions. Promising methods of cheaper piped collection of wastes, such as vacuum and pressure sewers, may be used in the near future. Both require only small quantities of water for the transport of solids. Human wastes in plastic bags ("honey bags") are now disposed of at a dump, in waste pits, or lagoons. Satisfactory treatment methods for these strong wastes and for wastes from holding tanks, vacuum, and pressure sewers are needed.Results of a 5 year study simulating a waste pit in permafrost show that it merely serves as a holding tank and does not provide satisfactory treatment. Pathogens are likely to remain viable in such a pit for many years. Anaerobic digestion of undiluted human waste has been found feasible at 20 °C, but is not likely to be a practical and economical solution for communities using trucked systems. Properly located, constructed, and operated waste pits are recommended for these situations.Anaerobic digestion of vacuum sewer wastes, which are much less dilute than sewage, is feasible at a temperature of 20 °C and with a minimum detention time of 30 days. The process may be applicable at lower temperatures, provided a high proportion of methane bacteria is maintained in the reactor. This may be accomplished either by longer detention time or through the anaerobic contact process. It is recommended that a pilot installation be constructed together with a vacuum sewer system in a northern community using anaerobic digestion as the method of treatment of vacuum sewer wastes.

ISSN:0315-1468    

DOI:10.1139/l80-014

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

The static and dynamic nonlinear response to internal pressurization, due to a loss-of-coolant type accident, is investigated for a "cut-and-cover" prestressed concrete horseshoe-shaped containment in a clay medium with and without a stiffening (concrete – foamed concrete) jacket. The loading conditions considered are: (i) sustained prestress only, and (ii) sustained prestress and static–dynamic internal pressure. The yield condition used is the Drucker–Prager criterion. Axisymmetric finite-element analysis is carried out for various media patterns (concrete – foamed concrete – clay) using the computer code NONSAP. The results indicate considerable increase in structural integrity due to embedment.

ISSN:0315-1468    

DOI:10.1139/l80-015

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

In February, 1975, ayear study of five highland lakes (Big, Cheticamp, Gisborne, Long, and Surge Lakes) in the Wreck Cove area of Nova Scotia was initiated to determine the limnological effects of construction of a hydroelectric project. Almost 600 lake-water samples were used to monitor water-quality changes resulting from tunnelling, dam construction, reservoir clear-cutting, slashing, and burning, and establishment of access roads.The impact on Surge Lake was much more pronounced than on the other four lakes. Evidence strongly suggests that the significant water-quality changes in Surge Lake can be attributed to clear-cutting operations and construction activities (of longer duration and higher intensities in the vicinity of Surge Lake area in comparison with other areas) resulting in accelerated soil erosion, nitrification, and soil leaching. Also, the Surge Lake watershed had steeper slopes, and different vegetative cover.Nitrate, ammonia nitrogen, total and ortho phosphorus, calcium, magnesium, sodium, potassium, chloride sulfate, total solids, conductance, pH, suspended solids, and turbidity increased significantly in the lower-most lake (Surge) but only moderately in the remaining lakes. The relative rates and amounts of revegetation of exposed soils were also considered key factors in influencing the magnitude of changes in water quality of these highland (elevation 400 m) lakes.

ISSN:0315-1468    

DOI:10.1139/l80-016

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

Probabilistic models have become important hydrologic tools. However, increasing model complexity makes the connections between the model and the physical world more and more vague. This can lead to a de-emphasis of engineering judgment, since model validity is easily assumed when even partial verification must await future occurrences. A simple autoregressive model was used to generate stochastic flow sequences for the dam and reservoir being constructed on the Red Deer River in Alberta. The results from this model were compared with those obtained from a more complex autoregressive moving average (ARMA) model. Both models have similar deficiencies. It is concluded that since stochastic generation can never represent future conditions with certainty, the common practice of basing the hydrologic design of reservoirs on actually recorded data is usually the most valid procedure. However, stochastic streamflow generation can be used to give valuable probabilities of reservoir storage failure.

ISSN:0315-1468    

DOI:10.1139/l80-017

出版商:NRC Research Press    

年代:1980

数据来源: NRC

摘要:

A method of evaluating tensile bond and shear bond of masonry structures is presented. A new test procedure based on centrifugal force has been developed and the principles involved are discussed.Results of tests on 30 tensile bond specimens using M, S, and N mortars are reported. Also, results from 20 shear bond specimens are presented.It is concluded that the test apparatus provides an acceptable means of evaluating tensile and shear bond strengths of masonry. The tensile bond of concrete block masonry is of the order of 517, 451, and 343 kPa for types M, S, and N mortars respectively. Shear bond strengths are of the order of 323 and 265 kPa for M and N mortars.

ISSN:0315-1468    

DOI:10.1139/l80-018

出版商:NRC Research Press    

年代:1980

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l80-019

出版商:NRC Research Press    

年代:1980

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l80-020

出版商:NRC Research Press    

年代:1980

数据来源: NRC