摘要:

Prestressed concrete ties offer an alternative to the timber ties which are used presently on North American open deck railway bridges. This paper presents the results of a field study of an open deck railway bridge equipped with precast prestressed concrete ties subjected to a special work train and regular railway traffic. The results of the study show that a train with smooth wheels does not overload the bridge deck. When wheel defects are present, the bridge deck loading is speed-dependent and consists of distinct static and dynamic components. Test results show that the tie design loads are underestimated. The impact on the bridge deck due to the defective wheels was also found not to amplify the response of the bridge longitudinal steel girders.Key words: bearing pads, impact load, railway bridge, load distribution, dynamic load factor, open deck, precast prestressed concrete, ties, wheels.

ISSN:0315-1468    

DOI:10.1139/l89-071

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The method of compound finite strip is applied for the three-dimensional analysis of corrugated soil–steel structures with and without curved stiffeners. Displacement functions are suggested for the analysis of soil–steel structures during and after backfilling. The eccentricity between the middle surfaces of stiffened elements and the adjacent shell elements is considered in the displacement functions so that the continuity of the shell is satisfied between the strips. The formulation presented herein incorporates the stiffness contribution of surrounding soil media directly in the strip element stiffness matrix. Examples of soil–steel structures are analyzed by the proposed method and the results are compared with experimental results.Key words: cylindrical shells, finite strip, soil–steel structures, stiffeners.

ISSN:0315-1468    

DOI:10.1139/l89-072

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The methods used to determine apparent diffusion coefficients and the appropriate parameters for modelling diffusion through compacted bentonite–water systems are assessed and discussed. The measured apparent diffusion coefficient can vary between methods. The discrepancies are shown to be due to heterogeneous diffusivities arising from the proximity of the surface of clay particles. Two different diffusivity pathways are identified and the diffusive flux is shown to be dictated by the charge of diffusing species, diffusion time, and soil fabric.Key words: apparent diffusion coefficient, methods, compacted bentonite, heterogeneous diffusion, parameters, pathways.

ISSN:0315-1468    

DOI:10.1139/l89-073

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Atomic Energy of Canada Limited is developing methods for the management and safe disposal of radioactive wastes. These wastes range from the highly radioactive (high-level) UO2fuel arising from the nuclear generation of electrical power to the low- and intermediate-level wastes arising from research in various Canadian institutions using radioactive isotopes. This paper reviews the current research programs on materials and processes for the immobilization and containment of UO2fuel wastes and the technical aspects of programs demonstrating the various technologies needed for implementing a disposal program for low-level wastes.Key words: waste management, radioactive, nuclear fuel waste, high-level waste, low-level waste, disposal, immobilization, glass, containment, siting, land burial, geological disposal.

ISSN:0315-1468    

DOI:10.1139/l89-074

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Aspects of scaling theory relating to the response of reinforced concrete structures under impact load conditions are reviewed. Details for modelling concrete and reinforcement, to be consistent with similitude requirements, are also discussed. A test program is described in which models of varying size were constructed, drop tested, and compared with prototype response. An analysis of the test data is made, indicating that, within certain limitations, the predictions of scaling theory are applicable to reinforced concrete subjected to extreme impact loads.Key words: cracking, impact, loads, modelling, reinforced concrete, scaling, stresses, structures, tests.

ISSN:0315-1468    

DOI:10.1139/l89-075

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Creating, enlarging and excavating a harbour can modify the dynamic response of the basin. A verification of the resonance modes is common practice before undertaking the related work. This can be done numerically if the necessary assumptions are justifiable. It can be done on a small-scale model if the basin has an irregular shape or if the depth varies from one area to the other.A computer-programmed analytical method of resonance modes is presented. It is derived from the direct measure principle of successive oscillation superposition used in the laboratory. Validation is obtained by applying the method to existing theoretical solutions and to the analysis of a small creek of the Gaspe Peninsula where the importance of refraction in the analytical results is demonstrated.Key words: harbour, vibration, agitation, ocean waves, diffraction, refraction, numerical model, application. [Journal translation]

ISSN:0315-1468    

DOI:10.1139/l89-076

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A simultion–optimization algorithm for sizing potential reservoirs on a river basin has been used to demonstrate the effects of the streamflow record length on capacity requirements. The sizing procedure involves the generation of synthetic streamflows and a reservoir reliability analysis. Two levels of reliability are present: the reliability in meeting water supply requirements, and the probability level associated with the final capacity selection. The procedure was applied to synthetic sequences generated from an 81-year inflow record and subsets of this sequence to produce frequency distributions of required capacities. The capacities with a 5% probability of exceedence were compared. Relying on short inflow sequences can lead to substantial overestimations or underestimations of capacity. A key factor is the presence of the critical period in the analysis. An open question remains regarding the effect of the final probability level selection on the range of capacities observed.Key words: design reservoirs, water supply, simulation, optimization, reliability, record length, synthetic streamflows.

ISSN:0315-1468    

DOI:10.1139/l89-077

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A method for simplifying irregular ground profile of roadway cross sections by a straight line is presented. The presented method does not affect the accuracy of earthwork volume computations. Two types of cross sections are considered: cut (or fill) and transition sections. For a cut (or fill) section, the simplified section is designed such that its area equals that of the original section. This is accomplished by adjusting the least-squares (LS) parameters. Three cases of adjustments that depend on the area of the original section and the unadjusted LS parameters are presented. These cases preserve the section type (cut or fill) and, as much as possible, the general shape of the original section. For a transition section, the simplified section is designed such that its cut and fill areas equal those of the original section. These conditions of equal areas are used to develop formulas for designing the simplified section directly. Application of the method is illustrated by numerical examples.Key words: roadway, cross section, irregular, least squares, linear profile, earthwork volume.

ISSN:0315-1468    

DOI:10.1139/l89-078

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

A total of 120 tests of forced radial flow hydraulic jumps have been analyzed in order to develop curves and equations for the design of radial stilling basins. The jump depth, the water surface profile, wave amplitudes, the allowable flare angle, and the jump length are defined in terms of entrance conditions, the baffle position, and the baffle height. An example design is given and compared with a USBR (U.S. Bureau of Reclamation) Type III stilling basin.Key words: forced hydraulic jump, radial flow, design, stilling basins, baffles, radial hydraulic jump, circular hydraulic jump.

ISSN:0315-1468    

DOI:10.1139/l89-079

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Atomic Energy of Canada Limited is investigating the concept of the disposal of high-level radioactive waste in an underground vault in an intrusive crystalline rock formation. The environmental impact of such a disposal is, to a large extent, dictated by geochemical processes involving rock-forming minerals, groundwater, and fission products and actinides in the waste. These various geochemical processes impact on the transport of contaminants, including radionuclides and chemically toxic elements, from a used-fuel disposal vault towards the biosphere. The extent and importance of the geochemical processes on contaminant transport are discussed. The predominant processes controlling the velocity of contaminant transport are the various geochemical interactions of the dissolved contaminant species with the minerals lining the surfaces of conductive fractures and fracture systems.Key words: radionuclide, uranium, nuclear contaminant, transport, sorption, diffusion, geochemistry, fission products, granite.

ISSN:0315-1468    

DOI:10.1139/l89-080

出版商:NRC Research Press    

年代:1989

数据来源: NRC