摘要:

The object of this paper is to present charts for the ultimate strength design of L-sections subjected to combined normal force and bending. The method of derivation of these charts is briefly described. It is general and applicable to other odd-shaped sections. It also conforms to the basic assumptions adopted in the CSA Standard A 23.3-1973. The charts can be used either for the determination of the dimensions of the section or for the check of its capacity.

ISSN:0315-1468    

DOI:10.1139/l76-054

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

This state-of-art paper reviews the concept of limit states design. Following a brief review of statistical definitions the sources of variability in reinforced concrete structures are reviewed. Methods of defining structural safety are reviewed. Following a derivation of the procedures used to compute load andfactors, a series offactors compatible with the 1975 National Building Code of Canada load factors are computed. With the exception of the value for shear the newfactors are lower than the current American Concrete Institute and Canadian Standards Association values by about the amount of the ratio of load factors in National Building Code of Canada and American Concrete Institute. The computedfor shear is considerably lower than the corresponding value from the American Concrete Institute Code. An Appendix traces the development of the American Concrete Institute load andfactors.

ISSN:0315-1468    

DOI:10.1139/l76-055

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The longitudinal shear failure of the slab of composite beams is constrained to occur at a predetermined shear surface. A method for calculating the longitudinal shear capacity of the slab of simply-supported steel–concrete composite beams is presented. The method is based on analyzing the stresses at failure of the concrete elements located at the slab shear surface.A design chart based on estimating the transverse normal stress required within the concrete slab to achieve the full ultimate flexural capacity of the composite beam is proposed. Alternatively, using elastic–plastic stress distribution across the concrete slab, the longitudinal compressive force due to bending and hence the applied moment can be predicted for any longitudinal shear capacity of the slab. The proposed design and analysis when compared to previous tests and analysis showed good agreement.The slab width and the shear span of the composite beam are found to be two important parameters which cannot be neglected when estimating the longitudinal shear capacity of the slab. These two parameters have been neglected in the empirical solutions previously adopted.

ISSN:0315-1468    

DOI:10.1139/l76-056

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A semi-graphical simplified solution to give results similar to the classical solution to the problem of concentrated loads on elastic cantilever slabs, made of isotropic material, is presented. This method, whose validity is checked by other well established methods of analysis, is expected to provide accurate and quick results to the problems of overhanging slabs of box girders, subjected to concentrated loads.

ISSN:0315-1468    

DOI:10.1139/l76-057

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A lumped-parameter mathematical model is formulated to represent the physical processes of the accumulating and melting snowpack within a drainage basin. Common theoretical descriptions of the processes represent snow accumulation and melt at a point, but computer-aided procedures facilitate spatial distribution of the model inputs and thus provide for a digital simulation of the basin-wide snowpack condition and melt with time. The model is treated on the basis of the energy flux and mass transfer processes relating to the average snowpack, across the snowpack–atmosphere and snowpack – ground surface interfaces. An awareness of the likely lack of the extensive meteorological data usually required for proper application of such models, necessitates reliance on a number of literature-cited and locally derived empirical snowmelt relationships in order to ensure a practical and viable model. Thus, auxiliary computer subroutines are formulated to provide for applicable options, depending on the availability of real-time data. The purpose of the snowmelt model is to serve as a monitor of net basin input, complementing an overall comprehensive integrated hydrologic system model for use in streamflow simulation. The model is calibrated and tested with real-time data in a Ministry of the Environment-IHD Representative Drainage Basin in southern Ontario. Its applicability in estimating maximum flood flows during spring runoff periods is demonstrated by imposing meteorological conditions favourable for continuous melting upon maximum snowpack storage conditions.

ISSN:0315-1468    

DOI:10.1139/l76-058

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

Due to the lack of stream guaging stations, a peak flow simulation based on physical and meteorological parameters was established for the area along the proposed Mackenzie Valley Highway between Fort Good Hope and the Dempster Highway.Calculations based on snowmelt and rain-on-snow runoff were developed, as it was found that the snowmelt of May or early June gave the yearly spring peak discharge.Due to the gap in existing flow data, a unit hydrograph method was developed to generate additional yearly spring peak discharges. Altogether, hydrographs from four gauged watersheds of similar physical conditions with size ranging from 250 to 8 200 mi2(648 to 21 240 km2) were used. In total, 46 yearly peak flows were generated.A regression equation of peak discharge computation was derived, using different hydrological and meteorological parameters. It was found that the most significant factors were the drainage basin area, the lake areas in the drainage basin, the water equivalent of the snow on the ground prior to melt, the rainfall in the period close to peak discharges, and the duration of snowmelt.The simulation was calibrated for drainage basins between 100 and 10 000 mi2(250 to 25 000 km2).

ISSN:0315-1468    

DOI:10.1139/l76-059

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

A study of the relationship between hydraulic characteristics of streams and selected aquatic animal populations was undertaken in the Blue Springs Creek. The Blue Springs Creek is unregulated, free of evidence of pollution, and is an International Hydrologic Decade Representative Basin.The study included two phases of investigation. The preliminary phase involved the collection of field data on aquatic animal populations and hydraulic characteristics at selected stream sampling locations. These data were analyzed to determine the influence of specific hydraulic characteristics upon the animal populations sampled. It was found that the average size (D50) of streambed material has an important influence on the animal populations studied. It was also concluded that the animal populations sampled were not significantly dependent upon values of Reynolds Number, Froude Number, temperature, relative roughness, and average velocity of flow determined from study data.These preliminary results were tested during the second phase of the study. Data for the tests were obtained by altering streambed material size at selected sampling locations. The tests showed that an increase in average size of streambed material resulted in an increase in biological diversity index at a point. Conversely a decrease in the biological diversity index at a point resulted from a decrease in the average size of streambed material.

ISSN:0315-1468    

DOI:10.1139/l76-060

出版商:NRC Research Press    

年代:1976

数据来源: NRC

摘要:

The effects of agitation and retempering on some properties of fresh and hardened concrete are considered.Data are presented on the influence of agitation and retempering with an air-entraining agent on the workability, compressive strength, and air void system in hardened concrete.The results indicate that although agitation reduces air content and increases the spacing factor, the original parameters can be regained by proper retempering. It is shown that any loss in compressive strength due to retempering is accompanied by an increase in potential durability due to the improvement of the air void system.

ISSN:0315-1468    

DOI:10.1139/l76-061

出版商:NRC Research Press    

年代:1976

数据来源: NRC

ISSN:0315-1468    

DOI:10.1139/l76-062

出版商:NRC Research Press    

年代:1976

数据来源: NRC