摘要:

The nonlinear stiffness equations that predict local and post-local buckling of plates and plate assemblies are given. These equations are validated by accurate predictions of independent test results. The elastic local buckling of longitudinally stiffened web plates in combined bending and compression is considered. Graphs which may be used to predict the optimum position of a stiffener are presented. The relationship between the area and second moment of area of a stiffener of finite dimensions that optimizes the local buckling coefficient is given for various eccentricities of end load. The post-local buckling of a longitudinally stiffened plate in uniform compression and pure bending is also considered. It is shown that the provision of a longitudinal stiffener, of proportions to enforce a node at the plate–stiffener junction, enhances significantly the postbuckling response of the plate with regard to the serviceability limit state, particularly for the case of pure bending.Key words: bending, compression, finite strips, local buckling, plates, postbuckling, stiffeners, webs.

ISSN:0315-1468    

DOI:10.1139/l89-095

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

This paper presents the design concept for a case study sanitary landfill on a site that would not normally have been approved owing to the presence of a high water table. In this design, the base of the landfill was intentionally placedbelowthe water table. A massive 2.5 m wide, 2.5 m high cutoff wall and a 0.3 m thick liner with hydraulic conductivities of approximately 5 × 10−10 m/s were constructed of recompacted glacial till to limit both groundwater intrusion into the landfill and leachate migration out of the landfill. In this case study, the landfill base was placed below the water table to (i) provide a relatively inexpensive source of cover material and (ii) use the hydrodynamic gradient from the high water table to help contain the leachate. Finite element modelling of the seepage and contaminant transport, for alternate designs for lined and unlined landfills placed above and below the groundwater table, is shown to confirm a previous, less-sophisticated, estimation that placing a lined landfill below the groundwater table has definite advantages in reducing both leachate seepage and contaminant transport.Key words: landfill, leachate, hydrodynamic containment, liners, compacted earth cutoff walls, seepage and contaminant transport modelling.

ISSN:0315-1468    

DOI:10.1139/l89-096

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The 1984 CSA standard for the design of concrete structures for buildings provided new seismic design and detailing requirements for concrete structures. Full-scale, reversed cyclic loading tests of reinforced concrete beam–slab–column subassemblages were carried out to investigate the seismic performance of frame structures designed with the latest Canadian code. The test results indicate the importance of including the influence of slab reinforcement in computing the beam capacity as well as the need to carefully design the joint regions for shear. The test results indicate the excellent performance of frame components designed withK = 0.7 (R = 4.0) and the poor performance of those designed and detailed withK = 2.0 (R = 1.5). The performance of subassemblages designed withK = 1.3 (R = 2.0) depends on the column to beam strength ratio and on the shear strength of the joints. Models to predict the flexural response as well as the shear response of key elements are described and the role of the spandrel beam in limiting the effective slab width is explained.Key words: seismic design, reinforced concrete, detailing, structures, codes.

ISSN:0315-1468    

DOI:10.1139/l89-097

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Governments have initiated wastewater treatment programs to solve the problem of water pollution. The goal is commendable, but the inevitable result is the production of sewage sludge which can be considered as waste. If it is buried, incinerated, or discharged in the sea, the problem is not solved and we are back to square one. Moreover, we have wasted a potentially useful substance. The only promising solution is the transformation of sewage sludge into fertilizers. This study shows that sewage sludge produced by water treatment plants can be used as an efficient forest fertilizer which increases the size and height of trees. The fertilization of larch tree samples in green houses using anaerobic sludge from the Valcartier Wastewater Treatment Plant resulted in a 300% increase in height and 210% increase in diameter.Key words: management, recycling, sewage sludge, anaerobic sludge, fertilization, water pollution, forestry. [Journal translation]

ISSN:0315-1468    

DOI:10.1139/l89-098

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

In the late sixties, several concrete producers in the Chicago area developed very high strength concrete. The compressive strength of this new type of concrete was increased gradually, and it is now possible to buy 100 MPa ready-mixed concrete in several places in North America. Of significant technological importance, very high strength concrete is becoming popular all over North America due to its profitability. As to why and how very high strength concrete is made, the readily available answers to the first question contrast with the predominately empirical approach that has characterized research into producing very high strength concrete up to now. In fact, there are no miracle mixes that will universally guarantee the availability of 100 MPa ready-to-use concretes. Nonetheless, some guidelines have been established that should be followed in order to avoid various pitfalls. In Canada, very high strength concrete is beginning to be used in the Toronto and Montreal areas. This paper summarizes the principal results obtained on two specific projects: the construction of an experimental column in Montreal in 1984, and the construction of Nova Scotia Plaza in Toronto in 1986.Key words: high-strength concrete, water/cement ratio, superplasticizer, silica fume, slag.

ISSN:0315-1468    

DOI:10.1139/l89-099

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

Hydrological models are now routinely used in planning, design, operation, and control of water resources systems. However, all models, no matter how complex, are approximations of thereal worldand consequently are subject to various levels of errors. The analysis of uncertainty in hydrological models can provide valuable insight into the limitations and advantages of various surface runoff models. The benefits derived from such an analysis are many: first, it provides the modeller with a direct estimate of runoff prediction errors under specific rainfall conditions; second, it enables the user to analyze the trade-offs between different rainfall-runoff models; and finally, it can provide useful information for the design of data collection systems designed to achieve a given level of performance. This paper describes the application of uncertainty analysis to rainfall-runoff modelling under noise-corrupted rainfall conditions. The statistical properties of surface runoff subject to noise-corrupted rainfall conditions are examined. Methods of analysis described in this paper include (a) derived probability distribution, (b) first-order analysis, and (c) Monte Carlo simulations. The techniques are applied to linear and nonlinear runoff models, including the unit hydrograph, and the Soil Conservation Service model.Key words: runoff, uncertainty, error analysis, statistics, stochastic modelling, first-order analysis, Monte Carlo simulation, SCS model, unit hydrograph.

ISSN:0315-1468    

DOI:10.1139/l89-100

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

This paper presents a review of current worldwide efforts in automation and robotization for construction. Over a dozen countries are currently involved in such research efforts to overcome mainly declining productivity, increasing labor costs, hazards in the workplace, and scarcity of skilled labor. Research and development progress of Japanese contractors is emphasized, as they are aggressively introducing robots on site. A number of their leading contractors are visited, and applications of robotic equipment utilized on building construction sites in Japan are summarized. The Canadian construction industry, existing in a harsh climate and affected by shortages of skilled labor and high labor costs, needs to carefully consider construction robotics in order to meet its changing needs. The characteristics of the Canadian environment are presented and factors that have a direct bearing on the feasibility and implementation of robotics are emphasized. Different methods for the evaluation of the value of a construction robot are presented and applied to a numerical example. Comparisons are then made between the U.S. and Canada. It is believed that, given existing technology, economical constraints will either force or impede the implementation of robotics.Key words: Canadian construction industry, construction robot, automation, building construction, productivity, feasibility.

ISSN:0315-1468    

DOI:10.1139/l89-101

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The Brooks Aqueduct is a very large elevated flume commissioned in 1914 by the Canadian Pacific Railway (CPR) to carry water at the rate of 25.5 m3/s over a valley 3.2 km wide and 20 m deep. Construction of the aqueduct permitted the irrigation of a 50 000 ha block of land within a region now known as the Eastern Irrigation District in southern Alberta. The flume is 6.5 m wide and 2.5 m deep with a curved cross section. It is supported by 1030 columns. A 3000 mm diameter inverted syphon near the outlet of the flume permitted the crossing of the CPR main line through the valley. All components of the aqueduct, including the shell of the flume, columns, syphon, and inlet and outlet structures, were constructed of reinforced concrete. The Brooks Aqueduct was abandoned in 1979 with the completion of its earth-fill replacement. Except for a 122 m section, removed to permit the construction of a county road, the old aqueduct still stands. It serves to remind us of the significant engineering accomplishments of the pioneer civil engineers who helped to realize ambitions to irrigate the vast plains of southern Alberta at the turn of the century. On May 28, 1988, the Brooks Aqueduct was named a National Historic Civil Engineering Site by the Canadian Society for Civil Engineering.Key words: Brooks Aqueduct, history.

ISSN:0315-1468    

DOI:10.1139/l89-102

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The Ontario Bridge Formula (OBF) is the basis for the regulation of highway truck weights in Ontario. Allowable loads on tandem and tridem axle groups increase with increasing axle group spread. Analyses of the moments induced in simple-span bridges by the allowable axle group loads show that the moments increase with the increasing loads allowed on wider axle spreads. Pavement damage load equivalency functions developed from the Canroad pavement test series are used to estimate the. pavement damage impacts of these allowable axle loads. Relative pavement damage is shown to increase by 50% for the range of loads allowed on tandem axle groups and by 125 % for the load range allowed on tridems. If equal pavement damage were used for regulating axle group loads, then the range allowed for tandems would be 15 400–16 500 kg, instead of the OBF-allowed 15 400–19 000 kg; and 19 100–20 000 kg, instead of the OBF-allowed 19 500–28 600 kg, for tridems.Key words: highway bridges, highway pavements, bridge loads, trucks, load equivalencies.

ISSN:0315-1468    

DOI:10.1139/l89-103

出版商:NRC Research Press    

年代:1989

数据来源: NRC

摘要:

The finite strip method is used to analyze three different kinds of simply supported highway bridges: slab-on-girder, two-cell box-girder, and rectangular voided slab bridges. Deck width from two lanes to four lanes are considered. The Ontario highway bridge design (OHBD) truck load is applied at the most critical location of the bridge. A total of 12 design curves are developed, corresponding to different bridge sections and deck widths. From these design curves, one can obtain the ratio of the maximum longitudinal bending moment to the equivalent beam moment.Key words: bridge decks, design curves, concrete, steel, finite strip, OHBD truck load.

ISSN:0315-1468    

DOI:10.1139/l89-104

出版商:NRC Research Press    

年代:1989

数据来源: NRC