摘要:

Household hazardous waste (HHW) disposal contributes significantly to the cost of HHW collection programs. In addition, disposal of HHW can contribute to the toxicity of leachate from landfill, heavy metals in ash from waste incinerators, and heavy metals and toxic organic compounds in composted material and sewage sludge. Other options such as product substitution, waste minimization, reuse, or recycling should be considered to help reduce costs and disposal concerns. An estimate of the volumes and types of HHW accumulated by collection programs, their recycling and reuse options, and treatment and disposal requirements are presented.Recycling, reuse, or disposal of collected wastes depends upon the market for the recycled material, the availability of recycling or disposal facilities, transportation facilities, and the potential to reuse the waste material without treatment. The costs of disposing of HHW are relatively high but can be offset by co-funding from manufacturing associations and local businesses. A disposal fee could also be applied to household hazardous products, thus placing the cost burden on the purchaser.Public education can assist in reducing the volumes of HHW and public pressure is also forcing companies to eliminate hazardous compounds in household products. If effective consumer education continues, the increasing demand for non-hazardous substitutes will significantly reduce the volume of household hazardous products, consequently reducing HHW.Key words: household hazardous waste, waste disposal, waste recycling, waste reuse, waste management.

ISSN:0315-1468    

DOI:10.1139/l93-071

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Large-scale laboratory tests of the evolution of bedforms in sand beds, under directional irregular waves, carried out at the National Research Council Canada, are described. Preliminary observations indicate that the directionality of the waves is not an important factor; bedforms remained largely two-dimensional under all but transitional conditions. Incident wave height and period, probably combined as a wave orbital amplitude near the bed, seems to be the most important factor in determining bedform dimensions, followed by theD50sand size on the bed. Sand gradation may be unimportant.Key words: seabed, sand, water waves, bedforms, morphology, roughness.

ISSN:0315-1468    

DOI:10.1139/l93-072

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

This paper presents a reliability analysis of wood I-joists for both strength and serviceability limit states. Results are obtained from a finite element analysis coupled with a first-order reliability method. For the strength limit state of load-carrying capacity, multiple failure modes are considered, each involving the interaction of several random variables. Good agreement is achieved between the test results and the theoretical prediction of variability in load-carrying capacity. Finally, a procedure is given to obtain load-sharing adjustment factors applicable to repetitive member systems such as floors and flat roofs.Key words: reliability, limit state design, wood composites, I-joist, structural analysis.

ISSN:0315-1468    

DOI:10.1139/l93-073

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

In this study, wood composite I-beams consisting of F11 slash pine flanges and either hardboard or particleboard webs were fabricated and evaluated for flexural stiffness. Prior to fabrication, both the web and flange materials were evaluated for flexural stiffness. The mean modulus of elasticity of the flange material was 16 900 MPa, while that for the particleboard and hardboard was 4250 and 4450 MPa respectively. The mean effective modulus of elasticity for the particleboard-webbed beams was 16 300 MPa and for the hardboard-webbed beams was 16 400 MPa. The implications of the findings are discussed.Key words: wood composites, I-beams, characterization.

ISSN:0315-1468    

DOI:10.1139/l93-074

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The first step required in the design sequence for a hydraulic structure is selection of the design discharge. The size and cost of the structure will be directly related to the magnitude of this value. If the selected discharge is too large, the structure will be uneconomic; if it is too small, it will be unsafe. The optimum design corresponds to the point where the cost of the structure and the cost of exceeding the design discharge is a minimum. Ideally, the optimizing process should be carried out for each structure. For practical reasons it is not always possible to do this. In such cases, design flood frequencies are used which have apparently been satisfactory for similar structures in the past. Some typical flood frequency values for various structures are given in this paper, along with the rationale for differences in values for different kinds of structures.Key words: design floods, frequency, economics, hydraulic structures.

ISSN:0315-1468    

DOI:10.1139/l93-075

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Microcomputer finite element analysis of reinforced concrete slab systems can now be routinely performed to produce realistic numerical simulation of three-dimensional structural behaviour. However, an efficient use of this approach requires an automated integration of design and analysis procedures. Guidelines for proper finite element modelling of slab systems are first presented along with simple post-processing algorithms to perform automatically the design or verifications from the analytical results. Numerical applications on simple slab systems subjected to uniform and concentrated loads are then used to illustrate the relative performance between finite element analyses and the equivalent frame method.Key words: microcomputer, reinforced concrete slab, finite element method, structural design.

ISSN:0315-1468    

DOI:10.1139/l93-076

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Escalation can account for a substantial part of construction costs. Therefore forecasts of the amount of escalation are required for budgetary and bidding purposes. This paper examines methods for forecasting construction escalation using statistical time series methods. Time series of construction cost indices are used as a proxy of construction cost escalation. The application of time series methods, their limitations, and their effect on the risk of cost escalation are demonstrated and evaluated. The analytical methods available are only useful in forecasting for short construction projects in stable conditions. This is because none of the methods can forecast escalation caused by unpredictable occurrences such as outbreak of war or certain government action. Construction cost escalation remains a risk to be borne by either the contractor or the owner, or both, depending on the terms of the contract; any logical approach to minimize the risk is worthwhile.Key words: construction cost escalation, cost indices, time series forecasting, exponential smoothing. Box–Jenkins methods, dynamic regression, Statistics Canada.

ISSN:0315-1468    

DOI:10.1139/l93-077

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

This paper describes recent developments related to a new return flow algorithm built into the Water Resources Management Model (WRMM) of Alberta Environmental Protection. An earlier return flow allocation method which was used in the WRMM did not always give satisfactory results. It was essential to fix this problem, since correct modelling of the return flows in overall river basin management is of crucial importance. The new return flow algorithm offers more reliable return flow allocation without detrimental effects on the overall model solution. This model is a major river basin planning tool in western Canada used to analyze responses of a river basin to varying operating policies or structural developments. It is a simulation model with a nested optimization subprogram. As a deterministic, steady state, and surface water allocation model, it normally relies on the estimates of natural flows and water demands throughout the river basin. The WRMM can provide quick simulations of any river basin with any number of components within a microcomputer environment. The model is used in ongoing river basin management studies in Alberta and other western provinces in Canada.Key words: water management, computer modelling, simulation, optimization, irrigation.

ISSN:0315-1468    

DOI:10.1139/l93-078

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

Several Canadian wood truss manufacturers expressed a need to develop technical information to initiate the fabrication and acceptance of wood trusses made with glued-laminated timber (glulam) members and connected by punched metal plates. In collaboration with industrial participants, Forintek Canada Corp. developed a program for testing and analysis of metal plated glulam trusses. Twelve 3/12 pitched chord trusses and three parallel chord trusses, all 13.7 m long, were designed by three different plate manufacturers. All truss fabrication took place at a single truss manufacturing plant. Trusses composed of 79 mm wide and 152-229 mm deep glulam members connected by 16-gauge punched metal plates were tested to failure. The ratio of ultimate to design load averaged 3.5, and varied between 2.7 and 4.4. Both wood and plate failure modes were observed. The results suggest that the sizes of glulam members used in this study are structurally suitable for use with 16-gauge metal connector plates.Key words: wood, trusses, glued-laminated timber, truss plates, strength, stiffness.

ISSN:0315-1468    

DOI:10.1139/l93-079

出版商:NRC Research Press    

年代:1993

数据来源: NRC

摘要:

The tension and compression zones of moment plate connections were studied separately by testing branch plate and hollow structural section connections under each type of loading. Square hollow section flanges were reinforced by doubler plates fillet-welded all around. The results from 13 specimens tested in tension indicate that branch plate to reinforcing plate width ratio is an important parameter in joint behaviour. The dominant failure mode was punching shear of the reinforcing plate. The importance of reinforcing plate and HSS wall thicknesses was apparent from the results of 13 specimens tested in the compression series. The capacities of specimens in all but one test in this series were limited by failure of the HSS webs.Key words: hollow structural sections, W-shape, columns, beams, connections, experimental, design, steel.

ISSN:0315-1468    

DOI:10.1139/l93-080

出版商:NRC Research Press    

年代:1993

数据来源: NRC