摘要:

The design and nonlinear dynamic analyses of four coupled wall prototype structures are presented. Two ductile partially coupled and two ductile coupled wall structures are considered, each having reinforced concrete and steel coupling beams. The design of each of the prototype structures was based on the provisions of the 1995 National Building Code of Canada. Nonlinear dynamic analyses of each structure, using four different scaled earthquake ground motions are presented and the results discussed. Comparisons of the responses of the structures with concrete and steel coupling beams are made, demonstrating the advantages of using steel beams to couple reinforced concrete walls.Key words: composite construction, coupled wall, diagonally reinforced concrete coupling beam, "flexure critical" steel coupling beam, seismic design, "shear critical" steel coupling beam.

ISSN:0315-1468    

DOI:10.1139/l98-015

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Computer simulation has been successfully implemented in the area of construction management. However, this success has generally been limited to the academic arena with the industry lagging far behind. This failure is partly due to the inherent complexity of general simulators and their inability to abstract the underlying modeling fundamentals. Special purpose simulation (SPS) is a framework developed to address the stated drawbacks by focusing on the needs of the construction practitioner. The idea is to build modeling environments tailored to the specific requirements of a given industry domain. This paper presents the development and implementation of a construction dewatering analysis framework based on the ideas of SPS. Object-oriented design and graphical user interfaces are used in the development of an abstraction layer between a steady state hydrological model and the user. The integration capability of the framework are then presented by constructing an optimization module and linking it to the main modeling environment. A case study is provided to demonstrate the usefulness, intuitiveness, and validity of the framework.Key words: simulation, special purpose simulation, construction dewatering, optimization, computer applications.

ISSN:0315-1468    

DOI:10.1139/l98-016

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

An important feature of ship design is the ability to describe the structural behaviour of the hull and to accurately predict its ultimate strength. Research on the ultimate strength of hulls has been carried out by many experimental research groups. Recently, the consensus reached is to simulate the behaviour of the hull by loading a box girder up to its ultimate strength. A box girder was tested at the Royal Military College of Canada. The objective of this experiment is to study the structural behaviour and compare the experimental results with the predictions of two computer codes. The construction of the model follows typical hull construction methods. The girder was subjected to pure bending until failure occurred. Provisions were taken so that collapse would occur due to buckling and not to plastic failure. Residual stresses and initial geometrical imperfections were measured and considered in the analysis. In previous publications, details of the design, fabrication, and loading were presented. In this paper, the experimental results are described and discussed.Key words: box girder, ship's hull, bending, ultimate strength, residual strength, residual stresses, initial imperfections.

ISSN:0315-1468    

DOI:10.1139/l98-017

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

This paper presents results of a study the goal of which is to evaluate the impact of rainfall forecast errors on real time control (RTC) of combined sewers in the Québec Urban Community (Q.U.C.). Firstly, we analyzed the impact of different levels of uncertainty on the probability to generate overloads in combined sewers and on the optimal overflow volume. The effects of the spatial distribution of errors on overloads and on overflow volumes have also been studied. Secondly, we modified the system management decision criteria in order to reduce the overload probability and to avoid possible backflows. This modification consisted of reducing the maximum allowable flow in the pipes of the sewer network. The results obtained showed that despite the negative impacts of forecast errors on overloads, this simple method preserves the efficiency of predictive integrated management. This ensures a safety margin on the possible backflows due to meteorological forecast errors.Key words: overflow, real time, control, combined sewers, forecast, errors, rain, overloads, backflows

ISSN:0315-1468    

DOI:10.1139/l98-021

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

This bench-scale study investigated the nitrogen-removal capabilities of two different biological process configurations treating methanogenic-state landfill leachate containing up to 1200 mg N/L of ammonia. The first configuration was a pre-denitrification system known as the modified Ludzack-Ettinger (MLE) process. Large clarifier sludge recycle flows, set to yield clarifier recycle ratios of 7:1 and 8:1, were evaluated as a means to reduce effluent NOxconcentrations. A pre- and post-denitrification system, known as the four-stage Bardenpho process, was the second configuration evaluated. The MLE systems (20 day aerobic solids retention time (SRT)) were capable of producing effluent containing about 50 mg N/L of ammonia and 200-235 mg N/L of total inorganic nitrogen (ammonia + NOx) when treating leachate containing approximately 1200 mg N/L of ammonia. In contrast, effluent from the four-stage Bardenpho system contained less than 1 mg N/L of ammonia and 15 mg N/L of NOx, when treating 1100 mg N/L ammonia leachate. An aerobic number 1 SRT of 20 days (total aerobic SRT approximately equal to 40 days) was used with aerobic number 1 and clarifier sludge recycle ratios of 4:1 and 3:1, respectively. The ammonia-removal potential of both systems was clearly demonstrated but each system also showed certain disadvantages, characteristic of each process.Key words: ammonia-N, anoxic denitrification, leachate treatment, nitrification, pre-denitrification.

ISSN:0315-1468    

DOI:10.1139/l98-018

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Lake Saint-François is a relatively shallow fluvial lake of the St. Lawrence River with numerous deep channels. This complex system has been considerably altered from its pristine state 150 years ago. Currently, the water level is stabilized and the flow is regulated; important areas have been dredged and the major part of its outflow is diverted through the Beauharnois canal. The evolution of water levels shows a trend towards stabilization as required for ship traffic in the St. Lawrence Seaway and for hydropower production. With the construction of the Moses-Saunders dam in 1960, the flow of the river could be regulated; changes occur in the seasonal pattern of the flow. Ancient stage-discharge relationships were recreated to describe the impact of the 1849 damming and of the present level stabilization. Stabilization of the water level has favored the growth of submerged plants. Manning's friction coefficient was used to show that plant biomass has doubled since 1920; the onset of biomass increases corresponds to a water level stabilization event. The distribution of wetlands in the Lake Saint-François area was drastically modified by the water level rise caused by the 1849 damming. New wetlands were created and pre-1849 wetlands, located on what are currently shoals in the central part of the lake, have totally disappeared.Key words: Lake Saint-François, St. Lawrence River, impact of civil works, flow discharge regulation, water level regulation, wetland flooding cycle, submerged macrophyte, ecosystem reaction, civil work histo

ISSN:0315-1468    

DOI:10.1139/l98-019

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The objective of pavement design, just as with the design of other structures, is to provide economical designs at specified levels of reliability. Methods that yield designs with different levels of reliability are undesirable, and over the course of time design approaches in the United States have converged toward the load and resistance factor design (LRFD) format in order to assure uniform reliability. At present the LRFD format has been implemented in concrete, steel, wood, and bridge design specifications. In this paper, reliability concepts are used to illustrate the development of an LRFD format for fatigue design of flexible pavements. It is shown that 10 candidate pavement sections designed against premature fatigue failure according to standard practice using the DNPS86 software do not have uniform reliability. It is demonstrated that uniform reliability can be achieved by using the LRFD format. The work reported is based on assumed variations of pavement layer properties and on analytical formulation; field verification was not attempted.Key words: LRFD, reliability index, fatigue, partial safety factors, flexible pavement design.

ISSN:0315-1468    

DOI:10.1139/l98-024

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

The economic and efficient operation of a hydroelectric generating station requires an accurate description of the head-power-discharge relationship for each turbine. Of the information required to determine this relationship, absolute discharge is the most difficult to measure and the most susceptible to measurement error. For low-head hydroelectric plants, the velocity-area method is often used. This method consists of traversing an array of current meters across the intake to obtain a grid of velocity measurements. The location of the metering points is central to the accuracy of the discharge estimate. The codes governing the performance testing of hydraulic turbines require the metering plane to be located in conditions that cannot be met for low-head hydroelectric plants. In spite of this, the codes are still applied. In this paper a densely spaced array of Ott meter data, collected according to the German (DIN) code, are used to examine the velocity profiles at the entrances of low-head hydroelectric turbine. In addition, these data are interpolated using cubic splines to estimate the time-averaged velocities required to compute discharge according to ASME (PTC-18) code. Interpolated data are also used to examine an alternative method of metering low-head plants based on Gauss-Legendre quadrature integration. The velocity profiles observed are significantly different from those assumed by the German and ASME codes to determine metering locations, which raises questions about the applicability of these codes to low-head plants. The results indicate that a Gauss-Legendre quadrature integration of a 4 × 5 grid of metering points estimates discharge more accurately than the German code, which requires a 7 × 12 grid. The suggestion is the location, and not simply the number of metering points, is central to the accuracy of a discharge estimate through a low-head hydroelectric plant.Key words: low-head hydroelectric turbine, performance testing, head-power-discharge relationship, Ott meter, Gauss-Legendre quadrature integratio

ISSN:0315-1468    

DOI:10.1139/l98-027

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

Analytical studies are carried out on the elastic torsional response of single- and multi-storey building models subjected to earthquake motion. Effects of both the natural and accidental torsion are considered. The results of analysis are compared with the design provisions of the National Building Code of Canada (NBCC). It is shown that the NBCC provisions for the design of resisting elements on the flexible side are overly conservative. On the other hand, provisions for the design of elements on the stiff side are conservative in some situations and inadequate in others. Modifications to the design provisions are suggested which give design forces closer to the results obtained from a dynamic analysis, and are at the same time simpler than the existing provisions. It is shown that the ratio of the uncoupled torsional and translational frequencies is an important parameter governing the torsional response and it would be a good practice in design to achieve a value greater than 1 for this ratio.Key words: earthquake response, natural torsion, accidental torsion, elastic torsional response, design for torsion.

ISSN:0315-1468    

DOI:10.1139/l98-031

出版商:NRC Research Press    

年代:1998

数据来源: NRC

摘要:

In a previous study on the elastic torsional response of building models subjected to earthquake motion, it was shown that the current provisions of the National Building Code of Canada for design against torsion induced by earthquakes are quite conservative for the flexible edge of the building, but may be inadequate for the stiff edge. Based on the results of studies on the elastic response, a new set of design provisions was suggested. The present study deals with the inelastic torsional response of single- and multi-storey buildings designed according to the suggested provisions. Effects of both the natural and the accidental torsion are considered. It is shown that, given the complexity of inelastic response, particularly that of multistorey buildings, the suggested provisions can reasonably be used for the torsion design of single-storey buildings, as well as of multistorey buildings that are asymmetric in plan, but otherwise fairly regular.Key words: earthquake response, natural torsion, accidental torsion, inelastic torsional response, design for torsion.

ISSN:0315-1468    

DOI:10.1139/l98-032

出版商:NRC Research Press    

年代:1998

数据来源: NRC