摘要:

The paper presents the development of a computer programVIEMfor the elastic analysis of multilayered elastic pavements under the action of arbitrary tire–pavement contact pressure distributions. The techniques adapted inVIEMprimarily involves the use of a two-dimensional numerical integration to integrate point load solutions over the distributed pressure after discretizing the contact area into a finite number of triangular or quadrilateral elements. Values of contact pressure are inputted at the node points of discretized area. Numerical verification ofVIEMindicates that numerical solution of high accuracy can be efficiently calculated for the elastic response of multilayered asphalt pavements. As a result, the determination of displacements and stresses (strains) can be achieved using a personal computer. With the use ofVIEM, a theoretical investigation is further performed to illustrate the effects of tire–pavement contact pressure distributions on the response of asphalt concrete pavements. Anin situmeasured tire–pavement contact pressure distribution is utilized in the investigation. The response of asphalt concrete pavements due to the action of this measured contact pressure distribution is examined and compared with that due to the action of a uniform and circular contact pressure distribution by taking into account the influences of moduli and thicknesses of structural layers. The results of this investigation confirm theoretically a general consensus that details of the contact pressure distribution affect stresses and strains near the surface of the pavement, whereas the response in the lower layers depends mainly on the overall load. In particular, the contact pressure distributions have a significant effect on the horizontal tensile strains at the bottom of thin asphalt concrete layer which control the fatigue failure of asphalt pavements.Key words: tire–pavevment interaction, three-dimensional stress analysis, asphalt concrete pavements, numerical integration, multilayered elastic solids, point load solution.

ISSN:0315-1468    

DOI:10.1139/l95-103

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

This paper discusses the development and the implementation of a neural network for the condition rating of rigid concrete pavements. The condition rating scheme employed by Oregon State Department of Transportation was used as the basis for the development of the network presented. A training set of 298 cases was used to train the network. The network adequately learned the training examples with an average training error of 0.011. A testing set of 3902 cases was used to check the generalization ability of the system. The network was able to determine the correct condition ratings with an average testing error of 0.022. The network ability of dealing with noisy data was also tested. Up to 40% noise was added to the data and introduced to the network. The results showed that the network presented could accurately identify condition rating relationships at high level of noise. Finally, a statistical hypothesis test was conducted to demonstrate the system's fault-tolerance and generalization properties.Key words: neural networks, condition rating, condition index, rigid pavements, pavement distresses, pavement maintenance, fault-tolerance, generalization, noisy data.

ISSN:0315-1468    

DOI:10.1139/l95-104

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

A practical method for incorporating realistic flexible connections in plane frame analysis, including the effect of connection sizes and shear deflection, is presented. The general algorithm can be easily implemented in a standard plane frame analysis program and, once implemented, it can be an ideal tool for production work in the steel industry. Connection stiffness is programmed directly into the analysis using the moment–rotation equations developed by Frye and Morris or may be entered separately as data. Practical application of this method of analysis is demonstrated by modifying a standard plane frame analysis program to include the effect of flexible connections. Solutions obtained using this modified program,CPlane, were verified against the findings of Moncarz and Gerstle. A simple plane frame structure was analyzed under various lateral load intensities for different connection assumptions. It was found that the inclusion of connection behavior significantly altered the internal force distribution and design of the structure.Key words: connections, matrix frame analysis, moment–rotation relations.

ISSN:0315-1468    

DOI:10.1139/l95-105

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

This paper describes the results of an analytical study of linear and nonlinear behaviour of ductile coupled shear walls with openings, under seismic loading. The walls in a typical building were studied and assumed to be ductile. They were designed, calculated, and detailed in compliance with the National Building Code of Canada 1990 (NBC) and the Canadian concrete code CAN3-A23.3-M84. The results of the elastic analysis show, as expected, that the concentrated force at the top specified by the NBC does not accurately simulate upper-mode effects, at least for this type of structure. A spectral analysis covering the five first modes, as described in the NBC, seems more suitable for coupled shear walls with openings with a period of more than 1.5 s approximately. The results of the nonlinear analysis show that application of the overstrength factor to the wall as recommended by CAN3-A23.3 greatly improves its behaviour and prevents tensile failure of the wall, although it does not always guarantee the desired sequence of plastification in the case of severe earthquakes. Application of the factor does, nonetheless, limit plastification of the wall to lower levels and keeps rotational ductility in beams and walls to a reasonable level.Key words: coupled shear walls, openings, reinforced concrete, ductility, overstrength factor, earthquake, building codes.[Journal translation]

ISSN:0315-1468    

DOI:10.1139/l95-106

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

A nonlinear three-dimensional finite element model was developed to study the complex behavior of ungrouted and grouted concrete block masonry prisms under axial compression. The model detects crack initiation and traces crack propagation in the masonry assemblage. Variable strengths for blocks, mortar, and grout were used to study the effect of the mechanical properties of prism constituents, and their combinations, on the prism strength and modulus of elasticity. The effect of the number of courses was also investigated. The results of the finite element analysis were used to develop simplified relationships to predict prism strength and modulus of elasticity. Good agreement was observed between the available experimental data and the predicted prism strengths.Key words: compressive strength, concrete blocks, failure modes, finite element, masonry, modulus of elasticity, prisms.

ISSN:0315-1468    

DOI:10.1139/l95-107

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The purpose of this paper is to demonstrate that labyrinth spillways can be a better option than rectilinear ones. The stages that have led to development of the labyrinth spillway are briefly reviewed as are applicable design and calculation principles. Discharge flow diagrams given by Hay and Taylor, Darvas, Lux and Hinchliff, and Magalhaes and Lorena for a trapezoidal labyrinth weir are compared. Calculation procedures and design diagrams were automated, making it possible to study flood routing through a labyrinth spillway and compare its performance to that of an equivalent rectilinear spillway. A real case was used for validation: routing through the trapezoidal labyrinth weir selected for the Keddara Dam in Algeria was compared with routing through the rectilinear spillway of the initial design. Dimensions, discharge values and expected maximum heights show calculated results agree with results of experimental studies of the structure and confirm that technically the labyrinth spillway is an attractive option. Labyrinth spillways can be particularly attractive for upgrading existing developments to satisfy more demanding design flood criteria in the limited right-of-way of an existing spillway. The Sainte Brigitte-des-Saults development in Quebec on the Nicolet Sud-Ouest River is a good case in point.Key words: flood control works, spillway, labyrinth weir, polygonal weir, nonrectilinear weir.[Journal translation]

ISSN:0315-1468    

DOI:10.1139/l95-108

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The hydraulic jump in a linearly contracting channel is studied in relation to choking flow. For a contraction intended to perform under supercritical flow, choking is an important design consideration because of the increase of flow depth and modified upstream conditions. Based on the momentum equation, a relation for the sequent depths ratio is determined and verified with extended experiments. Further, the mechanisms of both hydraulic jump and the choking flow are described. The wall surface profile is shown to be similar and equal to the profile of the classical hydraulic jump for a relatively small contraction rate. The lengths of roller and jump are determined, and substantial agreement with the classical jump is again found. The choking of a channel contraction is discussed as the limit condition of the hydraulic jump. A simplified model is shown to agree with observations. A design equation for choking is proposed.Key words: channel, choking, contraction, hydraulic jump, supercritical flow, water flow.

ISSN:0315-1468    

DOI:10.1139/l95-109

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The daily net basin supply of the large reservoirs of Hydro-Québec is currently computed by the water balance equation that relies, in particular, on gauge measurements. The number of gauge and their location heavily depend on simplified hypotheses that generate many errors in the computation. Also, for various technical reasons, the daily net basin supply can be missing. These problems greatly affect Hydro-Québec's real-time management of water resources. In this paper, we present a procedure that allows the estimation of the daily net basin supply of Hydro-Québec reservoirs, taking into account the different constraints of real-time forecasting. The approach is based on combined forecasts from two multiple regression models. It appears that this methodology gives good results and constitutes a considerable improvement in comparison with classical models and intuitive procedures usually employed in real-time forecasting. An application of the procedure on the daily net basin supply of three reservoirs (Baskatong, La Grande 3, and Outardes 4) is finally presented and gives satisfactory results.Key words: forecasting, real time, net basin supply, combined forecasts, weighted averages.

ISSN:0315-1468    

DOI:10.1139/l95-110

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The effects of biological treatment (ozonation followed by biological activated carbon filtration (BAC)) on chlorine demand and on formation of trihalomethanes (THM) and total organic halides compounds (TOH) were studied at the Sainte-Rose water treatment facility, Laval. The plant influent is a surface water with a dissolved organic carbon of 6–7 mg/L. Results showed that ozonation marginally reduced (0–6%) short term chlorine demand but that BAC filtration reduced it by 40–55%. Ozonation versus BAC filtration was found to effect THM and TOH formation differently from the removal of the chlorine demand. THM (4-h contact with chlorine) and TOH formations were reduced by 48–60% and 39%, respectively, via ozonation. With BAC filtration, THM and TOH formations were reduced by 20–34% and 16%, respectively, with respect to the ozonated influent. For all essays, an initial significant decrease in residual chlorine was followed by an increase in TOH and subsequently in THM. The initial chlorine doses used for measuring the chlorine demand were found to have an effect on the final results. An increase in the initial chlorine dose resulted in a higher chlorine demand as well as in higher THM and TOH formations. The effect was found to be more profound at chlorine doses less than 3 mg Cl2/mg total organic carbon.Key words: chlorine demand, chlorination by-products, trihalomethane, total organic halides, ozonation, filtration, biological activated carbon.

ISSN:0315-1468    

DOI:10.1139/l95-111

出版商:NRC Research Press    

年代:1995

数据来源: NRC

摘要:

The behavior of a steel frame may be affected significantly by the moment versus rotational deformation (M–φ) behavior of its beam-to-column connections. Some of the effects of connection behavior are described and demonstrated. Because connection behavior is nonlinear and relatively difficult to model analytically, generally applicable analytical behavior models are not available. Nor, despite the availability of more than 300 experimentally measured connectionM–φ data sets, are generally applicable empirically based behavior models available. Consequently, connection behavior continues to be accounted for only crudely in North American design specifications and in frame design. This paper describes a three-step strategy that would eventually permit theM–φ behavior of beam-to-column connections to be accounted for explicitly and routinely in steel design specifications and thus in frame design. The first step, to express connectionM–φ behavior in a compact form suitable for incorporation into frame analysis software, has been demonstrated by curve fitting 274 experimentalM–φ data sets to a specially developed function that requires only six parameters to describe connection behavior. The second step, to illustrate graphically the ranges ofM–φ behavior exhibited by the common connection. types, and thereby to help designers to develop a "feel" for connection behavior, has been demonstrated by comparing theM–φ plots to the EUROCODE3 connection classification boundaries. The third step, to blend the standard connection geometries that have been developed in several countries into an international menu of standard connection geometries and, eventually, to generate and curve fit reliable experimentalM–φ data for all of the standard connections, is summarized.Key words: beam-to-column connections, connection behavior, steel frames, structural analysis, steel design.

ISSN:0315-1468    

DOI:10.1139/l95-112

出版商:NRC Research Press    

年代:1995

数据来源: NRC