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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

A comprehensive study on soil consolidation

Nayyeri Amiri, Shahin January 1900 (has links)
Master of Science / Department of Civil Engineering / Asadollah Esmaeily / In this research, soil consolidation is explored in a comprehensive analytical and experimental study. The pore pressure development and dissipation for clay at its liquid limit under one-dimensional compression was investigated using the mid-plane pore pressure measurements. In general, the Terzaghi’s theory of consolidation predicted the pore pressure dissipation and the percent consolidation accurately as long as the sample was in a normally loaded state. For a preconsolidated state however, the results obtained by Terzaghi theory are doubtful. Coefficient of consolidation for smaller pressures varied during consolidation, and although the soil was in a fully saturated state for relatively high pressure increments, the pore pressure developed was less than the applied pressure. Then, the effect of different pressure increment ratios on one dimensional consolidation tests has been studied. The secondary compression effects have been founded to increase as the pressure increment ratio is reduced. Consolidation of a clay layer delimited between sheets with small permeability was also investigated in this study. The consolidation theory of compressible soils usually assumes drainage-free boundaries. This change in boundary conditions at the drainage surface necessitates the use of an approximate technique for solution of the governing partial differential equation. In this study, the solution was obtained by using the Galerkin Method and compared with the “free drainage” case. As expected, the consolidation in the case of restricted drainage proceeds at a much lower rate. The compression consolidation behavior of trampled clays in a semi- saturated state was also analyzed in this research program. It is generally known that the type and energy of compaction bring about deviations in the soil structure and hence, in its engineering properties. Therefore, in the experimental phase of this study, soils were prepared by different trampling efforts and also by different compaction methods. Finally, a reasonably realistic theory of soil consolidation has been proposed and the effect of variable permeability and compressibility on the consolidation behavior was investigated followed by a mathematical treatment of the behavior. Subsequently, laboratory consolidation tests with mid-plane pore pressure measurements were conducted on different kinds of clay.
42

Modelling Intercity Travel Demand in the Quebec City – Windsor Corridor: A Study on the Effects of Local Accessibility Utilizing a Geographically Disaggregated Web-based Approach

Wong, Billy 11 December 2013 (has links)
This thesis presents a novel approach to evaluating intercity travel demand given the introduction of a new travel mode. A joint RP-SP survey is designed to collect both experienced and hypothetical travel decisions. The stated preference aspect of the survey evaluates the level-of-service attributes that influence intercity mode choice. Emphasis is placed on the effects of local accessibility by adapting a geographical disaggregation at the Forward Sortation Area (FSA). Survey distribution collected data primarily through the use of online social networks such as Facebook and Reddit in addition to an online marketing research survey panel. Intercity mode choice was modeled with Random Utility Maximizing (RUM) discrete choice models and is represented by Multinomial Logit (MNL) and Nested Logit (NL) choice structures. Key finding is that access to transit stations significantly influences intercity mode choices.
43

Modelling Intercity Travel Demand in the Quebec City – Windsor Corridor: A Study on the Effects of Local Accessibility Utilizing a Geographically Disaggregated Web-based Approach

Wong, Billy 11 December 2013 (has links)
This thesis presents a novel approach to evaluating intercity travel demand given the introduction of a new travel mode. A joint RP-SP survey is designed to collect both experienced and hypothetical travel decisions. The stated preference aspect of the survey evaluates the level-of-service attributes that influence intercity mode choice. Emphasis is placed on the effects of local accessibility by adapting a geographical disaggregation at the Forward Sortation Area (FSA). Survey distribution collected data primarily through the use of online social networks such as Facebook and Reddit in addition to an online marketing research survey panel. Intercity mode choice was modeled with Random Utility Maximizing (RUM) discrete choice models and is represented by Multinomial Logit (MNL) and Nested Logit (NL) choice structures. Key finding is that access to transit stations significantly influences intercity mode choices.
44

Analysis of the Low-bid Award System in Public Sector Construction Procurement

Bedford, Thomas 16 December 2009 (has links)
Canadian construction participants have long recognized that accepting the lowest price bid does not guarantee maximum value. Achieving a value-based procurement approach is a challenge, particularly for the Canadian public sector clients who are limited in their ability to evaluate the competitive bids based solely on the low-bid award system. Bid and cost data from 218 projects from three major public sector construction clients in the Greater Toronto Area are evaluated. Compared to the other clients, the cost escalation is significantly higher for the client that does not have a standard prequalification policy. Increased contractor competition (high number of bids) and a large price gap between low bid and other bids are correlated to higher cost escalation for the non-prequalifying client. Also, the organizational culture of the non-prequalifying client is less results-oriented. The research demonstrates the importance of prequalifying for clients that award based solely on the low bid.
45

FormWorks-Plus: Improved Pre-processor for VecTor Analysis Software

Sadeghian, Vahid 21 March 2012 (has links)
VecTor© is a suite of computer programs developed for nonlinear finite element analysis of reinforced concrete. A graphics-based pre-processor (FormWorks) was developed for 2D concrete membrane structures, greatly contributing to the software’s utility and success. However, modeling other types of structures is a time consuming process, requiring manual definition of the finite element mesh, loads and analysis parameters in standard text files. A user-friendly pre-processor is required for the entire suite of programs if they are to be of greater use to design engineers. The purpose of this study is to develop an updated version of FormWorks, FormWorks 3.5, which is more user-friendly and compatible with the improvements made in VecTor2 over the past ten years. In addition, an extended version of FormWorks, FormWorks-Plus, will be created for the remaining VecTor programs with a wide range of viewing features, and facilities for specification of node coordinates, elements, loads and material properties.
46

Modelling Departure Time and Mode Choice for Commuting in the Greater Toronto and Hamilton Area (GTHA): Evaluation of Dynamic Travel Demand Management Policies

Sasic, Ana 23 July 2012 (has links)
This thesis develops econometric models of departure time and travel mode choice to evaluate dynamic transportation policies. Dynamic policies affect travel attributes differently throughout the day. Both departure time and mode choice are modelled with Random Utility Maximizing (RUM) Generalized Extreme Value (GEV) discrete choice models that capture systematic and random heterogeneity. Departure time is represented by a heteroskedastic generalized extreme value model (Het-GEV) with overlapping choice sets. Studying the Greater Toronto and Hamilton Area (GTHA), models are estimated using Revealed Preference (RP) household travel data from the 2006 Transportation Tomorrow Survey (TTS). Empirical models are used to evaluate dynamic transit and road pricing policies. Results indicate that the models are capable of capturing mode and time switching behaviour in response to peak pricing policies. To alleviate demand while maintaining transit mode share, a road charge and a moderate, flat, transit fare increase throughout the morning peak are recommended.
47

An Investigation into the Flexural Behaviour of GFRP Reinforced Concrete Beams

Getzlaf, Douglas Donald 20 November 2012 (has links)
Non-corroding materials, such as Fibre-Reinforced Polymer (FRP) bars, are now being used as reinforcement for reinforced concrete structures in order to extend their lifetime and minimize maintenance costs. Because of the softer and brittle behaviour of GFRP bars, behaviour of structural members reinforced with this material is different than that of steel-reinforced members. In this study, 16 GFRP reinforced beams were constructed and tested under flexure and shear loads to failure. Effects of different variables, such as amount of longitudinal and lateral reinforcements, type of bars and concrete strength, were investigated for their effects. The flexural provisions of design codes, namely CSA S806-12, CSA S6-06, and report ACI 440.1R-06, were evaluated against the test data. The main provisions investigated are failure modes, ultimate strength, moment-curvature response, deflection, crack widths, and deformability.
48

FormWorks-Plus: Improved Pre-processor for VecTor Analysis Software

Sadeghian, Vahid 21 March 2012 (has links)
VecTor© is a suite of computer programs developed for nonlinear finite element analysis of reinforced concrete. A graphics-based pre-processor (FormWorks) was developed for 2D concrete membrane structures, greatly contributing to the software’s utility and success. However, modeling other types of structures is a time consuming process, requiring manual definition of the finite element mesh, loads and analysis parameters in standard text files. A user-friendly pre-processor is required for the entire suite of programs if they are to be of greater use to design engineers. The purpose of this study is to develop an updated version of FormWorks, FormWorks 3.5, which is more user-friendly and compatible with the improvements made in VecTor2 over the past ten years. In addition, an extended version of FormWorks, FormWorks-Plus, will be created for the remaining VecTor programs with a wide range of viewing features, and facilities for specification of node coordinates, elements, loads and material properties.
49

Modelling Departure Time and Mode Choice for Commuting in the Greater Toronto and Hamilton Area (GTHA): Evaluation of Dynamic Travel Demand Management Policies

Sasic, Ana 23 July 2012 (has links)
This thesis develops econometric models of departure time and travel mode choice to evaluate dynamic transportation policies. Dynamic policies affect travel attributes differently throughout the day. Both departure time and mode choice are modelled with Random Utility Maximizing (RUM) Generalized Extreme Value (GEV) discrete choice models that capture systematic and random heterogeneity. Departure time is represented by a heteroskedastic generalized extreme value model (Het-GEV) with overlapping choice sets. Studying the Greater Toronto and Hamilton Area (GTHA), models are estimated using Revealed Preference (RP) household travel data from the 2006 Transportation Tomorrow Survey (TTS). Empirical models are used to evaluate dynamic transit and road pricing policies. Results indicate that the models are capable of capturing mode and time switching behaviour in response to peak pricing policies. To alleviate demand while maintaining transit mode share, a road charge and a moderate, flat, transit fare increase throughout the morning peak are recommended.
50

An Investigation into the Flexural Behaviour of GFRP Reinforced Concrete Beams

Getzlaf, Douglas Donald 20 November 2012 (has links)
Non-corroding materials, such as Fibre-Reinforced Polymer (FRP) bars, are now being used as reinforcement for reinforced concrete structures in order to extend their lifetime and minimize maintenance costs. Because of the softer and brittle behaviour of GFRP bars, behaviour of structural members reinforced with this material is different than that of steel-reinforced members. In this study, 16 GFRP reinforced beams were constructed and tested under flexure and shear loads to failure. Effects of different variables, such as amount of longitudinal and lateral reinforcements, type of bars and concrete strength, were investigated for their effects. The flexural provisions of design codes, namely CSA S806-12, CSA S6-06, and report ACI 440.1R-06, were evaluated against the test data. The main provisions investigated are failure modes, ultimate strength, moment-curvature response, deflection, crack widths, and deformability.

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