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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.
91

Towards Simplified Tools for Analysis of Reinforced Concrete Structures Subjected to Impact and Impulsive Loading: A Preliminary Investigation

Trommels, Heather 17 July 2013 (has links)
The analysis of reinforced concrete structures under blast and impact loads is an area of research that has become increasingly relevant in recent years. Complex hydrocodes are typically used for impact analyses, although single-degree-of-freedom methods have also been developed. There are a number of disadvantages associated with both methods, and the Canadian Nuclear Safety Commission (CNSC) is looking for a tool that can be used in conjunction with hydrocodes to analyze hard and soft missile impacts, with target damage ranging from flexural cracking to perforation. The VecTor programs, a suite of nonlinear finite element programs developed at the University of Toronto for the analysis of reinforced concrete structures, can potentially be developed into such tools. The analytical work done in this study serves to investigate the current impact and impulse loading analysis capabilities in VecTor2 and VecTor3, and to identify areas where work should be focused in the future.
92

Metakaolin Effects on Concrete Durability

Zeljkovic, J. Michael 18 February 2010 (has links)
Partial replacement of cement by metakaolin is known to improve concrete durability, by refining the pore structure to improve fluid transport properties and by reducing the alkalinity of the pore solution to make ASR less problematic. A gap exists in the literature as to the salt scaling performance and magnesium sulphate performance of metakaolin concrete. 10 concrete mixes were cast at w/cm ratios of 0.4 and 0.5. In addition to metakaolin, grade 80 slag was used as well as CSA GU cement. All replacement levels were tested for setting properties, compressive strength, drying shrinkage, sulphate resistance, salt scaling, ASR mitigation and chloride diffusion characteristics according to the appropriate CSA and ASTM standards. It was found that metakaolin showed better performance in magnesium sulphate solutions than slag and that metakaolin concretes attained strength and other durability properties much faster than mixes without it. Keywords: metakaolin, ASR, sulphate, magnesium, scaling, setting, diffusion
93

Framework for the Integration of a Parameterized Logit Captivity Model for Morning Commuting in the Greater Toronto and Hamilton Area with an Agent Based Dynamic Traffic Micro Simulation

Weiss, Adam 11 December 2013 (has links)
This thesis proposes a framework that combines a mode choice model with a large scaled agent-based multimodal traffic microsimulation. Both components are discussed with respect to their development as separate entities. The mode choice model uses a formulation that explicitly considers latent modal captivity despite using conventional travel survey data. An existing multimodal microsimulation traffic assignment model used in the study area is enhanced and partially calibrated for use with the MATSIM traffic assignment tool. Both of the components are then tested independently in terms of statistical and behavioral validity and a conceptual procedure to test the implications of the mode choice model on mode switching behaviour within the traffic assignment model is presented. Other applications of both the travel assignment model and mode choice model are discussed. In order for the framework to become operational, further development with respect to the traffic assignment model is required.
94

A Microsimulated Industrial and Occupation-based Labour Market Model for Use in the Integrated Land Use, Transportation, Environment (ILUTE) Modelling System

Harmon, Adam 27 November 2013 (has links)
Urban microsimulators have been increasingly used to forecast land use, environmental and transportation conditions in cities and are a major tool for stakeholders to analyze the effects of urban policy. Although demographic and residential land use models have been well developed for the majority of these systems, labour market conditions and the forecasting of future jobs have at best been limited to high-level exogenous processes. This thesis aims to develop and implement a truly endogenous job supply and job matching model for use with the Integrated Land Use, Transportation, Environment (ILUTE) modelling system. Jobs within the system are tracked individually at both the occupational and industrial level, and matching occurs within an open market framework in an effort to simulate the true macroeconomic conditions of the real world.
95

Metakaolin Effects on Concrete Durability

Zeljkovic, J. Michael 18 February 2010 (has links)
Partial replacement of cement by metakaolin is known to improve concrete durability, by refining the pore structure to improve fluid transport properties and by reducing the alkalinity of the pore solution to make ASR less problematic. A gap exists in the literature as to the salt scaling performance and magnesium sulphate performance of metakaolin concrete. 10 concrete mixes were cast at w/cm ratios of 0.4 and 0.5. In addition to metakaolin, grade 80 slag was used as well as CSA GU cement. All replacement levels were tested for setting properties, compressive strength, drying shrinkage, sulphate resistance, salt scaling, ASR mitigation and chloride diffusion characteristics according to the appropriate CSA and ASTM standards. It was found that metakaolin showed better performance in magnesium sulphate solutions than slag and that metakaolin concretes attained strength and other durability properties much faster than mixes without it. Keywords: metakaolin, ASR, sulphate, magnesium, scaling, setting, diffusion
96

A Microsimulated Industrial and Occupation-based Labour Market Model for Use in the Integrated Land Use, Transportation, Environment (ILUTE) Modelling System

Harmon, Adam 27 November 2013 (has links)
Urban microsimulators have been increasingly used to forecast land use, environmental and transportation conditions in cities and are a major tool for stakeholders to analyze the effects of urban policy. Although demographic and residential land use models have been well developed for the majority of these systems, labour market conditions and the forecasting of future jobs have at best been limited to high-level exogenous processes. This thesis aims to develop and implement a truly endogenous job supply and job matching model for use with the Integrated Land Use, Transportation, Environment (ILUTE) modelling system. Jobs within the system are tracked individually at both the occupational and industrial level, and matching occurs within an open market framework in an effort to simulate the true macroeconomic conditions of the real world.
97

Controlling Early-age Transverse Cracking in High Performance Concrete Bridge Decks

Liu, Eric Ying Xian 04 December 2013 (has links)
This research was undertaken to study the effects of high performance concrete (HPC) mix design modifications on the propensity of early-age cracking. Seven mixtures were tested: one 35 MPa conventional concrete (CC) mixture made with ordinary Portland cement with blended slag; one typical 50 MPa HPC mixture containing slag and silica fume; and five modified HPC mixtures using extra set-retarder, increased slag replacement, shrinkage-reducing admixture (SRA), pre-saturated lightweight aggregate (LWA), and decreased cement paste content to improve thermal and/or shrinkage properties. The mixtures were tested for durability, mechanical, thermal, and shrinkage properties. All modified HPC mixtures showed reduced shrinkage relative to the HPC control mixture, and the most shrinkage mitigation was observed in the mixture containing LWA. While SRA reduced restrained shrinkage in HPC to the magnitude of CC, it provided very low rapid chloride penetrability, and using LWA in HPC resulted in significant restrained shrinkage reduction compared to CC.
98

Controlling Early-age Transverse Cracking in High Performance Concrete Bridge Decks

Liu, Eric Ying Xian 04 December 2013 (has links)
This research was undertaken to study the effects of high performance concrete (HPC) mix design modifications on the propensity of early-age cracking. Seven mixtures were tested: one 35 MPa conventional concrete (CC) mixture made with ordinary Portland cement with blended slag; one typical 50 MPa HPC mixture containing slag and silica fume; and five modified HPC mixtures using extra set-retarder, increased slag replacement, shrinkage-reducing admixture (SRA), pre-saturated lightweight aggregate (LWA), and decreased cement paste content to improve thermal and/or shrinkage properties. The mixtures were tested for durability, mechanical, thermal, and shrinkage properties. All modified HPC mixtures showed reduced shrinkage relative to the HPC control mixture, and the most shrinkage mitigation was observed in the mixture containing LWA. While SRA reduced restrained shrinkage in HPC to the magnitude of CC, it provided very low rapid chloride penetrability, and using LWA in HPC resulted in significant restrained shrinkage reduction compared to CC.
99

Framework for the Integration of a Parameterized Logit Captivity Model for Morning Commuting in the Greater Toronto and Hamilton Area with an Agent Based Dynamic Traffic Micro Simulation

Weiss, Adam 11 December 2013 (has links)
This thesis proposes a framework that combines a mode choice model with a large scaled agent-based multimodal traffic microsimulation. Both components are discussed with respect to their development as separate entities. The mode choice model uses a formulation that explicitly considers latent modal captivity despite using conventional travel survey data. An existing multimodal microsimulation traffic assignment model used in the study area is enhanced and partially calibrated for use with the MATSIM traffic assignment tool. Both of the components are then tested independently in terms of statistical and behavioral validity and a conceptual procedure to test the implications of the mode choice model on mode switching behaviour within the traffic assignment model is presented. Other applications of both the travel assignment model and mode choice model are discussed. In order for the framework to become operational, further development with respect to the traffic assignment model is required.
100

The Registration and Segmentation of Heterogeneous Laser Scanning Data

Al-Durgham, Mohannad M. 15 July 2014 (has links)
Light Detection And Ranging (LiDAR) mapping has been emerging over the past few years as a mainstream tool for the dense acquisition of three dimensional point data. Besides the conventional mapping missions, LiDAR systems have proven to be very useful for a wide spectrum of applications such as forestry, structural deformation analysis, urban mapping, and reverse engineering. The wide application scope of LiDAR lead to the development of many laser scanning technologies that are mountable on multiple platforms (i.e., airborne, mobile terrestrial, and tripod mounted), this caused variations in the characteristics and quality of the generated point clouds. As a result of the increased popularity and diversity of laser scanners, one should address the heterogeneous LiDAR data post processing (i.e., registration and segmentation) problems adequately. Current LiDAR integration techniques do not take into account the varying nature of laser scans originating from various platforms. In this dissertation, the author proposes a methodology designed particularly for the registration and segmentation of heterogeneous LiDAR data. A data characterization and filtering step is proposed to populate the points’ attributes and remove non-planar LiDAR points. Then, a modified version of the Iterative Closest Point (ICP), denoted by the Iterative Closest Projected Point (ICPP) is designed for the registration of heterogeneous scans to remove any misalignments between overlapping strips. Next, a region-growing-based heterogeneous segmentation algorithm is developed to ensure the proper extraction of planar segments from the point clouds. Validation experiments show that the proposed heterogeneous registration can successfully align airborne and terrestrial datasets despite the great differences in their point density and their noise level. In addition, similar testes have been conducted to examine the heterogeneous segmentation and it is shown that one is able to identify common planar features in airborne and terrestrial data without resampling or manipulating the data in any way. The work presented in this dissertation provides a framework for the registration and segmentation of airborne and terrestrial laser scans which has a positive impact on the completeness of the scanned feature. Therefore, the derived products from these point clouds have higher accuracy as seen in the full manuscript.

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