Engineering Commons^™

Rural To Urban Intercity Transit User Characteristics Analysis, Demand Estimation And Network Design, Hongtai Yang

Doctoral Dissertations

Rural transit always plays a critical role in transporting rural residents, especially the ones who do not have a car, cannot drive, or choose not to drive. Intercity bus (ICB), deviated fixed route transit (DFRT) and demand responsive transit (DRT) are three major modes of rural public transportation. Although there are more DFRT and DRT service providers and services in the US, due to institutional issues, there are much more studies about ICB than DFRT and DRT. Meanwhile, state governments are struggling on how to improve the rural transit system with limited budget. This dissertation is aimed to fill the …

Bond Performance Of High-Capacity Strands In High Strength Concrete, Xin Jiang

Doctoral Dissertations

18-mm-diameter (0.7-in.) strand has the ability to introduce almost twice the prestressing force of 13-mm-diameter (0.5-in.) strand and 135% of the prestressing force of 15-mm-diameter (0.6-in.) strand, which could result in a significant increase in the span capacity of the current AASHTO bulb tee girders without having to modify the sections or acquire new forms. To date, the information regarding the bond performance of 18-mm-diameter (0.7-in.) prestressing strand is very limited, preventing its application despite its attractive high-strength. Also, our understanding of the bond mechanism is incomplete and non-quantitative; a rational understanding of the bond mechanism would help predict the …

Bedload Transport Sampling, Characterization And Modeling On A Southern Appalachian Ridge And Valley Stream, Patrick Lasater Mcmahon

Doctoral Dissertations

Estimates of bedload transport rates developed from existing transport models are notoriously inaccurate(Wilcock 2001). The gravel bed models addressed in this study include the Meyer-Peter and Muller; Parker, Klingeman, and McLean; and Wilcock two-fraction models. The question of whether or not these models predict bedload transport rates in a Southern Appalachian Ridge and Valley stream is complicated by the fact that these models have only been previously assessed in terms of their agreement with bedload transport rates measured in the Western regions of the U.S. Further, due to the strongly non-linear form of bedload transport models discrete errors and cumulative …

Effects Of Data Resolution And Human Behavior On Large Scale Evacuation Simulations, Wei Lu

Doctoral Dissertations

Traffic Analysis Zones (TAZ) based macroscopic simulation studies are mostly applied in evacuation planning and operation areas. The large size in TAZ and aggregated information of macroscopic simulation underestimate the real evacuation performance. To take advantage of the high resolution demographic data LandScan USA (the zone size is much smaller than TAZ) and agent-based microscopic traffic simulation models, many new problems appeared and novel solutions are needed. A series of studies are conducted using LandScan USA Population Cells (LPC) data for evacuation assignments with different network configurations, travel demand models, and travelers’ compliance behavior.

First, a new Multiple-Source-Nearest-Destination Shortest Path …

Investigation Of Asphalt Pavement Mixture Blending Utilizing Analytical Chemistry Techniques, Benjamin Frank Bowers

Doctoral Dissertations

The use of Reclaimed Asphalt Pavement (RAP) in new pavement mixtures is a topic of interest throughout the transportation industry and academia due its economic and environmental implications. There is concern however about how well the binder from the RAP blends with new, virgin binder when the mixture is created. Insufficient blending of the aged and unaged binders may compromise the long-term pavement performance. In this study, an enhanced staged extraction method is coupled with two chemical testing techniques to develop a novel approach for evaluating blending efficiency from a qualitative and quantitative perspective: Gel Permeation Chromatography (GPC) and Fourier …

Investigation Of Composite Patch Performance Under Low-Velocity Impact Loading, Geoffrey Roy Goodmiller

Masters Theses

Bonded fiber composite repair on damaged metal structures can be an effective method to restore load carrying capacity or increase damage resistance. Low velocity impacts can cause barely visible damage to the interior structure of laminated composites. Delamination between plies is of particular concern in these composites. Impacts may also create disbonds between the patch and metal substrate. A building-block approach was suggested to model impact damage to composite patches. Composite, adhesive, and metal substrate damage models were separately validated and then combined. Cohesive Zone theory modeled interlaminar composite damage and adhesive damage. Hashin failure criteria with energy dissipation based …

A Framework To Predict High Risk Roadways For Pedestrians In Tennessee, Zane Hunter Pannell

Masters Theses

Pedestrians and bicyclists are a class of vulnerable road users that are often over-represented in incapacitating injury or fatal crash statistics. Because non-motorized trips are vital to many urban and rural residents for utility or recreation and exercise, it is essential to identify safety deficiencies in our existing transportation infrastructure to address rising injuries and fatalities among this group of road users. As the economy continues to struggle and fuel prices remain high, many cities and rural transportation agencies are seeing large increases in bicycling, walking, and transit ridership. While passenger car fatalities have shown sharp declines in the last …

An Automated Finite Element Analysis Framework For The Probabilistic Evaluation Of Composite Lamina Properties, Jonathan Phillips Weigand

Masters Theses

This thesis outlines the development of computational modeling tools used to predict the elastic properties of composite lamina from representative volume elements (RVE) using numerical methods. The homogenization approach involves the use of Gauss’s Theorem to simply the average volumetric strain integral into a surface integral containing which is defined by surface displacements and their direction. Simulations of RVEs under specific loading conditions (longitudinal tension or shear and transverse tension or shear) are then performed in the software package ABAQUS to obtain the surface displacements. It was found that obtaining quality meshes and applying periodic boundary conditions for each RVE …

Isolation As A Seismic Design Strategy For Bridges In The New Madrid Seismic Zone, Timothy E. Huff

Doctoral Dissertations

The seismic hazard in the New Madrid Seismic Zone (NMSZ) is primarily from the New Madrid Fault System (NMFS), which produced a series of large earthquakes in 1811-1812. Estimates of the magnitude of these earthquakes and the event magnitude appropriate for structural design in the New Madrid Seismic Zone vary greatly and have been the subject of much debate.

Current bridge design practice in the region relies primarily upon controlled damage by plastic hinging in columns/piles at piers to prevent collapse. Abutments are typically modeled with linear springs to represent piles and backfill stiffness. The usefulness, after a major seismic …

Evaluating Predictability In The Community Earth System Model In Response To The Eruption Of Mount Pinatubo, Abigail Laurel Gaddis

Doctoral Dissertations

A central goal of climate research is to determine the perceptible effects of climate change on humans; in other words, the regional and decadal scale effects of carbon dioxide forcing. Identifying the most pronounced and long-lasting responses of climate variables to forcing is important for decadal prediction since forcing terms are a source of predictability on those time scales. Powerful volcanic eruptions provide a transient forcing on the climate system, creating a test bed for climate models. In this study, the Mount Pinatubo eruption is simulated in the Community Earth System Model, CESM1.0, for three model configurations: fully coupled T85 …

Investigation Into Key Pavement Materials And Local Calibration On Mepdg, Changjun Zhou

Doctoral Dissertations

The release of Mechanistic-Empirical Pavement Design Guide (MEPDG) in 2004 has been leading a transition from empirically-based pavement design to a mechanical-empirical procedure. The pavement performance prediction models in the MEPDG combines design inputs such as material properties, traffic, and climate to the observed field performance. Since the prediction models were primarily calibrated through inputs and pavement performance data from Long Term Pavement Performance database, local calibrations were highly recommended due to the potential differences between national and local conditions.

Key properties of pavement materials were investigated for the local calibration of the MEPDG, including the coefficient of thermal expansion …

A Comparative Health And Safety Analysis Of Electric-Assist And Regular Bicycles In An On-Campus Bicycle Sharing System., Brian Casey Langford

Doctoral Dissertations

E-bikes have emerged in recent years as a valid mode of transportation. Comparable to regular bicycles in many ways, e-bikes offer some added advantages due to the additional electric motor on the bicycle. This dissertation combines three different research efforts centered on the study of e-bikes and their inclusion in e-bike sharing systems. First, it looks at a model for e-bike sharing at the University of Tennessee and examines system operations, performance, and demand from users. It investigates the characteristics of trips using the sharing system’s fleet of regular and electric bicycles, and it describes the preferences among system users …

Structural Health Monitoring And Damage Identification Of Bridges Using Triaxial Geophones And Time Series Analysis, Reza Vasheghani Farahani

Doctoral Dissertations

This study uses the vibration data of two full-scale bridges, subjected to controlled damage, along the I-40 west, near downtown Knoxville, TN, to evaluate the feasibility of time series-based damage identification techniques for structural health monitoring. The vibration data was acquired for the entrance ramp to James White Parkway from I-40 westbound, and the I-40 westbound bridge over 4th Avenue, before the bridges were demolished during I-40 expansion project called Smartfix40. The vibration data was recorded using an array of triaxial geophones, highly sensitive sensors to record vibrations, in healthy and damaged conditions of the bridges. The vibration data is …

In-Plane Shear Investigation On Masonry Walls, Shane Chandler Morrison

Doctoral Dissertations

Analysis has been performed on approximately 200 shear walls of various masonry types, reinforcement, and grouting scenarios to determine the trends of various wall parameters to strength. The database is assembled from that belonging to researchers over the last 30 years.

Strut-and-tie methods from current concrete codes are employed and new methods proposed to calculate the in-plane shear strength of masonry walls. In addition, a simplified method based upon strut-and-tie methodology is presented to calculate the masonry contribution to the in-plane strength of these walls, with contributions from axial load and horizontal reinforcement based upon past data and efficiency of …

Driver Behavior At Railway-Highway Grade Crossings With Passive Traffic Control: A Driving Simulator Study, Bryan Andre Bartnik

Masters Theses

Research to evaluate driver behavior at railway-highway grade crossings with passive traffic control attempts to find an answer to a much debated subject. This study examines the difference in driver behavior and safety at several different types of passive traffic control at grade crossings utilizing a driving simulator. This project utilized the University of Tennessee’s high fidelity driving simulator to perform a study on passive highway-railway grade crossings. Although the crash rates at grade crossings have decreased in recent years, there is still more work to be done. Safety improvements can be made to both passive and active grade crossings. …

Strength And Deformation Of “Tunable” Clay-Polymer Composites, Matthew David Bishop

Masters Theses

There are many different types of clay that exist throughout the world, and many are characterized by undesirable engineering properties. Soil improvement techniques are often implemented on these soils such as solidification, reinforcement, etc. However, these solutions are a “static” approach, as the soil’s properties cannot be modified over time. The development of the specific clay-polymer composites used in this study was motivated by the idea of creating a geomaterial that could be modified over time by adjusting its fabric, namely in the form of controlling interparticle and interlayer spacings. Therefore, the composites that are used in this study are …

Linkage Between Characteristics Of Premise Plumbing Systems And Microbial Quality Of Stagnant Drinking Water, Joshua Thomas Frerichs

Masters Theses

The length of pipe between the water main and the point of use (POU), known as premise plumbing, has a direct impact on public health. However, relatively little is known about factors that affect the microbial quality in premise plumbing. Although microbial quality typically degrades during stagnation, little research is present linking factors such as building age and level of usage to the extent to which stagnation occurs.

To gain insight into the effect of premise plumbing service age on the level of microbial contamination in stagnant drinking water, water at the POU was analyzed. It was observed with statistical …

Industrial Robustness: Understanding The Mechanism Of Tolerance For The Populus Hydrolysate Tolerant Strain Of Clostridium Thermocellum, Jessica Leigh Linville

Doctoral Dissertations

An industrially robust microorganism that can efficiently degrade and convert lignocellulosic biomass into ethanol and next-generation fuels is required to economically produce future sustainable liquid transportation fuels. The anaerobic, thermophilic, cellulolytic bacterium Clostridium thermocellum is a candidate microorganism for such conversions but it, like many bacteria, is sensitive to potential toxic inhibitors developed in the hydrolysate produced during biomass processing. Microbial processes leading to tolerance of the inhibitory compounds found in the pretreated biomass hydrolysate are likely complex and involve multiple genes. In this study, a 17.5% v/v Populus hydrolysate tolerant mutant strain of C. thermocellum was developed by directed …

Dual-Modality (Neutron And X-Ray) Imaging For Characterization Of Partially Saturated Granular Materials And Flow Through Porous Media, Felix Hoyean Kim

Doctoral Dissertations

Problems involving mechanics of partially saturated soil and physics of flow through porous media are complex and largely unresolved based on using continuum approach. Recent advances in radiation based imaging techniques provide unique access to simultaneously observe continuum scale response while probing corresponding microstructure for developing predictive science and engineering tools in place of phenomenological approach used to date.

Recent developments with X-ray/Synchrotron and neutron imaging techniques provided tools to visualize the interior of soil specimen at pore/grain level. X-ray and neutron radiation often presents complementary contrast for given condensed matter in the images due to different fundamental interaction mechanisms. …

Solid Waste Reduction Practices In The Southeastern United States: Public Perceptions And Proposed Policy Changes, Lauren Ashley Raup-Plummer

Masters Theses

The U.S. Environmental Protection Agency (EPA) has highlighted the municipal solid waste stream as an area of critical interest due to the non-sustainable nature of existing landfilling or “dumping” practices. In addition to traditionally defined municipal solid waste – commonly referred to as garbage or rubbish – materials such as biosolids, a by-product of wastewater treatment, and animal manure also comprise the landfilled waste stream. Currently, disposal options for biosolids waste materials are limited due to regulations imposed by the EPA to protect waterways and coastal environments, and one of the few alternatives for biosolids disposal is land application. Unfortunately, …

Rule High School Athletic Field Renovation, Nathan W. Foust

Chancellor’s Honors Program Projects

No abstract provided.