Engineering Commons^™

Testing And Modeling Of The Thixotropic Behavior Of Cementitious Materials., Bashir Hasanzadeh

Electronic Theses and Dissertations

During construction, concrete goes under various operations. It is normally transported to the job site, be placed and consolidated in the formwork, etc. The easiness and quality of these operations are very much related to the intrinsic rheological properties of concrete. Therefore, a good understanding of rheological behavior of concrete under various conditions are needed. Thixotropy is an important part of rheology. The thixotropic behaviors of concrete can be good representatives of its flow behaviors on the job site. For example, the breakdown aspect of thixotropy can help to explain how its flow behavior can impact concrete pumping and its …

Transformation Of Nonlinear Waves In The Presence Of Wind, Current, And Vegetation, Haifei Chen

Electronic Theses and Dissertations

Accurate prediction of extreme wave events is crucial for the safe maritime activities and offshore operations. Improved knowledge of wave dissipation mechanisms due to breaking and vegetation leads to accurate wave forecast, protecting life and property along the coast. The scope of the thesis is to examine the wave transformations in the presence of wind, current, and vegetation, using a two-phase flow solver based on the open-source platform OpenFOAM. The Reynolds-Averaged Navier-Stokes (RANS) equations are coupled with a Volume of Fluid (VOF) surface capturing scheme and a turbulence closure model. This RANS-VOF model is adapted to develop a numerical wind-wave-current …

The Macro-Modelling Of Steel Fiber Reinforced Concrete/Mortar Flexural Tensile Behavior And Mix Optimization For Flexural Strength., Li Liu

Electronic Theses and Dissertations

With the continuous advances in materials’ technology, the performance of the commonly used concrete building material has continued to improve. Compressive strengths exceeding 75 MPa are now being used in applications throughout the world. However, the concrete becomes less ductile and more susceptible to sudden failures with increases in its compressive strength. Although the behavior of concrete is generally governed by its compressive strength, its tensile strength, although much lower, is also important. This tensile strength impacts appearance, the serviceability and durability of concrete elements. In addition, minimum levels of tensile strength are required for many concrete applications including, earthquake …

Feasibility Of Using 3d Printed Molds For Thermoforming Thermoplastic Composites, Sunil Bhandari

Electronic Theses and Dissertations

This thesis presents a novel combined experimental and numerical mechanics approach for characterizing 3D printed thermoplastic materials by the fused deposition modeling process for thermoforming thermoplastic composites. The implications of this work are:

1. a methodology for model-based performance evaluation of 3D printed structural parts, and
2. an improved design of 3D printed molds for composites manufacturing, which has potential for material innovations and scaled-up applications in additive manufacturing.

The thesis formulates basic criteria for selection of thermoplastic polymer used for the 3D printed mold based on forming temperatures. The thesis creates a lattice and shell finite element model of the 3D …

A Tool To Evaluate Sustainability Of Pavement Maintenance Projects., Yibo Zhang

Electronic Theses and Dissertations

Pavement maintenance activities are widely regarded to be critical elements during pavement life cycle, different maintenance techniques have been used to restore or extend the service lives of pavements. However, the existing maintenance practices on pavement system have problems that impair the economic benefits, disturb the natural environment, and somewhat ignore the needs from stakeholders. To minimize these negative impacts, sustainability is an ideal way because it addresses the problems under Triple Bottom Line (TBL, refers to economy, environment, and society). Sustainability analysis within transportation or pavement industry has been studied in different countries, but the concept of sustainable pavement …

Analysis Of Pedestrian Crash Characteristics And Contributing Causes In Central Florida, Zainb Bianco

Electronic Theses and Dissertations

This research investigates the main reasons leading the State of Florida to be ranked among the worst states in terms of pedestrian safety with four metro areas considered the most dangerous for pedestrians among all the United States as reported in the Dangerous by Design report. The study analyzes the characteristics and contributing causes of pedestrian crashes that occurred in Central Florida over a 5 year-period (2011-2015) at intersections and along roadway segments at mid-block locations using the data obtained from the Signal 4 Analytics database. All pedestrian related crashes were compiled and all the 6,789 crash reports were studied …

Water And Energy Costs Of Landfilled Food Waste, Tonmoy Sarker

Electronic Theses and Dissertations

Energy and water are consumed or contaminated during both the production and disposal of wasted food. To date, evaluations of water and energy resources associated with food waste have considered only resources used in food production. To allow for the full characterization of food waste within a Food Energy Water (FEW) nexus framework, this study addresses a fundamental knowledge gap related to the energy and water impacts of food waste after disposal. Fluxes of water and energy related to disposal of wasted food in landfills within the state of Florida were characterized. It is estimated that each metric ton (Mg) …

Hydro-Thermo-Mechanical Behavior Of Concrete At Elevated Temperatures, Manar Al Fadul

Electronic Theses and Dissertations

In the light of recent tragic events, such as, natural disasters, arson and terrorism, studying the thermo mechanical behavior of concrete at elevated temperatures has become of special concern. In addition, the fact that concrete has been widely used as a structural material in many critical applications, such as high rise buildings, pressure vessels, and nuclear plants, enhances the potential risk of exposing concrete to high temperatures. Accordingly, the potential damage to large-scale structures during the course of the fire, besides the possible loss of human life, emphasizes the necessity to better understand the thermo-structural behavior and failure mechanism of …

Hydrologic Controls On The Natural Drainage Networks Extracted From High-Resolution Topographic Data, Milad Hooshyar

Electronic Theses and Dissertations

Drainage networks are important geomorphologic and hydrologic features which significantly control runoff generation. Drainage networks are composed of unchannelized valleys and channels. At valley heads, flow changes from unconfined sheet flow on the hillslope to confined flow in valley. Localized confined flow dominates in valleys as a result of convergent topography with positive curvature. Channels initiate at some distance down from the valley head, and the transition from unchannelized valley to channel is referred to as the channel head. Channel heads occur at a point where fluvial transport dominates over diffusive transport. From the hydrologic perspective, channels are categorized as …

Site Specific Sinkhole Risk Assessment In Central Florida Using Cone Penetrometer Testing, Ryan Shamet

Electronic Theses and Dissertations

As Florida's population is expanding and greater fluctuations in groundwater levels are being recorded, Central Florida has been experiencing a higher frequency of sinkhole occurrences than ever before in recorded history. Sinkholes in Central Florida are formed by a combination of bedrock weathering and overburden soil erosion due to the groundwater recharge and are a part of Florida's past and future geology. The initial stage of a sinkhole is referred to as soil raveling and is the most effective time to perform soil improvement measures, such as grouting, to mitigate further expansion of a subterranean void. Subsurface exploration tests, commonly …

Ichetucknee Springs: Measuring The Effects Of Visitors On Water Quality Parameters Through Continuous Monitoring., Sarah Faraji

Electronic Theses and Dissertations

Ichetucknee Springs System is in north central Florida, under the jurisdiction of the Suwannee River Water Management District (SRWMD). The Ichetucknee River is one of the most pristine spring-fed rivers in Florida and became a state park in 1970. Over 400,000 people visited the Ichetucknee Springs State Park in 2016. From that total, over 130,000 people came during the tubing season alone (Memorial Day to Labor Day). During the tubing season, only 750 visitors per day are allowed to launch from the North Launch, near the Ichetucknee Head Spring. The park enforces visitor usage of the river during these time …

Developing Warrants For Designing Continuous Flow Intersection And Diverging Diamond Interchange, Meshal Almoshaogeh

Electronic Theses and Dissertations

The main goal of this dissertation is to have better understanding of design and operation of the Continuous Flow Intersection (CFI) and Diverging Diamond Interchange (DDI) - as well as numerous factors that affect signalized intersection and interchange performance due to increased left-turn demand. The dissertation attempts to assess the need and justification to redesign intersections and interchanges to improve their efficiency. And to that end, an extensive literature review of existing studies was done with the prime aim of perceiving the principles of these innovative designs and determining the methodology to-be-followed, in order to reach the study's core. Accordingly, …

Groundwater Modeling For Assessing The Impacts Of Natural Hazards In East-Central Florida, Han Xiao

Electronic Theses and Dissertations

In coastal east-central Florida (ECF) , the low-lying coastal alluvial plains and barrier islands have a high risk of being inundated by seawater due to climate change effects such as sea-level rise, changing rainfall patterns, and intensified storm surge from hurricanes., This will produce saltwater intrusion into the coastal aquifer from infiltration of overtopping saltwater. In the inland ECF region, sinkhole occurrence is recognized as the primary geologic hazard causing massive financial losses to society in the past several decades. The objectives of this dissertation are to: (1) evaluate the impacts of sea-level rise and intensified storm surge on the …

Shifted Plastic Hinge Column Connections Using Grouted Sleeves For Accelerated Bridge Construction, Haider Al-Jelawy

Electronic Theses and Dissertations

Accelerated bridge construction (ABC) is being increasingly used in new bridge construction and repair. ABC typically requires prefabricated elements joined with mechanical couplers. Grouted sleeves (GSs) offer good construction tolerances and load transfer between precast elements. However, previous research identified some performance issues with precast columns employing GS connections for seismic regions. Therefore, there is a need to develop improved connection details. This research consists of three components; testing of six large-scale precast reinforced concrete column models, a series of individual component tests on GS bar splices, and analytical studies. Large-scale, precast column models were designed and experimentally tested using …

An Analytical Investigation Of Prestressed Beam Bridge Performance Before And After Widening, Chris Oriordan Adjah

Electronic Theses and Dissertations

As traffic and congestion increase, so does the likelihood of collisions. The solution to this problem is usually through a rehabilitation process with two primary options: (1) widening/expansion of existing roadway and bridges and (2) complete replacement (new construction) of roadway and bridges. The first option is the most feasible and cost-effective. While roadway widening/expansion pose minimal issues, the same cannot be said of bridge widening. An existing bridge presents a multitude of challenges during the planning and design phases, during construction, and throughout the structure's service life. Special attention is required in both the design and detailing of the …

Investigating And Modeling The Impacts Of Illegal U-Turn Violations At Medials Located On Florida's Limited Access Highways, Omar Al-Sahili

Electronic Theses and Dissertations

Illegal U-turn violations are considered part of the Wrong-Way Driving (WWD) maneuvers that could result in head-on crashes and severe injuries, which are often severe because of the high speed of the approaching traffic and limited time to avoid such crash. Therefore, reviewing this type of violation and understanding the contributing factors that may lead drivers to commit such illegal maneuver would help officials foresee and consequently minimize the potential risks that could lead to WWD crashes. The purpose of this thesis is to investigate the illegal U-turn maneuvers on limited access facilities and find the significant contributing factors that …

Field Evaluation Of Insync Adaptive Traffic Signal Control System In Multiple Environments Using Multiple Approaches, Md Shafikul Islam Shafik

Electronic Theses and Dissertations

Since the beginning of signalization of intersections, the management of traffic congestion is one of most critical challenges specifically for the city and urbanized area. Almost all the municipal agencies struggle to manage the perplexities associated with traffic congestion or signal control. The Adaptive Traffic Control System (ATCS), an advanced and major technological component of the Intelligent Transportation Systems (ITS) is considered the most dynamic and real-time traffic management technology and has potential to effectively manage rapidly varying traffic flow relative to the current state-of-the-art traffic management practices. InSync ATCS is deployed in multiple states throughout the US and expanding …

Improving Safety Under Reduced Visibility Based On Multiple Countermeasures And Approaches Including Connected Vehicles, Yina Wu

Electronic Theses and Dissertations

The effect of low visibility on both crash occurrence and severity is a major concern in the traffic safety field. Different approaches were utilized in this research to analyze the effects of fog on traffic safety and evaluate the effectiveness of different fog countermeasures. First, a "Crash Risk Increase Indicator (CRII)" was proposed to explore the differences of crash risk between fog and clear conditions. A binary logistic regression model was applied to link the increase of crash risk with traffic flow characteristics. Second, a new algorithm was proposed to evaluate the rear-end crash risk under fog conditions. Logistic and …

Load Estimation, Structural Identification And Human Comfort Assessment Of Flexible Structures, Ozan Celik

Electronic Theses and Dissertations

Stadiums, pedestrian bridges, dance floors, and concert halls are distinct from other civil engineering structures due to several challenges in their design and dynamic behavior. These challenges originate from the flexible inherent nature of these structures coupled with human interactions in the form of loading. The investigations in past literature on this topic clearly state that the design of flexible structures can be improved with better load modeling strategies acquired with reliable load quantification, a deeper understanding of structural response, generation of simple and efficient human-structure interaction models and new measurement and assessment criteria for acceptable vibration levels. In contribution …

Evaluation Of Woodchip Bioreactor Denitrification Kinetics, Abdoul Aziz Kouanda

Electronic Theses and Dissertations

Agricultural subsurface drainage is a water management practice used to remove excess water in poorly drained soil. The use of fertilizers combined with subsurface drainage practice affects negatively surface water quality due to nutrient loss. Woodchip bioreactors have previously been used as a technology for removing nitrate from agricultural subsurface drainage. Understanding the mechanism that governs nitrate removal in woodchip bioreactors is crucial for field bioreactor design and application. The objective of this project is to determine woodchip bioreactor denitrification kinetics parameters under different operating conditions including hydraulic retention time, temperature and influent nitrate concentrations. Laboratory column experiments were conducted …

The Effectiveness Of Child Restraint And Bicycle Helmet Policies To Improve Road Safety, Claudia Bustamante

Electronic Theses and Dissertations

Analyzing the effect of legislation in children's safety when they travel as motor-vehicle passengers and bicycle riders can allow us to evaluate the effectiveness in transportation policies. The Child Restraint Laws (CRL) and Bicycle Helmet Laws (BHL) were studied by analyzing the nationwide Fatality Analysis Reporting System (FARS) to estimate the fatality reduction as well as drivers' decisions to use Child Restraint Systems (CRS) and bicycle helmets respectively. Differences in legislation could have different effects on traffic fatalities. Therefore, this study presents multiple methodologies to study these effects. In the evaluation of traffic safety issues, several proven statistical models have …

Physical Hydrogeological Modeling Of Florida's Sinkhole Hazard, Adam Perez

Electronic Theses and Dissertations

Sinkholes are one of the major geohazards in karst terrain and pose a social, economic, and environmental risk. In Florida, sinkhole-related insurance claims between 2006 and the third quarter of 2010 amounted to $1.4 billion. Approximately 20 % of the United States is underlain by karst terrain formed from the dissolution of soluble rocks and is susceptible to a sinkhole hazard. Particularly, Texas, Florida, Tennessee, Alabama, Missouri, Kentucky, and Pennsylvania are known as sinkhole states. The scope of this study is to develop a physical model to simulate sinkholes (referred to as a sinkhole simulator), which can assess the qualitative …

Integrating The Macroscopic And Microscopic Traffic Safety Analysis Using Hierarchical Models, Qing Cai

Electronic Theses and Dissertations

Crash frequency analysis is a crucial tool to investigate traffic safety problems. With the objective of revealing hazardous factors which would affect crash occurrence, crash frequency analysis has been undertaken at the macroscopic and microscopic levels. At the macroscopic level, crashes from a spatial aggregation (such as traffic analysis zone or county) are considered to quantify the impacts of socioeconomic and demographic characteristics, transportation demand and network attributes so as to provide countermeasures from a planning perspective. On the other hand, the microscopic crashes on a segment or intersection are analyzed to identify the influence of geometric design, lighting and …

Analysis Of Pedestrian Safety Using Micro-Simulation And Driving Simulator, Jiawei Wu

Electronic Theses and Dissertations

In recent years, traffic agencies have begun to place emphasis on the importance of pedestrian safety. In the United States, nearly 70,000 pedestrians were reported injured in 2015. Although the number only account for 3% of all the people injured in traffic crashes, the number of pedestrian fatalities is still around 15% of total traffic fatalities. Furthermore, the state of Florida has consistently ranked as one of the worst states in terms of pedestrian crashes, injuries and fatalities. Therefore, it is befitting to focus on the pedestrian safety. This dissertation mainly focused on pedestrian safety at both midblock crossings and …

Wrong-Way Driving: A Regional Approach To A Regional Problem, Md. Omar Faruk

Electronic Theses and Dissertations

Wrong-way driving (WWD) has been problematic on United States highways for decades despite its rare occurrence. Since WWD crashes are rare, recent researchers have studied WWD non-crash events such as WWD 911 calls and WWD citations to understand the overall nature and trend of WWD. This paper demonstrates the regional nature of the WWD problem and proposes regional transportation systems management and operations (Regional TSM&O) solutions to combat this problem. Specifically, it was found that 11% of all WWD multi-data events (e.g., multiple 911 calls for the same WWD event) traveled from one county to another. Additionally, 30% of all …

A Case Study Of Student Veteran Efficacy In The College Of Engineering And Information Technology At Georgia Southern University, Kevin G. Finley

Electronic Theses and Dissertations

This thesis addresses the issues student veterans face in their transition from military to academic life while pursuing an undergraduate degree in the STEM fields (Science, Technology, Engineering, Math) at Georgia Southern University’s College of Engineering and Information Technology (CEIT). Historically this transition has been a difficult one. Through the implementation of a mentorship program comprised of military veterans on the staff and faculty of Georgia Southern University as well as assistance and participation from members of the case study researcher team and primary researcher this program assisted incoming military student veterans as they assimilated into the collegiate atmosphere. The …

Polyurethane Fiber Reinforced Polymer Strengthening Of Shear Deficient Reinforced Concrete Beams, Yasir Al-Lebban

Electronic Theses and Dissertations

The use of externally-bonded fiber-reinforced polymer (FRP) composites has been established as an effective means for the strengthening of shear-deficient reinforced concrete (RC) flexural members. Epoxy-based wet layup systems were predominantly employed in previous studies. In this study, carbon FRP pre-impregnated with polyurethane resin is utilized in strengthening shear-deficient RC beams and compared to an epoxy resin. Fourteen small-scale (96 in span, 6 in width, and 12 in height) and five large-scale (132 in span, 12 in width, and 17 in height) flexural specimens were tested, considering FRP system type (polyurethane versus epoxy), size effect, shear span-to-depth ratio, FRP configuration …

Effect Of Load Path And Failure Modes On Seismic Response Of Regular Bridges., Haider Darwash

Electronic Theses and Dissertations

Bridges are essential infrastructure constituents that have been studied for centuries. Typically, seismic bridge design and assessment utilize simplified modeling and analysis techniques based on one-dimensional spine elements and zero-length springs/hinges. The geometry of the elements and calibration of parameters are based on assumptions for the lateral load path and failure modes, e.g., sacrificial backwall and shear keys, neglecting wing walls, and strength based on backfill alone. These assumptions have led to observations of underestimated resistance, overestimated displacement demands, and unpredicted damage and failure mode. The focus of the study is on ordinary standard bridges with continuous reinforced concrete box …

Annual Water Balance Model Based On Generalized Proportionality Relationship And Its Applications, Yin Tang

Electronic Theses and Dissertations

The main goal of this dissertation research is to derive a type of conceptual models for annual water balance at the watershed scale. The proportionality relationship from the Soil Conservation Service Curve Number method was generalized to annual scale for deriving annual water balance model. As a result, a one-parameter Budyko equation was derived based on one-stage partitioning; and a four-parameter Budyko equation was derived based on two-stage partitioning. The derived equations balance model parsimony and representation of dominant hydrologic processes, and provide a new framework to disentangle the roles of climate variability, vegetation, soil and topography on long-term water …

A Comprehensive Assessment Of Vehicle-To-Grid Systems And Their Impact To The Sustainability Of Current Energy And Water Nexus, Yang Zhao

Electronic Theses and Dissertations

This dissertation aims to explore the feasibility of incorporating electric vehicles into the electric power grid and develop a comprehensive assessment framework to predict and evaluate the life cycle environmental, economic and social impact of the integration of Vehicle-to-Grid systems and the transportation-water-energy nexus. Based on the fact that electric vehicles of different classes have been widely adopted by both fleet operators and individual car owners, the following questions are investigated: 1. Will the life cycle environmental impacts due to vehicle operation be reduced? 2. Will the implementation of Vehicle-to-Grid systems bring environmental and economic benefits? 3. Will there be …