Engineering Commons^™

On The Fatigue Of Headed Shear Studs In Steel-Concrete Composite Bridge Girders, Brianna Laurene Ovuoba

Graduate Theses and Dissertations

Shear connectors are commonly used in steel bridges to join the concrete deck and steel superstructure, providing a mechanism for shear transfer across the steel-concrete interface. The most common shear connector is the headed shear stud. In the current AASHTO LRFD Bridge Specifications on composite design, shear stud fatigue often governs over static strength, and a large number of shear connectors often result. This dissertation investigates headed shear stud fatigue capacities and demands, and provides insight into conservancies in existing design specifications through examination of existing high-traffic bridge performance.

To investigate stud capacity, a total of six high-cycle fatigue tests …

Investigating Fate Of Silver Nanoparticles In Wastewater Biofilms, Connie Marie Walden

Graduate Theses and Dissertations

As industrial advances make everyday life easier for human kind, the processes by which we need to maintain sanitary conditions for both water and wastewater treatment will become increasingly complex. Innovations in food packaging and textile design incorporate engineered nanoparticles (ENPs) to increase antimicrobial properties of clothing, maintain product color, and keep food in packaging from spoilage. For most products, ENPs released will enter the sanitary sewer system, and ultimately wastewater treatment plants. Biofilms grow universally on surfaces where a protective layer of extracellular polymeric substances (EPS) shields attached cells from stressors. In wastewater treatment, complex biofilms are utilized as …

Cost-Savings Of Implementing Site-Specific Ground Motion Response Analysis In Design Of Mississippi Embayment Bridges, Ethan Ryan Benton Baker

Graduate Theses and Dissertations

Deep dynamic site characterization and a site-specific ground motion response analysis (SSGMRA) were conducted for a bridge site in Monette, Arkansas. The SSGMRA indicated the design acceleration response spectrum determined using the American Association of State Highway and Transportation Officials (AASHTO) general seismic procedure could be reduced by 1/3 for the short period range due to attenuation of the short-period ground motions. The steel girder pile-bent bridge, originally designed using the AASHTO general seismic design procedure, was redesigned using the updated seismic demands estimated from SSGMRA. A cost-savings analysis was then conducted to determine the potential savings associated with conducting …

Development Of An Internal Camera-Based Volume Determination System For Triaxial Testing, Sean Elliott Salazar

Graduate Theses and Dissertations

Accurate measurement of axial, radial, and volumetric strain parameters are critical to the understanding of phase relationships and the constitutive behavior for saturated and unsaturated soils. The use of photographic monitoring techniques for laboratory-based measurement of these parameters have become common. A novel technique that utilized camera instrumentation located within the triaxial testing cell was developed and validated. By placing the instrumentation inside of the cell, instead of the instrumentation being located outside of the cell, the technique eliminated cumbersome corrections required to account for optical distortions due to 1) the refraction of light at the confining fluid-cell wall-atmosphere interfaces, …

Automated Pin-Dot Marking Effects On A709-Gr50 Steel Plate Fatigue Capacity, Michael Andrew Noernberg

Graduate Theses and Dissertations

During fabrication of multi-piece steel bridge assemblies, markings are often made on the steel surface to identify/track individual pieces or to provide reference for fabrication layout or later erection. Automated marking methods such as computer numerically controlled (CNC) pin-dot marking offer fabrication efficiencies; however, for marked steel sections subjected to frequent or repeated loading (i.e. bridge girders) many code specifications require experimental testing to verify any marking effects on fatigue capacity. In this study, the effects of automated pin-dot markings on the fatigue capacity of A709-Gr50 bridge steel are experimentally investigated from 13 specimens considering 2 marking frequencies (corresponding to …

An Evaluation Of Borehole Hydraulic Conductivity Equations And Field Determined Soil Water Characteristic Curves, Johnathan Dale Blanchard

Graduate Theses and Dissertations

The methods utilized to determine the hydraulic conductivity of compacted clay liners (CCLs) are of importance for safe guarding the environment from landfill leachate. Therefore, the methods utilized in the analysis of the Two Stage Borehole (TSB) test, as described in the ASTM D6391-11 (Method A, B, and C) standard, were evaluated. Data from hydraulic conductivity tests, as performed on three test pads, were utilized to review the ASTM D6391-11 equations. Additionally, two test pads were instrumented with volumetric water content and soil water matric potential sensors to facilitate the determination of field-obtained soil water characteristic curves (SWCCs) and hydraulic …

Evaluation Of Water Resources And Hydraulic Influences In The Restoration Of The Western Part Of The Mesopotamian Marshlands, Ali Kareem Al-Quraishi

Graduate Theses and Dissertations

The purpose of this study is to assess the water resources and water conveyance system of the western part of the Mesopotamian marshes (Al-Hammar marsh) as well as develop a water conveyance system to distribute water throughout the western Al-Hammar marsh. These processes are significant to identify the current restoration problems and help to create restoration strategies for the marsh. Also, proper management strategy to the Al-Hammar marsh is necessary to preserve the marsh ecosystem, irrigate lands, and provide domestic necessities in the villages.

The overall project is divided into three main chapters which address the current ecological and hydrological …

Development Of Pre-Stressed Retrofit Strategies For Mitigating Fatigue Cracking In Steel Waterway Lock Gate Components, Christine Michelle Lozano

Graduate Theses and Dissertations

Lock gates are an important part of the transportation infrastructure within the United States (US), having many economic, safety, and environmental benefits over rail and highway transportation systems. Unfortunately, many existing lock gates throughout the US have reached or exceeded their initial design life and require frequent repairs to remain in service. Unscheduled repairs often increase as gates age, having a local economic impact on freight transport which can create economic ripples throughout the nation. Fatigue and corrosion are key causes of unscheduled service interruptions, degrading lock gate components over time. Additionally, because lock gates are submerged during operation, crack …

Dem Study Of A Single Stone Column In A Clayey Stratum, Anibal Enrique Santos

Graduate Theses and Dissertations

Aggregate piers are an alternative ground improvement technique used for improving the bearing capacity and reducing the total and differential settlement of foundations supported on compressible soils. The piers are composed of a series of vibrationally compacted aggregate lifts from a desired depth up to the finished foundation level. The shear strength of the coarse-grained material comprising an aggregate pier is defined by its internal friction angle. There are several factors affecting the friction angle of the granular material that include: confining stress, particle shape, relative density and particle distribution (gradation). These factors are not directly considered in the design …

Systematic Review For Water Network Failure Models And Cases, Yufei Gao

Graduate Theses and Dissertations

As estimated in the American Society of Civil Engineers 2017 report, in the United States, there are approximately 240,000 water main pipe breaks each year. To help estimate pipe breaks and maintenance frequency, a number of physically-based and statistically-based water main failure prediction models have been developed in the last 30 years. Precious review papers focused more on the evolution of failure models rather than modeling results. However, the modeling results of different models applied in case studies are worth reviewing as well.

In this review, we focus on research papers after Year 2008 and collect latest cases without repetition. …

Methodologies For Solving Integrated Transportation And Scheduling Problems, Fereydoun Adbesh

Graduate Theses and Dissertations

This research proposes novel solution techniques to optimize two real-world problems in the area of scheduling and transportation. We first consider a model for optimizing the operations of dredges. In this problem, scheduling and assignment decisions are integrated across a finite planning horizon. Additional constraints and problem elements explicitly considered include, but are not limited, to environmental work window restrictions, budget limitations, dredge operation rates and schedule-dependent dredge availability. Our approach makes use of Constraint Programming (CP) to obtain quality and robust solutions within an amount of time small enough to be useful to practitioners. The expanded feature set of …

Soil-Structure Interaction Effects On The Seismic Response Of Low-Rise Eccentrically Braced Frames, Luis Gerardo Buitrago Goyez

Graduate Theses and Dissertations

The importance of soil-structure interaction (SSI) effects on the seismic response of

buildings has been long recognized and has been researched for over 40 years. However, SSI

analysis has only been applied in a few building projects because the fixed base condition is

considered to provide a conservative estimation for the response of buildings under seismic loads.

This assumption of a fixed base condition adopted by practitioners is not always conservative or

cost-effective, especially for rigid buildings over soft soils. Additionally, for the case of ductile

steel frames with eccentric configurations, the influence of SSI on their seismic performance has …

Laboratory Resistivity Measurements For Soil Characterization, Behdad Mofarraj Kouchaki

Graduate Theses and Dissertations

Field based electrical resistivity measurements, such as electrical resistivity tomography (ERT) and capacitively coupled resistivity (CCR), are geophysical methods that offer a non-destructive and rapid means to collect continuous data. As such, ERT and CCR are becoming increasingly popular tools for geotechnical engineers; however, it is challenging to derive geotechnical information such as soil type, density, and water content from the data. A laboratory geophysical investigation was carried out to gain a better understanding of the parameters that affect the electrical resistivity of soils and devise a relationship between resistivity and soil type or classification. In this study, a soil …

Development Of Deep Site Specific And Reference Shear Wave Velocity Profiles In The Canterbury Plains, New Zealand, Michael Ryan Deschenes

Graduate Theses and Dissertations

Deep (typically >1000 m) shear wave velocity profiles were developed across the Canterbury basin at nine strong motion stations using a combination of active and passive surface wave methods and horizontal to vertical spectral ratio measurements. A multi-mode, multi-method joint inversion process, which included Rayleigh and Love wave dispersion and horizontal to vertical spectral ratio data, was used to estimate the shear wave velocity profiles at each site. A-priori geologic information was utilized in defining preliminary constraints on the complex geologic layering of the Canterbury basin. At sites where interbedded layers were present, velocity reversals were considered in the inversion. …

Mitigation And Evaluation Of Alkali-Silica Reaction (Asr) And Freezing And Thawing In Concrete Transportation Structures, Richard Albert Deschenes Jr.

Graduate Theses and Dissertations

An evaluation of alkali-silica reaction (ASR) and freezing and thawing (F/T) in concrete transportation structures is presented along with mitigation methods for slowing the rate of deterioration in concrete. A combination of field and laboratory testing confirms ASR deterioration is exacerbated by exposure to F/T. Laboratory testing indicates an aggregate previously deemed inert to ASR, caused ASR deterioration in several concrete pavement and transportation structures. Existing standard test methods deem this aggregate safe for use in concrete. A modified test method shows the concrete can deteriorate rapidly when subjected to cycles of conditions promoting ASR and F/T. Several structures containing …

Geophysical Assessment Of Kinion Lake Dam, Tim Allen Moody

Graduate Theses and Dissertations

Geophysical methods including Capacitively-Coupled Resistivity (CCR), Electrical Resistivity Tomography/Imaging (ERT/ERI), Multichannel Analysis of Surface Waves (MASW) with Love and Rayleigh waves and a Full-Waveform Inversion (FWI) were performed on Kinion Lake Dam, an earth-filled embankment dam that has historically experienced significant seepage and internal erosion issues. Surveys were completed along the crest and downstream toe of the dam. Results from the surveys indicate that each method is capable of resolving the bedrock depth within 1-2 m of locations shown on previous drilling logs, though some discrepancies between the methods exist. A weathered bedrock layer is believed to have led to …

Optimization Of Concrete Mixtures For Use In Structural Elements, Waleed Almutairi

Graduate Theses and Dissertations

Portland cement is an essential ingredient in concrete. The use of cement is to enhance the strength as well as other hardened properties of concrete mixtures. Determining the accurate amount of cement is important because the required strength may not be achieved if not enough cement is used. By contrast, when using too much cement, concrete cracking may occur that leads to reducing durability. Researchers at the University of Arkansas (UA) have shown that many bridge decks achieve their 28 day design strength of 4000 psi by 7 days of age. Bridge decks having high strength may experience cracking, which …

Decision Support System For Container Port Selection Using Multiple-Objective Decision Analysis, Rivelino De Icaza

Graduate Theses and Dissertations

Ports are essential for maritime transportation and global supply chains since they are nodes that connect the sea- and land-based modes of transportation. With containerization and supply chains stimulating global trade, ports are challenged to adjust to changes in the market to create value to their customers. Therefore, this dissertation research focuses on the container port selection decision analysis to provide information to help shipping lines select the best port for their shipping networks. Since the problem is complex, dynamic, and involves multiple and conflicting criteria, the research proposes to use the multi-objective decision analysis with Value-Focused Thinking approach. The …

Essays In Measuring, Controlling, And Coordinating Supply Chain Inventory And Transportation Operations, Payam Parsa

Graduate Theses and Dissertations

Supply chain collaboration programs, such as continuous replenishment program (CRP), is among the most popular supply chain management practices. CRP is an arrangement between two partners in a supply chain to share information on a regular basis for lowering logistics costs while maintaining or increasing service levels. CRP shifts the replenishment responsibility to the upstream partner to avoid the bullwhip effect across the supply chain. This dissertation aims to quantify, measure, and expand the benefits of CRP for the purpose of reducing logistics cost and improving customer service. The developed models in this dissertation are all applied in different case …

Trihalomethane, Dihaloacetonitrile, And Total N-Nitrosamine Precursor Adsorption By Carbon Nanotubes: The Importance Of Surface Oxides And Pore Volume, Erin Needham

Graduate Theses and Dissertations

As drinking water sources become increasingly impaired, enhanced removal of natural organic matter (NOM) may be required to curb formation of disinfection byproducts (DBPs) upon chlor(am)ination. While carbon nanotubes (CNTs) can adsorb NOM, their properties for DBP precursor adsorption have not been elucidated. Nine types of CNTs were assessed for trihalomethane (THM), dihaloacetonitrile (DHAN), and total N-nitrosamine (TONO) precursor adsorption. Batch isotherm experiments were completed with lake water and, to simulate an impaired condition, effluent from a wastewater treatment plant (WWTP). Adsorption varied with CNT type and dose, with TONO precursors having the highest percent removals from WWTP effluent (up …

Effect Of Column Axial Load On Skewed Smf Rbs Connection Demands, Clovis Desrochers

Graduate Theses and Dissertations

Steel buildings in high seismic areas often require special structural systems to transfer large lateral forces induced by earthquake accelerations. The selection of an appropriate seismic steel system (braced frame, moment frame, shear wall, etc.) is often influenced by architectural considerations. Moment frame configurations offer the most architectural flexibility, but are limited by code prequalification requirements that limit the use of non-orthogonal (skewed) beam-column connection geometries. A recent study has investigated laterally skewed moment frame connections, indicating that skew increases the potential for column twist and column flange yielding; however, it is unclear how realistic column axial loads will affect …

Development Of A Multiband Remote Sensing System For Determination Of Unsaturated Soil Properties, Cyrus D. Garner

Graduate Theses and Dissertations

A multiband system including active microwave sensing and visible-near infrared reflectance spectroscopy was developed to measure unsaturated soil properties in both field and laboratory environments. Remote measurements of soil volumetric water content (θv), soil water matric potential (ψ), and soil index properties (liquid limit [LL], plastic limit [PL], and clay fraction [CF]) were conducted. Field-based measurement of θv was conducted using a ground-based radar system and field measurements within 10 percentage points of measurements acquired with traditional sampling techniques were obtained. Laboratory-based, visible and near infrared spectroscopy was found to be capable of obtaining empirical, soil specific regression functions (partial …

A Comparison Of Force And Pressure Coefficients On Dome, Cube And Prism Shaped Buildings Due To Straight And Tornadic Wind Using Three Dimensional Computational Fluids Dynamics, Majdi A. A. Yousef

Graduate Theses and Dissertations

Tornadoes induce very different wind forces than a straight-line (SL) wind. A suitably designed building for a SL wind may fail when exposed to a tornado-wind of the same wind speed. It is necessary to design buildings that are more resistant to tornadoes. Most studies have been conducted to investigate tornado forces on cubic, gable-roof and cylinder buildings. However, little attention has been paid to investigate tornado force on dome buildings; hence, further research is conducted in this study. The forces on a dome, cube and prisms were analyzed and compared using Computational Fluid Dynamics (CFD) for tornadic and SL …

Understanding N-Nitrosodimethylamine Formation In Water: Chloramine Chemistry, Kinetics, And A Proposed Reaction Pathway, Huong Thu Pham

Graduate Theses and Dissertations

The formation of N-nitrosodimethylamine (NDMA) in drinking water systems is a concern because of its potential carcinogenicity and occurrence at toxicologically relevant levels. The postulated mechanism for NDMA formation involves a substitution between dichloramine and amine-based precursors to form an unsymmetrical dimethylhydrazine (UDMH), which is then oxidized by ground-state molecular oxygen to form NDMA. However, this latter reaction is spin forbidden, thus likely occurs at a slow rate. It is hypothesized that the reaction between monochloramine and hydroxylamine (a nitrification product) may form an intermediate, which is involved in the NDMA formation pathway. This intermediate may also be generated from …

Exploring Compaction Effects On Cold In-Place Recycling Mixtures Using Emulsified Asphalt, Erica Ann Yeung

Graduate Theses and Dissertations

Cold in-place recycling (CIR) is a process that takes three to four inches of existing pavement surface and reuses 100% of it by milling and crushing it, adding asphalt emulsions and/or additives to it, before placing and re-compacting it. There is currently very little research regarding the interaction between the crushed aggregate and asphalt emulsion during the CIR process. In this study, the interactions between the combinations of crushed aggregates and asphalt emulsions were investigated along with select compaction metrics and a raveling performance test. The three types of aggregates included coated limestone, recycled asphalt pavement (RAP), and coated syenite. …

Feasibility Of Additive Manufactured Materials For Use In Geotechnical Laboratory Testing Applications, Matthew P. Watters

Graduate Theses and Dissertations

The factors affecting the positive volumetric strain, or dilatancy, typically observed in response to shearing of a dense granular material have long been investigated; however, there still lacks a direct relationship between particle shapes and the resulting dilatant response. The typical Mohr-Coulomb strength parameter associated with granular material is known as the effective friction angle (φ’). For a dense granular assemblage, the peak friction angle has been described as being comprised of a dilatant friction angle (φ’d) component and a critical state friction angle (φ’cv) component. While the topic of dilatancy and factors (both inherent and extrinsic) affecting its behavior …

Total N-Nitrosamine Precursor Adsorption With Carbon Nanotubes: Elucidating Controlling Physiochemical Properties And Developing A Size-Resolved Precursor Surrogate, Erin Needham

Graduate Theses and Dissertations

As drinking water sources become increasingly impaired with nutrients and wastewater treatment plant (WWTP) effluent, formation of disinfection byproducts (DBPs) – such as trihalomethanes (THMs), dihaloacetonitriles (DHANs), and N-nitrosamines – during water treatment may also increase. N-nitrosamines may comprise the bulk of the chronic toxicity in treated drinking waters despite forming at low ng/L levels. This research seeks to elucidate physicochemical properties of carbon nanotubes (CNTs) for removal of DBP precursors, with an emphasis on total N-nitrosamines (TONO).

Batch experiments with CNTs were completed to assess adsorption of THM, DHAN, and TONO precursors; physiochemical properties of CNTs were quantified through …