A One‐Dimensional Model For Turbulent Mixing In The Benthic Biolayer Of Stream And Coastal Sediments,
2020
Virginia Tech
A One‐Dimensional Model For Turbulent Mixing In The Benthic Biolayer Of Stream And Coastal Sediments, Stanley B. Grant, Jesus D. Gomez‐Velez, Marco Ghisalberti, Ian Guymer, Fulvio Boano, Kevin Roche, Judson Harvey
Civil Engineering Faculty Publications and Presentations
In this paper, we develop and validate a rigorous modeling framework, based on Duhamel's Theorem, for the unsteady one‐dimensional vertical transport of a solute across a flat sediment‐water interface (SWI) and through the benthic biolayer of a turbulent stream. The modeling framework is novel in capturing the two‐way coupling between evolving solute concentrations above and below the SWI and in allowing for a depth‐varying diffusivity. Three diffusivity profiles within the sediment (constant, exponentially decaying, and a hybrid model) are evaluated against an extensive set of previously published laboratory measurements of turbulent mass transfer across the SWI. The exponential diffusivity profile …
Cement Stabilized Crushed Stone Base Course Strength And Stiffness Analysis,
2020
University of Arkansas, Fayetteville
Cement Stabilized Crushed Stone Base Course Strength And Stiffness Analysis, Andrew Deschenes
Graduate Theses and Dissertations
Approximately 70 – 80% of state departments of transportations (DOTs) utilize the 1993 AASTHO Guide for Design of Pavement Structures (1993 AASHTO) [1] for structural design of pavements. A growing portion of DOT’s are beginning to implement the Mechanistic-Empirical Pavement Design Guide (MEPDG), referred to as AASHTOWare Pavement ME [2]. The 1993 AASHTO flexible guide applies empirically derived unitless strength values referred to as structural layer coefficients and structural numbers (SN) to pavement thickness and pavement types. The 1993 AASHTO rigid flexible guide utilizes the depth and strength of the concrete pavement, with the composite spring constant (kc), which is …
An Investigation Into The Effects Of Fly Ash On Freeze-Thaw Durability Prediction,
2020
University of Arkansas, Fayetteville
An Investigation Into The Effects Of Fly Ash On Freeze-Thaw Durability Prediction, Yancy Schrader
Graduate Theses and Dissertations
Air is purposefully entrained into concrete primarily to improve resistance to freeze-thaw deterioration while saturated with water. Air entraining admixtures (AEAs) are chemical admixtures designed to entrain air into the concrete to provide adequate resistance to the effects of freezing and thawing. One of the challenges associated with air entrainment in concrete is the interaction of an AEA with supplementary cementitious materials present in the concrete, particularly fly ash. Fly ash is a by-product of the coal fired electrical generation industry, and often contains residual unburned carbon and other components that can increase the AEA demand of a particular concrete …
Effect Of Citric Acid On Slump, Compressive Strength, And Setting Time Of Belitic Calcium Sulfoaluminate Concrete,
2020
University of Arkansas, Fayetteville
Effect Of Citric Acid On Slump, Compressive Strength, And Setting Time Of Belitic Calcium Sulfoaluminate Concrete, Israel Aguilar Rosero
Graduate Theses and Dissertations
Belitic calcium sulfoaluminate (BCSA) cement has well established advantages related to fast setting time, fast strength gain, long-term strengths, shrinkage, and sustainability. Due to its fast setting and hardening, this type of cement has historically been used to repair concrete structures, highways, and runways. This work provides much needed guidance on establishing mix design criteria for BCSA cement. Guidance is also given on the effects of set retarders on strength, slump, and setting times. Citric acid and a phosphonic acid-based admixture were tested as retarders for different concrete mixtures. Three studies were performed. In the slump study five different water …
Seismic Loading Effects Within Orthogonally Connected Steel Lateral Force Resisting Systems,
2020
University of Arkansas, Fayetteville
Seismic Loading Effects Within Orthogonally Connected Steel Lateral Force Resisting Systems, Alhussin Faraj Aliwan
Graduate Theses and Dissertations
Steel buildings located within seismically active regions require special design considerations to ensure public safety and prevent collapse during an extreme seismic event. Two commonly used steel systems are special moment frames (SMFs) and buckling-restrained braced frames (BRBFs). When two seismic systems share a common column in an orthogonal configuration (such as at a building corner), design specifications currently consider a 100+30 rule wherein the shared column is designed for 100% fuse demand in one direction, plus 30% fuse demand from the other direction. While this rule has been shown to be reasonable for elastic building response, a few studies …
Using Bcsa Cement To Repair Waterway Transportation Structures,
2020
University of Arkansas, Fayetteville
Using Bcsa Cement To Repair Waterway Transportation Structures, Anazaria Johanis Ortega Gonzalez
Graduate Theses and Dissertations
Many maritime structures (e.g., locks, dams, ports) in the US are either reaching or are past their design lives, and there are limited funds for the necessary maintenance activities which can lead to repairs that requires closures. These structures are not easy to detour and often require dewatering before repairs can be made, closures can cause delays and business-related losses which can have a large effect on the nation’s economy. Thus, it is advantageous to reduce the repair time for maritime structures. BCSA (belitic calcium sulfoaluminate) cement is a promising material to perform this type of repair due to its …
Leveraging Biomimicry And Additive Manufacturing To Improve Load Transfer In Brittle Materials,
2020
University of Arkansas, Fayetteville
Leveraging Biomimicry And Additive Manufacturing To Improve Load Transfer In Brittle Materials, Ana Paula Bernardo
Graduate Theses and Dissertations
With the emergence of Additive Manufacturing (i.e., 3D printing) in construction, new strategically designed shapes can be created to improve load transfer through structural members and foundations. Cross-sections can be optimized to carry load using less material, or even using weaker constituent materials, like soils, which are cheap and abundant. The goal of this research is to investigate the benefits of using cellular patterns which leverage biomimicry in civil engineering applications, since nature has perfectly engineered materials and patterns which carry loads with the least amount of material possible. Most of the periodic cellular work to date has focused on …
Comparison Of Additively Manufactured And Wrought 17-4 Ph Stainless Steels In Ultra Low Cycle Fatigue,
2020
University of Arkansas, Fayetteville
Comparison Of Additively Manufactured And Wrought 17-4 Ph Stainless Steels In Ultra Low Cycle Fatigue, Timothy Strasser
Graduate Theses and Dissertations
Additive manufacturing (AM) processes allow for creation of complex geometries that are otherwise impractical to fabricate with traditional subtractive methods. AM technology has potential to improve the optimization of seismic lateral force resisting components which dissipate seismic energy through large plastic strains; however, the ultra low-cycle fatigue performance of AM metals are not yet well understood. Void formation during the AM fabrication process has potential to affect performance. This study compares the performance of heat-treated and non-heat-treated AM and wrought 17-4PH stainless steel in Ultra Low Cycle Fatigue. To understand ULCF performance differences between the AM and wrought specimens, post …
Behavior Of Concrete Structures Reinforced With High Strength Steel,
2020
University of Arkansas, Fayetteville
Behavior Of Concrete Structures Reinforced With High Strength Steel, Rahman S. Kareem
Graduate Theses and Dissertations
The structural strength and corrosion resistance of concrete members are improved when A1035 steel is used as the main reinforcement. The enhancement of A1035 is achieved by the modification of the composition and microstructure of the steel. Therefore, the behavior of concrete structures reinforced with high-performance steel (A1035) is different from those reinforced with the regular steel (A615). Concrete bridge decks reinforced with different amounts of A1035 were studied in this research program. The structural behavior of twelve concrete bridge decks reinforced with A615 Grade 420 (60 ksi) and A1035 Grade 830 (120 ksi) steel was investigated at both service …
A Methodological Framework To Evaluate Community Perceptions Of Economic And Safety Impacts Attributed To Highway Bypass And Widening Projects,
2020
University of Arkansas, Fayetteville
A Methodological Framework To Evaluate Community Perceptions Of Economic And Safety Impacts Attributed To Highway Bypass And Widening Projects, Karla Diaz-Corro
Graduate Theses and Dissertations
Transportation practitioners have proposed the construction of highway bypass and widening projects in rural communities to address traffic-related problems that include noise pollution and congestion, among others. In the past, the construction of bypass projects has led community residents to raise concerns about potential decreases in business activity for businesses located along the bypassed road. For transportation organizations, it is essential to understand the economic, social, and safety impacts of transportation projects in terms of public perceptions as public input is a required part of the project planning phase. Moreover, it is recommended that agencies perform retrospective analyses of project …
Moisture Monitoring Of A Clt Structure In A Southern Climate,
2020
University of Arkansas, Fayetteville
Moisture Monitoring Of A Clt Structure In A Southern Climate, Elizabeth Poblete
Graduate Theses and Dissertations
Understanding of moisture behavior in cross laminated timber (CLT) is critical to the widespread use of CLT in construction in the United States. Currently, very little data exists on the long-term impact of moisture on CLT. The objective of this research is to collect data regarding the long-term moisture variation in the CLT panel at the University of Arkansas Adohi Hall residence hall. The climate of Northwest Arkansas is different from previously monitored buildings, as they were in the Pacific Northwest. Comparatively, Northwest Arkansas has a warmer climate with higher average annual precipitation. Waterproofing efforts are usually employed to prevent …
Laboratory Study Of Hydrodynamics Of Submerged Bridges,
2020
University of Texas at Arlington
Laboratory Study Of Hydrodynamics Of Submerged Bridges, Max Thomson Dean
Civil Engineering Theses - Archive
Bridges are designed to withstand flood and debris loads; however, it is reported that 53% of bridge failures in the U.S. are caused by hydraulic events, including floods, scour, debris, and drifts. A series of scale flume experiments were conducted to determine flood force effects on bridge superstructures. 1:50 scale models of the Texas Department of Transportation’s typical reinforced concrete bridge superstructures were tested. The bridge superstructures included beams (TX28 and TX54 girders, slab beams, and box beams) and an accompanying bridge deck and railing. The drag and lift forces and overturning moments were measured by load sensors for various …
Developing Strength Reduction Factor For Flexural Design Of Reinforced Concrete Beams Exposed To Fire,
2020
University of Texas at Arlington
Developing Strength Reduction Factor For Flexural Design Of Reinforced Concrete Beams Exposed To Fire, Sahar Aradmehr
Civil Engineering Theses - Archive
Fire is a common hazard that may happen during the lifetime of concrete structures. Thus, it is one of the loads considered in building and tunnel design standards and codes. Dependency of the safety and structural integrity of a building to load-bearing elements such as beams requires the safe design of these elements. Flexural design of reinforced concrete (RC) beams under fire is critical. Typical load and resistance factor design (LRFD) of flexural member at ambient temperature deals with comparing the factored applied load with its capacity. Strength reduction factors are applied to the calculated nominal moment capacity to take …
Laboratory Tests And Numerical Model Of Geothermally Heated Bridge Deck With Attached Hydronic Loop,
2020
University of Texas at Arlington
Laboratory Tests And Numerical Model Of Geothermally Heated Bridge Deck With Attached Hydronic Loop, Teng Li
Civil Engineering Dissertations - Archive
An accumulation of ice and snow on pavement slabs and bridge decks always adversely impacts driving conditions and results in motorist accidents. The use of the more popular deicing methods, including plowing, salting, and sanding, is limited by their relatively high cost for materials, fuel, maintenance, and labor. Geothermal energy, which is considered a renewable, sustainable, clean (i.e., zero carbon emission), and directly used energy source, has been successfully applied to bridges and pavements for deicing. However, existing geothermal bridge and pavement deicing designs are primarily employed for new bridges where hydronic loops, which are considered internal heating, are embedded …
Experimental Investigation Of Anchor Group Effects On Concrete Breakout Strength Within Fiber Reinforced Concrete,
2020
University of Texas at Arlington
Experimental Investigation Of Anchor Group Effects On Concrete Breakout Strength Within Fiber Reinforced Concrete, Atheer Alaa Al Khafaji
Civil Engineering Theses - Archive
This research investigates the effect of anchor groups on concrete breakout strength within steel fiber reinforced concrete (SFRC) under tension load. High strength steel headed studs (F1554 Grade 105) in grouping action were cast-in-place within concrete specimens of different amounts of steel fibers. Four types of concrete mix designs were produced in the lab by using different amounts of steel fibers (0%, 0.5%, 1%, and 1.5%) by volume fraction of the mixture. The physical properties of steel fibers reinforced concrete were calculated through testing of specimens at the Civil Engineering Laboratory Building (CELB). In total, 12 cylinder specimens of 4-inch …
Hydrologic & Hydraulic Analyses To Re-Establish Trigg Branch’S Jurisdictional Channel To Pre-Dam Condition Using Hec-Hms & Hec-Ras Models,
2020
University of Texas at Arlington
Hydrologic & Hydraulic Analyses To Re-Establish Trigg Branch’S Jurisdictional Channel To Pre-Dam Condition Using Hec-Hms & Hec-Ras Models, Razak Ahmed Albarqaawee
Civil Engineering Theses - Archive
Birds strikes are the most prevalent cause of airplanes strikes, and retention ponds near airports are one of the most attractive spots for both immigrant and domestic wildlife USDA (2017). Since the Trigg Lake, water surface area covers around 46 acres and is located approx. 1.5 miles from four main runways, which make the lake a perfect shelter for birds to build their nests and eventually strike departing and/or landing aircraft. Based on a Federal Aviation Administration (FAA) advisory circular, no retention pond should be constructed within five miles of an airport nor should it have standing storm runoff for …
Development Of Deterioration Models For Street Pavement In Dallas-Fort Worth Metroplex,
2020
University of Texas at Arlington
Development Of Deterioration Models For Street Pavement In Dallas-Fort Worth Metroplex, Mladjan John Grujicic
Civil Engineering Dissertations - Archive
Accurate prediction of pavement deterioration is vital for an efficient and cost-effective allocation of available budgets for keeping an agency’s road networks operating at a desirable level. Currently, most cities in the Dallas-Fort Worth Metroplex area are using the software PAVERTM and the associated performance models to predict future conditions as they do not have available reliable prediction models. However, the problem with this type of modeling is that the models are not calibrated to local conditions. The Pavement Deterioration Prediction models that have been developed in this research will help any pavement management agencies within DFW Metroplex area to …
Hydration, Shrinkage, Cracking, And Mechanical Properties Of Cementitious Materials With Lignocellulosic Biomass Wastes.,
2020
University of Louisville
Hydration, Shrinkage, Cracking, And Mechanical Properties Of Cementitious Materials With Lignocellulosic Biomass Wastes., Aofei Guo
Electronic Theses and Dissertations
The disposal of lignocellulosic biomass wastes imposes a huge economic and environmental burden on this society. Recycling lignocellulosic biomass wastes and applying them to cementitious materials provides a sustainable and value-added way for both agriculture and concrete industries. To comprehensively identify the effect of lignocellulosic biomass wastes at different scales on cementitious materials, the hydration, shrinkage, cracking, and mechanical properties of cementitious materials with lignocellulosic biomass wastes were studied. Given the three different forms (powders, chips, and fibers) of lignocellulosic biomass wastes in this study, the research was implemented in three stages. In the first stage, hemp powders were collected …
Alternate Novel Thermal Structure Interaction Designs Of Molten Salt Shell Structures At High Temperatures Ranging From 565˚C To 700˚C,
2020
University of Nevada, Las Vegas
Alternate Novel Thermal Structure Interaction Designs Of Molten Salt Shell Structures At High Temperatures Ranging From 565˚C To 700˚C, Nathan David Tyrrell Loyd
UNLV Theses, Dissertations, Professional Papers, and Capstones
Excess energy from solar power stations and other baseline power production methods canbe stored in molten salts (MS) in the 565°C range, therefore allowing the use of large containers to store energy for up to a week and generate eight hours of electricity or more to be used during peak demand hours, at night, or adverse weather conditions, depending on the container size. Supported by Office of Naval Research (ONR), this research presents a survey of molten salt properties used in solar power storage, as well as the history of molten salt usage for energy storage and production for nuclear …
Use Of Time-Domain Reflectometry To Characterize Thermal And Hydraulic Properties Of Unsaturated Sands,
2020
University of Texas at Arlington
Use Of Time-Domain Reflectometry To Characterize Thermal And Hydraulic Properties Of Unsaturated Sands, Xuelin Wang
Civil Engineering Dissertations - Archive
Unsaturated soil is an essential consideration for many geotechnical engineering fields, for example, soil bearing capacity, soil lateral earth pressure, slope stability analysis, and seepage-related problems. Thermal-hydro-mechanical (THM) processes govern the behavior of unsaturated soils. Therefore, it is critical to simultaneously measure soil moisture, density, and thermal properties to better study THM processes. A thermo-time-domain reflectometry (thermo-TDR) sensor, a dual-probe for both soil moisture and thermal properties, is improved (based on its previous design) and fully calibrated through various soils at different soil moisture circumstances. Nine different chemical reagents with known dielectric constant were utilized to perform calibration of the …
