Civil Engineering Commons^™

The Aerodynamic And Dynamic Loading Of A Slender Structure By An Impacting Tornado-Like Vortex: The Influence Of Relative Vortex-To-Structure Size On Structural Loading, Matthew Nicholas Strasser

Graduate Theses and Dissertations

Structural loading produced by an impacting vortex is a hazardous phenomenon that is encountered in numerous applications ranging from the destruction of residences by tornados to the chopping of tip vortices by rotors. Adequate design of structures to resist vortex-induced structural loading necessitates study of the phenomenon that control the structural loading produced by an impacting vortex. This body of work extends the current knowledge base of vortex-structure interaction by evaluating the influence of the relative vortex-to-structure size on the structural loading that the vortex produces. A computer model is utilized to directly simulate the two-dimensional impact of an impinging …

Application Of Polyacrylamide-Based Floc Logs For Turbidity Control At Highway Construction Sites, Kien Ngo

Graduate Theses and Dissertations

Runoff waters generated on highway construction sites can have turbidities in excess of the proposed EPA regulatory standard of 280 NTU due to large areas of exposed soil. The objective of this research was to develop best management practices (BMPs) for the use of anionic polyacrylamide (PAM) based Floc Logs, for turbidity control. Five commercially available types of PAM-based Floc Logs were evaluated in jar tests, using soil excavated from Cato Springs Research Center (CSRC, Fayetteville AR) and six types of clay from the Clay Minerals Society (Chantilly, VA). These results show that no single Floc Log type was suitable …

Comparative Analysis Of Buckling-Restrained Braced Frames In Eccentric Configuration (Brbf-Es) And Eccentrically Braced Frames (Ebfs), Peter T. Vayda

Civil Engineering Undergraduate Honors Theses

Continuing on the findings of “Using Buckling-Restrained Braced Frames in Eccentric Configuration,” by Dr. Gary S. Prinz, P.E., which determined that, from a performance standpoint, BRBF-Es could be a viable alternative for EBFs. A comparative analysis was conducted on the design procedures and initial cost estimates of BRBF-Es and EBFs. Upon designing four 12-Story buildings (two BRBF-Es and two EBFs), it was determined that BRBF-Es were easier to design due to the statically determinant system. The initial costs estimates of BRBF-Es; however, ranged upwards of 30% more cost than EBFs. Therefore, the initial investment of more intensive structural engineering design …

Alkali Silica Reaction Mitigation Using High Volume Class C Fly Ash, William Joseph Phillips

Graduate Theses and Dissertations

Alkali-Silica Reaction (ASR) is a neutralization reaction that occurs between an acid (silicic acid) and a basic pH pore solution (Calcium Oxide, Potassium Oxide, and Sodium Oxide). ASR causes deleterious expansion within concrete, which can cause durability issues decreasing the life span of concrete. ASR in concrete has been found in increasing quantities since its discovery in 1940 by Stanton. Several cases of ASR have occurred in Arkansas near Fayetteville, Pine Bluff, and Little Rock. The purpose of this research was to develop preventative measures using Class C fly ash in concrete, which contains the moderately reactive aggregates found in …

Value Focused Inland Waterway Infrastructure Investment Decisions, Othman Boudhoum

Graduate Theses and Dissertations

Maritime transportation functions as the backbone of world trade. The U.S. inland waterway transportation system is comprised of 12,000 miles of navigable waterways that connect and move freight between the global supply chain and thirty eight States. When investing in inland waterway infrastructure, we should aim to maximize all benefits associated with the investment including flood protection, water supply, hydropower generation, recreation, and environmental impact benefits. We formulate an initial qualitative value model for the inland waterway infrastructure investment decision based on a value-focused thinking approach which allows us to holistically evaluate project investment alternatives. Given limited resources, a portfolio …

Development Of Best Management Practices For Turbidity Control During Rainfall Events At Highway Construction Sites Using Polyacrylamide, Joanne Johnson

Graduate Theses and Dissertations

In 2009, the United States Environmental Protection Agency (EPA) promulgated a national turbidity standard for runoff water leaving highway construction sites at 280 nephelometric turbidity units (NTU). Meeting this standard can be challenging as turbidities of runoff waters can exceed 15,000 NTU. The objective of this research was to assess polyacrylamide (PAM), a coagulant aid used in water treatment, to help meet the EPA turbidity regulation. Twelve commercially available PAM types were studied, selected on the basis of charge type (cationic, nonionic, anionic), charge density (0-100%), and molecular weight (0.1-28 Mg mol-1). Jar tests were conducted with runoff waters from …

Laboratory Comparison Of Full Depth Reclamation Stabilization Techniques Using Arkansas Field Materials, Chase Aaron Henrichs

Graduate Theses and Dissertations

Full depth reclamation (FDR) is a flexible pavement recycling technique that has not been explored in the state of Arkansas. FDR is unique in that it incorporates the entire flexible pavement section as well as a predetermined portion of the underlying base and sub-base materials with a stabilizer to create a new, stronger stabilized base course. Common stabilization techniques include the addition of asphalt emulsion, asphalt foam, or cement. Using the North Carolina emulsion FDR mix design, the Wirtgen foam FDR mix design, and the Portland Cement Association cement FDR mix design, field materials from four Arkansas highways in the …

Comparing Layer Types For The Use Of Mepdg For Fdr Design, Sadie Smith

Graduate Theses and Dissertations

While Full Depth Reclamation (FDR) has many potential cost and environmental benefits, especially over the lifetime of the pavement, it is necessary to be able to ensure that the recycled pavement will perform adequately. One way in which this can be accomplished is understanding how to best complete the structural design of FDR pavements. Because FDR is a combination of several different layers of material pulverized, mixed, stabilized and re-compacted, it does not fit neatly into any of these predetermined types of materials considered by the Mechanistic Empirical Design Guide (MEPDG). Current practice is to treat FDR as an unbound …

Three Dimensional Simulations Of Tornado Sheltering Effect Of Man-Made Structures, Piotr Gorecki

Graduate Theses and Dissertations

A three dimensional computational fluid dynamics (CFD) model was utilized to investigate tornado-like vortex interactions with wide man-made structures. The tornado-like wind profile was approximated using Rankine vortex model. By utilizing the CFD model, it was explained why tornadoes exhibit less damage on leeward side of large structures. During the preliminary stage of this study, a perpendicular vortex-prism interaction was analyzed. The prism height and the length were equal to the vortex core radius. The prism was also 12 times wider than the vortex core radius. During the vortex-prism interaction, the near-ground portion of the vortex was blocked by the …

Amount Of Uncertainty In The Methods Utilized To Design Drilled Shaft Foundations, Morgan Race

Graduate Theses and Dissertations

In 2001, load and resistance factor design (LRFD) for deep foundations was required by the American Association of State Highway and Transportation Officials (AASHTO). Following implementation of LRFD, localized calibration of resistance factors using data from the states of Colorado, Florida, Kansas, Louisiana/Mississippi, Missouri allowed these states to utilize higher resistance factors during design. However, characterizing the uncertainty in the design of DSF, regarding the geotechnical investigation methods and the utilized software programs, higher values of resistance factors may be calibrated to more efficiently design DSF with the same level of reliability.

Three test sites within the state of Arkansas, …

Alkali-Silica Reaction Mitigation Using High Volume Class C Fly Ash, Sydney Marie Dickson

Civil Engineering Undergraduate Honors Theses

Fly ash is the residue produced from coal combustion in electric generating plants. There are two types of fly ash, Class C and Class F. Approximately 40 percent of fly ash generated from coal combustion can be used as a partial replacement of cement in concrete. Incorporating fly ash improves concrete properties and extends its service life. Alkali-silica reaction (ASR) is an expansive reaction between reactive silica typically found in aggregates (rock and sand) and alkalis in cement. This reaction results in the formation of a gel that absorbs water and swells, which exerts an internal pressure in concrete. This …

Drive Plate Mass Polar Moment Of Inertia In Stokeo Type Resonant Column Devices, Michael Ryan Deschenes

Civil Engineering Undergraduate Honors Theses

The calibration procedure employed by researchers at the University of Arkansas (UA) to calibrate two Stokoe-type resonant column torsional shear (RCTS) devices is presented herein. Specifically, the development of a device-specific calibration process to determine the mass polar moment of inertia of the RCTS drive plate assemblies (J0), as a function of frequency, is described. Three aluminum calibration specimens and three stainless steel masses with known geometric and material properties were utilized to experimentally determine the J0 values. Experimental data collected by researchers at the University of Arkansas and obtained from other sources (Utah State University, the University of Texas …

Evaluation Of The Equations Used To Calculate Hydraulic Conductivity Values From Two-Stage Borehole Tests, Johnathon Dale Blanchard

Civil Engineering Undergraduate Honors Theses

A compacted clay liner (CCL) test pad was constructed for the purpose of evaluating the testing procedures utilized for determining hydraulic conductivity of a CCL. These procedures include ASTM D6391 (2014) Method C and ASTM D6391 Method A. Method C was recently added to ASTM D6391(2014) and was evaluated based upon comparison of results obtained from previous research with results from the data presented herein. The test pad was instrumented with volumetric water content probes and water matric potential sensors to monitor the wetting front in the soil. The data obtained from this instrumentation should be used to develop a …

Development Of Optimal Experimental Design Parameters For Pseudo Ambient Vibration Testing Of Bridges, David Samudio Castillo

Civil Engineering Undergraduate Honors Theses

The United States of America is facing an infrastructure crisis that is characterized by aging and deteriorating structures, a significant backlog of maintenance and upgrades for existing infrastructure, limited funding and lack of practical and effective tools for identifying and prioritizing the most pressing infrastructure needs. The American Association of Civil Engineers (ASCE) qualifies America’s infrastructure with a D+(ASCE Report Card). This rating reflects the general state of infrastructure that is unlikely to improve dramatically in the short-term, yet the situation costs the nation billions of dollars annually due to losses in economic efficiency and productivity, and in some cases …

A Study Of The Influence Of Particle Gradation In Bonded Assemblies, Matthew P. Watters

Civil Engineering Undergraduate Honors Theses

The discrete element method (DEM) has been used extensively to study soil, rock, and masonry behavior because of its ability to model the materials as individual particles or bonded clumps of particles. DEM allows for examination of the macro- and micro-scale response and provides a means to study the fundamental material behavior, but it is still considered computationally expensive in relation to other methods. To lower computational costs, the smallest particle sizes are often considered negligible and are left out of the model. Additionally, rock or intact materials are often modeled as a bonded assembly of uniform spheres. To date, …

Measurement Of Transfer And Development Lengths Of 0.7 In. Strands On Pretensioned Concrete Elements, Canh Ngoc Dang

Graduate Theses and Dissertations

The implementation of 0.7 in. (17.8 mm), Grade 270 (1860), low-relaxation prestressing strands in construction is slow regardless of its advantages over the use of 0.6 in. (15.2 mm) and 0.5 in. (12.7 mm) strands. The limited research data and unavailable design guidelines partially account for the slow utilization. This study measured transfer and development length, and evaluated applicable strand spacing of 0.7 in. (17.8 mm) prestressing strands for 24 pretensioned concrete beams. Each beam contained one prestressing strand or two prestressing strands placed at spacing of 2.0 in. (51 mm). The beams were fabricated with high strength, conventional concrete …

Analyzing Stochastically Generated Material Properties For The Use In Mumerical Simulations Of Advanced Laboratory Tests Of Asphalt Concrete, Ken K. Rutabana

Civil Engineering Undergraduate Honors Theses

For such a large country as the US, adequate road transportation is a vital necessity that ensures the safety, prosperity, and development of the people. Covering 94% of the two million miles of paved roads and highways, asphalt concrete is essential to this country. This is one reason why it is crucial to understand the potential and limitations of asphalt concrete. Unfortunately, material testing is a costly and time consuming ordeal. Consequently, numerical modeling of asphalt testing using computer software has been successfully developed in the last decades. These models corroborate those obtained in the lab but are intended as …

Selection Of A Realistic Viscous Vortex Tangential Velocity Profile For Computer Simulation Of Vortex-Structure Interaction, M. N. Strasser, R. P. Selvam

Journal of the Arkansas Academy of Science

Structure loading by vortices is a relevant phenomenon in numerous fields of engineering significance. Computer modelling is a powerful tool that can be used to study the loading produced on structures by impacting vortices. Realistic simulation of vortex-loading of structures necessitates the use of a realistic vortex tangential velocity profile (TVP). The present study compiles measured TVPs from various types of experimentally-produced vortices as well as real-world tornado and hurricane vortices. The measured TVPs are compared with commonly-used, analytical TVPs. Analytical TVPs that realistically represent the range of measured TVPs are identified and selected for use in future computer simulation …