Civil and Environmental Engineering Commons^™

Impact Of Curing Time And Curing Stress On The Mechanical Behavior Of Cement-Improved And Cement-Fiber-Improved Soft Soil, Ryan Daniel Starcher

Theses and Dissertations

In order to improve the engineering properties of soft soils, materials, such as cement and fiber, can be introduced to the soil mass. Currently, design criterion for a cement-soil mixture requires only the measurement of unconfined compressive strength. This simple measurement may not be adequate to describe the behavior that results from differing field loading conditions. A series of consolidation tests and unconfined compression tests were conducted with special attention being paid to the effects of curing time and vertical curing stress. It is shown that the introduction of cement into soft soils results in decreased compressibility and increased unconfined …

Size Kinetics And Mechanics Of Clay-Biopolymer Flocs, Hang Yin

LSU Doctoral Dissertations

The suspended cohesive sediments, mostly clay minerals with negative surface charges, usually interact through an array of intermolecular/surface forces (e.g., Coulomb force, van der Waals attractions, and hydrogen bonding) with waterborne organic matter (e.g., exopolymers) and dissolved salts, resulting in fractal, tenuous, and hybrid organic-inorganic flocs or “marine snow”. A pilot and systematic laboratory and theoretical work have been conducted towards a synthetic nanoscale understanding of the flocculation kinetics and mechanics of the clay-exopolymer micro-sized flocs. This systematic study has achieved two impressive objectives: (1) the effect of exopolymer polarity and concentration on the particle size kinetics of clay-exopolymer mixtures …

Exploring Travel And Activity Behavior In Transit-Oriented Developments: Insights Into Transportation Benefits And Travel Demand Modelling, Sanghoon Son

Civil & Environmental Engineering Theses & Dissertations

As a sustainable urban development and transportation planning strategy, researchers and planners are increasingly interested in transit-oriented development (TOD). By integrating transit system and neighborhood design, TOD aims to provide a livable environment that is alternative mode friendly, higher density, and mixed-use to residents and workers in the vicinity of transit stations. Despite the recent growing interest in TOE), however, transportation benefits of TOD are not well quantified and characteristics of TOD are not adequately reflected in travel demand models.

This dissertation contributes to understanding of the travel and activity behavior by comprehensively exploring them in the context of TOD. …

Thermo-Elasto-Plastic Behavior Of Biaxially Loaded Steel Beam-Columns Inducing Those From World Trade Center Towers, Yanhong Zhao

Civil & Environmental Engineering Theses & Dissertations

An experimental and theoretical investigation into the behavior of biaxially loaded steel beam-columns is conducted including the effects of high temperature. Systems of materially nonlinear differential equations of beam-column equilibrium are first formulated for both ambient and high temperature conditions. An iterative finite integral procedure is formulated and programmed to solve the governing differential equations. To check the validity of the theoretically predicted behavior and strength of the beam-columns, a series of forty-two laboratory tests are conducted at both ambient and high temperature up to 950°F. Upon achieving a good agreement between the predicted beam-column behavior and that observed in …

Watershed-Scale Hybrid Stochastic-Deterministic Modeling Framework And Diffused Sources Superpositioning, Ruby Juvah Damalie

Civil & Environmental Engineering Theses & Dissertations

Predicting hydrologic system behavior is imperative to planning and management of water resources. The study developed an integrated hybrid stochastic and deterministic framework to improve prediction accuracy for overland flow and diffused sources in a watershed. The methodology includes sampling input parameters at system level and contribution of nonpoint source from hydrologically disconnected areas (heretofore referred to as system-level approach and superpositioning respectively). System-level approach includes the integration of a topography-based sampling grid generalized linear model developed by the study and Monte Carlo methods. The superpositioning method adopts in-stream water quality equation for overland flow pollution estimation.

The system-level approach …

Enamel Coated Steel Reinforcement For Improved Durability And Life-Cycle Performance Of Concrete Structures: Microstructure, Corrosion, And Deterioration, Fujian Tang

Doctoral Dissertations

"This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl …

Phytoforensics On Energetics: Novel Plant Tissue Measure Approach And Modeling, Yuan Yuan

Doctoral Dissertations

"Explosives and energetics are common soil and groundwater pollutions. This research was to develop novel phytoforensics approaches on energetics. Four different plants species, including woody perennial trees and monocot grasses, were planted both in soil and sand reactors with continuous exposure to a mixture of explosives in the greenhouse. Time dependent assessments were carried out to determine kinetic mechanisms of uptake, transport and accumulation. Plant concentrations were analyzed by both traditional solvent extraction and novel sap analysis methods. A dynamic soil-plant system model was developed to quantify the relationship between tissue concentration and soil pore water concentration for non-volatile organic …

Effect Of Mix Parameters On Longevity Of Bituminous Mixtures, Clayton Reichle

Masters Theses

"This study was performed to evaluate the effects of varying aggregate sources, aggregate gradations on the stripping and rutting potential of bituminous based plant mixes specified by the Missouri Department of Transportation. The different aggregate combinations included two different aggregate sources (Potosi Dolomite and Jefferson City Dolomite) including two variations for the Jefferson City Dolomite mix to simulate a marginally in-specification mix and an out-of-specification but in-field tolerance mix. The "field" mix simulated the marginal mix where field tolerance of high dust and low binder content were maximized. All three mixes were evaluated for stripping susceptibility using the Tensile Strength …

Selection And Clustering For Disease Associated Genetic Variants, Yubo Zou

Theses and Dissertations

Epigenetics is the study of chemical reactions, which are orchestrated for the development and maintenance of an organism. Genetic or epigenetic variants (GEVs) encompass different types of genetic measures, such as Deoxyribonucleic acid (DNA) methylation at different CpG sites, expression level of genes, or single nucleotide polymorphisms (SNPs). With the development of technology, huge amount of genetic and epigenetic information is produced. However, the rich information potentially brings in challenges in data analyses. Thus it is necessary to reduce the dimension of data to improve efficiency. In my dissertation, I will focus on two directions of dimension reduction: variable selection …

A Method To Reduce Plastic Shrinkage Cracking Of Concrete Using Re-Vibration Technique, Mustafa Abushaala Aldalinsi

Open Access Theses & Dissertations

One of the problems that reduce durability; thus, performance of concrete is the development of plastic shrinkage cracking (PSC). Traditionally, the development of PSC has been minimized by controlling its exposure to weather conditions or by adding fibers. In this study, concrete re-vibration was used as an alternative technique to control PSC because of the limited availability of fibers in the developing countries. In this study, the wait time after slab casting and before vibration was selected to be 90 minutes while length of re-vibration time was varied from 15 to 45 seconds. Also, the water-cement ratios were selected to …

Characterization Of Particulate Matter Concentrations (Pm10, Pm10-2.5, And Pm2.5) At High-Altitude School And Residential Mircroenvironments In Quito, Ecuador, Teresa Montoya

Open Access Theses & Dissertations

Air quality issues in Latin American countries are especially challenging because of the limited availability of resources to address them, lack of stringent standards and the rapid and uncontrolled growth of their cities increasing the number of vehicles on the road and the expansion of the industry. In particular, the city of Quito, Ecuador exacerbates its environmental issues by its high-altitude (2800 m above sea level) coupled by its location around a mountain valley and frequent temperature inversions.

This study focused on evaluating the spatial variation of the PM concentrations and the effectiveness of a central monitoring network in representing …

Model Fusion: A New Approach To Processing Heterogeneous Data, Omar Ochoa

Open Access Theses & Dissertations

In many practical situations, it is necessary to extract

information from data of different types. For example, in geosciences, several sources of data can be used to determine the interior structure of the earth: the first arriving waves from earthquakes and from man-made sources, measurements of the earth's gravity field, measurements of the dispersion of surface waves generated by earthquakes, etc. At present, most existing data processing techniques deal only with data of one type.

A joint use of all the information derived from multiple types of data sources is an important theoretical and practical challenge. Such a joint use …

Development Of The Strategy To Select Optimum Reflective Cracking Mitigation Methods For The Hot-Mix Asphalt Overlays In Florida, Hamid Maherinia

Electronic Theses and Dissertations

Hot Mix Asphalt (HMA) overlay is a major rehabilitation treatment for the existing deteriorated pavements (both flexible and rigid pavements). Reflective cracking (RC) is the most common distress type appearing in the HMA overlays which structurally and functionally degrades the whole pavement structure, especially under high traffic volume. Although many studies have been conducted to identify the best performing RC mitigation technique, the level of success varies from premature failure to good performance in the field. In Florida, Asphalt Rubber Membrane Interlayers (ARMIs) have been used as a RC mitigation technique but its field performance has not been successful. In …

Analytical And Experimental Study Of Monitoring For Chain-Like Nonlinear Dynamic Systems, Bryan Paul

Electronic Theses and Dissertations

Inverse analysis of nonlinear dynamic systems is an important area of research in the eld of structural health monitoring for civil engineering structures. Structural damage usually involves localized nonlinear behaviors of dynamic systems that evolve into different classes of nonlinearity as well as change system parameter values. Numerous parametric modal analysis techniques (e.g., eigensystem realization algorithm and subspace identification method) have been developed for system identification of multi-degree-of-freedom dynamic systems. However, those methods are usually limited to linear systems and known for poor sensitivity to localized damage. On the other hand, non-parametric identification methods (e.g., artificial neural networks) are advantageous …

Effect Of Suction On Dynamic Properties Of Unsaturated Soils At Mid- To High-Shear Strain Amplitudes, Alejandro Hernan Pino Bravo

Civil Engineering Theses - Archive

This paper presents the results from an experimental study that has been designed to assess the effect of the suction and net mean stress on the dynamic properties of poorly graded sand with silt subjected to small- to mid-shear strains. The practical implication of this study includes determining the effect on soil stiffness properties of increased matric suction (transpiration of water) at different net mean stresses (or depths) in the field. The engineering analysis of earth structures subjected to static and non-static loading under unsaturated conditions requires knowing the relevant parameters of the soil, such as shear wave velocity, shear …

Lrfd Pullout Resistance Factor Calibration For Soil Nails Incorporating Survival Analysis And Plaxis 2d, Brett Devries

Civil Engineering Theses - Archive

The use of soil nail walls (SNWs) in the United States has increased since their introduction in the mid-1970's, to where currently the analysis, design and construction are commonly performed (Lazarte, 2011). These SNW designs were mostly based on ASD methods and LRFD-based methodologies were lacking until the 1998 FHWA manual on SNW design (Byrne, Cotton, Porterfield, Wolschlag and Ueblacker, 1998), which provided uncalibrated resistance factors developed from ASD safety factors. As a result, little improvement was made toward a more efficient design, until fully calibrated LRFD pullout resistance factors were provided in the NCHRP Report 701 (Lazarte, 2011). These …

Two-Dimensional Hydrodynamic Modeling Of Two-Phase Flow For Understanding Geyser Phenomena In Urban Stormwater System, Zhiyu S. Shao

Theses and Dissertations--Civil Engineering

During intense rain events a stormwater system can fill rapidly and undergo a transition from open channel flow to pressurized flow. This transition can create large discrete pockets of trapped air in the system. These pockets are pressurized in the horizontal reaches of the system and then are released through vertical vents. In extreme cases, the transition and release of air pockets can create a geyser feature.

The current models are inadequate for simulating mixed flows with complicated air-water interactions, such as geysers. Additionally, the simulation of air escaping in the vertical dropshaft is greatly simplified, or completely ignored, in …

Camber Control In Simply Supported Prestressed Concrete Bridge Girders, Osamah Ibrahim Mahmood

Theses and Dissertations--Civil Engineering

When designing a bridge, serviceability usually controls and is a more important factor than the ultimate capacity of the bridge or the allowable stresses. Therefore, the behavior of the bridge girder deflection and camber must be predicted as accurately as possible. Therefore, excessive camber has become one of the most common problems when constructing concrete bridges. Different methods have been developed to overcome this problem. The most common and widely used is using haunch with adjustable pedestals to overcome the excessive camber. However, this method has limitations that must be considered. Therefore, this study is evaluating the effectiveness of using …

Biological Control Of Manganese In Water Supplies In The Presence Of Humic Acids, Michael S. Snyder

Theses and Dissertations--Civil Engineering

The main objective of this study was to improve our understanding of biological filtration (biofilm type) treatment for manganese (Mn) removal in drinking water. Biological filtration treatment involves biofilms of Mn(II)-oxidizing microorganisms attached to solid filter material that remove and immobilize dissolved Mn(II) in raw water by conversion to black MnO_2(s) precipitates. Mn-biological filtration is an emerging green technology that can serve as an alternative to conventional physicochemical treatments but its full potential is hindered by various factors. These include lack of understanding the: (1) optimal removal conditions for Mn, (2) mechanisms for Mn releases of the accumulated Mn …

Unsaturated Soil Parameters From Field Stiffness Measurements, Jason M. Curd

Theses and Dissertations--Civil Engineering

The behavior of unsaturated soils depends heavily on material properties and soil conditions. In Geotechnical Engineering, compacted soils are frequently used as fill material, and quality control is vital to the construction process. There are few methods available to estimate the parameters associated with unsaturated soils based on field measurements, and a relationship between these factors could reduce testing time and lower construction costs. Undrained triaxial tests were performed on four clays representing a range of material properties in an effort to reach the maximum dry density, which provides the highest bearing capacity. Each clay was compacted at optimum moisture …

Moisture And Unit Weight Readings From A Complex Impedance Measuring Instrument, Kirk Andrew Jenkins

Theses and Dissertations--Civil Engineering

Complex Impedance Measuring Instruments (CIMI’s) are non-nuclear devices that calculate the dry unit weight and moisture content of soil by means of electromagnetic wave propagation theory. Unlike nuclear based test devices, these devices do not require certification or elaborate maintenance to own and operate. CIMI operation requires a soil specific calibration process where soil moisture and unit weight are correlated to electrical parameters. A new, smaller acrylic mold was developed as an alternative calibration tool to the manufacturer’s recommended mold. Calibrated soil models were generated using manufacturer recommended procedures as well as new procedures involving an acrylic mold. Models were …

Applying Cognitive Principles To The Delivery Of Engineering Information By Different Mediums, Gabriel B. Dadi

Theses and Dissertations--Civil Engineering

Construction project performance and worker productivity are often tied to the availability and effective presentation of information, tools, materials, and equipment. While advancements in technology have improved much of the processes on a construction project, the medium of information dissemination at the construction work face has consistently relied on the use of two dimensional drawings and specifications.

Industry initiatives are driving increased collaboration through three dimensional BIM (Building Information Modeling) models. However, the added dimension partially loses its effect when presented on a two dimensional computer monitor. Other computer forms of presentation intended for mobility (PDAs, laptops, and tablets) can …

Water Quality Sensor Placement Guidance For Small Water Distribution Systems, Stacey L. Schal

Theses and Dissertations--Civil Engineering

Water distribution systems are vulnerable to intentional, along with accidental, contamination of the water supply. Contamination warning systems (CWS) are strategies to lessen the effects of contamination by delivering early indication of an event. Online quality monitoring, a network of sensors that can assess water quality and alert an operator of contamination, is a critical component of CWS, but utilities are faced with the decision of what locations are optimal for deployment of sensors. A sensor placement algorithm was developed and implemented in a commercial network distribution model (i.e. KYPIPE) to aid small utilities in sensor placement. The developed sensor …

Kentrack 4.0: A Railway Trackbed Structural Design Program, Shushu Liu

Theses and Dissertations--Civil Engineering

The KENTRACK program is a finite element based railway trackbed structural design program that can be utilized to analyze trackbeds having various combinations of all-granular and asphalt-bound layered support. It is applicable for calculating compressive stresses at the top of subgrade, indicative of potential long-term trackbed settlement failure. Furthermore, for trackbeds containing asphalt layer, it is applicable for calculating tensile strains at the bottom of the asphalt layer, indicative of potential fatigue cracking. The program was recently expanded to include both English and international units. A procedure has been incorporated to provide a path to save results in a text …

Pressure Measurement At The Ballast-Tie Interface Of Railroad Track Using Matrix Based Tactile Surface Sensors, Michael T. Mchenry

Theses and Dissertations--Civil Engineering

The pressure distribution at the ballast-tie interface of railroad track plays a key role in overall track support. Failure of the ballast or tie can result from excessive loads that were not designed for, requiring increased maintenance and reducing railroad operating efficiency. Understanding the forces acting on the ballast and tie are required to design higher performance and longer lasting track. To further this understanding, the use of Matrix Based Tactile Surface Sensors (MBTSS) is employed to measure the actual pressure distribution at the ballast-tie interface, characterized by individual ballast particle contact points and non-uniform pressures. The research explores this …

Development Of A Constitutive Model Of Compacted Shales And Determination Of The Effect Of Weathering On Its Parameters, Isabel Cristina Gomez-Gutierrez

Theses and Dissertations--Civil Engineering

Compacted shales cause problems because they tend to degrade with time due to weathering. Degradation results in the shale deteriorating from a hard rock-like material to a soft fine-grained soil mass with lower shear strength and high deformability. Consequently, common problems that occur in embankments constructed with compacted shales include settlement and instabilities. Therefore, accelerating weathering prior to compaction by wetting and breaking down the shales before placement can reduce the deterioration during the service life of the construction. Extensive laboratory testing was performed in order to characterize the mechanical behavior of compacted shales.

Critical State theory is a clever …

Development Of A Design Based Intersection Safety Performance Evaluation Tool, Adam J. Kirk

Theses and Dissertations--Civil Engineering

The purpose of this research is to develop an intersection safety evaluation tool that is capable of assisting designers and planners in the assessment of alternative intersection designs. A conflict exposure model utilizing design hour volumes, intersection configuration and traffic control measures is proposed to achieve this goal. This approach makes use of data typically available for preliminary intersection design. The research goes beyond existing safety performance models which only examine non-directional average daily traffic (ADT) or practices which only account for the geometric and lane configuration of an intersection, such as conflict point analysis.

Conflict prediction models are developed …

Hydrologic Characterization Of A Rain Garden Mitigating Stormwater Runoff From A Commercial Area, John T. Mcmaine

Theses and Dissertations--Biosystems and Agricultural Engineering

Impervious surfaces such as roads, sidewalks, and roofs increase the volume of runoff generated in a watershed. Traditional stormwater management techniques emphasize conveyance of runoff away from impervious surfaces in order to reduce flooding. Rain gardens are becoming popular as a different means to manage stormwater in such a way that runoff is captured and infiltrated onsite rather than conveyed offsite. A stormwater management system consisting of a rainwater harvest system, rain garden, and infiltration chamber was built at the Coca-Cola Refreshments USA, Inc. distribution center in Lexington, Kentucky during the fall of 2011. Precipitation, inflow, and water level were …

Froth Flotation Performance Enhancement By Feed Cavitation And Magnetic Plastic Particle Addition, Mehmet Saracoglu

Theses and Dissertations--Mining Engineering

Froth flotation is the most commonly used process to recover and upgrade the portion of the coal preparation plant feed that has a particle size smaller than 150 microns. Problems that occur when employing froth flotation in the coal industry include i) coal surfaces that are weakly-to-moderately hydrophobic, and ii) flotation systems that are overloaded and limited by insufficient retention time.

Research was performed to evaluate techniques that could be implemented to improve flotation performance under the aforementioned scenarios. Pre-aeration of flotation feed using a cavitation system was extensively evaluated in laboratory and full-scale test programs. The benefits of adding …

Anchored Sheet Pile Wall Design In Expansive Soils, Ömer Bilgin, Eman Mansour

Civil and Environmental Engineering and Engineering Mechanics Faculty Publications

Expansive soils cause damage to civil engineering structures in various parts of the world, because they swell when absorb water and shrink when dry out. Due to swelling pressures, retaining walls can be subjected to additional lateral pressures causing increased wall deformations and bending moments. Anchor forces can also increase, if the walls are anchored. When expansive soils are present behind retaining walls, swell pressures should also be considered during design in addition to the traditional lateral earth pressures. This study proposes a method to predict potential swell pressures acting on retaining walls for use in design of these walls. …