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Civil Engineering ETDs

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Full-Text Articles in Civil and Environmental Engineering

Laboratory Investigation Of Fatigue Endurance Limits In Asphalt Concrete, Damien Bateman Jul 2012

Laboratory Investigation Of Fatigue Endurance Limits In Asphalt Concrete, Damien Bateman

Civil Engineering ETDs

It is believed that Hot Mix Asphalt (HMA) mixtures used in long-lasting pavements contain a threshold of strain value below which no fatigue damage occurs. This concept is known as the fatigue endurance limit (FEL). Although previous studies have shown that an endurance limit does exist for HMA mixtures, an established value is yet to be determined, with values varying from 70-400 microstrain (με) based on mixture variability. Traditional FEL vii identification is based on the phenomenological approach, which relates the number of loading cycles to fatigue failure with applied tensile strain and initial stiffness of material. This study determined …

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Predicting Failure Behavior Of Polymeric And Asphalt Composites Using Damage Models, Meghan Vallejo Jul 2012

Predicting Failure Behavior Of Polymeric And Asphalt Composites Using Damage Models, Meghan Vallejo

Civil Engineering ETDs

This study investigates the failure behavior of two types of composite materials using damage models within the framework of ABAQUS finite element software. The failure behavior of an IM7/977-2 carbon epoxy composite material subjected to a Mode I delamination is predicted using traction-separation and bulk material damage models that are based on disturbed state concept (DSC) principles. The models were validated by comparing the results to referenced laboratory testing performed on IM7/977-2 carbon epoxy composite. The damaged states associated with various stages of loading are presented in this study. This study also predicts the failure behavior of asphalt materials through …

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Evaluation Of The Laboratory Resilient Modulus Test Using A New Mexico Subgrade Soil, Anthony Cabrera Jul 2012

Evaluation Of The Laboratory Resilient Modulus Test Using A New Mexico Subgrade Soil, Anthony Cabrera

Civil Engineering ETDs

Resilient modulus (Mr) is a laboratory determined parameter, where a cylindrical specimen is subjected to dynamic axial stresses under confining stresses, while axial deformations are measured. By definition Mr is the ratio of the peak axial stress to the corresponding recoverable axial strain. Currently, there are two accepted laboratory testing protocols for determining Mr, namely AASHTO T 307 and NCHRP 1-28A. These two standards differ from one another in ways that are known to affect Mr, namely in location of load and deformation transducers. One focus of this study is the determination of resilient modulus for an A-6 subgrade soil …

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Data Access And Visualization Benefits From Implementation Of A Hydrologic Information System, Stephen Brown Jul 2012

Data Access And Visualization Benefits From Implementation Of A Hydrologic Information System, Stephen Brown

Civil Engineering ETDs

In 2010, the National Science Foundation (NSF) implemented new guidelines for all scientists applying for grants. A Data Management Plan (DMP) is now required for all proposals in which data are created or gathered while working under the grant. Several organizations have produced templates and applications to assist with the construction of DMPs. The data plans provide a good overview of data processing and storage but do not provide any guidance for managing data during the research process. Large temporal hydrologic data sets can provide a rich insight to complex hydrologic and ecological systems. Complications arise when attempting to query …

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Lattice-Based Peridynamic Modeling Of Linear Elastic Solids, A.S.M. Rahman Jul 2012

Lattice-Based Peridynamic Modeling Of Linear Elastic Solids, A.S.M. Rahman

Civil Engineering ETDs

Concrete is a complex material often used in civil engineering structures. This quasi-brittle material, when reinforced with steel, develops cohesive cracks under loading even though it has adequate strength to carry service loads. Concrete often cracks even before the application of load, due to temperature changes and shrinkage. The displacement field in the structure drastically changes as the cracks initiate and propagate. Thus, concrete fails to satisfy the most fundamental assumptions of continuum mechanics. To overcome the limitations of continuum mechanics, Silling introduced the peridynamic method in 1998. Gerstle and his colleagues generalized the peridynamic model in 2007, introducing the …

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Biosorption Of Uranium And Its Effect On Uranium Transport In Groundewater, Jeanette Leavitt Feb 2012

Biosorption Of Uranium And Its Effect On Uranium Transport In Groundewater, Jeanette Leavitt

Civil Engineering ETDs

In past years, microbial reduction has been explored as a remediation method for uranium-contaminated groundwater at U.S. Department of Energy sites with promising results. Although transport models have been improved to include variations in geochemical concentrations, reductive microbial processes, and adsorption of uranium to minerals, they do not incorporate the presence of microorganisms as sorption sites that may influence the overall transport of uranium. The main objective of this research was to determine the effects of uranium biosorption on the overall transport of uranium by understanding the solution chemical equilibrium and its effects on modeling sorption. This was done by …

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New Generation Fiber Reinforced Polymer Composites Incorporating Carbon Nanotubes, Eslam Soliman Feb 2012

New Generation Fiber Reinforced Polymer Composites Incorporating Carbon Nanotubes, Eslam Soliman

Civil Engineering ETDs

The last five decades observed an increasing use of fiber reinforced polymer(FRP) composites as alternative construction materials for aerospace and infrastructure. The high specific strength of FRP attracted its use as non-corrosive reinforcement. However, FRP materials were characterized with a relatively low ductility and low shear strength compared with steel reinforcement. On the other hand, carbon nanotubes (CNTs) have been introduced in the last decade as a material with minimal defect that is capable of increasing the mechanical properties of polymer matrices. This dissertation reports experimental investigations on the use of multi-walled carbon nanotubes (MWCNTs) to produce a new generation …

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Numerical Analysis Of A Tape Spring Hinge Folded About Two Axes, Bryan Estvanko Feb 2012

Numerical Analysis Of A Tape Spring Hinge Folded About Two Axes, Bryan Estvanko

Civil Engineering ETDs

The ability to fold and unfold large sensor structures in space using hinges is important for space-based sensor technology. Tape spring hinges have become common in deployable space structures due to simplicity, repeatability and unique folding properties. The mechanical response of these hinges (moment-curvature, energy stored etc.) is important in ensuring safety, deployment accuracy as well as optimizing cost of the structure. In an effort to learn more about the folding and deployment properties, finite element software, Abaqus\u2122, was used to analyze a hinge using multidirectional bending. The analysis involved large deformation (rotation through 180 degrees), nonlinear geometric loading. In …

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Selective Fluoride Removal By Aluminum Precipitation & Membrane Filtration, Emily Kowalchuk Feb 2012

Selective Fluoride Removal By Aluminum Precipitation & Membrane Filtration, Emily Kowalchuk

Civil Engineering ETDs

Fluoride is an anionic constituent of most natural surface and ground waters. At low concentrations it has the beneficial effect of improving dental health, but at high concentrations it causes skeletal and other problems. The drinking water standard for fluoride is 4.0 mg/L, but even at this level approximately 10% of exposed children will develop dental enamel fluorosis. Several small communities in New Mexico have source waters with fluoride concentrations higher than 4.0 mg/L. No commercial technologies selectively remove fluoride from drinking water in part because it is relatively non-reactive in aqueous solution and also because its chemistry is similar …

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Clarification Of The Notched Beam Level Ii Testing Procedures Of Aci 446 Committee Report 5, Scott Chapman Feb 2012

Clarification Of The Notched Beam Level Ii Testing Procedures Of Aci 446 Committee Report 5, Scott Chapman

Civil Engineering ETDs

Concrete under tension exhibits a great degree of post-peak non-linearity. Current design codes assume the tensile strength of concrete to be negligible, which is not only a gross oversimplification of the fracture process of concrete in tension, but is also overly conservative. However, research in the field of fracture mechanics has produced models that can accurately predict crack propagation in concrete using fracture parameters determined from testing. One of these models, which is both simple and reasonably accurate, estimates the post-peak tensile behavior of concrete as a bilinear approximation of the softening curve, known as the bilinear cohesive crack model. …

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Characterization Of Traffic Load And Local Calibration Of The Mepdg For New Mexico, Jose Ivan Rodriguez Ruiz Feb 2012

Characterization Of Traffic Load And Local Calibration Of The Mepdg For New Mexico, Jose Ivan Rodriguez Ruiz

Civil Engineering ETDs

In the Mechanistic-Empirical Pavement Design Guide (MEPDG), traffic loading is more complex and precise than in the old AASHTO 1993 Guide. Traffic load in MEPDG is characterized by a larger number of traffic inputs such as Annual Average Daily Truck Traffic (AADTT), traffic growth, traffic directional distribution, lane distribution, vehicle class distribution, hourly distribution, monthly distribution, axle load spectra, number of axles per truck class, traffic wander, speed, and tire pressure. Many of these inputs can only be obtained from Weigh-in-Motion (WIM) data. There are about 15 WIM stations in New Mexico. Data from these WIM sites are evaluated for …

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Analysis Of Coal Combustion By-Product Disposal Practices In An Arid Climate : Leachate Water Quality, Cheryl Parker Feb 2012

Analysis Of Coal Combustion By-Product Disposal Practices In An Arid Climate : Leachate Water Quality, Cheryl Parker

Civil Engineering ETDs

Coal combustion by-products (CCBs), produced from a large power plant in New Mexico, have been disposed of in a nearby coal mine since 1973. These CCBs consist of fly ash, bottom ash, and sludge from the flue gas desulfurization process and have elevated concentrations of hazardous constituents. There is concern that disposal of these materials in an unlined surface mine may cause ground and surface water contamination. This research project focused on determining the leachate characteristics from fresh unburied and old buried CCBs, and investigated the geochemical transformations that occur with time. Samples of CCBs ranged in age from less …

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Empirical Verification Of Modeled Queue Lengths, Gloria Ababio Jan 2012

Empirical Verification Of Modeled Queue Lengths, Gloria Ababio

Civil Engineering ETDs

The purpose of left turn lanes is to separate left-turning vehicles from the through-traffic stream. This tends to increase capacity by adding another lane to the approaches of an intersection and also improves safety and reduces delay. Capacity, delay and operational issues are usually related to a single shared lane between left-turning vehicles and through-vehicles which are expected to be eliminated with an exclusive left turn lane. If left turn queues are not accurately estimated, they may be the source of these safety issues counteracting the benefits of the left turn lane. The accurate determination of left turn queues is …

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Synthesis And Nano-Mechanical Characterization Of Calcium Silicate Hydrate (C-S-H), Emilia Foley Aug 2011

Synthesis And Nano-Mechanical Characterization Of Calcium Silicate Hydrate (C-S-H), Emilia Foley

Civil Engineering ETDs

Calcium Silicate Hydrate (C-S-H) constitutes two-thirds of hydrated cement paste by volume. Having a better understanding of the mechanical properties of C-S-H will significantly aid in future effort for making concrete by design' for specific applications such as blast resistance. C-S-H is an amorphous compound whose chemical structure has been debated by researchers for years. It has been found that C-S-H can form with a wide variety of calcium to silicate (C/S) ratios, and it is the intent of this thesis to determine the effect of the C/S ratio on mechanical properties, most specifically elastic modulus of C-S-H. By varying …

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Short & Long Term Properties Of Self-Consolidating Concrete Incorporating Fly Ash And Local Aggregate, Jacob Hays Aug 2011

Short & Long Term Properties Of Self-Consolidating Concrete Incorporating Fly Ash And Local Aggregate, Jacob Hays

Civil Engineering ETDs

Self-consolidating concrete (SCC) is a high performance concrete that flows under its own weight so that filling forms containing congested reinforcement is possible without mechanical vibration within placements. There has been growing interest to use SCC for precast and prestressed concrete elements. Therefore, it is important to examine the mechanical and durability properties of SCC to gain insights for the design and implementation of SCC in structures. This thesis presents the mechanical and durability experiments used for characterization and acceptance of SCC. Because there are many normally vibrated concretes (NVC) used today for structural applications, comparisons between the mechanical and …

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Fracture Toughness Of Ultra High Performance Concrete, Ebadollah Honarvar Gheitanbaf Aug 2011

Fracture Toughness Of Ultra High Performance Concrete, Ebadollah Honarvar Gheitanbaf

Civil Engineering ETDs

In this study, fracture properties of Ultra-High Performance Concrete (UHPC), and High Performance Concrete (HPC) are presented. The average compressive strengths of UHPC and HPC used in the tests were 141 MPa, and 55 MPa respectively. Formulation and processing of the mixes and test specimens are also presented. Size effect and the influence of compressive strength of concrete on fracture parameters were investigated using test methods recommended by ACI Committee 446. The fracture properties investigated included crack opening displacement (COD), fracture energy GF, fracture toughness KIC, and bilinear approximation of the softening curve, for two different sizes of UHPC and …

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Strengthening Reinforced Concrete Slabs Using A Combination Of Cfrp And Uhpc, Andrew P. Garner Aug 2011

Strengthening Reinforced Concrete Slabs Using A Combination Of Cfrp And Uhpc, Andrew P. Garner

Civil Engineering ETDs

Reinforced concrete (RC) structures are widely used in construction. Due to aging infrastructure, increased loads, and inadequate maintenance, RC structures need to be retrofitted for prolonged lifespan and increased capacity. Traditional methods of strengthening involve the installation of fiber reinforced polymer (FRP) composites to the tension side of structures. This can be problematic in practice because of the difficulty in accessing the underside, the tension side, of the structural member. In addition, traditional strengthening techniques typically result in exposing the FRP to the external environment with possible degradation and other environmental effects. This research investigates an innovative method to strengthen …

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Applying Numerical Sediment Transport Models To Examine River Restoration Sustainablilty At The Rio Grande Nature Center, New Mexico, Kyle Shour Aug 2011

Applying Numerical Sediment Transport Models To Examine River Restoration Sustainablilty At The Rio Grande Nature Center, New Mexico, Kyle Shour

Civil Engineering ETDs

Much of the Middle Rio Grande has severely degraded since 1930 when flood control institution began (Scurlock 1998). Since that time, additional anthropogenic stressors have continued to cause the river to incise and narrow and have harmed the ecological health of the system. As a result, many different entities have developed restoration projects along the Middle Rio Grande. These projects are often localized, small scale features that promote native vegetation establishment and improve habitat for endangered species without removing flood protection measures. One such feature is the Rio Grande Nature Center (RGNC) Habitat Restoration project. The project consists of removing …

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Command Vs. Self-Regulation In Construction Safety : A Case Study Of Chase, Amelia Scharrer Aug 2011

Command Vs. Self-Regulation In Construction Safety : A Case Study Of Chase, Amelia Scharrer

Civil Engineering ETDs

According to the Bureau of Labor Statistics in 2009 there were 816 fatal injuries in the United States in the construction industry. Reducing injuries and fatalities on construction sites is good for workers, contractors, and owners. The Occupational Health and Safety Administration (OSHA) was created to ensure safe and healthful working conditions for all working men and women. In order to achieve this goal OSHA has been setting and enforcing standards with a command-and-control' system, outreach, education and assistance. However, incidents still occur on construction sites. The gaps within the 'command-and-control' system have lead researchers and industry to look at …

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Application Of Hec-Hms 3.4 In Estimating Streamflow Of The Rio Grande Under Impacts Of Climate Change, Chi Bui Aug 2011

Application Of Hec-Hms 3.4 In Estimating Streamflow Of The Rio Grande Under Impacts Of Climate Change, Chi Bui

Civil Engineering ETDs

The Rio Grande originates from the San Juan Mountains of southern Colorado, and flows year-round south through the entire length of New Mexico. It has an approximate drainage area of 1.9 million acres in New Mexico (USGS 1996), and provides habitat for diverse wildlife along the river, including the silvery minnow, an endangered indicator species. The hydrology of the river is characterized by low flow during the winter months, a snow-induced peak in spring/early summer, and smaller peaks in July and August due to the effect of the monsoon season. In the five recent decades, the Rio Grande has experienced …

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Creep And Fracture Of Self-Consolidating Concrete Incorporating Fly Ash, Rick Grahn Aug 2011

Creep And Fracture Of Self-Consolidating Concrete Incorporating Fly Ash, Rick Grahn

Civil Engineering ETDs

Self-consolidating concrete (SCC) is a relatively new type of concrete that has the ability to flow under its own weight such that it can pass through tightly spaced reinforcement and fill corners of molds without the use of mechanical vibration. Due to the favorable plastic properties of SCC, there has been an increased interest in using SCC in precast and pre-stressed bridges. However, SCC achieves this flowability by reducing the maximum aggregate size in the concrete mix, significantly increasing the volume of the cement paste and incorporating large content of powder fillers. This mix design of SCC was hypothesized to …

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Acoustic Bandgap Sensors For Hot-Spot Damage Monitoring, Ryan Schnalzer Aug 2011

Acoustic Bandgap Sensors For Hot-Spot Damage Monitoring, Ryan Schnalzer

Civil Engineering ETDs

This research presents a novel, mechanically tunable sensor that utilizes the acoustic response of a polymer based acoustic bandgap (ABG) material to identify and quantify damage in material substrates. Acoustic bandgap (ABG) sensors are the mechanical analogues of semi-conductors by which a periodic array of differing acoustic impedances causes an acoustic bandgap. This is comparable to the periodic array of electronic potentials that cause an electronic bandgap in semi-conductors. An ABG sensor is composed of a host matrix material with a periodic array of inclusions/scatterers made of a material with dissimilar acoustic impedance. ABG sensors offer advantages to structural health …

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Using Vibration-Based Monitoring To Detect Mass Changes In Satellites, Breck Vernon Aug 2011

Using Vibration-Based Monitoring To Detect Mass Changes In Satellites, Breck Vernon

Civil Engineering ETDs

Vibration-based structural health monitoring could be a useful form of determining the health and safety of space structures. A particular concern is the possibility of a foreign object that attaches itself to a satellite in orbit for adverse reasons. A frequency response analysis was used to determine the changes in mass and moment of inertia of the space structure based on a change in the natural frequencies of the structure or components of the structure. Feasibility studies were first conducted on a 7 in x 19 in aluminum plate with various boundary conditions, which was impacted with a mallet and …

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Ground Water-Surface Water Interaction Of Rio Grande Biopark Area, Albuquerque, New Mexico, Sadia Faiza Jul 2011

Ground Water-Surface Water Interaction Of Rio Grande Biopark Area, Albuquerque, New Mexico, Sadia Faiza

Civil Engineering ETDs

Ground water and surface water are typically considered as separate entities, but all surface water features interact with ground water in different ways. Better understanding of ground water-surface water interaction is important for effective land and water management. This study investigated the impact of surface water on ground water levels as well as soil moisture content in a small region of Albuquerque Biopark near the Rio Grande. This study involved collection of field data on soil moisture, ground water levels and observations of vegetation densities adjacent to the Biopark wetlands. Numerical models were developed of the influence of the river …

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Parallel Simulation Of Reinforced Concrete Sructures Using Peridynamics, Navid Sakhavand Jul 2011

Parallel Simulation Of Reinforced Concrete Sructures Using Peridynamics, Navid Sakhavand

Civil Engineering ETDs

The failure of concrete structures involves many complex mechanisms. Traditional theoretical models are limited to specific problems and are not applicable to many real-life problems. Consequently, design specifications mostly rely on empirical equations derived from laboratory tests at the component level. It is desirable to develop new analysis methods, capable of harnessing material-level test parameters. To overcome limitations and shortcomings of models based on continuum mechanics and fracture mechanics, Stewart Silling introduced the concept of peridynamics in 1998. Similar to molecular dynamics, peridynamic modeling of a physical structure involves simulating interacting particles subjected to an empirical force field. The evolution …

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Hydraulic And Geospatial Analyses Of Stream Engineering And Habitat Restoration Near Los Lunas, Nm, Stephen Kissock Jul 2011

Hydraulic And Geospatial Analyses Of Stream Engineering And Habitat Restoration Near Los Lunas, Nm, Stephen Kissock

Civil Engineering ETDs

Stream restoration is a complex process encompassing multiple disciplines and organizations to achieve specific, immediate and long-term goals. Analyses of many completed projects are limited to narrow objectives that commonly exclude the same broad scopes envisioned during the planning process. This thesis studies one completed habitat restoration project in terms of its engineering and biological sustainability using geospatial analysis procedures not widely applied to these goals. These procedures include adjustment of a digital terrain model for hydraulic accuracy, the use of the digital terrain model and aerial imagery for the digitization of features used in hydraulic modeling, and the geospatial …

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Nano-Scale Evaluation Of Moisture Damage In Asphalt, Md Arifuzzaman Feb 2011

Nano-Scale Evaluation Of Moisture Damage In Asphalt, Md Arifuzzaman

Civil Engineering ETDs

Moisture damage is one of the major problems of asphalt pavements in United States. The moisture damage problem in asphalt has been studied for decades; still it remains an unsolved problem. Traditional macro-scale tests and methods failed to describe how and what factors affect moisture damage because moisture damage in asphalt is related to asphalt chemistry and adhesion characteristics, which are below micron scale phenomena. To this end, asphalt chemistry and adhesion values are studied at nano-scale to understand moisture damage in this study. Nano-scale measurements are conducted using an Atomic Force Microscope (AFM) in the laboratory. In an AFM …

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Tree Root Encroachment On Levee Drainage System, Tomomi Ito Feb 2011

Tree Root Encroachment On Levee Drainage System, Tomomi Ito

Civil Engineering ETDs

The objectives of this study were to estimate the influence of roots on the drainage facilities associated with the levees along the middle Rio Grande (MRG), and to suggest an appropriate drainage design. This study consists of three research elements: (1) GIS-based analysis in estimating root distribution along levees, (2) a bench-top experiment, and (3) evaluating a drainage designs using a numerical model. First, tree crown sizes were measured on GIS-based aerial photography to estimate root distributions. The results were compared with vegetation maps that were created based on field observations. The GIS-based measurements and field measurements showed similar values …

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Rheological And Nanomechanical Characterization Of Aging In Polymer Modified Asphalt, Seyed Saleh Yousefi Feb 2011

Rheological And Nanomechanical Characterization Of Aging In Polymer Modified Asphalt, Seyed Saleh Yousefi

Civil Engineering ETDs

In this study, change in rheological and nanomechanical properties of asphalt due to aging is determined in the laboratory. Asphalt binders are aged using Rolling Thin Film Oven (RTFO), Pressure Aging Vessel (PAV), and draft ovens. Asphalt binder includes an unmodified base binder, Styrene-Butadiene (SB) and Styrene-Butadiene-Styrene (SBS) polymer modified binders. Rheological properties such as viscosity, phase angle, shear modulus, creep compliance, stiffness, etc. are determined using Dynamic Shear Rheometer (DSR) test, Multiple Stress Creep Recovery (MSCR) test, Bending Beam Rheometer (BBR) test, Rotational Viscosity (RV) test and the Direct Tension (DT) test. Nanomechanical properties such as hardness and reduced …

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Sensitivity Of Mepdg Using Advanced Statistical Analyses, Nasrin Sumee Feb 2011

Sensitivity Of Mepdg Using Advanced Statistical Analyses, Nasrin Sumee

Civil Engineering ETDs

Recently, pavement design has changed from old method based on empirical relation to a new method called Mechanistic Empirical Pavement Design Guide (MEPDG). It is essential to perform a detailed sensitivity analysis of MEPDG outputs to input variables. In particular, MEPDG inputs need to be classified based on their influence on MEPDG outputs for New Mexico pavement conditions. In this study, sensitivity analyses are performed to identify a list of input variables that have significant impacts on the MEPDG outputs considering New Mexico pavement conditions. Sensitivity analyses are performed in two steps. In the first step, a preliminary sensitivity analysis …

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