Engineering Commons^™

Physical And Stochiometric Controls On Nutrient Uptake And Ecosystem Respiration In Contrasting Sites, Jancoba K. Dorley

Civil Engineering ETDs

Meteorological, hydrological, and biogeochemical processes naturally control stream ecosystems. These processes define the frequency and distribution of precipitation and the supply and demand of solutes and particles to support aquatic food chains through space and time. Studies have also found that stream ecosystems are also controlled by anthropogenic activities, which occur on a much shorter timescale. These anthropogenic activities affect stream ecosystems' structure and function from local to planetary changes to the environment. It is essential for scientists and engineers to understand the relationships between naturally occurring processes and those created by human activities for a better interpretation of stream …

Early-Age Strength And Failure Characteristics Of 3d Printable Polymer Concrete: Numerical Modelling And Experimental Testing, Mohammad Amin Dehghani Najvani

Civil Engineering ETDs

The time-dependent rheological and early-age strength parameters of Polymer concrete (PC) were investigated. PC flow decreased, and the static yield stress and thixotropy increased as the specimen aged, while the dynamic yield stress remained unchanged. The study found that the Herschel-Bulkley model can accurately describe the PC’s rheological behavior over time. The change in cohesion strength and internal friction angle over time was observed using uniaxial unconfined compression and direct shear tests of fresh PC. A time-dependent MohrCoulomb failure criterion was established. Temperature analysis was used to determine the gel time and explain the evolution of the time-dependent early-age strength …

Modeling Of Asphalt Concrete For Cross-Anisotropic Visco-Elasticity And Heterogeneity, Zafrul Hakim Khan

Civil Engineering ETDs

Asphalt Concrete (AC) is a cross-anisotropic viscoelastic material. This study has developed a methodology to backcalculate the cross-anisotropic properties of the AC layer from the Falling Weight Deflectometer (FWD) sensor and pavement response data from embedded sensors inside a pavement section. This study has also developed a two-way coupled Multiscale Finite Element Model (MsFEM) with Phase Field Fracture (PFF) to study the microstructural heterogeneity and damage of the AC layer based on the actual field loadings. A Finite Difference Time Domain (FDTD) and Machine learning-based backcalculation algorithm were developed to determine the layer thickness and dielectric constant from air-coupled Ground …

Performance Evaluation Of E-Ticketing Technologies On Asphalt Paving Projects In New Mexico, Gena C. Robertson

Civil Engineering ETDs

The collection and processing of paper tickets for construction material delivery is an inefficient and antiquated practice that exposes inspectors on highway paving projects to substantial safety risks. An alternative to the collection of paper tickets is e-Ticketing, which uses web-based systems to deliver similar information. This research documented a current paper ticketing process and compared it to an e-Ticketing process that was implemented on several pilot projects. Data were obtained using stakeholder meetings, personnel interviews, and surveys. When compared to a paper ticketing system, e-Ticketing was shown to have fewer opportunities for error, require fewer decision points, and provide …

Additive Manufacturing Of Engineered Cementitious Composites With Ultra-High Tensile Ductility, Amir Bakhshi

Civil Engineering ETDs

One of the critical factors in the development of additive manufacturing in the construction industry is designing suitable materials for 3D printing applications. 3D concrete printing (3DCP) has gained significant attention due to the abundance and availability of concrete. However, concrete is a brittle material and, without proper reinforcement, cannot meet the requirements for structural purposes. Engineered Cementitious Composites (ECC), known for high ductility, and strain-hardening with low fiber contents, can potentially eliminate the need for steel reinforcement in 3D printing without any need for manual placement of reinforcement. A set of systematic tests on ECC mix designs' fresh and …

Measurement Of Resilience Performance For Infrastructure Construction Project Delivery, Fei Han

Civil Engineering ETDs

In the past decade, infrastructure resilience in the U.S. has become critical due to increasing disruptions to the built environment and the resultant consequences on economic, social, and environmental goals. This attention to resilience research is drawn to investigating the ability of existing structures and facilities to resist and recover from natural and human-caused hazards. From a broader view, resilience also applies to processes, such as infrastructure project delivery processes. During these processes, a project often suffers inevitable threats and disruptions, which can significantly delay or derail the project if the process is not resilient.

This research aimed to conceptualize …

3d Printed Concrete & Polymer Concrete For Infrastructure Applications, Daniel Heras Murcia

Civil Engineering ETDs

Additive manufacturing technology has been established as one of the fastest-growing building technologies worldwide. Three-dimensional concrete printing (3DCP) has developed an increasing interest in the last decade due to its prospects as a transformative technology for industries such as the concrete precast. Besides the improvements in automation technologies in construction, traditional construction has faced considerable challenges: high accident rates, labor dependency, significant potential for automation, and high costs associated with the use of traditional formwork. In this context, three-dimensional concrete, also referred to as physical prototyping, is a novel construction technique in which the concrete is extruded layer-to-layer. 3DCP is …

Dynamic Hvac Energy Management Using Commercial Building Occupancy Metrics & Neural Networks, Krishna Chaitanya Jagadeesh Simma

Civil Engineering ETDs

With the rise of technology use in buildings, it is now possible to collect data that can be used to improve building energy consumption. One factor that has significant impact on building energy consumption is occupancy. Recent studies have shown promising results in obtaining occupancy information from existing infrastructure such as WiFi router networks. However, these existing frameworks require additional investments through software upgrades, added infrastructure, computational resources, and may raise occupant privacy concerns. Additionally, with occupant thermal comfort statistics being lower than ASHAREA specified standards, a novel approach for indoor climate control is needed. To address the limitations in …

A Practical Methodology To Detect, Quantify And Characterize Experimental Uncertainties In The Dynamic Testing Of Structures, James L. Woodall

Civil Engineering ETDs

This thesis investigates the uncertainty in the experimental context of structural dynamics. This thesis proposes a method to estimate both the effect of boundary conditions, as well as two different methods to detect the location of sensors on a specimen. Firstly, this thesis proposes a technique to predict the dynamic behavior of any point along a cantilever beam with an uncertain transverse elastic restraint. Secondly, this thesis investigates the estimation of the location of a sensor given the output data of a physical experiment with two different methods. Small errors in the sensor location may go unnoticed in the frequency …

Evaluating Public Transit Accessibility In Albuquerque, New Mexico: A Fixed-Route Bus Service Analysis, Risa E. Gutierrez

Civil Engineering ETDs

This research analyzed how residential accessibility to fixed-route bus service in Albuquerque, New Mexico varies by distance, income level, and headway. A literature review investigated components of travel that might deter people from using public transit such as travel distance, sidewalk condition or availability, bus headway, lack of active travel in today’s society, personal and traffic safety, and access equity. Geographic Information System (GIS) mapping was used to determine if low-income neighborhoods have better or worse access to ABQ Ride bus stops relative to medium- or high-income neighborhoods. Residential land use was divided into three economic classes based on 2018 …

Post-Wildfire Geomorphic Stream Response In Six New Mexican Watersheds, Aljaz Praznik

Civil Engineering ETDs

Wildfire causes severe physical changes to watersheds, which then leads to geomorphic changes in the burned watersheds. In New Mexico and the southwestern U.S., flooding is a common response after a wildfire, due to higher water runoff from the hillslopes and sediment erosion rates. These flood events change the erosion and deposition characteristics of a stream, which can result in the deposition of a large amount of sediment near the communities living downstream. The objective of this research was to analyze and compare post-fire geomorphic stream response caused by six different wildfires in New Mexico with the goal to create …

The Development Of A Novel Experiment On Confined, Flattened Brazilian Disks To Correlate Damage And Permeability In Brittle Geo-Materials, Samuel H. Boyce

Civil Engineering ETDs

This research develops a novel experiment using flattened Brazilian disks under confining pressure with concurrent permeability measurements and acoustic emission monitoring. The purpose of this work is to correlate damage and permeability in brittle geo-materials. Two series of tests are performed on concrete and one series on tuff, under a range of confining stresses between 2.76 and 13.79 MPa. Tests were continued beyond peak stress conditions, capturing data in the post-peak region. The acoustic emission data (cumulative energy and counts) are used to identify damage thresholds and track the progression of microscopic damage. This quantified damage is then correlated to …

Application Of Cation Exchange And Nanofiltration To Treat Flue Gas Desulfurization Wastewater, Ayush R. Shahi

Civil Engineering ETDs

Flue gas emitted from coal-fired power plants is one of the major sources of sulfur and nitrogen oxides emissions to the atmosphere in the world today. Although coal use has decreased, it is still a major contributor to such emissions. The Clean Air Act in the United States established regulations for coal-fired power plants to limit SO_x and NO_x emissions into the atmosphere. To meet regulatory requirements, power plants have been using scrubbers to limit their air emissions. Flue-gas desulfurization (FGD) is a pollution prevention method that is employed to limit sulfur dioxide emissions directly in the environment …

Is Transportation Planning Effective? A Critical Review Of Long-Range Regional Transportation Planning In The United States, Razieh Nadafianshahamabadi

Civil Engineering ETDs

The Federal-Aid Highway Act requires urban areas with a population greater than 50,000 to create Metropolitan Planning Organizations (MPOs) to ensure that funding for transportation projects and programs are based on a continuing, cooperative, and comprehensive planning process. A major responsibility of each MPO is the creation of a long-range transportation plan (LRTP) that addresses the transportation needs of a metropolitan region over the next twenty years or more. While long-range regional transportation planning goals have grown to include a wide range of concerns and technical methods for evaluating planning scenarios have advanced substantially over the past 50 years, there …

An Engineered Fit-For-Purpose Polymer Nanocomposite Seal Repair Material For Wellbores, Moneeb Genedy

Civil Engineering ETDs

Seal integrity of wellbores has become of significant interest due to repeated leakage and spill incidents occurring worldwide that jeopardize both human health and the environment in addition to causing significant economic burden. This is attributed to the fact that wellbores intersecting geographical formations contain potential leakage pathways. The cement-steel and cement-rock formation interfaces are recognized as two critical leakage pathways.

A seal repair material that has good bond strength with both steel and rock formations in addition to the ability to completely fill thin microcracks is needed to restore the seal integrity of wellbores. In this research, engineered polymer …

Modeling And Simulation Of Damage In The Brazilian Indirect Tension Test Using The Finite-Discrete Element Method, Jeremiah C. Leyba

Civil Engineering ETDs

The Brazilian indirect tension test is used to investigate possible correlations between progressive damage and associated permeability changes. The test offers ease of replicability with a damage behavior known to lead to fracture openings as a tool for interpreting the indirect tensile strength of concrete and rocks. This behavior can lend insight into the nature of tensile damage and fracture progression in association with changes in permeability. The nature of these brittle materials is known to exhibit rapid failures in the Brazilian indirect tension test and require a method to retard the progression of damage for the possibility of acquiring …

Understanding Asphalt Concrete Aging Using Nanoindentation, Hasan M. Faisal

Civil Engineering ETDs

Asphalt concrete (AC) is created by mixing liquid asphalt binder with solid aggregates. When asphalt binder is mixed with aggregates, it creates a thin film (about 7-16 microns thick) around the aggregate surface. Fine aggregate (smaller than 0.075 mm size) get entrapped within the binder film or mixed with the binder, and create a phase called mastic. Both asphalt film and mastic play significant roles in aging of asphalt pavement. To this day, tests were performed mainly on the bulk liquid asphalt, but not on the film or mastic. In this study, for the first time, nanoindentation tests were done …

Characterization And Modeling Of Asphalt Concrete For Dynamic Properties And Performances, A S M A. Rahman

Civil Engineering ETDs

The recently developed mechanistic-empirical pavement design guide (MEPDG, also known as Pavement M-E design method) uses the nationally calibrated, binder viscosity-based dynamic modulus predictive model for the design and analysis of asphalt pavements. In this study, this model is assessed for its appropriateness for asphalt-aggregate mixtures typically used in New Mexico. In essence, this study investigates the predictability issue of complex modulus of New Mexico mixes. A total of 54 Superpave mixes with different aggregate gradations, air voids, and binder grades were collected from the mixing plants and from the pavement construction sites. The loose asphalt mixtures were then compacted, …

Characterization Of Asphalt Healing And Incorporation In A Fatigue Damage Model, Umme A. Mannan

Civil Engineering ETDs

Healing is defined as the restoration of the material property during the rest period after damage. The healing property of the asphalt binder is opposite to fatigue damage, which occurs due to repeated traffic loading. On the other hand, healing occurs in the rest period between loading. Most of the existing methods for characterizing the fatigue damage and healing of asphalt are empirical in nature and do not consider the mechanism of healing. Although the asphalt concrete is a mixture of asphalt binder, fines and aggregates, most of the healing occurs in the asphalt binder. Therefore, it is important to …

Characterization Of Unknown Bridge Foundations, Saman Rashidyan

Civil Engineering ETDs

The National Bridge Inventory (NBI) recognized 86,133 bridges in the United States have no foundation data on record in 2003. It is evident that an unknown percentage of the 86,133 bridges identified by NBI with missing foundation data could also be highly vulnerable to scouring induced by water flow coupled with erodible soils. Conventional excavation, coring and boring excavations to identify unknown bridge foundation depths and types are deemed to be expensive, destructive, and limited in their application to the unknown foundation problem. Many surface and borehole nondestructive testing (NDT) technologies have been developed for this purpose. Three economical proven …

Viscoelastic Effects In Carbon Fiber Reinforced Polymer Strain Energy Deployable Composite Tape Springs, Elisa C. Borowski

Civil Engineering ETDs

Strain energy deployable composite structures are of great importance to the aerospace community due to their light weight, high stiffness, impressive flexibility, compact stowage configuration, and ability to self-deploy. These attributes make composite deployable hinges ideal for aerospace applications that can benefit from decreased payload and decreased structural complexity through a reduction in deployment parts. However, successful application of these deployable structures requires an in-depth understanding of their mechanical behavior throughout stowage and deployment processes. Upon release from a high strain stowage configuration, high deployment accelerations caused by a great amount of stored strain energy could potentially damage the structure …

Mechanical Characterization Of Polymer Concrete With Nanomaterials, Alaeddin Douba

Civil Engineering ETDs

Nanomaterials are defined by those whose characteristic length scale lies within the nanometer scale. Their extreme dimension achieves extraordinary mechanical properties superior to other micro and macro additives. The introduction of nanotechnology to Civil Engineering utilizes low volume inclusions of nanomaterials to alter the properties of conventionally used bulk materials. Polymer Concrete (PC) where epoxy polymer binders replace cement binders, has become a common repair material among many other application and often can be considered an alternative to Portland cement concrete (PCC). PC is often used in bridge deck overlays, manholes, machine foundations and repairs. Its diverse chemical composition and …

Comprehensive Silica Removal With Ferric Compounds For Industrial Wastewater Reuse, Ehren D. Baca

Civil Engineering ETDs

Cooling towers, integrated circuit (IC) manufacture and reverse osmosis (RO) generate copious amounts of wastewater high in colloidal and reactive silica inhibiting on-site or synergistic reuse. Silica present in cooling water can reach solubility limits via evaporation and form impervious scale on heat transfer surfaces that decreases efficiency. When water is treated by RO operating at high rejection, silica forms difficult-to-remove scale on the membrane feed side in the form of glassy patches and communities of aggregate particles, inhibiting aspirations for zero liquid discharge. Current methods for silica scale mitigation include abundant dosing with chemical antiscalents or complex operating schemes. …

Practical Considerations In Determining Timber Pile Depth Using The Sonic Echo Method, Ali F. Jwary

Civil Engineering ETDs

The Federal Highway Administration indicates that about 85,000 bridges in the United States have no original contract documents with information about the type, depth, geometry and material of their foundations (FHWA, 2010). Furthermore, the National Bridge Inventory (NBI) provides information about 86,133 bridges nationwide that are rated as scour critical because of unknown foundation condition. In New Mexico, there are more than 281 bridges with unknown foundations, which are owned by the New Mexico Department of Transportation; 71 of these are timber bridges. These data indicate a serious problem that needs decisive action to assess the unknown bridge foundation characteristics …

Input Parameters In Discrete Element Modeling, Seyedali Yousefi

Civil Engineering ETDs

The discrete element method (DEM) is employed to study complex behaviors of particulate media. Input parameters may greatly affect the response of DEM models and should therefore be selected carefully. Scaling techniques are employed to enlarge prohibitively small time-steps. To study these techniques, dimensionless input parameters were defined. Responses of models in the dimensionless scale were invariant with choice of density, elastic modulus, and characteristic length if the dimensionless parameters were kept constant. Hence, density scaling is equivalent to use of a higher strain-rate, and stiffness scaling results in a higher strain-rate and an elevated stress state in the dimensionless …

Understanding The Behavior Of Embankment Dams Under Blast Loading, Courtney L. Busch

Civil Engineering ETDs

This purpose of this study is to investigate the deformation-induced stability of earthen embankment dams to explosive airblast loading. This study specifically investigated the effects of close-in explosive airblast loads on the downstream toe of a homogeneous earthen embankment dam composed of cohesive soils. Small-scale explosive airblast experiments were performed on cohesive soils to obtain an experimental data set with which to compare numerical analyses. Experimental measurements included crater geometry, ground vibration energy, and air overpressure from the blast events. Laboratory tests were conducted on the experiment soils to obtain engineering properties including shear strength and compressibility indices. Finite element …