Engineering Commons^™

Application Of Biochar As Beneficial Additive In Concrete, Temirlan Barissov

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Biochar is a high-carbon solid material produced via thermal decomposition of organic biomass in a low-oxygen environment. Characterized with high water retention properties and high alkalinity, biochar is generally used for soil amendment and fertilization purposes. This study is intended to explore the feasibility of using biochar as a beneficial additive of the most used manmade material, concrete. Literature review revealed several studies where biochar was successfully implemented as an additive in concrete. The beneficial influence of biochar on the mechanical characteristics of concrete is based on nucleation and densification effects. However, the internal microstructure, porosity and chemical composition of …

Modeling Watershed Sensitivity To Climate Change In Systems Affected By Discharge Of Mine Tailings, Johnette C. Shockley

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

For more than a century, a large volume of gold-mining tailings was deposited in Whitewood Creek and the Belle Fourche River, tributaries to the Cheyenne River in western South Dakota. Much of it still remains, and field and historical evidence indicates continued remobilization of tailings-containing alluvium in these bedrock-dominated channels. Both long-term, natural fluctuations in climate and anthropogenically driven changes can impact regional precipitation, temperature, hydrologic patterns, and ecosystem functions. Such changes have the potential to affect both the transport and distribution of arsenic-laden sediments and mechanical erosion that can undermine the stability of channel-bed and overbank material.

This study …

Probabilistic Seismic Vulnerability Assessment Of Freestanding Historic Monuments, Marie E. Wagner

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Seismic events can cause significant damage to structures, especially to freestanding structures which are not fixed to the ground and are free to rock independently. This thesis will study the response of freestanding statues and monuments to ground motions and develop probabilistic models for overturning, in order to assist in retrofitting and repair efforts. To do this, single and dual block system models were created with a variety of sizes, aspect ratios, and asymmetries, then subjected to several historic ground motions to determine whether they overturn using three-dimensional distinct element analysis as a result of rocking, sliding or twisting in …

Prioritization Of Research On Bridge Railings For Use On Timber Deck Bridges And Development Of Two Glulam Bridge Railing Systems, Jared Duren

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

In the past, many timber bridge railings, bridge railings for use on timber deck bridges, and approach guardrail transition systems to accompany these railings, have been developed to meet different impact safety criteria. Through an extensive literature review, the design details of these systems were identified and organized. A survey was then developed and distributed to multiple government agencies and timber industry members to identify their desire for these bridge railing and approach guardrail transition systems to be developed to meet current American Association of State Highway and Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) impact safety criteria. …

Establishing Safe Operating Speeds For Autonomous Vehicles: A Case Study From The Automated Skyway Express In Jacksonville, Florida, Andrew Loken

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Autonomous vehicles (AVs) differ significantly from traditional passenger vehicles in both their behavior and physical characteristics. As such, the validity of the guidance provided in the Manual for Assessing Safety Hardware, Second Edition (MASH 2016) is questionable in AV applications. Impact conditions specified in MASH 2016 are inextricably linked to the traditional vehicles underlying the estimates. For AV applications, conditions must be estimated from the ground up, stepping outside the guidance of MASH 2016. Herein, a method for evaluating existing infrastructure to support AV traffic is proposed. The method integrates traditional structural analyses with unconventional methods of estimating impact conditions. …

Determinants Of Water System Management, Caleb White

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Water system management is complex, involving state, local, and federal regulations and impacting people from a wide variety of socioeconomic backgrounds. Systems in the developing and industrialized worlds both face challenges in managing water systems. Much research has been completed regarding associations of water system violations and system factors, and there has been an increased attention to issues of environmental justice – how water system violations affect communities of color, impoverished communities, and rural communities. Currently no studies have focused on the associations between socioeconomic factors and water system management violations. The goal of this research was to ascertain the …

Fragility Functions Of Manufactured Houses Under Earthquake Loads, Shuyah Tani Aurore Ouoba

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Manufactured homes are factory-built homes made of wooden structural members, then transported and installed on a given site. Manufactured housing is used in many countries, such as in Australia, and in New Zealand but remain mostly popular in the United States. In 2020, nearly 22 million people were estimated to live in manufactured homes in the United States, with an increase of more than fifty percent in the shipment over the past seven years. However, performance observations from the last decades have shown the vulnerability of manufactured homes to extreme events, like windstorms and earthquakes. Damage assessments and post-event evaluations …

Risk And Safety Associated With Hazardous Materials Transport In Rural And Native American Communities: A Case Study Of Thurston County, Nebraska, Sydney James

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Rural counties and Native American Reservations often lack the resources and planning to respond to a hazardous material release which can cause catastrophic results. Many rural counties and Native American Reservations do not have close access to a fire department or medical facility, which would increase response times during a time of crisis. Jurisdiction issues further complicate the matter since Native American Reservations are sovereign nations,.

Thurston County, home to two Native American Reservations, served as a case study to perform a safety analysis for vehicles transporting hazardous material. Stakeholders within the county from tribal, county, and state levels were …

A Methodology For Estimating Capacity And Passenger Car Equivalents For Connected And Automated Vehicles Traveling On Freeways, Antonio Hurtado Beltran

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Recently, there has been a significant amount of research related to heavy trucks operating as connected and autonomous vehicles (CAVs). In order to understand the potential impact on the freeway system of CAV technologies, analyses should be conducted using the standard US methodological framework. In the current version of the Highway Capacity Manual (HCM-6), equal-capacity passenger car equivalencies (EC-PCEs) are used to account for the effect of heavy trucks on capacity and quality of service analyses. It is argued in this dissertation the HCM-6 EC-PCE methodology for basic freeway and multilane highway segments can be used to explore a wide …

Evaluation Of Permanent Concrete Barriers To Mash 2016, Samuel Elias Hovde

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The objective of this research project was to develop evaluation criteria for permanent concrete barriers to MASH 2016 TL-3 and TL-4 without crash testing and then to evaluate permanent concrete barrier standards provided by the sponsoring agencies of the Midwest Pooled Fund Program. A literature review was conducted to determine evaluation criteria for stability, shape, strength, and anchorage, and a database of permanent concrete barrier crash tests was compiled. A survey was conducted to collect barrier standards from the members of the Midwest Pooled Fund Program, and barriers were selected and evaluated according to the determined methodology. A total of …

Impact Of Particle Surface Charge Heterogeneity On Deposition Onto Flat Surfaces And Transport In Porous Media, Thompson Delon

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Biological and non-biological natural colloids are anisotropic and ubiquitously exist in groundwater. Previously in colloid transport modelling, colloids are assumed to be homogenous for simplification, whether in shape or surface charge. More research has been done to incorporate surface heterogeneity in the transport experiment, i.e., surface charge heterogeneity on collector in column experiment. However, few studies have been done on surface heterogeneity on colloids themselves.

In this dissertation, Janus particles with different surface charge was developed to model surface heterogeneity on colloids. The interaction energy between Janus particle and flat surfaces was analyzed through DLVO simulation. It was discovered that …

Hydraulic And Mineralogical Characterization Of Organoclay Before And After Reaction With Non-Aqueous Phase Liquid (Napl), Mostafa Afzalian

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Sediment capping—a method used to stabilize and remediate contaminated subaqueous sediment in lakes or river shores by covering the contaminant with multiple layered materials— is a more effective, economic, and durable in situ treatment compared to ex situ methods such as dredging. The caps are typically composed of porous geomaterials such as gravels, sands, Reactive Core Mat (RCM), including reactive soils (e.g., organoclay) and geosynthetics (e.g., geotextiles). The designed caps are regarded as water-permeable so as not to disturb the sediment; however, the caps become unsaturated state because of trapped gas generated from the decomposition of organic matter. Most of …

Concentration And Treatment Of Odors Generated By Landfills, Gabriel Cohen

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Landfills produce hydrogen sulfide (H₂S), an odorous compound that can be a nuisance and danger to public. Biological treatment, in particular bio-trickling filters, is a method for controlling H₂S emissions but startup costs can be costly. The goal of this study is to provide a low-cost method for improving environmental air quality in Nebraska through an odor control device. This study determined that the Loup Central Landfill located near Elba, NE would be an adequate site for the testing and implementation of the odor control device. The off-gas of the Loup Central Landfill was tested for …

Quantitative Assessment Of Alkali-Silica Reaction In Small And Large-Scale Concrete Specimens Utilizing Nonlinear Acoustic Techniques, Clayton Malone

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Nonlinear resonance techniques have been shown to be sensitive to microcracking in materials, including alkali-silica reaction (ASR) damage in concrete. However, application of nonlinear resonance tests have been limited due to the difficulty of application to large-scale field structures and the inability to quantitatively relate material nonlinearity with damage development. In this study, the development of ASR in concrete prisms and large concrete beam specimens of varying aggregate types and specimen sizes was monitored using linear and nonlinear resonance techniques.

For the concrete prisms, although the linear resonance frequency test could detect initiation and development of ASR damage in specimens …

Biofiltration Of Volatile Organic Compounds Emitted At Ethanol Plants, Mitham Al-Faliti

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Ethanol is a major biofuel source of energy in the U.S. Ethanol production produces several harmful emissions from both fermentation tanks and dryers. CO₂ scrubbers control the emissions from the fermentation tanks, while the emissions from the dryers are controller by regenerative thermal oxidizers. These methods are expensive to operate. A potential alternative is bio-trickling filters. Bio-trickling filters are an inexpensive and environmentally friendly alternative. For this study, two parallel bio-trickling filters were operated one at 25°C called the mesophilic bio-trickling filter and one at 60°C called the thermophilic bio-trickling filter. The mesophilic bio-trickling filter simulates emissions from fermentation …

Optimum Mixing Design Of Xanthan And Gellan Treated Soils For Slope Stabilization For Weathered Shales And Glacial Tills In Nebraska, Layal Bitar

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Verdigre located in North Eastern Nebraska experienced slope failures. The geological formations of theses slopes largely consist of several layers of weathered shales and glacial tills. It is believed that the weathering process reduced the shear strength of the soils leading to slope failures.

In this study, strength characteristics of Xanthan and Gellan gums treated soil specimens compacted at the optimum moisture content for field application were investigated so that the biopolymer treated soils may be properly used to stabilize the slopes. The untreated and treated samples were subjected to a wet-freeze(-6^oF)-thaw(167^oF)-dry weathering process up to …

Development Of A Mash Test Level 4 Open Concrete Bridge Rail, Jacob Delone

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

An open concrete bridge rail was designed and developed according to safety performance guidelines in the American Association of State Highway Transportation Officials (AASHTO) Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). Systems designed and developed under previous guidance were studied, and their geometric information and full-scale crash testing performance was studied to establish the geometry of the new bridge rail. Yield-Line Theory and the AASHTO Post and Beam design methods were studied, and a modified version of the AASHTO Post and Beam method was utilized to determine the capacity of the new open concrete bridge rail. …

Development Of An Improved Arterial Roadway Performance Reliability Methodology, Ernest Tufuor

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The need for reliable performance measures of urban arterial roadways is increasing because of the rise in traffic congestion and the high value of travel time. Consequently, travel time reliability (TTR), which combines components of measures of central tendency and measures of dispersion of travel times, has recently received considerable research interest.

The basis of all TTR metrics is the travel time distribution (TTD). Estimating and forecasting arterial TTDs for TTR analysis is the focus of this dissertation. This dissertation proposes a new TTR methodology that is a marked improvement on recent TTR estimation and forecasting methodologies including the current …

Riveted Steel Railway Bridge Health Monitoring And Damage Detection, Ahmed Rageh

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Visual inspection is often used to assess the condition of railway bridges at discrete points in time, an approach that can be subjective and possibly unsafe. Alternatively, certain bridges have their condition assessed via the installation of a large number of sensors. These sensors can be costly to place, power and maintain. Therefore, reducing their numbers and maximizing the extracted information is of utmost importance. In addition, evaluating bridge condition from measured response can be quite challenging due to loading and environmental variations, especially when a limited number of sensors are used.

The focus of this research is to develop …

Nitrate And Herbicides Removal From Groundwater Using Immobilized Algae, Sara Mollamohammada

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

To improve crop yield and control broadleaf weeds, many farmers apply nitrate-based fertilizers and chemical herbicides to their fields. Excessive use of these chemicals can cause contamination in waterbodies and impact on the public health. The physical and chemical methods have been suggested to remove these herbicides are usually costly. In this study, the capability of immobilized algal beads in removing nitrate and several herbicides of environmental concern from synthetic and actual groundwater and surface water was evaluated.

The experiments were performed in batch, sequencing batch and continuous flow modes and the effect of different operational conditions (light intensity, cultivation …

Reliability-Calibrated Ann-Based Load And Resistance Factor Load Rating For Steel Girder Bridges, Francisco Garcia

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

This research aimed to develop a supplemental ANN-based tool to support the Nebraska Department of Transportation (NDOT) in optimizing bridge management investments when choosing between refined modeling, field testing, retrofitting, or bridge replacement. ANNs require an initial investment to collect data and train a network, but offer future benefits of speed and accessibility to engineers utilizing the trained ANN in the future. As the population of rural bridges in the Midwest approaching the end of their design service lives increases, Departments of Transportation are under mounting pressure to balance safety of the traveling public with fiscal constraints. While it is …

Eliminating Rebar Splicing In Transverse Joints Of Precast Full Depth Bridge Deck Panels, David Gee

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

This study looks at the removal of longitudinal rebar splicing when sufficient longitudinal post-tensioning is provided for full-depth precast deck panels for simply supported bridges. Full-depth precast prestressed concrete deck panels are high quality plant produced pretensioned panels. They are often post-tensioned at the site to provide an average net compression in the joint of at least 250 psi due to effective prestress. This is to ensure adequate transfer of load as truck wheels pass over the joint. This net compression on the transverse joint is not explicitly clear by the AASHTO LRFD Bridge Design Specifications. Based on this section, …

Lidar Assessment To Monitor Bridge Response Under Live And Dead Loads, Daniel Watson

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Understanding how a bridge structure responds to various loads in a time and resource-efficient approach is vital in characterizing bridge health. Bridge health monitoring is an evaluation of the structural condition and performance, which optimizes limited transportation budgets by prioritizing the bridges that are in the most need for retrofit or replacement. Identifying and remedying issues will mitigate long-term problems and ensure that the bridge remains open to service for all legal loads. In contrast, health monitoring and load rating will determine if a bridge can only carry traffic up to a certain weight or speed, requiring a bridge load …

Multiscale Modeling Of Fracture In Quasi-Brittle Materials Using Bifurcation Analysis And Element Elimination Method, Keyvan Zare Rami

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Analyzing the fracture of heterogeneous materials is a complex problem, due to the fact that the mechanical behavior of a heterogeneous material is strongly dependent on a variety of factors, such as its microstructure, the properties of each constituent, and interactions between them. Therefore, these factors must be effectively taken into account for accurate analysis, for which the multiscale method has been widely used. In this scheme, the computational homogenization method is used to obtain the effective macroscopic properties of a heterogeneous material based on the response of a Representative Volume Element (RVE). The growth of damage in an RVE …

Development Of A Mix Design Adjustment Method For Fiber Reinforced Concrete And Super High Performance Concrete Based On Excess Paste, Joe Malloy

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

The main objective of this study was to develop a mix design adjustment method for Fiber Reinforced Concrete (FRC) that would maintain appropriate workability while improving hardened concrete performance. A literature review was conducted to examine existing methods for adjusting mix designs to account for fiber introduction. It was found that while increasing fine aggregate and cement paste content can make up for lost workability with the addition of fibers, no rational mix design adjustment method is available. Reference mix designs from the Nevada Department of Transportation and the Nebraska Department of Transportation were used, and this study focused on …

Environmental Sustainability Assessment Of Small Nebraska Mechanical Water Resource Recovery Facilities: Impacts Of Construction And Operations, Sussan Moussavi

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Many small, rural communities struggle with aging or inadequate water resource recovery facilities (WRRFs), and face challenges in constructing and operating such systems. Although existing literature has provided insight into the environmental sustainability of large systems including both the construction and operational phases, these studies have not examined small systems in adequate depth or breadth. The environmental impacts associated with construction may be notable for small WRRFs since the initial construction can be a larger share of the total life cycle environmental impact.

The goal of this work is to provide the environmental sustainability profiles of 12 mechanical WRRFs in …

Evaluation Of Internally Cured Bridge Deck Concrete With Standard And Optimized Aggregate Gradation, Arman Abdigaliyev

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Due to the relatively high cement content and low water-to-cement ratio (w/c) used, bridge deck concrete is prone to premature cracking. Internal curing has been found to greatly reduce the chance of premature cracking as well as concrete deterioration. This research developed internally cured bridge deck concrete based on a local mix design in Nebraska. Four different lightweight fine aggregate (LWFA) as internal curing agents were evaluated and their effects on fresh, mechanical, durability, and shrinkage properties of concrete were studied. The study focused on resolving two issues associated with fine aggregate replacement based on Bentz equation. To identify the …

Effects Of Nutrient Level And Growth Rate On Mutation And Conjugation Processes That Confer Antibiotic Resistance To E. Coli, Mohammadreza Shafieifini

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Antibiotic resistance genes (ARGs) may enter surface water with the discharge of treated wastewater. Conjugation is a main mechanism for the horizontal gene transfer of ARGs from wastewater microbiome to the microbiome indigenous to surface water. However, little is known about how environmental factors affect the conjugation process of ARGs.

In this thesis, an extensive research related to spreading antibiotic resistance genes in the environment is reported. The project investigated how environmental parameters may affect the rate of dissemination of ARGs and in what extent the resistance level of the population is changed after mutation and conjugation event. The chemostat …

Probabilistic Analysis Of Slide-Rocking Structures Under Earthquake Loads, Taylor J. Knickerbocker

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Estimates of rare seismic hazard are essential for the resilience of critical infrastructure and facilities. However, these estimates are highly uncertain at long return periods due to the lack of observed earthquake records. Several ground motion prediction equations have been proposed to close this gap and estimate rare seismic demands; however, these models were developed based on more moderate earthquake records and can yield physically unrealizable ground motions when extrapolated to long return periods. For this reason, seismologists have proposed using precariously balanced rocks (PBRs) as a way to constrain rare seismic hazard. PBRs are a type of fragile geologic …

Numerical Simulation Of Diffuse Ultrasonic Waves In Concrete, Hossein Ariannejad

Department of Civil and Environmental Engineering: Dissertations, Theses, and Student Research

Concrete can be subject to various type of damages. Some damages such as Alkali Silica Reaction (ASR) tend to start from the inside, where there is no easy way to identify or evaluate them in the early stage. The study of ultrasonic waves scatterings in non destructive testing (NDT) methods play a major role in identifying such damages. In an ultrasonic test, high frequency ultrasonic waves are used to interrogate the internal structure of concrete material, where the coarse aggregates and microcracks cause multiple scattering of ultrasonic waves. Experimental studies have demonstrated that diffuse ultrasonic waves scattered by boundaries, coarse …