Civil Engineering Commons^™

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 …

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 …

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, …

Optfill: A Tool For Infeasible Cycle-Free Gapfilling Of Stoichiometric Metabolic Models, Wheaton L. Schroeder, Rajib Saha

Mid-America Transportation Center: Final Reports and Technical Briefs

Stoichiometric metabolic modeling, particularly genome-scale models (GSMs), is now an indispens- able tool for systems biology. The model reconstruction process typically involves collecting informa- tion from public databases; however, incomplete systems knowledge leaves gaps in any reconstruc- tion. Current tools for addressing gaps use databases of biochemical functionalities to address gaps on a per-metabolite basis and can provide multiple solutions but cannot avoid thermodynami- cally infeasible cycles (TICs), invariably requiring lengthy manual curation. To address these limita- tions, this work introduces an optimization-based multi-step method named OptFill, which performs TIC-avoiding whole-model gapfilling. We applied OptFill to three fictional prokaryotic models …

Calibrating The Highway Capacity Manual Arterial Travel Time Reliability Model, Ernest Tufuor, Laurence Rilett, Li Zhao

Mid-America Transportation Center: Final Reports and Technical Briefs

The latest edition of the Highway Capacity Manual (HCM-6) includes, for the first time, a methodology for estimating and predicting the average travel time distribution (TTD) of urban streets. Travel time reliability (TTR) metrics can then be estimated from the TTD. The HCM-6 explicitly considers five key sources of travel time variability. A literature search showed no evidence that the HCM-6 TTR model has ever been calibrated with empirical travel time data. More importantly, previous research showed that the HCM-6 underestimated the empirical TTD variability by 70% on a testbed in Lincoln, Nebraska. In other words, the HCM-6 TTR metrics …

Analysis Of Component Errors In The Highway Capacity Manual Travel Time Reliability Estimations For Urban Streets, Ernest Tufuor, Laurence Rilett

Mid-America Transportation Center: Final Reports and Technical Briefs

The Highway Capacity Manual 6th edition (HCM6) includes a new methodology to estimate and predict the distribution of average travel times (TTD) for urban streets. The TTD can then be used to estimate travel time reliability (TTR) metrics. Previous research on a 0.5-mi testbed showed statistically significant differences between the HCM6 estimated TTD and the corresponding empirical TTD. The difference in average travel time was 4 s that, while statistically significant, is not important from a practical perspective. More importantly, the TTD variance was underestimated by 70%. In other words, the HCM6 results reflected a more reliable testbed than field …

An Integrated Computational And Experimental Study To Investigate Staphylococcus Aureus Metabolism, Mohammad Mazharul Islam, Vinai C. Thomas, Matthew Van Beek, Jong-Sam Ahn, Abdulelah A. Alqarzaee, Chunyi Zhou, Paul D. Fey, Kenneth W. Bayles, Rajib Saha

Mid-America Transportation Center: Final Reports and Technical Briefs

Staphylococcus aureus is a metabolically versatile pathogen that colonizes nearly all organs of the human body. A detailed and comprehensive knowledge of staphylococcal metabolism is essential to understand its pathogenesis. To this end, we have reconstructed and experimentally validated an updated and enhanced genome-scale metabolic model of S. aureus USA300_FPR3757. The model combined genome annotation data, reaction stoichiometry, and regulation information from biochemical databases and previous strain-specific models. Reactions in the model were checked and fixed to ensure chemical balance and thermodynamic consistency. To further refine the model, growth assessment of 1920 nonessential mutants from the Nebraska Transposon Mutant Library …

Corrigendum To “Heavy Metal Ion Detection On A Microspot Electrode Using An Optical Electrochemical Probe” [Electrochem. Commun. 86 (2018) 94–98], Santanu Roy, Abhijeet Prasad, Rahul Tevatia, Ravi Saraf

Mid-America Transportation Center: Final Reports and Technical Briefs

The authors regret to inform an error. Ravi F. Saraf of this pub- lication discloses financial interest in Vajra Instrument as its founder and President. In accordance with its Conflict of Interest policy, the University of Nebraska-Lincoln’s Conflict of Interest in Research Committee has determined that this must be disclosed. The authors would like to apologise for any inconvenience caused.

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 …

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 …

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 …

Full Scale 13-Story Building Implosion And Collapse: Effects On Adjacent Structures, Kanchan Devkota

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

Two dormitory halls at the University of Nebraska-Lincoln known as Cather and Pound halls were demolished via controlled implosion on December 22, 2017. Cather and Pound halls were two thirteen-story reinforced concrete structures. The demolition of these two structures included the implosion of controlled charges at selected columns on alternating floors which initiated the progressive collapse of these structures. Three nearby structures in the vicinity of Cather and Pound halls were instrumented with high sensitivity uniaxial piezoelectric accelerometers to record the response of the adjacent structures during the event of the implosion and the progressive collapse. While these two thirteen-story …

Application Of Remote Sensing Technology In Water Resources Management, Mahesh Pun

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

The primary goal of this dissertation was to leverage the capabilities of remote sensing technology for capturing detailed spatial information at different spatial resolutions to monitor agricultural crops and generate accurate input datasets for water resources models. This dissertation is divided into three different research studies. In the first study, a remote sensing classification method was developed for classifying irrigated and non-irrigated fields that integrates Vegetation indices with surface energy balance fluxes. The method was applied in the COHYST2010 hydrological model region with wide climate variation and to multiple growing seasons with results that were 92.1% accurate and explained 97% …

Boy Scouts Of America Concept Site Master Plan And Improvements, Anna Cole, Jacob Chekal, William Seeger, Shanon Al-Brady, Nicholas Cowles

Honors Program: Senior Projects (Public)

Our team, G1 Engineering, has partnered with the Boy Scouts of America to provide an update to their master plan for the Outdoor Education Center site located at 600 S. 120^th Street, Lincoln, NE. Our work included providing transportation solutions; drainage evaluations; investigation of geotechnical conditions; environmental evaluation and determination of permitting requirements; preparation of concept design plans for bridges, drainage, utilities, and overall site plan; and evaluation of structural elements included in the project.

Two streams cross the property presenting site access issues. Our team provided pedestrian, UTV, and emergency vehicle access bridges to address these issues. With …

Outdoor Education Center Concept Site Master Plan And Improvements As Designed By Wingineers, Christina Thibodeau

Honors Program: Senior Projects (Public)

This thesis builds on a basis of four years of engineering education to produce a final project for the capstone course. The idea behind this project was to provide a workable master plan and conceptual site improvements for a real application, the Outdoor Education Center in east Lincoln, Nebraska. The Boy Scouts of America Cornhusker Council and the University of Nebraska – Lincoln Department of Civil Engineering have cooperated throughout the Senior Design capstone course to make this possible for the students involved.

Restricted Crossing U-Turns At Rural Intersections, Timothy Adams

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

This study examines the potential for replacing the standard intersection design at two-way stop control (TWSC) and all-way stop control (AWSC) intersections along rural highways with a roundabout or a restricted crossing u-turn (RCUT) facility. The geometry of the RCUT design prohibits left and through movements from the side road, and provides a u-turn location downstream from the main crossing. This type of facility has been implemented for rural highways extensively in other states and has the potential to serve as a cost-effective solution to improve roadway safety within Nebraska.

Comparative analysis is conducted for three site locations (Humphrey, Madison, …

Biofiltration Of Volatile Organic Compounds Emitted At Ethanol Plants, Christopher Arthur Duerschner

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

Ethanol manufacturing is an important and growing sector in the biofuels marketplace. At ethanol plants, the control of volatile organic compound containing emissions from fermentation tanks and distillers dried grains with solubles driers is accomplished through the use of air scrubbers and regenerative thermal oxidizers. The operation of these control units imposes substantial operating costs for the ethanol plant. Biotrickling filters have the ability to replace scrubbers and regenerative thermal oxidizers resulting in significant economic and environmental benefits. Two biotrickling filters were operated in parallel under acetaldehyde loadings ranging from 4 to 136 gm^-3hr^-1. To examine …

Unl-Cc Outdoor Education Center Master Plan, Marie Wagner

Honors Program: Senior Projects (Public)

The following report contains the work done by the group Griswold Engineering in completion of the Senior Design requirements for Civil Engineering and the Honors Requirements of the Project Manager. As the project manager, my job was to organize the project as a whole and to work alongside the Structural Engineer on the project. One of the main problems to overcome was the division of labor amongst the group. The project was originally conceived as a group project with one project manager and five other students to serve as the project engineers in each subdiscipline. Since this group only had …

Development Of Post-To-Deck Connections For Use In A Mash Tl-4 Steel-Tube Bridge Rail, Pascual Mauricio

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

A new post-to-deck connection was designed for mounting an upcoming Manual for Assessing Safety Hardware (MASH) Test Level 4 steel-tube bridge rail to the side of the bridge deck to limit impact load transferred to the deck and to minimize the propensity for deck damage during impacts. With preference for the bridge rail system to be compatible for use on all deck configurations, the Illinois and Ohio Departments of Transportation desired the new system to attach to bridge decks comprised of concrete slabs or precasted prestressed, concrete box-beam girders.

A new post-to-deck connection for a new MASH 2016 TL-4 steel-tube …

Development Of A Mash Tl-4 Steel, Side-Mounted, Beam-And-Post, Bridge Rail, Oscar Pena

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

A new steel, side-mounted, beam-and-post, bridge rail was designed, crash-tested, and evaluated according to safety performance guidelines included in the American Association of State Highway and Transportation Officials Manual for Assessing Safety Hardware (MASH) for Test Level 4 (TL-4). The new bridge rail system was designed to be compatible to multiple concrete bridge decks utilized by the States of Illinois and Ohio. Bridge rail configurations were designed and optimized based on weight per foot, constructability, and safety. Post-to-rail and rail-to-rail connections were designed for the new bridge rail. Several concepts for these connections were configured, and after discussion with representatives …

Simulation Of Antimicrobial Resistance Gene Fate In Narrow Grass Hedges, Marzieh Khedmati

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

Vegetative Filter Strips (VFS) are used for controlling the volume of runoff and decreasing the contaminants in runoff before entering the water bodies. Many studies investigated the role of VFS in sediment and nutrient removal, but little is known about their efficiency in the removal of emerging contaminants such as antimicrobial resistance genes (ARGs). VFSMOD was used to simulate the efficiency of VFS in this regard. The objectives of this study were to calibrate the VFSMOD with some experimental data and asses the efficiency of the model in simulating the filter behavior in removing ARGs. The tests were conducted in …

Civil Engineering Design Of Cornhusker Council's Outdoor Education Center, Kelly Weiler

Honors Program: Senior Projects (Public)

A team of geotechnical, structural, hydraulic, environmental, and transportation experts collaborated to provide engineering solutions to the Cornhusker Council in an effort to solve the current problems facing their Outdoor Education Center. This results of this project provided the structural design of three bridges on the property, transportation plans for two parking lots and roadway design, geotechnical recommendations for soil testing and erosion prevention, and an environmental and hydraulic analysis of the property. A major challenge in the design of this project is the consideration of the dangers and regulations that accompany the floodway and floodplain regions on site. Various …

Using Theoretical And Experimental Particle Packing For Aggregate Gradation Optimization To Reduce Cement Content In Pavement Concrete Mixtures, Miras Mamirov

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

The main objective of this study was to evaluate the effect of aggregate particle packing optimization and cement reduction on Nebraska slip-form pavement concrete performance. A literature review was conducted to examine different aggregate optimization tools, quality control tests, and historical data of Nebraska Department of Transportation (NDOT) mixtures. It was found that the Modified Toufar Model has good potential in optimizing particle packing and predicting packing degrees. The combined void content test was found to be useful to experimentally justify optimized aggregate gradations. Two specific pavement concrete workability tests, i.e., the Box Test and the VKelly Test, were used …

Proportion And Evaluation Of Ultra-High Performance Concrete Using Local Materials, Flavia Ribeiro Furtado De Mendonca

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

Ultra-high performance concrete (UHPC) is a new class of concrete that has superior workability, as well as mechanical and durability properties that far exceed those of conventional concrete. To achieve these properties, a very dense internal structure and the very low water-to-binder ratio (w/b) generally are necessary. While particle packing models are typically used to design UHPC, due to the complexity of the composition interaction and characteristics of UHPC, these models might not necessarily provide the best design, which leads to the need of experimental study to justify UHPC performance. The evaluation of the impact of various design parameters on …