Civil and Environmental Engineering Commons^™

Development Of System Reliability Models For Railway Bridges, Anna Maria Rakoczy

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

Performance of the railway transportation network depends on the reliability of railway bridges, which can be affected by various forms of deterioration and extreme environmental conditions. More than half of the railway bridges in US were built before 1950 and many show signs of distress. There is a need for efficient methods to evaluate the safety reserve in the railway bridges by identification of the most sensitive parts of the bridge.

An accurate estimation of remaining fatigue life of a structural component is very important in prioritizing bridge rehabilitation and replacement. However, existing procedures to evaluate the fatigue behavior of …

Development And Recommendation For A Non-Proprietary, High-Tension, Cable End Terminal System, Ryan J. Terpsma, Ronald K. Faller, Dean L. Sicking, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Test Matrices For Evaluating Cable Median Barriers Placed In V-Ditches, Ronald K. Faller, Scott K. Rosenbaugh, Mario Mongiardini, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Research On Roadway Performance And Distress At Low Temperature, Yong-Rak Kim, Soohyok Im, Hoki Ban

Nebraska Department of Transportation: Research Reports

This research project investigated the performance and damage characteristics of Nebraska roadways at low-temperature conditions. To meet the research objective, laboratory tests were incorporated with mechanistic numerical modeling. The three most common pavement structures in Nebraska were selected and modeled considering local environmental conditions and pavement materials with and without truck loading. Cracking of asphalt overlay was predicted and analyzed by conducting finite element simulations incorporated with cohesive zone fracture. Parametric analyses were also conducted by varying pavement geometries and material properties, which could lead to helping pavement designers understand the mechanical sensitivity of design variables on the overall responses …

Safety Improvements At Highway-Railroad Crossing For Pedestrians And Bicyclists And The Assessment Of Long-Term Effects Of Centerline Curbing, Aemal Khattak, Zheng Luo

Nebraska Department of Transportation: Research Reports

No abstract provided.

Co-Removal Of Atrazine And Nitrate From Groundwater Using A Mulch Biofilm, Allison L. Cole

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

The popular broadleaf herbicide atrazine is often found in contaminated groundwater along with other agricultural chemicals, such as nitrate. Mulch biowalls, a passive treatment placed in situ, can inexpensively remediate groundwater by intercepting and treating a contaminant plume. Three types of organic mulch: cedar, cypress, and hardwood were evaluated for their ability to act as supporting materials for a biowall to simultaneously remove atrazine and nitrate from groundwater. Physical and chemical properties of the mulch were characterized. Cedar mulch had the highest organic carbon content, 996 mg/g. The adsorptive capacity of the mulch for atrazine and nitrate, in mono …

Prestressed Concrete Wind Turbine Supporting System, Ibrahim Lotfy

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

Wind energy is one of the most commercially developed and quickly evolving renewable energy technologies worldwide. Wind turbines are commonly supported on tubular steel towers. As the turbines are growing and the towers are elevating, an increase in structural strength and stiffness is required to withstand the applied forces. Recent studies established concrete as a more economic and durable alternative to steel especially when the tower height exceed 240ft. Presently, concrete towers are not common due to their perceived heavy weight and assembly complexity. One of the systems that have been mentioned in the literature consists of precast rings that …

Curriculum Development For Recession Displaced Workers In Green Construction Industries, John Earl Killingsworth

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

More than 8 million U.S. jobs were lost during ‘The Great Recession’, pushing unemployment from 4.4% in 2007 to 10.2% in 2009. Nearly half of all job losses occurred among lower-skilled workers in construction and manufacturing industries. During this same period, however, jobs in energy efficiency and renewable energy industries grew an unprecedented 9%. As part of a $4.8M grant from the U.S. Department of Labor, the University of Nebraska began development of a workforce transition program to ‘retool’ recession displaced workers for career opportunities in new and emerging green industries. To date, the knowledge, skills, and abilities (KSAs) of …

Efficient Precast/Prestressed Floor System For Building Construction, Eliya E. A. Henin

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

Precast floor systems provide a rapidly constructed solution to multi-story buildings that is economical, high quality, fire-resistant, and with excellent deflection and vibration characteristics. Conventional precast concrete floor system cannot compete with cast-in-place post tensioning flat slab floor systems when high span-to-depth ratio and flat soffit are required. This is due to the significant depth of standard precast beams, and use of column corbels and beam ledges. This research presents the development of a new precast concrete floor system that eliminates the limitations of conventional precast floor system and provides a competitive precast alternative to cast-in-place flat slab floor systems. …

Improved Models Of Cable-To-Post Attachments For High-Tension Cable Barriers, Robert W. Bielenberg, Cody S. Stolle, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Improved Models Of Cable-To-Post Attachments For High-Tension Cable Barriers, Robert W. Bielenberg, Cody S. Stolle, John D. Reid

Nebraska Department of Transportation: Research Reports

Computer simulation models were developed to analyze and evaluate a new cable-to-post attachment for high-tension cable barriers. The models replicated the performance of a keyway bolt currently used in the design of a high-tension cable median barrier being developed at the Midwest Roadside Safety Facility. Component tests of the keyway bolts were simulated and compared to the component test results. Accurate friction, fracture strain, and stress-strain material properties were determined for a solid element model of the keyway bolt by applying actual load curve measured from the test to a simulated pull cable. By simulating the material properties of the …

Nutrient Losses In Runoff From Feedlot Surfaces As Affected By Unconsolidated Surface Materials, John E. Gilley, Jason R. Vogel, Roger A. Eigenberg, David B. Marx, Brian L. Woodbury

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Beef cattle feedlots contain unconsolidated surface materials (loose manure pack) that accumulate during a feeding cycle. The effects of varying amounts of unconsolidated surface materials on runoff nutrient losses are not well understood. The objectives of this study were to (1) compare runoff nutrient losses from feedlot surfaces containing varying amounts of unconsolidated surface materials, (2) determine if differences in runoff nutrient losses exist among rainfall simulation runs, (3) relate runoff nutrient losses to selected feedlot soil characteristics, and (4) identify the effects of varying runoff rate on nutrient loss rates from feedlot surfaces. This study was conducted on 0.75 …

Transversely Post-Tensioned Box-Beam System For Precast Parking Structures, Jenna Hansen

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

Parking structures are essential to any growing commercial district, yet little thought is given to their longevity and appearance. This is particularly the case with precast parking structures. Typical issues include poor joint performance and the impact of stemmed members on interior building aesthetics. Research provided in this report proposes an alternate design that improves long term joint performance and optimizes the perspective spacing between deck members. These benefits (along with the others) are incorporated to reflect the benefits of parking structures designed using cast-in-place concrete and structural steel with concrete decking. Other benefits include: flexible column spacing, reduced / …

Safety Investigation And Guidance For Retrofitting Existing Approach Guardrail Transitions, Eric R. Jowza

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

Throughout the United States, various approach guardrail transition systems are routinely implemented by State Highway Departments to connect standard strong-post, W-beam guardrail systems to the blunt end of concrete bridge rails and roadside median barriers. When installed correctly, approach guardrail transitions shield the hazardous exposed ends of rigid parapets as well as significantly reduce the propensity for wheel snag and vehicle pocketing throughout the transition region. Unfortunately, approach guardrail transitions that are installed in the field may not always resemble that of the as-tested configuration, thus reducing the desired lateral stiffness and strength of the transition system. A recent survey …

An Evaluation Of Non-Intrusive Traffic Detectors At The Ntc/Ndor Detector Test Bed, Benjamin W. Grone

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

Throughout the field of transportation engineering, decision makers require quality information. The information used in transportation operations, planning, and design is based, in part, on data from traffic detectors. The need for quality data has spurred innovations in data collection including the introduction of modern, commercially available, non-intrusive traffic detectors. As these new technologies become available, a need exists to understand their capabilities and limitations—especially limitations that are unique to a specific region.

This thesis examined the accuracy of four non-intrusive traffic detector technologies considered for potential data collection applications on Nebraska’s highways. The technologies evaluated included the Solo Pro …

Characterization Of Viscoelastic And Fracture Properties Of Asphaltic Materials In Multiple Length Scales, Soohyok Im

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

Asphaltic materials are classical examples of multi-phase composites in different length scales. The understanding of the mechanical behavior of asphaltic materials has been a challenge to the pavement mechanics community due to multiple complexities involved: heterogeneity, anisotropy, nonlinear inelasticity, and damage in multiple forms. The micromechanics-based models based on numerical methods have been receiving attention from the pavement mechanics community because the modeling method can account for those complexities of asphaltic materials by considering the effects of material properties and geometric characteristics of individual components on overall performance behavior of mixture or structure. As a step-wise effort, this study intends …

Effects Of Manure Handling And Application Method On Odor And Gas Emission Potential Of Swine Manure, Rick R. Stowell

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Manure composition and emissions potential of swine manure were investigated in opposing contexts of desired and undesired methane generation. In the main study, the full-scale treatment effects of anaerobic digestion on the air emissions potential of swine manure were investigated. Manure slurry and digester effluent samples were collected from a pork production facility in eastern Nebraska that utilizes a complete-mix anaerobic digester to treat the manure and produce biogas for use in generating electricity. Samples were collected from three sites in the manure stream (below-barn pit, digester outlet, and holding pond) from 9/22/08 through 12/2/09 in order to observe changes …

Assessing Impermeable Surface Area Impacts On Modeling: Implications For The Combined Sewer Overflow Long Term Control Plan In Omaha, Nebraska, Andrew D. Szatko

Community and Regional Planning Program: Professional Projects

The report looks at assessing the accuracy of estimating impervious surface areas (ISAs) by zoning code, the method utilized by the City of Omaha, Nebraska. A 101 acre subcatchment had all ISAs manually digitized and compared the actual with the estimated value. The subcatchment was then modeled with 10 percent decreases of ISAs to establish the relationship with peak flow rates and total volume in the combined sewer service area. The results show a significant relationship between the two that may provide insights into a new approach to manage CSO events with the integration of green infrastructure.

Speed Limit Recommendation In Vicinity Of Signalized High-Speed Intersection, Anuj Sharma, Laurence Rilett, Zifeng Wu, Shefang Wang

Nebraska Department of Transportation: Research Reports

No abstract provided.

Soil Greenhouse Gas Emissions In The Life Cycle Assessment Of Cellulosic Ethanol From Crop Residue, Xiao Xue Fang

Department of Agricultural and Biological Systems Engineering: Dissertations, Theses, and Student Research

Concerns about climate change and the increasing cost of fossil fuels have led to interest in the development of renewable biofuel pathways for reducing greenhouse gas (GHG) emissions. The use of corn residue as a potential source of biomass feedstock for cellulosic ethanol production has been favored as cost effective. Previous research has shown that crop residue removal can cause a loss of soil organic carbon (SOC), which potentially is a source of GHG emissions in the form of CO₂. Using a life cycle assessment (LCA) approach, this study investigated the impact of corn residue removal on total …

Evaluation Of The Bank Stability And Toe Erosion Model (Bstem) For Predicting Lateral Retreat On Composite Streambanks, Taber L. Midgley, Garey A. Fox, Derek M. Heeren

Department of Agricultural and Biological Systems Engineering: Faculty Publications

Streambank erosion is known to be a major source of sediment in streams and rivers. The Bank Stability and Toe Erosion Model (BSTEM) was developed in order to predict streambank retreat due to both fluvial erosion and geotechnical failure. However, few, if any, model evaluations using long-term streambank retreat data have been performed. The objectives of this research were to (1) monitor long-term composite streambank retreat during a hydraulically active period on a rapidly migrating stream, (2) evaluate BSTEM’s ability to predict the measured streambank retreat, and (3) assess the importance of accurate geotechnical, fluvial erosion, and near-bank pore-water pressure …

Impact Of Signal Timing Information On Safety And Efficiency Of Signalized Intersections, Anuj Sharma, Lelitha Vanajakshi, V. Girish, M. S. Harshitha

Department of Civil and Environmental Engineering: Faculty Publications

Signalized intersections are provided in traffic networks to improve the safety and efficiency of vehicular and pedestrian movement. There are various measures under education, enforcement and engineering headings that are being attempted to improve safety and efficiency of operations at a signalized intersection. Provision of signal countdown timer, a timer showing the remaining red and green time in a phase, is one such measure and is commonly adopted in India. However, studies on effects of countdown timer under Indian traffic conditions are very scarce. Traffic heterogeneity and lack of lane discipline makes transferability of models developed in other countries (with …

Development Of Best Management Practice Design Guidance For Roadway Applications In Nebraska, Benedict Vacha

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

Runoff from roadways carries pollutants which may be detrimental to aquatic ecosystems. The primary pollutants of concern for roadway runoff are solids and heavy metals, particularly cadmium, copper, and zinc. Roadway runoff falls under the legislation of the Clean Water Act (CWA) via the National Pollutant Discharge Elimination System (NPDES). CWA regulates discharge of nonpoint source pollutants, such as roadway runoff, by issuing permits to public entities which manage Municipal Separate Storm Sewer Systems (MS4s). Part of the Nebraska Department of Roads (NDOR) permitting requirement is to create a design guide for Best Management Practices (BMPs) tailored to remediate roadway …

Development And Recommendations For A Non-Proprietary, High-Tension, Cable End Terminal System, Ryan J. Terpsma

Department of Mechanical and Materials Engineering: Dissertations, Theses, and Student Research

Cable guardrail systems have been increasing in popularity in recent years due to several perceived benefits over the commonly used W-beam guardrail. A non-proprietary design was desired as an alternative to the many proprietary designs available. A non-proprietary, high-tension cable end terminal was necessary to accompany the non-proprietary, high-tension cable guardrail system under development.

The objective of this research project was to develop design recommendations for a non-proprietary, high-tension cable end terminal. An analysis of several cable guardrail end terminals was undertaken to identify any common features that may prove to be beneficial or detrimental to end terminal designs. Next, …

Phase Ii Development Of A Non-Proprietary, Four-Cable, High Tension Median Barrier, Jennifer D. Schmidt, Dean L. Sicking, Ronald K. Faller, Karla A. Lechtenberg, Robert W. Bielenberg, Scott K. Rosenbaugh, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

Determination Of The Maximum Mgs Mounting Height -- Phase I Crash Testing, Cale J. Stolle, Karla A. Lechtenberg, Ronald K. Faller, Robert W. Bielenberg, Scott Rosenbaugh, Dean L. Sicking, John D. Reid, Erin A. Johnson

Nebraska Department of Transportation: Research Reports

No abstract provided.

Global Monthly Water Scarcity: Blue Water Footprints Versus Blue Water Availability, Arjen Y. Hoekstra, Mesfin Mekonnen, Ashok K. Chapagain, Ruth E. Mathews, Brian D. Richter

Daugherty Water for Food Global Institute: Faculty Publications

Freshwater scarcity is a growing concern, placing considerable importance on the accuracy of indicators used to characterize and map water scarcity worldwide. We improve upon past efforts by using estimates of blue water footprints (consumptive use of ground- and surface water flows) rather than water withdrawals, accounting for the flows needed to sustain critical ecological functions and by considering monthly rather than annual values. We analyzed 405 river basins for the period 1996–2005. In 201 basins with 2.67 billion inhabitants there was severe water scarcity during at least one month of the year. The ecological and economic consequences of increasing …

The Water Footprint Of Humanity, Arjen Y. Hoekstra, Mesfin Mekonnen

Daugherty Water for Food Global Institute: Faculty Publications

This study quantifies and maps the water footprint (WF) of humanity at a high spatial resolution. It reports on consumptive use of rainwater (green WF) and ground and surface water (blue WF) and volumes of water polluted (gray WF). Water footprints are estimated per nation from both a production and consumption perspective. International virtual water flows are estimated based on trade in agricultural and industrial commodities. The global annual average WF in the period 1996–2005 was 9,087 Gm3 ∕y (74% green, 11% blue, 15% gray). Agricultural production contributes 92%. About one-fifth of the global WF relates to production for export. …

Phase I Development Of An Aesthetic, Precast Concrete Bridge Rail, Scott Rosenbaugh, Ronald K. Faller, Robert W. Bielenberg, Dean L. Sicking, John D. Reid

Nebraska Department of Transportation: Research Reports

No abstract provided.

A Global Assessment Of The Water Footprint Of Farm Animal Products, Mesfin Mekonnen, Arjen Y. Hoekstra

Daugherty Water for Food Global Institute: Faculty Publications

The increase in the consumption of animal products is likely to put further pressure on the world’s freshwater resources. This paper provides a comprehensive account of the water footprint of animal products, considering different production systems and feed composition per animal type and country. Nearly one-third of the total water footprint of agriculture in the world is related to the production of animal products. The water footprint of any animal product is larger than the water footprint of crop products with equivalent nutritional value. The average water footprint per calorie for beef is 20 times larger than for cereals and …