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Articles 1 - 30 of 161
Full-Text Articles in Engineering
Predicted Redidual Strength Of Damaged Isotrussâ® Structures, Travis S. Carroll
Predicted Redidual Strength Of Damaged Isotrussâ® Structures, Travis S. Carroll
Theses and Dissertations
This thesis utilized a linear analytical approach to explore the damage tolerance or residual strength as a function of increasing damage in traditional single and hybrid-grid IsoTruss® structures. Residual strength was studied for structures subjected to axial compression, torsion and flexural bending, independently. Carbon/epoxy material properties were applied in all load cases, and fiberglass/epoxy material properties were also applied in the flexural bending case. Prior to imposing damage conditions, the IsoTruss® structures were parametrically optimized to achieve the highest strength-to-weight ratios. Typical compression strut, driveshaft, and utility pole specifications governed the design strength dimensions and boundary conditions. Damage growth was …
Statnamic Lateral Load Testing And Analysis Of A Drilled Shaft In Liquefied Sand, Seth I. Bowles
Statnamic Lateral Load Testing And Analysis Of A Drilled Shaft In Liquefied Sand, Seth I. Bowles
Theses and Dissertations
Three progressively larger statnamic lateral load tests were performed on a 2.59 m diameter drilled shaft foundation after the surrounding soil was liquefied using down-hole explosive charges. An attempt to develop p-y curves from strain data along the pile was made. Due to low quality and lack of strain data, p-y curves along the test shaft could not be reliably determined. Therefore, the statnamic load tests were analyzed using a ten degree-of-freedom model of the pile-soil system to determine the equivalent static load-deflection curve for each test. The equivalent static load-deflection curves had shapes very similar to that obtained from …
A Proposed Framework For Simultaneous Optimization Of Evacuation Traffic Distribution And Assignment, Fang Yuan
A Proposed Framework For Simultaneous Optimization Of Evacuation Traffic Distribution And Assignment, Fang Yuan
Doctoral Dissertations
In the conventional evacuation planning process, evacuees are assigned to fixed destinations based mainly on the criterion of geographical proximity. However, such pre-specified destinations (OD table) almost always lead to sub-optimal evacuation efficiencies due to uncertain road conditions such as congestion, road blockage, and other hazards associated with the emergency. By relaxing the constraint of assigning evacuees to pre-specified destinations, a one-destination evacuation (ODE) concept has the potential of greatly improving the evacuation efficiency. A framework for simultaneous optimization of evacuation traffic distribution and assignment is therefore proposed in this study. Based on the concept of ODE, the optimal destination …
Evaluation Of Heavy-Duty Diesel Vehicle Emissions During Cold-Start And Steady-State Idling Conditions And Reduction Of Emissions From A Truck-Stop Electrification Program, James A. Calcagno
Evaluation Of Heavy-Duty Diesel Vehicle Emissions During Cold-Start And Steady-State Idling Conditions And Reduction Of Emissions From A Truck-Stop Electrification Program, James A. Calcagno
Doctoral Dissertations
Cold-start and extended-idling emissions of carbon monoxide (CO), oxides of nitrogen (NOx) and particulate matter (PM) were measured from 24, class-8B, heavy-duty diesel vehicles (HDDV8B) using portable emission monitoring equipment. The ratio of nitrogen dioxide (NO2) to NOx and the ratio of PM2.5 to total PM were reported. Truck model years ranged from 1992 to 2004. All vehicles were tested in the field during summer and fall months under ambient environmental conditions at low (600-800 rpm) and high (1000 rpm) engine idling speeds with the truck cab air-conditioner operating at “on” and “off” modes. Sampling data thus …
Health Risk Assessment Posed By The Mobile Source Air Toxics On An Urban To Regional Area, Luis Alonso Díaz Robles
Health Risk Assessment Posed By The Mobile Source Air Toxics On An Urban To Regional Area, Luis Alonso Díaz Robles
Doctoral Dissertations
Air toxics are important health concern. The purpose of this research was to develop a protocol to predict exposure concentrations of air toxics and inhalation cancer and noncancer risk that come from different gasoline and diesel-fueled sources. The protocol was developed by linking the U.S. EPA’s Models-3/CMAQ model as the exposure model and toxicological and epidemiological evidence functions. The NEI version 3 for the year 1999 was used in this analysis for point, area, and non-road sources, whereas NMIM was used to create the on-road emissions. The year 2003 was used for meteorological data and as reference to compare the …
The Rrnat/Rdna Ratio As A Measure Of Nitrite Oxidizing Activity, Shawn A. Hawkins
The Rrnat/Rdna Ratio As A Measure Of Nitrite Oxidizing Activity, Shawn A. Hawkins
Doctoral Dissertations
A bench scale nitrification reactor (BSNR) containing nitrite oxidizing bacteria (NOB) of the genus Nitrobacter (» 1 × 1010/L; 5 - 22% of bacteria) was used to assess the ribosomal RNA transcript (rRNAt) to ribosomal RNA gene (rDNA) ratio as an in-situ nitrite oxidizing activity metric. A quantitative PCR detection system was developed that amplified a 143 base pair sequence within the Nitrobacter spp. 16S - 23S intergenenic spacer region. The resulting real-time PCR (rDNA) and real-time RT-PCR (rRNAt) assays were specific, accurate, and sensitive, requiring three replicate nucleic acid extracts to reliably detect a true 2-fold concentration …
Characterizing Turbulence Structure Along Woody Vegetated Banks In Incised Channels: Implications For Stream Restoration, Frank James Dworak
Characterizing Turbulence Structure Along Woody Vegetated Banks In Incised Channels: Implications For Stream Restoration, Frank James Dworak
Masters Theses
The impacts of urbanization have modified natural watersheds and stream hydraulic, hydrologic, and geomorphic processes that have lead to geomorphic and ecological disturbances in natural stream systems. These alterations have resulted in channel incision and the loss of channel-scale hydraulic characteristics responsible for initiating and maintaining pool-riffle bedforms, which are capable of supporting diverse biological stream ecosystems. Through the use of FLOW-3D, a 3-dimensional computational fluid dynamics model, three scenarios of an urban, incised, and channelized stream were simulated to characterize the turbulent, hydraulic structure during bankfull discharge. The simulations were conducted with trees inhibiting bankfull flow (representing the channel’s …
Linking Channel Stability And Bed Sediment Characteristics To Biological Integrity In Tennessee Ridge And Valley Streams, Kelley H. Williams
Linking Channel Stability And Bed Sediment Characteristics To Biological Integrity In Tennessee Ridge And Valley Streams, Kelley H. Williams
Masters Theses
Streambed sedimentation has plagued waterways since the beginning of civilization, whether as a natural flow process or human disturbances on the landscape in more recent times. Due to the continual degradation in the quantity and diversity of aquatic organisms within streams, the issue has finally surfaced as a significant concern. The need to develop better Total Maximum Daily Load (TMDL) assessment tools to link sediment impairment to biological integrity was the driving force behind this study.
Within the Ridge and Valley Ecoregion, 76 stream reaches were analyzed to investigate the impacts of stability issues and bed sediment characteristics on stream …
Evaluation Of Mechanical Properties Of Recycled Aggregate Concrete, Sajjad Ali Khan
Evaluation Of Mechanical Properties Of Recycled Aggregate Concrete, Sajjad Ali Khan
Masters Theses
The maintenance and repair work in the civil engineering infrastructures develops the production of huge wastes which causes the growth of waste piles, additional costs in construction projects and some environmental problems. If this waste is recycled and used again in construction projects, it will help to overcome the problems discussed earlier. Moreover, if natural aggregates are supplemented by recycled aggregate, it will preserve the natural resources and also put a pause in the deterioration of natural landscape.
This thesis addresses the importance of using recycled aggregate in concrete structures. Its practical feasibility in construction projects is studied in light …
Evaluation Of Mechanical Properties Of Self-Consolidating Concrete, Bhusan Basnet
Evaluation Of Mechanical Properties Of Self-Consolidating Concrete, Bhusan Basnet
Masters Theses
The concept of Self-Consolidating Concrete is a fresh and rapidly ramping technology in USA, but in some other continents such as Japan and Europe it is in fully fledged stage. The development of this technology has a high potential to economize construction minimizing labor, scheduled time and equipment eliminating consolidation process. In USA, construction professionals are reluctant to its in-effect application because of lack of deliberate and methodological steps for production and applications. The lack of study of its durability characteristics and confusion in design and production process are seems to be vital factors hindering full scale production and application …
Resilient And Residual Properties Of Asphalt Concrete: Superpave And Conventional Mix Design, Tamer Mohamed Breakah
Resilient And Residual Properties Of Asphalt Concrete: Superpave And Conventional Mix Design, Tamer Mohamed Breakah
Archived Theses and Dissertations
No abstract provided.
An Investigation Of Employee Satisfaction And Employee Empowerment Specific To On-Site Supervisors In The Residential Construction Industry, David Lars Halvorsen
An Investigation Of Employee Satisfaction And Employee Empowerment Specific To On-Site Supervisors In The Residential Construction Industry, David Lars Halvorsen
Theses and Dissertations
Employee satisfaction and empowerment are vital elements to businesses in most industries. The construction industry has various types of employees, ranging from managers and executives to on-site supervisors and laborers. This study was conducted to obtain a greater understanding about the elements and levels of satisfaction and empowerment of on-site supervisors in the residential construction industry. An on-site supervisor in the residential construction industry is responsible for coordinating and managing employees, materials, equipment, budgets, schedules, contracts, and the safety of employees and the general public. They are also the employees most frequently perceived as accountable for the success or failure …
Interior Node Projection Techniques In Sweeping Algorithms, Michael Andrew Scott
Interior Node Projection Techniques In Sweeping Algorithms, Michael Andrew Scott
Theses and Dissertations
The enhancement of node projection techniques in sweeping is the subject of this thesis. Sweeping is a method used to produce all-hexahedral finite element meshes on certain classes of geometry. The placement of nodes in the interior of the geometry during the sweeping process remains a difficult problem. This thesis presents advancements in this area which improve the speed of the algorithm and the resulting element quality. A comparison of existing projection methods was performed. The existing Faceted projection sweeping method was extended to be applicable to more general classes of sweepable geometry. This comparison and extension of node projection …
A Gasless Method Of Spraying Thermoplastic Resin, Dan T. Rogers
A Gasless Method Of Spraying Thermoplastic Resin, Dan T. Rogers
Theses and Dissertations
This spraying method for thermoplastic resins is a new manufacturing process for applying thermoplastics to a mold or surface in an efficient way that has the potential of reducing cycle time. Spraying thermoplastic resins is similar to spraying other polymers, such as paint, with the differences being higher pressure and temperature. This method uses an injection molding machine with a modified nozzle to spray the plastic material. In this study, temperature, pressure, and nozzle size were factors that influenced the success of this spraying method. The method of spraying in this study proved spraying without a gas is possible, a …
Effects Of Reclaimed Asphalt Pavement On Mechanical Properties Of Base Materials, Dane A. Cooley
Effects Of Reclaimed Asphalt Pavement On Mechanical Properties Of Base Materials, Dane A. Cooley
Theses and Dissertations
Reuse of reclaimed asphalt pavement (RAP) in the full-depth recycling (FDR) process is a cost-effective and environmentally responsible method of asphalt pavement reconstruction. Although FDR has been used for several years in some locations, the effect of RAP on the mechanical properties of recycled base materials has not been well documented. The purpose of this research was to investigate the influence of RAP on the mechanical properties of recycled base materials typical of northern Utah. Two sources of RAP, two sources of base, and RAP contents of 0, 25, 50, 75, and 100 percent were utilized in a full-factorial experimental …
Development Of Commercial Applications For Recycled Plastics Using Finite Element Analysis, Nanjunda Narasimhamurthy
Development Of Commercial Applications For Recycled Plastics Using Finite Element Analysis, Nanjunda Narasimhamurthy
Theses and Dissertations
This thesis investigates the suitability of thermo-kinetically recycled plastics for use in commercial product applications using finite element analysis and statistics. Different recycled material blends were tested and evaluated for their use in commercial product applications. There are six different blends of thermo-kinetically recycled plastics used for testing and CATIA is used for finite element analysis. The different types of thermo-kinetically recycled plastics blends are: pop bottles made of PolyethyleneTeraphthalate (PET), milk jugs made of High-Density Polyethylene (HDPE), Vinyl seats made of Poly Vinyl Chloride (PVC) and small amount of Polypropylene (PP) and Urethane, electronic scrap made of engineering resins …
An Automated Three-Dimensional Unstructured Mesh Generation Algorithm For Groundwater Modeling, James Edward Greer
An Automated Three-Dimensional Unstructured Mesh Generation Algorithm For Groundwater Modeling, James Edward Greer
Theses and Dissertations
This thesis describes a new method to create three-dimensional finite element meshes using the horizons to mesh algorithm. The algorithm uses available geologic data and user-defined inputs to guide the mesh generation process. This new approach allows for material layer pinch outs and many different layer refinement options to create well-formed elements that better represent hydrogeologic formations. Two case studies are presented that demonstrate the application of the algorithm's options and capabilities. A graphical interface for the algorithm was developed in the Groundwater Modeling System.
Heavy Metal Adsorption On Iron Oxide And Iron Oxide-Coated Silica : Macroscopic, Spectroscopic, And Modeling Studies, Ying Xu
Dissertations
To accurately model metal mobility and bioavailability in soils and sediments, systematic sorption studies are needed using representative and well-characterized minerals. Two important surfaces are iron oxide and silica, which are ubiquitous and associated with one another in the environment playing important roles in metal distribution. The objectives of this research are to develop models for predicting speciation and mobility of toxic trace metal ions in groundwater, soils, and sediments when competing ions are present. A model system for soils and sediments, iron oxide-coated silica, was synthesized; the degree of coatings was highly sensitive to the particle size of silica …
Optimal Speed Limit For Shared-Use Roadways, Yongqiang Yang
Optimal Speed Limit For Shared-Use Roadways, Yongqiang Yang
Dissertations
Motor vehicle crashes are a serious social problem in the United States. Each year a large number of motor vehicle crashes occur and many people are killed or injured, resulting in substantial economic costs. To minimize economic costs, it is necessary to determine optimal speed limits on roadways because of the strong relationship among posted speed limit, crash frequency, and crash injury severity.
A comprehensive literature review about the relationship among posted speed limit, crash frequency, and crash injury severity level was conducted. Crash frequency prediction models and crash injury severity models are developed to obtain crash frequency and injury …
Refining And Expanding The Feature Stamping Process, Russell N. Emery
Refining And Expanding The Feature Stamping Process, Russell N. Emery
Theses and Dissertations
The accuracy of numerical models analyzing hydrologic and hydraulic processes depends largely on how well the input terrain data represents the earth's surface. Modelers obtain terrain data for a study area by performing surveys or by gathering historical survey data. If a modeler desires to create a predictive model to simulate the addition of man-made features such as channels, embankments and pits, he must modify the terrain data to include these features. Doing this by hand is tedious and time consuming. In 2001 Christensen implemented a tool in the Surface-water Modeling System (SMS) software package for integrating man-made geometric features …
Characterization Of Recycled Concrete For Use As Pavement Base Material, Brandon J. Blankenagel
Characterization Of Recycled Concrete For Use As Pavement Base Material, Brandon J. Blankenagel
Theses and Dissertations
The use of recycled concrete material (RCM) as pavement base material is a promising but unproven technique for road rehabilitation and construction. A telephone survey conducted to investigate the state of the practice concerning RCM usage in Utah County revealed that RCM is infrequently used in this application due primarily to a lack of practical knowledge about the engineering properties of the material. Therefore, this research was aimed at evaluating the physical properties, strength parameters, and durability characteristics of both demolition and haul-back sources of RCM available in Utah County for use as pavement base material. The study included extensive …
Assessing Construction Management Higher Education Strategies: Increased Demand, Limited Resources, And Over-Enrollment, Kristen Lea Wynn
Assessing Construction Management Higher Education Strategies: Increased Demand, Limited Resources, And Over-Enrollment, Kristen Lea Wynn
Theses and Dissertations
The purpose of this research was to see how Baccalaureate Construction Management Programs accredited by the American Council for Construction Education (ACCE) were managing increased enrollments within their programs. The review of literature identified related topics, comparable studies, and relevant issues surrounding over-enrollment. Forty-nine of the 53 accredited ACCE programs responded to the survey instrument. Over two-thirds of the respondents stated that they were either approaching, or were at the limits of enrollment capacities. Most of the respondents listed limited enrollment, the use of adjunct faculty, and funding from industry as leading strategies for managing or obtaining resources. Because CM …
Development Of A Frost Heave Test Apparatus, Russell David Lay
Development Of A Frost Heave Test Apparatus, Russell David Lay
Theses and Dissertations
Frost heave damage to roadways costs millions of dollars every year. The need for an improved understanding of the fundamental mechanisms associated with frost heave and methods for efficiently improving frost-susceptible materials prompted the Department of Civil and Environmental Engineering at Brigham Young University (BYU) to undertake a project to design, construct, and verify the functionality of a new frost heave testing apparatus. Frost heave research has been carried out for more than 75 years. The equipment used to conduct this testing has advanced in accuracy and utility over the years. To establish a background in past and current frost …
Floating Wim Threshold Concept For Truck Weight Enforcement, Zhongren Gu
Floating Wim Threshold Concept For Truck Weight Enforcement, Zhongren Gu
Doctoral Dissertations
Weigh stations are the primary weight compliance checkpoints for commercial trucks. In the past several decades, states have used weigh-in-motion (WIM) technology to reduce delay and increase enforcement on overweight vehicles. This study offers a detailed analysis of weigh station systems and presents floating-threshold algorithms to improve the efficiency of WIM equipped weigh stations.
This research evaluates weigh station design and operational parameters using queueing theory and found that WIM technology not only enhances the effectiveness and efficiency of weigh station operations but also largely reduces travel delay for trucking companies. The effects of truck demand, truck weight distribution, static …
Application Of Statistical Methods And Process Models For The Design And Analysis Of Activated Sludge Wastewater Treatment Plants (Wwtps), Jinsheng Huo
Doctoral Dissertations
The purpose of this study is to investigate statistical procedures to qualify uncertainty, and explicitly evaluate its impact on wastewater treatment plants (WWTPs). The goal is to develop a statistical-based procedure to design WWTPs that provide reliable protection of water quality, instead of making overly conservative assumptions and adopting empirical safety factors. An innovative Monte Carlo based procedure was developed to quantify the risk of violating effluent as a function of various design decisions. A simulation program called StatASPS was developed to conduct Monte Carlo simulations combined with the ASM1 model.
A random influent generator was developed to describe the …
Freeway Crash Prediction Models For Long-Range Urban Transportation Planning, Vasin Kiattikomol
Freeway Crash Prediction Models For Long-Range Urban Transportation Planning, Vasin Kiattikomol
Doctoral Dissertations
The need for safety assessment tools for long-range transportation planning was not seriously recognized until the Transportation Equity Act for Twenty First Century (TEA-21) established a requirement related to safety considerations in the planning process of Metropolitan Planning Organizations (MPO). Currently, most MPOs do not assess the safety consequences of alternative transportation systems. The goal of this dissertation is to develop practical tools for assessing safety consequences of freeways in the context of long-range urban transportation plans. Data for freeway segments and crashes were obtained from North Carolina Department of Transportation and Tennessee Department of Transportation. Three different modeling approaches …
Evaluation Of Experimental Bridge: Massman Drive Bridge Over Interstate 40 In Davidson County, Jeremy Glen Pettus
Evaluation Of Experimental Bridge: Massman Drive Bridge Over Interstate 40 In Davidson County, Jeremy Glen Pettus
Masters Theses
The Massman Drive Bridge is a 284ft. two-span continuous steel bridge over Interstate 40 in Nashville, TN. The bridge is an experimental design that unifies the construction economy of simple span bridges and the structural economy of continuous span bridges. The structural system involves bridge girders initially erected with simple supports at the center bent and abutments.
Before the deck is placed, an experimental connection is used to rigidly connect the two adjacent girders over the center bent. The experimental connection couples a cover plate in tension and two kicker wedge plates in compression. The kicker wedge plates supply resistance …
Alkali Silica Reaction In Virgin And Recycles Aggregates: State Of The Art And Experimental Investigation Using Astm C 1260 And The Staining Method, Shadi Sami Bajjali
Alkali Silica Reaction In Virgin And Recycles Aggregates: State Of The Art And Experimental Investigation Using Astm C 1260 And The Staining Method, Shadi Sami Bajjali
Masters Theses
Alkali silica reaction (ASR) is one of the most prevalent causes of concrete deterioration worldwide. A study done in 1995 showing the impact of ASR on structures stated that 104 concrete dams and spillways, massive concrete structures, have been damaged by alkali silica reaction up to date. Since its discovery by Stanton (1940), there has been significant research on ASR, and major advances have been made in understanding the mechanism underlying ASR-induced expansion and in developing methods of preventing ASR in new and existing concrete through proper measures including proper materials selection and mixture proportioning.
This thesis summarizes the findings …
Modeling And Analysis Of The Dupont Access Bridge, Naiyu Wang
Modeling And Analysis Of The Dupont Access Bridge, Naiyu Wang
Masters Theses
This thesis evaluates the lateral wheel load distribution on a two-span experimental highway bridge, examines the continuity of the superstructure over the center pier, and investigates the connection between bridge girders and abutments. Simplified finite element models of the bridge superstructure with different boundary conditions were made during the research to simulate the bridge behavior and verify the field data. Live load distribution factors for moment from the model with a rotational spring connection between bridge girders and abutment correlated well with factors from field measurements, and they were compared with factors from other methods currently in use such as …
Analytical Verification Of The Aci Approach Of Estimating Tensile Strain Capacity Of Mass Concrete, Cristina Diane Seay
Analytical Verification Of The Aci Approach Of Estimating Tensile Strain Capacity Of Mass Concrete, Cristina Diane Seay
Masters Theses
Mass concrete fill is being used for the support of a facility foundation in Oak Ridge, Tennessee. The facility design requires the support foundation to be relatively crack-free in order to attain the shear wave velocity of 6000 fps, which is necessary for acceptable structural behavior during a design basis earthquake. Specifications were developed for use during construction of the support foundation to ensure that the mix design, sequential placement, and curing are performed to standards that would best ensure a relatively crack-free product. The mix design and subsequent placement strategy were developed by using an American Concrete Institute (ACI) …