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Articles 481 - 510 of 654

Full-Text Articles in Civil and Environmental Engineering

Robust Design And Monitoring Tools For Sustainable And Resilient Structural Design And Infrastructure Management, Sarah Dalton Dec 2011

Robust Design And Monitoring Tools For Sustainable And Resilient Structural Design And Infrastructure Management, Sarah Dalton

All Theses

Structural systems are subject to inherent uncertainties due to the variability in many hard-to-control `noise factors' that include but are not limited to external loads, material properties, and construction workmanship. Two design methodologies have been widely accepted in the practicing engineering realm to manage the variability associated with operational structures: Allowable Stress Design (ASD) and Load and Resistance Factor Design (LRFD). These traditional approaches explicitly recognize the presence of uncertainty; however, they do not take robustness against this uncertainty into consideration. Overlooking this robustness against uncertainty in the structural design process has two drawbacks. First, the design may not satisfy …

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Development And Application Of A Three-Dimensional Probabilistic Wind-Borne Debris Trajectory Model, James Grayson Dec 2011

Development And Application Of A Three-Dimensional Probabilistic Wind-Borne Debris Trajectory Model, James Grayson

All Theses

This research presents a probabilistic debris trajectory model adapted from current 6-degree-of-freedom (6-DoF) deterministic models, in which the aleatoric (inherent) uncertainty is explicitly considered in the proposed probabilistic model. While the inherent randomness in the debris flight trajectory is irreducible due to the wind turbulence, variation in wind direction, gustiness of the wind event and so forth, the proposed probabilistic model seeks to address these uncertainties through Monte Carlo simulations with the appropriate statistical distributions applied to the governing equations of motion of the debris. Verification of the probabilistic debris trajectory model is performed through an analytical and visual comparison …

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Temporal Pier Scour Evolution Under Stepped Hydrographs, Mark Schillinger Dec 2011

Temporal Pier Scour Evolution Under Stepped Hydrographs, Mark Schillinger

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The present study was aimed at measuring the scour hole profile at bridge piers under clear water scour. Scour tests were performed under both steady state flow and under stepped hydrographs. Multiple smaller flood events were run to determine how flood history affects scour hole development. Various equilibrium scour depth equations and proposed temporal scour models were compared. The similarity of the scour hole profiles with time and flow history were evaluated.
Experiments were conducted in a 14.8 m long, 1.19 m wide, 1.22 m deep rectangular flume with a model bridge pier. A uniform sediment bed (d50= …

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Analysis And Parameterization Of The Flight Of Ember Generation Experiments, Hillary Harris Dec 2011

Analysis And Parameterization Of The Flight Of Ember Generation Experiments, Hillary Harris

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This thesis presents a study on ember flight modeling based on a series of wind tunnel experiments. The purpose of these experiments and the data collected was to provide the input conditions for an ember flight model in order to compare and validate the model predictions. An analysis was performed which determined the sensitivity of model predictions of downwind mass distribution to uncertainties in the model input parameters.
From the wind tunnel experiments, flight distances were measured and characteristic ember size distributions were obtained from the collected data. A flight model was developed based on standard models published in the …

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Influence Of Warm Mix Additives Upon High Rap Asphalt Mixes, William Rogers Dec 2011

Influence Of Warm Mix Additives Upon High Rap Asphalt Mixes, William Rogers

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This study was conducted to determine the effect of warm mix (WMA) modifiers on asphalt mixes containing high percentages of reclaimed asphalt pavement (RAP). Mixes were created using three aggregate sources, four RAP percentages (0%, 20%, 35%, and 50%), and three warm mix modifiers (HMA, zeolite, and Sasobit®). Base binders from the same source (PG 64 -22, 58 -28, 52 -28) and one rejuvenator were used for each mix to ensure the final blended binder grade was at least PG 64 -10.
Specimens were created at HMA or suggested WMA temperatures and tested for rut depth, indirect tensile strength (ITS), …

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Influence Of Pavement Type On Near Surface Air Temperature, David Duncan Dec 2011

Influence Of Pavement Type On Near Surface Air Temperature, David Duncan

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Effects from an Urban Heat Island (UHI) can be detrimental to the world as a whole. This study examines a collection of permeable and conventional pavements in South Carolina to determine how they relate to near surface air temperatures, which is an indicator of the UHI impact of an area. Three locations were used, each with a different selection of pavement type. Permeable and conventional forms of both asphalt and concrete were tested, as were some open graded friction course samples. Air temperatures were measured and recorded from the pavement surface up to an elevation of 60-in.
Multiple days of …

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Probabilistic Approaches To Stability And Deformation Problems In Braced Excavation, Zhe Luo Dec 2011

Probabilistic Approaches To Stability And Deformation Problems In Braced Excavation, Zhe Luo

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This dissertation is aimed at applying probabilistic approaches to evaluating the basal-heave stability and the excavation-induced wall and ground movements for serviceability assessment of excavation in clays. The focuses herein are the influence of spatial variability of soil parameters and small sample size on the results of the probabilistic analysis, and Bayesian updating of soil parameters using field observations in braced excavations.
Simplified approaches for reliability analysis of basal-heave in a braced excavation in clay considering the effect of spatial variability in random fields are presented. The proposed approaches employ the variance reduction technique (or more precisely, equivalent variance method) …

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Fluid Mud Underflows In Coastal Dredge Disposal, Mijanur Chowdhury Dec 2011

Fluid Mud Underflows In Coastal Dredge Disposal, Mijanur Chowdhury

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This manuscript presents the results of a thorough theoretical and experimental investigation on fluid mud underflows generated in a typical coastal dredge disposal operation. The main goal of this investigation is to understand the propagation dynamics of fluid mud underflows that depends upon a number of factors, including: concentrations, rheological properties and released configurations of fluid mud. Laboratory experiments were conducted with different initial fluid mud concentrations in three different experimental set-ups: rectangular flume for constant volume release, rectangular flume for constant flux release, and a square pool for radial constant flux release of fluid mud. The experiments in the …

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A History-Dependent Nonwetting Phase Trapping Model For Multiphase Flow Characteristic Curves, Christopher Patterson Aug 2011

A History-Dependent Nonwetting Phase Trapping Model For Multiphase Flow Characteristic Curves, Christopher Patterson

All Theses

Characteristic curves used in numerical multiphase flow simulators describe relative permeability-saturation and capillary pressure-saturation relationships for flow simulations. Characteristic curves are typically non-hysteretic; meaning they are monotonic functions of saturation and are limited to a single value for residual saturation. Implications of residual saturation are important for environmental, petroleum, and geologic carbon sequestration modeling. However, hysteretic characteristic curves predict that trapped residual saturation depends on the local saturation history. The use of hysteretic characteristic curves is critical to predicting the residual saturation and ultimately the mobility of a nonwetting phase such as supercritical CO2 or a nonaqueous phase liquid (NAPL). …

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Influence Of Natural Organic Matter On Plutonium Sorption To Gibbsite, Laura Simpkins Aug 2011

Influence Of Natural Organic Matter On Plutonium Sorption To Gibbsite, Laura Simpkins

All Theses

Understanding plutonium geochemical behavior is imperative to the development of schemes for remediation of plutonium environmental contamination and accurate assessment of risks posed by the disposal of plutonium bearing wastes. The primary mechanism of plutonium mobility in the environment is subsurface transport. The mobility of plutonium is significantly influenced by redox and complexation reactions. Although the effects of surface mediated redox reactions on plutonium's subsurface mobility have been previously documented, little has been done to determine the impact of organic materials on sorption behavior and oxidation states. To adequately predict the behavior of plutonium in the environment, the influence of …

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Determination Of Freshwater Algal Biomass And Sulfolipid Content As Functions Of Inorganic Carbon Treatment, Melissa Morella Aug 2011

Determination Of Freshwater Algal Biomass And Sulfolipid Content As Functions Of Inorganic Carbon Treatment, Melissa Morella

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Cultures of mixed freshwater algae were grown in open batch reactors made up of modified BG-11 media that contained 0, 25, 50 or 100% of the suggested inorganic carbon content (0, 0.5, 0.1 and 0.2 g/L Na2CO3) to assess the subsequent production of the high-value product, sulfoquinovosyl diacylglycerol (SQDG). After 25 days of growth, the reactors were composed of primarily Oscillatoria growth. All four reactors exhibited a trend of increasing biomass and alkalinity with time, and an initial increase then decrease in pH. The total inorganic carbon (TIC) in all reactors exhibited a mirrored, opposite trend …

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Structural Health Monitoring Of Historic Masonry Monuments, Saurabh Prabhu Aug 2011

Structural Health Monitoring Of Historic Masonry Monuments, Saurabh Prabhu

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Structural Health Monitoring (SHM) is a well-accepted diagnostic technique being used to evaluate modern structures. This method involves monitoring the vibration response of a structure to detect changes in its structural state. The primary intention of this thesis is to address two practical and technical difficulties encountered in deploying SHM on historic masonry monuments: (i) the selection of suitable low dimensional vibration response features that are highly sensitive to the presence and extent of damage, while having low sensitivity to extraneous noise and (ii) the selection of optimal sensor locations for efficient system identification applied to Gothic Cathedrals. Both of …

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Retrofit Solutions For Sealed Pervious Concrete Pavements, Gregory Bunting Aug 2011

Retrofit Solutions For Sealed Pervious Concrete Pavements, Gregory Bunting

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The goal of this research was to design, implement, and evaluate several retrofit solutions for sealed pervious concrete. Properly functioning pervious concrete pavements allow water to drain through the structure, eliminating the need for traditional drainage infrastructure. A recent study of South Carolina porous pavements (Putman 2010) revealed that some pervious concrete pavements are not properly draining, either because of sealing at the surface. Sealed pavements are generally a result of construction processes, and sealed pavements cannot be fixed with sediment removal techniques such as vacuuming and pressure washing. This study investigates a technique to increase infiltration of sealed pervious …

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Sensitivity Analysis Of Load Distribution In Light-Framed Wood Roof System Due To Typical Modeling Parameters, Ranjith Shivarudrappa Aug 2011

Sensitivity Analysis Of Load Distribution In Light-Framed Wood Roof System Due To Typical Modeling Parameters, Ranjith Shivarudrappa

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Since failure of roof systems in past high wind events have demonstrated the consequences of not maintaining a continuous load path from the roof to the foundation, many studies have been conducted to better understand this load path, including how loads are distributed in the system. The present study looks to add to the current knowledge of the vertical load path by focusing on uplift loads and by considering the sensitivity of different modeling parameters. This is done by developing and assessing load influence coefficients for various roof-to-wall (RTW) connections. An analytical model of a light-framed wood structure using finite …

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Evaluation Of Warm Mix Open Graded Friction Course Mixtures, James Wurst Aug 2011

Evaluation Of Warm Mix Open Graded Friction Course Mixtures, James Wurst

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The goal of this study was to evaluate EvothermTM (a chemical package) and foaming (a water-injection method) warm mix asphalt (WMA) technologies to determine their effectiveness in producing high quality open graded friction course (OGFC) mixes. Specifically, this study focused on the effect of the removal of stabilizing additives (fibers and polymers) on the optimum binder content and performance of WMA OGFC mixtures. By focusing on additive removal, this study attempted to evaluate practical production concerns and the possible benefits of WMA technologies combined with OGFC.
The EvothermTM WMA and foaming WMA mixes were compared to traditional HMA OGFC by …

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Behavior Of The Next-D Beam Shear Key: A Finite Element Approach, Armando Flores Aug 2011

Behavior Of The Next-D Beam Shear Key: A Finite Element Approach, Armando Flores

All Theses

State Departments of Transportation have been using adjacent precast bridges for many years. A vital component of this type of bridges is the connection between the members, which is typically done with a grouted shear key. Shear keys have changed through time to adapt to the requirements of bridge design. An assessment of the Northeast Extreme Tee with integral deck (NEXT-D) was performed for the SCDOT as a development possibility for short span bridges. This research focuses on the finite element analysis study of the NEXT-D's specific shear key configuration.
A review of shear key configurations used by different DOTs …

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Contaminant Mass Transfer During Boiling In Fractured Geologic Media, Fei Chen Aug 2011

Contaminant Mass Transfer During Boiling In Fractured Geologic Media, Fei Chen

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Remediation of fractured geologic media contaminated with chlorinated volatile organic compounds that diffuse into the matrix is challenging using isothermal methods. Due to the low permeability of the matrix material and uncertainty of fracture networks, it is difficult to flush the system with any type of fluid or deliver remediation agents into the matrix. However, thermal methods have some promises. When the matrix is heated above water boiling temperature, depressurization in the fractures may trigger water boiling in the matrix, which, as a result, generates a large volumetric steam flow toward adjacent fractures, stripping the adsorbed or dissolved volatile contaminants …

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An Experimental And Computational Study Of Windborne Debris In Severe Storms, Arash Karimpour Aug 2011

An Experimental And Computational Study Of Windborne Debris In Severe Storms, Arash Karimpour

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Abstract
This research focuses on an experimental and theoretical investigation of windborne debris emanating from loose gravel on built-up roofs. During severe storms, windborne debris can cause considerable physical harm and property damage. One of the major sources of flying debris in large commercial areas is loose gravel on built-up roofs. Such loose gravel can be responsible loss of life and significant property damage. Despite the high risk of windborne debris, their flight mechanics are poorly understood. To better understand windborne debris flight, a series of experiments were conducted in the Clemson University Boundary Layer Wind Tunnel. These experiments were …

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The Effects Of Fundamental Mixture Parameters On Hot-Mix Asphalt Performance Properties, Wenbin Zhao Aug 2011

The Effects Of Fundamental Mixture Parameters On Hot-Mix Asphalt Performance Properties, Wenbin Zhao

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Asphalt pavements are composed of three components: aggregate, asphalt binder, and air. In the process of plant production and on-site construction, the construction quality can vary in the three component and the variability can further affect a pavement's future performance.. This research identifies aggregate gradation, binder content, and air voids content as the fundamental parameters. Understanding the fundamental parameters' influence on the HMA mixture's performance properties can provide valuable information on how to improve the current quality insurance practice. The objective of this study is to conduct well-controlled experiments to investigate how mix gradation, air voids and small range binder …

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Social Sustainability Considerations During Planning And Design: A Framework Of Processes For Construction Projects, Rodolfo Valdes Vasquez Aug 2011

Social Sustainability Considerations During Planning And Design: A Framework Of Processes For Construction Projects, Rodolfo Valdes Vasquez

All Dissertations

With increased awareness of issues such as global resource shortages and climate change, sustainability efforts are becoming more common in the construction industry. While these efforts often consider economic and environmental factors, a truly sustainable construction project also needs to include such social considerations as its impact on the surrounding community and the safety, health, and education of the workforce. For the construction industry, social sustainability requires integrating processes for improving safety, health and well-being over the project life cycle. However, an empirical and comprehensive framework defining these social sustainability processes in construction projects has yet to be clearly delineated. …

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Investigation Into The Role Of Airfield Pavement Deicer In Concrete Pavement Deterioration, David Wingard Aug 2011

Investigation Into The Role Of Airfield Pavement Deicer In Concrete Pavement Deterioration, David Wingard

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Premature deterioration of concrete due to materials-related distresses has been observed with increased frequency in airfield pavements across the United States in the past two decades. The use of a new breed of deicing chemicals based on alkali-acetates and alkali-formates, starting in the early 1990s, has been suspected to be one of the significant reasons for the increase in the observed deterioration. Previous laboratory-based studies have found that the early-age deterioration in concrete is associated with exposure to deicers causing acceleration of the Alkali Silica Reaction (ASR) deterioration mechanism and consequent failure. However, no systematic forensic studies on the impact …

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Fate And Transport Of Escherichia Coli Within Sediment Basins On Active Construction Sites, Elizabeth Tempel May 2011

Fate And Transport Of Escherichia Coli Within Sediment Basins On Active Construction Sites, Elizabeth Tempel

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The conventional method of controlling sediment-laden runoff on construction sites is the use of sediment basins. These basins slow the velocity of runoff and allow the particles to settle from the water column before discharge to surface waters offsite. This best management practice, however, may create a reservoir for pathogenic bacteria. Sediment is known to provide protection for bacteria; therefore, while these basins decrease sediment loadings to water bodies downstream, they may introduce harmful levels of pathogenic bacteria into these surface waters. In addition to causing human health risks, these high bacteria levels alter natural biological makeup of downstream ecosystems. …

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Applications Of Moderate-Resolution Remote Sensing Technologies For Surface Air Pollution Monitoring In Southeast Asia, Arika Bridhikitti May 2011

Applications Of Moderate-Resolution Remote Sensing Technologies For Surface Air Pollution Monitoring In Southeast Asia, Arika Bridhikitti

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Retrievals from Earth observation satellites are widely used for many applications, including analyzing dynamic lands and measuring atmospheric components. This research aims to evaluate appropriateness of using satellite retrievals to facilitate understanding characteristics of Southeast Asian (SEA) surface air pollution, attributed to regional biomass burnings and urban activities. The studies in this dissertation focused on using satellite retrievals for 1) mapping potential SEA air pollution sources; which are forests, rice paddies, and urban areas, 2) understanding dynamic optical characteristics of SEA biomass-burning aerosols, and 3) inferring surface ozone level. Data used in this study were from three NASA's Earth Observing …

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Identification And Characterization Of Polychlorinated Biphenyl Dechlorinating Microorganisms From Lake Hartwell, Sc, Tess Brothersen May 2011

Identification And Characterization Of Polychlorinated Biphenyl Dechlorinating Microorganisms From Lake Hartwell, Sc, Tess Brothersen

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To date, all attempts to isolate PCB dechlorinators using traditional isolation techniques have failed. In addition, the study of PCB dechlorinating organisms has been hampered because researchers were unable to grow the organisms in sediment-free, defined media. Three microbial species capable of reductive dechlorination of polychlorinated biphenyls have been identified. These three species are from two phylogenetically distinct branches, Dehalococcoides (Bedard et al., 2007) and the DF-1/o-17 group (Wu et al., 2002a; Cutter et al., 2001). The three cultures from which polychlorinated biphenyl dechlorinators have been identified used similar strategies to 'wean' the microbes from the sediments. In this research, …

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Wave Reflection Characteristics Of Permeable And Impermeable Submerged Trapezoidal Breakwaters, Mathew Hornack May 2011

Wave Reflection Characteristics Of Permeable And Impermeable Submerged Trapezoidal Breakwaters, Mathew Hornack

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The present study aims to quantify reflection coefficients in the vicinity of impermeable and permeable submerged trapezoidal breakwaters. Three impermeable breakwater models are tested, each with a unique side slope for the breakwater faces. Two permeable models are tested, one made of PVC pipe and the other consisting of golf balls contained within a mesh cage, to provide two separate porosities. Testing is carried out at the Clemson University Flow Physics Laboratory in a laboratory wave tank with the inclusion of a 1:20 sloping sandy beach to simulate natural environmental conditions. Wave elevations are collected during experiments by two capacitance …

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Predictive Modeling Of Wind Turbine Blades, Kendra Van Buren May 2011

Predictive Modeling Of Wind Turbine Blades, Kendra Van Buren

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Wind turbine blades are being produced at a larger scale in order to meet demands from the burgeoning U.S. wind energy industry, and are forecasted to only grow larger for off-shore applications. Modeling and Simulation (M&S) provides a cost and time efficient alternative when studying the structural behavior of blades such as for loading conditions that are too difficult to replicate in laboratory conditions, and for various severity of damage in wind turbine blades. For this reason, M&S will continue to play an indispensible role in understanding the behavior of wind turbine blades and is gradually replacing the traditional test, …

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A Finite Element Model For Coupled Deformation-Flow Analysis Of Unsaturated Soil-Structure Systems And Its Validation, Hadakopan Krishnapillai May 2011

A Finite Element Model For Coupled Deformation-Flow Analysis Of Unsaturated Soil-Structure Systems And Its Validation, Hadakopan Krishnapillai

All Dissertations

The unsaturated soil mechanics is one of the emerging fields that require extensive studies to understand its behavior under various loading and environmental conditions. Unsaturated soil consists of three bulk phases: solid, liquid and gas and three interfaces: solid-liquid, liquid-gas and gas-solid. It is generally accepted that the interaction among various bulk phases and interfaces has to be taken into account in the characterization of unsaturated soils. The behavior of soil-structure systems is complex and the complexity further increases when the structure is located in unsaturated soil. Numerical methods such as the finite element method are ideally suited for elucidating …

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Effect Of Selected Parameters On Aggregate Reactivity In Accelerated Mortar Bar Test Method: Aggregate Size & Deicers, Sujay Math May 2011

Effect Of Selected Parameters On Aggregate Reactivity In Accelerated Mortar Bar Test Method: Aggregate Size & Deicers, Sujay Math

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Abstract
Alkali Silica Reaction (ASR) is a chemical reaction between reactive siliceous aggregates and the alkali hydroxides present in the pore solution of hydrated cement paste in concrete. The chemical reaction produces ASR gel that is hygroscopic in nature and is volumetrically unstable in the presence of moisture. Expansion resulting from the swelling of the gel creates tensile stresses in the concrete leading to cracking and distress.
While ASR distress has been known to occur in concrete for over last 70 years, there has been an increase in the frequency of this distress in recent years. This is primarily due …

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Evaluation Of Manganese Control In The Source Water And Microfiltration Plant Of A South Carolina Water Utility, Daniel Lewis May 2011

Evaluation Of Manganese Control In The Source Water And Microfiltration Plant Of A South Carolina Water Utility, Daniel Lewis

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Although present in most water supplies, manganese is a difficult-to-treat nuisance contaminant in drinking water. The US Environmental Protection Agency (EPA) has set a Secondary Maximum Contaminant Level (SMCL) of 0.05 mg/L but experts have recommended a goal of 0.02 mg/L or less to avoid chronic issues with the metal. This work is a report on manganese control for the Startex-Jackson-Wellford-Duncan (SJWD) Water District, a water utility in northwestern SC. Fourteen locations were sampled from June 2010 through October 2011. Manganese, iron, dissolved organic carbon, dissolved oxygen, and other relevant parameters were measured.
The lake-fed Middle Tyger River is the …

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Probablistic Assessment Of Roof Uplift Capacities In Low-Rise Residential Construction, Bagyalakshmi Shanmugam May 2011

Probablistic Assessment Of Roof Uplift Capacities In Low-Rise Residential Construction, Bagyalakshmi Shanmugam

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Post hurricane damage investigations of light frame wood residential structures reveal that roof envelope failure induces considerable damage to the structure and its contents. Roof - to - wall (RTW) connection failures though not as common as roof sheathing failure also cause significant structural and material damage. Considerable changes have been made in the ASCE structural loads standard and International Building code (IBC) after hurricane Andrew in order to prevent RTW connection and sheathing failures. That includes not only a substantial increase in the design wind load in the past two decades but also a strict enforcement of tighter nailing …

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