Digital Commons Network^™

Nondestructive Evaluation Of Corrosion Damage In Reinforced Concrete Aged Slab Specimen, Rawya Abdulsattar Abduljabbar

Theses and Dissertations

The deterioration of concrete bridge decks presents a maintenance challenge for most transportation agencies and bridge owners. This problem increases during the freeze-thaw cycle. De-icing salts can accelerate the deterioration process. Corrosion of steel reinforcement in reinforced concrete structures is considered a dominant factor causing premature deterioration, especially those structures located in a coastal environment. The resulting corrosion product produced has several times the volume of steel, resulting in cracking of the concrete cover if the corrosion is significant. In this study, a bridge deck specimen was subjected to an artificial environment to accelerate the corrosion process. Prior to this …

Hydrothermal Carbonization Of Food Waste For Nutrient Recovery And Reuse, Ifeolu M. Idowu

Theses and Dissertations

Food waste represents a rather large and currently underutilized source of potentially available and reusable nutrients. Laboratory-scale experiments evaluating the hydrothermal carbonization of food wastes collected from restaurants were conducted to understand how changes in feedstock composition and carbonization process conditions influence primary and secondary nutrient fate. Results from this work indicate that at all evaluated reaction times and temperatures, the majority of nitrogen, calcium, and magnesium remain integrated within the solid-phase, while the majority of potassium and sodium reside in the liquid-phase. The fate of phosphorus is dependent on reaction times and temperatures, with solid-phase integration increasing with higher …

Impact Of Critical Path Method (Cpm) Of Scheduling On On-Time Completion Of Transportation Projects, Fahim Ahmed

Theses and Dissertations

This study addresses the effectiveness of Critical Path Method (CPM) scheduling on project delivery. Specifically, the on-time completion of projects with and without a CPM schedule is explored. The paper uses data from 2,097 South Carolina transportation projects let after February 2008 and substantially completed by August 2015. The delay analysis uses the original contract completion date as well as the completion date adjusted by change orders. Chi-Squared tests are used to examine the relationship between CPM scheduled projects and delayed projects, and t-tests are used to compare the mean delay (in days) between CPM scheduled and unscheduled projects. The …

Reducing Model Selection Computational Cost By Metamodeling The Evidence, Ramin Madarshahian

Theses and Dissertations

Modeling is an abstraction of reality that lets a designer or engineer perform simulations with a “real” object or structure without testing it physically. However, the result of simulations is as good as their models. Selecting the best model among many candidates is another challenge.

Complex models could translate into more accurate predictions, but they also require larger computational effort. The Bayes factor is often used to compare different models considering the data and analyst’s experience. To obtain the Bayes factor, the Bayesian model evidence is calculated; however, calculating the Bayesian model evidence of computationally expensive models is not a …

Low-Cost Fishing Net-Reinforced Cement Matrix Overlay For Substandard Concrete Masonry In Coastal Areas, Mohammed A. Mousa

Theses and Dissertations

The aim of this project is to investigate a novel and affordable option to externally strengthen substandard concrete masonry (CM) walls for out-of-plane loads (e.g., high winds and flying debris). Two types of strengthening materials for fiber-reinforced cement mortar (FRCM) overlays are investigated; namely, fishing net (FN) and welded wire steel mesh (WWSM) reinforcements.

Salient mechanical properties of representative materials including substandard concrete masonry unit (CMU) blocks, mortar, nylon FN and WWSM reinforcements, and FRCM composite, were experimentally characterized. A simple bilinear model is proposed to describe the tensile behavior of the FRCM composite. An analytical model was then used …

Investigating The Feedstock Properties And Process Conditions Influencing The Characteristics Of Products Generated From The Hydrothermal Carbonization Of Organic Feedstocks, Liang Li

Theses and Dissertations

Hydrothermal carbonization (HTC) is a novel environmentally beneficial thermal conversion process for the transformation of organic feedstocks to value-added products. However, little is known about the role of feedstock properties and/or process conditions during carbonization. This study was conducted to determine the parameters most influential during the HTC of organic feedstocks. Experiments and statistical analyses were conducted to: (1) determine the effect of specific feedstocks, feedstock interactions, and process conditions on carbonization product characteristics; (2) understand how initial liquid characteristics influence product characteristics and evaluate the significance of these initial liquid characteristics in predicting product characteristics; and (3) develop statistical …

Multi-Model Structural Analysis, Wesley Holt

Theses and Dissertations

The uncertainty in modeling earthquake loading is investigated through the comparison of various openSEES models. A series of models is created and the responses compared with each other as well as with a full scale shake table experiment. The openSEES models selected for comparison include two linear models, a nonlinear model using the Steel01 material for the entire cross section, and eight fiber models using reinforcing steel material and various concrete materials.

The models are subjected to a series of nine simulated earthquakes, matching the excitations applied to the shake table test. It is found that all of the models …

Characterization Of Subgrade Resilient Modulus For Mepdg And The Effects On Pavement Rutting, Md Mostaqur Rahman

Theses and Dissertations

In 2008, the American Association of State Highway and Transportation Officials (AASHTO) released a modified pavement design method (i.e., the Mechanistic Empirical Pavement Design Guide (MEPDG)) based on Long Term Pavement Performance (LTPP) data from all over the United States. The MEPDG default design parameters developed from the LTPP database are expected to be significantly different than those for South Carolina material, traffic and weather conditions, thus the default design parameters may not be accurate for South Carolina. Therefore, the new pavement design method should be calibrated for South Carolina conditions by performing MEPDG local calibration.

Different input variables should …

Product Qualification And Performance Assessment Of Hsrm Prestressed Concrete Railroad Ties Through Laboratory Testing, Ali Haider Abdulqader

Theses and Dissertations

This study focuses on the performance assessment of prestressed concrete railroad ties made of a newly developed High Strength Reduce Modulus (HSRM) concrete. The HSRM material has been developed by researchers at the University of South Carolina laboratories. The HSRM material was originally considered as a high-performance concrete for highway bridge girders, but it was rejected because it shows very low modulus of elasticity. A current project at USC proposed to use this HSRM material in prestressed concrete railroad ties. The experimental tests during the material development phase of the project showed that the HSRM-HPC has a reduced Modulus of …

Multiscale Modeling Of Water Transport And The Influence Of Water Quality Parameters On Membrane Processes, Linkel Kwabena Boateng

Theses and Dissertations

Membrane-based desalination processes have become a viable means of producing potable water to meet water resource needs in both industrialized and developing nations. Extensive experimental investigation, in conjunction with computational modeling is critical in the development of sustainable and cost-effective desalination technologies. The overall goal of this dissertation is to develop a multiscale modeling framework to elucidate water and salt transport mechanisms and the influence of water quality parameters on membrane processes. The key tasks involved in this study are: establish a criterion for estimating water flux using Bayesian inference; develop a multiscale framework to connect molecular dynamics (MD) simulations …

Addressing The Impact Of Gavins Point Dam On The Lowermost~1400 Kilometers Of The Missouri River, Gregory Leaphart

Theses and Dissertations

The Missouri River originates in the Rocky Mountains in western Montana and joins the Mississippi River near St. Louis, Missouri. Beginning in the early 1900s, engineering efforts, such as dam construction, channel narrowing, and river alignment, were performed for flood control, navigational purposes, to use of water for agricultural and industrial needs, to produce hydroelectric power and the impounded lakes for recreation. These projects permanently altered the flow and sediment transport regimes in the river and the exchange of sediment with the surrounding floodplain. We focus on the long term effects of dam construction and channel narrowing on approximately the …

Deposits Emplaced In Upper Regime, Ricardo Rafael Hernández Moreira

Theses and Dissertations

Relatively common to the submarine setting are depositional sequences that begin with a lower erosional boundary, followed in ascending order by a either a graded or an inherently massive basal unit, a relatively coarse parallel laminated unit, a cross laminated unit, a relatively fine parallel laminated unit, and a capping layer of massive mud. These sequences are present in turbidity current, coastal storm and tsunami deposits, and their study is the key to understanding the physical processes governing sediment transport, erosion and deposition in submarine settings, to the reconstruction of global paleoclimate and paleoflow, to the exploration of hydrocarbon reservoirs …

Characterization Of Human-Induced Vibrations, Benjamin Thomas Davis

Theses and Dissertations

In the US alone, 20% of citizens will be over the age of 65 by the year 2030, and the largest challenge facing this growing demographic is not a new disease but a simple motion - the fall. These events are the premier cause of fatal and nonfatal injuries. In fact, a fall is so common that every 17 seconds an older adult is treated for fall-related injuries, and every 30 minutes, an older adult dies from fall complications. Research has shown a positive outcome of a fall event is largely dependent on the immediate response (<30 minutes) and rescue of the person.

This work explores …

Use Of Biochar-Ultrafiltration Membrane Processes For Removal Of Humic Acid, Vaibhavi Shankar

Theses and Dissertations

The performance of an ultrafiltration (UF)-biochar process was evaluated in comparison with a UF membrane process for the removal of humic acid (HA). Bench-scale UF experiments were conducted to study the rejection and flux trends under various hydrodynamic, pH, conductivity, and pressure conditions. The resistance-in-series model was used to evaluate the processes and it showed that unlike stirred conditions, where low fouling resistance was observed, comparable trends were obtained for UF-biochar and UF alone for unstirred conditions. Thus, the processes were further evaluated under unstirred conditions. Additionally, total fouling resistance was decreased in the presence of biochar, indicating that HA …

Evaluation Of Concrete Degradation Using Acoustic Emission: Data Filtering And Damage Detection, Marwa A. Abdelrahman

Theses and Dissertations

The prevalence of aging and deteriorating infrastructure in the U.S. has raised concerns regarding its level of serviceability, reliability, and vulnerability to natural disasters. This issue has gained attention recently and efforts are being conducted to accelerate the delivery of enhanced nondestructive testing (NDT) and structural health monitoring (SHM) methods. Acoustic emission (AE) is a strong candidate for these applications due to its high sensitivity and potential for damage detection in different materials. However, several challenges associated with the technique hinder the development of automated, reliable, real-time SHM using AE.

This study aims to advance the use of AE for …

Assessment, Prevention And Remediation Of Corrosion In Weathering Steel Transmission Line Poles, Matthew Bruce Barragan

Theses and Dissertations

Electric utilities routinely use weathering steel (WS) in transmission line structures, capitalizing on corrosion resistance and associated cost savings. The formation of a protective iron-oxide patina on uncoated above-ground WS surfaces depends on the operating environment and exposure conditions. In fact, exposure to common aggressive environments, such as those found in sulfate-contaminated industrial areas and chloride-laden coastal areas, may dramatically hinder the corrosion resistance of WS transmission line structures.

To assess the corrosion behavior of WS transmission line poles, field inspections were conducted at five test sites comprising diverse operating environments and pole designs. These sites included three locations in …

Adaptivity For Meshfree Point Collocation Methods In Linear Elastic Solid Mechanics, Joshua Wayne Derrick

Theses and Dissertations

This study presents the behavior of local node adaptivity for point collocation meshfree numerical methods and its application to linear elastic solid mechanics. A bisection approach to meshfree adaptivity will be presented with numerical examples showing that convergence is achieved. A threshold value is required from the user and this value is an acceptable change in gradient for the problem. If the change in gradient between 2 nodes exceed this limit, a node is added at the mid-point between the two nodes. This process applies to all nodes in the model. Once the refinement is complete, the model is processed …

Experimental Study Of Longitudinal Sorting Of Particles Differing In Size And Density, Nabila Mahjabeen

Theses and Dissertations

Transport, deposition and erosion of sediment particles differing in size, shape and density may result in particle segregation, which in geosciences applications is generally referred to as sediment sorting. A thorough understanding of sediment sorting processes is important to describe and model a wide variety of natural processes such as the decrease in particle size and/or density in a fluvial system (downstream fining and/or lightening), the formation of economic placers, concentration of heavy minerals, chemical and metal pollutants etc. Sorting of sediment grains associated with sediment transport in the streamwise direction results in the development of longitudinal sorting patterns. Vertical …

Drilled Shaft Skin Resistance Design In The Cooper Marl, William J. Gieser

Theses and Dissertations

As drilled shafts have become a more popular foundation type in the Charleston, South Carolina area, there has been an ongoing goal of optimizing drilled shaft design while maintaining the structural integrity of the foundation. In the Charleston area, the primary bearing stratum for deep foundations is the Cooper Marl, a calcareous Oligocene formation. Research performed from 2002 to 2004 on load test data from drilled shafts constructed in the Cooper Marl and soil properties from three test sites for the Cooper River Bridge explored the relationship between the measured skin resistance and geotechnical properties. In the 15 years since …