Engineering Commons^™

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 …

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 …

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 …

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 …

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 …

Confluence Of Density Currents Produced By Lock-Exchange, Hassan Ismail

Theses and Dissertations

Density currents represent a broad classification of flows driven by the force of gravity acting on a fluid with variable density. With examples of density currents including turbidity currents, sand storms, salt wedges in tidal rivers, and oil spills, a great deal of attention has been previously given to understanding the underlying mechanisms of such flows and implications of those flows on fluid, species, and sediment transport. Although documented confluences occur naturally in terrestrial and submarine settings,little attention has been given to understanding the confluence of two density currents.

This study furthers the state of knowledge on density current confluences …

Performance Assessment Of Hsrm Concrete Ties Through Finite Element Model Simulations, Adam I. Zeitouni

Theses and Dissertations

Concrete ties have become a promising alternative to timber ties for freight lines with increased curvature, high annual traffic, and large axle loads. They are also widely adopted in passenger lines. High strength (HS) concrete is the material of choice in the fabrication of prestressed concrete railroad ties. The higher strength of the concrete is directly related to higher values of the Elastic Modulus, thus increasing the rigidity of the material. The combination of increased strength, rigidity, and the material brittleness may lead to the development of high amplitude stresses with high gradients, which appears to be a common underlying …

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 …

Modeling Human-Structure Interaction Using A Controller System, Albert Ricardo Ortiz Lasprilla

Theses and Dissertations

The effects of human loads on structures are difficult to predict because they depend on the type of activity people are performing. However, models for typical activities such as standing, sitting and jumping have been proposed in the literature. Traditional models represent the human body as a system of lumped masses, dampers and springs arranged in a system with multiple degrees of freedom. Arguably, these models might not fully represent the human body because lumped masses, dampers and springs cannot add energy to the overall system. Furthermore, people could react differently to different levels of excitation and other environmental conditions. …

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 …

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 …

Modeling Embankment Breach Due To Overtopping, Ali Asghari Tabrizi

Theses and Dissertations

Despite numerous embankment failures around the world, in-depth assessments as well as reliable, comprehensive sets of data of such failures are limited. Detailed understanding of the earthen embankment failure process and the dominant parameters affecting the failure are needed to predict and model the breach process precisely. Therefore, a series of laboratory experiments on embankment (i.e., dam and levee) overtopping as well as erodibility measurements using the Submerged Jet test are conducted. Also, to study the influence of different model parameters (e.g., turbulence model, bedload formula), one of the dam embankment experiments is simulated. The main goal of this research …

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 …

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 …

Improved Assessment Of The Magnitude And Acceleration Of Prehistoric Earthquakes In The South Carolina Coastal Plain, Emad Gheibi

Theses and Dissertations

Seismically-induced soil liquefaction is one the most hazardous geotechnical phenomenon that can cause loss of life and devastating damage to infrastructure. Proper estimation of critical ground motion parameters (e.g. peak ground acceleration and earthquake magnitude) is vital for seismic design of new structures and retrofit of existing structures, especially in regions such as the South Carolina Coastal Plain (SCCP) where the frequency of re-occurrence of large earthquakes is low (studies of paleoliquefaction features have revealed seven, large, prehistoric earthquakes occurring within the last 6000 years) and the locations of potential sources are not exactly known. Moreover, due to mechanical and …

Numerical And Experimental Investigations Of Dam And Levee Failure, Ezzat Youssef Elhassan Mohamed Elalfy

Theses and Dissertations

Both numerical and experimental investigations are conducted to study the failure of earthen dams and levees. Boussinesq equations describing one-dimensional unsteady flow including non-hydrostatic pressure distribution are solved numerically along with Exner equation for the sediment mass conservation to include the effects of the streamline curvature on the failure of non-cohesive earthen embankments. In addition, the effects of the steep bottom slope on the flow variables during the failure are studied by solving the Saint- Venant equations modified for steep bed slope along with the Exner equation to simulate non-cohesive earthen embankment failure due to overtopping. The Boussinesq equations are …

Assessment Of Classifiers For Potential Voice-Enabled Transportation Apps, Md Majbah Uddin

Theses and Dissertations

Transportation apps are playing a positive role for today’s technology-driven users. They provide users with a convenient and flexible tool to access transportation data and services, as well as collect and manage data. In many of these apps, such as Google Maps, their operations rely on the effectiveness of the voice recognition system. For the existing and new apps to be truly effective, the built-in voice recognition system needs to be robust (i.e., being able to recognize words spoken in different pitch and tone). The goal of this study is to assess three post-processing classifiers (i.e., bag-of-sentences, support vector machine, …

Confluence Of Density Currents Over An Erodible Bed, Hassan Ismail

Theses and Dissertations

Results from laboratory experiments on conservative density current confluence are reported. Hydraulic characteristics and morphodynamic consequences of the confluence of two continuous release density currents in a horizontal, 45 degree asymmetrical junction are examined and compared to those of terrestrial river junctions. It was observed that density current confluence is markedly different than those in river junctions primarily due to the ease of the dense fluid to convect into the ambient fluid in the junction zone. Upward convection in the junction resulted in low horizontal velocity and shear stresses on the bed of the junction zone, followed by re-plunging to …

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 …

Development Of Computer Simulation Model For Urban Region Using Xp-Swmm In Savannah, Georgia, Matthew Dale Ricks

Theses and Dissertations

The objective of this thesis was to determine if it is possible to create, calibrate, and validate a computer simulation model given a limited amount of measured data. In June 1999, significant flooding was experienced throughout the Casey Canal North drainage basin in Savannah, Georgia. Time-depth rainfall data from a single gage was recorded for this event, along with peak water surface elevations throughout the basin. The computer model chosen for this application was XP-SWMM, which was approved by the Federal Emergency Management Agency to simulate both one dimensional and two dimensional hydraulic models. XP-SWMM was chosen due to its …

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 …

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 …

An Engineering Approach For The Design Of Archaeological Reburial Systems, Angel Ari Perez Mejia

Theses and Dissertations

Archaeological sites are a non-renewable resource which is often our only link to the past. However, sites are under constant threat of destruction due to construction activities. Civil engineers and archaeologists must the work together to ensure both the continued survival of archaeological sites while allowing for development to continue. Reburial systems, when properly designed and constructed, allow for the protection of archaeological sites while allowing the continued use of the land. However, because reburial as an intentional conservation technique is relatively modern, practice is fragmented and there are no universally accepted guidelines. Current reburial system design relies on prescriptive …

Functionalized Graphitic Nanoreinforcement For Cement Composites, Nima Zohhadi

Theses and Dissertations

Physical and mechanical properties of graphitic nanomaterials, in particular multiwalled carbon nanotubes (MWCNTs) and graphene nano-platelets (GNPs) make them promising candidates for nanoreinforcement of cement composites. The two key challenges associated with the incorporation of MWCNTs and GNPs are to attain uniform dispersion and interfacial bonding within the composite matrix. The effects of three main-stream dispersion techniques (namely, ultrasonication, acid-etching, and surfactant-coating) on the mechanical properties and microstructure of MWCNT- and GNP-cement composites were experimentally studied. Compressive strength tests and different characterization techniques including dynamic light scattering, Raman spectroscopy, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, and transmission …

Scheduling Of Container Handling Equipment In Marine Container Terminals, Narges Kaveshgar

Theses and Dissertations

To improve the competitiveness of marine container terminals, it is critical to minimize the makespan of a container vessel. The makespan is defined as the latest completion time among all handling tasks of the container vessel. Lower makespan (i.e. lower vessel turn time) can be achieved through better scheduling of the container handling equipment during vessel operations. The scheduling of terminal equipment is an operational problem, and a detailed schedule for each type of equipment operating in the terminal is necessary. Several studies have applied operations research techniques to optimize the processes of equipment in a terminal. This dissertation investigates …

Context-Sensitive Seismic Strengthening And Repair Of Substandard Confined Masonry, Rahim Ghorbani

Theses and Dissertations

Confined masonry (CM) is a construction system consisting of load-bearing masonry panels that are confined with cast-in-place reinforced concrete tie columns and beams. Due to satisfactory seismic performance, CM has become the predominant low-rise residential construction system in several areas around the world. However, in developing regions, the use of substandard materials, details and construction practices may result in inadequate performance as highlighted in the 2010 earthquakes in Haiti and Chile. In the aftermath of an earthquake, households are often reluctant to reoccupy their dwellings due to concerns about safety of structures. If feasible, preventive (pre-hazard) strengthening or structural repair …