Civil Engineering Commons^™

Dynamic Modeling Approach To Quantify Change Orders Impact On Labor Productivity, Zain Al-Kofahi

Electronic Theses and Dissertations

In construction projects, change orders are commonly faced. These change orders, which are issued by the owner, may cause interruption to the contractor's work, resulting in damages such as loss of labor productivity, delay damages, and cost overruns which may lead to claims. The relationship between change orders and loss of labor productivity is not well understood because of the difficulty in linking the cause of the productivity loss to the change order. So, to receive compensation, the contractor needs to prove with a credible calculation that the productivity loss was a result of the change order issued by the …

Triclocarban Influences Antibiotic Resistance And Alters Anaerobic Digester Microbial Community Structure, Daniel Elliott Carey, Daniel Zitomer, Krassimira R. Hristova, Anthony D. Kappell, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Triclocarban (TCC) is one of the most abundant organic micropollutants detected in biosolids. Lab-scale anaerobic digesters were amended with TCC at concentrations ranging from the background concentration of seed biosolids (30 mg/kg) to toxic concentrations of 850 mg/kg to determine the effect on methane production, relative abundance of antibiotic resistance genes, and microbial community structure. Additionally, the TCC addition rate was varied to determine the impacts of acclimation time. At environmentally relevant TCC concentrations (max detect = 440 mg/kg), digesters maintained function. Digesters receiving 450 mg/kg of TCC maintained function under gradual TCC addition, but volatile fatty acid concentrations increased, …

Triclosan Adsorption Using Wastewater Biosolids-Derived Biochar, Yiran Tong, Brooke K. Mayer, Patrick J. Mcnamara

Civil and Environmental Engineering Faculty Research and Publications

Organic micropollutants are ubiquitous in the environment and stem from municipal wastewater treatment plant discharges. Adsorption can be used as a tertiary treatment to complement the conventional activated sludge process to remove micropollutants prior to discharge. This research evaluated the performance of wastewater biosolids-derived biochar as an adsorbent to remove triclosan from water. Pre-conditioning of the biochar using hydrochloric acid (HCl) was an essential step for triclosan adsorption. Using acid-conditioned biochar, maximum adsorption of 872 μg triclosan per g biochar was achieved with biochar produced at 800 °C. Biochar produced at higher pyrolysis temperatures tended to have higher triclosan sorption …

Probability-Based Hurricane Resilience Evaluation And Retrofitting For Residential Community, Yadong Dong

Dissertations, Master's Theses and Master's Reports

Wood residential construction is vulnerable to hurricanes, as evident in recent hurricane events. Many studies indicated that the changing climate may very likely alter hurricane patterns, which could lead to more severe hurricane damage to the wood residential construction that accounts for 90% of the residence in the USA. On the other hand, deterioration of material increases the chance of structural failure by reducing the structural capacity (e.g., corrosion of fasteners in roof panel could significantly reduce the withdrawal capacity of the roofing structure during hurricane events).

Currently, most hurricane damage estimations only focus on direct loss (e.g., structural loss). …

Computer Vision Based Structural Identification Framework For Bridge Health Mornitoring, Tung Khuc

Electronic Theses and Dissertations

The objective of this dissertation is to develop a comprehensive Structural Identification (St-Id) framework with damage for bridge type structures by using cameras and computer vision technologies. The traditional St-Id frameworks rely on using conventional sensors. In this study, the collected input and output data employed in the St-Id system are acquired by series of vision-based measurements. The following novelties are proposed, developed and demonstrated in this project: a) vehicle load (input) modeling using computer vision, b) bridge response (output) using full non-contact approach using video/image processing, c) image-based structural identification using input-output measurements and new damage indicators. The input …

Microwave Material Characterization Of Alkali-Silica Reaction (Asr) Gel In Cementitious Materials, Ashkan Hashemi

Doctoral Dissertations

"Since alkali-silica reaction (ASR) was recognized as a durability challenge in cement-based materials over 70 years ago, numerous methods have been utilized to prevent, detect, and mitigate this issue. However, quantifying the amount of produced ASR byproducts (i.e., ASR gel) in-service is still of great interest in the infrastructure industry. The overarching objective of this dissertation is to bring a new understanding to the fundamentals of ASR formation from a microwave dielectric property characterization point-of-view, and more importantly, to investigate the potential for devising a microwave nondestructive testing approach for ASR gel detection and evaluation. To this end, a comprehensive …

Geotechnical State-Of-The-Art In Guatemala -- Ground Stabilization, Fernando Rafael Callejas Benitez

Doctoral Dissertations

"History provides an understanding of the present and in a way, a guide for the future. The state-of-the-art is often referred to as a snapshot of the most significant works and contributions made in a field of study; In this case the focus is on Guatemalan geotechnical engineering. This study presents a comprehensive description of the different events that impulse geotechnical engineering in Guatemala.

As part of the description of the state-of-the-practice an investigation of the different human (engineers/contractors) and physical resources (laboratories/field equipment) and their capabilities are presented. An overview of the civil engineering programs is presented. Then, the …

Static And Dynamic Characterization Of Tied Arch Bridges, John Edward Finke

Doctoral Dissertations

"Tied arch bridges have been designed and constructed since the late 19th century. With their open vista owing to minimalist features tied arch bridges continue to appeal the public. Tied arch bridges are both aesthetic and economical alternates to long span bridges holding a place in the hierarchy of major bridges. They fit in a niche between viable and economical plate girder spans and short cable stayed bridge spans. There are several variations of the tied arch with the most common form being those having vertical hangers, stiff tie girders and slender arch ribs. This tied arch variation is examined …

Composite Confinement Systems For Rc Column Repair And Construction Under Seismic Loads: Concept, Characterization And Performance, Mostafa Fakharifar

Doctoral Dissertations

"This study aims at developing, characterizing and validating an integrated composite confinement system of conventional jackets for: (1) repair and retrofit of existing bridge columns; and (2) construction of new bridge columns, subjected to earthquake excitations.

A new composite steel confinement jacket was proposed by combining a thin steel sheet and prestressing strands as a hybrid jacket, incorporating active and passive confining pressure on damaged RC columns. Both experimental and analytical studies were conducted to understand the performance and effectiveness of the proposed repair method. The experimental study involved two 1/2-scale lap-spliced deficient RC bridge columns originally tested to failure …

Rehabilitation And Strengthening Of Reinforced Concrete Members Using A Fiber Reinforced Cementitious Matrix Composite, Zena Riyadh Aljazaeri

Doctoral Dissertations

“Externally bonded fiber reinforced cementitious matrix (FRCM) for structural members was tested and evaluated as a new class of composite material for repairing and strengthening infrastructures. In comparison with fiber reinforced polymer (FRP) composites, FRCM composite has a superior high temperature resistance and great compatibility with concrete substrates. Experimental investigation is ongoing in the United States to evaluate the structural and durability performance of FRCM composite to be implemented in field applications. This experimental program consisted of testing 12 strengthened reinforced concrete (RC) beams to study the fatigue and flexure performance under environmental exposure and sustained stress, 10 strengthened RC …

Innovative Techniques For Seismic-Resistant Bridge Columns Under Ground Motion Excitations, Ayman A. Moustafa

Doctoral Dissertations

“This dissertation provides innovative alternative solutions for replacing conventional reinforced concrete columns. The proposed columns displayed enhanced seismic resistance and properties compared to their counterpart conventional columns. Two main techniques were followed and proposed to develop seismic-resistant columns. The first technique utilized rubberized concrete to internally enhance energy dissipation and damping. Materials testing of rubberized concrete with scrap tire replacement of fine aggregates were performed to evaluate its dynamic properties. Shaking table testing of a rubberized concrete column was performed and the behavior was compared to that of the conventional one. The rubberized column showed an increase of 16% in …

Safety Implications Of Transit Operator Schedule Policies, Hung Hoang

UNF Graduate Theses and Dissertations

In the bus transit community, driving long hours or spending extra hours at work are very common. This is true in the State of Florida, where bus transit is a very popular mode of public transportation. Although the correlation between a bus driver’s schedule and a crash event appears intuitive, further study regarding the effects of operator driving schedules on accident rates is needed to evaluate safety measures. The focus of this research is on the examination of bus driver schedules, and the effects of scheduling on accident rates in Florida. Data were collected at five bus transit agencies including …

Analysis Of A Long-Term Record Of Nearshore Currents And Implications In Littoral Transport Processes, Carolina Burnette

UNF Graduate Theses and Dissertations

A seasonal and long-term analysis of the vertical structure of currents in the nearshore is conducted to determine the role of the wind in driving currents and consequently affecting littoral transport processes. Approximately ten years (January, 2002 – October, 2011) of nearshore current profiles are examined using the data collected with an Acoustic Doppler Current Profiler (ADCP) installed off of Spessard Holland North Beach Park located in Melbourne Beach, Florida. Additionally, wind data collected with a directional anemometer from September, 2002, until October, 2008, are used to further characterize the long-term hydrodynamic forcing. With the shoreline oriented nominally 17^{o …}

The Influence Of Sea-Level Rise On Salinity In The Lower St. Johns River And The Associated Physics, Teddy Mulamba

UNF Graduate Theses and Dissertations

The lower St Johns River is a low-gradient coastal river with tidal hydrodynamics that remain active from the Atlantic Ocean through to the upstream end of Lake George (river km 200). Salinity in the lower St Johns River is spatially and temporally variable, whereby the salinity distribution is driven primarily by the combination of ocean processes of tides and storm surges and hydrological processes of watershed runoff. This study examines the probability distributions and modes of behavior of salinity for present-day conditions using data, numerical modeling and eigen-analysis. The hypothesis is that long-term changes (decadal scale) in the ocean processes …

Potential Wave Impacts On Shorelines In Intertidal Waterways, Collin Ries

UNF Graduate Theses and Dissertations

Coastal erosion is caused by a deficit in the sediment balance along coastal shorelines. Within the intertidal waterway of Jacksonville, Florida, the primary processes acting on the shoreline are tidal currents and waves generated by winds and passing vessels. This study focuses on the analysis of vessel-generated waves and their possible effects on different shoreline types. The experiment conducted herein examines variations in turbidity related to passing boats at a specifically selected site location, at which different tidal stages expose three different shoreline types, a non-vegetated scarp, a vegetated scarp and a vegetated area with no scarp in the breaking …

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 …

Java Computer Animation For Effective Learning Of The Cholesky Algorithm With Transportation Engineering Applications, Ivan Makohon, Duc T. Nguyen, Mecit Cetin

Civil & Environmental Engineering Faculty Publications

In this paper, the well-known Cholesky Algorithm (for solving simultaneous linear equations, or SLE) is re-visited, with the ultimate goal of developing a simple, user-friendly, attractive, and useful Java Visualization and Animation Graphical User Inter-face (GUI) software as an additional teaching tool for students to learn the Cholesky factorization in a step-by-step fashion with computer voice and animation. A demo video of the Cholesky Decomposition (or factorization) animation and result can be viewed online from the website: http://www.lions.odu.edu/~imako001/cholesky/demo/index.html. The software tool developed from this work can be used for both students and their instructors not only to master this technical …

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 …