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2014

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Articles 721 - 735 of 735

Full-Text Articles in Civil Engineering

Rapid Repair Of Severely Damaged Rc Columns Under Combined Loading Of Flexure, Shear, And Torsion With Externally Bonded Cfrp, Ruili He Jan 2014

Rapid Repair Of Severely Damaged Rc Columns Under Combined Loading Of Flexure, Shear, And Torsion With Externally Bonded Cfrp, Ruili He

Doctoral Dissertations

"This research aimed to develop a technique to rapidly repair reinforced concrete (RC) bridge columns for emergency service restoration after severe earthquake damage has occurred. Experimental and analytical studies were conducted to study the performance and effectiveness of the proposed repair method. The experimental study included a series of 1/2-scale RC square bridge columns originally tested to failure under constant axial and increasing cyclic lateral loadings resulting in combined flexure, shear, and torsion with different torsional-to-flexural moment ratios. Using externally bonded carbon fiber reinforced polymer (CFRP) sheets, each column was repaired over a 3-day period and then retested under the …

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Plant Uptake Of Environmental Contaminants: Applications In Phytoscreening, Matthew Alan Limmer Jan 2014

Plant Uptake Of Environmental Contaminants: Applications In Phytoscreening, Matthew Alan Limmer

Doctoral Dissertations

"Plants interact directly with their surroundings, extracting nutrients and water from the subsurface to support growth and development of the plant. Through the roots, plants also exude and uptake numerous chemicals. Many of the pathways can also be used by environmental contaminants to be translocated to above ground plant tissues. Such uptake of contaminants has proven useful in remediation and phytoscreening - the use of plants to delineate contaminant plumes. Sampling of trees at contaminated field sites has been used to identify areas of groundwater contaminated with a variety of chlorinated solvents. The use of plants as contaminant biosensors requires …

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Seismic Repair Of Bridge Columns With Interlocking Spirals And Fractured Bars, Yang Yang Jan 2014

Seismic Repair Of Bridge Columns With Interlocking Spirals And Fractured Bars, Yang Yang

Doctoral Dissertations

"During earthquakes, reinforced concrete (RC) bridge columns may experience different levels of damage such as cracking, spalling, or crushing of concrete and yielding, buckling, or fracture of reinforcing bars. This study developed and assessed permanent and emergency methods to repair damaged bridge columns with fractured longitudinal reinforcement through experimental and modeling work. The permanent repair method involved replacement of the plastic hinge region by removal of spirals, replacement of longitudinal bar segments by mechanically splicing with new bars segments attached with mechanical couplers, replacement of concrete, and installation of an externally bonded carbon fiber reinforced polymer (CFRP) jacket. The emergency …

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Longitudinal Analysis Of Crash Frequency Data, Mojtaba Ale Mohammadi Jan 2014

Longitudinal Analysis Of Crash Frequency Data, Mojtaba Ale Mohammadi

Doctoral Dissertations

"This study comprises mainly of three papers. First, a systematic evaluation of the effects of Missouri's Strategic Highway Safety Plan between 2004 and 2007 is presented. Negative binomial regression models were developed for the before-through-change conditions for the various collision types and crash severities. The models were used to predict the expected number of crashes assuming with and without the implementation of MSHSP. This procedure estimated significant reductions of 10% in crashes frequency and a 30% reduction for fatal crashes. Reductions in the number of different collision types were estimated to be 18-37%. The results suggest that the MSHSP was …

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Evaluation Of The Empirical Deck Design For Vehicular Bridges, Georges El-Gharib Jan 2014

Evaluation Of The Empirical Deck Design For Vehicular Bridges, Georges El-Gharib

UNF Graduate Theses and Dissertations

This research evaluated the feasibility of the empirical design method for reinforced concrete bridge decks for the Florida Department of Transportation [FDOT]. There are currently three methods used for deck design: empirical method, traditional method and finite element method. This research investigated and compared the steel reinforcement ratios and the stress developed in the reinforcing steel for the three different methods of deck design. This study included analysis of 15 bridge models that met the FDOT standards. The main beams were designed and load rated using commercial software to obtain live load deflections. The bridges were checked to verify that …

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Examining Optimal Form Of Two Scale Approximation (Tsa) For Calculating Snl Source Term, Dorukhan Ardag Jan 2014

Examining Optimal Form Of Two Scale Approximation (Tsa) For Calculating Snl Source Term, Dorukhan Ardag

UNF Graduate Theses and Dissertations

Nonlinear four-wave interactions (Snl) are critical for acquiring realistic spectra needed by operational wave models. High computational demand to calculate these interactions led to an approximation method named the Discrete Interaction Approximation (DIA) to be used broadly in the major operational wave models for a long time. However, the accuracy of the DIA has been controversial since it was first introduced and more precise approximations such as the Two Scale Approximation (TSA in short) are now available. The only issue with the initial TSA`s efficiency is performing an order of a magnitude slower than the DIA in speed. …

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Analysis Of A 10-Year Nearshore Wave Database And Its Implications To Littoral Processes, Luis Humberto Montoya Jan 2014

Analysis Of A 10-Year Nearshore Wave Database And Its Implications To Littoral Processes, Luis Humberto Montoya

UNF Graduate Theses and Dissertations

The variability of the nearshore wave climate is investigated via the analysis of over 10 years of Acoustic Doppler Current Profiler (ADCP) data from a gauge deployed at Melbourne Beach, FL. Examples of large yearly variability in the significant wave height, peak period, mean direction and energy distribution are found in the data. Estimates of the averaged spectra for the entire record show that the average wave energy is distributed almost symmetrically with the peak being close to shore-normal. It was expected that the peak would be shifted towards the north of shore-normal considering net north to south longshore sediment …

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Factors Affecting Storm Characteristics In The Battery And Vicinity, Shannon A. Kay Jan 2014

Factors Affecting Storm Characteristics In The Battery And Vicinity, Shannon A. Kay

UNF Graduate Theses and Dissertations

Tropical cyclones (TCs) Irene and Sandy caused major damages in back to back years to the most densely populated city in the United States stunning the residents with storms linked to seemingly impossible probabilities. Such activity has raised questions about the effect of non-stationary aspects within atmospheric circulation on storm behavior and some assumptions inherent in previous hazard studies of the New York City (NYC) area. This study analyzes statistical aspects of hazard quantification for this area related to this non-stationarity and statistical characterization. In particular this study investigates the presence of multiple populations of storms, it also tests current …

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Dynamic Testing Procedures For Performance Assessment Of Nuclear Fuel Rods, Travis M. Adams Jan 2014

Dynamic Testing Procedures For Performance Assessment Of Nuclear Fuel Rods, Travis M. Adams

Honors Theses and Capstones

Existing transportation probabilistic risk assessment for spent nuclear fuel in the United States is based on short-term (decades) on-site storage at power plants before transport. Updated risk assessment estimates will be required as extended on-site storage (centuries) and higher burnup levels in fuel become standard. Nuclear fuel rods under these two conditions are more brittle than rods from short-term storage and intermediate burnup due to several mechanisms, including hydrogen embrittlement. Development of risk assessment requires characterizations of dynamic behavior of these degraded rods under transportation scenarios. This Honors thesis provides an initial literature review for a larger project that will …

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Bridge Deck Condition Assessment Using Destructive And Nondestructive Methods, Brandon Tyler Goodwin Jan 2014

Bridge Deck Condition Assessment Using Destructive And Nondestructive Methods, Brandon Tyler Goodwin

Masters Theses

"This study investigates two bridge decks in the state of Missouri using both nondestructive and destructive testing methods. The Missouri Department of Transportation (MoDOT) is responsible for the monitoring and maintenance of over 10,000 bridges. Currently monitoring of these bridges includes a comprehensive visual inspection. In this study, ground-coupled ground penetrating radar (GPR) is used to estimate deterioration, along with other traditional methods, including visual inspection, and core evaluation. Extracted core samples were carefully examined, and the volume of permeable pore space was determined for each core. After the initial investigation, the two bridges underwent rehabilitation using hydrodemolition as a …

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Comparison Of Costs Of Personal Protective Equipment For All Workers To Avoid Costs Of Fall Accidents, Sultan Noori Al-Karawi Jan 2014

Comparison Of Costs Of Personal Protective Equipment For All Workers To Avoid Costs Of Fall Accidents, Sultan Noori Al-Karawi

Masters Theses

"The construction industry is one of the most important industries in the United States. It is the biggest contributor in the growth of the U.S. economy. Despite the great achievements and prominent role for this sector in the U.S. economy, the construction industry is suffering from neglect and dereliction by related government institutions and private companies. This neglect led to formation of a negative image about the construction industry that has caused a deep impact in productivity and economic growth. One of the reasons is a high percentage of accidents that occur within the construction industry which leads to injuries …

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Bond Performance Of Recycled Aggregate Concrete, Amanda Renee Steele Jan 2014

Bond Performance Of Recycled Aggregate Concrete, Amanda Renee Steele

Masters Theses

"In recent decades, engineers have sought a more sustainable method to dispose of concrete construction and demolition waste. One solution is to crush this waste concrete into a usable gradation for new concrete mixes. This not only reduces the amount of waste entering landfills but also alleviates the burden on existing sources of quality natural concrete aggregates. The objective of this study was to determine to effect of replacing coarse natural aggregates for recycled concrete aggregates (RCA) on the bond strength between deformed mild reinforcing steel and surrounding concrete. Two different RCA replacement levels were considered, 50% and 100%, and …

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Shear Behavior Of High Strength Self-Consolidating Concrete In Nu Bridge Girders, Alexander Michael Griffin Jan 2014

Shear Behavior Of High Strength Self-Consolidating Concrete In Nu Bridge Girders, Alexander Michael Griffin

Masters Theses

"As the nation's infrastructure continues to age, advanced concrete technologies have been developed to both reduce a structure's costs and increase its life expectancy. Since the early 1990's, self-consolidating concrete (SCC) has been one of these technologies. Many, however, have been reluctant to implement SCC in highway girders due to the mixture constituents. One of these concerns is the reduced content and size of the coarse aggregate. These differences in the concrete potentially hinder SCC's mechanical properties and shear resistance. Additionally, for high strength concretes (HSC) with weaker aggregates, shear cracks tend to propagate through the coarse aggregate, reducing the …

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Polyurethane Foam Infill For Fiber Reinforced Polymer (Frp) Bridge Deck Panels: An Evaluation Of Core Alternatives Using Small Scale Experimental Testing, Matthew Scott Hopkins Jan 2014

Polyurethane Foam Infill For Fiber Reinforced Polymer (Frp) Bridge Deck Panels: An Evaluation Of Core Alternatives Using Small Scale Experimental Testing, Matthew Scott Hopkins

Masters Theses

"Fiber reinforced polymer (FRP) decking is a concept that has been explored in recent decades as one solution to the performance issues of conventional concrete bridge decking. Many sandwich panel designs made of glass reinforced polyester or vinyl ester resin have been well developed, and manufactured using filament winding, hand lay-up, and extrusion methods. The major benefits of these panels was their light weight, corrosion resistance, fatigue performance, and potential for rapid field assembly. However, high initial costs coupled with small state budgets have kept them from main stream adoption. A viable alternative, is a foam/reinforced foam core sandwich panel …

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Measurements And Transient Multistep Outflow Simulation Of Soil-Water Characteristic Curve For Soils Modified With Biopolymers, Xiaoyi Zhao Jan 2014

Measurements And Transient Multistep Outflow Simulation Of Soil-Water Characteristic Curve For Soils Modified With Biopolymers, Xiaoyi Zhao

Masters Theses

"In recent decades, biopolymers have shown promising applications in soil modification due to its environmental friendly nature. Most of the studies, however, focused on mechanical properties at saturated or unsaturated conditions. The study on unsaturated soil behaviors under controlled pore air and pore water pressures were limited. Soil-water characteristic curve (SWCC), relating water content with matric suction is a key property to evaluate unsaturated soils. With SWCC, other soil properties, such as hydraulic conductivity and shear strength can be estimated. In this study, SWCC of sands modified with different biopolymers were measured with both Tempe cell and Fredlund SWCC device. …

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