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Articles 2011 - 2040 of 7869

Full-Text Articles in Civil and Environmental Engineering

Flexural And Shear Behavior Of Reinforced Concrete Members Strengthened With A Discrete Fiber-Reinforced Polyurea System, Courtney E. Greene, John J. Myers Feb 2013

Flexural And Shear Behavior Of Reinforced Concrete Members Strengthened With A Discrete Fiber-Reinforced Polyurea System, Courtney E. Greene, John J. Myers

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Recent research has been conducted to evaluate the benefits provided by externally applied discrete fiber-reinforced polyurea (DFRP) coating systems. This coating was proposed to allow for ease of construction in repair-retrofit situations and to provide multihazard benefits, ranging from blast or impact fragmentation mitigation to seismic reinforcement and general strengthening. This phase of research investigated the flexural and shear reinforcement capabilities of the systems. Testing parameters included type of structural failure, polyurea, and fiber volume fraction. Additionally, the effects of the thickness of the composite system were considered. Concrete beam specimens were fabricated and coated per the designed test matrix …

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Pore Geometry Effects On Intrapore Viscous To Inertial Flows And On Effective Hydraulic Parameters, Kuldeep Chaudhary, M. Bayani Cardenas, Wen Deng, Philip C. Bennett Feb 2013

Pore Geometry Effects On Intrapore Viscous To Inertial Flows And On Effective Hydraulic Parameters, Kuldeep Chaudhary, M. Bayani Cardenas, Wen Deng, Philip C. Bennett

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this article, the effects of different diverging-converging pore geometries were investigated, and the microscale fluid flow and effective hydraulic properties from these pores were compared with that of a pipe from viscous to inertial laminar flow regimes. The flow fields are obtained using computational fluid dynamics, and the comparative analysis is based on a new dimensionless hydraulic shape factor β, which is the "specific surface" scaled by the length of pores. Results from all diverging-converging pores show an inverse pattern in velocity and vorticity distributions relative to the pipe flow. The hydraulic conductivity K of all pores is …

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Molecular Diversity Of Bacteroidales In Fecal And Environmental Samples And Swine-Associated Subpopulations, Regina Lamendella, Kent C. Li, Daniel B. Oerther, Jorge W. Santo Domingo Feb 2013

Molecular Diversity Of Bacteroidales In Fecal And Environmental Samples And Swine-Associated Subpopulations, Regina Lamendella, Kent C. Li, Daniel B. Oerther, Jorge W. Santo Domingo

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Several swine-specific microbial source tracking methods are based on PCR assays targeting Bacteroidales 16S rRNA gene sequences. The limited application of these assays can be explained by the poor understanding of their molecular diversity in fecal sources and environmental waters. In order to address this, we studied the diversity of 9,340 partial (>600bp in length) Bacteroidales 16S rRNA gene sequences from 13 fecal sources and nine feces-contaminated watersheds. The compositions of major Bacteroidales populations were analyzed to determine which host and environmental sequences were contributing to each group. This information allowed us to identify populations which were both exclusive …

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The Bridge Newsletter Spring 2013, Missouri University Of Science And Technology Feb 2013

The Bridge Newsletter Spring 2013, Missouri University Of Science And Technology

The Bridge Newsletter

-Bringing unique research capabilities to campus
-From trash into treasure
-Improving wellness
-Raising the roof

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A Novel Approach To Detecting Breathing-Fatigue Cracks Based On Dynamic Characteristics, Guirong Yan, Alessandro De Stefano, Emiliano Matta, Ruoqiang Feng Jan 2013

A Novel Approach To Detecting Breathing-Fatigue Cracks Based On Dynamic Characteristics, Guirong Yan, Alessandro De Stefano, Emiliano Matta, Ruoqiang Feng

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

During the Service Life of Structures, Breathing-Fatigue Cracks May Occur in Structural Members Due to Dynamic Loadings Acting on Them. These Fatigue Cracks, If Undetected, Might Lead to a Catastrophic Failure of the Whole Structural System. Although a Number of Approaches Have Been Proposed to Detect Breathing-Fatigue Cracks, Some of Them Appear Rather Sophisticated or Expensive (Requiring Complicated Equipment), and Others Suffer from a Lack of Sensitivity. in This Study, a Simple and Efficient Approach to Detecting Breathing-Fatigue Cracks is Developed based on Dynamic Characteristics of Breathing Cracks. First, Considering that Breathing Cracks Introduce Bilinearity into Structures, a Simple System …

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A Comparative Study Of The Bond Strength Of Reinforcing Steel In High-Volume Fly Ash Concrete And Conventional Concrete, Mahdi Arezoumandi, Michael H. Wolfe, Jeffery S. Volz Jan 2013

A Comparative Study Of The Bond Strength Of Reinforcing Steel In High-Volume Fly Ash Concrete And Conventional Concrete, Mahdi Arezoumandi, Michael H. Wolfe, Jeffery S. Volz

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The production of Portland cement-the key ingredient in concrete-generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete's contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. An experimental investigation was conducted to compare the bond strength of reinforcing steel in high-volume fly ash concrete (HVFAC)-concrete with at least 50% of the cement replaced with fly ash-with conventional concrete (CC). This experimental program consisted of 12 pull-out …

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Intermittency And Local Dissipation Scales Under Strong Mean Shear, Khandakar Niaz Morshed, Subhas Karan Venayagamoorthy, Lakshmi Prasad Dasi Jan 2013

Intermittency And Local Dissipation Scales Under Strong Mean Shear, Khandakar Niaz Morshed, Subhas Karan Venayagamoorthy, Lakshmi Prasad Dasi

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

We experimentally probe the local dissipation scale distribution Q(η) and temporal fluctuations of the turbulent kinetic energy dissipation rate ε in the strongly anisotropic flow past a backward facing step. A shift in Q(η) and corresponding reduction in the relative intermittency of ε is observed with increasing mean shear S. We offer physical arguments to elucidate the role of strong shear on the small-scale structure. A local mean-shear dissipation Reynolds number, ReS ≡ {ε}/(S2ν), is proposed that may define a family of universal small-scale structures of turbulence. © 2013 American Institute of Physics.

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Extension Of The Reiner-Riwlin Equation To Determine Modified Bingham Parameters Measured In Coaxial Cylinders Rheometers, Dimitri Feys, Jon E. Wallevik, Ammar Yahia, Kamal H. Khayat, Olafur H. Wallevik Jan 2013

Extension Of The Reiner-Riwlin Equation To Determine Modified Bingham Parameters Measured In Coaxial Cylinders Rheometers, Dimitri Feys, Jon E. Wallevik, Ammar Yahia, Kamal H. Khayat, Olafur H. Wallevik

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Determination of the Exact Rheological Properties, in Fundamental Units, of Cementitious Materials Has Become Gradually a Necessary Step in the Domain of Concrete Science. Several Types of Rheometers and their Corresponding Transformation Equations Are Described in the Literature. in This Paper, the Reiner-Riwlin Transformation Equation, Valid for Coaxial Cylinders Rheometers, is Developed for the Modified Bingham Model, which is an Extension of the Bingham Model with a Second Order Term in the Shear Rate. the Established Transformation is Shown to Be Compatible with the Reiner-Riwlin Equation for the Bingham and Herschel-Bulkley Models. its Validation is Further Proven by Means …

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Effect Of High-Volume Fly Ash On Shear Strength Of Concrete Beams, Mahdi Arezoumandi, Jeffery Volz, John Myers Jan 2013

Effect Of High-Volume Fly Ash On Shear Strength Of Concrete Beams, Mahdi Arezoumandi, Jeffery Volz, John Myers

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Every year concrete production exceeds 6.5 billion tons worldwide, nearly 1 ton for every man, woman, and child on the planet. In fact, concrete is used 10 times more than any other building material in the world, primarily because of its incredible versatility, availability, and relatively low cost. Unfortunately, the production of Portland cement - the key ingredient in concrete - generates approximately a pound of carbon dioxide for every pound of cement produced. One method of reducing concrete's carbon footprint is to replace a significant amount of the cement with fly ash, a by-product of coal-burning thermal power stations. …

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Effect Of Moist Curing And Use Of Lightweight Sand On Characteristics Of High-Performance Concrete, Soo Duck Hwang, Kamal H. Khayat, Dalia Youssef Jan 2013

Effect Of Moist Curing And Use Of Lightweight Sand On Characteristics Of High-Performance Concrete, Soo Duck Hwang, Kamal H. Khayat, Dalia Youssef

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Factorial design approach was undertaken to determine the effect of initial moist-curing duration (0 and 6 days) on properties of high-performance concrete (HPC) made with different water-to-cementitious materials ratios (w/cm) of 0.30 and 0.40 and sand substitution rates with lightweight sand (LWS) of 0 and 30 %, by volume. Mechanical properties of HPC are shown to be mainly affected by w/cm and total shrinkage of concrete by the LWS replacement rate and initial moist-curing period. It should be noted that concrete made with 30 % LWS replacement that did not receive any moist-curing exhibited lower shrinkage than moist-cured concrete prepared …

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Aggregate Shape Characterization Using Digital Image Processing, Norbert H. Maerz, David Newton Richardson Jan 2013

Aggregate Shape Characterization Using Digital Image Processing, Norbert H. Maerz, David Newton Richardson

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Aggregates must meet certain specifications to be acceptable in asphalt and concrete applications. Among these are specifications that deal with the various aspects of aggregate shape, including flatness and elongation and aggregate angularity. The current practice for ensuring those specifications is the use of manual-mechanical tests. These tests are time consuming, labor intensive and subjective. In addition, tests such as the compacted or uncompacted voids tests (Figure 1), are taken to be a shape (angularity) indicator, even thought the measured quantify is the void ratio. This report describes a prototype of an automated digital video image analysis system that measures …

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Effect Of Crumb Rubber Modifier Dissolution On Storage Stability Of Crumb Rubber-Modified Asphalt, Amir Ghavibazoo, Magdy Abdelrahman, Mohyeldin Ragab Jan 2013

Effect Of Crumb Rubber Modifier Dissolution On Storage Stability Of Crumb Rubber-Modified Asphalt, Amir Ghavibazoo, Magdy Abdelrahman, Mohyeldin Ragab

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Crumb rubber-modified asphalt (CRMA) extensively suffers from high-temperature storage instability. Because of the higher density of the crumb rubber modifier (CRM) particles, they settle down to the bottom of storage tanks and cause variation between physical properties of the top and bottom samples. The storage stability of the CRMA changes under different interaction parameters and consequently different mechanisms of interaction. In this research the mechanism of separation under different levels of CRM dissolution was investigated by using Stokes' law. The extent and mechanism of CRM dissolution in asphalt was controlled through regulating interaction temperature and interaction mixing speed. A standard …

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Use Of Vacuum For The Stabilization Of Dry Sand Slopes, B. Bate, Limin Zhang Jan 2013

Use Of Vacuum For The Stabilization Of Dry Sand Slopes, B. Bate, Limin Zhang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Vacuum is proposed as a means for rescuing soil slopes showing signs of impending failure. Two aspects associated with the proposed method were studied: namely, the theory of airflow through dry soils and the effectiveness of vacuum for enhancing the stability of soil slopes. A model test device was developed, and two series of tests were carried out using this device. One was a series of tests on pore-air pressure distributions in dry sand slopes, and the second series involved dry sand slope stability tests. The results revealed that a vacuum (negative pore-air pressure) even as small as 20.4 kPa …

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Spacecraft Module Hole Size And Crack Length Prediction Following A Penetrating Debris Particle Impact, Joel E. Williamsen, William P. Schonberg, Hilary J. Evans Jan 2013

Spacecraft Module Hole Size And Crack Length Prediction Following A Penetrating Debris Particle Impact, Joel E. Williamsen, William P. Schonberg, Hilary J. Evans

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The process used to calculate and reduce the consequences of meteoroid and orbital debris (MOD) penetrations and their link to catastrophic failure has evolved over time. As the threat of the orbital debris population increased in the 1980s and early 1990s, NASA developed a tool to determine the probability of no catastrophic failure, or PNCF, for the space station and to assess possible changes in station design and/or operations to improve that survivability percentage. PNCF is directly related to the PNP, or probability of no penetration, as calculated by Bumper, the code used by NASA to perform MOD risk assessments. …

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Effect Of Fly Ash On The Shear Strength Of Concrete Beams Without Shear Reinforcement, Mahdi Arezoumandi, Jeffery S. Volz, Carlos A. Ortega Jan 2013

Effect Of Fly Ash On The Shear Strength Of Concrete Beams Without Shear Reinforcement, Mahdi Arezoumandi, Jeffery S. Volz, Carlos A. Ortega

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The following paper presents the results of an experimental investigation of the shear strength of full-scale reinforced concrete beams constructed with both high-volume fly ash concrete (HVFAC)-concrete with at least 50% of the cement replaced with fly ash-and conventional concrete (CC). This study includes two HVFAC mixes and one CC mix. The two HVFAC mixes are identical except for the amount of Class C fly ash replacement of cement, with one mix replacing 50% of the cement with fly ash and the other replacing 70 %. The test matrix included 18 beams-six for each concrete type-with three different longitudinal reinforcement …

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Hypervelocity Impact Testing Of Multiwall Targets Using Multiple Simultaneously Launched Projectiles, William P. Schonberg, Steve Evans, Michael D. Bjorkman Jan 2013

Hypervelocity Impact Testing Of Multiwall Targets Using Multiple Simultaneously Launched Projectiles, William P. Schonberg, Steve Evans, Michael D. Bjorkman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Multiwall shield designs for spacecraft have been studied extensively in the last four decades as a means of reducing the perforation threat of the near-Earth particulate environment over equivalent single-wall structures. The performance of an impact shield is typically characterized by its ballistic limit equation, which is obtained through high-speed impact tests that typically use spherical projectiles fired in light gas guns. Traditional firings employ only one projectile per launch package. However, some facilities have taken to launching multiple projectiles of different sizes in a single launch package. In light of the significant role played by a ballistic limit equation …

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Plants As Bio-Indicators Of Subsurface Conditions: Impact Of Groundwater Level On Btex Concentrations In Trees, Jordan Wilson, Rachel Bartz, Matt Limmer, Joel Gerard Burken Jan 2013

Plants As Bio-Indicators Of Subsurface Conditions: Impact Of Groundwater Level On Btex Concentrations In Trees, Jordan Wilson, Rachel Bartz, Matt Limmer, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Numerous Studies Have Demonstrated Trees' Ability to Extract and Translocate Moderately Hydrophobic Contaminants, and Sampling Trees for Compounds Such as BTEX Can Help Delineate Plumes in the Field. However, When BTEX is Detected in the Groundwater, Detection in Nearby Trees is Not as Reliable an Indicator of Subsurface Contamination as Other Compounds Such as Chlorinated Solvents. Aerobic Rhizospheric and Bulk Soil Degradation is a Potential Explanation for the Observed Variability of BTEX in Trees as Compared to Groundwater Concentrations. the Goal of This Study Was to Determine the Effect of Groundwater Level on BTEX Concentrations in Tree Tissue. the Central …

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Modeling Of The Resilient Modulus For Recycled Asphalt Pavement Applications In Base Course Layers, Ehab Noureldin, Magdy Abdelrahman Jan 2013

Modeling Of The Resilient Modulus For Recycled Asphalt Pavement Applications In Base Course Layers, Ehab Noureldin, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The resilient modulus (MR) is an important parameter for the base course layer in the pavement design process. Use of recycled asphalt pavement (RAP) for this layer must take into consideration the effect of various factors that may occur in the field on the MR. Previous numerical models used for the granular base layer could be used for the RAP. The study reported here examined the suitability of RAP procedures under the effect of different factors (e.g., water content, dry density, freeze-thaw cycles). Various percentages of the RAP (50%, 75%, and 100% by weight) were employed …

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Some Insights For The Prediction Of Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy Jan 2013

Some Insights For The Prediction Of Near-Wall Turbulence, Farid Karimpour, Subhas K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, we revisit the eddy viscosity formulation to highlight a number of important issues that have direct implications for the prediction of near-wall turbulence. For steady wall-bounded turbulent flows, we make the equilibrium assumption between rates of production (P) and dissipation (ε) of turbulent kinetic energy (κ) in the near-wall region to propose that the eddy viscosity should be given by vt ε/S2, where S is the mean shear rate. We then argue that the appropriate velocity scale is given by (STL)-1/2 k1/2 where TL = k ε is the turbulence (decay) time scale. The …

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Performance-Based Seismic Design Of Unbonded Precast Post-Tensioned Concrete Filled Gfrp Tube Piers, Haitham M. Dawood, Mohamed Elgawady Jan 2013

Performance-Based Seismic Design Of Unbonded Precast Post-Tensioned Concrete Filled Gfrp Tube Piers, Haitham M. Dawood, Mohamed Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents a seismic design procedure for self-centering precast post-tensioned bridge piers. The piers presented in this manuscript consisted of concrete filled fiber reinforced polymer (FRP) tubes. A large set of 84 piers with different design parameters were analyzed using finite element models. The backbone curve of each pier was developed and bilinearized. The idealized backbone curves were used to develop a set of empirical equations that were able to reproduce the bilinearized backbone curve of a given pier. Different performance criteria have been proposed for the system according to the intensity and the frequency of occurrence of a …

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An Experimental Study On Shear Strength Of Chemically-Based Self-Consolidating Concrete, Mahdi Arezoumandi, Jeffery S. Volz Jan 2013

An Experimental Study On Shear Strength Of Chemically-Based Self-Consolidating Concrete, Mahdi Arezoumandi, Jeffery S. Volz

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

An experimental investigation was conducted to compare the shear strength of full-scale beams constructed with chemically based, self-consolidating concrete (SCC) with conventional concrete (CC). This experimental program consisted of 16 rectangular beams (12 without shear reinforcing and 4 with shear reinforcing in the form of stirrups), 8 beams for each mix design. Additionally, three different longitudinal reinforcement ratios were evaluated within the test matrix. The beam specimens were tested under a simply supported four-point condition. The experimental shear strengths of the beams were compared with both the shear provisions of selected standards (U.S., Australia, Canada, Europe, and Japan) and a …

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Effect Of Fly Ash On Growth Of Mustard And Corn, Cailie Carlile, Snehalata Nadiger, Joel Gerard Burken Jan 2013

Effect Of Fly Ash On Growth Of Mustard And Corn, Cailie Carlile, Snehalata Nadiger, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Fly Ash is Generated as a By-Product of Coal Combustion and Contains Many Nutrients, Such as Ca, K, Na, Mg, and S, as Well as Toxic Metals Such as As, B, Cd, Cr, Hg, and Pb. for This Project, the Goal is to Optimize a Phytoremediation Technique to Stabilize the Toxic Metals and Produce Biomass Which Could Have Benefit for Example as Biofuel. the Hypothesis Was that Different Amendments Would Improve the Water Holding Properties of the Ash and Reduce Metals Availability and Toxicity. Flyash Was Combined with Leaf Mulch (1%, 3%, 5%, 10%, 20%), Wood Mulch (1%, 3%, 5%, …

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Hydro-Nexrad-2: Real-Time Access To Customized Radar-Rainfall For Hydrologic Applications, Witold F. Krajewski, Anton Kruger, Satpreet Singh, Bong Chul Seo, James A. Smith Jan 2013

Hydro-Nexrad-2: Real-Time Access To Customized Radar-Rainfall For Hydrologic Applications, Witold F. Krajewski, Anton Kruger, Satpreet Singh, Bong Chul Seo, James A. Smith

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Hydro-NEXRAD-2 (HNX2) is a prototype system that allows hydrologic users real-time access to NEXRAD radar data in support of a wide range of research. The system processes basic radar data (Level II) and delivers radar-rainfall products based on the user's custom selection of features such as spatial domain, rainfall product space and time resolution, and rainfall estimation algorithms. HNX2 collects real-time, unprocessed data from multiple NEXRAD radars as they become available, processes them through a user-configurable pipeline of data-processing modules, and publishes the processed data-products at regular intervals. Modules in the data-processing pipeline encapsulate algorithms such as non-meteorological echo detection, …

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Performance Enhancement Of Crumb Rubber-Modified Asphalts Through Control Of The Developed Internal Network Structure, Mohyeldin Ragab, Magdy Abdelrahman, Amir Ghavibzaoo Jan 2013

Performance Enhancement Of Crumb Rubber-Modified Asphalts Through Control Of The Developed Internal Network Structure, Mohyeldin Ragab, Magdy Abdelrahman, Amir Ghavibzaoo

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Control of the internal network structure of crumb rubber-modified asphalt (CRMA) was investigated for its effect on property development in the study presented in this paper. The investigation included evaluation by rheological and interrupted shear tests. Rheological testing involved the monitoring of the changes of the produced complex modulus (G*) and phase angle (δ) for CRMA. In the interrupted shear tests, the shear stress profile for the produced CRMA was investigated. It was found that triggering the critical conditions of the combined interaction of speed, temperature, and time was essential to inducing the formation of the three-dimensional network …

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Scale Of Fluctuation Of Geotechnical Parameters Estimated From Cptu And Laboratory Test Data, Site Onyejekwe, Louis Ge Jan 2013

Scale Of Fluctuation Of Geotechnical Parameters Estimated From Cptu And Laboratory Test Data, Site Onyejekwe, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

For a complete probabilistic characterization of a geotechnical parameter, its mean, variance, and the scale of fluctuation have to be known. While the mean and variance can be easily determined, determination of the scale of fluctuation is a little more complex. Knowledge of the scale of fluctuation is important in reliability-based design as it is used in implementing spatial averaging and computing the variance-reduction factor. Published values of scale of fluctuation of geotechnical parameters are based on widely sourced data and hence may not be most appropriate for local situations. Based on 11 CPTu soundings and laboratory test results of …

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Probability Of Failure For Slopes With Sensitivity Analysis, Michelle Deng, Ronaldo Luna Jan 2013

Probability Of Failure For Slopes With Sensitivity Analysis, Michelle Deng, Ronaldo Luna

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The significance of random variables on the probability of failure of slopes is generally evaluated by changing a different set of values for each variable and repeating the approach several times to conclude a trend. This method is very straightforward but requires time and computational resources; and it is inefficient especially when the number of random variables is large. This paper presents an analysis approach in which the sensitivity analysis is introduced to quantify the influence of the random variables on the probability of failure for slopes. In this study, the factor of safety of the slope was determined using …

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Appropriate Viscous Damping For Nonlinear Time-History Analysis Of Base-Isolated Reinforced Concrete Buildings, Deepak R. Pant, Anil C. Wijeyewickrema, Mohamed A. Elgawady Jan 2013

Appropriate Viscous Damping For Nonlinear Time-History Analysis Of Base-Isolated Reinforced Concrete Buildings, Deepak R. Pant, Anil C. Wijeyewickrema, Mohamed A. Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

SUMMARY: There is no consensus at the present time regarding an appropriate approach to model viscous damping in nonlinear time-history analysis of base-isolated buildings because of uncertainties associated with quantification of energy dissipation. Therefore, in this study, the effects of modeling viscous damping on the response of base-isolated reinforced concrete buildings subjected to earthquake ground motions are investigated. The test results of a reduced-scale three-story building previously tested on a shaking table are compared with three-dimensional finite element simulation results. The study is primarily focused on nonlinear direct-integration time-history analysis, where many different approaches of modeling viscous damping, developed within …

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The Guayule Plant: A Renewable, Domestic Source Of Binder Materials For Flexible Pavement Mixtures, David Newton Richardson, Steven Michael Lusher Jan 2013

The Guayule Plant: A Renewable, Domestic Source Of Binder Materials For Flexible Pavement Mixtures, David Newton Richardson, Steven Michael Lusher

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Due to the rising price of crude oil, flexible pavement costs have increased significantly. This price pressure has resulted in the increased use of reclaimed asphalt pavement (RAP) and/or reclaimed asphalt roofing shingles (RAS) because of the binder (asphalt cement) they contain. This has increased demand for recycling (rejuvenating) agents which return the RAP/RAS binders to their original state by 1) restoring maltenes (petroleum oils and resins) that have been depleted due to age-hardening/oxidation, and 2) reducing their viscosity. The project concept was to design a flexible pavement mixture (FPM) produced with little-to-no virgin petroleumbased binder which implied the use …

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Enamel Coated Steel Reinforcement For Improved Durability And Life-Cycle Performance Of Concrete Structures: Microstructure, Corrosion, And Deterioration, Fujian Tang Jan 2013

Enamel Coated Steel Reinforcement For Improved Durability And Life-Cycle Performance Of Concrete Structures: Microstructure, Corrosion, And Deterioration, Fujian Tang

Doctoral Dissertations

"This study is aimed (a) to statistically characterize the corrosion-induced deterioration process of reinforced concrete structures (concrete cracking, steel mass loss, and rebar-concrete bond degradation), and (b) to develop and apply three types of enamel-coated steel bars for improved corrosion resistance of the structures. Commercially available pure enamel, mixed enamel with 50% calcium silicate, and double enamel with an inner layer of pure enamel and an outer layer of mixed enamel were considered as various steel coatings. Electrochemical tests were respectively conducted on steel plates, smooth bars embedded in concrete, and deformed bars with/without concrete cover in 3.5 wt.% NaCl …

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Phytoforensics On Energetics: Novel Plant Tissue Measure Approach And Modeling, Yuan Yuan Jan 2013

Phytoforensics On Energetics: Novel Plant Tissue Measure Approach And Modeling, Yuan Yuan

Doctoral Dissertations

"Explosives and energetics are common soil and groundwater pollutions. This research was to develop novel phytoforensics approaches on energetics. Four different plants species, including woody perennial trees and monocot grasses, were planted both in soil and sand reactors with continuous exposure to a mixture of explosives in the greenhouse. Time dependent assessments were carried out to determine kinetic mechanisms of uptake, transport and accumulation. Plant concentrations were analyzed by both traditional solvent extraction and novel sap analysis methods. A dynamic soil-plant system model was developed to quantify the relationship between tissue concentration and soil pore water concentration for non-volatile organic …

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