Open Access. Powered by Scholars. Published by Universities.®

Civil and Environmental Engineering Commons™

Open Access. Powered by Scholars. Published by Universities.®

Missouri University of Science and Technology

Discipline
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 1561 - 1590 of 7869

Full-Text Articles in Civil and Environmental Engineering

Corrosion-Resistant Glasses For Steel Enamels, Richard K. Brow, Signo Tadeu Dos Reis, Michael L. Koenigstein, Genda Chen Mar 2014

Corrosion-Resistant Glasses For Steel Enamels, Richard K. Brow, Signo Tadeu Dos Reis, Michael L. Koenigstein, Genda Chen

Materials Science and Engineering Faculty Research & Creative Works

A cementitious composite material wherein glass-coated steel rods are positioned in a cementitious matrix. The glass composition for coating the steel reinforcing rods includes between about 33-45 weight percent SiO2, 13.5-19.5 weight percent B2O3, 3.5-4.6 weight percent Al2O3, 4.0-13.5 weight percent K2O, 5.5-15.5 weight percent ZrO2, 8.6-15.9 weight percent Na2O, 4.6-5.1 weight percent CaO, 0.6-0.7 weight percent MnO2, 1.0-1.0 weight percent NiO, and 1.0-1.1 weight percent CoO. The glass composition is typically in compression on the rods at ambient temperatures, has a …

Go to article

An Experimental Investigation Of Crumb Rubber Concrete Confined By Fibre Reinforced Polymer Tubes, Osama Youssf, Mohamed Elgawady, Julie E. Mills, Xing Ma Feb 2014

An Experimental Investigation Of Crumb Rubber Concrete Confined By Fibre Reinforced Polymer Tubes, Osama Youssf, Mohamed Elgawady, Julie E. Mills, Xing Ma

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Due to the known loss of compressive strength experienced by crumb rubber concrete (CRC) compared with conventional concrete, there have been few applications explored to date for the structural use of these materials. This paper describes experimental work conducted to explore the possible future use of CRC for structural columns by evaluating the use of fiber reinforced polymer (FRP) confinement as a means of overcoming the material deficiencies (decreased compressive strength). The results indicated that the use of FRP to confine rubberized concrete effectively negates the decrease in strength and retains the advantages of increased ductility that arise from rubberized …

Go to article

Plant Translocation Of Organic Compounds: Molecular And Physicochemical Predictors, Matt A. Limmer, Joel Gerard Burken Feb 2014

Plant Translocation Of Organic Compounds: Molecular And Physicochemical Predictors, Matt A. Limmer, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Root-Soil Boundary Represents One of the Largest Global Biotic-Abiotic Mass-Transfer Interfaces and is a Primary Pollutant Entry Point to the Food Chain. This Interface is Also Critically Important in Phytoremediation Efforts and Herbicide Design. Experimental Data and Single-Parameter Models Have Resulted in the Current Understanding that Moderately Hydrophobic Organic Compounds Are Most Likely to Be Translocated by Plants, Although Recent Evidence Indicates Plants Can Also Translocate Some Hydrophilic Compounds. Molecular Descriptors Initially Applied for Drug Discovery and for Transmembrane Migration in Mammalian Systems Were Applied Here to Determine the Physicochemical Domains and Weighted Desirability Functions to Identify Compounds Amenable …

Go to article

Improving The Hydraulics Of Drinking Water Contact Tanks Using Random Packing Material, Taylor C. Barnett, Justin J. Kattnig, Subhas K. Venayagamoorthy, Gordon Whittaker Feb 2014

Improving The Hydraulics Of Drinking Water Contact Tanks Using Random Packing Material, Taylor C. Barnett, Justin J. Kattnig, Subhas K. Venayagamoorthy, Gordon Whittaker

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This study investigated the use of industrial packing material for increasing the hydraulic efficiency of small-scale, chlorine contact tanks used in drinking water treatment. The packing material used in the study was spherical, with porosities between 0.9 and 0.95 and a density less than that of water. A total of 67 tracer studies, conducted on laboratory-scale chlorine contact tank systems, investigated three sizes of packing material, two tank sizes, and two flow rates. Sodium chloride solution was injected as a continuous tracer and was monitored in the tank outflow through electrical conductivity. Several studies were validated with the use and …

Go to article

The Bridge Newsletter Spring 2014, Missouri University Of Science And Technology Feb 2014

The Bridge Newsletter Spring 2014, Missouri University Of Science And Technology

The Bridge Newsletter

-Reusing scrap tires
-Renaissance man
-Energy research published
-Follow your passion

Go to article

2014 Scholarly Productivity Report, Missouri University Of Science And Technology Jan 2014

2014 Scholarly Productivity Report, Missouri University Of Science And Technology

Civil, Architectural and Environmental Engineering Scholarly Productivity Reports

No abstract provided.

Go to article

Compressibility Characteristics Of Low-Plasticity Silt Before And After Liquefaction, Shuying Wang, Ronaldo Luna Jan 2014

Compressibility Characteristics Of Low-Plasticity Silt Before And After Liquefaction, Shuying Wang, Ronaldo Luna

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Low-plasticity silt is known to have a potential to liquefy during earthquakes. The compressibility characteristics could change before and after a dynamic event that produces liquefaction. This research investigates the liquefaction resistance and post liquefaction reconsolidation characteristics of Mississippi River Valley (MRV) silt using laboratory cyclic triaxial compression testing. The MRV silt experienced initial liquefaction under cyclic loading, and the results are presented as cyclic stress ratio versus loading cycle curve. After cyclic loading, the liquefied specimens were reconsolidated. Permeability did not change significantly as a result of liquefaction. The reconsolidation curves are more parallel to the compression line than …

Go to article

Characterization Of Shear Wave Velocity And Its Anisotropy In Uniform Granular Materials, Xin Kang, Bate Bate, Louis Ge Jan 2014

Characterization Of Shear Wave Velocity And Its Anisotropy In Uniform Granular Materials, Xin Kang, Bate Bate, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Small strain stiffness of granular materials is important to many engineering applications, such as earthquake engineering, pavement, machine foundation, embankment subjected to tidal impacts, and foundations for structures under wind loads. Shear wave velocity, which is an indicator of stiffness, was measured with a newly developed bender element testing system. Test data supported that this testing system is effective in evaluating the shear wave velocity and its anisotropy of uniform spherical granular materials, including glass beads, uniform medium, and fine sands. Influencing factors on the Vs such as grain size and applied stress were studied. Two components of the soil …

Go to article

Effects Of Mix Design Parameters And Rheological Properties On Dynamic Stability Of Self-Consolidating Concrete, B. Esmaeilkhanian, Kamal Khayat, A. Yahia, D. Feys Jan 2014

Effects Of Mix Design Parameters And Rheological Properties On Dynamic Stability Of Self-Consolidating Concrete, B. Esmaeilkhanian, Kamal Khayat, A. Yahia, D. Feys

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Stability is a crucial property for successful placement and performance of self-consolidating concrete (SCC). Dynamic stability refers to the segregation resistance of concrete during flow and is not thoroughly described in literature to date. In this research, a newly developed dynamic stability test, the Tilting-box test, was employed to evaluate the effect of different mix design parameters on the dynamic segregation of SCC. Paste volume, water-to-binder ratio (w/b), maximum size of aggregate (MSA), aggregate density, and aggregate grain-size distribution were shown to affect the dynamic stability of SCC, while the coarse aggregate shape did not have a significant influence. The …

Go to article

Effects Of Interaction Conditions On Internal Network Structure Of Crumb Rubber-Modified Asphalts, Mohyeldin Ragab, Magdy Abdelrahman Jan 2014

Effects Of Interaction Conditions On Internal Network Structure Of Crumb Rubber-Modified Asphalts, Mohyeldin Ragab, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Investigation of the effect of interaction conditions on the development of the internal network structure of crumb rubber-modified asphalt (CRMA) was carried out. Enhancements in the CRMA physical properties, such as stiffness, expressed in the complex modulus (G*), and elasticity, expressed in the phase angle (δ), as a result of the development of three-dimensional (3-D) entangled network structure were achieved. These results came from controlling the interaction conditions of CRMA synthesis to regulate the crumb rubber-modified (CRM) components that were responsible for the formation of the 3-1) entangled network structure. Dissolution tests and thermogravimetric analysis (TGA) were performed on the …

Go to article

Cyber-Physical Codesign Of Distributed Structural Health Monitoring With Wireless Sensor Networks, Gregory Hackmann, Weijun Guo, Guirong Yan, Zhuoxiong Sun, Chenyang Lu, Shirley Dyke Jan 2014

Cyber-Physical Codesign Of Distributed Structural Health Monitoring With Wireless Sensor Networks, Gregory Hackmann, Weijun Guo, Guirong Yan, Zhuoxiong Sun, Chenyang Lu, Shirley Dyke

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Our Deteriorating Civil Infrastructure Faces the Critical Challenge of Long-Term Structural Health Monitoring for Damage Detection and Localization. in Contrast to Existing Research that Often Separates the Designs of Wireless Sensor Networks and Structural Engineering Algorithms, This Paper Proposes a Cyber-Physical Codesign Approach to Structural Health Monitoring based on Wireless Sensor Networks. Our Approach Closely Integrates 1) Flexibility-Based Damage Localization Methods that Allow a Tradeoff between the Number of Sensors and the Resolution of Damage Localization, and 2) an Energy-Efficient, Multilevel Computing Architecture Specifically Designed to Leverage the Multiresolution Feature of the Flexibility-Based Approach. the Proposed Approach Has Been Implemented …

Go to article

Linking Solid Particle Packing Of Eco-Scc To Material Performance, Florian V. Mueller, Olafur H. Wallevik, Kamal Khayat Jan 2014

Linking Solid Particle Packing Of Eco-Scc To Material Performance, Florian V. Mueller, Olafur H. Wallevik, Kamal Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The concept of Eco-SCC aims to achieve self-compacting concrete (SCC) design for intermediate compressive strength mixtures that are commonly used in the ready-mix concrete industry. Contrary to many other approaches, in which the reactive cement clinker is replaced by a less reactive component, Eco-SCC involves the reduction of the total powder content. In the approach presented in this paper, the lubricant volume is increased by using a non-reactive filler. An improved particle packing with an enhanced lattice effect can minimize the lubricant demand and enhance the stability of the concrete. The effect of particle-size distribution on stability and performance of …

Go to article

Parametric Analysis Of Resilient Modulus Modeling For Recycled Asphalt Pavement In Base Layer, Ehab Noureldin, Magdy Abdelrahman Jan 2014

Parametric Analysis Of Resilient Modulus Modeling For Recycled Asphalt Pavement In Base Layer, Ehab Noureldin, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The resilient modulus (MR) has been found to be the most important parameter in the Mechanistic-Empirical Pavement Design Guide (MEPDG) for the base layer. A literature review showed that the use of recycled asphalt pavement (RAP) in the base layer had many economic and structural benefits. The prediction of MR with the specific MEPDG model for the base layer mixed with RAP was found to be reliable for several field conditions. However, further studies of the MEPDG model are needed for an understanding of the physical meaning of each parameter in the model. The most important factor …

Go to article

Effect Of Crumb Rubber Dissolution On Low-Temperature Performance And Aging Of Asphalt-Rubber Binder, Amir Ghavibazoo, Magdy Abdelrahman Jan 2014

Effect Of Crumb Rubber Dissolution On Low-Temperature Performance And Aging Of Asphalt-Rubber Binder, Amir Ghavibazoo, Magdy Abdelrahman

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Asphalt binder plays a critical role in defining the low-temperature performance of asphalt pavement, and, therefore, enhancing its mechanical behavior at low service temperatures through modification always has been of great interest. Crumb rubber modification of asphalt is one of the common practices in the industry. However, the effect of a crumb rubber modifier (CRM) on low-temperature performance of the binder is not well understood. A CRM swells by absorbing the aromat-ics and light molecular components of asphalt at low interaction temperatures (i.e., 160°C) and dissolves at higher interaction temperatures (i.e., 190°C, 220°C). Each of those activities affects the performance …

Go to article

Impact Of Organic Coatings On Frictional Strength Of Organically Modified Clay, B. Bate, Q. Zhao, S. E. Burns Jan 2014

Impact Of Organic Coatings On Frictional Strength Of Organically Modified Clay, B. Bate, Q. Zhao, S. E. Burns

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Organic matter is frequently encountered in both naturally occurring and engineered particulate media. Charged functional groups in the organic matter can lead to cation exchange within the clay interlayer, which results in the formation of an organic coating on the clay surfaces and alters the interfacial frictional regime in the soil mass. This study investigated the triaxial shear frictional behavior of montmorillonite particles coated with a controlled organic phase composed of quaternary ammonium cations. Through cation exchange, organic cations were loaded onto the clay's interlayer exchange sites, with control on the density of organic coverage and structure of the organic …

Go to article

Effects Of Chemical Stabilizers On An Expansive Clay, Honghua Zhao, Louis Ge, Thomas M. Petry, Yi Zhen Sun Jan 2014

Effects Of Chemical Stabilizers On An Expansive Clay, Honghua Zhao, Louis Ge, Thomas M. Petry, Yi Zhen Sun

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Expansive clays exhibit a high potential for the volume change behavior when the soil moisture changes. The estimated annual cost of the damage to the facilities built on expansive clay in the United States exceeds 9 billion dollars. Because of the physicochemical nature of the expansive clay, the use of chemical agents to improve their engineering properties is common. This research investigated the effects of chemical agents on an expansive soil from Texas through a laboratory injection method. The agents used in this study included lime, potassium-based agents, and a group of ionic agents. Swelling tests, chemical tests, and soil …

Go to article

A Simple Turbulence Model For Stably Stratified Wall-Bounded Flows, F. Karimpour, S. K. Venayagamoorthy Jan 2014

A Simple Turbulence Model For Stably Stratified Wall-Bounded Flows, F. Karimpour, S. K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this study, we present a simple zero-equation (algebraic) turbulence closure scheme as well as the standard k-Ïμ model for stably stratified wall-bounded flows. We do this by proposing a parameterization for the turbulent Prandtl number (Prt) for stably stratified flows under the influence of a smooth solid wall. The turbulent Prandtl number is the linking bridge between the turbulent momentum and scalar fluxes in the context of Reynolds-averaged Navier-Stokes (RANS) simulations. Therefore, it is important to use appropriate parameterizations for Prt in order to define the right level of momentum and scalar mixing in stably stratified flows. To date, …

Go to article

Study On Surface Permeability Of Concrete Under Immersion, Jun Liu, Feng Xing, Biqin Dong, Hongyan Ma, Dong Pan Jan 2014

Study On Surface Permeability Of Concrete Under Immersion, Jun Liu, Feng Xing, Biqin Dong, Hongyan Ma, Dong Pan

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, concrete specimens are immersed in ultrapure water, to study the evolutions of surface permeability, pore structure and paste microstructure following the prolonging of immersion period. According to the results, after 30-day immersion, the surface permeability of concrete becomes higher as compared with the value before immersion. However, further immersion makes the surface permeability decrease, so that the value measured after 150-day immersion is only half that measured after 30-day immersion. The early increase in surface permeability should be mainly attributed to the leaching of calcium hydroxide, while the later decrease to the refinement of pore structure due …

Go to article

Shear Strength Of Chemically Based Self-Consolidating Concrete Beams: Fracture Mechanics Approach Versus Modified Compression Field Theory, Mahdi Arezoumandi, Jeffery S. Volz Jan 2014

Shear Strength Of Chemically Based Self-Consolidating Concrete Beams: Fracture Mechanics Approach Versus Modified Compression Field Theory, Mahdi Arezoumandi, Jeffery S. Volz

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

An experimental investigation was conducted to study the shear strength of full-scale beams constructed with both chemically based self-consolidating concrete (SCC) and conventional concrete (CC). This experimental program consisted of 12 beams without stirrups with three different longitudinal reinforcement ratios. The beams were tested under a simply supported four-point loading condition. The experimental shear strengths of the beams were compared with the shear provisions of both U.S. and international design codes. Furthermore, the shear strengths of the beams were evaluated based on fracture mechanics approaches, modified compression field theory (MCFT), and a shear database of CC specimens. Results of this …

Go to article

Safety Effect Of Missouri's Strategic Highway Safety Plan: Missouri's Blueprint For Safer Roadways, Mojtaba A. Mohammadi, V. A. Samaranayake, Ghulam H. Bham Jan 2014

Safety Effect Of Missouri's Strategic Highway Safety Plan: Missouri's Blueprint For Safer Roadways, Mojtaba A. Mohammadi, V. A. Samaranayake, Ghulam H. Bham

Mathematics and Statistics Faculty Research & Creative Works

This study systematically evaluated the changes in motor vehicle crashes that occurred on the Missouri Interstate highway system following the implementation of the Missouri Strategic Highway Safety Plan (MSHSP) between 2004 and 2007. The MSHSP implemented crash injury reduction strategies in enforcement, education, engineering, and public policy. Empirical Bayesian methods were commonly used to evaluate the effects of any change in safety as a result of countermeasures. This paper presents a simple new approach to evaluating the effects of Missouri's safety plans on roadway crashes. For crash data associated with traffic and roadway characteristics, negative binomial regression models were developed …

Go to article

Full-Scale Field Testing Of Micropiles In Stiff Clay Subjected To Combined Axial And Lateral Loads, Kyle A. Kershaw, Ronaldo Luna Jan 2014

Full-Scale Field Testing Of Micropiles In Stiff Clay Subjected To Combined Axial And Lateral Loads, Kyle A. Kershaw, Ronaldo Luna

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A series of full-scale micro piles was installed at a site in mid-Missouri for a load-test program to study the effect of combined loading. The micro piles were installed with a 178-mm (7-in.) outer diameter steel casing to a depth of 4.6 m (15 ft) and a bond zone length of 3.0 m (10 ft). The surficial soils at the site consisted of stiff-to-hard clay underlain by weathered silty/sandy shale where the bond zone of the micro piles was located. The load-test program included axial, lateral, and combined-load tests. The ultimate axial and lateral capacity of the piles was initially …

Go to article

Thermophysical And Mechanical Properties Of Hardened Cement Paste With Microencapsulated Phase Change Materials For Energy Storage, Hongzhi Cui, Wenyu Liao, Shazim Ali Memon, Biqin Dong, Waiching Tang Jan 2014

Thermophysical And Mechanical Properties Of Hardened Cement Paste With Microencapsulated Phase Change Materials For Energy Storage, Hongzhi Cui, Wenyu Liao, Shazim Ali Memon, Biqin Dong, Waiching Tang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this research, structural-functional integrated cement-based materials were prepared by employing cement paste and a microencapsulated phase change material (MPCM) manufactured using urea-formaldehyde resin as the shell and paraffin as the core material. The encapsulation ratio of the MPCM could reach up to 91.21 wt%. Thermal energy storage cement pastes (TESCPs) incorporated with different MPCM contents (5%, 10%, 15%, 20% and 25% by weight of cement) were developed, and their thermal and mechanical properties were studied. The results showed that the total energy storage capacity of the hardened cement specimens with MPCM increased by up to 3.9-times compared with that …

Go to article

Role Of Solids Retention Time On Complete Nitrification: Mechanistic Understanding And Modeling, Guoqiang Liu, Jianmin Wang Jan 2014

Role Of Solids Retention Time On Complete Nitrification: Mechanistic Understanding And Modeling, Guoqiang Liu, Jianmin Wang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Effects of solids retention time (SRT) on both steps of the nitrification process (e.g., ammonia oxidation and nitrite oxidation) and the nitrifier community in a complete-mix activated sludge process were studied. At a SRT less than or equal to 20 days, the effluent ammonia concentration was lower than the effluent nitrite concentration. At the 40-day SRT, however, the effluent nitrite concentration became equal to or less than the effluent ammonia concentration. Quantitative Polymerase Chain Reaction (QPCR) assays indicated that increasing SRT significantly increased nitrite-oxidizing bacteria/ammonia-oxidizing bacteria (NOB/AOB) ratio. Further investigation indicated that Nitrosomonas europaea/eutropha were the dominant AOB for ammonia …

Go to article

Spatial And Temporal Modeling Of Radar Rainfall Uncertainties, Gabriele Villarini, Bong Chul Seo, Francesco Serinaldi, Witold F. Krajewski Jan 2014

Spatial And Temporal Modeling Of Radar Rainfall Uncertainties, Gabriele Villarini, Bong Chul Seo, Francesco Serinaldi, Witold F. Krajewski

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

It is widely acknowledged that radar-based estimates of rainfall are affected by uncertainties (e.g., mis-calibration, beam blockage, anomalous propagation, and ground clutter) which are both systematic and random in nature. Improving the characterization of these errors would yield better understanding and interpretations of results from studies in which these estimates are used as inputs (e.g., hydrologic modeling) or initial conditions (e.g., rainfall forecasting). Building on earlier efforts, the authors apply a data-driven multiplicative model in which the relationship between true rainfall and radar rainfall can be described in terms of the product of a systematic and random component. The systematic …

Go to article

Form Pressure Generated By Fresh Concrete: A Review About Practice In Formwork Design, Tilo Proske, Kamal Khayat, Ahmed Omran, Olaf Leitzbach Jan 2014

Form Pressure Generated By Fresh Concrete: A Review About Practice In Formwork Design, Tilo Proske, Kamal Khayat, Ahmed Omran, Olaf Leitzbach

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In this paper, several current industrial practices in formwork design are presented focusing on the normative calculation of the form pressure. Most of the current Standards are devoting for the design of the formwork for the normal vibrated concrete. Currently, the Standards are being updated to include provisions for the newly adapted concrete, such as the flowable concrete and self-consolidating concrete. However, the experience with these methods is still limited. The available methods for calculating the formwork pressure for the flowable concrete and SCC are based on measuring the shear strength of concrete using different concepts, such as the setting …

Go to article

Use Of Innovative Techniques To Enhance The Hydraulic Disinfection Efficiency Of Drinking Water Contact Tanks, J. J. Kattnig, S. K. Venayagamoorthy Jan 2014

Use Of Innovative Techniques To Enhance The Hydraulic Disinfection Efficiency Of Drinking Water Contact Tanks, J. J. Kattnig, S. K. Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The focus of this study was to understand the complex nature of flow dynamics within water disinfection contact tanks and to use this understanding in the development of beneficial tank modifications. Methods involved in this process included the use of computational fluid dynamics (CFD) and physical conservative tracer studies. Attempted tank alterations included the installation of baffles, inlet modification, and the use of industrial packing material. Tested modifications aimed at altering existing velocity fields to increase the hydraulic disinfection efficiency of a given system. Hydraulic efficiency was measured through the use of residence time distribution (RTD) curves and the well-known …

Go to article

Behavior Of Hybrid Frp-Concrete-Steel Double-Skin Tubes Subjected To Cyclic Axial Compression, Omar I. Abdelkarim, Mohamed A. Elgawady Jan 2014

Behavior Of Hybrid Frp-Concrete-Steel Double-Skin Tubes Subjected To Cyclic Axial Compression, Omar I. Abdelkarim, Mohamed A. Elgawady

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

This paper presents the results of an experimental study that was conducted to investigate the effects of key parameters on the compressive behavior of fiber-reinforced polymer (FRP)-concrete-steel double-skin tubular columns (FSDT). Hybrid FSDT columns have been introduced as a new form of hybrid columns. They consist of an outer tube made of FRP and inner tub made of steel, with sandwiched concrete between them. This paper investigated the effect of fiber angle and the ratio of steel tube diameter to its thickness (Di/ts) on the compressive behavior of FSDT columns. Six FSDT cylinders with different (Di/ts), in addition to two …

Go to article

Choice Of Thixotropic Index To Evaluate Formwork Pressure Characteristics Of Self-Consolidating Concrete, Ahmed F. Omran, Kamal H. Khayat Jan 2014

Choice Of Thixotropic Index To Evaluate Formwork Pressure Characteristics Of Self-Consolidating Concrete, Ahmed F. Omran, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Formwork lateral pressure exerted by concrete is affected by mixture composition, placement conditions, and formwork characteristics. The mixture composition includes binder type and content, supplementary cementitious materials, fillers, water-to-cementitious ratio, content and characteristics of coarse aggregate, paste volume, chemical admixtures, concrete unit weight, concrete consistency, and temperature. Thixotropy of concrete expressed here in terms of structural build-up at rest is employed to collectively reflect the effect of combined mix design factors on formwork pressure. This research demonstrates relationships between 12 indices that can be used to evaluate the structural build-up at rest of concrete, determined using portable vane, inclined plane, …

Go to article

Four-Dimensional Reflectivity Data Comparison Between Two Ground-Based Radars: Methodology And Statistical Analysis, Bong Chul Seo, Witold F. Krajewski, James A. Smith Jan 2014

Four-Dimensional Reflectivity Data Comparison Between Two Ground-Based Radars: Methodology And Statistical Analysis, Bong Chul Seo, Witold F. Krajewski, James A. Smith

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A methodology is proposed to compare radar reflectivity data obtained from two partially overlapping ground-based radars in order to explain relative differences in radar-rainfall products and establish sound merging procedures for multi-radar observing networks. To identify radar calibration differences, radar reflectivity is compared for well-matched radar sampling volumes viewing common meteorological targets. Temporal separation and three-dimensional matching of two different sampling volumes were considered based on the original polar coordinates of radar observation. Since the proposed method assumes radar beam propagation under standard atmospheric conditions, anomalous propagation cases were eliminated from the analysis. The reflectivity comparison results show systematic differences …

Go to article

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 …

Go to article

First Prev Next Last