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2014

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Articles 61 - 76 of 76

Full-Text Articles in Architectural Engineering

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 …


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 …


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 …


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 …


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 …


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, …


The Potential For Energy Reduction In Uk Commercial Offices Through Effective Management And Behaviour Change, Mark Mulville, Keith Jones, Gesche Huebner Jan 2014

The Potential For Energy Reduction In Uk Commercial Offices Through Effective Management And Behaviour Change, Mark Mulville, Keith Jones, Gesche Huebner

Articles

eneral office equipment can be responsible for a significant proportion of overall electrical energy consumption in UK offices and this is predicted to rise significantly over the coming years [Webber, C. A., Roberson, J. A., Brown, R. E., Payne, C. T., Nordman, B., & Koomey, J. G. (2001). Field surveys of office equipment operating patterns. Berkley: CA: Lawrence Berkley National Laboratory]. As a significant contributor to overall energy use, this equipment has a corresponding cost and carbon impact. The legally binding requirements of the climate change act [Department of Energy and Climate Change. (2008 Department of Energy and …


A Transient Community For A Transient Lifestyle, Sameh Mohamed Ibrahim Jan 2014

A Transient Community For A Transient Lifestyle, Sameh Mohamed Ibrahim

Theses and Dissertations

The project suggests an alternative means for living in Qatar. It proposes the development of a transient, floating community a man-made, transitory archipelago of floating housing units located at the ‘soon to be abandoned’ docks a short distance from the Museum of Islamic Art and the Doha Corniche. The design, through a variety of bespoke dwelling options, can provide both more and less nomadic housing to accommodate a variety of dif- ferent lifestyles and social units. Clustered around three permanent islands (containing a cultural/activity center, three adaptable ‘work-unit’ towers, and a park/commercial area), the design provides a wide set of …


Summary Of Large-Scale C-Shaped Reinforced Concrete Wall Tests, Anahid A. Behrouzi, Andrew Mock, Laura Lowes, Dawn Lehman, Daniel Kuchma Jan 2014

Summary Of Large-Scale C-Shaped Reinforced Concrete Wall Tests, Anahid A. Behrouzi, Andrew Mock, Laura Lowes, Dawn Lehman, Daniel Kuchma

Architectural Engineering

Flexural concrete walls (i.e., walls the yield in flexural prior to failure) are used commonly as the lateral load resisting system for mid‐ and high‐rise buildings on the West Coast. They are relatively stiff under service‐level loading, can take on various configurations to accommodate architectural constraints, and are generally assumed to exhibit ductile response under severe earthquake loading. Despite heavy reliance on concrete walls, relatively little research has been done to investigate the earthquake performance of walls with modern design details. Few data exist characterizing the performance of modern walls under variable levels of earthquake loading or the impact of …


The Influence Of National Culture On Effectiveness Of Safety Trainings During Postdisaster Reconstruction, Behzad Esmaeili, Kevin Grosskopf, Amy Javernick-Will Jan 2014

The Influence Of National Culture On Effectiveness Of Safety Trainings During Postdisaster Reconstruction, Behzad Esmaeili, Kevin Grosskopf, Amy Javernick-Will

Durham School of Architectural Engineering and Construction: Faculty Publications

Non-English speaking workers constitute a disproportionately high number of workers involved in postdisaster reconstruction. Additionally, the rate of fatality among these workers is higher than the industry average. Research shows this population is more prone to unsafe behaviors in the working environment, conceivably because many of these workers are sent into the field prior to any formalized training. Recent studies show that the native culture of construction workers can impact risk-taking behavior. While numerous researchers have attempted to develop training materials for Hispanic workers, the number of studies that consider the impact of native culture on safety behavior is minimal. …


Development Of A Tribometer To Characterize Lubrication Layer Properties Of Self-Consolidating Concrete, Dimitri Feys, Kamal Khayat, Aurelien Perez-Schell, Rami Khatib Jan 2014

Development Of A Tribometer To Characterize Lubrication Layer Properties Of Self-Consolidating Concrete, Dimitri Feys, Kamal Khayat, Aurelien Perez-Schell, Rami Khatib

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Last Decade, Significant Advances Have Been Made in Investigating, Understanding and Predicting the Flow Characteristics during Pumping of Concrete. Kaplan Developed Theoretical Equations based on the Rheological and Tribological Properties of Concrete to Predict Pumping Pressures. Several Tribometers Were Developed to Characterize the Flow Properties of Concrete Along a Smooth Wall, But None of Them Allows the Use of Highly Workable Concretes. the Main Reason is that for the Calculation of the Yield Stress and Viscous Constant of the Lubrication Layer, the Concrete is Not Allowed to Be Sheared. in This Paper, a New Design for the Concrete Tribometer …


Virtual Surface Temperature Sensor For Multi-Zone Commercial Buildings, Yuebin Yu, Denchai Woradechjumroen, Daihong Yu Jan 2014

Virtual Surface Temperature Sensor For Multi-Zone Commercial Buildings, Yuebin Yu, Denchai Woradechjumroen, Daihong Yu

Durham School of Architectural Engineering and Construction: Faculty Publications

Multi-zone structure is commonly used in small commercial office buildings, retail stores and supermarket. While there is no adjacent wall between the zones, the impact of a neighbor zone on the current zone can be approximated and analyzed through the application of virtual walls. It is critical to accurately estimate the virtual wall surface temperature in order to evaluate the model uncertainty and apply improved supervisory control on multiple rooftop air-conditioning units (RTUs). We propose an innovative virtual surface temperature sensor based on system-identification to solve this challenge. The validation of the virtual temperature model is processed by the three …


Shallow Flat Soffit Precast Concrete Floor System, George Morcous, Maher Tadros Jan 2014

Shallow Flat Soffit Precast Concrete Floor System, George Morcous, Maher Tadros

Durham School of Architectural Engineering and Construction: Faculty Publications

A precast concrete floor system that eliminates the need for column corbels and beam ledges while being very shallow. The main advantages of the present system include a span to-depth ratio of 30, a flat soffit, economy, consistency with prevailing erection techniques, and fire and corrosion protection. The present system consists of continuous precast columns, prestressed rectangular beams, hollow-core planks, and cast-in-place composite topping. Testing results have indicated that a 12 inch deep flat soffit precast floor system has adequate capacity to carry gravity loads (including 100 psf live load) in a 30 ft x 30 ft bay size. Testing …


Summary Of Large-Scale Nonplanar Reinforced Concrete Wall Tests, Anahid A. Behrouzi, Andrew Mock, Laura Lowes, Dawn Lehman, Daniel Kuchma Jan 2014

Summary Of Large-Scale Nonplanar Reinforced Concrete Wall Tests, Anahid A. Behrouzi, Andrew Mock, Laura Lowes, Dawn Lehman, Daniel Kuchma

Architectural Engineering

Nonplanar wall configurations are prevalent in engineering practice, yet relatively little research has addressed nonplanar walls and the earthquake response of these components remains poorly understood. A recent experimental test program conducted by the authors investigated the earthquake response of modern, ACI Code compliant C‐shaped walls subjected to unidirectional and bidirectional lateral loading. To compare the results of this study with previous experimental investigations conducted by others, this document examines laboratory tests of slender nonplanar walls available in the literature. Response histories, damage patterns, drift capacity and failure mechanisms are used to characterize the behavior of each nonplanar wall test …


Hybrid Of Natural Element Method (Nem) With Genetic Algorithm (Ga) To Find Critical Slip Surface, Shahriar Shahrokhabadi, Vahid Khoshfahm, Hamed Nabizadeh Rafsanjani Jan 2014

Hybrid Of Natural Element Method (Nem) With Genetic Algorithm (Ga) To Find Critical Slip Surface, Shahriar Shahrokhabadi, Vahid Khoshfahm, Hamed Nabizadeh Rafsanjani

Durham School of Architectural Engineering and Construction: Faculty Publications

One of the most important issues in geotechnical engineering is the slope stability analysis for determination of the factor of safety and the probable slip surface. Finite Element Method (FEM) is well suited for numerical study of advanced geotechnical problems. However, mesh requirements of FEM creates some difficulties for solution processing in certain problems. Recently, motivated by these limitations, several new Meshfree methods such as Natural Element Method (NEM) have been used to analyze engineering problems. This paper presents advantages of using NEM in 2D slope stability analysis and Genetic Algorithm (GA) optimization to determine the probable slip surface and …


Empirically Derived Effective Stiffness Expressions For Concrete Walls, Andrew Mock, Anahid A. Behrouzi, Laura Lowes, Dawn Lehman, Daniel Kuchma Jan 2014

Empirically Derived Effective Stiffness Expressions For Concrete Walls, Andrew Mock, Anahid A. Behrouzi, Laura Lowes, Dawn Lehman, Daniel Kuchma

Architectural Engineering

In most cases, analysis to determine component demands for seismic design of concrete buildings employs linear elastic models in which reduced, effective component stiffnesses are used. This document i) reviews the recommendations for defining the effective flexural, shear and axial stiffness of concrete walls that are included in current design codes, standards and guidelines and ii) compares these recommendations with stiffness expressions derived directly from experimental data by the authors and others. Section 2 reviews existing empirically derived and code‐, standard‐, and guideline‐based expressions for the effective stiffness of concrete walls. Section 3 presents the process used by the authors …