Architectural Engineering Commons^™

Numerical Simulation Of Vortex-Induced Vibration Of Two Circular Cylinders Of Different Diameters At Low Reynolds Number, Ming Zhao, Guirong Yan

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Two-Degree-Of-Freedom Vortex-Induced Vibration (VIV) of Two Rigidly Coupled Circular Cylinders of Different Diameters at a Low Reynolds Number of 250 is Investigated Numerically. While the Diameter Ratio and the Mass Ratio Are Kept Constant, the Study is Focused on the Effect of the Position Angle of the Small Cylinder on the Lock-In Regime of the VIV. Simulations Are Carried Out for Position Angles Α of the Small Cylinder Ranging from 0° to 180° with an Interval of 22.5° and the Reduced Velocities Ranging from 1 to 15 with an Increment of 1. in Order to Find the Effect of the …

Directional Phytoscreening: Contaminant Gradients In Trees For Plume Delineation, Matt A. Limmer, Mikhil K. Shetty, Samantha Markus, Ryan Kroeker, Beth L. Parker, Camilo Martinez, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Tree Sampling Methods Have Been Used in Phytoscreening Applications to Delineate Contaminated Soil and Groundwater, Augmenting Traditional Investigative Methods that Are Time-Consuming, Resource-Intensive, Invasive, and Costly. in the Past Decade, Contaminant Concentrations in Tree Tissues Have Been Shown to Reflect the Extent and Intensity of Subsurface Contamination. This Paper Investigates a New Phytoscreening Tool: Directional Tree Coring, a Concept Originating from Field Data that Indicated Azimuthal Concentrations in Tree Trunks Reflected the Concentration Gradients in the Groundwater Around the Tree.To Experimentally Test This Hypothesis, Large Diameter Trees Were Subjected to Subsurface Contaminant Concentration Gradients in a Greenhouse Study. These Trees …

Dynamic Properties Of Fine-Grained Soils Engineered With A Controlled Organic Phase, B. Bate, H. Choo, S. E. Burns

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Soils with high organic content are frequently encountered beneath earthquake sensitive infrastructure, such as bridges or levees. Historically, the dynamic properties of these organically rich soils have been difficult to predict due to the heterogeneity of the natural organic matter that is found in natural soils, even though their response to dynamic loading remains critical to assessing the ongoing stability of the infrastructure. In this study, an experimental investigation was performed on a montmorillonite soil that was modified with a controlled organic phase. Quaternary ammonium cations were exchanged onto the soil particle surfaces through cation exchange with the clay's naturally …

Relevance Of The Thorpe Length Scale In Stably Stratified Turbulence, Benjamin D. Mater, Simon M. Schaad, Subhas Karan Venayagamoorthy

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Direct numerical simulations of stably stratified turbulence are used to compare the Thorpe overturn length scale, LT, with other length scales of the flow that can be constructed from large-scale quantities fundamental to shear-free, stratified turbulence. Quantities considered are the turbulent kinetic energy, k, its dissipation rate, ε, and the buoyancy frequency, N. Fundamental length scales are then the Ozmidov length scale, LO, the isotropic large scale, Lkε, and a kinetic energy length scale, LkN. Behavior of all three fundamental scales, relative to LT, is shown to be a function of the buoyancy strength parameter NTL, where TL = k/ε …

Modified Time Of Setting Test For Fly Ash Paste And Fly Ash-Soil Mixtures, Xin Kang, Gi Chun Kang, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

A survey of current literature has revealed that the testing protocol for determining the time of setting of fly ash-soil mixtures is not available. Although the current ASTM standard recommends using the Vicat needle method with a water-to-fly ash weight ratio of 0.35, it was originally proposed for testing the time of setting of cement. The current study showed that the Vicat needle method yielded poor test results for some common fly ashes. Moreover, the water-to-fly ash weight ratio of 0.35 may not be appropriate for some fly ashes because the chemical components are varied in different fly ashes. Therefore, …

Centrifuge Modeling And Mitigation Of Manhole Uplift Due To Liquefaction, Gi Chun Kang, Tetsuo Tobita, Susumu Iai, Louis Ge

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Because low-compacted trench backfill around a manhole is normally liquefiable, the manhole could suffer uplift damage associated with soil liquefaction during a strong earthquake. In this study, 22 dynamic centrifuge models were tested to investigate the response of a buried manhole subjected to a dynamic load. The models were tested under 20g, and a substitute pore fluid was used to avoid the scaling law conflict between the dynamic and diffusion processes. It was found that excess pore water pressure is one of the contributing factors to the magnitude of the manhole uplift. Using this result, new mitigation methods against the …

Portable Pressure Device To Evaluate Lateral Formwork Pressure Exerted By Fresh Concrete, Ahmed F. Omran, Kamal H. Khayat

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

Use of a reliable and accurate measuring system to determine lateral pressure exerted on formwork by self-consolidating concrete can lead to economic and safe formwork systems. In this paper, a portable and field-compatible pressure device is developed to enable factors affecting lateral pressure of fresh concrete on formwork system to be explored prior to conducting onsite full-scale tests. The pressure device requires a sample of 16 L of fresh concrete to determine lateral pressure envelope that can be exerted by a concrete column of up to 13 m in height. The pressure device enables the simulation of such concrete head …

Wind-Induced Torsion Vibration Of The Super High-Rise Building Of Shenzhen Energy Center, Feng Ruo-Qiang, Ye Jihong, Guirong Yan, Li Qing-Xiang, Yao Bin

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Synchronous Multipoint Scanning System Technique in Wind Tunnel Tests and Random Vibration Theory Method Were Used to Analyze the Wind-Induced Torsion Vibration of Some Irregularly Shaped Super High-Rise Buildings in Downtowns. the Torsion Vibration Modes and the Spectra of Torsion Wind Load Were Studied, and the Proportions of Mean Wind Torsion, Inertia Torsion and the Mass Eccentricity Torsion Caused by Horizontal Inertia Forces Are Discussed. the Following Conclusions Can Be Drawn. First, the Third and Fourth Modes Have Torsion Vibration Shapes, and their Frequencies Are in the High-Energy Area of the Spectra of the Torsion Wind Load; the Third …

Seismic Performance Comparison Of A Fixed-Base Versus A Base-Isolated Office Building, Nicholas Reidar Marrs

Master's Theses

The topic of this thesis is base isolation. The purpose of this thesis is to offer a relative understanding of the seismic performance enhancements that a typical 12-story steel office building can achieve through the implementation of base isolation technology. To reach this understanding, the structures of a fixed-base office building and a base-isolated office building of similar size and layout are designed, their seismic performance is compared, and a cost-benefit analysis is completed. The base isolation system that is utilized is composed of Triple Friction Pendulum (TFP) bearings.

The work of this thesis is divided into four phases. First, …

Long-Term Low Do Enriches And Shifts Nitrifier Community In Activated Sludge, Guoqiang Liu, Jianmin Wang

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

In the activated sludge process, reducing the operational dissolved oxygen (DO) concentration can improve oxygen transfer efficiency, thereby reducing energy use. The low DO, however, may result in incomplete nitrification. This research investigated the long-term effect of low DO on the nitrification performance of activated sludge. Results indicated that, for reactors with 10- and 40-day solids retention times (SRTs), complete nitrification was accomplished after a long-term operation with a DO of 0.37 and 0.16 mg/L, respectively. Under long-term low DO conditions, nitrite oxidizing bacteria (NOB) became a better oxygen competitor than ammonia oxidizing bacteria (AOB) and, as a result, no …

Pump Controller Design For Variable Primary Flow Configuration Systems, Yifan Shi

Durham School of Architectural Engineering and Construction: Dissertations, Theses, and Student Research

Pump systems are utilized widely in Heating, Ventilation and Air-Conditioning (HVAC) systems. There are mainly three configuration types: (1) the constant primary-only flow configuration, (2) the constant primary/variable secondary flow configuration, and (3) the variable primary-only flow configuration. This thesis focuses on finding the optimal control strategy for it and programming a controller for easy in-field usage.

In this thesis, the pump brake horse power (BHP) of the three pump configurations is simulated and compared using varying control methods. The best pump efficiency staging and DP reset control methods are implemented into the pump controller. A one month field experiment …

Vulnerability Of Progressive Collapse In Reinforced Concrete Flat-Plate Buildings, Jinrong Liu

College of Engineering: Graduate Celebration Programs

• Progressive collapse is the spread of initial local failure, causing partial or
  even total collapse of a building.
• Flat plate structure is widely used for office and residential buildings.
• There is a large inventory of older flat plate building without continuous slab bottom reinforcement through columns.
• Limited knowledge exists regarding the risk of disproportionate collapse in
  older flat-plates under sudden column removal during abnormal events.
• Reliable mechanical model is needed for structural evaluation.

Precast Concrete Insulated Wall Panel Corbels Without Thermal Bridging, Mohamed Elkady

Department of Construction Engineering and Management: Dissertations, Theses, and Student Research

The common practice in corbel design is to block out the insulation in order to provide a solid concrete area at the corbel location. This connection practice results in thermal bridging, which significantly reduces the energy performance of the panel. For example, the PCI Design Handbook indicates that the reduction in thermal resistance caused by a solid part with an area equal to 9% of the total panel surface area is as high as 42%. This paper presents a discussion of a new concept for corbel design of insulated wall panels with the thermal break totally preserved. Two different designs …

Parameters Influencing Pressure During Pumping Of Self-Compacting Concrete, Dimitri Feys, Geert De Schutter, Ronny Verhoeven

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Main Difference between Conventional Vibrated Concrete (CVC) and Self-Compacting Concrete (SCC) is Observed in the Fresh State, as SCC Has a Significantly Lower Yield Stress. on the Other Hand, the Placement of SCC by Means of Pumping is Done with the Same Equipment and Following the Same Practical Guidelines Developed for CVC. It Can Be Questioned Whether the Flow Behavior in Pipes of SCC is Different and Whether the Developed Practical Guidelines Can Still Be Applied. This Paper Describes the Results of Full-Scale Pumping Tests Carried Out on Several SCC Mixtures. It Shows Primarily that the Slump or Yield …

Special Section On Natural Treatment Systems: More Than Just A Solution To Pollution, Joel Gerard Burken

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

No abstract provided.

Response Surface Method Based On Radial Basis Functions For Modeling Large-Scale Structures In Model Updating, Linren Zhou, Guirong Yan, Jinping Ou

Civil, Architectural and Environmental Engineering Faculty Research & Creative Works

The Response Surface (RS) Method based on Radial Basis Functions (RBFs) is Proposed to Model the Input-Output System of Large-Scale Structures for Model Updating in This Article. as a Methodology Study, the Complicated Implicit Relationships between the Design Parameters and Response Characteristics of Cable-Stayed Bridges Are Employed in the Construction of an RS. the Key Issues for Application of the Proposed Method Are Discussed, Such as Selecting the Optimal Shape Parameters of RBFs, Generating Samples by using Design of Experiments, and Evaluating the RS Model. the RS Methods based on RBFs of Gaussian, Inverse Quadratic, Multiquadric, and Inverse Multiquadric Are …

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 …

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

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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

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 …

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 …

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.

Performance-Based Engineering Framework For Earthquake And Fire Following Earthquake, Aerik Carlton

Dissertations, Master's Theses and Master's Reports - Open

The objective for this thesis is to outline a Performance-Based Engineering (PBE) framework to address the multiple hazards of Earthquake (EQ) and subsequent Fire Following Earthquake (FFE). Currently, fire codes for the United States are largely empirical and prescriptive in nature. The reliance on prescriptive requirements makes quantifying sustained damage due to fire difficult. Additionally, the empirical standards have resulted from individual member or individual assembly furnace testing, which have been shown to differ greatly from full structural system behavior. The very nature of fire behavior (ignition, growth, suppression, and spread) is fundamentally difficult to quantify due to the inherent …

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 …

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. …

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 …

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 …

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. …

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 …

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 …

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 …