Architectural Engineering Commons^™

Analysis Of The Variability Of Project Cost And Schedule Performance In The Design-Build Environment, Yunping Liang, Baabak Ashuri, Wei Sun

Durham School of Architectural Engineering and Construction: Faculty Publications

Design-build (DB) projects are getting more implementations in the United States. Several studies indicate that the DB project delivery system has advantages in project cost and schedule performance. Despite having comparative advantages, DB projects are found to be far from immune from cost overruns and schedule delay in those studies. It is critical to understand the effects of various factors underpinning the cost and schedule performance of DB projects. The overall objective of this research is to utilize cluster analysis and statistical analysis to identify factors with significant potentials to describe the variability of project cost and schedule performance in …

Option Value Of Contingent Finance Support In Transportation Public-Private Partnership Projects, Yunping Liang, Baabak Ashuri

Durham School of Architectural Engineering and Construction: Faculty Publications

Uncertainties about construction cost and operational revenues are two major risks in transportation public-private partnership (P3) projects. These uncertainties put projects at risk of being unable to fulfill annual debt repayment obligations. When a project generates insufficient cash flow to service the debt in a certain year, it normally has to go for short-term financing by borrowing short-term loans. With the help of revenue risk-sharing mechanisms, supported projects may be able to get rid of unexpected interest disbursement. The objectives of this paper are twofold: (1) evaluate the refinancing cost of P3 highway projects caused by cash flow shortage and …

An Experiential Online Training Approach For Underrepresented Engineering And Technology Students, Arefeh Mohammadi, Kevin Grosskopf, John Killingsworth

Durham School of Architectural Engineering and Construction: Faculty Publications

Workforce pipelines are essential to sustain a productive workforce in an increasingly competitive, high-tech environment. Advanced automation, sensors, materials and data analytics will increase the need for highly skilled workers in the manufacturing (and manufactured construction) sector. Attracting and developing the next-generation workforce is not without its challenges; however, students are often deficient in technical skills and generally have negative perceptions about manufacturing and construction. As a result, new education and training models have been developed to provide instruction at all levels of the educational system, with a focus on both traditional students and non-traditional students, including ethnic minorities, women, …

Mechanical Connection For Concrete Structures, George Morcous, Raed Tawadrous

Durham School of Architectural Engineering and Construction: Faculty Publications

A system and method for connecting precast concrete structures includes anchoring a sleeve within a pocket formed in one of the concrete structures , and placing the concrete structures in contact with one another such that the pocket is diposed around a protruding end of a shear connector embedded in the other concrete structure . A bridge is inserted around the protruding end of the shear connector and a fastener is installed onto the protruding end of the shear connector to engage the bridge and urge the bridge in abutting relation with a lip of the sleeve . The pocket …

Stuck Outdoor Air Damper Faults In Rooftop Units Having Air Economizers: Economic Impact, Fault Symptoms, And Fault Detection And Diagnostics Using Cellular Data Loggers (Cello), Moh'd-Eslam Dahdolan

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

Air economizers are widely used in building air conditioning systems. The purpose of using them is to reduce needed mechanical cooling by properly introducing outdoor air to the space when its temperature is low enough without compromising space ventilation. It is common that air economizer experience malfunction and faulty performance, causing energy savings to be lost, furthermore, energy penalty occur.

This thesis discusses the impacts stuck outdoor air dampers have on the value and performance of air economizers used in air handling units (AHU) and rooftop units (RTU). The study used multiple EnergyPlus simulations of a small office building model …

Workforce Development Through Online Experiential Learning For Stem Education, Arefeh Mohammadi, Kevin Grosskopf, John Killingsworth

Durham School of Architectural Engineering and Construction: Faculty Publications

The U.S. workforce is increasingly comprised of older adults, women, and minorities who lack basic skills and are unable to acquire these skills through traditional educational and training programs. New approaches are needed to provide effective training to the adult learner and flexible support for nontraditional students who must balance work-life demands with limited educational opportunities. Contextualized teaching and learning (CTL) is a form of experiential learning that blends both basic skills and occupational training together in environments that allow students to relate subject matter to real-world situations. Virtual CTL environments can be created to better engage students, provide immediate …

Automated Generation Of Daily Evacuation Paths In 4d Bim, Kyungki Kim, Yong-Cheol Lee

Durham School of Architectural Engineering and Construction: Faculty Publications

Spatial movements of workers and equipment should be carefully planned according to project plans. In particular, it is crucial for workers’ safety to prepare emergency evacuation paths according to changing construction site configurations and construction progress. However, creating evacuation paths for all crews for each day can be an extremely labor-intensive task if it is done manually. Consequently, in most construction projects, evacuation plans are not provided to managers and crews throughout the entire construction. Even state-of-the-art technologies do not suggest ways to generate evacuation paths according to changing progresses presented in 4-Dimensional Building Information Model (4D BIM). This research …

Explorations Of Acoustic Trends In Data Logged In K–12 Classrooms, Kieren Smith

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

The classroom environment influences the ability of children to learn. To ascertain the effect of indoor environment parameters on student achievement, a large-scale project was launched, collecting time-logged data from 220 k-12 classrooms in the eastern Nebraska region for six days each. Data were collected from a variety of disciplines, including acoustics, lighting, indoor air quality, and thermal comfort. This thesis focuses on the acoustic parameters, looking first at how overall classroom values--including average sound levels and room reverberation time--influence student achievement. Using structural equation modeling, the average sound level during times with speech present was discovered to have a …

Efficient Excitation Of Micro/Nano Resonators And Their Higher Order Modes, N. Jaber, M. A. A. Hafiz, S. N. R. Kazmi, M. H. Hasan, F. Alsaleem, S. Ilyas, M. I. Younis

Durham School of Architectural Engineering and Construction: Faculty Publications

We demonstrate a simple and flexible technique to efficiently activate micro/nano-electromechanical systems (MEMS/NEMS) resonators at their fundamental and higher order vibration modes. The method is based on the utilization of the amplified voltage across an inductor, L, of an LC tank resonant circuit to actuate the MEMS/NEMS resonator. By matching the electrical and mechanical resonances, significant amplitude amplification is reported across the resonators terminals. We show experimentally amplitude amplification up to twelve times, which is demonstrated to efficiently excite several vibration modes of a microplate MEMS resonator and the fundamental mode of a NEMS resonator.

Method Of Monitoring Charge Condition Of Heat Pump System, Fadi M. Alsaleem, Gregg M. Hemmelgarn

Durham School of Architectural Engineering and Construction: Faculty Publications

A heat-pump circuit may include an indoor heat exchanger, an outdoor heat exchanger, a compressor adapted to circulate a working fluid between the indoor and outdoor heat exchangers, and an expansion device disposed between the indoor and outdoor heat exchangers. A monitor for the heat-pump system may include a return-air temperature sensor, a supply-air temperature sensor, and a processor. The return-air temperature sensor may be adapted to measure a first air temperature of air upstream of the indoor heat exchanger. The supply-air temperature sensor may be adapted to measure a second air temperature of air down stream of the indoor …

Voltage And Deflection Amplification Via Double Resonance Excitation In A Cantilever Microstructure, Mohammad H. Hasan, Fadi Alsaleem, Abdallah Ramini

Durham School of Architectural Engineering and Construction: Faculty Publications

Cantilever electrostatically-actuated resonators show great promise in sensing and actuating applications. However, the electrostatic actuation suffers from high-voltage actuation requirements and high noise low-amplitude signal-outputs which limit its applications. Here, we introduce a mixed-frequency signal for a cantilever-based resonator that triggers its mechanical and electrical resonances simultaneously, to overcome these limitations. A single linear RLC circuit cannot completely capture the response of the resonator under double resonance excitation. Therefore, we develop a coupled mechanical and electrical mathematical linearized model at different operation frequencies and validate this model experimentally. The double-resonance excitation results in a 21 times amplification of the voltage …

Benchmarking Image Processing Algorithms For Unmanned Aerial System-Assisted Crack Detection In Concrete Structures, Sattar Dorafshan, Robert J. Thomas, Marc Maguire

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper summarizes the results of traditional image processing algorithms for detection of defects in concrete using images taken by Unmanned Aerial Systems (UASs). Such algorithms are useful for improving the accuracy of crack detection during autonomous inspection of bridges and other structures, and they have yet to be compared and evaluated on a dataset of concrete images taken by UAS. The authors created a generic image processing algorithm for crack detection, which included the major steps of filter design, edge detection, image enhancement, and segmentation, designed to uniformly compare dierent edge detectors. Edge detection was carried out by six …

Remotely Testing Whether A Climate Control System Controller Is Correctly Installed, Fadi M. Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

Disclosed are exemplary embodiments of apparatus and methods for remote testing of controllers such as thermostats, to detect incorrect climate control system configuration parameters . In an exemplary embodiment, a computer wirelessly connects with a remote thermostat and sends signal (s) to the thermostat instructing the thermostat to perform climate control function (s) in predefined sequence (s). The computer receives signal (s) from the thermostat indicating whether the thermostat is performing the climate control function (s) in accordance with the sent signal (s). Based on the signal (s) received from the thermostat, the computer determines whether the thermostat is configured …

Need For Aeromedical Evacuation High-Level Containment Transport Guidelines, Shawn G. Gibbs, Jocelyn J. Herstein, Aurora B. Le, Elizabeth L. Beam, Theodore J. Cieslak, James V. Lawler, Joshua L. Santarpia, Terry L. Stentz, Kelli R. Kopocis-Herstein, Chandran Achutan, Gary W. Carter, John J. Lowe

Durham School of Architectural Engineering and Construction: Faculty Publications

Circumstances exist that call for the aeromedical evacuation high-level containment transport (AE-HLCT) of patients with highly hazardous communicable diseases. A small number of organizations maintain AE-HLCT capabilities, and little is publicly available regarding the practices. The time is ripe for the development of standards and consensus guidelines involving AE-HLCT.

Hvac System Remote Monitoring And Diagnosis, Jeffrey N. Arensmeier, Gregg M. Hemmelgarn, Fadi M. Alsaleem, Priotomo Abiprojo

Durham School of Architectural Engineering and Construction: Faculty Publications

A monitoring system for an HVAC system of a building includes a monitoring server located remotely from the building. The monitoring server receives, from a device installed at the building, (i) time-domain current data based on a measured aggregate current supplied to a plurality of components of the HVAC system, and (ii) data based on frequency-domain current data of the measured aggregate current. Based on the received data, the monitoring server accesses (i) whether a failure has occurred in a first com ponent of the plurality of components and (ii) generates a preliminary advisory in response to determining that the …

Strategies And Resources For Government Agencies To Utilize Disadvantaged Business Enterprises In Transportation Design-Build Projects, Baabak Ashuri, Adjo Amekudzi-Kennedy, Stephanie Amoaning-Yankson, Yunping Liang, Yang Cao

Durham School of Architectural Engineering and Construction: Faculty Publications

The Disadvantaged Business Enterprise (DBE) Program was established to provide opportunities for businesses owned and controlled by socially and economically disadvantaged individuals, such as minority-owned and women-owned businesses, to participate in federally funded transportation-related projects. Such DBE participation has increasingly been achieved over the years with the appropriate guidance for traditional project delivery: design-bid-build. However, in recent times the onset of alternative project delivery methods, such as design-build (DB), has introduced challenges for state DOTs trying to implement the DBE program using traditional approaches. This paper presents a synthesis of strategies and resources being used in state DOTs to achieve …

Skip This Chore: Cleaning Your Air Conditioner Condenser Probably Won't Make It Work Better, David Yuill

Durham School of Architectural Engineering and Construction: Faculty Publications

I asked my neighbor who hoses off his air conditioner condenser every spring why he does it. “Because my dad always told me I had to,” he said.

Conventional wisdom like what my neighbor’s dad imparted may always seem right. But through my HVAC scholarship – the study of heating, ventilation and air-conditioning systems – I’ve learned that this particular presumption is probably wrong.

Heat Pump And Air Conditioning Grading Systems And Methods, Fadi Mohammad Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

An expectation module determines an expected average power consumption of a heat pump for a predetermined period as a function of indoor and outdoor temperatures of the building during the predetermined period. A difference module determines a power difference between an average power consumption of the heat pump during the predeter mined period and the expected average power consumption of the heat pump for the predetermined period. A grade determination module determines a grade of the heat pump for the predetermined period based on the power difference of the predetermined period. A reporting module generates a displayable report including the …

Building Envelope And Interior Grading Systems And Methods, Fadi Mohammad Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

A difference module determines differences between an outdoor ambient temperature and an indoor temperature, determines a first average of the differences , and determines a second average of the differences. A storing module stores a first data point, the first data point including the first average and a first total run time of a heating, ventilation, and/or air conditioning (HVAC) system, and stores a second data point, the second data point including the second average and a second total run time of the HVAC system. A fitting module fits a line to the first and second data points. An envelope …

Post-Earthquake Assessment And Numerical Modeling Of Freestanding Heritage Structures, M. Khalid Saifullah, Christine E. Wittich

Department of Civil and Environmental Engineering: Faculty Publications

Historic and heritage structures are particularly vulnerable to earthquakes, where damage or collapse can not only lead to loss of a structure but also the loss of irreplaceable heritage. Many heritage structures can be classified as freestanding (detached) structures, including unreinforced masonry walls, classical multi-drum columns, and statue-pedestal systems. However, the seismic response of freestanding structures (sliding, rocking, rock-slide, overturning) is poorly predicted by existing methods due to geometric non-linearities as well as sensitivity to interface conditions and modeling parameters. Previous studies have focused on analytical modeling of simplified systems and/or experimentation under controlled laboratory conditions. In contrast, this paper …

Experiencing Extreme Height For The First Time: The Influence Of Height, Self-Judgment Of Fear And A Moving Structural Beam On The Heart Rate And Postural Sway During The Quiet Stance, Mahmoud Habibnezhad, Jay Puckett, M. S. Fardhosseini, Houtan Jebelli, Terry Stentz, L. A. Pratama

Durham School of Architectural Engineering and Construction: Faculty Publications

Falling from elevated surfaces is the main cause of death and injury at construction sites. Based on the Bureau of Labor Statistics (BLS) reports, an average of nearly three workers per day suffer fatal injuries from falling. Studies show that postural instability is the foremost cause of this disproportional falling rate. To study what affects the postural stability of construction workers, we conducted a series of experiments in the virtual reality (VR). Twelve healthy adults—all students at the University of Nebraska-Lincoln—were recruited for this study. During each trial, participants’ heart rates and postural sways were measured as the dependent factors. …

Prediction Of Stress Increase At Ultimate In Unbonded Tendons Using Sparse Principal Component Analysis, Eric Mckinney, Minwoo Chang, Marc Maguire, Yan Sun

Durham School of Architectural Engineering and Construction: Faculty Publications

While internal and external unbonded tendons are widely utilized in concrete structures, an analytical solution for the increase in unbonded tendon stress at ultimate strength, ∆f_ps, is challenging due to the lack of bond between strand and concrete. Moreover, most analysis methods do not provide high correlation due to the limited available test data. The aim of this paper is to use advanced statistical techniques to develop a solution to the unbonded strand stress increase problem, which phenomenological models by themselves have done poorly. In this paper, Principal Component Analysis (PCA), and Sparse Principal Component Analysis (SPCA) …

A Practitioner’S Guide To Small Unmanned Aerial Systems For Bridge Inspection, Sattar Dorafshan, Robert J. Thomas, Calvin Coopmans, Marc Maguire

Durham School of Architectural Engineering and Construction: Faculty Publications

Small unmanned aerial system(s) (sUAS) are rapidly emerging as a practical means of performing bridge inspections. Under the right condition, sUAS assisted inspections can be safer, faster, and less costly than manned inspections. Many Departments of Transportation in the United States are in the early stages of adopting this emerging technology. However, definitive guidelines for the selection of equipment for various types of bridge inspections or for the possible challenges during sUAS assisted inspections are absent. Given the large investments of time and capital associated with deploying a sUAS assisted bridge inspection program, a synthesis of authors experiences will be …

Hvac System Air Filter Diagnostics And Monitoring, Priotomo Abiprojo, Fadi M. Alsaleem

Durham School of Architectural Engineering and Construction: Faculty Publications

A system and method for monitoring a heating, ventilation, or air conditioning (HVAC) system of a building is provided. A monitoring server, located remotely from the building, receives operating parameter data from a monitoring device at the building that measures an operating parameter of the HVAC system. The monitoring server generates a plurality of data clusters from the operating parameter data, each data cluster corresponding to operating parameter data generated during steady-state operation of the HVAC system. The monitoring server calculates an average operating parameter value for each data cluster. The monitoring server calculates normalized operating parameter values based on …

Data Driven Approach To Thermal Comfort Model Design, Mostafa Rafaiejokandan

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

Apart from the dominant environmental factors such as relative humidity, radiant, and ambient temperatures, studies have confirmed that thermal comfort significantly depends on internal personal parameters such as metabolic rate, age, and health status. This study reviews the sensitivity of the Predicted Mean Vote (PMV) thermal comfort model relative to its environmental and personal parameters of a group of people in a space. PMV model equations adapted in ASHRAE Standard 55–Thermal Environmental Conditions for Human Occupancy, are used in this investigation to conduct a parametric study by generating and analyzing multi-dimensional comfort zone plots. It has been found that personal …

Evaluation Of Hospital Soundscapes To Improve Patient And Staff Experience, Jay Bliefnick

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

Hospital soundscapes can be difficult environments to assess acoustically due to the continuous activity within units. Routinely, patients perceive these soundscapes poorly when rating their hospital experience on HCAHPS (Hospital Consumer Assessment of Healthcare Providers and Systems) surveys administered after discharge. In addition, hospital staff can be negatively impacted by the acoustical environments in which they work, affecting both performance and job satisfaction. This doctoral research addressed these issues across three phases by collecting acoustical measurements within three individual hospitals, comparing results with provided patient and staff survey information, and conducting laboratory tests of hospital noise perception. In the first …

A Case Study On The Design Of Safe Spaces In Hospitals Vulnerable To Tornadoes In Central Us, Lucy Owusua Ampaw-Asiedu

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

In the wake of recent disasters happening around the world such as the earthquake in Italy (January 2017); hurricanes in the United States (U.S.) (September 2016 and 2017); and compounding disasters in Haiti (September 2010 and 2016); to our best knowledge, never has the world seen the need to work on preemptive rather than reactionary measures to address this issue. Tornadoes are natural hazards that commonly occur in mid-western and central states of the U.S. Tornadoes, like all natural hazards, are very destructive and result in massive destruction to building structures, causing billions of dollars in damage and claim many …

Development Of A Model To Predict The Likelihood Of Complaints Due To Assorted Tone-In-Noise Combinations, Joonhee Lee, Lily M. Wang

Durham School of Architectural Engineering and Construction: Faculty Publications

This paper develops a model to predict if listeners would be likely to complain due to annoyance when exposed to a certain noise signal with a prominent tone, such as those commonly produced by heating, ventilation, and air-conditioning systems. Twenty participants completed digit span tasks while exposed in a controlled lab to noise signals with differing levels of tones, ranging from 125 to 1000 Hz, and overall loudness. After completing the digit span tasks under each noise signal, from which task accuracy and speed of completion were captured, subjects were asked to rate level of annoyance and indicate the likelihood …

Effects Of Reverberation Conditions And Physical Versus Virtual Source Placement On Localization In Virtual Sound Environments, Anna Catton

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

Sound field synthesis systems vary in number and arrangement of loudspeakers and methods used to generate virtual sound environments to study human hearing perception. While previous work has evaluated the accuracy with which these systems physically reproduce room acoustic conditions, less is known on assessing subjective perception of those conditions, such as how well such systems preserve source localization. This work quantifies the accuracy and precision of perceived localization from a multi-channel sound field synthesis system at Boys Town National Research Hospital, which used 24 physical loudspeakers and vector-based amplitude panning to generate sound fields. Short bursts of broadband speech-shaped …

Respirable Dust Monitoring In Construction Sites And Visualization In Building Information Modeling Using Real-Time Sensor Data, Nour Smaoui, Kyungki Kim, Omprakash Gnawali, Young-Joo Lee, Wonho Suh

Durham School of Architectural Engineering and Construction: Faculty Publications

Construction activities, involving cutting, drilling, and grinding of materials, often produce toxic respirable dust that can cause fatal diseases and illnesses. To protect workers from breathing excessive amounts of respirable dust at job sites, superintendents should continuously monitor the level of respirable dust in workspaces and make timely interventions for overexposed workers. However, current practices of respirable dust monitoring have critical drawbacks, and superintendents cannot accurately estimate workers’ exposures to respirable dust or make prompt decisions to protect the workers. Therefore, there is a need for real-time air dust monitoring that can be deployed ubiquitously at a construction site and …