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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
41

Using Building Information Modeling (BIM) and the Last Planner System (LPS) to Reduce Construction Process Delay

AI Hussein, Zaid K 01 October 2016 (has links)
The construction industry suffers from many practical problems and challenges; most being related to construction management. One of the most common recurring problems in construction projects is delay. Delay is a primary factor that can have an effect on project duration, scheduled delivery date, as well as the overhead cost of the project. This study investigated the problem of delays in construction projects. The research focused on the combination of Building Information Modeling (BIM) and Last Planner System (LPS) together to measure the execution time of construction projects. The aim of this study was to determine whether using BIM and LPS together affect construction process delay differently than using BIM or LPS alone. The methodology of this study relied on data collection through administration of survey questionnaires to key players and participants at construction companies. Interviews were conducted with construction experts from four construction companies that used BIM and LPS individually in their system as case studies to verify and validate the findings. The outcomes of this survey will be helpful to construction practitioners to reduce delay in construction operations and to shorten projects duration.
42

Mechanical Properties of Inconel 718 Processed Using Electron Beam Free Form Fabrication (EBF<sup>3</sup>)

Waters, Brent R. 01 March 2018 (has links)
Electron beam freeform fabrication (EBF3) is a rapid metal deposition process that works efficiently with the wieldable alloy Inconel 718 (IN 718). EBF3 is a developing additive manufacturing (AM) process that can manufacture IN 718 parts directly from computer aided design (CAD) data. EBF3 can produce parts significantly faster and more energy efficient than competing IN 718 AM technologies. The EBF3 process utilizes metal wire feedstock which is induced into a molten pool using a focused electron beam in a vacuum environment. This allows parts to be built layer by layer, creating intricate shapes that can be produced cheaper and faster than traditionally manufactured IN 718 parts. Furthermore, it allows traditionally manufactured parts to be modified as additional form is added to them using EBF3. Multiple industries rely on IN 718 parts and can utilize this technology including aerospace engineering, oil refinery, nuclear power generation, and food processing.A main drawback of EBF3 is the lack of knowledge of the effect different EBF3 build techniques will have on the properties of the deposited materials. Most of the reliable data on the mechanical properties relate to a linear build-up strategy and focus on the mechanical properties in the deposition direction (DD). There is no data related to other build-up techniques such as rotation build-up or transitional builds from forged material to EBF3 material. Reliable data on the behavior and microstructure of EBF3 material in a direction other than the DD is also difficult to find. Previous studies showed build-up height influenced mechanical properties but its role is not fully understood yet. This paper presents the mechanical properties and microstructure of an IN 718 plate built using a EBF3 rotational build-up strategy through utilizing a forged plug in the center. The tensile properties of samples at the transition from forged to EBF3 material showed higher ductility and reduced strength than pure EBF3 material. This is likely due the influence of the forge material in one half of the specimen. Samples taken at approximately 15 degree increments from 0 to 90 degrees rotation to the DD in the additive portion of the plate were subjected to tensile testing. Along the build height, or the transverse direction (TD), the lowest strength was demonstrated and the TD aligned strongly to a <001> texture. Samples 45 degrees to the DD showed the greatest strength due to their preference for aligning to a <111> texture. Samples low on the build height demonstrated a higher strength than those on the top and displayed grain structures along the TD which were long, linear, and narrow across multiple deposition layers.
43

Current State of Practice Associated with the Use of Building Information Modeling (BIM) in the Custom Home Building Industry

Smith, William Noble 01 December 2017 (has links)
Building Information Modeling (BIM) has entered the construction industry and has permeated the commercial sector. Research is continually performed to expand the capabilities and applications within the industry. However, research has historically been mostly limited to the commercial sector and has seen little expansion to other sectors of the industry including the residential sector. The potential cause for this may be the limited number of industry professionals who utilize the software to the benefit of their companies. The focus of this study was specifically the custom home building sector of residential construction in the United States because of the unique and potentially complex nature of each project. The study was performed using a Delphi Panel, which utilizes a panel of experts to reach a consensus on a given subject. In this study, the goal was to reach a consensus on the most common uses challenges and benefits of BIM within the residential sector. In the first questionnaires, the experts were asked to identify, with a series of demographic questions including the number of employees in their company, the number of homes they build each year, and the average sale price of each home. Each expert's responses to the demographic questions were cross-referenced with the responses concerning uses, benefits, and challenges to provide other industry members wishing to implement with relatable demographic references to compare with their own company demographics. The experts then identified how they used BIM, what benefits they had seen, and any challenges they faced. The uses, benefits, and challenges identified in this questionnaire were ranked in the following questionnaire to identify the most common uses, greatest benefits, and greatest challenges.The top uses identified by this expert panel were design and visualization, the creation of construction documents, and quantity take-offs. The most common benefits identified by this panel were client visualization, plan accuracy, improved client communication, and ease of plan revisions. The most common challenges identified by this panel were high software costs, the steep learning curve when training employees, and the time-consuming nature of creating and maintain models correctly.
44

An Investigation of Employee Satisfaction and Employee Empowerment Specific to On-Site Supervisors in the Residential Construction Industry

Halvorsen, David Lars 01 December 2005 (has links)
Employee satisfaction and empowerment are vital elements to businesses in most industries. The construction industry has various types of employees, ranging from managers and executives to on-site supervisors and laborers. This study was conducted to obtain a greater understanding about the elements and levels of satisfaction and empowerment of on-site supervisors in the residential construction industry. An on-site supervisor in the residential construction industry is responsible for coordinating and managing employees, materials, equipment, budgets, schedules, contracts, and the safety of employees and the general public. They are also the employees most frequently perceived as accountable for the success or failure of any project. Following a thorough review of the related literature, a questionnaire was developed to determine the levels of satisfaction and empowerment of on-site supervisors. This questionnaire was distributed by e-mail to on-site supervisors of companies on Professional Builders top 400 list for 2005. A total of 122 on-site supervisors completed the survey. Statistical tools, including Pearson's product-moment correlation and coefficient of determination, were utilized to analyze the gathered data that identified the satisfaction and empowerment levels of on-site supervisors. It was discovered that a statistically significant correlation existed between satisfaction and empowerment. In addition, descriptive statistics were used to create lists of major elements leading to employee satisfaction and empowerment.
45

Current Practices of Experiential Learning in the United States Construction and Technology Programs

Abdelaty, Ahmed, Shrestha, Joseph 20 May 2019 (has links) (PDF)
Construction education is dynamic and practice oriented. As such, effective construction programs require significant collaboration with the construction industry. This collaboration, in the form of internship or cooperative programs, increase the student readiness for the job market by providing valuable field experience. Construction programs in the United States (US) established several internship requirements that range from being optional to multiple required internships. This study focuses on scanning the current internship requirements set by construction and engineering technology programs in the US by gathering information including; 1) Number and length of required internships, 2) Internship prerequisites, 3) Internship deliverables, 4) assessment method. The outcome of this study is expected to help construction programs improve their internship or cooperative requirements by considering the prevailing practices developed by other schools. Additionally, the study provides recommendations to enhance the effectiveness of internship for positive experiential learning.
46

Critical Analysis of Current Practices of Highway Construction Cost Index (HCCI) Calculation and Utilization

Shrestha, Joseph, Jeong, H. David, Gransberg, Douglas D. 01 January 2016 (has links)
A proper understanding of the local construction market is essential for making appropriate project budgeting and planning decisions. State highway agencies typically use highway construction cost indexes (HCCIs) to understand the current market conditions. In the U.S. highway construction industry, the Federal Highway Administration (FHWA) pioneered the concept of a HCCI as an indicator of the national construction market. State Departments of Transportation (DOT) also started developing their state level HCCIs to better represent their state level construction markets. But, some state DOTs noted the lack of guidance to develop and update their HCCIs. This paper summarizes literature review and nationwide questionnaire survey results to identify the current practices of calculating and using HCCIs. There are two methods to generate basket of construction items for HCCI calculation: a) categorized market basket and b) item level market basket. The Fisher index is the most popular indexing formula among the state DOTs and is also recommended by the FHWA and International Monetary Fund (IMF). Despite many potential users of HCCIs, the current use of HCCIs is very limited in state DOTs.
47

An Exploratory Look at Thefts from Construction Sites

Shrestha, Joseph, Osborne, Dustin Lee 10 April 2019 (has links)
Theft of construction equipment, materials, and tools from construction sites results in approximately one billion dollars in direct annual losses to the U.S. construction industry per year. A better understanding of theft characteristics is vital to reducing this figure. This study analyzes over 15,000 incidents from the National Incident-Based Reporting System (NIBRS) to understand characteristics such as theft prevalence, average monetary losses, and recovery rates. The study finds that contractors lost an average of about $6,000 per incident. Trucks are the most expensive theft targets, with an average loss of about $42,000 per incident, and also the most likely item to be recovered (55% of the time). However, recovery rate across all targets was less than 7%. The results of this study provide the most accurate and extensive statistics to date on construction theft characteristics. The study also identifies best practices to reduce thefts such as the use of survellience systems. Further, the use of advanced marking and tracking systems to safeguard expensive equipment and vehicles and aid their recoveries are discussed. The findings are expected to aid contractors and law enforcement agencies in formulating methods for reducing thefts of construction items and improving the likelihood of their recoveries.
48

ASSESSING THE APPLICATION OF THE UNMANNED AERIAL SYSTEMS (UAS) IN EARTHWORK VOLUME MEASUREMENT

Wang, Xi 01 January 2018 (has links)
Earthwork operations are often one of the major cost items on infrastructure construction projects. Because earthwork is largely influenced by unstable construction conditions and organization plans, it becomes the emphasis and difficulties of the cost control in the construction process. Therefore, precise estimates of actual earthwork volumes are important for both owners and contractors alike to ensure appropriate payments are made. However, measuring work on site requires lots of time and labors because of various and irregular site conditions. Conventional measurement methods, such as planned quantities from the drawings or estimates from equipment activity, are rough estimates with significant opportunities for errors and safety concerns. Recently, unmanned aerial systems (UAS) have become popular for numerous surveying applications in civil engineering. They require less cost and time consumptions compared with traditionally manual methods. Also, they are able to perform photogrammetric data acquisition with equipped digital cameras in hazardous, complex or other conditions that may present high safety risks. However, UAS photogrammetry for research applications is still in its infancy, especially in construction management, and research conducted on UAS photogrammetry for earthwork volume estimation are very limited. Therefore, this research intends to investigate and validate the feasibility and efficiency of utilizing the UAS photogrammetry surveying technique to estimate earthwork volume. The research is conducted into three steps based on distinct case studies: firstly, adapting a basic analysis through a case study to preliminarily prove the effectiveness of the UAS photogrammetry method in earthwork volume measurement; also providing an analytical foundation for further utilizations; secondly, Quantitatively assessing the impact of flight parameters and environmental factors on the accuracy of UAS photogrammetry in earthwork volume measurement and identifying the most influential individual or combinations through observations and a statistical multiple regression analysis; at last, comparing volumes calculated by using the UAS platform and other two conventional methods which are Average-End-Area method and grid method in AutoCAD to further validate the feasibility of using the UAS technology in the process of earthwork volumes estimation. The results indicate that the UAS is an effective method for earthwork volume measurement. According to published standards, practice experience, and literature, the measurement errors are in an acceptable range when parameters are under control. In addition, the UAS demonstrates its advantages in balancing between the accuracy and efficiency compared with conventional earthwork volume measurement methods.
49

HAZARD RECOGNITION AND RISK PERCEPTION AMONG UNION ELECTRICIANS

Jazayeri, Elyas 01 January 2019 (has links)
Hazard recognition and risk perception are two important factors that are a focus of most safety training programs. According to previous research, unrecognized hazards could lead to underestimation of risks, which ultimately could lead to injuries and fatalities. The primary objective of this research was to assess hazard recognition and safety risk perception skills in the electrician trade among electricians in unions. Another goal of this study was to find possible correlation between level of engagement in safety training and hazard recognition and risk perception skills. The research objectives were accomplished by gathering data from sixty-seven apprentices and journeymen across the United States. Each individual was asked to find identify hazards and to assess the risk associated with each hazard. both groups of apprentices and journeymen are similar to each other in terms of hazard recognition and both are significantly different than an expert group.The result also shows that apprentices perceive the risk not significantly different than the expert group. The result will help understand the impact of the level of engagement of safety training on hazard recognition and risk perception skills of their workers. The result could also help electrical unions identify performance gaps in their training and ultimately improve safety behaviors with union electricians.
50

Stormwater Best Management Practices: Improvement and Evaluation

Pilon, Brent Steven 01 December 2010 (has links)
Each of the studies conducted herein is related to best management practices for stormwater pollutant removal. This thesis is divided into two chapters. Chapter One details the development and functionality of a novel stormwater detention pond outlet, the solid state skimmer. The device is a perforated riser having no moving parts that is capable of draining detention ponds primarily from the topmost orifices. We found that such a device is capable of reducing effluent turbidity and sediment concentrations compared to a traditional riser outlet. Chapter Two describes a water quality monitoring study performed to show that a pervious concrete detention system can remove stormwater pollutants from parking lot runoff. The stormwater flowed across asphalt paving before infiltrating into the pervious concrete and an aggregate sub-base below. We sampled the runoff before it entered the pervious and after it passed through the detention system and found significant decreases in several pollutants.

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