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Browsing by Author "Ozbek, Mehmet, advisor"

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    A framework for evaluating environmental commitment tracking programs in state departments of transportation
    (Colorado State University. Libraries, 2011) Fillion, Andrew Christopher, author; Ozbek, Mehmet, advisor; Clevenger, Caroline, committee member; Taylor, Peter, committee member
    Environmental tracking systems (ETSs) are used by state Departments of Transportation (DOTs) as well as by Federal agencies to track environmental commitments on construction projects from the project development stage through design, construction, and project completion. In this study a framework is developed that any state DOT can use to evaluate existing ETSs implemented by other state DOTs. This framework will allow that state DOT to identify the system that best meets its needs with the ultimate purpose of adopting that system. The framework's main function will be to identify and prioritize the features that a state DOT is looking for in an ETS, to evaluate existing ETSs used by other state DOTs with respect to those features, and to provide a final recommendation on which ETS should be adopted by that state DOT. The developed framework was implemented at the Colorado Department of Transportation (CDOT). The findings and recommendations for that implementation example are also included in this study.
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    An investigation of water quality considerations for premise plumbing systems in buildings
    (Colorado State University. Libraries, 2021) Kalan, Duygu, author; Ozbek, Mehmet, advisor; Omur-Ozbek, Pinar, advisor; Grigg, Neil, committee member; Dooley, Gregory, committee member
    Providing potable and palatable waterq to their consumers is a top priority for drinking water treatment utilities in the US. To ensure the safety of the drinking water, disinfection methods have been applied for over a century. Chlorine is the most extensively used disinfectant to control waterborne pathogen activities. Despite its effectiveness, chlorine is known to react with natural organic matter (NOM) and produce disinfection by-products (DBPs) (e.g., trihalomethanes and haloacetic acids) that are known to be harmful to humans. Currently, DBPs are regulated at the distribution system level. However, premise plumbing systems are unique and different from water distribution systems. Moreover, there are knowledge gaps for premise plumbing in residential and non-residential buildings under routine operations, and that has not been fully understood for different operation scenarios (e.g., use of water-efficient fixtures in conventional buildings) and building types (e.g., green-certified buildings). The primary purpose of this dissertation was to contribute to the body of knowledge on water quality in premise plumbing systems by addressing some of the knowledge gaps identified in the literature. This dissertation comprises three independent but complementary studies. Each study focused on essential aspects of water quality in premise plumbing systems as follows: i) identifying the effects of building type (e.g., conventional vs. green-certified) on water quality in premise plumbing systems, ii) providing a comprehensive literature review on existing contaminant prediction models for premise plumbing systems, and iii) developing a DBP prediction tool for premise plumbing systems. In the first study, effects of building type on premise plumbing water quality were addressed. For this purpose, trihalomethanes (THMs) and water quality parameters, including temperature, pH, free chlorine levels, and total organic carbon (TOC) were collected and compared between a combined conventional and green-certified (i.e., water-efficient) building drinking fountains. Even though the distributed water quality to the green and conventional building sides was the same, statistically significant differences in water quality parameters and TTHMs were observed due to the changes in water chemistry in the premise plumbing systems. The study findings point out the importance of the plumbing pipe age and its impacts on water chemistry. In the second study, a state-of-the-art review was conducted to provide background information on water quality and indoor air quality models that have been implemented in residential and non-residential building premise plumbing systems and indoor air environments. A systematic literature search was conducted in the Compendex, Web of Science, IEEE Explore, Science Direct, and PubMed databases. A total of 22 contaminant prediction modeling studies for premise plumbing and 12 for indoor air quality were reviewed in this study. Among the premise plumbing models, lead and copper prediction models have drawn more attention from researchers than any other contaminants. Due to increased inhalation exposure levels, shower models have been excessively included in risk exposure studies. This review aimed to draw attention to the research needs in modeling approaches, identify the gaps in the literature, and provide a baseline for future research attempts. In the third study, a chloroform prediction model was developed and incorporated into a simulation software to predict chloroform concentrations in a premise plumbing system for eight hours of water stagnation. The model coefficients were determined with the bench-scale experiments based on water quality parameter ranges that can be seen in premise plumbing systems. Chloroform concentrations were tested in a two-story townhouse; experimental and model prediction results were compared. The chloroform prediction model underpredicted chloroform concentrations by 27-37% compared with the house measurements. This study represents an important initial attempt in developing a simulation-based water quality prediction model, which can be implemented in premise plumbing systems. This study contributes to the body of knowledge on water quality in premise plumbing systems by providing a better insight into the effects of conventional and green-certified buildings, shedding light on the current state of numerical modeling research, and implementing a chloroform prediction tool in premise plumbing systems.
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    Impacts and benefits of implementing BIM on bridge and infrastructure projects
    (Colorado State University. Libraries, 2014) Fanning, Blaine, author; Clevenger, Caroline, advisor; Ozbek, Mehmet, advisor; Mahmoud, Hussam, committee member
    To date, BIM (Building Information Modeling) is not widely utilized in infrastructure asset management. Benefits achieved through implementation in vertical construction, however, suggests that BIM represents significant opportunity for gains in process, material and economic efficiency throughout infrastructure project lifecycles. This research documents the current state of BIM implementation across four (4) regional transportation authorities in the United States. Next it provides a detailed case study analyzing and comparing two current (2013) bridge construction projects, one that uses BIM and one that does not. The results are confirmed by the observed reduction in RFIs and CMOs relative to construction area (SF), cost ($), and average daily traffic, compared to typical construction. Finally, it outlines potential benefits and implications of using BIM for infrastructure asset management by regional transportation authorities and the transportation industry in general. Numerous stakeholders involved with horizontal construction and operation currently seek information regarding the potentially significant benefits of integrating BIM into infrastructure asset management. This research is important because its serves to assess and inform such an imminent transition. The specific contribution of this research is to document and assess the role of BIM implementation on one bridge case study in order to highlight the potential of BIM as a dynamic method to assist throughout the lifecycle of infrastructure assets.
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    Involvement of electrical contractors in integrated project delivery (IPD)
    (Colorado State University. Libraries, 2015) Lewis, Fred, author; Ozbek, Mehmet, advisor; Laposa, Steve, committee member; Funk, Loren, committee member
    IPD is believed to be one of the most prominent movements in addressing the inefficiencies inherent in the Architecture Engineering and Construction Industry. However, there is some reluctance in pursing this system, especially by specialized contractors such as electrical contractors. Therefore, the primary goals of this research were to identify issues and risks for ECs to pursue IPD, and provide recommendations to address those issues and risks. The researcher first sought to gain a better understanding of the ECs point of view, and how it could affect their ability to pursue, and ultimately complete IPD projects successfully. This was largely accomplished by conducting interviews with thirteen ECs—six who had experience with IPD and seven who did not have experience with IPD. Overall, the majority of issues/risks expressed by both sets of interviewees were limited to characteristics of the IPD process itself, or the performance of the other team members. Most of the non-experienced ECs wanted prior favorable knowledge of the other IPD team members as a condition for them to participate in an IPD project. However, these same ECs did not possess the favorable qualities they set as a prerequisite for other team members. Therefore, the recommendations to address their issues/risks involve methods to "prepare" the ECs to be successful with IPD. The experienced ECs also expressed issues with BIM and IPD Agreements, which have been addressed in Chapter 5. This report concludes by offering suggestions for future research. These consist of issues/risks the ECs expressed which were outside the scope of this study.
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    Methodology for uncertainty-based inspection planning of concrete bridge decks using mechanistic models of crack formation and propagation
    (Colorado State University. Libraries, 2015) Sanders, Patrick, author; Atadero, Rebecca, advisor; Ozbek, Mehmet, advisor; Senior, Bolivar, committee member
    The bridge inspection program in the United States started in 1971 following the collapse of the Silver Bridge in Ohio. Since then, bridges have generally been inspected every two years. This uniform inspection interval for all bridges is not the most efficient system for conducting inspections because many bridges do not require inspections this frequently, and leads to unnecessary use of inspection resources on bridges that do not require them. Efforts toward changing the bridge inspection program to a risk-based program are being made. Such a program would allow for bridge inspection timing to be based on each particular bridge’s need, and each bridge would then be inspected for the components that present the highest risk to the structure. The research presented herein focuses on using the uncertainty in the current condition of concrete bridge decks to plan inspection timing, and to plan inspection type based on limited resources. A mathematical program called Concrete Deck Cracking Probability Model (CDCPM) is written in MATLAB to model the uncertainty in the occurrence of transverse cracking and delamination in the deck. Through literature review, mechanistic models of the processes that affect cracking are determined and implemented in the program. Using Monte Carlo simulations, the uncertainty in the occurrence of cracking and delamination is analyzed based on the input parameter uncertainty. The effect of different climates and mechanistic models on the prediction of cracking is explored using CDCPM. This model is then applied to a bridge in Larimer County, Colorado to see how the results compare to actual inspection results, and then the model is used to plan a future delamination inspection on the bridge. Another scenario is investigated where CDCPM is used together with uncertainty forecast plots to allocate inspection resources to two bridge decks. CDCPM revealed that the uncertainty in the current bridge condition is heavily influenced by the mechanistic models chosen for the analysis, as well as some of the parameters used in the models. The surface chloride content has a large effect on the delamination of the concrete deck, while the relative humidity and ambient temperature for a given location can affect the probability of transverse cracking. Analysis of the Larimer County bridge inspection reports showed that the model can be good indicator of future damage to the deck. The model provides unique insight into inspection planning using uncertainty. Using the model output along with uncertainty forecast plots of different inspection methods, the inspection manager is provided with a useful planning tool that gives information on the effect of inspection methods on bridge condition assessment. Suggestions for implementing the bridge inspection plan for agency use is also provided.
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    Using expert opinion to quantify accuracy and reliability of nondestructive evaluation on bridges
    (Colorado State University. Libraries, 2013) Hesse, Alex, author; Atadero, Rebecca, advisor; Ozbek, Mehmet, advisor; Chen, Suren, committee member; Nobe, Mary, committee member
    Bridge inspection is an important phase in the bridge management process. In 2009, a joint American Society of Civil Engineers Structural Engineering Institute (ASCE/SEI) and AASHTO Ad-Hoc group was created to identify the issues to guarantee bridge safety and to study how current bridge practices could be improved for the future. This group recommended: "A more rational, risk-based approach to determining the appropriate inspection intervals for bridges is needed, as opposed to a set twenty-four month cycle for all bridges". The committee also recommended a wider use of NDE methods. The difficulty in increasing the use of these NDE methods is the increased costs and time spent using them. One way to deal with this is to implement risk based planning to determine the appropriate inspection frequency, scope, intensity, and methodology. To do this, though, the accuracy, reliability, bias, and cost of each test must be quantified. This study attempts to quantify these parameters for common bridge NDE methods. This was done by two methods. Firstly, a literature review was performed to determine common NDE methods being used and studied for bridge inspection and statistical data was found for these methods. To complement the literature, a four round Delphi method survey was conducted with experts in the NDE bridge field in order to develop a broader range of data that matches real life practices. All of the data was then analyzed and conclusions were drawn to quantify the accuracy, reliability, bias, and various costs incurred for common bridge NDE methods. Based on these results it can be seen that most commonly used bridge NDE methods tend to be under biased and relatively repeatable. It was shown, however, that while inspectors seem to have a pretty good relative understanding of the variability in different tests, they tend to not have as clear of an understanding of the absolute scale of the variability. Furthermore, the accuracy of commonly used bridge NDE methods tends to be relatively variable with the average test measuring a true response between 80% and 85% of the time. Lastly the costs associated with the NDE methods examined here tended to be highly variable making this measure difficult to evaluate. However, by comparing the rankings of each of the four categories that were examined for each NDE method, it is possible to correlate the cost of a method to the bias, accuracy and reliability. This could lead to a more reliable risk-based approach to bridge inspection in the future.