Theses and Dissertations

Permanent URI for this collectionhttps://hdl.handle.net/10217/100391

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Open Access
Comparative life cycle assessment (LCA) and life cycle cost analysis (LCCA) of precast and cast-in-place buildings in United States
(Colorado State University. Libraries, 2020) Vasishta, Tanmay, author; Mehany, Mohammed S. Hashem M., advisor; Killingsworth, John, committee member; Atadero, Rebecca, committee member
Precast construction is one of the growing construction methods for buildings across United States. Many tools have been used to assess environmental and economic impacts of the buildings. LCA and LCCA are one of the most widely used tools to evaluate the environmental and economic impacts of the buildings for their complete life cycle. The research aims to understand the life cycle environment impacts and costs over the complete life cycle for precast and cast-in-place building system. Cradle-to-grave approach was used to develop a framework for assessing the these impacts for precast and cast-in-place building systems constructed in United States through Open LCA software and NIST handbook for LCCA. The environmental impacts and costs associated with the four phases (raw material extraction and manufacturing, installation/construction, operation and demolition) of a precast building in United States were calculated and compared to cast-in-place building system. The research findings implicated that precast using sandwich panel building system had 21% lower life cycle costs (LCC) compared to cast-in-place building system. The construction phase and operation phase also had 38 % and 24% lower LCC compared to cast-in-place building systems. Additionally, lower life cycle environmental impacts towards nine environmental impact indicators were recorded for precast building systems. This study concluded that precast methodology has lower life cycle environmental and economic impacts than cast-in-place and is more sustainable construction method. The developed framework for LCA and LCCA could be applied to all concrete construction projects across the world and could be used as platform for conducting future LCA and LCCA studies as well. The research can also be used by practitioners to understand the phase-wise and total life cycle environmental and economic impacts of precast and further investigate to reduce these impacts.
Open Access
Determining the items that structure bridge management components and their relative weights
(Colorado State University. Libraries, 2012) Johnson, Joshua F., author; Ozbek, Mehmet Egemen, advisor; Clevenger, Caroline, committee member; Atadero, Rebecca, committee member; Chen, Suren, committee member
Ensuring the optimal allocation of available resources between competing bridges is difficult, especially when considering a combination of factors such as continual age related deterioration, ever-increasing traffic demands, and limited resources to address preservation and improvement needs. Optimally allocating funding is crucial since bridges are an essential and expensive component of transportation networks. Bridge Management Systems (BMSs) are commonly used tools that aid managers and decision makers in establishing methods for optimizing available resources and determining how to distribute funds between competing bridges. Recently, NCHRP Synthesis 397 Bridge Management Systems for Transportation Agency Decision Making investigated how transportation agencies are using BMSs and the current state of bridge management practices. The report identified concerns of inadequacy and ineffectiveness with bridge management practices that base decisions solely on single value assessments such as Pontis' Bridge Health Index or the Sufficiency Rating, as found in the federally mandated National Bridge Inspection Standards. Given the critiques in the NCHRP report and other literature related to bridge management, it is evident there exists a need to pursue and develop alternative bridge management practices and systems. The overall purpose of this research is to investigate the concept of isolating the items used to make up a single rating or index in an effort to categorize them under distinct bridge management components such as structural condition, impact on public, and hazard resistance. Each bridge management component has a defined objective as follows: • Structural Condition - accurately access the structural adequacy of a bridge. • Impact on Public - evaluate how bridge attributes affect the traveling public. • Hazard Resistance - evaluate how bridge attributes and external factors affect the vulnerability of a bridge concerning the probability of an extreme event as well as the probability of failure during that event. The specific objectives of this research are (i) to identify the appropriate items that make up each of the aforementioned components and (ii) to determine the relative importance of those items as represented by weighting factors. To achieve these objectives, the researcher conducted a two-part survey seeking input from key bridge management personnel from State DOTs, the Federal Highway Administration (FHWA), and other industry professionals and experts. The first part of the survey identified the appropriate items and the second part determined the relative importance of those items using a mathematical method called the Analytic Hierarchy Process (AHP). The primary contribution of this research is to provide bridge management engineers and decision-makers with effective bridge management components, with well-defined objectives and related items, which clearly identify and distinguish differences in bridge attributes that may go unnoticed when using a single rating or index. This will especially be useful for State DOTs and local agencies, like the Wyoming Department of Transportation, from which the motivation for this research was adapted, who are developing BMSs and methods customized to their particular needs. Upon establishing the bridge management components, by determining the items that make up the components and their relative weights, transportation agencies may utilize them in a variety of ways to conduct multi-criteria decision analyses that complement their current bridge management practices, which in turn may better illustrate the operation of bridges in their system. The total number of respondents was 47, of which 32 were from 29 different State transportation agencies. Of the 47 participants, only 27 contributed to the second part of the survey. A major finding of this research was a result of several participant remarks about with quantifying preservation and maintenance demands through the addition of a fourth bridge management component. The preservation and maintenance component encompasses items that are bridge elements, but may not contribute to the structural capacity of a bridge. Given the degree of influence of adding a fourth component, further research is recommend to confirm these findings and conclusions with a refined two-part survey similar to this research study and possibly interviews or focus groups.
Open Access
Development of a framework to determine the relative weights of contextual factors for complex highway projects
(Colorado State University. Libraries, 2017) Sinha, Akanksha, author; Ozbek, Mehmet E., advisor; Strong, Kelly C., committee member; Atadero, Rebecca, committee member
Traditional project management strategies for highway projects originated with the advent of new construction during the 1950s and 1960s focusing on three dimensions of complexity i.e. cost, schedule and technical (scope). But recently with the major focus shifting towards reconstruction/ rehabilitation projects, the project management strategies also need to shift to include other dimensions rather than perceiving them as risks. A paper by Winter and Smith (2006), "Rethinking Project Management", introduced five new directions to consider while preparing a risk management strategy for complex projects. Following this, a research was conducted by the Second Strategic Highway Research Program, R-10, to study the factors that impact the construction of complex highway projects. The primary outcome of the R-10 study was a five-dimensional approach to project management planning (5DPM) that adds context and financing as two new dimensions to the traditional dimensions of cost, schedule, and technical. Experience during the pilot testing of the 5DPM implementation suggested that the most complicated dimension to assess during the project management planning phase for a complex project is the context dimension which refers to the external factors that have an impact on the project and are difficult to predict and plan for before the start of the project. Currently there is no structured process for evaluating these factors and they are mostly perceived as risks. The R-10 research team identified 8 factor categories which are: stakeholders, project-specific demands, resource availability, environmental, legal and legislative requirements, global and national events, unusual conditions and localized issues and 26 factors under these categories which can cause complexity. The research developed a framework to identify the contextual factors relevant to each specific project and determine the relative weights of these contextual factors using a well-structured approach, the Analytical Hierarchy Process (AHP). Two complex projects within the state of Colorado, U.S. 34 Rebuild and I-25 North Expansion project, were chosen to illustrate the implementation of the developed framework. The primary reason for selecting AHP method was the requirement of pairwise comparison of intangibles derived through the judgement of the experts in a structured mathematical method. The Group AHP was further performed to develop the overall ranking of the contextual factors as a group. The major finding of this study was that as a group, the US 34 Rebuild team valued procedural laws and land acquisition as the most important factor followed by work-zone visualization and marketing and public relations. For the I-25 team, the most important factor was procedural laws followed by limitations and constraints and project management capabilities. The most striking difference between the factor weights for both the projects was that the weights were more evenly distributed between factors for US-34, whereas for I-25, few factors had very high weights while few others had exceptionally low weights. This framework will enable the project management teams of complex highway projects to determine the relevant weights of the factors during the project management planning phase which can help them in making important decisions at the early stages of the project. Through the development of this framework, this study helps transportation agencies identify the contextual factors and prioritize them right from the start in a structured manner rather than perceiving them as risks for their projects.
Open Access
Differences for employees who use BIM/VDC in the construction workplace
(Colorado State University. Libraries, 2014) Inguva, Girija, author; Clevenger, Caroline, advisor; Ozbek, Mehmet, committee member; Atadero, Rebecca, committee member
There is growing recognition across the US construction industry for the benefits of organizational adoption of Building Information Modeling, also referred to as Virtual Design and Construction (BIM/VDC). One of the key factors that enables successful organizational adoption of new technologies is the adoption of these technologies by key participants, in this case by BIM employees. Their positive experiences at their current organization determine their continuation on a BIM/VDC path, thus leading to consistent organizational adoption and negative experiences could mean that they migrate from a BIM career to a Non-BIM career or to another organization to seek better experiences. This research aims to study the perceptions of BIM employees as compared to the perceptions of Non-BIM employees in the construction industry in four key categories: work life balance, career advancement, workplace experience and skill levels. An online survey is used and responses are compared first using averages and then using Pearson's X2 or Fisher's probability test to test for statistical significance where applicable. Differences inform us of the advantages or challenges of a BIM/VDC career at an individual level. Additionally, differences between men and women are also studied, along with differences between BIM employees from organizations with a separate BIM/VDC department and BIM employees from organizations without a separate BIM/VDC department. The general trends observed in terms of averages indicate that BIM/VDC personnel are generally more satisfied with their jobs and consider common barriers to career advancement to be of lesser relevance than their Non-BIM counterparts. The fact that most differences are not statistically different also suggests that BIM employees may not be treated that differently from Non-BIM employees. Of all groups, the most positive perceptions are reported by male BIM respondents from organizations without separate BIM/VDC departments.
Open Access
Life-cycle cost analysis of a bridge in remote mountainous terrain
(Colorado State University. Libraries, 2018) Alnewar, Saurabh, author; Strong, Kelly C., advisor; Senior, Bolivar, committee member; Atadero, Rebecca, committee member
There are various approaches documented and researched to calculate life cycle cost, yet many researchers and applications fail to incorporate user costs to optimize total life cycle costs. To perform a holistic bridge life cycle cost analysis, all the cost components are to be considered. The bridge life cycle cost is divided into: agency cost, user cots and environmental costs. The agency cost comprises of acquisition cost, construction cost, maintenance and repair cost, deck replacement cost and debris removal cost. The user cost constitutes vehicle operation cost (VOC), travel delay costs and crash costs. The environmental costs are out of the scope of the study hence are not calculated. In this study, the impact of user cost on total life cycle cost are calculated for a hypothetical bridge failure in remote mountainous terrain based on two alternative detour routes. The study focuses on using a deterministic approach to calculate total bridge life cycle cost with emphasis on user cost. Detailed mathematical calculations are performed using readily available data on bridge characteristic, agency and user cost components. A sensitivity analysis is performed on two detour route alternatives. The selection of the two detour routes is done based on the availability of possible options around the selected bridge. The results from the user cost calculation for the two detour routes and their impact on total life cycle cost are presented in this study along with the total bridge life cycle cost.
Open Access
The perceived value of using BIM for energy simulation
(Colorado State University. Libraries, 2014) Lewis, Anderson M., author; Valdes-Vasquez, Rodolfo, advisor; Clevenger, Caroline, committee member; Atadero, Rebecca, committee member
Building Information Modeling (BIM) is becoming an increasingly important tool in the Architectural, Engineering & Construction (AEC) industries. Some of the benefits associated with BIM include but are not limited to cost and time savings through greater trade and design coordination, and more accurate estimating take-offs. BIM is a virtual 3D, parametric design software that allows users to store information of a model within and can be used as a communication platform between project stakeholders. Likewise, energy simulation is an integral tool for predicting and optimizing a building's performance during design. Creating energy models and running energy simulations can be a time consuming activity due to the large number of parameters and assumptions that must be addressed to achieve reasonably accurate results. However, leveraging information imbedded within Building Information Models (BIMs) has the potential to increase accuracy and reduce the amount of time required to run energy simulations and can facilitate continuous energy simulations throughout the design process, thus optimizing building performance. Although some literature exists on how design stakeholders perceive the benefits associated with leveraging BIM for energy simulation, little is known about how perceptions associated with leveraging BIM for energy simulation differ between various green design stakeholder user groups. Through an e-survey instrument, this study seeks to determine how perceptions of using BIMs to inform energy simulation differ among distinct design stakeholder groups, which include BIM-only users, energy simulation-only users and BIM and energy simulation users. Additionally, this study seeks to determine what design stakeholders perceive as the main barriers and benefits of implementing BIM-based energy simulation. Results from this study suggest that little to no correlation exists between green design stakeholders' perceptions of the value associated with using information from BIMs to inform energy simulation and their engagement level with BIM and/or energy simulation. However, green design stakeholder perceptions of the value associated with using information from BIMs to inform energy simulation and their engagement with BIM and/or energy simulation may differ between different user groups (i.e. BIM users only, energy simulation users only, and BIM and energy simulation users). For example, the BIM-only user groups appeared to have a strong positive correlation between the perceptions of the value associated with using information from BIMs to inform energy simulation and their engagement with BIM. Additionally, this study suggests that the top perceived benefits of using BIMs to inform energy simulations among green design stakeholders are: facilitation of communication, reducing of process related costs, and giving users the ability examine more design options. The main perceived barrier of using BIMs to inform energy simulations among green design stakeholders was a lack of BIM standards for model integration with multidisciplinary teams. Results from this study will help readers understand how to better implement BIM-based energy simulation while mitigating barriers and optimizing benefits. Additionally, examining discrepancies between user groups can lead the identification and improvement of shortfalls in current BIM-based energy simulation processes. Understanding how perceptions and engagement levels differ among different software user groups will help in developing a strategies for implementing BIM-based energy simulation that are tailored to each specific user group.

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Browsing Theses and Dissertations by Author "Atadero, Rebecca, committee member"