Matching Items (176)
Description
Concrete design has recently seen a shift in focus from prescriptive specifications to performance based specifications with increasing demands for sustainable products. Fiber reinforced composites (FRC) provides unique properties to a material that is very weak under tensile loads. The addition of fibers to a concrete mix provides additional ductility and reduces the propagation of cracks in the concrete structure. It is the fibers that bridge the crack and dissipate the incurred strain energy in the form of a fiber-pullout mechanism. The addition of fibers plays an important role in tunnel lining systems and in reducing shrinkage cracking in high performance concretes. The interest in most design situations is the load where cracking first takes place. Typically the post crack response will exhibit either a load bearing increase as deflection continues, or a load bearing decrease as deflection continues. These behaviors are referred to as strain hardening and strain softening respectively. A strain softening or hardening response is used to model the behavior of different types of fiber reinforced concrete and simulate the experimental flexural response. Closed form equations for moment-curvature response of rectangular beams under four and three point loading in conjunction with crack localization rules are utilized. As a result, the stress distribution that considers a shifting neutral axis can be simulated which provides a more accurate representation of the residual strength of the fiber cement composites. The use of typical residual strength parameters by standards organizations ASTM, JCI and RILEM are examined to be incorrect in their linear elastic assumption of FRC behavior. Finite element models were implemented to study the effects and simulate the load defection response of fiber reinforced shotcrete round discrete panels (RDP's) tested in accordance with ASTM C-1550. The back-calculated material properties from the flexural tests were used as a basis for the FEM material models. Further development of FEM beams were also used to provide additional comparisons in residual strengths of early age samples. A correlation between the RDP and flexural beam test was generated based a relationship between normalized toughness with respect to the newly generated crack surfaces. A set of design equations are proposed using a residual strength correction factor generated by the model and produce the design moment based on specified concrete slab geometry.
ContributorsBarsby, Christopher (Author) / Mobasher, Barzin (Thesis advisor) / Rajan, Subramaniam D. (Committee member) / Neithalath, Narayanan (Committee member) / Arizona State University (Publisher)
Created2011
Description
Current information on successful leadership and management practices is contradictory and inconsistent, which makes difficult to understand what successful business practices are and what are not. The purpose of this study is to identify a simple process that quickly and logically identifies consistent and inconsistent leadership and management criteria. The hypothesis proposed is that Information Measurement Theory (IMT) along with the Kashiwagi Solution Model (KSM) is a methodology than can differentiate between accurate and inaccurate principles the initial part of the study about authors in these areas show how information is conflictive, and also served to establish an initial baseline of recommended practices aligned with IMT. The one author that excels in comparison to the rest suits the "Initial Baseline Matrix from Deming" which composes the first model. The second model is denominated the "Full Extended KSM-Matrix" composed of all the LS characteristics found among all authors and IMT. Both models were tested-out for accuracy. The second part of the study was directed to evaluate the perception of individuals on these principles. Two different groups were evaluated, one group of people that had prior training and knowledge of IMT; another group of people without any knowledge of IMT. The results of the survey showed more confusion in the group of people without knowledge to IMT and improved consistency and less variation in the group of people with knowledge in IMT. The third part of the study, the analysis of case studies of success and failure, identified principles as contributors, and categorized them into LS/type "A" characteristics and RS/type "C" characteristics, by applying the KSM. The results validated the initial proposal and led to the conclusion that practices that fall into the LS side of the KSM will lead to success, while practices that fall into the RS of the KSM will lead to failure. The comparison and testing of both models indicated a dominant support of the IMT concepts as contributors to success; while the KSM model has a higher accuracy of prediction.
ContributorsReynolds, Harry (Author) / Kashiwagi, Dean (Thesis advisor) / Sullivan, Kenneth (Committee member) / Badger, William (Committee member) / Arizona State University (Publisher)
Created2011
Description
Ultra-concealable multi-threat body armor used by law-enforcement is a multi-purpose armor that protects against attacks from knife, spikes, and small caliber rounds. The design of this type of armor involves fiber-resin composite materials that are flexible, light, are not unduly affected by environmental conditions, and perform as required. The National Institute of Justice (NIJ) characterizes this type of armor as low-level protection armor. NIJ also specifies the geometry of the knife and spike as well as the strike energy levels required for this level of protection. The biggest challenges are to design a thin, lightweight and ultra-concealable armor that can be worn under street clothes. In this study, several fundamental tasks involved in the design of such armor are addressed. First, the roles of design of experiments and regression analysis in experimental testing and finite element analysis are presented. Second, off-the-shelf materials available from international material manufacturers are characterized via laboratory experiments. Third, the calibration process required for a constitutive model is explained through the use of experimental data and computer software. Various material models in LS-DYNA for use in the finite element model are discussed. Numerical results are generated via finite element simulations and are compared against experimental data thus establishing the foundation for optimizing the design.
ContributorsVokshi, Erblina (Author) / Rajan, Subramaniam D. (Thesis advisor) / Neithalath, Narayanan (Committee member) / Mobasher, Barzin (Committee member) / Arizona State University (Publisher)
Created2012
Description
The current method of measuring thermal conductivity requires flat plates. For most common civil engineering materials, creating or extracting such samples is difficult. A prototype thermal conductivity experiment had been developed at Arizona State University (ASU) to test cylindrical specimens but proved difficult for repeated testing. In this study, enhancements to both testing methods were made. Additionally, test results of cylindrical testing were correlated with the results from identical materials tested by the Guarded Hot&ndashPlate; method, which uses flat plate specimens. In validating the enhancements made to the Guarded Hot&ndashPlate; and Cylindrical Specimen methods, 23 tests were ran on five different materials. The percent difference shown for the Guarded Hot&ndashPlate; method was less than 1%. This gives strong evidence that the enhanced Guarded Hot-Plate apparatus in itself is now more accurate for measuring thermal conductivity. The correlation between the thermal conductivity values of the Guarded Hot&ndashPlate; to those of the enhanced Cylindrical Specimen method was excellent. The conventional concrete mixture, due to much higher thermal conductivity values compared to the other mixtures, yielded a P&ndashvalue; of 0.600 which provided confidence in the performance of the enhanced Cylindrical Specimen Apparatus. Several recommendations were made for the future implementation of both test methods. The work in this study fulfills the research community and industry desire for a more streamlined, cost effective, and inexpensive means to determine the thermal conductivity of various civil engineering materials.
ContributorsMorris, Derek (Author) / Kaloush, Kamil (Thesis advisor) / Mobasher, Barzin (Committee member) / Phelan, Patrick E (Committee member) / Arizona State University (Publisher)
Created2011
Description
This dissertation examines an analytical methodology that considers predictive maintenance on industrial facilities equipment to exceed world class availability standards with greater understanding for organizational participation impacts. The research for this study was performed at one of the world's largest semiconductor facilities, with the intent of understanding one possible cause for a noticeable behavior in technical work routines. Semiconductor manufacturing disruption poses significant potential revenue loss on a scale easily quantified in millions of dollars per hour. These instances are commonly referred to as "Interruption to production" (ITP). ITP is a standardized metric used across Company ABC's worldwide factory network to track frequency of occurrence and duration of manufacturing downtime. ITP, the key quantifiable indicator in this dissertation, will be the primary analytical measurement to identify the effectiveness of maintenance personnel's work routines as they relate to unscheduled downtime with facilities systems. This dissertation examines the process used to obtain change in an industrial facilities organization and the associated reactions of individual organizational members. To give the reader background orientation on the methodology for testing, measuring and ultimately assessing the benefits and risks associated with integrating a predictive equipment failure methodology, this dissertation will examine analytical findings associated with the statement of purpose as it pertains to ITP reduction. However, the focus will be the exploration of behavioral findings within the organization and the development of an improved industry standard for predictive ITP reduction process implementation. Specifically, findings associated with organizational participation and learning development trends found within the work group.
ContributorsMcDonald, Douglas Kirk (Author) / Sullivan, Kenneth (Thesis advisor) / Badger, William (Committee member) / Verdini, William (Committee member) / Arizona State University (Publisher)
Created2012
Description
Calcium hydroxide carbonation processes were studied to investigate the potential for abiotic soil improvement. Different mixtures of common soil constituents such as sand, clay, and granite were mixed with a calcium hydroxide slurry and carbonated at approximately 860 psi. While the carbonation was successful and calcite formation was strong on sample exteriors, a 4 mm passivating boundary layer effect was observed, impeding the carbonation process at the center. XRD analysis was used to characterize the extent of carbonation, indicating extremely poor carbonation and therefore CO2 penetration inside the visible boundary. The depth of the passivating layer was found to be independent of both time and choice of aggregate. Less than adequate strength was developed in carbonated trials due to formation of small, weakly-connected crystals, shown with SEM analysis. Additional research, especially in situ analysis with thermogravimetric analysis would be useful to determine the causation of poor carbonation performance. This technology has great potential to substitute for certain Portland cement applications if these issues can be addressed.
ContributorsHermens, Stephen Edward (Author) / Bearat, Hamdallah (Thesis director) / Dai, Lenore (Committee member) / Mobasher, Barzin (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
Description
The Information Measurement Theory (IMT) is a revolutionary thinking paradigm. Its principles allow an individual to accurately perceive reality and simplify the complexities of life. To understand IMT, individuals start by first recognizing that everything must follow natural law and cause and effect, that there is no randomness, and that everyone changes at a certain rate. They then move on to understanding that individuals are described by certain characteristics that can be used to predict their future behavior. And finally, they discover that they must learn to understand, accept, and improve themselves while understanding and accepting others. The author, who has spent a considerable amount of time studying and utilizing IMT, believes that IMT can be used within the field of psychology. The extraordinary results that IMT has produced in the construction industry can potentially be produced in a similar fashion within the psychology field. One of the most important principles of IMT teaches that control or influence over others does not exist. This principle alone differentiates IMT from the traditional model of psychology, which is dedicated to changing an individual (through influence). Five case studies will be presented in which individuals have used the principles of IMT to overcome severe issues such as substance abuse and depression. Each case study is unique and exhibits a remarkable change within each individual.
ContributorsMalladi, Basavanth (Author) / Kashiwagi, Dean (Thesis director) / Sullivan, Kenneth (Committee member) / Kashiwagi, Jacob (Committee member) / Barrett, The Honors College (Contributor) / Department of Psychology (Contributor)
Created2014-05
Description
Abstract As we move forward in education reform in the globalized 21st century, the United States must visit new ways to teach science in high school classrooms. The goal of this investigation is to analyze the current research literature for the best and most promising teaching strategies and techniques in secondary education biology classrooms that promote academic excellence for all students. Looking at policy and school reform literature in science education to establish the context of the current system, the paper will not focus on the political as or systematic changes needed to ground an overall successful system. However, because of their inherent effect on the education system, the political aspects of education reform will be briefly addressed. The primary focus, by addressing the emphasis on standardization, inflexibility of instruction and lack of creativity specifically in high school biology classrooms, seeks to clarify small changes that can influence students' academic outcomes. The United States is performing on such a poor level in science and math proficiency that it cannot match students abroad and this is seen through test scores and the production of competent graduates. This investigation serves to organize literature from education researchers and showcase best and promising teaching and learning practices that catalyze academic excellence for all students in our pluralistic, democratic and complex schooling and societal contexts.
ContributorsHildebrandt, Kevin Andrew (Author) / Ovando, Carlos (Thesis director) / Schugurensky, Daniel, 1958- (Committee member) / Fischman, Gustavo (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of International Letters and Cultures (Contributor)
Created2013-05
Description
As green buildings become more popular, the challenge of structural engineer is to move beyond simply green to develop sustainable, and high-performing buildings that are more than just environmentally friendly. For decades, Portland cement-based products have been known as the most commonly used construction materials in the world, and as a result, cement production is a significant source of global carbon dioxide (CO2) emissions, and environmental impacts at all stages of the process. In recent years, the increasing cost of energy and resource supplies, and concerns related to greenhouse gas emissions and environmental impacts have ignited more interests in utilizing waste and by-product materials as the primary ingredient to replace ordinary Portland cement in concrete systems. The environmental benefits of cement replacement are enormous, including the diversion of non-recycled waste from landfills for useful applications, the reduction in non-renewable energy consumption for cement production, and the corresponding emission of greenhouse gases. In the vast available body of literature, concretes consisting activated fly ash or slag as the binder have been shown to have high compressive strengths, and resistance to fire and chemical attack. This research focuses to utilize fly ash, by-product of coal fired power plant along with different alkaline solutions to form a final product with comparable properties to or superior than those of ordinary Portland cement concrete. Fly ash mortars using different concentration of sodium hydroxide and waterglass were dry and moist cured at different temperatures prior subjecting to uniaxial compressive loading condition. Since moist curing continuously supplies water for the hydration process of activated fly ash mortars while preventing thermal shrinkage and cracking, the samples were more durable and demonstrated a noticeably higher compressive strength. The influence of the concentration of the activating agent (4, or 8 M sodium hydroxide solution), and activator-to-binder ratio of 0.40 on the compressive strengths of concretes containing Class F fly ash as the sole binder is analyzed. Furthermore, liquid sodium silicate (waterglass) with silica modulus of 1.0 and 2.0 along with activator-to-binder ratio of 0.04 and 0.07 was also studied to understand its performance in contributing to the strength development of the activated fly ash concrete. Statistical analysis of the compressive strength results show that the available alkali concentration has a larger influence on the compressive strengths of activated concretes made using fly ash than the influence of curing parameters (elevated temperatures, condition, and duration).
ContributorsBanh, Kingsten Chi (Author) / Neithalath, Narayanan (Thesis director) / Rajan, Subramaniam (Committee member) / Mobasher, Barzin (Committee member) / Civil, Environmental and Sustainable Engineering Programs (Contributor) / Barrett, The Honors College (Contributor)
Created2013-05
Description
The purpose of this research is to gain a deeper understanding of the often-despised financial sector while exploring the parallels it reflects in our society. Information Measurement Theory was applied to several aspects of life apparent in both the financial sector and our society in order to discover parallels present in both. By analyzing the financial sector against our society as a whole, it becomes apparent that the financial sector's composition of individuals reflects that of our societies and is a close representation. Further, the financial sector is able to reflect the importance of information and how individuals react to and justify good and bad results from decision-making. In all our despise of the financial sector is nothing more than the loathe of inherent flaws in our society as a whole.
ContributorsHappe, John Nicholas (Author) / Kashiwagi, Dean (Thesis director) / Sullivan, Kenneth (Committee member) / Barlish, Kristen (Committee member) / Barrett, The Honors College (Contributor) / Department of Finance (Contributor) / Sandra Day O'Connor College of Law (Contributor) / Department of Psychology (Contributor)
Created2013-05