Zeiada W.A.,University of Sharjah |
Kaloush K.E.,Civil |
Underwood B.S.,Arizona State University |
Transportation Research Record | Year: 2016
Various laboratory testing methods have been developed to characterize the fatigue response of asphalt concrete mixtures. These test methods attempt to simulate in-service conditions or formulate constitutive models. Experiments such as the four-point beam fatigue test have attempted to simulate in-service conditions. The prediction accuracy of such experiments depends on their effectiveness in simulating actual field conditions such as loading, support, stress state, and environment. Constitutive modeling experiments have aimed at measuring fundamental stress-strain relationships so that rigorous constitutive models can be formulated. The results from these experiments are used as input for field performance prediction algorithms. The uniaxial fatigue test is a promising method in this category because of the constant stress state across the specimen section. A few documents have focused on standard test methods for the uniaxial fatigue test; however, there are no AASHTO or ASTM protocols available that include the healing of asphalt concrete mixtures. The main objective of this study was to report on the development of a uniaxial fatigue test protocol that measures fatigue damage and healing of asphalt concrete mixtures. The documented work includes surrogate studies to identify appropriate sample fabrication procedures, gluing materials and procedures, alignment, machine compliance, type of strain wave shape, and strain-control mode of loading. It was found that the use of a gluing jig and 180-mm compaction height was essential to achieve successful mid-specimen failures. In addition, the sinusoidal strain wave shape and on-specimen strain-controlled mode of loading are appropriate test conditions for fatigue damage and healing characterization of asphalt concrete mixtures. © 2016, National Research Council. All rights reserved.
Gheni A.A.,Missouri University of Science and Technology |
ElGawady M.A.,Civil |
ElGawady M.A.,American Concrete Institute |
ACI Materials Journal | Year: 2017
An experimental investigation was conducted to investigate the effects of replacing varying percentages of fine natural aggregates with crumb rubber in concrete masonry units (CMUs), creating rubberized concrete masonry units (RCMUs). The mechanical and physical characteristics of RCMUs having 0, 10, 20, and 37% crumb rubber were investigated and presented in this paper. The unit weight and water absorption of RCMUs were measured. A scanning electron microscope (SEM) analysis was used to study the global structure for RCMUs and the interfacial zone. RCMUs were also exposed to extreme weather conditions for 72 days inside an environmental chamber. Furthermore, RCMUs were subjected to rapid freezing-and-thawing tests. The RCMUs, as well as grouted and ungrouted masonry prisms, were tested under monotonic and cyclic axial loads. The results indicated that RCMUs with high rubber content displayed higher values of axial ultimate strains. RCMUs exhibited a significant strain softening while, conversely, failure was quite brittle in CMUs. RCMU specimens exhibited an improvement in compressive strength after several cycles of severe weather exposure. The CMU specimens, however, exhibited degradation in their compression strength capacity. The water absorption was higher in RCMUs than it was in the CMU prisms. Copyright © 2017, American Concrete Institute. All rights reserved.
48th AIAA Aerospace Sciences Meeting Including the New Horizons Forum and Aerospace Exposition | Year: 2010
The University of Alabama through sponsorship by the National Science Foundation's Science Technology Engineering and Mathematics (STEM) Office implemented a summer bridge program entitled Engineering Math Advancement Program (E-MAP) incorporating Living Learning Laboratories developed by each of the engineering disciplines. In this paper the E-MAP is summarized and importance of introducing students to experimental, hand-on research at an early level is discussed. Paper also outlines the expected roles of a mentor to ensure the success of students. The impact of the hands-on experience on the student learning is given. Copyright © 2010 by Karen Boykin, Sandy Wood, Celina Bochis, Semih Olcmen.
Bew M.,Innovation and Skills |
Palmer D.,BSI Group |
SSS 2015 - 10th International Space Syntax Symposium | Year: 2015
The pervasive deployment of "smart city" and "smart building" projects in cities world-wide is driving innovation on many fronts including; technology, telematics, engineering and entrepreneurship. This paper focuses on the technical and engineering perspectives of BIM and smart cities, by extending building and urban morphology studies as to respond to the challenges posed by Big Data, and smart infrastructure. The proposed framework incorporates theoretical and modelling descriptions to verify how network-based models can act as the backbone skeletal representation of both building and urban complexity, and yet relate to environmental performance and smart infrastructure. The paper provides some empirical basis to support data information models through building dependency networks as to represent the relationships between different existing and smart infrastructure components. These dependency networks are thought to inform decisions on how to represent building and urban data sets in response to different social and environmental performance requirements, feeding that into void and solid descriptions of data maturity models. It is concluded that network-based models are fundamental to comprehend and represent the complexity of cities and inform urban design and public policy practices, in the design and operation phases of infrastructure projects.
Color Research and Application | Year: 2015
In an unconstrained colour naming experiment conducted over the web, 330 participants named 600 colour samples in English. The 30 most frequent monolexemic colour terms were analyzed with regards to frequency, consensus among genders, response times, consistency of use, denotative volume in the Munsell and OSA colour spaces and inter-experimental agreement. Each of these measures served for ranking colour term salience; rankings were then combined to give a composite index of basicness. The results support the extension of English inventory from the 11 basic colour terms of Berlin and Kay to 13 terms by the addition of lilac and turquoise. © 2015 Wiley Periodicals, Inc.
McCool G.E.,Degenkolb Engineers |
Wheat H.G.,University of Texas at Austin |
Breen J.E.,Civil |
Proceedings of the International Offshore and Polar Engineering Conference | Year: 2013
Post-tensioned concrete structures have been gaining in popularity over the past few decades. When properly designed, such structures allow for longer span lengths, reduced cracking, and less reinforcement than reinforced concrete structures. Their use of higher strength steel and the exposure to higher stresses, however, can result in increased vulnerability to corrosion damage. Moreover, recent high-profile failures of these types of structures have been linked to materials issues and construction procedures. As a result of the heightened interest in post-tensioned concrete structures, two research projects (Test Program 1 and Test Program 2) were carried out on a number of post-tensioning systems involving several different prestressing strand types. The objective of the second project (Test program 2) was to evaluate the corrosion performance of a number of post-tensioning materials and systems in an effort to increase the durability of post-tensioned concrete structures. The results of forensic analysis after long-term exposure in the second research project will be described in this paper. Copyright © 2013 by the International Society of Offshore and Polar Engineers (ISOPE).
Jung S.,Florida A&M University |
Kim S.-R.,Dong - A University |
Patil A.,Florida A&M University |
Ocean Engineering | Year: 2015
Offshore wind turbine towers experience large base moments because of wind and wave loading. The flexibility of the foundation should be considered when analyzing the structural response of towers. Previous studies showed that conventional p-y curves are not suitable in designing the foundation. More advanced methods, such as the finite element method, are necessary to model the offshore wind turbine foundation. In addition, these studies focused on the analysis of the foundation itself, so the effect on the structural response of the tower merits further research. The present study aimed to compare different foundation modeling approaches, focusing on their effects on the structural response of the wind turbine tower. We integrated wind turbine aerodynamic simulation with different models of the foundation. We confirmed that ignoring the flexibility of the foundation caused significant error in wind turbine tower behavior. Between the p-y curve-based model and finite element-based model, the change in maximum moment was insignificant, but the maximum tilt angle increased over 14% in the finite element model. Therefore, the finite element approach is recommended to obtain a conservative design when large tilt angles may cause serviceability issues. © 2015 Elsevier Ltd. All rights reserved.
Coccia S.,University of California at San Diego |
Bartoli I.,Civil |
Marzani A.,University of Bologna |
Lanza Di Scalea F.,University of California at San Diego |
And 2 more authors.
NDT and E International | Year: 2011
This paper gives insight to the ultrasonic wave propagation in arbitrary cross-section waveguides such as rails, with application to ultrasonic inspection. Due to the geometrical complexity of the rail cross-section, the analytical solution to the wave propagation in the rail is not feasible. A Semi Analytical Finite Element method is described as an alternative yet still robust approach to get the solution of the problem. The free-vibration solution and the forced solution to a laser excitation of the rail head are shown up to a frequency of 500 kHz. The effects of different loading patterns are discussed, and experimental results are provided. The analysis allows for the identification of certain wave modes potentially sensitive to specific types of rail head defects. © 2010 Elsevier Ltd. All rights reserved.
PubMed | Civil, UK Environment Agency, MODUL University Vienna, Institute for Animal Health and Brunel University
Type: Journal Article | Journal: Infectious disease reports | Year: 2014
Zoonotic infections are on the increase worldwide, but most research into the biological, environmental and life science aspects of these infections has been conducted in separation. In this review we bring together contemporary research in these areas to suggest a new, symbiotic framework which recognises the interaction of biological, economic, psychological, and natural and built environmental drivers in zoonotic infection and transmission. In doing so, we propose that some contemporary debates in zoonotic research could be resolved using an expanded framework which explicitly takes into account the combination of motivated and habitual human behaviour, environmental and biological constraints, and their interactions.
PubMed | Civil
Type: Journal Article | Journal: Water research | Year: 2013
Water and wastewater treatment and conveyance account for approximately 4% of US electric consumption, with 80% used for conveyance. Net zero water (NZW) buildings would alleviate demands for a portion of this energy, for water, and for the treatment of drinking water for pesticides and toxic chemical releases in source water. However, domestic wastewater contains nitrogen loads much greater than urban/suburban ecosystems can typically absorb. The purpose of this work was to identify a first design of a denitrifying urban NZW treatment process, operating at ambient temperature and pressure and circum-neutral pH, and providing mineralization of pharmaceuticals (not easily regulated in terms of environmental half-life), based on laboratory tests and mass balance and kinetic modeling. The proposed treatment process is comprised of membrane bioreactor, iron-mediated aeration (IMA, reported previously), vacuum ultrafiltration, and peroxone advanced oxidation, with minor rainwater make-up and H2O2 disinfection residual. Similar to biological systems, minerals accumulate subject to precipitative removal by IMA, salt-free treatment, and minor dilution. Based on laboratory and modeling results, the system can produce potable water with moderate mineral content from commingled domestic wastewater and 10-20% rainwater make-up, under ambient conditions at individual buildings, while denitrifying and reducing chemical oxygen demand to below detection (<3 mg/L). While economics appear competitive, further development and study of steady-state concentrations and sludge management options are needed.