Página 15 dos resultados de 2122 itens digitais encontrados em 0.043 segundos

‣ Design methodologies for the seismic retrofitting of bridges

Otenti, Alexander A. (Alexander Alfred), 1981-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 53 p.; 2223287 bytes; 2223096 bytes; application/pdf; application/pdf
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This paper formulates an earthquake design strategy for bridges. Earthquakes can cause extreme economic damage and loss of life. Structural engineers must be conscience of earthquake slip type, earthquake proximity, and local soil properties when designing a structure. Structures subjected to near-field seismic events feel much complex motions and frequencies than those subjected to far-field events. When designing a structure in a seismic zone it is crucial that the engineer examine a sample of previous earthquake records from the region. Earthquake data is organized into response spectra, time histories, and frequency histories. Response spectra display the spectral displacement, velocity, and acceleration in terms of periods and are of the most interest to structural engineers. Once all of the data is gathered and organized it is necessary to decide on a retrofit strategy. Retrofitting involves either strengthening the bridge or shifting the period out of the power range of the earthquake. This paper demonstrates the effectiveness of shifting the period by base isolation with two case studies of isolated bridges and a design example. The design example is a continuation of the Waldo-Hancock Bridge Master of Engineering project completed in 2004 by the author...

‣ Wind-induced dynamic response of bridges

Rousseau, Guillaume, 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 67 leaves; 2034043 bytes; 2033852 bytes; application/pdf; application/pdf
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Wind loading has long played a significant role in bridge design. Some spectacular failures, such as the Tay Bridge (Scotland, 1879), or the Tacoma Narrows Bridge (Washington State, 1940) acted as a painful reminder to engineers in case they had forgotten the importance of wind loading. Today, a constant drive for longer spans in suspension or cable-stayed bridges forces designers to give even more care to wind load. The Golden Gate Bridge (1280 m, San Francisco, built in 1937), which held the record for the longest span for 27 years, is now a distant 7th to the Akashi-Kaikyo (1991 m, Japan, 1998). Different in many ways, the current hunger of Japan and China for new infrastructure leads a renewal of innovation in bridge design and wind engineering. A few projects in Europe or the United States, like the Great Belt Bridge (1624 m, Denmark, 1998), or the Messina Bridge project (3300 m, Italy, not built) are part of the same trend. The design of such a structure is a real challenge for the designer. A good example is given by the Messina Bridge in Veneziano and Van Dyck, 1998. Wind loading in different directions, determination of the reference wind speed, earthquake load, numerous cases of traffic loading ... are investigated thoroughly. The intent of this thesis is to present the essentially dynamic behavior of bridges submitted to wind. The main phenomenon involved will be exposed...

‣ A solution to the inherent list on Nimitz class aircraft carriers

Wolfson, Dianna
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 159 p.; 6886968 bytes; 6893639 bytes; application/pdf; application/pdf
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Nimitz class aircraft carriers possess an inherent list to starboard that their list control systems (LCS) are typically unable to correct while under Combat Load Conditions. As a result, it has become necessary to use fresh water ballast in a number of inner bottom voids and damage control voids to augment the LCS. Maintaining liquid ballast in damage control voids is unacceptable, as it reduces the design counter flooding capability of the ship, and thus reduces ship survivability. In order to restore the ships operational flexibility and achieve the necessary/desired list correction, this study determines the effect of adding solid ballast to a series of voids/tanks identified on the 2nd, 4th, and 8th decks. Based on ballast density, tank location and capacity, ease of ballast installation, minor tank structural modifications, and a decision making cost analysis, solid ballast was determined to be the most advantageous for use in correcting the inherent list on the Nimitz class aircraft carriers. Fresh water ballast was also examined as a possible alternative, but not as extensively due to the large quantity of water required and its limited ability to achieve a list correction. Nimitz class aircraft carriers currently have an average list of 1.5 degrees and a KG of 47 feet.; (cont.) Since their allowable KG cannot exceed 48.5 feet...

‣ Experimental investigation of tearing fracture in sheets under quasi-static loading

Roach, Michael L. (Michael Louis)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 162 leaves; 7587659 bytes; 7594467 bytes; application/pdf; application/pdf
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Although there has been interest in the behavior of metal plates under blast and projectile loading for many years, definitive open-source analysis has only been recently forthcoming. This analysis is most often in the form of scaled recreations of the dynamic blast event, or "live fire" tests. New developments in methods of recreating blast and projectile induced plate failure using a quasi-static approach provide possible, accurate, alternatives to the cumbersome and expensive live fire test. This research endeavors to develop an accurate, quasi-static method of recreating the petalling phase of blast and projectile failure in metal sheets, based on a modified trousers- type test. By using the trousers-type fracture test the overall plastic bending kinematics of the fractured petal is preserved, as well as the mixed mode (mode one and mode three) fracture. Through analytical and qualitative analysis, a testing apparatus to generate this trousers-type, plastic bending and mixed mode fracture was designed and machined. The apparatus was then used to test thin steel sheets of varying thickness (0.419 and 0.724mm) in order to validate the quasi-static method of recreating the petalling phase through a comparison with analytically derived results.; by Michael L. Roach.; Thesis (Nav. E.)--Massachusetts Institute of Technology...

‣ Understanding bus service reliability : a practical framework using AVL/APC data

Cham, Laura Cecilia
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 146 leaves; 10267861 bytes; 10267638 bytes; application/pdf; application/pdf
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Service reliability on a transit system can have significant impacts on its provider and both existing and potential users. To passengers, unreliable service affects their perception of service quality and transit utility compared to other mode choices, while to transit agencies, this translates to loss of ridership and revenues and higher costs to provide additional service to compensate for poor service operations. The introduction of technologies such as Automatic Vehicle Location (AVL) and Automatic Passenger Counters (APC) provides the opportunity to gather large sets of data at relatively low cost and evaluate service to improve performance, schedule planning and operations control. This thesis presents a comprehensive review of key elements of service reliability, focused on the measures of reliability, the causes of unreliability and the application of strategies to improve service. The most significant causes of service reliability are presented: deviations at terminals, passenger loads, running times, environmental factors (or externalities) and operator behavior. Each is reviewed in terms of how they impact service and the complexities and interrelationship between different causes are explored. Also reviewed are the potential preventive and corrective strategies...

‣ Potential efficiency gains in the construction industry from the proper use of information technology

Hsu, Roberta L
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 36 p.; 2683244 bytes; 2684636 bytes; application/pdf; application/pdf
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For many years, technological advances and new software have altered the face of the engineering design sector. Design companies have realized incredible efficiency gains and cost savings due to these improvements, but the construction sector has not been able to do the same. Unlike design firms, contractor businesses as a whole have not embraced IT advancements and taken steps to implement them across all types of construction projects in the most efficient and effective manner possible. Because of this half-hearted attitude towards technological improvements, the same efficiency gains and cost savings found in the design sector have not been attained in the construction sector. The thesis examines different types of IT advancements that have the potential to seriously benefit the construction sector, including electronic document management, 3D modeling, construction sequencing, and laser scanning. Several surveys performed by other engineers and academics interested in the field of information technology in the engineering and construction sector will be examined, and the results of these will provide the basis for discussion regarding the current state of IT saturation in the construction sector as well as its overall effectiveness in providing tangible benefits to users. In addition...

‣ The value of automated fare collection data for transit planning : an example of rail transit OD matrix estimation

Gordillo, Fabio
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 108 leaves
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Traditionally, transit agencies across the world have relied on traveler surveys and manual counts to inform many of their service and operations planning decisions. Today, many agencies can add to their existing planning toolbox the data obtained from new Automated Fare Collection (AFC) technologies. By adding this dataset, transit agencies can boost their analytical capabilities and deal with some planning questions that they previously could not easily address. In fact, while with surveys and manual counts transit agencies were able to form a reasonable snapshot of existing demand on their transit system, with accurate AFC data, planners should be able to get a detailed, continuous and accurate vision of the travel behavior of their customers, at a fraction of the prior cost. Nevertheless, there are some technical and operational issues that can affect the quality of AFC data that must be addressed before the new dataset can be fully integrated into the planning process of transit agencies. This research begins to explore these issues in general as well as in the context of the transit system serving London in the United Kingdom. In particular, it identifies bias in the AFC entry and exit data and develops a methodology for building an unbiased estimate of existing travel patterns on the London Underground.; (cont.) The outcome of the research is a methodology to build unbiased estimates of existing travel patterns. The use of this methodology presents two main advantages over the existing survey methods: (i) the resulting estimate corrects the bias in the Oyster dataset and better reflects existing travel patterns than the traditional survey-based methodology and (ii) the methodology should be easy to replicate...

‣ Recommendations for the design of ultra-high performance concrete structures; Recommendations for the design of UHPC structures

Davila, Ricardo S
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 125 leaves
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New materials frequently require modifications or rewrites of existing construction codes. They may also need new methods for their manufacture and installation. DUCTAL, a new ultra-high performance concrete (UHPC) with enhanced tensile, compressive, and deflective behavior offered by LaFarge, is one such material, and current guidelines for concrete do not sufficiently account for these improved properties. Research by other universities and professional institutions has produced sequential recommendations, beginning with the experiment-based set from the Association Francaise de Genie Civil (AFGC) through the analytically-based set from MIT. In this thesis, the MIT approach is further developed into a coherent method for hardened UHPC design. The first two sections familiarize the reader with the analytical model for UHPC and the evolution in design codes and their philosophical bases. Essential concepts, such as the two-phase matrix-fiber behavior of the material and the use of a maximum crack width criterion to govern design, are explained. Next, the most current design guidelines are presented in full, with attention paid to bending and shear resistance. Comparisons with previous codes demonstrate the ability of these guidelines to produce more structurally efficient sections which consume less material.; (cont.) Analysis of the recommendations themselves will demonstrate the existence of a size effect and the cross-sectional parameters that affect structural efficiency most. Optimization based on the one-dimensional analytical model closes with an analysis of different cross-sections for their structural efficiency...

‣ Building optimization : an integrated approach to the design of tall buildings; Integrated approach to the design of tall buildings

Coleman, Keith LaMar
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 75 p.
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There has been much research done on building optimization that deal with the issues within specific individual fields, such as architecture, structural engineering, and construction engineering. However, in practical application these issues must be addressed in a much more holistic manner as building design is becoming much more inclusive. A balance must be made that addresses the constructability and scheduling concerns of the contractor, the enclosure and spatial concerns of the architect, and finally the load-carrying concerns of the structural engineer. What if these issues were considered altogether and integrated more fully into building optimization? These issues and concerns would indubitably result in compromise solutions and tradeoffs that would have to be taken into account. This research will not only investigate and utilize current optimization techniques for the conceptual design of tall buildings, but also introduce a new metric in the dynamic analysis of high rise structures.; by Keith L. Coleman.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2007.; Includes bibliographical references (p. 73-75).

‣ Condition assessment of GFRP-retrofitted concrete cylinders using electromagnetic waves; Condition assessment of glass fiber reinforced polymer-retrofitted concrete cylinders using electromagnetic waves

Yu, Tzu-Yang (Tzu-Yang Young), 1973-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 370 p.
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The objective of this study is to develop an integrated nondestructive testing (NDT) capability, termed FAR NDT (Far-field Airborne Radar NDT), for the detection of defects, damages, and rebars in the near-surface region of glass fiber reinforced polymer (GFRP)-retrofitted concrete cylinders through the use of far-field radar measurements (electromagnetic or EM waves). In this development, two far-field monostatic ISAR (inverse synthetic aperture radar) measurement schemes are identified for collecting radar measurements, and the backprojection algorithm is applied for processing radar measurements into spatial images for visualization and condition assessment. Reconstructed images are further analyzed by mathematical morphology to extract a numerical index representing the feature of the image as a basis for quantitative evaluation. The components of the development include dielectric modeling of materials, laboratory radar measurements, numerical simulation, and image reconstruction. It is found that using the developed technique the presence of near-surface defects can be detected by the oblique incidence measurements. Radar signals in the frequency range of 8 GHz to 18 GHz are found effective for damage detection in the near-surface region of the specimens. Numerical simulation using the finite-difference time-domain (FDTD) method is conducted to understand the propagation and scattering of EM waves from the defects and inclusions in two-dimensional and three-dimensional GFRP-concrete models. The FDTD simulation is capable of predicting the far-field response of GFRP-concrete cylinders and beneficial to better understanding the pattern of field measurements in the application of the FAR NDT technique.; (cont.) Dielectric properties of materials are investigated for their use in numerical simulation and for improving the precision of reconstructed images. Reconstructed images of GFRP-concrete cylinders with and without artificial features (rebar and defect) clearly indicate the presence of these features. Normal incidence scheme is found to be effective for rebar detection...

‣ Agent-based models of socio-hydrological systems for exploring the institutional dynamics of water resources conflict

Kock, Beaudry E. (Beaudry Evan)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 192 p.
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The Basins-At-Risk theory formulates relations between institutional capacity in a basin and the level of water conflict in that basin, suggesting that higher levels of institutional capacity will lead to reduced levels of water conflict in a given system. I test the substance of this theory using comparative, simulation-based analysis of water resources systems in the USA and Spain. I determine whether, given two artificial societies experiencing water conflict, expanding institutional capacity would indeed lead to reduced conflict levels. I develop and apply two agent-based models of society and hydrology: one for Albacete, Spain, and the other for the Snake River, eastern Idaho,USA. Each model incorporates essential elements of the regional society: real world actors are translated into proactive deliberative agents using a BDI framework; the hydrology/geology is represented either through use of pre-existing models, or basic hydrologic simulation; economic, societal and other dynamics are represented through additional databases and agent rule bases. I apply the models experimentally to explore the societal effects of adding an additional institution to the existing water resources management institutions: ground water banking...

‣ Reinvention through reuse : strategies for the adaptive reuse of large-scale buildings; Strategies for the adaptive reuse of large-scale buildings

Ozik, Dana
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 119 p.
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The practice of adaptive reuse has grown in popularity in the United States over the past few decades, with now about 90% of architect-commissioned work involving some interaction with an existing structure. While the practice of reuse has existed informally in the form of garage-as-guest house or barn-as-garage conversions and so on, it is only since the late 1960s that architects and engineers have begun to approach it critically, as a design problem. It is often lauded for fostering the development of a sustainable built environment, however, it has its unique challenges. This thesis traces a brief history of the designer's role in the sustainable development discourse, with focused attention paid to the adaptive reuse solution. Furthermore, it attempts to identify the challenges and discuss how they each pertain to the architect, the preservationist, and the engineer. Through the examination of reuse case studies, a coarse classification of project typologies. The second portion of the thesis tackles a specific reuse problem in the Old Post Office in Chicago, Illinois. The Post Office was selected because of its heavily planned context, its historical and cultural significance, the real interest that has been expressed in its reuse...

‣ Reanalysis of the settlement of a levee on soft bay mud

Nguyen, Hoang Q. (Hoang Quang)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 366 p.
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Staged construction of embankments on soft ground remains one of the most challenging topics in geotechnical engineering due to the complex shear and consolidation behavior of clays. This thesis presents a case study on the performance of the New Hamilton Partnership (NHP) levee in Novato, California. This 11ft high levee was constructed over 30 ft - 40 ft thick layer of San Francisco Bay Mud during a six-month period in 1996. Settlements along the levee crest were monitored over a period of 5.2 years after the end of construction (until early 2002), at which time URS installed piezometers to measure the existing consolidation stresses (s'vc) within the Bay Mud. URS also conducted state-of-the art field and laboratory test programs to develop well-defined values of preconsolidation stress (s'p) and compressibility parameters for the Bay Mud. However, conventional 1-D consolidation analyses greatly underestimated the measured levee settlements. Hence URS reduced s'p by 20% for the Plaxis FE analyses with the Soft Soil Model (SSM) used to replicate the performance of the existing NHP levee and then to design an expanded levee system. This thesis presents a detailed re-evaluation of the NHP levee performance and of the stress history...

‣ Leveraging infrastructure : sustainable bus rapid transit route planning in Beirut, Lebanon

Nabti, Jumana M., 1976-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 138 p.; 5134067 bytes; 5197925 bytes; application/pdf; application/pdf
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This thesis applies the concepts of urban design, public transportation planning, economic development, and sustainability, to the routing and site plan of a two-kilometer bus rapid transit (BRT) line segment into downtown Beirut, Lebanon; linking a 20- kilometer BRT corridor to the region's core. Previous routing of the segment, which used typical transportation engineering processes produced routes that would degrade the line's quality of service and/or the adjacent land uses. While one route was preferred, none were compelling enough to be advanced to the next planning stage. This thesis explores the possibility that, by expanding the criteria, the route selection and design process can be used to determine an alignment that not only supports high quality transit service, but leverages the capital investment in public transportation to improve environmental quality, economic development, community livability, and transit network connectivity in the areas it serves. In turn, the inclusion of these factors should aid in successful BRT implementation by broadening the base of supporters, and by acknowledging and catering to the physical, social, and political complexity of the project and the project area, substantially increasing project benefits. The project identified a broad range of routes...

‣ Building E-education platform for design-oriented learning

Ning, Hai, 1974-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 155 p.; 7174439 bytes; 7174242 bytes; application/pdf; application/pdf
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Design-oriented learning requires tools that support creative processes and student-to-student and student-to-faculty interactions. While most present E-Education systems perform as the asynchronous distribution channel for teaching material, they usually offer little support for project based design processes. This research maps out the key learning events in design classes at MIT's Department of Mechanical Engineering, and proposes guidelines for building E-Education systems to support the unique characteristics of design-oriented learning. Two creative learning processes are identified and two independent, yet tightly related, software systems are implemented and evaluated. The first application, the Peer Review and Engineering Process (PREP), is a web system that helps instructors and students conduct and manage peer review evaluation of design concepts. The second is a real time application called InkBoard that leverages the Tablet PC and Ink medium to provide real-time collaborative sketching over TCP/IP networks. A new streaming network protocol for transferring Ink objects is proposed and implemented. A comparative study against other ink-enabled protocols is also presented.; by Hai Ning.; Thesis (Ph. D.)--Massachusetts Institute of Technology...

‣ Structural loading of cross deck connections for trimaran vessels

Rhoads, Jason L
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 176 p.; 1625179 bytes; 2504135 bytes; application/pdf; application/pdf
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This work investigates the fundamental relationships of wave loading on cross deck structures for trimaran vessels. In contrast with a monohull ship, trimaran vessels experience several possible structural loading cases including: longitudinal bending, transverse bending, torsional bending, spreading and squeezing of hulls, inner and outer hull slam pressures, wet deck slam pressures, loading from ship's motions, and whipping of slender hulls. This work investigates wave loading cases that result in transverse and torsional bending of the cross deck structure. The wave loading cases investigated include: side hull troughing and cresting in longitudinal waves, side hull torsion in longitudinal waves, and transverse hogging and sagging. For each of these load cases, a design load using a fully statistical sea state was derived using an analytical model of a trimaran represented by rigidly connected box barges. The design loadings with a reliability index of 5 for almost 500 trimaran configurations were calculated varying main hull length, side hull length, side hull transverse placement, and side hull longitudinal placement. The design loadings were curve fit to a fourth order polynomial in the three independent variables.; (cont.) The load predictions of the analytical box model of a trimaran were applied to a trimaran vessel with a realistic hull form using the finite element ship structural analysis program MAESTRO. Given the number of approximations and assumptions in the analytical model...

‣ Light-weight materials selection for high-speed naval craft

Torrez, Joseph B. (Joseph Benjamin)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 111 p.
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A decision analysis study was conducted on the process of materials selection for high-speed naval craft using the Modified Digital Logic (MDL) method proposed by B. Dehgham-Manshadi et al in ref [17]. The purpose is to show how this method along with Ashby's material selection process can be integrated to provide a comprehensive tool designed specifically for light-weight material optimization. Using Ashby's Material Selection Charts and the MDL method, a step by step material selection process is outlined. Furthermore, a comparison of the materials based on equivalent plate uni-axial ideal elastic compressive stress was completed using the American Bureau of Shipbuilding (ABS) Guide for Building and Classing High-Speed Naval Craft and then an evaluation was done to optimize material selection depending on the designer's preference for weight and cost. The potential materials for evaluation were selected using Naval Sea Systems Command (NAVSEA) references for the most current materials in use, or being evaluated, for light weight naval construction. The results demonstrate the feasibility of using the MDL method to select one or more materials based on desired mechanical and structural characteristics. The study also introduces the potential use of non-traditional materials in Naval Architecture...

‣ Clean energy investments in an uncertain future

Harrison, Jessica (Jessica Kit)
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 96 p.; 7160104 bytes; 7164069 bytes; application/pdf; application/pdf
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The energy sector faces a multitude of challenges related to climate change and energy security. These challenges will likely prompt considerable changes in the coming decades, including significant investment and new market design. To help fulfill multiple goals and limit the necessary tradeoffs among them, industry and policymakers alike are looking to new technologies. However, uncertainty regarding the challenges, the solutions, and the behavior of the energy system, make it difficult to discern which investment is right for what time. This thesis reviews the potential changes in today's energy system and examines the difficulties of addressing challenges that appear urgent yet elusive. An extensive literature review considers the problems of clean energy investment decision-making in modern energy systems, and evaluates the potential contributions of a real options approach and system dynamics. A case study on the market growth of Gas-to-Liquids technology provides more detail on the use of system dynamics to gauge market uncertainties. Admitting to the lack of appropriate tools to objectively evaluate strategies for tackling today's energy challenges, this thesis helps answer why such questions as the appropriate timing investment are so difficult to answer...

‣ The "greening" of the concrete industry : factors contributing to sustainable concrete

Kuntz, Lauren Midori
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 41 leaves; 2963445 bytes; 2965057 bytes; application/pdf; application/pdf
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The dawn of the new millennium has brought to light the environmental concerns of global warming, pollution, limited landfill space, and depleting natural resources. These concerns, compounded by the growing global population, have peaked interests in sustainability. In order to accommodate the world's people, industrialization and urbanization is at an all-time high, making the construction industry one of the biggest consumers of energy and resources and one of the biggest producers of waste. With its versatility and low cost of materials, construction, and maintenance, concrete has emerged as the material of choice for new construction in the 20th and 21st centuries. With over 10 billion tons of concrete being produced annually, the concrete industry is the largest consumer of natural resources and one of the biggest contributors to greenhouse gas emissions worldwide. In order to reduce the harmful impacts of such a valuable construction material, it is imperative that the concrete industry take strides to become a "green" material.; (cont.) This paper outlines strategies to reduce the environmental impacts of concrete through recycling, conservation, industrial ecology, and creating more durable structures. Not only do these methods contribute to the reduction of carbon-dioxide emissions through reducing Portland cement production and saving valuable natural resources by conserving water and using alternatives to natural aggregates in concrete mix-designs...

‣ Development of a rating system for sustainable bridges

Hunt, Lauren R., 1982-
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 41 leaves; 2171334 bytes; 2173995 bytes; application/pdf; application/pdf
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One of the latest trends in engineering is sustainable design, which is designing so that resources are available for many generations to come. Sustainable design considers the ecological, economic, and socio-cultural environments and works to balance all three. Sustainable bridge design is still in development, and clear standards and recommendations have not been formalized as they have in building design. The U.S. Green Building Council's Leadership in Energy and Environmental Design (LEEDTM) Green Building Rating System evaluates sustainable building design by awarding points based on measurable criteria. The LEEDTM rating system deals with buildings, but a similar system could be developed that would apply to bridge design. This report proposes a rating system for sustainable bridge design based on current practices and emerging technologies. Three bridges (either new or under construction) were rated using the system and the results are presented. Also discussed are steps and obstacles for implementation.; by Lauren R. Hunt.; Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2005.; Includes bibliographical references (leaf 41).