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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Rising Water: Harnessing the Process of Sedimentation for a Flood Resilient Coastal Landscape

Courtney, Paige Therese 26 June 2017 (has links)
This thesis examines the relationships between rising water levels, vulnerable land, and sedimentation within the Chesapeake Bay watershed. Climate induced sea level rise threatens low lying coastal land, especially in regions of continuing subsidence such as the Chesapeake Bay. Alterations to shorelines over time have impacted the ability of coastal landscapes to capture and build up sediment, exposing them to continual erosion. The low lying neighborhood of Belle View along the Potomac River is the focus of the investigation due to its vulnerability to flooding and its cultural and ecological connections to the adjacent landscapes of Dyke Marsh and the George Washington Memorial Parkway. Through careful placement of breakwater infrastructure, sediment will build over time as the water rises, mitigating the effects of coastal flooding in this region. Alterations to the landscapes of the marsh and parkway allow for their cultural and recreational values to be strengthened over time as the landscape adjusts to the rising sea level. / Master of Landscape Architecture / Climate change, or the belief that human activity is altering the earth's climate, is projected to increase the occurrence of flood events due to water levels rising over time from glaciers melting. Previously, shorelines have been hardened with levee or seawall infrastructure to creates a barrier between the water and developed land. Hardened shorelines may increase water velocity and reflect wave energy in riverine landscapes, consequentially disturbing natural shorelines. This disturbance leads to the gradual loss of sediment over time and therefore a loss of ground elevation. When landscapes lose elevation, they become more vulnerable to rising water levels and flooding. This relationships between shoreline types, sedimentation, rising water, and vulnerability inspired me to discover and design a threatened landscape that would capture sediment within the river's water column to build elevation over time and protect the adjacent development from rising water. The area encompassing the low lying neighborhood of Belle View, Dyke Marsh, and the George Washington Memorial Parkway along the Potomac River is the focus of the investigation due to its vulnerability to flooding. With a careful understanding of sediment capture infrastructure dynamics, the design introduces breakwaters on the site to allow sediment to build over time as the water rises. This research and design thesis demonstrates a strategy to create landscapes that will evolve over time to mitigate future flooding events and create more resilient landscapes.
152

A Beachfront High-rise

Schieble, Allison Leigh 12 June 2012 (has links)
This beachfront high-rise, sited in Virginia Beach, Virginia, is inspired by Le Corbusier's Unité dâ Habitation in Marseille with floors that switch back to boast views of the Chesapeake Bay and Lynnhaven Inlet. Its large glazed facades are oriented to the west, so residents can enjoy evening sunsets from their living rooms; and to the east, so they can wake up to sunrises from their bedrooms. Its staggered concrete shear walls shield the structure from north winds. The high-rise is comprised of seven towers; each containing sixteen condos arranged over twenty-eight stories. The building features retail and resident services on the ground floor, a five-story parking garage, and a rooftop pool, restaurant, and sun deck. / Master of Architecture
153

Progressive Collapse Evaluation of High Rise Steel Structures due to Sudden Loss of Structural Members

Stephen, D., Ye, J., Lam, Dennis January 2012 (has links)
No / Damage or instantaneous loss of critical structural members due to unforeseen events like impact, blast and natural disasters often propagates progressive collapse as a result of complex redistribution of stresses within the structural system. In severe conditions, in which the structure lacks the ability to absorb the stresses in seeking a new equilibrium state, it could result in partial or total collapse of the building. Current design guidelines such as GSA 2003 recommend single removal of load bearing member for progressive collapse assessment. However, triggering events may affect one or more structural member resulting in partial or total collapse of the structure. This paper presents the various effect of sudden column loss on the redistribution of forces in structural members that determine the equilibrium state of the structure.
154

Development and Uncertainty Quantification of Hurricane Surge Response Functions and Sea-Level Rise Adjustments for Coastal Bays

Taylor, Nicholas Ramsey 16 June 2014 (has links)
Reliable and robust methods of extreme value based hurricane surge prediction, such as the Joint Probability Method (JPM), are critical in the coastal engineering profession. The JPM has become the preferred surge hazard assessment method in the United States; however, it has a high computational cost: one location can require hundreds of simulated storms, and more than ten thousand computational hours to complete. Optimal sampling methods that use physics based surge response functions (SRFs), can reduce the required number of simulations. This study extends the development of SRFs to bay interior locations at Panama City, Florida. Mean SRF root-mean-square (RMS) errors for open coast and bay interior locations were 0.34 m and 0.37 m, respectively; comparable to expected ADCIRC model errors (~0.3 m—0.5 m). Average uncertainty increases from open coast and bay SRFs were 10% and 12%, respectively. Long-term climate trends, such as rising sea levels, introduce nonstationarity into the simulated and historical surge datasets. A common approach to estimating total flood elevations is to take the sum of projected sea-level rise (SLR) and present day surge (static approach); however, this does not account for dynamic SLR effects on surge generation. This study demonstrates that SLR has a significant dynamic effect on surge in the Panama City area, and that total flood elevations, with respect to changes in SLR, are poorly characterized as static increases. A simple adjustment relating total flood elevation to present day conditions is proposed. Uncertainty contributions from these SLR adjustments are shown to be reasonable for surge hazard assessments. / Master of Science
155

Art Center

Li, Ting 29 June 2015 (has links)
For any artist, imagination is a powerful and necessary instrument for everyday creation. It is like a magical engine that drives the artist forward. But what is imagination? How do we keep this engine running nonstop? According to the Italian philosopher Giovan Battista Vico, imagination is nothing but extended or compounded memory, imagination is nothing but the springing up of reminiscences, and ingenuity or invention is nothing but the working over of what is remembered.So we can easily understand that people create or invent things out of what they have seen, what they have experienced, and what they have engaged with their own bodies. In my thesis, I'm not competing with the artists in imagination or creation, but I'm trying to offer them this architectural environment that would be transfigured into memory through senses. The artists living and working in this tower building are encouraged to move vertically through stairways and vertically aligned public spaces. By engaging the body and senses in this vertical movement, the artists would find their way out of the urban canyon to the sky of imagination. They would also be able to live lightly above the bustling world of reality. / Master of Architecture
156

Numerical Modeling of the Hydrothermal System at East Pacific Rise (EPR) 9 Degrees 50' N Including Anhydrite Precipitation

Kolandaivelu, Kannikha Parameswari 09 July 2015 (has links)
Seafloor hydrothermal systems have been intensively studied for the past few decades; however, the location of recharge zones and details of fluid circulation patterns are still largely uncertain. To better understand the effects of anhydrite precipitation on hydrothermal flow paths, we conduct 2-D numerical simulations of hydrothermal circulation at a mid-ocean ridge using a NaCl-H2O numerical code. The simulations focus on East Pacific Rise hydrothermal system at 950N due to availability of key observational data to constrain the models. Seismicity data that is available suggests that fluid flow is primarily along axis and that recharge is focused into a small zone near a 4th order discontinuity in the ridge axis. Simulations are carried out in an open-top square box 1500 m on a side maintained at a surface pressure of 25 MPa, and nominal seawater temperature of 10 C. The sides of the box are assumed to be impermeable and insulated. A constant temperature distribution is maintained along the bottom of the box consisting of a 1000 m long central-heated region maintained at 450 C to represent the axial magma chamber and ensure P-T conditions for phase separation; a linearly decreasing temperature profile from 450 to 300 C is maintained along the 250 m long segments adjacent to the heated region to delineate the recharge zone. We constructed a homogeneous model with a uniform cell size of 25 m with a permeability of 10-13 m2 and a similar model with a 200 m thick layer 2A region with a permeability of 10-12 m2. For the homogeneous model the simulations were run for 100 years to approximate steady state conditions and the model with layer 2A was run for 50 years. Assuming that anhydrite precipitation resulted from the decrease in solubility with increasing temperature as downwelling fluid gets heated, the rate of porosity decrease and sealing time was calculated at 50 and 100 years. The results showed that sealing occurred most rapidly at the bottom of the recharge areas near the base of the high-temperature plumes, where complete sealing occurred after ~55-625 years for an initial porosity of 0.1. The simulations also suggested that sealing would occur more slowly at the margins of the ascending plumes, with times ranging between ~ 80 and 5000 years. The sealing times in the deep recharge zone determined in these simulations are considerably greater than estimated from 1D analytical calculations, suggesting that with a 2D model, focused recharge at the EPR 950N site may occur, at least on a decadal time scale. More detailed analyses are needed to determine whether such focused recharge can be maintained for longer times. / Master of Science
157

A structural system for multi-story construction in prestressed-precast concrete

Alvarado, Eduardo E. January 1962 (has links)
It is the major purpose of this thesis to examine, through a practical engineering problem, the different aspects affecting the development of the structural concept. For this purpose, a prestressed-precast concrete structural system for multi-story construction is developed. After the introductory sections, the development of the structural system is explained in the third section. The section includes an analysis of the system, as well as a description of the individual component of the structure and their interaction. The analysis provides a corroboration of the adequacy of the concepts of the system. Illustration aid in the explanation of the problems involved. / Master of Science
158

Sensitivity of Steel Purlins to Changes in Application of Wind Loads

Douglas, Mary Keith 25 June 2020 (has links)
This project studied the effects of wind tunnel test loads applied to purlins in low rise steel buildings compared to those determined with currently recognized wind loading provisions. The National Institute of Standards and Technology (NIST) database of low-rise building wind tunnel test data, which was collected at the University of Western Ontario (UWO) boundary layer wind tunnel, was used to model a realistic wind load scenario. Pressure coefficient data recorded in the database was applied statically to individual purlins in a typical design for the size of buildings studied. These results were then compared to those obtained using the wind design provisions in ASCE 7-16 Chapter 30 for Components and Cladding. The primary data of interest was shear and moment values along the length of the purlins, which were modeled as continuous beams. Comparisons were made between the resultant shear and moment from both the wind tunnel load and ASCE 7-16 load values at 1-foot increments along the length of the purlin. The results showed that the overall peak values obtained from wind tunnel test loads were 3% to 49% higher than those calculated using ASCE 7-16 for purlins that were on the windward edge of the building. Purlins on the interior of the building varied in whether they exceeded the loads calculated with ASCE 7. Changing the height of the structure and the terrain roughness both increased the number of purlins that were lower than the values provided in ASCE 7-16 in the interior of the structure. / Master of Science / Purlins are roof members used in low rise steel buildings to transmit wind loads applied to the roof of the structure to the frame of the building. This project studied the effects of applying loads to purlins using methods specified by the code compared to those found in a wind tunnel, to look at the similarity of the values and model the actual behavior of the purlins more accurately. For this study, wind tunnel test data obtained from the National Institute of Standards and Technology (NIST) database was applied to the purlins and the shear and moment was calculated. These results were compared to the current code requirements provided in the American Society of Civil Engineers (ASCE) 7 document: Minimum Design Loads and Associated Criteria for Buildings and Other Structures. The results showed that the loads developed in the purlins subjected to wind tunnel test loadings were 3% to 49% higher on the edge of the building than those that had the ASCE 7 design loads applied. More accurately modeling the behavior of the purlins using wind tunnel test data and beam models showed that in locations where the purlins received the maximum wind force, the ASCE 7 requirements for components and cladding tended to be lower than the wind tunnel test data. However, in locations where the purlins were not experiencing the maximum wind force, the ASCE 7 requirements tended to overpredict the loads, based on the use of symmetric high wind areas to design for all wind angles.
159

The Social Cascades of Exposure to Flood Induced Natech Events on Vulnerable Populations in Hampton Roads, Virginia

Crawford, Margaret Calyer 31 May 2022 (has links)
Coastal flood impacts are increasing in severity with the rising sea levels, causing damage to ecological and human systems. Climate-hazards may also result in cascading impacts, where an initial disaster sets off a chain of events that extends beyond the initial spatiotemporal point of impact. Coastal flood events may result in consecutive disasters in which the initial flood event results in a secondary technological disaster, prompting disruptions to socio-economic systems and resulting in a public health crisis. Flood events that trigger technological emergencies through the inundation and dispersion of hazardous materials are known as Natech disasters. However, current research on the cascading impacts of Natech events is limited. Hampton Roads, Virginia, is experiencing an accelerated rate of sea level rise and a proportionally higher risk of storm surge, potentially leading to a greater risk of Natech disasters. The main objective of this study is to evaluate the impact of Natech events on surrounding communities in Hampton Roads. This study uses geospatial analysis to identify the current (2021) and future (2051) threats of flood-induced Natech disaster and assess its exposure to different coastal populations and ecosystems. The present study calculated the Flood Hazard Density Index (FHDI), using a 1-mile radius around the significantly flooded facilities to determine the spatial dispersion of Natech disasters. The flood risks were determined using the 100-year flood plain and intermediate (RCP 4.5) climate scenario. The risk of a Natech disaster was identified by combining the spatial extent of flood risk with the location of Toxics Release Inventory (TRI) facilities and National Priorities List (NPL) designated Superfund sites. The exposed environmental and social systems to Natech events were chosen through the literature gap analysis. Sociodemographic data from the American Community Survey were collected to examine its correlation with 2021 and 2051 FHDI-affected block groups. Findings reveal that block groups with higher proportions of minorities, people in poverty, and people without a vehicle experience significant exposure to a Natech disaster compared to those who are living further away from the TRI and Superfund facilities. Additionally, open water and wetland environments will also experience significant exposure to Natech events, which could indicate a loss of ecosystem services. This study suggests a need for proactive policy and programmatic interventions to minimize the potential impacts of Natech events on the surrounding communities, such as the remediation of Superfund sites and the development of hazard mitigation plans for TRI facilities. / Master of Science / Coastal flood impacts are increasing in severity with the rising sea levels, causing damage to ecological and human systems. Climate-hazards may also result in cascading impacts, where an initial disaster sets off a chain of events that extends beyond the initial spatial origin of impact, prolonging the effects of the initial disaster. Coastal flood events may result in consecutive disasters, where an initial flood event results in a secondary technological disaster, prompting disruptions to socio-economic systems and resulting in a public health crisis. Flood events that trigger technological emergencies causing the inundation and dispersion of hazardous materials are known as Natech disasters. However, current research on the cascading impacts of Natech events is limited. Hampton Roads, Virginia, is experiencing accelerated sea level rise and a proportionally higher risk of storm surge, potentially leading to a greater risk of Natech disasters. The main objective of this study is to evaluate the impact of Natech events on surrounding communities in Hampton Roads. This study uses geospatial analysis to identify the current (2021) and future (2051) threats of flood-induced Natech disaster and assess its exposure to different coastal populations and ecosystems. The present study used a 1-mile radius around the significantly flooded facilities to determine the spatial dispersion of Natech diasters. The flood risks were determined using the 1 in 100 annual flood risk and an intermediate climate projection. The risk of a Natech disaster was identified by combining the spatial extent of flood risk with the location of U.S. Environmental Protection Agency (U.S. EPA) regulated Toxics Release Inventory (TRI) facilities and National Priorities List (NPL) designated Superfund sites. The most susceptible social, economic, and environmental subsystems to Natech events were identified using a literature gap analysis. Sociodemographic data were collected from the American Community Survey to examine its relationship to the 2021 and 2051 Natech affected census block groups. Findings reveal that block groups with higher proportions of minorities, people in poverty, and people without a vehicle experience significant exposure to a Natech disaster compared to those who are living further away from the TRI and Superfund facilities. Additionally, open water and wetland environments will also experience significant exposure to Natech events, which may indicate a loss of ecosystem services. This study suggests a need for proactive policy and programmatic interventions to minimize the potential impacts of Natech events on the surrounding communities, such as the remediation of Superfund sites and the development of hazard mitigation plans for TRI facilities.
160

Rosslyn Waterfront Complex: Bridge the City and the River Architecturally

Wang, Manting 16 February 2018 (has links)
I consider that either walking along the riverbank or floating down the river by boat and enjoying the journey by interacting with nature is a fundamental human right. Wandering in the concrete jungle, humming while beatboxing, dancing, and skateboarding can also be great pleasures. However, as cities increasingly cover over nature with urban constructions, highways, for instance, they deprive people's right to access the river by erecting a barrier between city and nature. Citizens are the reason that cities exist. So many vivid social activities happen in the concrete jungle every day. Yet, out urban lifestyles belittle nature as it is obscured by the city. It would be much more beautiful, inspiring, and healthy if we can find ways to develop cities in harmony with nature, allowing citizens to bring our urban textures to the ever-flowing river. In my thesis, I explore the possibilities of bringing the city and the river, architecturally. / Master of Architecture / I consider that either walking along the riverbank or floating down the river by boat and enjoying the journey by interacting with nature is a fundamental human right. Wandering in the concrete jungle, humming while beat boxing, dancing and skateboarding can also be great pleasures. However, as cities increasingly cover over nature with urban constructions, highways for instance, they deprive people’s right to access the river by erecting a barrier between city and nature. Citizens are the reason that cities exist. So many vivid social activities happen in the concrete jungle every day. Yet, out urban lifestyles belittle nature as it is obscured by the city. It would be much more beautiful, inspiring, and healthy if we can find ways to develop cities in harmony with nature, allowing citizens to bring our urban textures to the ever-flowing river. In my thesis, I explore the possibilities of bringing the city and the river, architecturally.

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