You searched for +publisher:"Virginia Tech" +contributor:("Sotelino, Elisa D.").
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Virginia Tech
1.
Wang, Dong.
A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture.
Degree: PhD, Civil Engineering, 2011, Virginia Tech
URL: http://hdl.handle.net/10919/38667 
► The fatigue damage is one of the most common distresses observed on the asphalt concrete pavement. The initiation and propagation of the fatigue damage is…
(more)
▼ The fatigue damage is one of the most common distresses observed on the asphalt concrete
pavement. The initiation and propagation of the fatigue damage is a complicated phenomenon
and very difficult to detect. In order to thoroughly understand the fatigue of asphalt concrete, the
behaviors of the key components of asphalt concrete under cyclic loading are investigated
respectively. A new experiment method is developed to test the performances of asphalt binder,
mastic and mixture under cyclic loading, which provides a tool to unify the fatigue test method
for both binding medium and asphalt mixture. Using the new fatigue test method, the effects of
loading magnitude, temperature and loading rate to the performance of the asphalt binder under
cyclic loading are estimated. Mastic and mixture specimens are prepared by adding fillers and
controlled-size aggregates into the asphalt binder. The effects of filler content to the performance
of mastic specimen are discussed. The differences between the test results of mastic and mixture
are compared and analyzed. Incorporated with the new fatigue test, x-ray tomography system is
used in this study to: 1. Analyze the structure change of the mastic specimen before and after the
fatigue test. 2. Compare the void content differences between the mastic and mixture specimens.
3. Reconstruct the 3-
D internal structures of mastic and mixture specimens to build up the digital
specimens. The digital specimens are used in the fatigue simulation of the asphalt binder, mastic
and mixture specimens based on the finite element method. The asphalt binder, filler and
aggregate are treated as different materials. Damage parameter is introduced to model the
degradation of elastic modulus of the asphalt binder caused by fatigue damage. Direct cyclic
analysis available in ABAQUS is used to obtain the response of the material after large number
of loading cycles. The basalt fibers are dispersed into the asphalt binder and mastic specimens,
the effects of the basalt fiber to the performances of the binder and mastic at low temperature are
analyzed using both experimental and FEM modeling methods.
Advisors/Committee Members: Wang, Linbing (committeechair), Sotelino, Elisa D. (committee member), Dove, Joseph E. (committee member), Batra, Romesh C. (committee member).
Subjects/Keywords: Asphalt mixture; Fatigue; X-ray Tomography; Finite Element Method
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APA (6th Edition):
Wang, D. (2011). A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/38667
Chicago Manual of Style (16th Edition):
Wang, Dong. “A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture.” 2011. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/38667.
MLA Handbook (7th Edition):
Wang, Dong. “A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture.” 2011. Web. 17 Jan 2021.
Vancouver:
Wang D. A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture. [Internet] [Doctoral dissertation]. Virginia Tech; 2011. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/38667.
Council of Science Editors:
Wang D. A micro-scale method to associate the fatigue properties of asphalt binder, mastic and mixture. [Doctoral Dissertation]. Virginia Tech; 2011. Available from: http://hdl.handle.net/10919/38667
Virginia Tech
2.
Woodworth, Michael Allen.
Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling.
Degree: PhD, Civil Engineering, 2013, Virginia Tech
URL: http://hdl.handle.net/10919/23683
► Bridges are critical pieces of infrastructure important to public safety and welfare. Fires have the potential to damage bridges and have been responsible for taking…
(more)
▼ Bridges are critical pieces of infrastructure important to public safety and welfare. Fires have the potential to damage bridges and have been responsible for taking many bridges out of service. The hazard fire poses to bridges is a little studied risk unlike more common threats such as impact, scour and earthquake. Information on the rate of occurrence of bridge fires and the mechanisms of structural response of bridges subjected to fire are both vital to policy makers seeking to address the hazard rationally. The investigation presented developed frequency statistics of bridge fire incidents from several sources of vehicle accident and fire statistics. To further investigate the fire hazard a computational model integrating the simulation of large fires and the simulation of bridge superstructure mechanical response was created. The simulation was used to perform a parametric study of fire size and location to investigate the relationship between these parameters and damage tot bridge super-""structure. The statistics investigation resulted in an observed rate of fires due to vehicle accidents of approximately 175 per year. Approximately one of these per year was the result of a tanker truck carrying a flammable liquid leading to extensive superstructure damage. The simulation showed that a tanker fire resulted in permanent damage to the bridge by several measures where as the affects of a bus fire were minimal. The simulations also demonstrated the mechanisms of bridge response; the importance of girder temperature in that response; and the differences in the response to a tanker fire that can lead to collapse.
Advisors/Committee Members: Sotelino, Elisa D. (committeechair), Wright, William J. (committeechair), Roberts-Wollmann, Carin L. (committee member), Lattimer, Brian Y. (committee member).
Subjects/Keywords: Bridge; Fire; Girder; Accidents; Statistics; ABAQUS; FDS
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APA (6th Edition):
Woodworth, M. A. (2013). Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/23683
Chicago Manual of Style (16th Edition):
Woodworth, Michael Allen. “Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling.” 2013. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/23683.
MLA Handbook (7th Edition):
Woodworth, Michael Allen. “Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling.” 2013. Web. 17 Jan 2021.
Vancouver:
Woodworth MA. Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling. [Internet] [Doctoral dissertation]. Virginia Tech; 2013. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/23683.
Council of Science Editors:
Woodworth MA. Fire Hazard Assessment for Highway Bridges with Thermal Mechanical Modeling. [Doctoral Dissertation]. Virginia Tech; 2013. Available from: http://hdl.handle.net/10919/23683
Virginia Tech
3.
Cross, Benjamin Thomas.
Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders.
Degree: PhD, Civil Engineering, 2012, Virginia Tech
URL: http://hdl.handle.net/10919/26190
► The use of high compressive strengths in prestressed bridge girders can lower costs by allowing for longer spans, increased girder spacing, and smaller cross-sections. If…
(more)
▼ The use of high compressive strengths in prestressed bridge girders can lower costs by allowing for longer spans, increased girder spacing, and smaller cross-sections. If high strength lightweight concrete (HSLWC) is used, these advantages are further enhanced due to the corresponding reduction in self-weight. Additional benefits can then be realized in the form of more traffic lanes, increased load capacity, smaller substructures, reduced crane capacity requirements, and lower shipping costs.
Despite the possible economic savings, HSLWC has been used infrequently in prestressed bridge girder applications across the nation. While recent research has been performed to extend the applicability of current bridge design specifications to normal weight concretes with strengths as high as 18 ksi, little
has been done by comparison with regards to HSLWC. The purpose of the research in this report was to assess whether current bridge design specifications for transfer length, development length, prestress loss, camber, and flexural capacity are satisfactory for use with fully-bonded, pretensioned flexural members consisting of HSLWC and to make recommendations for improvements where necessary.
Twelve high strength pretensioned beams of variable unit weight (eight lightweight beams and
four normal weight beams) and strand size (eight beams with 0.5-in. strand and four beams with 0.6-in. strand) were cast at the Thomas M. Murray Structural Engineering Laboratory at
Virginia Tech. These beams were allowed to sit for a period of several months after fabrication while measurements were taken regarding transfer length, prestress loss, and camber. After this period, the beams were load tested to collect development length data, flexural data, and further data related to prestress loss. In
addition to the laboratory cast beams, prestress loss and camber data from six full-size bridge beams (five lightweight beams and one normal weight beam) cast as part of a separate project at
Virginia Tech was examined. Analysis of the results for all beams shows that with a few caveats, the current AASHTO LRFD Specifications and other design methods examined regarding the topics under consideration are satisfactory for use in the design of HSLWC pretensioned bridge girders with properties similar to those of the beams studied.
Advisors/Committee Members: Easterling, William Samuel (committee member), Sotelino, Elisa D. (committee member), Cousins, Thomas E. (committeecochair), Roberts-Wollmann, Carin L. (committeecochair).
Subjects/Keywords: prestress loss; development length; transfer length; high strength concrete; lightweight concrete; camber growth; pretensioned girders
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APA (6th Edition):
Cross, B. T. (2012). Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/26190
Chicago Manual of Style (16th Edition):
Cross, Benjamin Thomas. “Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders.” 2012. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/26190.
MLA Handbook (7th Edition):
Cross, Benjamin Thomas. “Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders.” 2012. Web. 17 Jan 2021.
Vancouver:
Cross BT. Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders. [Internet] [Doctoral dissertation]. Virginia Tech; 2012. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/26190.
Council of Science Editors:
Cross BT. Structural Performance of High Strength Lightweight Concrete Pretensioned Bridge Girders. [Doctoral Dissertation]. Virginia Tech; 2012. Available from: http://hdl.handle.net/10919/26190
Virginia Tech
4.
Nahid, Mohammad N.
Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure.
Degree: PhD, Mechanical Engineering, 2015, Virginia Tech
URL: http://hdl.handle.net/10919/73909
► The exposure from a localized vehicle fire has been observed to produce excessive damage onto highway bridge structural elements including complete collapse of the infrastructure.…
(more)
▼ The exposure from a localized vehicle fire has been observed to produce excessive damage onto highway bridge structural elements including complete collapse of the infrastructure. The occurrence of a fire beneath a bridge can lead to significant economic expense and loss of service even if the bridge does not collapse. The focus of the current research is to assess and evaluate the effect of realistic localized fire exposures from vehicles on the bridge structural integrity and to guide future development of highway bridge design with improved fire resistance.
In this research, the bridge structural element response was predicted through a series of three loosely coupled analyses: fire analysis, thermal analysis, and structural analysis. Two different types of fire modeling methodologies were developed in this research and used to predict the thermo-structural response of bridge structural elements: one to model the non-uniform exposure due to a vehicle fire and another to predict response due to a standard uniform furnace exposure. The vehicle fire scenarios required coupling the computational fluid dynamics (CFD) code Fire Dynamics Simulator (FDS) with Abaqus while the furnace exposure scenarios were all done within Abaqus. Both methodologies were benchmarked against experimental data. Using the developed methodologies, simulations were initially performed to predict the thermo-structural response of a single steel girder-concrete deck composite assembly to different local, non-uniform fires and uniform standard furnace fire exposures. The steel girder-concrete deck composite assembly was selected since it is a common bridge design. Following this, a series of simulations were performed on unprotected highway bridges with multiple steel plate girders and steel tub girders subjected to localized fires. The analyses were used to evaluate the influence of a fire scenario on the bridge element response, identify the factors governing the failure of bridge structural elements subjected to a localized fire exposure, and provide guidance in the design of highway bridge structural elements against fire hazards.
This study demonstrates that girder geometry affected both the dynamics of the fire as well as the heat transfer to the bridge structural elements which resulted in a different structural response for the bridge. A heavy goods vehicle (heat release rate of 200 MW) and tanker fires (heat release rate of 300 MW) were predicted to cause the bridge to fail due to collapse, while smaller fires did not. The geometric features of the plate girders caused the girder elements to be exposed to higher heat fluxes from both sides of the girder resulting in collapse when exposed to a HGV fire. Conversely, the closed feature of the box girder does not allow the interior surfaces to be in direct contact with the flames and are only exposed to the internal reradiation from surfaces inside the girder. As a result, the single and double lane tub girder highway bridge structure does not fail due to a heavy goods vehicle fire…
Advisors/Committee Members: Lattimer, Brian Y. (committeechair), West, Robert L. (committee member), Huxtable, Scott T. (committee member), Diller, Thomas E. (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: Highway Bridge; Fire; Plate Girder; Tub Girder; Structural Analysis; Coupled Analysis; FDS; ABAQUS
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APA (6th Edition):
Nahid, M. N. (2015). Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/73909
Chicago Manual of Style (16th Edition):
Nahid, Mohammad N. “Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure.” 2015. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/73909.
MLA Handbook (7th Edition):
Nahid, Mohammad N. “Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure.” 2015. Web. 17 Jan 2021.
Vancouver:
Nahid MN. Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure. [Internet] [Doctoral dissertation]. Virginia Tech; 2015. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/73909.
Council of Science Editors:
Nahid MN. Computational Study of Highway Bridges Structural Response Exposed to a Large Fire Exposure. [Doctoral Dissertation]. Virginia Tech; 2015. Available from: http://hdl.handle.net/10919/73909
Virginia Tech
5.
Jones, Brenton Michael.
Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments.
Degree: MS, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/36064
► Column-supported, geosynthetic-reinforced embankments provide effective geotechnical foundations for applications in areas of weak subgrade soils. The system consists of a soil bridging layer with one…
(more)
▼ Column-supported, geosynthetic-reinforced embankments provide effective geotechnical foundations for applications in areas of weak subgrade soils. The system consists of a soil bridging layer with one or more embedded layers of geosynthetic reinforcement supported by driven or deep mixed columnar piles. The geosynthetic promotes load transfer within the bridging layer to the columns, allowing for larger column spacings and varied alignments. This technique is generally used when differential settlements of the embankment or adjacent structures are a concern and to minimize construction time.
Recent increase in the popularity of this composite system has generated the need to further investigate its behavior and soil-structure interaction. Current models of geosynthetics are oversimplified and do not represent the true three-dimensional nature of the material. Such simplifications include treating the geosynthetic as a one-dimensional cable as well as neglecting stress concentrations and pile orientations. In this thesis, a complete three-dimensional analysis of the geosynthetic is performed.
The geosynthetic was modeled as a thin flexible plate in a single square unit cell of the embankment. The principle of minimum potential energy was then applied, utilizing central finite difference equations. Energy components from vertical loading, soil and column support, as well as bending and membrane stiffness of the geosynthetic are considered. Three pile orentation types were implemented: square piles, circular piles, and square piles rotated 45° to the edges of the unit cell. Each of the pile orientations was analyzed using two distinct
parameter sets that are investigated in previously published and ongoing research. Vertical and in-plane deflections, stress resultants, and strains were determined and compared to other geosynthetic models and design guides. Results of each parameter set and pile orientation were also compared to provide design recommendations for geosynthetic-reinforced column-supported embankments.
Advisors/Committee Members: Plaut, Raymond H. (committeechair), Sotelino, Elisa D. (committee member), Filz, George M. (committee member).
Subjects/Keywords: finite difference; pile support; plate; geosynthetic reinforcement
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APA (6th Edition):
Jones, B. M. (2007). Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/36064
Chicago Manual of Style (16th Edition):
Jones, Brenton Michael. “Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments.” 2007. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/36064.
MLA Handbook (7th Edition):
Jones, Brenton Michael. “Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments.” 2007. Web. 17 Jan 2021.
Vancouver:
Jones BM. Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments. [Internet] [Masters thesis]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/36064.
Council of Science Editors:
Jones BM. Three-Dimensional Finite Difference Analysis of Geosynthetic Reinforcement Used in Column-Supported Embankments. [Masters Thesis]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/36064
Virginia Tech
6.
Bapat, Amey Vivek.
Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges.
Degree: MS, Civil Engineering, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/36105
► The present study is part of the Long Term Bridge Performance Program (LTBP) funded by the Federal Highway Administration. The objectives of this program are…
(more)
▼ The present study is part of the Long Term Bridge Performance Program (LTBP) funded by the Federal Highway Administration. The objectives of this program are to create a comprehensive database of quantitative information of the long-term performance of selected pilot bridges and to develop a methodology to assess bridge performance. Finite element (FE) modeling of the pilot bridges is an intrinsic part of the LTBP program and is intended to not only assist with instrumentation decisions, but also to provide further insight into the behavior of these bridges, which cannot be achieved solely from field testing of the bridges. This thesis provides a comprehensive study of a plethora of issues associated with the development of reliable and accurate FE models of bridges.
The first objective of this investigation was to develop reliable finite element models with a variety of levels of refinement and to study the effect of the inclusion of various bridge parameters in the model, such as bridge skew, degree of composite action, thermal gradient and level of support restraint, on the response of bridges. First, the suitability of different modeling techniques and of elements used to model the primary bridge components was assessed using simple models for which analytical solutions are readily available. From these studies, it was concluded that shell elements are adequate to model the bridge deck, and beam and shell elements are both satisfactory to model the bridge girders. From the dynamic analyses of theWildcat Creek River Bridge and the Colquitz River Bridge, flexural modes of vibration were found to be highly sensitive to support restraints and to how the guardrails were modeled and less sensitive to the inclusion of bracing and thermal gradients in the model. The finite element models using extreme boundary conditions were successful in bracketing the field response. The factors identified from these analyses were considered in the analysis of the
Virginia pilot bridge. Different support restraints, and the inclusion of skew and level of composite action in the model had noticeable impact on both the static and dynamic responses of the bridge. The results from these analyses were used to assist with instrumentation decisions prior to field-testing. The developed model will also be used to help researchers further understand the bridgeâ s behavior and to help explain a variety of phenomena observed in the field.
Advisors/Committee Members: Sotelino, Elisa D. (committeechair), Roberts-Wollmann, Carin L. (committee member), Cousins, Thomas E. (committee member).
Subjects/Keywords: Finite Element Analysis; Dynamic; Slab on Girder Bridges; Static
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APA (6th Edition):
Bapat, A. V. (2009). Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/36105
Chicago Manual of Style (16th Edition):
Bapat, Amey Vivek. “Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges.” 2009. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/36105.
MLA Handbook (7th Edition):
Bapat, Amey Vivek. “Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges.” 2009. Web. 17 Jan 2021.
Vancouver:
Bapat AV. Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges. [Internet] [Masters thesis]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/36105.
Council of Science Editors:
Bapat AV. Influence of Bridge Parameters on Finite Element Modeling of Slab on Girder Bridges. [Masters Thesis]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/36105
Virginia Tech
7.
Fonseca, Andrea Esperanza.
Contemporary Network Theory: Concepts and Implications for Transportation Asset Management.
Degree: MS, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/33535
► This thesis proposes a novel working paradigm for transportation infrastructure asset management by viewing the transportation networks as key components (or nodes) of a broader…
(more)
▼ This thesis proposes a novel working paradigm for transportation infrastructure asset management by viewing the transportation networks as key components (or nodes) of a broader network of resources, which includes infrastructure linked with societyâ s ecological, social, and economic systems. An extensive review of network science literature suggested that to understand the behavior of a complex network is imperative to characterize its topology. Consequently, this thesis focused on developing a framework to characterize the topology of the transportation infrastructure systems, and understanding how the unveiling topology can be used for supporting transportation asset management decisions.
The proposed methodology determines whether the transportation infrastructure networks can be modeled as scale-free or exponential networks, using a framework for characterizing the agents of the network, their direct and indirect interactions among each other, and their importance as elements of a complex network, and utilizes these data to support transportation asset management. The methodology consist of seven steps: (1) define the networks of interest; (2) identify their intrinsic components; (3) visualize the identified networks using GIS maps; (4) identify direct and indirect interactions through superposition of the networks; (5) represent the relationship between the nodes and their linkages by frequency diagrams in order to determine the intrinsic topology of the network; (6) illustrate (graphically) the overall transportation infrastructure with the help of GIS; and (7) analyze the TINs from the decision-maker point of view, identifying the elements that are more relevant or need more attention on the network.
The procedure is then implemented in a small network in a localized area (Town of Blacksburg,
Virginia) to show its practicality, and recommendations for further development and mathematical modeling in order to allow its implementation in larger networks are provided. Based on frequency analysis of the nodes and their connectivity, it was concluded that the transportation infrastructure networks in the case study behave as exponential networks. The study showed that the links determine how the infrastructure network grows and that problems like congestion can be addressed by analyzing other factors related with topology, such as speed, unit size, and lane width. The proposed methodology was found to be useful as an asset management tool. Finally, a list of findings and recommendations for further research are presented as opportunities to enhance the management of transportation infrastructure networks.
Advisors/Committee Members: Flintsch, Gerardo W. (committeechair), Sotelino, Elisa D. (committee member), Garvin, Michael J. (committee member).
Subjects/Keywords: Transportation Infrastructure; Asset Management; N
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APA (6th Edition):
Fonseca, A. E. (2007). Contemporary Network Theory: Concepts and Implications for Transportation Asset Management. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33535
Chicago Manual of Style (16th Edition):
Fonseca, Andrea Esperanza. “Contemporary Network Theory: Concepts and Implications for Transportation Asset Management.” 2007. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/33535.
MLA Handbook (7th Edition):
Fonseca, Andrea Esperanza. “Contemporary Network Theory: Concepts and Implications for Transportation Asset Management.” 2007. Web. 17 Jan 2021.
Vancouver:
Fonseca AE. Contemporary Network Theory: Concepts and Implications for Transportation Asset Management. [Internet] [Masters thesis]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/33535.
Council of Science Editors:
Fonseca AE. Contemporary Network Theory: Concepts and Implications for Transportation Asset Management. [Masters Thesis]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/33535
Virginia Tech
8.
Boggs, Joshua Thomas.
The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications.
Degree: MS, Civil Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/32998
► An innovative approach to possible construction or rehabilitation of bridge decks can be found in a bridge construction system called the Sandwich Plate System (SPS).…
(more)
▼ An innovative approach to possible construction or rehabilitation of bridge decks can be found in a bridge construction system called the Sandwich Plate System (SPS). The technology developed and patented by Intelligent Engineering Canada Limited in conjunction with an industry partner, Elastogran GmbH, a member of BASF, may be an effective alternative to traditional bridge rehabilitation techniques.
Although the systemâ s behavior has been studied the connection of the SPS deck to the supporting girders has not been investigated. Two types of connection are presented in this research. The use of a bent plate welded to the SPS deck and subsequently bolted to the supporting girder utilizing slip-critical connections has been utilized in the construction of a SPS bridge. A proposed SPS bridge system utilizes the top flange of the supporting girder welded directly to the SPS deck as the deck-to-girder connection.
The fatigue performance of a deck-to-girder connection utilizing a bent plate welded to the deck and bolted to the supporting girder using slip-critical connections was tested in the
Virginia Tech Materials and Structures Laboratory. The testing concluded that the fatigue performance of the welded and bolted bent plate connection was limited by the weld details and no slip occurred in the slip-critical connections. Finite element modeling of the two types of deck-to-girder connections was also used to determine influence of the connections on the local and global behavior of a SPS bridge system. A comparison of the different connection details showed that the connection utilizing the flange welded directly to the SPS deck significantly reduces the stresses at location of the welds in the connections, but the connection type has a limited influence on the global behavior of a SPS bridge.
Advisors/Committee Members: Sotelino, Elisa D. (committee member), Cousins, Thomas E. (committeecochair), Murray, Thomas M. (committeecochair).
Subjects/Keywords: Weld Stress; Lateral Load Distribution; Sandwich Plate System; Fatigue; Slip-Critical Connection; Composite Bridge Decks
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APA (6th Edition):
Boggs, J. T. (2008). The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32998
Chicago Manual of Style (16th Edition):
Boggs, Joshua Thomas. “The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications.” 2008. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32998.
MLA Handbook (7th Edition):
Boggs, Joshua Thomas. “The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications.” 2008. Web. 17 Jan 2021.
Vancouver:
Boggs JT. The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications. [Internet] [Masters thesis]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32998.
Council of Science Editors:
Boggs JT. The Performance and Behavior of Deck-to-Girder Connections for the Sandwich Plate System (SPS) in Bridge Deck Applications. [Masters Thesis]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/32998
Virginia Tech
9.
Kruep, Stephanie Jean.
Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift.
Degree: MS, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/34122
► This thesis presents the details of a study regarding both the use of linear viscous fluid dampers in controlling the interstory drift in steel moment…
(more)
▼ This thesis presents the details of a study regarding both the use of linear viscous fluid dampers in controlling the interstory drift in steel moment frames, and the use of incremental dynamic analysis as a method of visualizing the behavior of these moment frames when subjected to seismic load effects. Models of three story and nine story steel moment frames were designed to meet typical strength requirements for office buildings in Seattle, Washington. These models were intentionally designed to violate seismic interstory drift restrictions to test the ability of the linear viscous fluid dampers to reduce these drifts to the point of code compliance. Dampers were included in one bay of every story in each model. These devices were used to produce total structural damping ratios of 5%, 10%, 20%, and 30% of critical. Undamped, traditional stiffness controlled models of both three stories and nine stories were also created for comparison purposes. Incremental dynamic analysis was used to subject these models to ten ground motions, each scaled to twenty incremental levels. Two new computer applications were written to facilitate this process. The results of these analyses were studied to determine if the linear viscous fluid dampers were able to cause compliance with codified drift limits. Also, incremental dynamic analysis plots were created to examine the effects of the dampers on structural behavior as damping increased from inherent to 30% of critical. It was found that including linear viscous fluid dampers in steel moment frame design can satisfactorily control interstory drift, and incremental dynamic analysis is a beneficial tool in visualizing dynamic structural behavior.
Advisors/Committee Members: Charney, Finley A. (committeechair), Easterling, William Samuel (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: steel structures; seismic design; damping; drift; incremental dynamic analysis; passive energy; structural dynamics
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APA (6th Edition):
Kruep, S. J. (2007). Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34122
Chicago Manual of Style (16th Edition):
Kruep, Stephanie Jean. “Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift.” 2007. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/34122.
MLA Handbook (7th Edition):
Kruep, Stephanie Jean. “Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift.” 2007. Web. 17 Jan 2021.
Vancouver:
Kruep SJ. Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift. [Internet] [Masters thesis]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/34122.
Council of Science Editors:
Kruep SJ. Using Incremental Dynamic Analysis to Visualize the Effects of Viscous Fluid Dampers on Steel Moment Frame Drift. [Masters Thesis]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/34122
Virginia Tech
10.
Jeffers, Ann E.
Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts.
Degree: MS, Civil Engineering, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/36299
► The purpose of this research is to analyze a new type of vibration isolator consisting of two pre-bent struts which are clamped at both ends…
(more)
▼ The purpose of this research is to analyze a new type of vibration isolator consisting of two pre-bent struts which are clamped at both ends and intermediately bonded with a viscoelastic filler. The proposed isolation device has the ability to support a relatively large static load with little deflection and offers a low axial resistance under dynamic excitation, making it ideal for isolating vertical vibrations. In this research, four of these vibration isolators are used to support a rigid, square plate. The symmetric case is analyzed first. Then the plate has a center of mass which is located at some distance from the geometric center of the plate. When the system is subjected to vertical harmonic base excitations, this eccentric weight introduces rotational as well as vertical motions of the plate. This research will investigate the effects of various eccentricities on the efficiency of the vibration isolators in the configuration described.
The displacement transmissibility will be the measure of the isolators' effectiveness at mitigating vibrations transmitted from the base to the rigid plate. For each case, the nonlinear equilibrium equations and the governing equations of motion for small vibrations about equilibrium are numerically solved, and the transmissibility is calculated and plotted over a wide range of frequencies. These plots are used to recognize ranges of frequencies for which isolation is achieved and frequencies at which resonance occurs in the system. At the resonant frequencies, the physical behavior of the system is analyzed to determine the types of vibration modes which occur in the system. A free vibration analysis is also performed to obtain a better understanding of resonances in the system.
Advisors/Committee Members: Plaut, Raymond H. (committeechair), Rojiani, Kamal B. (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: vibration isolation; buckled structures; dynamic response
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APA (6th Edition):
Jeffers, A. E. (2005). Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/36299
Chicago Manual of Style (16th Edition):
Jeffers, Ann E. “Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts.” 2005. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/36299.
MLA Handbook (7th Edition):
Jeffers, Ann E. “Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts.” 2005. Web. 17 Jan 2021.
Vancouver:
Jeffers AE. Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/36299.
Council of Science Editors:
Jeffers AE. Vibration Isolation of a Horizontal Rigid Plate Supported by Pre-bent Struts. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/36299
Virginia Tech
11.
Timko, Paul Daniel.
Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads.
Degree: MS, Civil Engineering, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/42527
► The research summarized the experimental analysis and finite element modeling of the lateral and rotational response of unbraced wood composite I-joists to worker loads. All…
(more)
▼ The research summarized the experimental analysis and finite element modeling of the lateral and rotational response of unbraced wood composite I-joists to worker loads. All experimentation and modeling was conducted on simply supported I-joists varying from 11-7/8 inches to 14 inches in depth and 20 feet to 24 feet in length. I-joists were subjected to static and dynamic loads. The deflections of the top and bottom flanges, as well as the rotation, were measured or calculated at both one-half and one-quarter the span length. The overall goal of this project is to accurately model the lateral and rotational displacements caused by human load effects.
I-joists were first tested statically by subjecting each joist to a three point bending test, free from all lateral restraints. This test was necessary to prove that the performance of the joists was repeatable. Lateral and rotational stiffness of the joist were calculated at one-half and one-quarter of the span length. The static experimental tests results were statistically analyzed using an analysis of variance (ANOVA) test. The results from this analysis indicated no difference between repetitions of the same joist; however, the test did indicate that there was a significant difference between joists of the same manufacture and size. Dynamic testing was then conducted. Dynamic loads were induced by having test subjects traverse each I-joist. The resulting loads induced at the top and bottom flanges were recorded for use in the finite element model. The lateral deflections and induced loads were compared to the static weight of the test subject and analyzed with an ANOVA test. The results indicated an increase in both the induced load and resulting deflection with an increase in weight. The analysis also indicated an increase in load and deflection with a decrease in lateral and rotational joist stiffness.
The recorded load values from the dynamic test were used as inputs into a finite element model. The resulting lateral deflections of the midpoint and quarter point were generated. The rotation of the beam was calculated from the difference between the top and bottom flange. Experimental results and finite element model results were compared by calculating a running average of the error between the acquired data and the finite element model. The model was said to be valid until the average model error reached 10 percent of the maximum acquired test value. All six deflection readings were analyzed in this manner. The percent of beam at which the model no long represented the test data was determined for each data set. This point was averaged across all deflection readings of similar joists and across all data sets of the same joist type. The model predicted the 20 foot long 11-7/8 and 14 inch deep joists until 54.5 percent and 51.2 percent, respectively, of the beam completed by the test subject. However, the 24 foot long 11-7/8 inch deep joist was only accurate to 31.2 percent of the beam completed by the test subject.
Differences in peak…
Advisors/Committee Members: Nussbaum, Maury A. (committee member), Sotelino, Elisa D. (committeecochair), Hindman, Daniel P. (committeecochair).
Subjects/Keywords: Finite Element; Composite Wood I-joist; Construction Loads; Lateral Torsional Buckling
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APA (6th Edition):
Timko, P. D. (2009). Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/42527
Chicago Manual of Style (16th Edition):
Timko, Paul Daniel. “Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads.” 2009. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/42527.
MLA Handbook (7th Edition):
Timko, Paul Daniel. “Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads.” 2009. Web. 17 Jan 2021.
Vancouver:
Timko PD. Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads. [Internet] [Masters thesis]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/42527.
Council of Science Editors:
Timko PD. Finite Element Analysis of Unbraced Structural Wood I-Joists Under Construction Loads. [Masters Thesis]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/42527
Virginia Tech
12.
Hensley, Gregory Martin.
Finite Element Analysis of the Seismic Behavior of Guyed Masts.
Degree: MS, Civil Engineering, 2005, Virginia Tech
URL: http://hdl.handle.net/10919/33900
► Seismic design of guyed masts, commonly used in the broadcasting and telecommunications industries, has not been fully addressed in the United States. There is no…
(more)
▼ Seismic design of guyed masts, commonly used in the broadcasting and telecommunications industries, has not been fully addressed in the United States. There is no specific design code, and only a limited amount of research has been reported on the subject. This research investigates the behavior of guyed masts incorporating synthetic ropes as guys, with a particular focus on the effect of snap loads on the mast behavior. This is the third phase of a multi-stage project aimed at analyzing the potential for Snapping-Cable Energy Dissipators (SCEDs) to minimize lateral response in structures.
A finite element model of a 120-m-tall guyed mast was developed with the commercial program ABAQUS. The three-dimensional behavior of the mast was observed when subjected to two ground motion records: Northridge and El Centro. Three orthogonal earthquake components were input, two horizontal and one vertical. A series of parametric studies was conducted to determine the sensitivity of the response to guy pretension, which is a measure of the potential slackness in the guys during response. Additionally, the studies examined the effects of guy stiffness, mast properties, and directionality of input motion.
Deflections, bending moments, guy tensions, and base shears were examined. The results were used to characterize the trends in the structural response of guyed masts. The level of slackness in the guys changed the behavior, and the lessons learned will be used to continue research on the application of SCEDs in structures.
Advisors/Committee Members: Plaut, Raymond H. (committeechair), Sotelino, Elisa D. (committee member), Roberts-Wollmann, Carin L. (committee member).
Subjects/Keywords: Mast; Finite Element; Synthetic Fiber Ropes; Seismic Response; Guy Wires
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APA (6th Edition):
Hensley, G. M. (2005). Finite Element Analysis of the Seismic Behavior of Guyed Masts. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/33900
Chicago Manual of Style (16th Edition):
Hensley, Gregory Martin. “Finite Element Analysis of the Seismic Behavior of Guyed Masts.” 2005. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/33900.
MLA Handbook (7th Edition):
Hensley, Gregory Martin. “Finite Element Analysis of the Seismic Behavior of Guyed Masts.” 2005. Web. 17 Jan 2021.
Vancouver:
Hensley GM. Finite Element Analysis of the Seismic Behavior of Guyed Masts. [Internet] [Masters thesis]. Virginia Tech; 2005. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/33900.
Council of Science Editors:
Hensley GM. Finite Element Analysis of the Seismic Behavior of Guyed Masts. [Masters Thesis]. Virginia Tech; 2005. Available from: http://hdl.handle.net/10919/33900
Virginia Tech
13.
Himebaugh, Anne Katherine.
Finite Element Analysis of Insulated Railroad Joints.
Degree: MS, Civil Engineering, 2006, Virginia Tech
URL: http://hdl.handle.net/10919/36159
► In recent years, the lifetime of an insulated railroad joint in the field has decreased due to increasing wheel loads. The goal of this research…
(more)
▼ In recent years, the lifetime of an insulated railroad joint in the field has decreased due to increasing wheel loads. The goal of this research is to investigate possible changes in insulated rail joint design in order to improve the performance of the insulated joint. The finite element program ABAQUS is used to model the supported butt joint. In this model, the rail, joint bars, epoxy, and ties surrounding the joint are modeled using solid elements. The remaining ties are modeled as an elastic foundation. The rail is subjected to a tensile load, as well as a vertical wheel load that is applied to the rail using Hertz contact theory.
Parametric studies are performed by varying the tie width, joint bar length, and joint bar dimensions. Two different wheel load locations are also investigated: centered about the end post, and halfway between the tie under the end post and the tie just to the left of the end post.
The vertical displacement of the rail and insulated joint is one measure used to determine the effect of the parameters on the insulated joint. However, since the most common cause of failure in insulated rail joints is the debonding of the epoxy, this research also focuses on the stresses present in the epoxy when the joint is subjected to a static wheel load. The two out-of-plane shear stresses as well as the normal peel stress are used to compare the various designs of the joint.
Advisors/Committee Members: Plaut, Raymond H. (committeechair), Sotelino, Elisa D. (committee member), Dillard, David A. (committee member).
Subjects/Keywords: Hertz Contact; Elastic Foundation; Finite Element; Insulated Railroad Joint
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APA (6th Edition):
Himebaugh, A. K. (2006). Finite Element Analysis of Insulated Railroad Joints. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/36159
Chicago Manual of Style (16th Edition):
Himebaugh, Anne Katherine. “Finite Element Analysis of Insulated Railroad Joints.” 2006. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/36159.
MLA Handbook (7th Edition):
Himebaugh, Anne Katherine. “Finite Element Analysis of Insulated Railroad Joints.” 2006. Web. 17 Jan 2021.
Vancouver:
Himebaugh AK. Finite Element Analysis of Insulated Railroad Joints. [Internet] [Masters thesis]. Virginia Tech; 2006. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/36159.
Council of Science Editors:
Himebaugh AK. Finite Element Analysis of Insulated Railroad Joints. [Masters Thesis]. Virginia Tech; 2006. Available from: http://hdl.handle.net/10919/36159
Virginia Tech
14.
Collins, William Norfleet.
Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66.
Degree: MS, Civil Engineering, 2010, Virginia Tech
URL: http://hdl.handle.net/10919/34364
► As aging bridges around the United States begin to near the end of their service lives, more funding must be allocated for their rehabilitation or…
(more)
▼ As aging bridges around the United States begin to near the end of their service lives,
more funding must be allocated for their rehabilitation or replacement. The Federal Highway
Administrationâ s (FHWA) Long-Term Bridge Performance (LTBP) Program has been developed
to help bridge stakeholders make the best decisions concerning the allocation of these funds.
This is done through the use of high quality data obtained through numerous testing processes.
As part of the LTBP Pilot Program, researchers have performed live load tests on the
U.S. Route 15 Southbound bridge over Interstate-66. The main performance and behavior
characteristics focused on are service strain and deflection, wheel load distribution, dynamic load
allowance, and rotational behavior of bridge bearings.
Data from this test will be used as a tool in developing and refining a plan for long-term
bridge monitoring. This includes identifying the primarily loaded girders and their expected
range of response under ambient traffic conditions. Information obtained from this test will also
aid in the refinement of finite element models by offering insight into the performance of
individual bridge components, as well as overall global behavior. Finally, the methods and
results of this test have been documented to allow for comparison with future testing of this
bridge, which will yield information concerning the changes in bridge behavior over time.
Advisors/Committee Members: Cousins, Thomas E. (committeechair), Roberts-Wollmann, Carin L. (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: wheel load distribution; Long-Term Bridge Performance Program; Federal Highway Administration; Live load test; expansion joints; bridge bearings; dynamic load allowance; neutral axis
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APA (6th Edition):
Collins, W. N. (2010). Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34364
Chicago Manual of Style (16th Edition):
Collins, William Norfleet. “Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66.” 2010. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/34364.
MLA Handbook (7th Edition):
Collins, William Norfleet. “Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66.” 2010. Web. 17 Jan 2021.
Vancouver:
Collins WN. Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66. [Internet] [Masters thesis]. Virginia Tech; 2010. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/34364.
Council of Science Editors:
Collins WN. Live Load Testing and Analysis of the Southbound Span of U.S. Route 15 over Interstate-66. [Masters Thesis]. Virginia Tech; 2010. Available from: http://hdl.handle.net/10919/34364
Virginia Tech
15.
Baldwin Metzger, Kirsten Anne.
Experimental Verification of a New Single Plate Shear Connection Design Model.
Degree: MS, Civil Engineering, 2006, Virginia Tech
URL: http://hdl.handle.net/10919/32576
► Single plate shear connections are designed to have sufficient strength to resist the shear force and moment transferred from the beam. The connections must also…
(more)
▼ Single plate shear connections are designed to have sufficient strength to resist the shear force and moment transferred from the beam. The connections must also provide sufficient ductility to allow the beam end to rotate freely. In the United States the current recommended design method is found in the AISC 13th Edition Steel Construction Manual (2005b). The limited experimental work which led to the current method necessitated additional single plate shear connection investigations.
This paper summarizes the results and analysis of eight full scale single plate shear connections tested at
Virginia Polytechnic Institute and State University. The test setup consisted of a test beam attached to a test column with a single plate shear connection at one end and supported by a roller at the other end. The single plate was welded to the column flange and bolted to the beam web. Load was applied to the test beam at third points until failure of the connection or test beam.
The current design method used in the United States was examined with respect to the connection tests performed. In particular, the ultimate shear strength and the rotational capacity were investigated. Suggestions are made regarding changes to the method and further research.
Advisors/Committee Members: Murray, Thomas M. (committeechair), Sotelino, Elisa D. (committee member), Easterling, William Samuel (committee member).
Subjects/Keywords: Connections; Shear Tabs; Bolts; Steel
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APA (6th Edition):
Baldwin Metzger, K. A. (2006). Experimental Verification of a New Single Plate Shear Connection Design Model. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32576
Chicago Manual of Style (16th Edition):
Baldwin Metzger, Kirsten Anne. “Experimental Verification of a New Single Plate Shear Connection Design Model.” 2006. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32576.
MLA Handbook (7th Edition):
Baldwin Metzger, Kirsten Anne. “Experimental Verification of a New Single Plate Shear Connection Design Model.” 2006. Web. 17 Jan 2021.
Vancouver:
Baldwin Metzger KA. Experimental Verification of a New Single Plate Shear Connection Design Model. [Internet] [Masters thesis]. Virginia Tech; 2006. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32576.
Council of Science Editors:
Baldwin Metzger KA. Experimental Verification of a New Single Plate Shear Connection Design Model. [Masters Thesis]. Virginia Tech; 2006. Available from: http://hdl.handle.net/10919/32576
Virginia Tech
16.
Hardyniec, Andrew B.
Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge.
Degree: MS, Civil Engineering, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/34806
► Created in response to the aging infrastructure in the United States, the Long Term Bridge Performance Program (LTBPP) under the Federal Highway Administration (FHWA) proposes…
(more)
▼ Created in response to the aging infrastructure in the United States, the Long Term Bridge Performance Program (LTBPP) under the Federal Highway Administration (FHWA) proposes to assess the long-term performance of representative bridges through nondestructive evaluation (NDE) techniques and visual inspection. For consistency, a set of guidelines is needed to define the procedures for testing each bridge. The NDE techniques involve dynamic testing, and the protocol for this testing has yet to be finalized.
To evaluate the dynamic testing guidelines, a 103 ft single-span, simply supported highway bridge was dynamically tested. The test bridge was characterized by a skew of 34° and superelevation around 4%. Forced vibration testing involved an impact hammer with accelerometers measuring the response. Resonant frequencies were identified from the data by picking peaks from the magnitudes of the frequency response functions (FRF). Eleven modes were identified with frequencies ranging from 2.75 Hz to 22.5 Hz. Mode shapes associated with each mode were constructed using the imaginary components of the FRFs. The half-power bandwidth method was used to estimate the damping for each mode, with values ranging from 1% to 5% of critical damping.
Finite element (FE) models of the bridge were constructed in the commercial FE software Abaqus. The effects of adding and removing superelevation and skew, varying mesh refinement, and changing boundary conditions on modal parameters were thoroughly investigated. FE models were compared to the experimental results by directly comparing frequencies and using the modal assurance criterion to compare mode shapes. Support conditions of the actual structure were bounded using the results of the comparison.
Much insight was gained about forced vibration testing as applied to a full-scale bridge. The spectral resolution of the data proved to limit the accuracy and confidence of detecting closely-spaced modes and calculating damping estimates. Also, a more controlled method of exciting the structure was desired, such as using a shaker with a known input. Resonant frequencies of the FE models were sensitive to changes in boundary conditions, with some frequencies doubling. Both changes in boundary conditions and including skew and superelevation noticeably affected the mode shapes. When compared to the experimental results, the models with idealized roller and pin boundary conditions provided the best correlations based on resonant frequencies and mode shapes.
Advisors/Committee Members: Sotelino, Elisa D. (committeechair), Roberts-Wollmann, Carin L. (committee member), Cousins, Thomas E. (committee member).
Subjects/Keywords: Finite Element Method; Modal; Dynamic; Bridge; Field Testing
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APA (6th Edition):
Hardyniec, A. B. (2009). Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/34806
Chicago Manual of Style (16th Edition):
Hardyniec, Andrew B. “Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge.” 2009. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/34806.
MLA Handbook (7th Edition):
Hardyniec, Andrew B. “Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge.” 2009. Web. 17 Jan 2021.
Vancouver:
Hardyniec AB. Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge. [Internet] [Masters thesis]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/34806.
Council of Science Editors:
Hardyniec AB. Dynamic Testing and Modeling of a Superelevated Skewed Highway Bridge. [Masters Thesis]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/34806
Virginia Tech
17.
Venturella, Michael Anthony.
Modal Analysis of the Ice-Structure Interaction Problem.
Degree: MS, Aerospace and Ocean Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/31749
► In the present study, the author builds upon the single degree of freedom ice-structure interaction model initially proposed by Matlock, et al. (1969, 1971). The…
(more)
▼ In the present study, the author builds upon the single degree of freedom ice-structure interaction model initially proposed by Matlock, et al. (1969, 1971). The model created by Matlock, et al. (1969, 1971), assumed that the primary response of the structure would be in its fundamental mode of vibration. In order to glean a greater physical understanding of ice-structure interaction phenomena, it was critical that this study set out to develop a multi-mode forced response for the pier when a moving ice floe makes contact at a specific vertical pier location. Modal analysis is used in which the response of each mode is superposed to find the full modal response of the entire length of a pier subject to incremental ice loading. This incremental ice loading includes ice fracture points as well as loss of contact between ice and structure. In this model, the physical system is a bottom supported pier modeled as a cantilever beam. The frequencies at which vibration naturally occurs, and the mode shapes which the vibrating pier assumes, are properties which can be determined analytically and thus a more precise picture of pier vibration under ice loading is presented. Realistic conditions such as ice accumulation on the pier modeled as a point mass and uncertainties in the ice characteristics are introduced in order to provide a stochastic response. The impact of number of modes in modeling is studied as well as dynamics due to fluctuations of ice impact height as a result of typical tidal fluctuations. A Poincaré based analysis following on the research of Karr, et al. (1992) is employed to identify any periodic behavior of the system response. Recurrence plotting is also utilized to further define any existing structure of the ice-structure interaction time series for low and high speed floes. The intention of this work is to provide a foundation for future research coupling multiple piers and connecting structure for a comprehensive ice-wind-structural dynamics model.
Advisors/Committee Members: Sotelino, Elisa D. (committee member), McCue-Weil, Leigh S. (committeecochair), Patil, Mayuresh J. (committeecochair).
Subjects/Keywords: ice-structure interaction; modal analysis; Poincaré mapping; recurrence plot
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APA (6th Edition):
Venturella, M. A. (2008). Modal Analysis of the Ice-Structure Interaction Problem. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/31749
Chicago Manual of Style (16th Edition):
Venturella, Michael Anthony. “Modal Analysis of the Ice-Structure Interaction Problem.” 2008. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/31749.
MLA Handbook (7th Edition):
Venturella, Michael Anthony. “Modal Analysis of the Ice-Structure Interaction Problem.” 2008. Web. 17 Jan 2021.
Vancouver:
Venturella MA. Modal Analysis of the Ice-Structure Interaction Problem. [Internet] [Masters thesis]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/31749.
Council of Science Editors:
Venturella MA. Modal Analysis of the Ice-Structure Interaction Problem. [Masters Thesis]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/31749
Virginia Tech
18.
Koch, Stephanie Ann.
Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm.
Degree: MS, Civil Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/32114
► This research document focuses on prestressed PCBT girders made composite with a cast-in-place concrete deck and continuous over several spans through the use of…
(more)
▼
This research document focuses on prestressed PCBT girders made composite with a cast-in-place concrete deck and continuous over several spans through the use of continuity diaphragms. The current design procedure in AASHTO states that a continuity diaphragm is considered to be fully effective if a compressive stress develops in the bottom of the diaphragm when the superimposed permanent load, settlement, creep, shrinkage, 50 percent live load, and temperature gradient are summed, or if the girders are stored at least 90 days when continuity is established. It is more economical to store girders for fewer days, so it is important to know the minimum number of days that girders must be stored to satisfy AASHTO requirements.
In 2005, Charles Newhouse developed the positive moment diaphragm reinforcement detail that is currently being adopted by VDOT. This thesis concludes that Newhouseâ s detail, four No. 6 bars bent 180° and extended into the diaphragm, is adequate for all girders except for the PCBT-77, PCBT-85, and the PCBT-93 when the girders are stored for a minimum of 90 days. It is recommended that two additional bent strands be extended into the continuity diaphragm for these three girder sizes.
It was also concluded that about half of the cases result in a significant reduction in the minimum number of storage days if the designer is willing to perform a detailed analysis. The other half of the cases must be stored for 90 days because the total moment in the diaphragm will never become negative and satisfy the AASHTO requirement. In general, narrower girder spacing and higher concrete compressive strength results in shorter required storage duration. The PCA Method was used in this analysis with the updated AASHTO LRFD creep, shrinkage, and prestress loss models. A recommended quick check is to sum the thermal, composite dead load, and half of the live load restraint moments. The girder must be stored 90 days if that sum is positive, and a more detailed time-dependent analysis would result in a shorter than 90 day storage period if that sum is negative.
Advisors/Committee Members: Roberts-Wollmann, Carin L. (committeechair), Cousins, Thomas E. (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: Restraint Moment; PCA Method; Diaphragm; PCBT Girders
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APA (6th Edition):
Koch, S. A. (2008). Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32114
Chicago Manual of Style (16th Edition):
Koch, Stephanie Ann. “Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm.” 2008. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32114.
MLA Handbook (7th Edition):
Koch, Stephanie Ann. “Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm.” 2008. Web. 17 Jan 2021.
Vancouver:
Koch SA. Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm. [Internet] [Masters thesis]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32114.
Council of Science Editors:
Koch SA. Prestressed PCBT Girders Made Continuous and Composite with a Cast-in-place Deck and Diaphragm. [Masters Thesis]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/32114
Virginia Tech
19.
Halvordson, Kyle Arthur.
Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment.
Degree: MS, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/36127
► Pile-supported geogrid-reinforced embankments are an exciting new foundation system that is utilized when sites are limited by a soft soil or clay. In this system,…
(more)
▼ Pile-supported geogrid-reinforced embankments are an exciting new foundation system that is utilized when sites are limited by a soft soil or clay. In this system, an embankment is supported by a bridging layer, consisting of granular fill and one or multiple layers of geogrid reinforcement. The bridging layer transfers the load to piles that have been driven into the soft soil or clay. The load from the embankment induces large deformations in the geogrid reinforcement, causing tensile forces in the ribs of the geogrid. Many of the current methods used to design geogrid reinforcement for this system simplify the approach by assuming that the reinforcement has a parabolic deformed shape. The purpose of this thesis is to thoroughly examine the behavior of the geogrid in a pile-supported embankment system, in an effort to determine the accuracy of the parabolic deformed shape, and identify the most important parameters that affect reinforcement design.
The geogrid was analyzed using a three-dimensional model that included a cable net to represent the geogrid and linear springs to represent the soil underneath the geogrid. A larger pressure was applied to the geogrid regions that are directly above the pile caps so that arching effects could be considered, and the stiffness of the springs on top of the pile were stiffer to account for the thin layer of soil between the geogrid and the pile cap. A Mathematica algorithm was used to solve this model using the minimization of energy method.
The results were compared to another model of this system that used a membrane to represent the geosynthetic reinforcement. Additionally, the maximum strain was compared to the strain obtained from a geosynthetic reinforcement design formula. A parametric study was performed using the Mathematica algorithm by varying the pile width, embankment pressure applied to the soil, embankment pressure applied to the pile, stiffness of the soil, stiffness of the soil on top of the pile, stiffness of the geogrid, geogrid orientation, rotational stiffness of the geogrid, and the layers of geogrid reinforcement.
Advisors/Committee Members: Plaut, Raymond H. (committeechair), Filz, George M. (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: Cable Net; Geosynthetic Reinforcement; Geogrid; Minimization of Energy
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APA (6th Edition):
Halvordson, K. A. (2007). Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/36127
Chicago Manual of Style (16th Edition):
Halvordson, Kyle Arthur. “Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment.” 2007. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/36127.
MLA Handbook (7th Edition):
Halvordson, Kyle Arthur. “Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment.” 2007. Web. 17 Jan 2021.
Vancouver:
Halvordson KA. Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment. [Internet] [Masters thesis]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/36127.
Council of Science Editors:
Halvordson KA. Three-Dimensional Analysis of Geogrid Reinforcement used in a Pile-Supported Embankment. [Masters Thesis]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/36127
Virginia Tech
20.
Hickey, Lucas James.
Model Validation for a Steel Deck Truss Bridge over the New River.
Degree: MS, Civil Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/32154
► This thesis presents the methods utilized to model a steel deck truss bridge over the New River in Hillsville, Virginia. These methods were evaluated…
(more)
▼ This thesis presents the methods utilized to model a steel deck truss bridge over the New River in Hillsville,
Virginia. These methods were evaluated by comparing analytical results with data recorded from 14 members during live load testing. The research presented herein is part of a larger endeavor to understand the structural behavior and collapse mechanism of the erstwhile I-35W bridge in Minneapolis, MN. Objectives accomplished toward this end include investigation of lacing effects on built up member strain detection, live load testing of a steel truss bridge, and evaluating modeling techniques in comparison to recorded data.
Before any live load testing could be performed, it was necessary to confirm an acceptable strain gage layout for measuring member strains. The effect of riveted lacing in built-up members was investigated by constructing a two-thirds mockup of a typical bridge member. The mockup was then instrumented with strain gages and subjected to known strains in order to determine the most effective strain gage arrangement. Testing analysis concluded that for a built up member consisting of laced channels, one strain gage installed on the middle of the extreme fiber of each channelâ s flanges was sufficient. Thus, laced members on the bridge were mounted with four strain gages each.
Data from live loads were obtained by loading two trucks to 25 tons each. Trucks were positioned at eight locations on the bridge in four different relative truck positions. Data were recorded continuously and reduced to member forces for model validation comparisons. Deflections at selected truss nodes were also recorded for model validation purposes.
The model validation process began by developing four simple truss models, each reflecting different expected restraint conditions, in the hopes of bracketing data from recorded results. Models were refined to frames, and then frames including floor beams and stringers for greater accuracy. The final, most accurate model was selected and used for a failure analysis. This model showed where the minimum amount of load could be applied in order to learn about the bridgeâ s failure behavior, for a test to be conducted at a later time.
Advisors/Committee Members: Roberts-Wollmann, Carin L. (committeechair), Sotelino, Elisa D. (committee member), Cousins, Thomas E. (committee member).
Subjects/Keywords: model validation; lacing of built-up members; steel deck truss; sensitivity analysis
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APA (6th Edition):
Hickey, L. J. (2008). Model Validation for a Steel Deck Truss Bridge over the New River. (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/32154
Chicago Manual of Style (16th Edition):
Hickey, Lucas James. “Model Validation for a Steel Deck Truss Bridge over the New River.” 2008. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/32154.
MLA Handbook (7th Edition):
Hickey, Lucas James. “Model Validation for a Steel Deck Truss Bridge over the New River.” 2008. Web. 17 Jan 2021.
Vancouver:
Hickey LJ. Model Validation for a Steel Deck Truss Bridge over the New River. [Internet] [Masters thesis]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/32154.
Council of Science Editors:
Hickey LJ. Model Validation for a Steel Deck Truss Bridge over the New River. [Masters Thesis]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/32154
Virginia Tech
21.
Woodworth, Michael Allen.
Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC).
Degree: MS, Civil Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/35608
► Ultra High Performance Concrete (UHPC) is a class of cementitious materials that share similar characteristics including very large compressive strengths, tensile strength greater than conventional…
(more)
▼ Ultra High Performance Concrete (UHPC) is a class of cementitious materials that share similar characteristics including very large compressive strengths, tensile strength greater than conventional concrete and high durability. The material consists of finely graded cementitious particles and aggregates to develop a durable dense matrix. The addition of steel fibers increases ductility such that the material develops usable tensile strength. The durability and strength of UHPC makes it a desirable material for the production of highway bridge girders. However, UHPCâ s unique constitutive materials make it more expensive than conventional concrete. The cost and lack of appropriate design guidelines has limited its introduction into bridge products.
The investigation presented in this thesis developed several optimization formulations to determine a suitable bridge girder shape for use with UHPC. The goal of this optimization was to develop a methodology of using UHPC in highway bridge designs that was cost competitive with conventional concrete solutions. Several surveys and field visits were performed to identify the important aspects of girder fabrication. Optimizations were formulated to develop optimized girder cross sections and full bridge design configurations that utilize UHPC. The results showed that for spans greater than 90 ft UHPC used in the proposed girder shape was more economical than conventional girders. The optimizations and surveys resulted in the development of a proposed method to utilize UHPC in highway bridges utilizing existing girder shapes and formwork. The proposed method consists of three simple calculations to transform an initial conventional design to an initial design using modified UHPC girders.
Advisors/Committee Members: Roberts-Wollmann, Carin L. (committeechair), Sotelino, Elisa D. (committee member), Cousins, Thomas E. (committee member).
Subjects/Keywords: Bridge; Girder; UHPC; Ultra High Performance Concrete; Optimization
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APA (6th Edition):
Woodworth, M. A. (2008). Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC). (Masters Thesis). Virginia Tech. Retrieved from http://hdl.handle.net/10919/35608
Chicago Manual of Style (16th Edition):
Woodworth, Michael Allen. “Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC).” 2008. Masters Thesis, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/35608.
MLA Handbook (7th Edition):
Woodworth, Michael Allen. “Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC).” 2008. Web. 17 Jan 2021.
Vancouver:
Woodworth MA. Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC). [Internet] [Masters thesis]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/35608.
Council of Science Editors:
Woodworth MA. Optimization of Highway Bridge Girders for Use with Ultra-High Performance Concrete (UHPC). [Masters Thesis]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/35608
Virginia Tech
22.
Carroll, James Christopher.
Grade 300 Prestressing Strand and the Effect of Vertical Casting Position.
Degree: PhD, Civil Engineering, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/28806
► The purpose of this study was to investigate the influence an increase in strand strength and the effect the as-cast vertical location had on transfer…
(more)
▼ The purpose of this study was to investigate the influence an increase in strand strength and the effect the as-cast vertical location had on transfer length, development length, and flexural strength and to resolve the discrepancies regarding the definition of the top-bar/strand effect. Two types of test specimens were fabricated and tested investigating each respective item. The increase in strand strength was found to influence transfer length, development length, and flexural strength, while the as-cast vertical location was only found to influence transfer length, and in turn development length. Contrary to the historical definition, the top-bar/strand effect was found to be more dependent on the amount of concrete cast above the strand than the amount below it, with transfer lengths showing a steady increase with a decrease in the amount of concrete cast above the strand. As a result of the findings of this study, a new transfer length equation was proposed and a previously proposed flexural bond length equation was recommended for use in lieu of the current code provisions. The current equations for flexural strength were found to give adequate estimates for flexural strength, although a decrease in ductility was noted.
Advisors/Committee Members: Sotelino, Elisa D. (committee member), Wang, Linbing (committee member), Cousins, Thomas E. (committeecochair), Roberts-Wollmann, Carin L. (committeecochair).
Subjects/Keywords: Flexural strength; Top-strand effect; Bond; Development length; Prestressed concrete; Transfer length; Grade 300 strand
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APA (6th Edition):
Carroll, J. C. (2009). Grade 300 Prestressing Strand and the Effect of Vertical Casting Position. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28806
Chicago Manual of Style (16th Edition):
Carroll, James Christopher. “Grade 300 Prestressing Strand and the Effect of Vertical Casting Position.” 2009. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/28806.
MLA Handbook (7th Edition):
Carroll, James Christopher. “Grade 300 Prestressing Strand and the Effect of Vertical Casting Position.” 2009. Web. 17 Jan 2021.
Vancouver:
Carroll JC. Grade 300 Prestressing Strand and the Effect of Vertical Casting Position. [Internet] [Doctoral dissertation]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/28806.
Council of Science Editors:
Carroll JC. Grade 300 Prestressing Strand and the Effect of Vertical Casting Position. [Doctoral Dissertation]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/28806
Virginia Tech
23.
Lu, Yang.
Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface.
Degree: PhD, Civil Engineering, 2010, Virginia Tech
URL: http://hdl.handle.net/10919/27540
► This dissertation is dedicated to develop models and methods to bridge atomistic and continuum scales of deformation processes in asphalt-aggregate interfacial composite materials systems. The…
(more)
▼ This dissertation is dedicated to develop models and methods to bridge atomistic and continuum scales of deformation processes in asphalt-aggregate interfacial composite materials systems. The deformation and failure behaviors, e.g. nanoscale strength, deformation, stiffness, and adhesion/cohesion at asphalt-aggregate interfaces are all evaluated by means of atomistic simulations. The atomistic modeling approach is employed to simulate mechanical properties, which is connected by their common dependence on the nanoscale bonding and their sensitive dependences on mechanics and moisture sensitivity. Specifically, CVFF-aug forcefield is employed in the atomistic calculations to study the fundamental failure processes that appear at the interface as a result of a mechanical deformation. There are five primary aspects to this dissertation.
First, the multiscale features of asphalt concrete materials are characterized by using nanoscale characterization & fabrication devices, e.g. High Resolution Optical Microscope (HROM), Environmental Scanning Electron Microscope (ESEM), Transmission Electron Microscope (TEM), Focused Ion Beam (FIB), and Atomistic Force Microscope (AFM).
Second, based on the multiscale devices characterization of the interfaces, a 2-layer atomistic bitumen-rock interface structure is constructed. Interface structure evolution under uniaxial tension is performed with various deformation rates. Comparison is made between both theoretical and experimental characterizations of interface configuration. Molecular dynamics (MD) simulations are used to investigate potential relationships between interface structure and morphology. Influences of deformation rate and temperature factors are discussed in terms of interface region stress-strain relation and loading time duration.
Third, molecular dynamics simulations are also performed to provide a characterization of atomic scale mechanical behaviors for a 3-layer confined shear structure which leads to interfacial shear failure. In addition, atomistic static simulation approach is employed to calculate a couple of mineral crystalsâ elastic constants. Furthermore, molecular dynamics simulations are also used to predict the static, thermodynamic, and mechanical properties of three asphalt molecular models.
Fourth, the high performance parallel computing technology is extensively employed throughout this dissertation. In addition to use the large-scale MD program, LAMMPS, the author developed a high performance parallel distributive computing program, MPI_multistress, to implement the multiscale understanding/predicting of materials mechanical behaviors.
Finally, this research also focuses on the evaluation of the susceptibility of aggregates and asphalts to moisture damage through understanding the nano-mechanisms that influence adhesive bond between aggregates and asphalt, as well as the cohesive strength and moisture susceptibility of the specific asphalt-aggregate interfaces. Surface energy theory and pull-out simulation are used to compute the adhesive…
Advisors/Committee Members: Wang, Linbing (committeechair), Puri, Ishwar K. (committee member), Sotelino, Elisa D. (committee member), Filz, George M. (committee member).
Subjects/Keywords: Atomistic Modeling; Asphalt; Interface; Forcefield; Aggregate
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Export
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APA (6th Edition):
Lu, Y. (2010). Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/27540
Chicago Manual of Style (16th Edition):
Lu, Yang. “Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface.” 2010. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/27540.
MLA Handbook (7th Edition):
Lu, Yang. “Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface.” 2010. Web. 17 Jan 2021.
Vancouver:
Lu Y. Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface. [Internet] [Doctoral dissertation]. Virginia Tech; 2010. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/27540.
Council of Science Editors:
Lu Y. Atomistic Characterization and Modeling of the Deformation and Failure Properties of Asphalt-Aggregate Interface. [Doctoral Dissertation]. Virginia Tech; 2010. Available from: http://hdl.handle.net/10919/27540
Virginia Tech
24.
Swenty, Matthew Kenneth.
The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels.
Degree: PhD, Civil Engineering, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/30214
► A set of experimental tests were performed at Virginia Tech to investigate transverse joints and blockouts on full depth concrete bridge deck panels. The joints…
(more)
▼ A set of experimental tests were performed at
Virginia Tech to investigate
transverse joints and blockouts on full depth concrete bridge deck panels. The joints
were designed on a deck replacement project for a rural three span continuous steel girder
bridge in
Virginia. Two cast-in-place and four post-tensioned joints were designed and
tested in cyclical loading. Each joint was tested on a full scale two girder setup in
negative bending with a simulated HS-20 vehicle. The blockouts were built as hollow
concrete rings filled with grout and left to shrink under ambient conditions. Thirteen
combinations of different surface conditions and grouts were designed to test the bond
strength between the materials. The strain profile, cracking patterns, and ponding results
were measured for all specimens. A finite element analysis was performed and calibrated
with the laboratory results.
The cast-in-place joints and the two post-tensioned joints with 1.15 MPa (167 psi)
of initial stress experienced cracking and leaked water by the end of the tests. The two
post-tensioned joints with 2.34 MPa (340 psi) initial stress kept the deck near a tensile
stress of 1.5â (f'c) and performed the best. These transverse joints did not leak water, did
not have full depth cracking, and maintained a nearly linear strain distribution throughout
the design life. Full depth deck panel may be effectively used on continuous bridges if a
sufficient amount of post-tensioning force is applied to the transverse joints. The finite
element model provides a design tool to estimate the post-tensioning force needed to
keep the tensile stresses below the cracking limit.
The blockouts with a roughened surface or an epoxy and a grout equivalent to
Five Star Highway Patch grout had the highest bond stresses, did not leak water, and had
smaller cracks at the grout-concrete interface than the control samples. A minimum bond
strength of 2.5â (f'c) was maintained for all of the specimens with a grout equivalent to
Five Star Highway Patch. A pea gravel additive in the grout reduced shrinkage and
reduced the bond strength. The finite element model provides a design tool to estimate
cracking at the grout-surface interface.
Advisors/Committee Members: Sotelino, Elisa D. (committee member), Wang, Linbing (committee member), Gomez, Jose P. (committee member), Roberts-Wollmann, Carin L. (committeecochair), Cousins, Thomas E. (committeecochair).
Subjects/Keywords: Bridge Deck; Bridge Joints; Post-Tensioning; Grout; Deck Panels
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APA (6th Edition):
Swenty, M. K. (2009). The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/30214
Chicago Manual of Style (16th Edition):
Swenty, Matthew Kenneth. “The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels.” 2009. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/30214.
MLA Handbook (7th Edition):
Swenty, Matthew Kenneth. “The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels.” 2009. Web. 17 Jan 2021.
Vancouver:
Swenty MK. The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels. [Internet] [Doctoral dissertation]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/30214.
Council of Science Editors:
Swenty MK. The Investigation of Transverse Joints and Grouts on Full Depth Concrete Bridge Deck Panels. [Doctoral Dissertation]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/30214
Virginia Tech
25.
Pan, Long.
Effective and Efficient Methodologies for Social Network Analysis.
Degree: PhD, Computer Science, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/25962
► Performing social network analysis (SNA) requires a set of powerful techniques to analyze structural information contained in interactions between social entities. Many SNA technologies and…
(more)
▼ Performing social network analysis (SNA) requires a set of powerful techniques to analyze structural information contained in interactions between social entities. Many SNA technologies and methodologies have been developed and have successfully provided significant insights for small-scale interactions. However, these techniques are not suitable for analyzing large social networks, which are very popular and important in various fields and have special structural properties that cannot be obtained from small networks or their analyses. There are a number of issues that need to be further studied in the design of current SNA techniques. A number of key issues can be embodied in three fundamental and critical challenges: long processing time, large computational resource requirements, and network dynamism.
In order to address these challenges, we discuss an anytime-anywhere methodology based on a parallel/distributed computational framework to effectively and efficiently analyze large and dynamic social networks. In our methodology, large social networks are decomposed into intra-related smaller parts. A coarse-level of network analysis is built based on comprehensively analyzing each part. The partial analysis results are incrementally refined over time. Also, during the analyses process, network dynamic changes are effectively and efficiently adapted based on the obtained results. In order to evaluate and validate our methodology, we implement our methodology for a set of SNA metrics which are significant for SNA applications and cover a wide range of difficulties. Through rigorous theoretical and experimental analyses, we demonstrate that our anytime-anywhere methodology is
Advisors/Committee Members: Santos, Eunice E. (committeechair), Santos, Eugene Jr. (committee member), Sotelino, Elisa D. (committee member), Brown, Ezra A. (committee member), Cao, Yang (committee member).
Subjects/Keywords: Anytime-Anywhere Methodology; Parallel/Distributed Computing; Social Network Analysis
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APA (6th Edition):
Pan, L. (2007). Effective and Efficient Methodologies for Social Network Analysis. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/25962
Chicago Manual of Style (16th Edition):
Pan, Long. “Effective and Efficient Methodologies for Social Network Analysis.” 2007. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/25962.
MLA Handbook (7th Edition):
Pan, Long. “Effective and Efficient Methodologies for Social Network Analysis.” 2007. Web. 17 Jan 2021.
Vancouver:
Pan L. Effective and Efficient Methodologies for Social Network Analysis. [Internet] [Doctoral dissertation]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/25962.
Council of Science Editors:
Pan L. Effective and Efficient Methodologies for Social Network Analysis. [Doctoral Dissertation]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/25962
Virginia Tech
26.
Seek, Michael Walter.
Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method.
Degree: PhD, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/28357
► Z-sections are widely used as secondary members in metal building roof systems. Lateral restraints are required to maintain the stability of a Z-section roof system…
(more)
▼ Z-sections are widely used as secondary members in metal building roof systems. Lateral restraints are required to maintain the stability of a Z-section roof system and provide resistance to the lateral forces generated by the slope of the roof and the effects due to the rotation of the principal axes of the Z-section relative to the plane of the roof sheathing. The behavior of Z-sections in roof systems is complex as they act in conjunction with the roof sheathing as a system and as a light gage cold formed member, is subject to local cross section deformations.
The goal of this research program was to provide a means of predicting lateral restraint forces in Z-section supported roof systems. The research program began with laboratory tests to measure lateral restraint forces in single and multiple span sloped roof systems. A description of the test apparatus and procedure as well as the results of the 40 tests performed is provided in Appendix II.
To better understand the need for lateral restraints and to provide a means of testing different variables of the roof system, two types of finite element models were developed and are discussed in detail in appended Paper I. The first finite element model is simplified model that uses frame stiffness elements to represent the purlin and sheathing. This model has been used extensively by previous researchers and modifications were made to improve correlation with test results. The second model is more rigorous and uses shell finite elements to represent the Z-section and sheathing.
The shell finite element model was used to develop a calculation procedure referred to as the Component Stiffness Method for predicting the lateral restraint forces in Z-section roof systems. The method uses flexural and torsional mechanics to describe the behavior of the Z-section subject to uniform gravity loads. The forces generated by the system of Z-sections are resisted by the "components" of the system: the lateral restraints, the sheathing and Z-section-to-rafter connection. The mechanics of purlin behavior providing the basis for this method are discussed in appended Paper II. The development of the method and the application of the method to supports restraints and interior restraints are provided in appended papers III, IV and V.
Advisors/Committee Members: Murray, Thomas M. (committeechair), Easterling, William Samuel (committee member), Charney, Finley A. (committee member), Setareh, Mehdi (committee member), Sotelino, Elisa D. (committee member).
Subjects/Keywords: diaphragm; standing seam; through-fastened; cold-formed; component stiffness method; finite element method; lateral bracing; Z-section; purlin; metal building
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APA (6th Edition):
Seek, M. W. (2007). Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28357
Chicago Manual of Style (16th Edition):
Seek, Michael Walter. “Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method.” 2007. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/28357.
MLA Handbook (7th Edition):
Seek, Michael Walter. “Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method.” 2007. Web. 17 Jan 2021.
Vancouver:
Seek MW. Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method. [Internet] [Doctoral dissertation]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/28357.
Council of Science Editors:
Seek MW. Prediction of Lateral Restraint Forces in Sloped Z-section Supported Roof Systems Using the Component Stiffness Method. [Doctoral Dissertation]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/28357
Virginia Tech
27.
Pathak, Rakesh.
The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures.
Degree: PhD, Civil Engineering, 2008, Virginia Tech
URL: http://hdl.handle.net/10919/27947
► This dissertation presents work targeted to study the effects of diaphragm flexibility on the seismic performance of light frame wood structures (LFWS). The finite element…
(more)
▼ This dissertation presents work targeted to study the effects of diaphragm flexibility on the seismic performance of light frame wood structures (LFWS). The finite element approach is considered for modeling LFWS as it is more detailed and provides a way to explicitly incorporate individual structural elements and corresponding material properties. It is also suitable for capturing the detailed response of LFWS components and the structure as a whole. The finite element modeling methodology developed herein is in general based on the work done by the other finite element researchers in this area. However, no submodeling or substructuring of subassemblages is performed and instead a detailed model considering almost every connection in the shear walls and diaphragms is developed. The studs, plates, sills, blockings and joists are modeled using linear isotropic three dimensional frame elements. A linear orthotropic shell element incorporating both membrane and plate behavior is used for the sheathings. The connections are modeled using oriented springs with modified Stewart hysteresis spring stiffnesses. The oriented spring pair has been found to give a more accurate representation of the sheathing to framing connections in shear walls and diaphragms when compared to non-oriented or single springs typically used by most researchers in the past. Fifty six finite element models of LFWS are created using the developed methodology and eighty eight nonlinear response history analyses are performed using the Imperial Valley and Northridge ground motions. These eighty eight analyses encompass the parametric study on the house models with varying aspect ratios, diaphragm flexibility and lateral force resisting system. Torsionally irregular house models showed the largest range of variation in peak base shear of individual shear walls, when corresponding flexible and rigid diaphragm models are compared. It is also found that presence of an interior shear wall helps in reducing peak base shears in the boundary walls of torsionally irregular models. The interior walls presence was also found to reduce the flexibility of diaphragm. A few analyses also showed that the nail connections are the major source of in-plane flexibility compared to sheathings within a diaphragm, irrespective of the aspect ratio of the diaphragm.
A major part of the dissertation focuses on the development of a new high performance nonlinear dynamic finite element analysis program which is also used to analyze all the LFWS finite element models presented in this study. The program is named WoodFrameSolver and is written on a mixed language platform Microsoft Visual Studio .NET using object-oriented C++, C and FORTRAN. This tool set is capable of performing basic structural analysis chores like static and dynamic analysis of 3D structures. It has a wide collection of linear, nonlinear and hysteretic elements commonly used in LFWS analysis. The advanced analysis features include static, nonlinear dynamic and incremental dynamic analysis. A unique aspect of…
Advisors/Committee Members: Charney, Finley A. (committeechair), Easterling, William Samuel (committee member), Plaut, Raymond H. (committee member), Sotelino, Elisa D. (committee member), Hindman, Daniel P. (committee member).
Subjects/Keywords: Finite Element; Light Frame Wood Structure; Nonlinear Dynamic Analysis; Static; Object Oriented C++; Diaphragm Flexibility
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APA (6th Edition):
Pathak, R. (2008). The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/27947
Chicago Manual of Style (16th Edition):
Pathak, Rakesh. “The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures.” 2008. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/27947.
MLA Handbook (7th Edition):
Pathak, Rakesh. “The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures.” 2008. Web. 17 Jan 2021.
Vancouver:
Pathak R. The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures. [Internet] [Doctoral dissertation]. Virginia Tech; 2008. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/27947.
Council of Science Editors:
Pathak R. The Effects of Diaphragm Flexibility on the Seismic Performance of Light Frame Wood Structures. [Doctoral Dissertation]. Virginia Tech; 2008. Available from: http://hdl.handle.net/10919/27947
Virginia Tech
28.
Wang, Yongping.
Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images.
Degree: PhD, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/28748
► Simulative tests, such as asphalt pavement analyzer (APA), Hamberg rut tester etc. have been widely used to evaluate the performance of asphalt mixtures. However, simulative…
(more)
▼ Simulative tests, such as asphalt pavement analyzer (APA), Hamberg rut tester etc. have been widely used to evaluate the performance of asphalt mixtures. However, simulative tests to evaluate the performance of the mixtures cannot give fundamental properties of Asphalt Concrete (AC) due to the complex stress and strain fields. On the other hand, due to the availability of high-performance computing systems and software, numerical techniques are gaining popularity. This dissertation presents a computational simulation method of the APA tests in order to evaluate the rutting potential of asphalt mixtures based on actual microstructure reconstructed from X-ray tomography images. In the study, the microstructure of AC is obtained through the analysis of X-ray images, which included the digital information of the microstructure for the scanned specimen. In the simulations the three phases, mastic (asphalt binder with mineral filler), aggregates, and voids are assigned with different material properties. Aggregates are modeled as an elastic material, and air voids are removed during the loading steps. The adopted two-layer model is only used to represent the rate and temperature dependent behavior of the mastics.
The parameters are obtained with inverse methods. Based on the sensitivity analysis of the parameters, an iterative procedure is performed to optimize the parameters using the experimental measurement and results of the model simulations. A parametric study is also conducted to study the effect of major parameters such as the stiffness ratio of the networks on the macro response of the model. The simulation results obtained shows a good agreement with the experimental results.
The dissertation also presents a method to measure micro strains in asphalt mixture. An automated procedure using tomography images to reconstruct three-dimensional particles is developed. The translations of the particles are obtained from the coordinate differences of particles' mass centers before and after the APA testing. The micro and macro strains in the mixture are calculated based on the particle translations. A good correlation is found between measured strains and experimental result.
Advisors/Committee Members: Wang, Linbing (committeechair), Sotelino, Elisa D. (committee member), Flintsch, Gerardo W. (committee member), Trani, Antoino A. (committee member), Dove, Joseph E. (committee member).
Subjects/Keywords: Viscoplasticity; Permanent Deformation; Asphalt Pavement Analyzer; Tomography Imaging
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APA ·
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APA (6th Edition):
Wang, Y. (2007). Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28748
Chicago Manual of Style (16th Edition):
Wang, Yongping. “Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images.” 2007. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/28748.
MLA Handbook (7th Edition):
Wang, Yongping. “Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images.” 2007. Web. 17 Jan 2021.
Vancouver:
Wang Y. Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images. [Internet] [Doctoral dissertation]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/28748.
Council of Science Editors:
Wang Y. Digital Simulative Test of Asphalt Mixtures Using Finite Element Method and X-Ray Tomography Images. [Doctoral Dissertation]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/28748
Virginia Tech
29.
Phillips, Rhonda D.
A Probabilistic Classification Algorithm With Soft Classification Output.
Degree: PhD, Computer Science, 2009, Virginia Tech
URL: http://hdl.handle.net/10919/26701
► This thesis presents a shared memory parallel version of the hybrid classification algorithm IGSCR (iterative guided spectral class rejection), a novel data reduction technique that…
(more)
▼ This thesis presents a shared memory parallel version of the hybrid classification algorithm IGSCR (iterative guided spectral class rejection), a novel data reduction technique that can be used in conjunction with PIGSCR (parallel IGSCR), a noise removal method based on the maximum noise fraction (MNF), and a continuous version of IGSCR (CIGSCR) that outputs soft classifications. All of the above are either classification algorithms or preprocessing algorithms necessary prior to the classification of high dimensional, noisy images. PIGSCR was developed to produce fast and portable code using Fortran 95, OpenMP, and the Hierarchical Data Format version 5 (HDF5) and accompanying data access library. The feature reduction method introduced in this thesis is based on the singular value decomposition (SVD). This feature reduction technique demonstrated that SVD-based feature reduction can lead to more accurate IGSCR classifications than PCA-based feature reduction.
This thesis describes a new algorithm used to adaptively filter a remote sensing dataset based on signal-to-noise ratios (SNRs) once the maximum noise fraction (MNF) has been applied.
The adaptive filtering scheme improves image quality as shown by estimated SNRs and classification accuracy improvements greater than 10%. The continuous iterative guided spectral class rejection (CIGSCR) classification method is based on the iterative guided spectral class rejection (IGSCR) classification method for remotely sensed data. Both CIGSCR and IGSCR use semisupervised clustering to locate clusters that are associated with classes in a classification scheme. This type of semisupervised classification method is particularly useful in remote sensing where datasets are large, training data are difficult to acquire, and clustering makes the identification of subclasses adequate for training purposes less difficult. Experimental results indicate that the soft classification output by CIGSCR is reasonably accurate (when compared to IGSCR), and the fundamental algorithmic changes in CIGSCR (from IGSCR) result in CIGSCR being less sensitive to input parameters that influence iterations.
Advisors/Committee Members: Watson, Layne T. (committeechair), Wynne, Randolph H. (committee member), Sotelino, Elisa D. (committee member), Sandu, Adrian (committee member), Ribbens, Calvin J. (committee member), Cao, Yang (committee member).
Subjects/Keywords: classification; data reduction; parallel processing; remote sensing; high performance computing; cluster evaluation
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APA ·
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Export
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APA (6th Edition):
Phillips, R. D. (2009). A Probabilistic Classification Algorithm With Soft Classification Output. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/26701
Chicago Manual of Style (16th Edition):
Phillips, Rhonda D. “A Probabilistic Classification Algorithm With Soft Classification Output.” 2009. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/26701.
MLA Handbook (7th Edition):
Phillips, Rhonda D. “A Probabilistic Classification Algorithm With Soft Classification Output.” 2009. Web. 17 Jan 2021.
Vancouver:
Phillips RD. A Probabilistic Classification Algorithm With Soft Classification Output. [Internet] [Doctoral dissertation]. Virginia Tech; 2009. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/26701.
Council of Science Editors:
Phillips RD. A Probabilistic Classification Algorithm With Soft Classification Output. [Doctoral Dissertation]. Virginia Tech; 2009. Available from: http://hdl.handle.net/10919/26701
Virginia Tech
30.
Liu, Zihong.
Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck.
Degree: PhD, Civil Engineering, 2007, Virginia Tech
URL: http://hdl.handle.net/10919/28234
► A fiber reinforced polymer (FRP) composite cellular deck system was used to rehabilitate a historical cast iron thru-truss structure (Hawthorne St. Bridge in Covington, Virginia).…
(more)
▼ A fiber reinforced polymer (FRP) composite cellular deck system was used to rehabilitate a historical cast iron thru-truss structure (Hawthorne St. Bridge in Covington,
Virginia). This research seeks to address following technical needs and questions to advance FRP deck application.
The critical panel-to-panel connections were developed and evolved through a four-stage study and finally realized using full width, adhesively bonded tongue and groove splices with scarfed edges. Extensive experimental study under service, strength and fatigue loads in a full-scale two-bay mock-up test and a field test was performed. Test results showed that no crack initiated in the joints under service load and no significant change in stiffness or strength of the joint occurred after 3,000,000 cycles of fatigue loading. Various issues related to constructability of FRP deck systems were investigated and construction guidelines and installation procedures for the deck system were established.
The structural performance of the FRP-on-steel-superstructure system was examined in the laboratory and field under service load. Tests results confirmed the following findings: (1) the clip-type of panel-to-stringer connection provides little composite action as expected, which fulfilled the design intention; (2) local effects play an important role in the performance of FRP deck; (3) the FRP deck design is stiffness driven rather than strength driven like traditional concrete deck.
Finally, an FEM parametric study was conducted to examine two important design issues concerning the FRP decks, namely deck relative deflection and LDF of supporting steel girders. Results from both FEM and experiments show that the strip method specified in AASHTO LRFD specification (AASHTO 2004) as an approximate method of analysis can also be applied to unconventional FRP decks as a practical method. However, different strip width equations have to be determined by either FEM or experimental methods for different types of FRP decks. In this study, one such an equation has been derived for the Strongwell deck. In addition, the AASHTO LDF equations for glued laminated timber decks on steel stringers provide good estimations of LDFs for FRP-deck-on-steel-girder bridges. The lever rule can be used as an appropriately conservative design method to predict the LDFs of FRP-deck-on-steel-girder bridges.
Advisors/Committee Members: Cousins, Thomas E. (committeechair), Roberts-Wollmann, Carin L. (committee member), Plaut, Raymond H. (committee member), Sotelino, Elisa D. (committee member), Lesko, John J. (committeecochair).
Subjects/Keywords: finite element; rehabilitation; bridge deck; structure; pultrusion; Fiber-reinforced polymer (FRP); composite
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APA ·
Chicago ·
MLA ·
Vancouver ·
CSE |
Export
to Zotero / EndNote / Reference
Manager
APA (6th Edition):
Liu, Z. (2007). Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck. (Doctoral Dissertation). Virginia Tech. Retrieved from http://hdl.handle.net/10919/28234
Chicago Manual of Style (16th Edition):
Liu, Zihong. “Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck.” 2007. Doctoral Dissertation, Virginia Tech. Accessed January 17, 2021.
http://hdl.handle.net/10919/28234.
MLA Handbook (7th Edition):
Liu, Zihong. “Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck.” 2007. Web. 17 Jan 2021.
Vancouver:
Liu Z. Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck. [Internet] [Doctoral dissertation]. Virginia Tech; 2007. [cited 2021 Jan 17].
Available from: http://hdl.handle.net/10919/28234.
Council of Science Editors:
Liu Z. Testing and Analysis of a Fiber-Reinforced Polymer (FRP) Bridge Deck. [Doctoral Dissertation]. Virginia Tech; 2007. Available from: http://hdl.handle.net/10919/28234
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Open Access Theses and Dissertations