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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

A partial differential equation to model the Tacoma Narrows Bridge failure

Swatzel, James Paul 01 January 2004 (has links)
The purpose of this thesis was to examine a partial differential equation to model the Tacoma Narrows bridge failure. This thesis will examine the equation developed by Lazer and McKenna to model a suspension bridge in no wind.
62

Superstructure Bridge Selection Based on Bridge Life-Cycle Cost Analysis

Stefan Leonardo Leiva Maldonado (6853484) 14 August 2019 (has links)
<div>Life cycle cost analysis (LCCA) has been defined as a method to assess the total cost of a project. It is a simple tool to use when a single project has different alternatives that fulfill the original requirements. Different alternatives could differ in initial investment, operational and maintenance costs among other long term costs. The cost involved in building a bridge depends upon many different factors. Moreover, long-term cost needs to be considered to estimate the true overall cost of the project and determine its life-cycle cost. Without watchful consideration of the long-term costs and full life cycle costing, current investment decisions that look attractive could result in a waste of economic resources in the future. This research is focused on short and medium span bridges (between 30-ft and 130-ft) which represents 65\% of the NBI INDIANA bridge inventory. </div><div><br></div><div>Bridges are categorized in three different groups of span ranges. Different superstructure types are considered for both concrete and steel options. Types considered include: bulb tees, AASHTO prestressed beams, slab bridges, prestressed concrete box beams, steel beams, steel girders, folded plate girders and simply supported steel beams for dead load and continuous for live load (SDCL). A design plan composed of simply supported bridges and continuous spans arrangements was carried out. Analysis for short and medium span bridges in Indiana based on LCCA is presented for different span ranges and span configurations. </div><div><br></div><div>Deterministic and stochastic analysis were done for all the span ranges considered. Monte Carlo Simulations (MCS) were used and the categorization of the different superstructure alternatives was done based on stochastic dominance. First, second, almost first and almost second stochastic dominance rules were used to determined the efficient set for each span length and all span configurations. Cost-effective life cycle cost profiles for each superstructure type were proposed. Additionally, the top three cost-effective alternatives for superstructure types depending on the span length are presented as well as the optimum superstructure types set for both simply supported and continuous beams. Results will help designers to consider the most cost-effective bridge solution for new projects, resulting in cost savings for agencies involved.</div>
63

Flyover and urbanism: colonizing highways.

January 2003 (has links)
Lau Tin Hang, Peter. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2002-2003, design report." / Chapter I. --- Introduction --- p.p.1 / Chapter II. --- Research - Flyover and Urbanism --- p.p.2 / Chapter i. --- Typology Definition --- p.p.3 / Chapter ´Ø --- Type 1 - Living with Flyover --- p.p.4-5 / Chapter ´Ø --- Type 2 - Flyover and Open Space --- p.p.6-7 / Chapter ´Ø --- Type 3 - Flyover as Transition --- p.p.8-9 / Chapter ´Ø --- Type 4 - Flyover as Generator --- p.p.10-11 / Chapter ´Ø --- Type 5 - Flyover and Water --- p.p.12-13 / Chapter ´Ø --- Type 6 - Flyover as Place --- p.p.14-15 / Chapter ii. --- Research Main Body --- p.p.16 / Introduction --- p.P.17 / Pedestrians' Perspective --- p.p.18 / Chapter ´Ø --- Overview --- p.p.19-22 / Chapter ´Ø --- Open Spaces under Flyovers --- p.p.23-26 / Chapter ´Ø --- Structures under Flyovers --- p.p.27-30 / Residents' Perspective --- p.p.31 / Chapter ´Ø --- Impact of flyovers to residents --- p.p.32-33 / Chapter ´Ø --- Building type within city grid --- p.p.34 / Chapter ´Ø --- New housing design in response to Flyovers --- p.p.35 / Drivers' Perspective --- p.p.36 / Chapter ´Ø --- View on Flyovers --- p.p.37-46 / Chapter ´Ø --- Spatial Experience --- p.p.47-48 / Chapter ´Ø --- Visual Experience --- p.p.49-50 / Chapter iii. --- Precedent Study --- p.p.51-58 / Chapter III. --- Design - Colonizing Highways --- p.p.59 / Chapter i. --- Design Statement --- p.p.60 / Chapter ii. --- Issues of Roundabouts in Hong Kong --- p.p.61-62 / Chapter iii. --- Site Analysis --- p.p.63-67 / Chapter iv. --- Design / Chapter ´Ø --- A New Order - Massing Study --- p.p.68-70 / Chapter ´Ø --- Sectional Organization --- p.p.71-73 / Chapter ´Ø --- Planning Organization --- p.p.74-75 / Chapter ´Ø --- Residential Units --- p.p.76-77 / Chapter ´Ø --- Facade Design --- p.p.78 / Chapter ´Ø --- Ground Plane Design --- p.p.79-81 / Chapter v. --- Appendix / Chapter ´Ø --- Section A-A' --- p.p.82 / Chapter ´Ø --- Section B-B' --- p.p.83 / Chapter ´Ø --- Section C-C' --- p.p.84 / Chapter ´Ø --- Elevation --- p.p.85-87 / Chapter ´Ø --- Balcony detail --- p.p.88 / Chapter ´Ø --- Kitchen wall and floor detail --- p.p.89
64

Flyover and urbanism: reweaving the new & old urban fabrics.

January 2003 (has links)
Wong Yeuk Hay. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2002-2003, design report." / Chapter I. --- Introduction --- p.p.1 / Chapter II. --- Research - Flyover and Urbanism --- p.p.2 / Chapter i. --- Typology Definition --- p.p.3 / Chapter ´Ø --- Type 1 - Living with Flyover --- p.p.4-5 / Chapter ´Ø --- Type 2 - Flyover and Open Space --- p.p.6-7 / Chapter ´Ø --- Type 3 - Flyover as Transition --- p.p.8-9 / Chapter ´Ø --- Type 4 - Flyover as Generator --- p.p.10-11 / Chapter ´Ø --- Type 5 - Flyover and Water --- p.p.12-13 / Chapter ´Ø --- Type 6 - Flyover as Place --- p.p.14-15 / Chapter ii. --- Research Main Body --- p.p.16 / Introduction --- p.p.17 / Pedestrians' Perspective --- p.p.18 / Chapter ´Ø --- Overview --- p.p.19-22 / Chapter ´Ø --- Open Spaces under Flyovers --- p.p.23-26 / Chapter ´Ø --- Structures under Flyovers --- p.p.27-30 / Residents' Perspective --- p.p.31 / Chapter ´Ø --- Impact of flyovers to residents --- p.p.32-33 / Chapter ´Ø --- Building type within city grid --- p.p.34 / Chapter ´Ø --- New housing design in response to Flyovers --- p.p.35 / Drivers' Perspective --- p.p.36 / Chapter ´Ø --- View on Flyovers --- p.p.37-46 / Chapter ´Ø --- Spatial Experience --- p.p.47-48 / Chapter ´Ø --- Visual Experience --- p.p.49-50 / Chapter iii. --- Precedent Study --- p.p.51-58 / Chapter III. --- Design - Reweaving the New & Old Urban Fabrics --- p.p.59 / Chapter i. --- Introduction --- p.p.60 / Chapter ii. --- Site Analysis --- p.p.61-65 / Chapter iii. --- Urban Design Strategies --- p.p.66-67 / Chapter iv. --- Final Design - Civic Bridge / Chapter ´Ø --- Conceptual diagrams --- p.p.68-69 / Chapter ´Ø --- Plans --- p.p.70-72 / Chapter ´Ø --- Elevations and Sections --- p.p.73-75 / Chapter ´Ø --- Perspective --- p.p.76-77 / Chapter ´Ø --- Photos --- p.p.78-79
65

HKSZ bridgescape: towards a post-border era. / Hong Kong Shenzhen bridgescape: towards a post-border era

January 2010 (has links)
Law Pui Yin, Kathy. / "Architecture Department, Chinese University of Hong Kong, Master of Architecture Programme 2009-2010, design report." / "May 2010." / Includes bibliographical references (p. [102]-103). / 01 / BACKGROUND / Introduction / Case Study - Political Borders / HKSZ Border Future Speculation (Timeline Study) / Criticisms on HK Government / ISSUE / Interface / Urban Polarity / PROGRAM / Program Research / Program Proposal (Whole Border) / 02 / SITE / Site Selection / Site Planning / 03 / DESIGN CONCEPT / Case Study - Habitable Bridge / Case Study - River as a Physical Border / Design Concept / the DESIGN / Situated At Site / Program / Terraces / Types of Space / Types of Space: Truss BoxPartition / 04 / REFERENCE
66

Behaviour of open web precast bridge girders : experimental study

Córdoba G., Roque A. January 1974 (has links)
No description available.
67

A Contact Element Approach with Hysteresis Damping for the Analysis and Design of Pounding in Bridges

Muthukumar, Susendar 26 November 2003 (has links)
Earthquake ground motion can induce out-of-phase vibrations between adjacent structures due to differences in dynamic characteristics, which can result in impact or pounding of the structures if the at-rest separation is insufficient to accommodate the relative displacements. In bridges, seismic pounding between adjacent decks or between deck and abutment can result in localized deck damage, bearing failure, damage to shear keys and abutments, and even contribute to the collapse of bridge spans. This study investigates pounding in bridges from an analytical perspective. A simplified nonlinear model of a multiple-frame bridge is developed in MATLAB incorporating the effects of inelastic frame action, nonlinear hinge behavior and abutments. The equations of motion of the bridge response to longitudinal ground excitation are assembled and solved using the fourth-order Runge-Kutta method. Pounding is simulated using contact force-based models such as the linear spring, Kelvin and Hertz models, as well as the momentum-based stereomechanical method. In addition, a Hertz contact model with nonlinear damping (Hertzdamp model) is also introduced to model impact. The primary factors controlling the pounding response are identified as the frame period ratio, ground motion effective period ratio, restrainer stiffness ratio and frame ductility ratio. Pounding is most critical for highly out-of-phase frames. Impact models without energy dissipation overestimate the stiff system displacements by 15%-25% for highly out-of-phase, elastic systems experiencing moderate to strong ground excitation. The Hertzdamp model is found to be the most effective in representing impact. Traditional column hysteresis models such as the elasto-plastic and bilinear models underestimate the stiff system amplification and overestimate the flexible system amplification due to impact, when compared with stiffness and strength degrading models. Strength degradation and pounding are critical on the stiff system response to near field ground motions, for highly out-of-phase systems. Current design procedures are adequate in capturing the nonlinear hinge response when the bridge columns are elastic, but require revisions such as the introduction of time dependent reduction factors, and a frame design period to work for inelastic situations. Finally, a bilinear truss element with a gap is proposed for implementing energy dissipating impact models in commercial structural software.
68

Effects of thermal loads on Texas steel bridges

Chen, Quan, 1977- 07 September 2012 (has links)
The effects of thermal loads on steel bridges are not well understood. Although thermal effects are discussed in the AASHTO specifications, the appropriateness of the recommended thermal gradients is questionable. Thermal effects on the bridges can impact the design of the steel superstructure, the support bearings, and even the bridge piers. Previous field monitoring of steel trapezoidal box girder bridges has shown that thermal stresses on the order of ±5 ksi were not uncommon under regular daily thermal cycles. Stresses induced during annual thermal cycles may be potentially larger than those during daily thermal cycles. Recent data has shown that the bearings that are to allow the girders to expand and contract freely due to thermal movements are not frictionless. Because of the bearing friction, the supporting piers must flex to accommodate the bridge movements. In curved girder applications, questions have been raised by designers and contractors regarding the proper orientation of guided bearings. This research study includes field measurements, laboratory tests and finite element parametric analyses. The bearings of nine bridges in the Houston area have been instrumented and monitored for more than a year to measure bearing movements due to changes in temperature. Instrumentation of the steel girders on one of the Houston bridges was made utilizing thermocouples and vibrating wire strain gages to measure temperature distribution and thermal stresses. In addition, strain gages and thermal couples were applied to the steel girders and concrete bridge deck on a simple twin box girder bridge located at the Ferguson Structural Engineering Laboratory in Austin, Texas. The data from the field monitoring and laboratory tests were used to validate a finite element model. Based on this model, a detailed parametric study was conducted to investigate the effects of bridge configuration. It is found that under the given weather conditions, the most critical thermal loads are achieved under the following bridge configurations: N-S bridge orientation, shorter lengths of the concrete deck overhang, deeper steel girder webs, thinner concrete decks, and larger spacing between two box girders. To evaluate the effect of environmental conditions and obtain extreme thermal loads for design purposes, the most critical configuration of bridge sections was modeled for thermal analysis with Texas weather data from 1961 to 2005 as the input environmental conditions. Four cities were considered to bound Texas weather conditions. Based on the thermal analyses, a 45-year sample data of thermal parameters were used to describe the temperature field over a section. Extreme value analyses of the sample data were performed to obtain the relationship between thermal loads and return periods. The thermal loads with 100-year return period were compared to the ones suggested by AASHTO. The thermal loads with 100-year return period were used to investigate structural response. The effect of bearing orientation and the point of fixity were studied. A rigid body model was proposed to estimate thermal movements at the ends, which matched those obtained from field monitoring and finite element analysis. The maximum possible thermal stresses were also evaluated. Design suggestions are put forward based on the analysis. / text
69

Behaviour of open web precast bridge girders : experimental study

Córdoba G., Roque A. January 1974 (has links)
No description available.
70

Next generation seismic fragility curves for california bridges incorporating the evolution in seismic design philosophy

Ramanathan, Karthik Narayan 02 July 2012 (has links)
Quantitative and qualitative assessment of the seismic risk to highway bridges is crucial in pre-earthquake planning, and post-earthquake response of transportation systems. Such assessments provide valuable knowledge about a number of principal effects of earthquakes such as traffic disruption of the overall highway system, impact on the regions' economy and post-earthquake response and recovery, and more recently serve as measures to quantify resilience. Unlike previous work, this study captures unique bridge design attributes specific to California bridge classes along with their evolution over three significant design eras, separated by the historic 1971 San Fernando and 1989 Loma Prieta earthquakes (these events affected changes in bridge seismic design philosophy). This research developed next-generation fragility curves for four multispan concrete bridge classes by synthesizing new knowledge and emerging modeling capabilities, and by closely coordinating new and ongoing national research initiatives with expertise from bridge designers. A multi-phase framework was developed for generating fragility curves, which provides decision makers with essential tools for emergency response, design, planning, policy support, and maximizing investments in bridge retrofit. This framework encompasses generational changes in bridge design and construction details. Parameterized high-fidelity three-dimensional nonlinear analytical models are developed for the portfolios of bridge classes within different design eras. These models incorporate a wide range of geometric and material uncertainties, and their responses are characterized under seismic loadings. Fragility curves were then developed considering the vulnerability of multiple components and thereby help to quantify the performance of highway bridge networks and to study the impact of seismic design principles on the performance within a bridge class. This not only leads to the development of fragility relations that are unique and better suited for bridges in California, but also leads to the creation of better bridge classes and sub-bins that have more consistent performance characteristics than those currently provided by the National Bridge Inventory. Another important feature of this research is associated with the development of damage state definitions and grouping of bridge components in a way that they have similar consequences in terms of repair and traffic implications following a seismic event. These definitions are in alignment with the California Department of Transportation's design and operational experience, thereby enabling better performance assessment, emergency response, and management in the aftermath of a seismic event. The fragility curves developed as a part of this research will be employed in ShakeCast, a web-based post-earthquake situational awareness application that automatically retrieves earthquake shaking data and generates potential damage assessment notifications for emergency managers and responders. / Errata added at request of advisor and approved by Graduate Office, March 15 2016.

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