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Chestnutt, Brian James. "Design aspects of multicable suspension bridges." Thesis, Queen's University Belfast, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.317107.
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Harbi, Hani. "Stability of certain models of suspension bridges." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 2001. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/NQ58283.pdf.
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Diogo, Honório José. "Conceptual design of long-span cantilever constructed concrete bridges." Thesis, KTH, Bro- och stålbyggnad, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36994.
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Takács, Peter F. "Deformations in Concrete Cantilever Bridges : Observations and Theoretical Modelling." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Engineering Science and Technology, 2002. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-112.
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The thesis deals with the deformation problem of segmental, cast-in-place concrete cantilever bridges. This type of bridge has shown some propensity to develop larger deflections than those were predicted in the design calculation. Excessive deflections may lead to deterioration of aesthetics, serviceability problems and eventually early reconstruction of the bridge. Also in the construction stages the deflections have to be properly compensated to achieve the smooth camber in the completed bridge deck.
Deformation prediction in concrete cantilever bridges is not as reliable as it would be necessary due to several factors. The high degree of uncertainty in creep and shrinkage prediction in concrete constitutes the major difficulty. Other factors are the complex segmental construction procedure and the sensitivity of the deformations to variations in the construction schedule, the uncertainty in estimating the frictional loss of prestress and relaxation in the prestressing tendons and uncertainty in estimating model parameters such as temperature and relative humidity.
The doctoral study was initiated with the objective to improve deformation prediction in segmentally cast concrete cantilever bridges and to establish guidelines for deformation analysis based on advanced numerical methods.
A database on observed deformations in three modern long span concrete cantilever bridges in Norway has been established. Two of the bridges were partly constructed from lightweight aggregate concrete. The deformations have been monitored since the construction stages up to the present time. The measurements cover the construction stages and the service life of 14, 8 and 3 years, respectively for the three bridges. The measured deformations are deflections in the superstructure and in one of the bridges, also strain measurements in the piers and the superstructure.
A sophisticated numerical model was created for deformation analysis. The numerical model realistically simulates the segmental construction procedure and the entire life span of the bridge. The effects of the segmental construction method, temporarily supports and constraints and changes in the structure system during construction are taken into account. The model considers the different concrete age from segment to segment, the sequential application of permanent loads and prestressing and the effect of temporary loads. The prestressing tendons are individually modelled with their true profile taking into account the variation of the effective prestressing force along the length of the tendon and with time.
The finite element model consists of beam elements which are based on an advanced beam element formulation. The beam model was verified against a robust two-and-a-half dimensional shell model concerning its general performance and some specific issues. The comparison confirmed the accuracy of the beam model. Existing experimental data on creep and shrinkage in lightweight aggregate concrete and high strength concrete were evaluated in comparison with theoretical models. The main focus was on the CEB-FIP Model Code 1990 and its subsequent extensions. The findings were considered in the numerical studies.
Deformations of the three bridges were computed. The CEB-FIP Model Code 1990 material model was used for concrete for the most part. The elastic moduli were taken from test results where they were available. The creep coefficient and the shrinkage strain of the lightweight aggregate concrete were assumed equal to those of normal density concrete of the same strength. The agreement between the calculated and the measured deformations were satisfactory in view of the large uncertainty involved in theoretical prediction. While moderate differences were observed in most cases, no clear overall tendency toward underor overestimation was found. In subsequent numerical studies, the sensitivity of the deformations to variations in various model parameters was investigated. The B3 model was compared to the CEB-FIP Model Code 1990 in the analysis of one of the bridges, where the latter model showed somewhat better agreement with the measurements.
The last part of the work concerned a robust probabilistic analysis which was based on a Monte Carlo simulation. The objective of the probabilistic analysis was to estimate the statistical properties of the deformation responses. With the distribution function of a given deformation response being known, the confidence limit for the deformation can be determined. It is recommended to design the bridge for the long-time deflection which represents a certain confidence limit (e.g. the 95 % confidence limit) of the response rather than its mean. Such way the risk that the bridge will suffer intolerable deflection over its life span can be minimised.
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Harbi, Hani. "Dynamic models of suspension bridges and their stabilities." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/mq20920.pdf.
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Chacar, Jean-Pierre Michel 1979. "Design of cable systems for cable suspension bridges." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84254.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001."June 2001."
Includes bibliographical references (leaves 37-38).
by Jean-Pierre Michel Chacar.
M.Eng.
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Nowera, M. H. A. H. "A study of two-span prestressed concrete suspension bridges." Thesis, University of Southampton, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.375740.
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Shi, Miao M. Eng Massachusetts Institute of Technology. "Energy harvesting from wind-induced vibration of suspension bridges." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/82825.
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Thesis (M. Eng.)--Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2013.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 73-75).
Recently, an extensive amount of research has been focused on energy harvesting from structural vibration sources for wireless self-powered microsystem applications. One method of energy harvesting is using electromagnetic mechanism to transfer mechanical energy into electrical energy. This has been studied in depth at the micro-level scale. In this thesis, using the same methodology that was developed for the micro-level scale, this technique is expanded for larger scale applications. A linear resonant device of the size 40mm in diameter, weight of 2 kg is proposed to be installed on a suspension bridge deck to harvest energy and to control the motion of the bridge deck. The feasibility of the installation of the device is studied with respect to the amount of energy that could be harvested. The commercial software SAP2000 was used to carry out the analysis of the structural response of the suspension bridge to wind loading. Furthermore, the potential amount of energy that can be harvested is calculated. Keywords: Electromagnetic Energy Harvesting; Suspension bridge; Low frequency energy harvesting; Vibration control;
by Miao Shi.
M.Eng.
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Papatheodorou, Marianthi. "Dynamic finite element modelling, measurement and updating of cable stayed bridges." Thesis, University of Bristol, 2001. http://hdl.handle.net/1983/9bc30f08-7040-4ade-be27-8a56eacc1826.
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Bakis, Konstantinos Nikolaos. "Active and passive aeroelastic control of long-span suspension bridges." Thesis, University of Oxford, 2016. https://ora.ox.ac.uk/objects/uuid:d076b9f0-d110-4816-a0b9-4e8c67a4edfb.
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Long-span bridges constitute landmark projects, whose iconic impact blends together aesthetic creativity and structural competence. The simplicity of their form is contrasted by the magnitude of their scale, and the span length, in particular, relates to the structure's technical efficiency as well as to its visual impression. Simple extrapolation of rather conventional concepts, however, does not usually lead to great progress in technological development and this might prove to be the case for the aeroelastic performance of such structures as the trend to increase their slenderness continues. The aim of this work is to establish a framework for implementing control devices, primarily in the form of aerodynamic appendices, for suppressing aeroelastic instabilities and mitigating wind induced vibrations in long-span bridges. First, a simplified, sectional structural bridge model is created, and its interaction with a constant velocity airstream is analysed using thin-aerofoil theory. Two different passive control strategies are then considered, separately and in combination. The first makes use of trailing and leading-edge flaps adjacent to the bridge deck. The rotating motion of the flaps is triggered by the deck's movement through a combination of connecting springs, dampers and the newly introduced inerter device. The second approach combines the aerodynamic stabilizing effect of the flaps with a driving force provided by a suspended mass, placed inside the box girder. For both strategies, special attention is given to ensuring that the proposed passive control system attains optimum robustness margins, that is, maximum tolerance to the uncertainties which accompany any physical system. The analysis is then generalized by extending it to a discretized bridge aeroelastic model, which considers full multimodal interaction. The structural component of the modelling makes use of a reduced-size finite element formulation, in which the contribution of both the girder and the main cables is combined into single structural elements, thus reducing computation effort. The introduction of aerodynamic forces follows both thin-aerofoil theory and the flutter derivatives approach and the fluid-structure interaction is cast in a state space form in the Laplace domain. This framework is particularly convenient for control analysis and design. Two control approaches are considered: an active approach, which demands an external power source and digital control system, and a purely passive mechanical network approach, building on the earlier sectional investigation. The passive control configuration proposed has the advantages of: simultaneously increasing flutter and torsional divergence limits, being easily implementable while avoiding the use of external linkages and finally dispensing the need to be anchored to a ground reference point. Implementation of the proposed feedback mechanism to the bridge aeroelastic model proves its effectiveness during the early construction stages of a suspension bridge as well as in its completed stage.
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Soli, Riccardo. "Non-Linear Analysis and Design of Cable Systems in Suspension Bridges." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018. http://amslaurea.unibo.it/15045/.
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The scope of the presented research project is to provide a reliable guideline for the preliminary design of cable supported bridges. In order to pursue this objective, a thorough literature research has been conducted in the first phase of the project. This has been of relevant importance for the understanding of the subject and further implementation of the case study: the design of a suspension bridge model in Strand7.
The conducted research has shown that there is not a unique book to which engineers may refer in order to conduct the type of analysis presented in this project. Therefore, the proposed guideline has been created on the basis of multiple text books.
Further analyses have been conducted in order to evaluate the accuracy of theoretical-based results and software-based results. In particular the Steinman Modified Elastic Treatment has been applied to the case study and its results compared to those obtained on Strand7. The obtained results finally show that Steinman’s Theory represents a quick and reliable method to be adopted for preliminary design purposes as its results are in line with Strand7 results.
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Akbar, Sidra, and Mathias Carlie. "Long-term deformation of balanced cantilever bridges due to non-uniform creep and shrinkage." Thesis, KTH, Betongbyggnad, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-300449.
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Balanced cantilever bridges have historically experienced excessive deformations. Previous researchsuggeststhat the cause may be due to differential thickness in the box girder cross-section and underestimation of creep and shrinkage.In this project, the long-term deformationof balanced cantilever bridges due tonon-uniformcreep and shrinkage have been investigated. The non-uniformcreep and shrinkage arecaused by variations in drying rates for the different parts of the box-girder cross-sections.A finite element model was createdintheprogram Abaqusas a case study of the Alvik bridge.The finite element model was used to evaluate the difference betweennon-uniform and uniform creep and shrinkage with Eurocode 2.Further, a comparison between Eurocode 2 and Bažant’sB4 modelwas conductedfor non-uniform creep and shrinkage. The comparison aimedto evaluate the difference between industry and research specific calculation models, forthe effect of creep and shrinkage on deformations.A parameter study was alsoconducted to discern theeffect of parameters: ballast load, water-cementratio and conditions related to drying of concrete (relative humidity and perimeter exposed to air).Acomparison withthe deformationmeasurementsof theAlvik bridge was conductedto validate the resultsfrom the model.The results showed that there was a significant difference in the calculateddeformationof the bridge during the first ten years between analyses based onnon-uniform and uniformdistribution of creepand shrinkage,respectively.The non-uniformanalysis gave largerdeformations.However, only minor differences between the two approachescould be detected in the final deformation after 120 years. The main reason for the differences in the early behaviour is primarily caused by the differences in shrinkage rate between the top and bottom flanges. In these analyses, the top flange was assumed tonotdry out from the top. Thereby, the shrinkage rate of the top flange caused by one-way drying was similar to the bottom flange that was assumed to be exposed for two-waydrying.TheB4 model gave larger deformations compared to Eurocode2.This may be due to difference in the definition ofperimeter and surface. Eurocode 2 considers the perimeter exposed to air. The B4 model instead considers the entire surface area of the part.TheB4 model and Eurocode 2 show similar results asthe measurements. However, the B4 model gaveresults more consistent with the measurements.In the parameter study,lowerrelative humidity gave smaller deformations, since concrete shrinksquicker in dry ambient air.Varying the water-cement ratiodid not affect the deformationsnoticeably.Higher ballastheight gave significantly larger deformations. The height of the ballast was an uncertainfactor due to varying heights in the structural drawings of the case study. Accurate height of ballast is therefore important.Freivorbau broar har historiskt sett haft problem med kraftiga deformationer. Tidigare forskning föreslår att detta har orsakats av tjockleksskillnader i lådtvärsnitt och underskattning av krypning och krympning. Denna studie har undersökteffektenav ojämn krypningoch krympning på freivorbau broars långtidsdeformationer.Den ojämna krypningen och krympningen orsakas av skillnader i uttorkningshastigheterför lådtvärsnittets olika delar. En finitaelementmodell definieradesi programmet Abaqus som en fallstudie på Alviksbron.Modellen användes för att utvärdera skillnaden mellan ojämn och jämn krypning och krympning med Eurokod 2. En jämförelsemellan Eurokod 2 och Bažant’s B4 modellgenomfördes med hänsyn till ojämn krypningoch krympning.Syftet med jämförelsen var att utvärdera skillnadermellan byggnormeroch forskningmodeller med hänsyn till deformationer orsakade av ojämnkrypningoch krympning.Vidare genomfördes enparameterstudie för att urskilja effekten av parametrarna: ballast last, vatten-cement-tal och förhållanden relaterade till betongensuttorkning(relativ fuktighet och omkrets utsatt för luft).Deformationerna från finita elementmodellen jämfördes med uppmätta deformationer av Alviksbron.Resultaten visade att det fanns en signifikant skillnad i beräknad deformationunder de första tio årenmellan ojämn och jämn krypning och krympning.Ojämn krypning och krympning gav större deformationer.Mindre deformationsskillnad gavs dock i slutgiltig deformationefter 120 år. Den främsta anledningentill skillnaderna i deformation under de första tio årenär orsakat av skillnaderi krympningens hastighet mellan övre-och undre fläns.I analyserna antogs det att övre flänsen inte torkade ut från dess övre del.Därmed varkrympningens hastighetlikartad för övre flänsen som torkade ut åt ett håll, och undre flänsen som torkade ut åttvå håll.B4 modellen gav större deformationerjämfört med Eurokod 2.En möjlig förklaring för detta är definieringen av omkrets gentemot ytans area.Eurokod 2 definierar en omkrets utsatt för luft. B4 modellen definierar i stället arean av en yta, utan att ta hänsyn till om den är utsatt för luft.Även om B4 modellen och Eurokod 2 ger likartade deformationer, ger B4 modellen oftare deformationer som stämmer bättre överens med deformationsmätningarna av Alviksbron.Lägre relativ fuktighet gav mindre deformationer, eftersom betong krymper fortare i torrt klimat. Ändring av vattencementtal gav inte någon märkbar ändring i deformationer.Högre ballasthöjd gav betydligt större deformationer. Höjden på ballast var en osäker faktorpå grund av varierandehöjder i Alviksbrons konstruktionsritningar.Noggrann höjdbestämmelse av ballasten är därför viktigt.
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Farre, Checa Josep. "Simulation of cantilever construction of cable-stayed bridges taking into account time dependent phenomena." Thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-208405.
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In the design of cable-stayed bridges, the construction analysis is very important since the worst stresses are usually reached during the construction process. In addition, if the bridge is made of concrete, the effects of time dependent phenomena have great importance. Some commercial software are able to simulate the construction process, but one of their main drawbacks is that they simulate in a backward approach where creep is difficult to analyze. In this thesis a new criterion to define the Objective Service Stage (OSS) is presented which takes the constructive process into account. Tensioning operations are very expensive, so the main goal is to define the pretension forces in the stays such that only one pretension operation is necessary in each stay. Furthermore, an algorithm has been developed to simulate the construction process of cable-stayed bridges erected by cantilever method. This algorithm includes the creep effects into the structure. The Dischinger simplification, which is explained in this document, has been improved in order to better take into account the loading time and the age of the concrete in every stage. The creep simulation of the algorithm has been validated with some patch tests. The developed algorithm has been implemented in a full scale FEM model adapted from the Giribaile Dam project developed in 1990. In this study case, the new OSS criterion is implemented. Moreover, the axial forces in the stays, the bending moments, and the displacements are analyzed during the construction process and a comparison is carried out between two cases: with and without taking creep into account. With the new OSS criterion, the Objective Service Stage is achieved without taking the creep into account. However the creep effects, which are of huge importance in concrete bridges built by cantilever method, require the definition of an OSS which considers time dependent phenomena.
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丁強 and Qiang Ding. "Buffeting analysis of cable-supported bridges under turbulent wind in time domain." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 1999. http://hub.hku.hk/bib/B31238415.
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Al-Assaf, Adel. "Flutter analysis of open-truss stiffened suspension bridges using synthesized aerodynamic derivatives." Online access for everyone, 2006. http://www.dissertations.wsu.edu/Dissertations/Fall2006/Al_Assaf_122306.pdf.
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Ahmed, Elfatih. "Structural Design and Economic Analysis of Suspension Bridges Constructed Using FRP Deck." Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/471.
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Bridges built today are larger, but also lighter, more slender, and more efficient structures than they were a century ago. As the free span of future suspension bridges increases, so does the need for reducing dead loads. Using Fiber Reinforced Polymer (FRP) deck for suspension bridges is one way to achieve significantly lighter dead loads. Although the cost of FRP materials is more than double the cost of conventional concrete and steel deck, the hypothesis of this research is that the savings in the anchoring system and foundation and the reduction in weight of the main cables and suspenders will result in an overall cost reduction. It is also the hypothesis of this research that the use of FRP deck will impair the aerodynamic stability of suspension bridges. Significant studies have been performed on the use of FRP materials in bridge structures. The Federal Highway Administration initiated research on FRP composite bridge decks in the early 1980s, primarily focused on deck strength and stiffness. In addition, several research projects have been conducted for health monitoring and to assess the long-term performance of FRP materials in bridge construction. Overall, the results suggest that long-term structural response was consistent and well within acceptable strength and serviceability design limits. For the research described in this dissertation, a parametric study was performed considering several bridges of different spans, materials, soil conditions, and material unit prices to study the economic and aerodynamic implications of using FRP deck in suspension bridges . Two groups of suspension bridges with 200 m, 400 m, and 600 m free spans were designed, one group using a reinforced concrete deck and the other group using the much lighter FRP deck. Since soil conditions affect the design of the anchorage and the overall cost of the bridges, three different soil types were considered in this research. The three soil conditions that were considered in this research were sound rock, medium sand, and stiff clay. Then, the aerodynamic stability was examined for all of the bridges using Selberg’s approach. Three-dimensional finite element analyses was performed for each bridge to obtain the values for the torsional moment of inertia and the vertical and torsional frequencies. These values were used in Selberg’s equation to determine the flutter speed of each bridge. A linear elastic analysis was performed to validate the three-dimensional finite element analysis results. The predicted flutter speeds obtained from the linear elastic approach and the finite element approach were within 9% for all the spans and deck materials. The use of FRP deck reduced the predicted flutter speed of the 200 m span bridge, 400 m span bridge, and 600 m span bridges by 35%, 36%, and 37%, respectively. Sensitivity cost analysis was performed of the 200 m, 400 m and 600 m span bridges founded in three different soil types. The three soil types considered were sound rock, medium sand, and stiff clay. The maximum savings was realized in the case of the weakest soil with the least resistance to the main cables tension force: stiff clay. Consistent with the research hypothesis, the cost of the FRP deck is more than twice the cost of the concrete deck, yet the overall cost savings for using an FRP deck were 30% to 42% of the cost using a concrete deck depending on span length and soil conditions. While earlier studies have demonstrated that the life cycle cost analysis could be advantageous in the long term because it requires less maintenance, the findings of the research described in this dissertation showed that the use of FRP deck could result in a 30% to 42% reduction in initial construction cost.
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Karuna, R. "Structural modelling of suspension bridges with particular reference to the humber bridge." Thesis, Brunel University, 2002. http://bura.brunel.ac.uk/handle/2438/5191.
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The purpose of this research was to investigate the parameters that influence the structural behaviour of a specific suspension bridge, The Humber Bridge. Three finite element computer models of increasing complexity were created for the analyses. They were validated against field measurements for both static and dynamic loading, and good correlation was obtained. The programs were used to a) Assess the integrity of the bridge as a whole were three failures of certain individual elements, such as a hanger falling under vehicle impact; b) Determine the influence of the sizing of individual components, such as deck plate thickness or main cable diameter, on overall behaviour; c) ascertain the capability of the structure to cope with loading (traffic, wind orthermal), above the original design values; and d) consider the performance of the bridge had other configurations of hangers been adopted in the original design. From the results of this work, recommendations are made which could influence the future design of long-span suspension bridges.
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Beith, Jason Gordon. "The application of parallel computer technology to the dynamic analysis of suspension bridges." Thesis, University of Glasgow, 1997. http://theses.gla.ac.uk/1108/.
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This research is concerned with the application of distributed computer technology to the solution of non-linear structural dynamic problems, in particular the onset of aerodynamic instabilities in long span suspension bridge structures, such as flutter which is a catastrophic aeroelastic phenomena. The thesis is set out in two distinct parts:- Part I, presents the theoretical background of the main forms of aerodynamic instabilities, presenting in detail the main solution techniques used to solve the flutter problem. The previously written analysis package ANSUSP is presented which has been specifically developed to predict numerically the onset of flutter instability. The various solution techniques which were employed to predict the onset of flutter for the Severn Bridge are discussed. All the results presented in Part I were obtained using a 486DX2 66MHz serial personal computer. Part II, examines the main solution techniques in detail and goes on to apply them to a large distributed supercomputer, which allows the solution of the problem to be achieved considerably faster than is possible using the serial computer system. The solutions presented in Part II are represented as Performance Indices (PI) which quote the ratio of time to performing a specific calculation using a serial algorithm compared to a parallel algorithm running on the same computer system.
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Ding, Qiang. "Buffeting analysis of cable-supported bridges under turbulent wind in time domain /." Hong Kong : University of Hong Kong, 1999. http://sunzi.lib.hku.hk/hkuto/record.jsp?B21106538.
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Karoumi, Raid. "Response of cable-stayed and suspension bridges to moving vehicles : Analysis methods and practical modeling techniques." Doctoral thesis, KTH, Byggkonstruktion, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2764.
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This thesis presents a state-of-the-art-review and twodifferent approaches for solving the moving load problem ofcable-stayed and suspension bridges. The first approach uses a simplified analysis method tostudy the dynamic response of simple cable-stayed bridgemodels. The bridge is idealized as a Bernoulli-Euler beam onelastic supports with varying support stiffness. To solve theequation of motion of the bridge, the finite difference methodand the mode superposition technique are used. The second approach is based on the nonlinear finite elementmethod and is used to study the response of more realisticcable-stayed and suspension bridge models considering exactcable behavior and nonlinear geometric effects. The cables aremodeled using a two-node catenary cable element derived using"exact" analytical expressions for the elastic catenary. Twomethods for evaluating the dynamic response are presented. Thefirst for evaluating the linear traffic load response using themode superposition technique and the deformed dead load tangentstiffness matrix, and the second for the nonlinear traffic loadresponse using the Newton-Newmark algorithm. The implemented programs have been verified by comparinganalysis results with those found in the literature and withresults obtained using a commercial finite element code.Several numerical examples are presented including one for theGreat Belt suspension bridge in Denmark. Parametric studieshave been conducted to investigate the effect of, among others,bridge damping, bridge-vehicle interaction, cables vibration,road surface roughness, vehicle speed, and tuned mass dampers.From the numerical study, it was concluded that road surfaceroughness has great influence on the dynamic response andshould always be considered. It was also found that utilizingthe dead load tangent stiffness matrix, linear dynamic trafficload analysis give sufficiently accurate results from theengineering point of view.QC 20100511
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Karoumi, Raid. "Response of cable-stayed and suspension bridges to moving vehicles : analysis methods and practical modeling techniques /." Stockholm, 1999. http://www.lib.kth.se/abs99/karo0212.pdf.
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Gonzalez, Ignacio. "Application of monitoring to dynamic characterization and damage detection in bridges." Doctoral thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150804.
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The field of bridge monitoring is one of rapid development. Advances in sensor technologies, in data communication and processing algorithms all affect the possibilities of Structural Monitoring in Bridges. Bridges are a very critical part of a country’s infrastructure, they are expensive to build and maintain, and many uncertainties surround important factors determining their serviceability and deterioration state. As such, bridges are good candidates for monitoring. Monitoring can extend the service life and avoid or postpone replacement, repair or strengthening works. The amount of resources saved, both to the owner and the users, by reducing the amount of non-operational time can easily justify the extra investment in monitoring. This thesis consists of an extended summary and five appended papers. The thesis presents advances in sensor technology, damage identification algorithms, Bridge Weigh-In-Motion systems, and other techniques used in bridge monitoring. Four case studies are presented. In the first paper, a fully operational Bridge Weigh-In-Motion system is developed and deployed in a steel railway bridge. The gathered data was studied to obtain a characterization of the site specific traffic. In the second paper, the seasonal variability of a ballasted railway bridge is studied and characterized in its natural variability. In the third, the non-linear characteristic of a ballasted railway bridge is studied and described stochastically. In the fourth, a novel damage detection algorithm based in Bridge Weigh-In-Motion data and machine learning algorithms is presented and tested on a numerical experiment. In the fifth, a bridge and traffic monitoring system is implemented in a suspension bridge to study the cause of unexpected wear in the bridge bearings. Some of the major scientific contributions of this work are: 1) the development of a B-WIM for railway traffic capable of estimating the load on individual axles; 2) the characterization of in-situ measured railway traffic in Stockholm, with axle weights and train configuration; 3) the quantification of a hitherto unreported environmental behaviour in ballasted bridges and possible mechanisms for its explanation (this behaviour was shown to be of great importance for monitoring of bridges located in colder climate) 4) the statistical quantification of the nonlinearities of a railway bridge and its yearly variations and 5) the integration of B-WIM data into damage detection techniques.QC 20140910
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Grigorjeva, Tatjana. "Plieninių kabamųjų tiltų su standžiais lynais įtempių ir deformacijų būvis." Doctoral thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2007~D_20070402_152420-59302.
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Suspension bridges possess a number of advantages, allowing overlapping average and large spans. The basic disadvantage of suspension bridges can be considered their increased deformability, particularly under the action of non-symmetrical and local loads. Deformability depends, in general, on the kinematical character of displacements of a flexible suspension cable. Required rigidity of suspension bridges is achieved, by increasing the height, and consequently the weight of a stiffening girder, by diagonal suspenders or two-cable or combined prestressed systems. Reduction of kinematical displacements of the main cable can also be achieved by a reduction of the sag-to-span ratio, but the smaller the sag of a cable, the greater are the cable thrust forces and the required cross-sectional areas of the cables. One of the ways of suspension systems stabilization is giving certain bending stiffness to the suspension cables. Such structural solution with success is used in suspension roofs. With the aim to increase the stability of suspension bridges the author proposes to use the finite bending stiffness cables. The cables can be made of standard steel profiles or have composite sections. Conventionally, they are called as “rigid cables”. To verify this solution, the investigation on behavior of suspension bridges with rigid cables under loading has to be undertaken.
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Fuganti, Paloma Toledo. "Análise dinâmica de uma ponte com protensão no extradorso." Universidade Tecnológica Federal do Paraná, 2012. http://repositorio.utfpr.edu.br/jspui/handle/1/499.
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A busca por estruturas mais esbeltas, economicamente viáveis e esteticamente atraentes impulsionou a evolução e inovação no ramo de pontes. A protensão, tanto interna quanto externa, tem sido usada em larga escala e devido à sua eficiência, diversas técnicas foram desenvolvidas e utilizadas, como os estais. A ponte extradorso é uma estrutura que mantém características das pontes de viga reta construídas por balanços sucessivos, assim como de pontes estaiadas. A ponte com protensão no extradorso é uma estrutura recente e inovadora, que ainda é pouco utilizada no Brasil. O conceito desenvolvido em 1988 foi construído pela primeira vez em 1994 no Japão. Por serem estruturas com extensos vãos e que podem sofrer vibração excessiva, quando submetidas a carregamentos dinâmicos de grande intensidade, como os carregamentos móveis, é importante analisar o comportamento destas. A dinâmica das estruturas engloba a determinação das frequências naturais e dos modos de vibração naturais da estrutura, assim como os possíveis deslocamentos, esforços internos, velocidade e acelerações. Os modelos computacionais, usando o princípio do método dos elementos finitos, quando devidamente utilizados, podem representar valores muito próximos à realidade da estrutura em serviço. Este trabalho tem a intenção de analisar o comportamento dinâmico da ponte situada na TO-010, entre Miracema e Lajeado, inaugurada em 2011, quando submetida a diferentes carregamentos móveis e com diferentes velocidades, comparando-os com a análise estática.Searching for more slender structures, economically viable and aesthetically appealing drove and innovation in the bridges. Prestressing, both internal and external, has been used on a large scale due to its efficiency; several techniques have been developed and used, as the stays. The extradosed bridge is a structure that retains characteristics of straight girder bridges built by successive balances, as well as cable-stayed bridge. Prestressing extradosed is an innovative new structure, which is not widely used in Brazil. The concept developed in 1988 was first constructed in 1994 in Japan. Because they are structures with long spans and can suffer excessive vibration when subjected to dynamic loading of high intensity such as live loads, it is important to analyze their behavior. The dynamic of structures includes determining the frequency and mode of natural vibration of the structure, as well as the possible displacements and internal forces. Computer models, using the principle of the finite element method, when properly calibrated, can represent values close to the reality of the structure in service. This paper intends to analyze the dynamic behavior of the bridge located in the TO-010, between Miracema and Lajeado, inaugurated in 2011, when subjected to different moving load, and moving at different speed, comparing them with the static analysis.
5000
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Lucko, Gunnar. "Means and Methods Analysis of a Cast-In-Place Balanced Cantilever Segmental Bridge: The Wilson Creek Bridge Case Study." Thesis, Virginia Tech, 1999. http://hdl.handle.net/10919/35904.
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Different means and methods exist in the construction industry to erect bridge superstructures. In planning and execution of the complex construction operations the effects of the chosen erection method need to be considered to achieve a safe and economical process. Failures of bridges under construction have underlined the importance of this issue. Hence, constructability issues need to be considered from the very beginning of projects. Structural analysis mathematically models geometry, boundary conditions, and other structural details, material properties, and so-called actions and incorporates factors of safety. Aforementioned actions, i.e. loads or restraints of deformations may act only temporarily during construction, depending on the method and sequence of erection. However, these construction loads can create considerable stresses in the unfinished structure prior to completion when it still lacks additional redundancy against failure. Furthermore, time-dependent material properties such as creep, shrinkage, and relaxation play a major role, especially in segmental construction.
A case study is provided as an example of how constructability issues are dealt with in engineering practice. The Wilson Creek Bridge is a five-span cast-in-place concrete segmental bridge that was erected with Balanced Cantilever Construction. The bridge superstructure incorporated a camber to account for time-dependent deflections in final alignment.
Form travelers were used in an alternating manner about the bridge piers to construct cantilever arms that were finally connected at midspan. These travelers remained in place until the box girder segments had reached sufficient strength to be post-tensioned to their predecessors. Casting cycle duration on this project was one week.
Master of Science
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Ferreira, Luciano Maldonado. "Passarela pênsil protendida formada por elementos pré-moldados de concreto." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-16052006-172458/.
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Este trabalho aborda um tipo de passarela que está ganhando bastante notoriedade internacionalmente. Inúmeras obras vêm sendo construídas em diversos países, embora no Brasil ainda seja quase desconhecida. Basicamente, a estrutura é composta por cabos livremente suspensos, sobre os quais se apóia o tabuleiro formado por elementos pré-moldados de concreto. A protensão é utilizada como forma de enrijecer o conjunto. Dentre suas principais características, estão a rapidez e a facilidade de execução, a estética bastante agradável e o custo competitivo. Inicialmente, apresenta-se uma conceituação básica e um estado da arte. Em seguida, é estudado o comportamento estrutural da passarela. Alguns tópicos relativos à análise dinâmica e às fundações são brevemente comentados. Finalizando a dissertação, é feita uma aplicação numérica, enfatizando os aspectos que a diferenciam das estruturas convencionaisThis work treats a kind of pedestrian bridge that is standing out internationally. Several structures have been built in different countries, although they are almost unknown in Brazil. Basically, the deck is formed by precast concrete elements over free suspended cables. Prestressing is applied behind the abutments to provide rigidity to the structure. Quick and easy to assemble, aesthetically beautiful and the competitive cost are some of their main features. First, the basic concepts and a state of art are presented. Then, the structural behavior is studied. Some questions related to dynamic analysis and foundations are briefly commented. Ending the dissertation, an example is done, with emphasis to the aspects that make the stress-ribbon a non-conventional structure
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Permata, Robby. "Flutter Stabilization of Long Span Suspension Bridges with Slender Deck -Study on the Improvement of Aerodynamic Properties from Unsteady Pressure Characteristics Point of View-." 京都大学 (Kyoto University), 2014. http://hdl.handle.net/2433/189676.
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Swatzel, James Paul. "A partial differential equation to model the Tacoma Narrows Bridge failure." CSUSB ScholarWorks, 2004. https://scholarworks.lib.csusb.edu/etd-project/2631.
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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.
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Figueroa, López Rodiak Nicolai [UNESP]. "Um modelo matemático de suspensão de pontes." Universidade Estadual Paulista (UNESP), 2009. http://hdl.handle.net/11449/94216.
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Neste trabalho vamos estudar um modelo matemático que descreve as oscilações não lineares de uma ponte suspensa. Este modelo é dado por um sistema de equações diferenciais parciais que estão acopladas. Basicamente, estudaremos a existência e unicidade da solução fraca do sistema. Usaremos a teoria de operadores maximais monótonos para modelo linear e os semigrupos fortemente contínuos de contração para o modelo não linear.
In this work we study a mathematical model which describes the nonlinear oscillations of a bridge suspended. This model is given by a system of partial di®erential equations which are coupled. Basically, we study the existence and uniqueness of weak solution of the system. We use the theory of maximal monotone operators to model linear and strongly continuous semigroups of contraction for the nonlinear model.
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Figueroa, López Rodiak Nicolai. "Um modelo matemático de suspensão de pontes /." São José do Rio Preto : [s.n.], 2009. http://hdl.handle.net/11449/94216.
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Orientador: Germán Jesus Lozada CruzBanca: Alexandre Nolasco de Carvalho
Banca: Waldemar Donizete Bastos
Resumo: Neste trabalho vamos estudar um modelo matemático que descreve as oscilações não lineares de uma ponte suspensa. Este modelo é dado por um sistema de equações diferenciais parciais que estão acopladas. Basicamente, estudaremos a existência e unicidade da solução fraca do sistema. Usaremos a teoria de operadores maximais monótonos para modelo linear e os semigrupos fortemente contínuos de contração para o modelo não linear.
Abstract: In this work we study a mathematical model which describes the nonlinear oscillations of a bridge suspended. This model is given by a system of partial di®erential equations which are coupled. Basically, we study the existence and uniqueness of weak solution of the system. We use the theory of maximal monotone operators to model linear and strongly continuous semigroups of contraction for the nonlinear model.
Mestre
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Lima, Vanessa dos Santos. "Projeto de superestruturas de pontes de concreto protendido aplicando a técnica de balanços progressivos." Universidade Federal de São Carlos, 2011. https://repositorio.ufscar.br/handle/ufscar/4657.
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Previous issue date: 2011-05-16This dissertation deals with main considerations on design of bridge superstructures, applying the cantilever balanced technique, bringing a procedure to be followed during pre-dimensioning this type of bridge. Presents the literature review used as the basis to dissertation, with the theories already studied on the subject. Based on these studies is drawn up the roadmap, involving the step of choosing the geometry, defining the structural scheme, the calculation of structural strain, calculating the losses of prestress, predimensioning of the prestressing steel considering the ultimate limit state and the service limit state, evaluation of the moment of closure and some important items for the detail section with steel. A numerical example is solved to illustrate the use of the concepts presented throughout the dissertation. Ends with considerations on the results obtained in the example and work and presents suggestions for future work.
Esta dissertação trata das principais considerações num projeto de superestruturas de pontes aplicando a técnica em balanços progressivos, fornecendo um procedimento para pré-dimensionamento deste tipo de ponte. Apresenta-se a revisão bibliográfica utilizada como base para dissertação, com as teorias já estudadas sobre o assunto. Com base nestas pesquisas elaborou-se um procedimento, envolvendo a etapa de escolha da geometria, definição do esquema estrutural, cálculo dos esforços solicitantes, cálculo das perdas de protensão, pré-dimensionamento da armadura de protensão levando em consideração o estado limite último e o estado limite de serviço, avaliação do momento de fechamento e alguns itens importantes para o detalhamento da seção com armadura. Um exemplo numérico é resolvido de forma a ilustrar a utilização dos conceitos apresentados ao longo da dissertação. Finaliza-se com as considerações sobre os resultados obtidos no exemplo e no trabalho e apresenta-se sugestões para trabalhos futuros..
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Costa, Leandro Malveira Ferreira. "Investigação numérica de modelos de turbulência no escoamento do vento em pontes suspensas." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3146/tde-05032018-145557/.
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Estudos sobre a instabilidade aeroelástica em estruturas de pontes suspensas têm adquirido relevante destaque no âmbito das pesquisas em engenharia do vento nos últimos anos, haja vista que as definições resultantes dessa análise apresentam informações essenciais ao projeto, cálculo e concepção desse tipo de estrutura. Considerando que os escoamentos ao redor de pontes suspensas apresentam características turbulentas, o conhecimento acerca desse fenômeno torna-se fundamental para a análise da interação vento-ponte, estabelecendo a turbulência como uma importante e complexa vertente dentro dessa pesquisa. Nesse contexto, o presente trabalho visa contribuir com o tema através da análise numérica da ação do vento na seção transversal do tabuleiro de pontes suspensas, verificando seu comportamento quando estiverem submetidas à ação dos esforços provenientes do vento na interação de um escoamento turbulento com o tabuleiro da ponte. No trabalho foi investigada a atuação dos esforços aerodinâmicos na estrutura da ponte, ensejando na obtenção dos coeficientes aerodinâmicos de arrasto, sustentação e momento. Também foi analisado o comportamento do tabuleiro para o surgimento das vibrações induzidas por vórtices, permitindo o cálculo da frequência de desprendimento de vórtices e determinação do número de Strouhal. No que tange aos esforços aeroelásticos para o estudo específico do drapejamento (flutter), foram avaliadas as amplitudes de deslocamentos torcionais para o cálculo e obtenção da velocidade crítica do vento que acarreta o fenômeno do flutter. Juntamente com as análises aerodinâmicas e aeroelásticas da seção transversal da ponte, diferentes modelos de turbulência foram aplicados nas simulações para se estabelecer uma análise comparativa entre os escoamentos. As simulações computacionais desenvolvidas e apresentadas neste trabalho foram realizadas com auxílio de um programa de CFD (Computational Fluid Dynamics). Os modelos de ponte utilizados no trabalho foram o da ponte suspensa Great Belt East, localizada na Dinamarca e da ponte estaiada Sunshine Skyway, localizada nos Estados Unidos. Para validação da técnica computacional, os resultados das simulações foram comparados com dados numéricos e experimentais disponíveis na literatura.Researches about aeroelastic instability in long span suspension bridges have been consistently the focus in wind engineering field in recent years, therefore the definitions from that study present essential information to design and construction of this type of road structure. Considering that fluid flows around bridges show some turbulent features, the knowledge about turbulence become critical for this wind-bridge interaction analysis, establishing the turbulence modeling study as an important and complex part within that research. According to this context, the meaning of this research was to contribute with numerical analysis of wind effects on a suspension bridge deck, verifying its behavior when this model is subjected to the action of wind loads from a turbulent fluid flow. The bridge aerodynamic behaviour was investigated and aerodynamic coefficients of drag, lift and moment were calculated. Flow induced vibrations were also analyzed for the bridge deck model, allowing it to obtain the vortex shedding frequency and Strouhal number. With regard to aeroelasticity and focusing on flutter study, the amplitudes of torsional displacements were evaluated as well as the analysis of critical wind velocity that causes flutter instabilities. Along with aerodynamic and aeroelastic analysis of the bridge deck cross sectional, fluid flow features were studied and compared applying several turbulence models to simulations. The numerical approach developed and shown in this work was performed by CFD (Computational Fluid Dynamics) software. The bridge deck models used at this dissertation were the Great Belt East suspension bridge, located in Denmark and the Sunshine Skyway cable stayed bridge, located in USA. In order to validate the computational technique, simulation results from this research were compared with numerical and experimental test data available in papers and literature.
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Koláček, Jan. "Analýza půdorysně zakřivených závěsných a visutých lávek." Doctoral thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-392289.
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The aim of the doctoral thesis focuses on the static and dynamic analysis of a plan curved cable stayed and suspension pedestrian bridges suspended on a single-side of their deck. The first part of this thesis deals with an analysis of the equilibrium in the transversal direction of a deck cross section suspended on a single-side. The section and its arrangement should be designed so that the torsion caused by the deck self-weight and dead load would be minimal. This theory was verified on a simple study of a single-sided suspended section with and without prestressing. Second part of the thesis deals with the design of a study of a plan curved cable stayed pedestrian bridge. The study describes in detail a finding of an initial state of the structure and the static and dynamic analysis performed by software ANSYS. The static analysis describes the response of the structure on the most frequent variable loads only, but not design of dimensioning according to the valid codes. The dynamic analysis verifies a predisposition of the structure to the vibrations and others harmful oscillation effects. The next objective of the thesis was to design a study of a plan curved suspension pedestrian bridge suspended on a single-side. A process of an analysis of these structures has not found in any available references. Especially, the finding of an initial state of a suspension cable has not been documented anywhere and by anybody. The study was analyzed with the same geometry as the cable stayed variation in order to compare both structures. The static and dynamic analysis was performed, too. The last part of the thesis describes the verification of structural solution on a fully functional model in a 1:10 scale, proposed process of the initial state finding, response of the structures on the loading and ultimate load test. The important step is the comparison of the results of the completed physical model and the calculation model.
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Huang, Bo-Ru, and 黃鉑茹. "Study and Analysis of Extradosed Bridges with Cantilever Construction Monitoring." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/8me3xy.
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碩士國立臺北科技大學
土木工程系土木與防災碩士班（碩士在職專班）
105
Because of the climate change and the extreme climate of Taiwan, there are Typhoons and torrential rain triggered floods, landslides in addition to the earthquake disaster in Taiwan. The natural disasters make peoples life and property at risk. Therefore, when designing the bridges adopt the span bigger than river width, decreasing the riverbed falling pier, avoiding the channel contraction and compound cross-sectional channel principle are the basic of the design bridges. Using Cable-stayed Bridge and Extradosed Bridge which are beautifully shaped bridges and functional at the same time. So, to avoid the aforementioned problem, the cantilever method is used to increase the span length. This article uses construction analysis, numerical analysis, computer analysis, and in-situ measurements to analyse extradosed bridge construction by cantilever method. From Surveying and detailed monitoring, and the geometry of the bridge is established through AutoCAD and then inputted into Midas civil structural analysis commercial software to analyse and compare the results. At time of brige construction, the measurement and monitoring results of northern west coast expressway temporary engineering office is used to compare with the finite element model results. At the same time, build the basic database of bridge which concluding current situation and basic archives management of bridge construction. The accuracy of analysis and construction method correctness can be presented at the first half life cycle planning.Hopefully this paper can serve as a reference for the maintenance crew, and serve as a training for bridge engineering and technical personnel This paper shows the accuracy of the Midas civil software and it is effectiveness in analysing deformation of extradosed bridge during construction. It also can be used in structural design of bridge.
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Mermigas, Konstantinos Kris. "Behaviour and Design of Extradosed Bridges." Thesis, 2008. http://hdl.handle.net/1807/17203.
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The purpose of this thesis is to provide insight into how different geometric parameters such as tower height, girder depth, and pier dimensions influence the structural behaviour, cost, and feasibility of an extradosed bridge.
A study of 51 extradosed bridges shows the variability in proportions and use of extradosed bridges, and compares their material quantities and structural characteristics to girder and cable-stayed bridges. The strategies and factors that must be considered in the design of an extradosed bridge are discussed.
Two cantilever constructed girder bridges, an extradosed bridge with stiff girder, and an extradosed bridge with stiff tower are designed for a three span bridge with central span of 140 m. The structural behaviour, materials utilisation, and costs of each bridge are compared. Providing stiffness either in the girder or in the piers of an extradosed bridge are both found to be effective stategies that lead to competitive designs.
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Machado, Catarina da Cunha Nunes de Sá. "Analysis of self-anchored and ground-anchored suspension bridges." Dissertação, 2014. https://repositorio-aberto.up.pt/handle/10216/73247.
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Machado, Catarina da Cunha Nunes de Sá. "Analysis of self-anchored and ground-anchored suspension bridges." Master's thesis, 2014. https://repositorio-aberto.up.pt/handle/10216/73247.
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Cheng, Tsun-Ti, and 鄭存迪. "Study on Cantilever Erection by Cable-Supported for the Steel Bridges." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/ae38ww.
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碩士國立臺北科技大學
土木與防災研究所
98
Serving as a base of investigation on each construction stage, the structural analysis of the cantilever erection for the steel bridges using cable-supported method benefits the engineers a good control on minimizing the possible error induced by erection. Unfortunately, little qualified commercial software could fulfill the requirements for such kind of analysis. To overcome this awkward situation, this thesis reviewed the theoretical background and completed the analysis just through the common software unqualified. The influence matrix relating to each erection stage of the bridges was formulated to get the structural response and sequentially superimposed with those in previous stages. By this method, a series of structural analyses for the erection stages reverse to the sequence of actual construction work, known as the backward analysis, was conducted. One case of a bridge with steel box girders and the other one of a steel cable-stayed bridge in Taiwan were studied and discussed. The result obtained was compared with that from the qualified software of MIDAS/CIVIL. A consequence of little discrepancy between these two results can be found. It shows that this thesis helps the engineers do the complicated analysis even through the software without the function of construction analysis.
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Tao, Ming-Tai, and 陶明泰. "A Blackboard Expert System for Preliminary Design of Balanced Cantilever Bridges." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/89053468408999810848.
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碩士淡江大學
土木工程研究所
83
Since the fast development of computer technology and its immense popularity, computers have been the most important to- ol for design engineers. However, traditional algorithmic pro- gram is difficult to represent experience-based knowledge in a design domain. Therefore, the use of knowledge-based expert s- ystems in design has become a research and development trend, and its initial success justified the promise of knowledge-ba- sed systems in computer-aided design. Typical expert systems use heuristic rules and rule chain- ing to solve problems. Rule- based expert systems cannot fully satisfy the knowledge representation and inference procedur r- equired in structural design because of its limited knowledge representation schema. In order to open a new window for the application of expert system technology in structural design, this research examined the finer features provided by blackbo- ard systems, which include explicit representation, opportuni- stic reasoning and clear separation of control and domain kno- wledge. The thesis emphasizes the establishment of the structural design blackboard architecture and demonstration of its adequ- acy in structural design. A domain knowledge base for balanced cantilever bridge design was built to test and evaluate the b- lackboard system. Balanced cantilever bridge design was selec- ted as the demonstration domain based on its representative in structural design, and it successfully demonstrated the poten- tial of blackboard systems in structural design.
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Sloane, Matthew Jake Deeble. "Fire Effects on Suspension Bridge Main Cables: Methods for Determining Both Temperature and Strain Distributions Within an Exposed Cable." Thesis, 2017. https://doi.org/10.7916/D8930TJZ.
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Fire resistance design and analysis is an under-studied and under-codified area of bridge engineering. With the lessening of conservatism in bridge design, the aging or our bridge infrastructure, and the increase in the ground transport of highly-flammable and -combustible materials, it is essential that the bridge engineering community better understand and incorporate methods for modeling the effects of fire on bridges. Typical fire resistance analysis looks at the response of individual structural components. Analysis for the component of a bridge is nowhere more important than for that of the main cables of suspension bridges. As such, we will survey and introduce the necessary analysis techniques to provide the bridge engineering community with the knowledge and tools to understand fire modeling and both rapidly and accurately assess their effects on suspension bridge main cables.
The work of this dissertation is twofold. In the first portion, we address proper fire modeling techniques for bridge conditions and apply them in a sequential thermal-mechanical analysis of a three-dimensional model main cable with thermally-dependent material and mechanical properties. Although fire modeling has been addressed in a variety of scenarios, including extensive studies for building design and analysis as well as tunnel design and analysis, the types of fires, fire geometries, and air conditions associated with bridge fires vary drastically. Our work identifies the time to failure for our particular main cable example and subsequently compares both the temperature and strain distributions for temperature-dependent and temperature-independent models.
Although the three-dimensional analysis is complete, we hope to emulate and expand on the work done in the building fire engineering community and bring to the literature methods to produce significant two-dimensional temperature distributions for when a main cable component is either partially or fully-exposed to fire. As such, the main fire modeling analyses mentioned in the previous paragraph lay the groundwork for our pursuit of closed-form analytical solutions necessary to rapidly and accurately assess the time-dependent temperature distribution within a cable cross-section exposed to fire. These solutions are formed with different approaches depending on the fire scenario in question. They include a separation of variables (eigenfunction) approach, sinusoidal transforms, Laplace transforms, Green's function solutions, and a semi-analytical hybrid method. We validate each of the approaches numerically using three different fire models.
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LIN, YI-SYUAN, and 林怡萱. "Study on the Flow and Safety for Suspension Bridges – A Case Study of San-Chi Suspension Bridge." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/wjcbgs.
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碩士中華大學
運輸科技與物流管理學系
107
In the past way, suspension bridges, SB, were the important way to cross river. People pass it one by one. Until 2005, Tan-Ti SB was built at Nan-Tou. Tan-Ti SB has a long spend, beautiful scene and special structure, it makes people stand on bridge to see the scene. Such behavior has changed SB functional. One by one pass by, not stay at bridge. In this research, we will study on stay at bridge will makes what important facts for SB safety. Moreover, government more care about the total peoples, not The Peoples Per Square Meter, TPPSM. But TPPSM is the most important fact than the total peoples. We will compare many country standards, and analysis our standards to prove it. And then, we offer a case, Kan-Der SB at San Chi was crushed to explain the most important fact, TPPSM. Finally, we visit 8 experts in construction and SB inspection, and got some correspond results to approve our research.
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Lo, Yuan-Chun, and 羅元駿. "Aerodynamic Analysis of Pedestrian Suspension Bridges Subject to Large Angles of Wind Attack." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/60099613817537424597.
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碩士淡江大學
土木工程學系碩士班
104
Some cable-supported bridges have been designed or built in mountainous areas in Taiwan. Due to the complex terrain, not only the variations of wind speed but also the possibility of large angle of wind attack should be considered in the investigations of the aerodynamic responses of the cable-supported bridge built in these areas. The angle of wind attack for the bridge built in the complex terrain has been found in the literature as large as fifteen degrees or more. At the large angle of wind attack, the difficulties have risen in full bridge model tests. Therefore, the measurement of the section model responses is the only way to investigate the aerodynamic behavior of the bridges built in the complex terrain. Effects of large angles of wind attack on the flutter wind speeds and buffeting responses of bridges are investigated in this thesis. A typical pedestrian suspension bridge is chosen as the example for the investigation. The experimental results show that the flutter wind speeds decrease with the increases of angles of wind attack. The trend is more obvious as the angle of wind attack is larger than 6.5 degrees. The flutter wind speed may decrease 40% as the angle increases from 6.5 degrees to 8.5 degrees. As we expected, the increases of turbulence intensities will increase the flutter wind speeds for all angles of wind attack. The increase of the torsional -vertical frequency ratio of the section model will increase the flutter wind speed significantly. The results also show that the increase of angles of wind attack increase the responses buffeting in all directions. At the wind speed of 30m/s, the vertical response at the angle of 10 degrees increase 84% compared to that at the angle of zero degree. The large amount increases are also found in drag and torsional directions. Since the large angles of wind attack may occur for the bridges built in the complex terrain, the aerodynamic behavior of these bridges should be carefully examined.
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Yi-Chao, Li, and 黎益肇. "Investigation on aeroelastic behavior of suspension bridges with ertain simple geometric cross-sections." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/53045632482923523406.
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博士國立中興大學
土木工程學系
93
A numerical method is developed to predict the dynamic behavior of a suspension bridge under wind action in a two dimensional sense. In particular, the behavior of a vibrating deck with six simple geometric cross-section is examined. The simulations contain two parts of computations, which are performed alternatively during the calculation process. The solutions of the instantaneous flow field and the deck motions are considered the basis to analyze the problem of deck instability. Wind tunnel measurements are conducted in parallel to measure the response of a sectional bridge model. The vertical and torsional deflections of the model are measured under various wind speeds with several selected attack angles and eccentric mass. The results are used to confirm the accuracy of the numerical predictions. Results show that the numerical predictions of the structural response agree well with those from the experiments, indicating that the proposed method is capable of predicting the deck motion with good accuracy. Based on the time-series numerical results, finally, the interactive behavior of the vibrating deck is examined extensively.
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Tsai, Jeng-Lin, and 蔡政霖. "An Investigation into the Static and Dynamic Mechanical Behaviors of Self-anchored Suspension Bridges." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/60452433622991991730.
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博士中華大學
土木與工程資訊學系(所)
98
The suspension bridge is characterized by its long span and elegant structural shape. Traditional suspension bridges often span over long distances with the main cables earth-anchored at two ground structures near the abutments. As the length of the span decreases, the cost to anchor the main cables rises and eventually reaches a point where the construction cost of the suspension bridge significantly exceeds that of other forms of bridges. In fact, if the main cables of the suspension bridge are directly anchored onto the main girder, great savings on the anchorage can be achieved. Suspension bridges with this type of anchorage are referred to as a self-anchored suspension bridge. The self-anchored suspension bridge is increasingly favored in construction due to its aesthetic appearance, economic benefits, and strong adaptability to the local topographical and geological conditions. It has become a very competitive candidate for bridges that are used to cross rivers, or a small bridge with a short span in urban areas. A number of self-anchored bridges have already been constructed abroad. Even though the only difference between the self-anchored suspension bridge and the traditional earth-anchored suspension bridge is that the locations of the main cables’ anchorages are different, the load-bearing characteristics of the structure and the construction method are subjected to significant changes. The self-anchored suspension bridge does not only inherit the mechanical characteristics of the traditional suspension bridge, but also possesses its own unique static and dynamic features due to the large axial force in the main girder. In order to gain a deeper understanding of these features, this study analyzes and discusses the responses of the self-anchored suspension bridge under static loading, its ultimate load-bearing capacity, and its responses under seismic loading. The main contents and outcomes of this research are as follows. (1)Analyze and discuss what effects the breakage of hangers will have on the response of the self-anchored suspension bridge under static loading at various locations: The results indicated that when the hanger broke, the cable force in the adjacent hangers increased noticeably. Moreover, the breakage of the hanger at the mid-span of the main span had the largest influence on the maximum negative bending moment. When the hanger that lies in the vicinity of the tower broke, evident changes in the internal forces of the self-anchored suspension bridge and changes in joint displacements were observed. (2)Analyze and discuss the ultimate load-bearing capacity of the self-anchored suspension bridge and its failure process: The influences of what the changes in strength or stiffness of substructures and the influences of broken hangers will have on the ultimate loading-bearing capacity and the failure process of the bridge was investigated. The results showed that changes in the strength or stiffness of different substructures had effects on the ultimate load-bearing capacity of the self-anchored suspension bridge to various extents. While the ultimate load-bearing capacity was clearly affected by the breakage of some hangers, the concurrent breakage of a number of these hangers could lead to the immediate failure of the bridge. (3)Analyze and discuss earthquake responses of the self-anchored suspension bridge by performing response spectrum analysis and time history analysis. In addition, the influences of geometric changes, the changes in the stiffness of substructures, and the influences of the broken hangers on the earthquake responses are also studied. The analysis results indicate that the self-anchored suspension bridge also keeps some of dynamic characteristics of the earth-anchored suspension bridges, which has relatively long low-level natural vibration periods, large vertical displacements, possible beam lowering, and possible damage of the expansion joints. Moreover, the change in the stiffness of the main girder had the largest influence on the vibration frequency, the internal forces in the direction along the main girder under earthquake events, and on the joint displacements. The change in the stiffness of main cables had the largest effect on the internal structural forces and joint displacements under vertical earthquake actions. (4)Analyze and discuss the ductile earthquake responses of the self-anchored suspension bridge through time history analysis and study the earthquake responses after the installation of the metal dampers: The effects of geometric and stiffness changes of substructures and the broken hangers on the bridge’s earthquake responses are also studied. The results suggested that by considering the ductile earthquake responses, the seismic loading on the bridge can be lowered, and consequently, the seismic resistance of the self-anchored suspension bridge was improved. However, joint displacements were observed to have increased remarkably. Furthermore, metal dampers can consume a large amount of seismic energy. As a result, the bending moment at the base of the tower was reduced noticeably, and the inflections of the main girder and the tower could be better controlled. This therefore reduces the possibility of beam lowering and causing damage to the expansion joint devices.
45
Wu, Wei-Hao, and 吳偉豪. "On the Feasibility of Using 3-D Laser Scanner to Monitor Deformation in Suspension Bridges." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/19233646276741882984.
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碩士清雲科技大學
土木與防災研究所
96
This study discusses the causes of main cable sag monitoring on suspension bridges. Although this amount does not seem significant, the main cable sag transition phenomenon at a scope of L/5 to L/4, and the scope can be regard as a rigid bodies, beside there are many instruments of survey can recognize the mm levels. Therefore it is possible by using the cable sag to estimate the damage of main cable. By using 3-D Laser Scanner 3-D point clouds information regarding the suspension bridges of main cable can be instantaneously obtained. Therefore, may apply in this research confirmation, the analysis case demonstrated that this method has the discussion value. The experimental resulted are also with theoretical analysis match.
46
WAN, CHEN-CHUNG, and 萬正忠. "Visual Inspection and Assessment of Pedestrian Suspension Bridges—A Case Study of Taroko National Park." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/n6f3un.
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碩士大漢技術學院
土木工程與環境資源管理研究所
106
Pedestrian suspension bridges （PSBs.） are mostly built in remote mountain areas or popular tourist sites. With changes in the lifestyles of people in Taiwan, traveling has become the most popular form of recreation. Taroko National Park has 11 PSBs, and ensuring the safety of their users is crucial. Therefore, it is necessary to establish a visual inspection standard. By conducting a comprehensive quantitative assessment of the PSBs under its purview, management units can establish a relevant data base beneficial for formulating and implementing PSBs maintenance and management strategies, thereby ensuring users’ lives and safety. Based on the characteristics of PSBs, this study proposed a visual inspection and assessment method comprising simple tables for inspectors to fill in during inspection and assessment of PSBs in use. Each inspection item is weighted, and the scores the bridges receive serve as references for prioritizing PSBs maintenance. The assessment principles based on quantified scoring can yield reasonable and objective results. Digitized assessment result collected under the same standards will assist the management unitsin conducting panel studies on PBSs. By comparing assessment results from multiple PBSs, they can carry out the most urgent maintenance on a limited budget.
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Lin, Bing-Hong, and 林炳宏. "Study of impact effects on bridges using suspension vehicle models by substructure dynamic condensation method." Thesis, 1993. http://ndltd.ncl.edu.tw/handle/77857980641480593182.
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Wang, Yung-Kuan, and 王詠寬. "Research on Long-Term Deflection of Large-Span Prestressed Concrete Segmental Bridges Built by Cantilever Method in Taiwan." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/se29v3.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
106
In recent years, the old bridges around the world, especially the prestressed concrete box bridges constructed by the cantilever method, are facing a serious problem. The vertical displacement obtained by long-term monitoring of the central hinge of the bridge far exceeds the range estimated by the initial design. The indeterminate structural system caused by the rigid connection of the new type of bridge is also unable to grasp the influence of concrete creep and shrinkage, and cannot grasp the deflection and internal stress in the bridge. Through monitoring data, it is found that the trend of long-term displacement of bridges will not gradually slow down and stabilize, but will continue to develop toward a fixed slope under logarithmic time coordinates. Excessive deflection will cause the vertical displacement of the central hinge and the difference in the slope of the hinge angle to be too large, causing the impact of the vehicle due to the subsidence, thus causing concerns about the serviceability and safety of the bridge, which may eventually shorten the service life. The requirements for earlier retrofit or eventual demolition of bridge will impose a major burden on the government and society. The reasons for the long-term deflection of the bridge are mainly attributable to the creep of the concrete, the differential shrinkage and differential creep of the box girder section, and the loss of prestress caused by creep and shrinkage. At present, the prediction formulas for concrete creep and shrinkage specifications in various countries are generally underestimated in the trend of concrete deformation for several decades. The characteristics of concrete materials in Taiwan are also different from those in foreign countries. It is not appropriate to directly adopt foreign prediction formulas. In addition, the local engineering community mostly uses the two-dimensional beam element model analysis, which cannot truly reflect the phenomenon that the drying creep and the drying shrinkage rates are different due to the thickness variation of the top and bottom plates and the webs. Therefore, this study applies different creep and shrinkage prediction formulas for concrete, including ACI 209R, CEB MC10, GL2000, Model B4 and locally developed Model B4-TW formulas, and Yuan-Shan Bridge of the national highway No. 1 is used for study. A three-dimensional finite element model, which can take account of the phenomenon of different shrinkage and creep rate caused by geometrical scale differences, was developed to evaluate the vertical displacement of the location at central hinge and the loss of prestressed force. Through the comparison between the analysis results and the monitoring data, the differences between the prediction formulas and the influence of the extension from the materials to the real structure are discussed, a long-term deformation analysis model for concrete bridges suitable for Taiwan is developed. In addition to the assessment of the safety of existing old bridges, it can also provide reference for future retrofit, decommissioning or alternative planning for bridges. For new bridge design, a complete method for analyzing the long-term deformation and assessment of the useful service life of concrete bridges was established. The method will enable the engineering community to more clearly grasp the long-term displacement trend of Taiwan''s concrete bridges and its prestressed losses, and to facilitate safety monitoring and evaluation, and timely corresponding strengthening measures to avoid disasters, and to extend the service life of concrete structure during the design and maintenance phase to achieve the sustainability.
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Brügger, Adrian. "On the Boundary Conditions and Internal Mechanics of Parallel Wire Strands." Thesis, 2017. https://doi.org/10.7916/D832074B.
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This dissertation analyzes the internal mechanics of parallel wire strands as found in the main cables of suspension bridges. Parallel wire strands of reduced order (7-wire, 19-wire, and 61-wire strands made of steel and aluminum) are fabricated and subjected to various boundary conditions and external loads (tension, clamping, twist, etc.). Neutron diffraction is used as an elastic strain measurement tool for its ability to penetrate bulk materials and/or layers of a multi-body system without disturbing the sample. Firstly, this thesis aims to quantify the development length – the distance over which a broken wire within a strand regains near-full service strain – as a function of various boundary conditions and failure scenarios. The feasibility of using neutron diffractometers to measure in situ elastic strains on civil-engineering-scale samples under both tensile load and radial confinement is validated using strands fabricated from steel bridge wire. Results from various 7-wire strands indicate that friction and mechanical interference on the microscopic level play a significant role in the load partitioning. Furthermore, wires that have been broken – either pre-cracked or fractured live and in situ during tensile loading – are capable of regaining significant stresses from their neighbors over a distance of tens of centimeters. The contribution of both friction force and mechanical interference on elastic strain redevelopment in broken wires should be included in analytical models designed to simulate failure processes. The second part of this thesis aims to measure the internal mechanics of larger parallel wire strands in response to various confinement (clamping) forces. 19 and 61 aluminum wire strands are fabricated and the internal strains of all constituent wires mapped in three orthogonal directions under various clamping loads. The strain distributions for both 19-wire and 61-wire strands show a surprising degree of heterogeneity. An increase in clamping force homogenizes the distribution to a degree, but only at unfeasibly high clamping forces. The results suggest that microscale variations in wire diameter dominate the internal mechanics of parallel wire strands. The stochastic distribution of wire sizes due to manufacturing tolerances throughout a strand cross-section creates a randomly ordered network of over- and under-sized wires. This imperfectly packed lattice results in large wire-to-wire variations in clamping constraint. The up-scaling in strand size from 19 to 61 wires increases the resolution of the experiment but does not reduce the heterogeneity of the strain distribution. Ergo, the assumption of perfect hexagonal packing in parallel wire strands is weak, and mean field distributions do not accurately describe the internal mechanics of such structures.
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Karanci, Efe. "Modeling Corrosion in Suspension Bridge Main Cables." Thesis, 2017. https://doi.org/10.7916/D8RB7H05.
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Accurately determining the current state of a suspension bridge’s main cables is a critical component to reliably assessing the safety of the bridge. The primary cause for the deterioration of cable strength with time is universally recognized to be the corrosion of high strength steel wires, which together comprise the main cable. Hidden from view by the cable wrapping, this corrosion often goes undetected for years and is typically only discovered during costly and intrusive inspections. Furthermore, current inspection methods provide an incomplete picture of the variation in wire condition across the cable cross section. As a result, cable strength estimation techniques that rely solely on inspection data introduce a considerable degree of uncertainty. Finally, a method has not been developed for estimating the continuing decline in cable strength due to ongoing corrosion. A recent direction in research attempts to address the shortcomings of current inspection methodologies and the intent of this thesis is to further build upon these findings.
In these recent studies, environmental conditions inside main cables are monitored to obtain information regarding the corrosive nature of the cable’s internal environment. The first goal of this thesis is to further this research direction by introducing a corrosion rate model for bridge wires that relates the monitored environmental parameters within a cable to the corrosion rate of bridge wires. Initially, temperature, relative humidity, pH, and Cl- concentration have been identified as the most relevant variables for predicting the corrosion rate of a bridge wire. By applying machine learning methods to a corrosion dataset in conjunction with these monitored environmental inputs, a long term corrosion rate model for bridge wires has been developed that is capable of capturing variability associated with these environmental parameters.
This long term corrosion rate model is then applied to establish a methodology that will allow bridge owners and engineers to estimate the remaining strength of a main cable at any point in time. This is accomplished through the use of continually monitored environmental parameters which are input into the corrosion rate model. Incorporating the long term corrosion rate model developed in this thesis with current strength estimation techniques, the methodology presented in this thesis for the estimation of the remaining strength of suspension bridge cables may be readily adapted to other bridges and can be used to complement the current best practices for bridge inspection.