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1
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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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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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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Demartini, Christopher J. "Strength and durability of the Story Bridge approach spans." Thesis, Queensland University of Technology, 1992. https://eprints.qut.edu.au/36060/1/36060_Demartini_1992.pdf.
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A great number of reinforced concrete bridges in Australia are in excess of 30
years old and beginning to show signs of distress. The vehicle loads carried by
these structures have increased since their construction and will continue to
increase in the future. A rational procedure for inspection, testing and analysis
of these bridges is vital if this important national asset is to be managed
effectively and the useful life of these structures economically extended.
The Story Bridge provides a major traffic corridor over the Brisbane River. It
is now over 50 years old and beginning to show signs of distress. The author
has undertaken a detailed procedure of testing, inspection and analysis of the
approach spans to this structure. The procedure formulated for the Story
Bridge can be effectively applied to other reinforced concrete bridge structures.
The major mechanisms of concrete corrosion have been identified and methods
to test for these in concrete stn,ictures detailed. These testing methods have
been applied in the investigation of the approach spans to the Story Bridge.
Several applicable structural analysis techniques have been described and
implemented in the analysis work undertaken. Test loading of the structure
was carried out using two 38 tonne test vehicles and employing a computer
based data logging system for data collection. The results of the test loading
were used to calibrate the various analytical models used in the investigation.
The results of the investigation of the approach spans to the Story Bridge have
shown that the major problems are corrosion of reinforcement with associated
concrete spalling at expansion and construction joints and significant
carbonation of the concrete in the structure. The causes of these problems and
remedial measures to economically extend the useful life of the structure have
been formulated.
The work undertaken highlighted the need for improved design techniques with
respect to limiting the number of joints in bridges, and also the need for further
research into the long term behaviour of coating systems for the protection of
concrete against carbonation. Also highlighted was the need for a national
mobile testing facility for bridges to enhance the ability of public authorities to
undertake effective investigations of the numerous ageing bridges under their
control.
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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.
7
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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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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Bueno, Jorge García-Brioles, and Gustavo Zelmanovitz Ciulla. "Structural Optimization of Bridge Cantilever Decks : Applications of an Automated Design." Thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232735.
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Civil engineering projects involve great investments and great impacts. For that reason,engineers have a commitment with an efficient and optimal use of resources. Researchers inuniversities claim that a lot could be achieved by applying structural optimization into realprojects, even though this approach has not gained the same popularity in the industry over thelast decades.The purpose of the present thesis is to explore the possibilities offered by structural optimizationand to verify its applicability in realistic and complex structural engineering problems. Amongthe questions regarding design optimization, it was emphasized feasibility, efficiency and userfriendliness. The chosen structural system was a bridge cantilever deck. The analysis was limitedto the transversal design of the structure and the goal of the optimization was to reduce investmentcosts. In order to guarantee efficiency of the simulations, a "longitudinal length convergence"analysis was performed. It consisted of determining the minimum required longitudinal length(perpendicular to the cantilever length) that ensured reasonable accuracy. The purpose of thisanalysis was to reduce the computational time during the optimization process. In order toautomate the analysis, MATLAB was used in connection to Abaqus (to perform the FE Analysis).There were three different sets of results presented: the length convergence, application toreal projects and parametric study. In the first application, it was shown that the requiredlongitudinal length (lx) proportionally decreased as the cantilever length (lc) increased. It wasalso observed the presence of the edge beam implied in consistently larger longitudinal lengthsfor the same accuracy tolerance. With respect to the second application, two projects wereconsidered and the structural optimization presented alternatives with significant investment costreduction in a reasonable time. Furthermore, it was observed that a design solution without theedge beam reduced the costs even more. Finally, the parametric study confirmed that the costreduction obtained by eliminating the edge beam was not restricted to only certain cantileverlengths. Furthermore, it was possible to obtain the pattern of thickness variation as function ofthe cantilever length.The results of this research suggest that structural optimization could be an alternative totraditional design methods used today in consulting offices and its possibilities transcend puredesign achievements.
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Hassan, Musaab Abdalla. "Silicon carbide MEMS : characterisation and actuation of 3C-SiC cantilevers and bridges." Thesis, University of Newcastle Upon Tyne, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424338.
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Xiao, Yilin. "Analyses of reinforced concrete cantilever bridge decks under the live truck loads." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp03/MQ31659.pdf.
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Laurendeau, Matthew P. "Live-Load Testing and Finite-Element Analysis of a Steel Cantilever Deck Arched Pratt Truss Bridge for the Long-Term Bridge Performance Program." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/904.
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The Long Term Bridge Performance (LTBP) program is an organization within the Federal Highway Administration that inspects, tests, analyzes, and observes, for an extended period of time, a variety of bridge types throughout the United States. Part of the program includes periodic testing of select bridges of a span of 20 years. The Kettle River Bridge located outside of Sandstone, Minnesota was selected for study due to its unique design.
The Kettle River Bridge is a historical steel cantilevered deck arched Pratt truss bridge. The bridge was instrumented with 151 strain gauges on various floor and truss members along with eight displacement gauges strategically placed along the truss. All gauges were read simultaneously as the bridge underwent non-destructive live loading. The recorded gauge readings were analyzed to determine bridge behavior and then used in the assistance of calibrating a working finite-element model.
After a working model was verified the distribution factors for the interior and exterior floor stringers were determined. By using the controlling distribution factor, a load rating for the bridge was determined for both inventory and operating. The distribution factors and load ratings determined using the working finite-element model were then compared to the AAHSTO LRFD specifications.
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Yucel, Omer Burak. "Calibration Of The Finite Element Model Of A Long Span Cantilever Through Truss Bridge Using Artificial Neural Networks." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/3/12609850/index.pdf.
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In recent years, Artificial Neural Networks (ANN) have become widely popular tools in various disciplines of engineering, including civil engineering. In this thesis, Multi-layer perceptron with back-propagation type of network is utilized in calibration of the finite element model of a long span cantilever through truss called Commodore Barry Bridge (CBB).
The essence of calibration lies in the phenomena of comparing and correlating the structural response of an analytical model with experimental results as closely as possible. Since CBB is a very large structure having complex structural mechanisms, formulation of mathematical expressions representing the relation between dynamics of the structure and the structural parameters is very complicated. Furthermore, when the errors in the structural model and noise in the experimental data are taken into account, a calibration study becomes more tedious. At this point, ANNs are useful tools since they have the capability of learning with noisy data and ability to approximate functions.
In this study, firstly sensitivity analyses are conducted such that variations in dynamic properties of the bridge are observed with the changes in its structural parameters. In the second part, inverse relation between sensitive structural parameters and modal frequencies of CBB is approximated by training of a neural network. This successfully trained network is then fed up with experimental frequencies to acquire the as-is structural parameters and model updating is achieved accordingly.
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Čtvrtlík, Libor. "Dálniční viadukt." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2020. http://www.nusl.cz/ntk/nusl-409789.
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The aim of diploma thesis was designing motorway viaduct over rowing track. From three possible options was selected one, which represents cable stayed bridge with three spans. Design procedures and assessments were pefrormed to comply with the ultimate an serviceability limit state according to valid European standards. The calculation was performed in software Midas Civil 2020. Structural assessment was done by IDEA Statica 10.1 in combination with hand-done calculation. The part of this thesis is also enclosed drawings and visualizations.
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Retief, F. J. "An investigation into the usefulness of a method of analysis for straight, uniform-section, box-girder bridge decks with side cantilevers." Master's thesis, University of Cape Town, 1991. http://hdl.handle.net/11427/8450.
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Bibliography: leaf 110.Maisel and Ro11, in a technical report for the London Cement and Concrete Association, proposed a method of analysis, in the form of an extension of simple beam theory, which is suitable for application to straight, rectangular, single-cell, uniform-section concrete box-girder bridge-decks with side cantilevers. This method only requires a calculator for execution and if a computer is used, results for maximum stresses may be obtained almost immediately. The authors state that since their method does not discretize the structure as in the case of finite element methods, the requirements in terms of computer capacity and therefore computation time is considerably reduced. Maisel, in a later Cement and Concrete Association development report, examining the use of small computer capacity for the analysis of concrete boxbeams, indicates that the hand method was being programmed. Since the usefulness of such a method is obvious, especially if available in program form, it remains to confirm the accuracy and range of application of the method. For this purpose, four Perspex box-girder models of different depths were constructed and tested. Strain gauges were fitted at the mid- and quarter-span sections and readings for four to five loadcases per model were taken. Several problems relating to the creep and thermal properties of Perspex had to be overcome during the experimental phase. Strain values obtained from the model tests were converted to stresses and these were compared to the stresses calculated by the recommended method of analysis proposed by Maisel and Ro11. Genera lly, the exper imental results showed a very good correlation with the analytical values and thus adequately confirmed the accuracy of the method.
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Zvolánek, Lukáš. "Most přes Lochkovské údolí." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226443.
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The theme of the Master’s thesis is detailed design of superstructure for selected option of the bridge. The bridge carries highway across Lochkov valley. The superstructure, 6 spans, is made of one cell continuous box beam with large overhangs supported by prefabricated struts. The continuous beam is in plan curvature. As the first, side spans 1, 5, 6 will be casting on fixed scaffolding. Spans 2 and 4 will be casting using cantilever method, gradually hanging superstructure up. For the casting the main span will also be using cantilever method, gradually removing temporary hangers of adjacent spans. The structure was analysed according to limit states. The thesis also includes a time dependent analysis of the structure and solution of influence construction on its design.
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Šedrla, Jakub. "Most na dálnici nad Dolanským potokem." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226425.
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My thesis is focused on a design and comparism of the highway bridge across Dolansky creek. The bridge is built by balanced cantilever method. The common span length is 110metres. The bridge is post-tensioned concrete structure.The static model is made of beams.The static analysis during lifespan of bridge is made by Time discretization analysis . The design of reinforcement is made for longitudinal section and cross section.
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Emilia, Wallin. "Jämförelse av beräkningsmetoder för lastspridning i tvärled vid brobaneplattor av betong." Thesis, KTH, Betongbyggnad, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-169916.
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Denna studie har till syfte att undersöka hur lastfördelningen och följaktligen dimensionerande tvärkrafter och moment i brobaneplattor av betong skiljer sig åt beroende på val av beräkningsmetod. Jämförelsen sker primärt för tre utvalda handberäkningsmetoder som jämförts med beräkningar gjorda i ett beräkningsprogram baserat på finita elementmetoder (FEM). I jämförelsen undersöks hur laster sprids i brobaneplattan enligt de olika beräkningsmetoderna och vilka resulterande maximala snittkrafter som erhålls. Hur lastfördelningen sker är en komplex fråga och det är därför intressant att se vilka skillnader det blir i resultat utifrån olika beräkningsmetoder. Studien skedde på ett utvalt studieobjekt, en åtta meter bred samverkansbro i Njurunda strax söder om Sundsvall. De trafiklaster som beaktats är lastmodell 1 och lastmodell 2 enligt Eurokod (CEN, 2003). De beräkningsmetoder som jämförts i den här studien är dels en metod för beräkning av tvärgående konsolmoment där kantbalken bidrar mycket till den lastspridande effekten. En annan metod är för beräkning av tvärkraftsfördelning vilken generellt anses mycket gynnsam, alltså ger små tvärkrafter att dimensionera bron utifrån. Den tredje och sista handberäkningsmetoden som studerats är beräkningar av tvärgående moment i fältmitt, med hjälp av influensytediagram. Influensytediagrammen som dessa studier baseras på är framtagna av Adolf Pucher (Pucher, 1977) och kallas ibland för Pucherdiagram. Finita elementmodeller (FE-modeller) skapades för jämförelse av resultat från handberäkningar. Flera olika FE-modeller skapades med varierande detaljnivå, för att kunna se hur modelleringstekniken påverkar resultatet. I alla FE-modeller har brobaneplattan modellerats som skalelement eftersom detta är det vanligaste sättet att modellera en bro med FEM. Skillnaderna mellan de olika FE-modellerna är framför allt hur huvudbalkarna modellerats. Även ytterligare en handberäkningsmetod tillämpades för respektive snittkraft för att ge ytterligare en referens. Referensmetoderna valdes för att vara enklare metoder som baseras på andra randvillkor än de primära handberäkningsmetoderna i den här studien. Resultatet från studien visar att de förenklingar som finns i handberäkningar kan ha signifikant inverkan på resultatet. Ett konstant förhållande mellan handberäkning och FEM, där den ena beräkningsmetoden alltid resulterade i större snittkrafter, kunde inte konstateras rakt igenom studien. För tvärgående konsolmoment gav handberäkningen ett större maxmoment samt att en del skillnader kunde avläsas FE-modellerna emellan. Vid beräkning av tvärkraft gav FE-beräkningen ett resultat som var nära på det dubbla av det resultat handberäkningen gav. För Pucherdiagrammen blev resultaten varierade och det fanns ingen tydlig indikation för om handberäkningar ger större eller mindre tvärgående moment än en FE-modell. Studien resulterade bland annat i ökad kunskap om att förenklingar, vid dimensionering av en bro med hjälp av handberäkningar, kan ha stor betydelse för resultatet. Då förenklingar vid handberäkning inte går att välja av användaren finns en fördel med FEM. Fördelen med FEM är då att förenklingar styrs av användaren och det går även att studera vilken effekt en viss förenkling ger. En annan slutsats var att betong är ett material som har ett komplext beteende och i metoder som bygger på empiriska studier kan lättare få med olika effekter som finns i en verklig brobaneplatta av betong.The aim of this thesis is to study different design methods for determing load distribution, and design values for shear force and bending moment in concrete bridge decks. The study was performed based on three design methods for hand calculations, which have been compared to the results from finite element modelling (FEM). The load distribution has a major impact on the design of a bridge and how the results from different design methods will correlate is of a great interest. The evaluation has been performed on one case study, wich is an eight-meter wide composite girder bridge in Njurunda, situated south of Sundsvall in Sweden. The traffic loads applied for this study was load model 1 and load model 2 prescribed in Eurocode (CEN, 2003). One of the design methods investigated is a method used to determine for bending moment for a cantilever slab. A significant impact from the edge beam utilizes by the method to calculate the bending moment. The second method is a design method for shear forces recommended by The Swedish Transport Administration. The third and last design methods for hand calculation is to use influence charts by Pucher (Pucher, 1977). By using the influence chart to calculate the maximum bending moment in mid-span. Results from different models, created with FEM, were compared to the results from hand calculations. The bridge slab was modelled with shell elements, and the girders of the bridge were modelled in four different ways to study the impact of the level of detail in the numerical models. The results in this report show that hand calculation methods are based on significant simplifications of the structure and these may have a major impact on the results. The relation between results from hand calculation methods and results obtained with FEM was not consistent in all cases analysed. While studying the bending moment for a cantilever slab, the main conclusion was that the simplifications in the hand calculation methods resulted in significantly higher moments compared to the FE-calculations. Regarding design for shear forces, the FE analyses resulted in nearly twice as high shear forces compared to the hand calculation methods. While using the influence charts by Pucher the relation between results from hand calculations and results from FEM was not consistent. Conclusions from the study included that the simplifications in hand calculations is hard to change. These simplifications can have a major influence to the results. Some simplifications will make the results more on the safe side. With FEM the user is more free to choose which simplifications that will be made, but it can sometimes be hard to see the effect simplifications have on the results. Concrete is a complex material and design methods based on empirical studies does most likely give a result that reflects the reality better than methods based on mathematic theories.
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Smělíková, Petra. "Přemostění řeky Svitavy a tratě ČD v Blansku." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2015. http://www.nusl.cz/ntk/nusl-227189.
Full textAbstract:
The aim of the Diploma Thesis is elaboration of study of bridge crossing over the Svitava river and ČD railway track in Blansko. It concerns a five-pole steel beam road bridge with through-span which carries road of the third category. The static system of the construction is solved as solid-web beam of 1.3 meters height which is in three middle spans reinforced by truss construction with top chord and system of diagonals without verticals. The height of the main beam where reinforced by trusswork is 4.75 meters. The width of spans in the road axis is 18.5 + 30.525 + 44.4 + 30.525 + 18,5 metres. The bridge deck consists of steel cross beams bonded with reinforced concrete slab of 200 millimeters of thickness. The drive-through width of the roadway is 7.0 meters. The bridge is fitted with right-sided walkway placed on steel cantilevers. The walk-through width of the walkway is 3.0 meters. Material used is S355 Steel, C30/37 Concrete and S460 Steel which is used for marginal spans of the bridge. Load-bearing construction is assessed in compliance with current technical requirements laid down by European Directives, so called “Eurocodes”. The calculation of inner powers is performed using the Scia Engineer 2013.1 software.
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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.
Full textAbstract:
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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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.
Full textAbstract:
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.
Full textAbstract:
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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Mermigas, Konstantinos Kris. "Behaviour and Design of Extradosed Bridges." Thesis, 2008. http://hdl.handle.net/1807/17203.
Full textAbstract:
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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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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SU, CHU-YI, and 蘇哲翊. "A Study on Bride Tower Extradosed Bridge and Cantilever Bridget and Elevation Inspection." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/27430410392095974203.
Full textAbstract:
碩士中華大學
土木工程學系
105
Taiwan’s natural geographical environment is not good due to there’re many mountains, and rapid but short rivers and streams. The population is centralized at several metropolitan areas. Under these conditions, we need to build roads when encountering mountains and build bridges when meeting rivers, so as to make a complete framework for the highway system. Therefore, long-span bridges have become the common construction method in Taiwan’s bridge construction sector; among which, the Extradosed Bridge is a popular choice for many working methods. With such background, in order to make sure of the construction process and quality of this working method, this study intended to use a certain Extradosed Bridge project which located at the north section of Tai No.61 Western Coast Expressway as the research subject, and hoped to carry out the comprehensive investigation on construction’s working method, material and prestress pulling performance, so as to provide it as a basis for follow-up design and construction parameter, as well as to be used as a reference for similar constructions and follow-up engineers. This study intended to firstly investigate the Construction Automation in Taiwan’s bridge construction sector to compare the advantage and disadvantage of its working methods, as well as instruct Extradosed Bridge’s construction theory, construction procedure, the leading of external prestress till the final inspection result. In addition, the research results were focused on the inspection on the elevation points of the in-situ completed structure. Since the success and failure of such construction relied on whether the bridge deck can be reached the expected elevation when it is completed. Therefore, this study focused on these observation points that set in the construction process, as well as used the long-term construction monitoring to verify whether these original setting parameters need to be corrected or not. In fact, the prestress and pre-camber value are all theoretical inductions and calculation results, only the in-situ construction possessed many contents which may be not similar to theories, such as the elevation control points of concrete construction, the setting values of prestress parameter, and intensity of effective prestress, and that still need to make further discussion and feedback analysis. The research results proved that the segments near to the bride tower should be built by early workers, they had less familiarity and poor control of schedule; therefore, it showed a significant difference between the elevation control points and the ones originally planned. Along with the construction progress and workers’ improved familiarity, they could gradually control and focus on the precision of these points. Comparing the changes in the in-situ measured elevation on deck with the difference in calculation values, the most significant error is less than 10mm, which can be regarded as within the range of allowable error.
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Wang, Chau-Hsiang, and 王兆祥. "Stress Analysis of Cantilever Fixed Bridge." Thesis, 1996. http://ndltd.ncl.edu.tw/handle/30460319192887940097.
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Visscher, Brent Tyler. "Innovative Pre-cast Cantilever Constructed Bridge Concept." Thesis, 2008. http://hdl.handle.net/1807/11170.
Full textAbstract:
Minimum impact construction for bridge building is a growing demand in modern urban environments. Pre-cast segmental construction is one solution that offers low-impact, economical, and aesthetically pleasing bridges. The standardization of pre-cast concrete sections and segments has facilitated an improved level of economy in pre-cast construction. Through the development of high performance materials such as high strength fibre-reinforced concrete (FRC), further economy in pre-cast segmental construction may be realized. The design of pre-cast bridges using high-strength FRC and external unbonded tendons for cantilever construction may provide an economical, low-impact alternative to overpass bridge design.
This thesis investigates the feasibility and possible savings that can be realized for a single cell box girder bridge with thin concrete sections post-tensioned exclusively with external unbonded tendons in the longitudinal direction. A cantilever-constructed single cell box girder with a curtailed arrangement of external unbonded tendons is examined.
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Kuan-TsengLi and 李冠增. "Estimating Productivity of Cantilevel Constructing Bridge Activities." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/14866186313694376954.
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Wang, Chih-Hui, and 王姿慧. "Research on Bridge Engineering Falling Occupational Hazard Analysis – Cantilever Construction and Advanced Shoring Bridge Construction." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/51757154515053516605.
Full textAbstract:
碩士國立金門大學
土木與工程管理學系碩士班
101
Fall or tremble is one of the most common accidents on the bridge construction sites. Failing to effectively implement safety management and training will result in site serious occupational accidents. Current site safety management relies mostly on checklist evaluation. The evaluation results and qualities are limited by the experiences and the abilities of the evaluators, which may not achieve the goal of systematic assessment in a consistent manner. Furthermore, the current safety management and assessment methods fail to address the most critical factors to prevent incidents from their occurrences. To overcome the limitations of the traditional approach, this paper discussed the development of a fall risk assessment model for the bridge construction projects by establishing a Bayesian Network (BN) based on Fault Tree (FT) transformation. The model was proved to gain much better site safety management ability by better understanding of the probability of fall risks through the analysis of fall causes and their relationships in BN. The system has been used to analyze and verify against nine bridge construction projects currently under construction in Taiwan. It was found that the BN analysis is consistent with the conventional safety performance assessment. In practice, based upon the analysis of BN by inputting prior information about basic safety causes, the probabilities of fall risks are effectively assessed. Proper preventive safety management strategies can then be established to reduce the occurrences of fall accidents at the bridge construction projects.
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LIN, WEN-CHENG, and 林文政. "A Study on Construction Technology and Cost Benefit Analysis between Cantilever Bridge and Extradosed Bridge." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/x9q2zb.
Full textAbstract:
碩士中華大學
土木工程學系
106
The construction of new bridges in Taiwan, in view of the various terrain, geology, climate and other natural factors and the maintenance of complex transport networks in metropolitan areas, should also consider reducing the impact of natural environmental damage as well as social, economic, commercial and livelihood consequences. As a result, the design and adoption of bridges is oriented towards greater span development. At present, a large span of bridge uses the Cantilever Method more until the 2006 National Highway No. Sixth Expressway Ailan Interchange, the first introduction of Extradosed Bridge Method, the applicability of its work method and the construction principle between the cantilever bridge and the extradosed bridge was building more oblique cables and pylon. Modeling like a dinosaur spine is quite aesthetic and the domestic major projects are competing to adopt this way. As of 2018, the completed traffic and construction are more than 10 extradosed bridges. However, the introduction time of Extradosed Bridge Method is still short, and there is no experience in monitoring and the maintenance of these bridges and they are expensive. In this country financial constraints background, the public construction should take the bridge practicality as the priority, or in the bridge function, pursues the landscape, the image, the cultural and other value, but ignores the government financial predicament. In this paper, the applicability of the domestic Pre-force beam Method is used to analyze the selection of the large-span working method, and by the WH50-2 Bridge Project, the cantilever bridge and the extradosed bridge are also characterized by two kinds of working methods. On the basis of commonality and difference of construction technology, this paper analyzes the cost of direct construction quality control and management, maintenance cost after commissioning, as well as the influence degree of extradosed bridge on sightseeing benefit of Wang Gong solo area, and provides reference for future bridge design planning. The results of this paper, two kinds of working methods have the same practicability in function, and cost of the direct construction for extradosed bridge increases the costs of supervision and maintenance more than cantilever bridge.
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Chen, Ming-Huang, and 陳明煌. "Disaster Prevention for Cast-in-place Segment Cantilever of Bridge Construction." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/87018525529443625710.
Full textAbstract:
碩士國立雲林科技大學
營建工程系碩士班
95
In the recent years, Taiwan has executed construction projects for Highway No. 2, West Coast Expressway, East-West Expressway, High Speed Railway, and urban living circles. New construction methods used for the upper parts of the bridge are categorized as elevated construction. These methods may vary according to the framework, formwork, hoisting equipment and propelling equipment. If operators are not professionally trained or experienced, and there is lack of safety facilities at the work site, the operators and third parties may be exposed to danger. Based on the construction safety evaluation concept for dangerous construction work sites, this study analyzes the operational hazards and causes of construction disasters in accordance with the characteristics of cast-in-place segment cantilevers used in bridge construction and the “safety evaluation” technology applied in cantilever bridge construction. This paper takes into consideration the labor safety laws and regulations to establish disaster prevention strategies, as a reference to engineers in evaluating construction safety. The results showed that hazardous factors exist in cantilever bridge construction, from hypothesis engineering, base construction, surface construction and road and subsidiary construction. According to the disaster statistics, except for very few natural disasters, most disasters are caused by human factors, such as unsafe environment or equipment, unsafe operation or action. Therefore most disasters could be prevented. Through actual analysis and comparison of construction safety evaluation cases at dangerous work sites, and using “safety evaluation” technology in cantilever bridge construction planning, this study conducted a detailed evaluation and organized the main types of disasters. Various e strategies of disaster prevention for cast-in-place segment cantilever of bridge construction are proposed for publication. The potential hazards, preventive strategies, safety data sheet and safety evaluation procedures for cantilever construction can provide sufficient information on the hazards to contractors, allowing prevention planning, more careful construction planning, construction hazard and alternative plan evaluations to reduce occupational hazards.
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Tu, Szu-Hsien, and 杜思賢. "A case study on the productivity of Balanced Cantilever Bridge Construction." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/60633733943945510214.
Full textAbstract:
碩士國立高雄第一科技大學
營建工程所
95
There have been many studies on the aspects of safety and structure of bridges , however the issues of the bridge superstructure labor productivity were seldom mentioned and discussed. However, Thomas﹝2003﹞ pointed out that inefficient workforce management accounts for an average of almost 65% of the total inefficient work-hours, including alternate work assigned , insufficient productive work available , and overstaffing for the size of the specific construction operations . Therefore, not only the beforehand plans but the crew is also an important factor to determine weather the bridge construction will be well-done or not .This paper describes the results of one case study of cantilever bridge construction performed by four subcontractors in Jiangjyun, Tainan, Taiwan. The results first showed that disruption , the quantity of workers, and the labor productivity had bad effects on schedule . Second, inappropriate work assigned, formtraveller, and heavy equipment also had bad effects on crew productivity. These causes resulted in a loss of productivity of about 1~9％ . Third, because of the weather and inappropriate delay, it also took more time to complete the bridge, six days more. Finally, a diagram to illustrate the case-and-effect analysis of the work schedule for this project is well-developed in this study.
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Huang, Chun-Jen, and 黃俊仁. "Research on Cantilever Camber Control of High Pier Column Bridge Construction." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/f93xg3.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
105
Cantilever method is one of the proven techniques applied to bridge construction. Due to its long span on structure and high effeciency in automation, this methods owns unique advantages when construction is affected by obstacles of topography, such as spanning valleys and existing roads and railways. Therefore this method has been widely used in domestic bridge constructions today. During the condution of the cast-in-place cantilever method, camber precontrol is a big part of the construction. If two adjacent pier studs share large disparity on camber values, then they may not be joint when connecting two sides. On that occasion, they shall be connected by compulsory means, which may cause extra stress on the structure and bring risks on structure safety. Moreover, when various segments under poor controlling, a layer of AC, which will increase the self-weight, shall be added; or the exorbitant parts on completed concrete surface shall be reduced in order to meet the designated elevation. All these measures may cause damages on bridge structure and affect its persistence. Therefore, when conducitng cast-in-place cantilever method, camber precontrol is the improtant matter relating to the success of construction or not. In this study, based on the analysis of the camber development trend, we use least square method and liner regression method to make predication on the camber development trend of low pier stud. When the quality of completed bridge construction has met with accuracy requirement (with span of 1/4000), we will apply the liner regression method in construction of high pier stud to make this construction meetwith accuracy requirement as well. Based on the results, we try to prove this method can provide references to construction units on camber prediction and controlling when conducting cantilever method.
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Yu, Wu Hou, and 吳侯堉. "The Research of Bridge Failure Case by Using Unbalanced Cantilever Construction Method." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/93718100140721244506.
Full textAbstract:
碩士中華技術學院
土木防災工程研究所在職專班
97
The studied bridge is located in the eastern part of Taiwan. It was a suspension bridge which was destroyed by Typhoon. The new bridge was expected to resist wind load. Several construction methods were considered. Due to construction in the mountain, the prestressed concrete box girder unbalanced cantilever construction method was selected. Unfortunately during constructed to the tenth segment, the moveable portion was broke into two parts and fell into river. There was no one injured hopefully. This research followed the segmental construction procedure and pointed out the failure possible reasons as a reference to the later construction safety.
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Pernet, Patrick. "Replacement of incisors bonded cantilever bridge during orthodontic treatment: a case report." Master's thesis, 2021. http://hdl.handle.net/10284/10722.
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O autor apresenta um método original de substituição de dentes em falta, durante o tratamento ortodôntico, através da colagem de zircónio e estruturas cerâmicas aos dentes adjacentes ao espaço desdentado. A originalidade e interesse deste método não está tanto na ponte de cantilever colada, que já foi amplamente descrita por muitos autores, mas antes na sua utilização precoce no início do tratamento ortodôntico, em pacientes de 12-16 anos de idade, para alcançar maior conforto e sensação de bem-estar do paciente.
Esta é uma solução simples, fácil, estética e rápida: 6 meses para abrir o espaço e 10 dias para obter a ponte cantiléver.
Trata-se de um dispositivo fixo e confortável que permite ao paciente um maior conforto, do que um dispositivo removível, sem comprometer o futuro, permitindo um implante ou substituição protética posterior. O autor recorre a mais de 30 anos de experiência com cerca de 200 pacientes tratados.The author presents an original method of replacing missing teeth during orthodontic treatment by bonding zirconia and ceramic structures to the adjacent teeth of the edentulous space. The originality and interest of this method is not so much in the bonded cantilever bridge itself, which has already been extensively described by many authors, but rather in its early use at the beginning of orthodontic treatment, in patients with 12-16 years of age, to achieve greater patient comfort and feeling of wellbeing. This is a simple, easy, aesthetic, and fast solution: 6 months to open the space and 10 days to obtain the cantilever bridge. This is a comfortable, fixed device that allows the patient greater comfort than a removeable device, while not jeopardize the future, allowing for a later implant or prosthetic replacement. The author draws on more than 30 years of experience with nearly 200 patients treated.
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Chung, Sheng-Yi, and 鍾聖懿. "The Management of Pre-camber for Free Cantilever Corrugated Steel Web Bridge." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/24du77.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
106
Free cantilever corrugated steel web bridge due to steel plates substitute for concrete structure, more traditional cantilever bridge has high strength, low weight, large span, so there is significant reduction in the use of concrete or steel volume, And can meet the terrain, route requirements for a variety of bridge line design In this case, it’s the Taiwan''s first free cantilever corrugated web bridge and also the deepest free cantilever corrugated web bridge in the world. The height of the steel plate is 7.3 meters. To meet the requirements of the steel plate length, the equipment which produces corrugated steel plate was redesigned and manufactured in Taiwan. Since Taiwan regulation limitation, the corrugated steel plate and top slab form jointing method is different from the Japanese design. Because wood form site cutting precision is not good, the gap between form and corrugated steel plate is hard to overcome, resulting in leakage of cement and construction efficiency is not good. The problem had solved till the front of the steel plate with rubber and foam. The controlling and management of pre-cambers in the construction of cantilever bridges effect the future bridge shape and segmental closures. It is a very important issue during construction. If the management of pre-cambers is not properly controlled, the elevations of the cantilever-closure segments will be too large when the bridge is closed. The bridge are subjected to additional loads to achieve the purpose of closure, or make the bridge line irregular that affect the comfort of traffic. To make the traffic smooth adjust the AC paving thickness will increase the extra load on the bridge and increase the construction cost. In this study, when the upper and lower limit values of the construction monitoring difference exceeds ±25 MM, and there is no other problem, one half of the variance is regarded as the adjustment value of the following segments except the theoretical value. The prediction of camber difference is when the segment is 1/2 span, then the cantilever closure segment is predicted for the camber difference, and the variation is predicted by the regression analysis. The selected variables are the segment to column center distance and each weight of the steel plate of the segment.
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Yen, Ming-cheng, and 顏明成. "Monitoring and Assessment of Prestress Loss of Prestressed Cantilever Beam Bridge- Use Xin-Sheng Bridge as an Example." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/77239721627788723481.
Full textAbstract:
碩士逢甲大學
土木工程所
95
In order to increasing safety of bridges, the bridge monitoring systems have been established on several old bridges recently in Taiwan. In this study, the vertical deflection of the central hinge point measured from Xin-Sheng viaduct monitoring system is employed to study the long term prestress loss of prestressed concrete cantilever bridge. A SAP2000 model is constructed based on the finish draws of Xin-Sheng viaduct and the ambient vibration measurements. The CEB-FIP model is used to model the long term prestress loss due to the shrinkage and creep of concrete and the relaxation of steel tendons. The SAP2000 model is then employed to simulate the vertical deflection of the central hinge point of Xin-Sheng viaduct due to the long term prestress loss. The data of vertical deflection at the central hinge point obtained from Xin-Sheng viaduct monitoring system is then used to calibrate the needed parameters of CEB-FIP model. The SAP2000 model established in study can be used to forecast the future vertical deflection of the central hinge point, and to estimate the prestress loss of prestressed concrete cantilever bridge. On the other hand, based on the Standard Specification for Highway Bridges and the Seismic Design Specifications for Highway Bridges, the management value of monitoring instruments can be suggested.
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Cheng, Chin-Tsung, and 鄭錦聰. "A Study on Influence of Symmetric Cantilever Beam-Bridge due to Vertical Excitation." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/69917445412250071690.
Full textAbstract:
碩士國立臺灣大學
土木工程學研究所
88
This study focuses on discussing the dynamic response of symmetric cantilever beam-bridge by vertical excitation, and on finding the cantilever ratio which has the minimum value of dynamic response. First, we derive the exact solution of dynamic response of cantilever beam-bridge. Then with the model of FEM, we can calculate the dynamic response of cantilever beams with the usage of both time step analysis and spectrum analysis. Finally, we take several usual beam-spans as example, analyze their dynamic response with the before-mentioned methods, and compare their results. According to our research, the optimum ratio of the cantilever part to the central portion is between the range of 0.2 to 0.4. We hope our results will be valuable for designers who are designing cantilever beam-bridges under vertical excitation.
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weilin, Wang, and 王維麟. "The study about the Pre-camber of bridge construction — the balanced cantilever method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/86736203920664101637.
Full textAbstract:
碩士高苑科技大學
土木工程研究所
96
Pre-camber control of the cast-in-site balanced cantilever method is a very important link during the construction. If the camber is too different from the original design, the cantilever segments on both sides won’t be connected accurately. It needs exerting another force to connect coercively at the appointed time. But connecting coercively will cause extra stress and the doubt of structure safety. Whether the cast-in-site balanced cantilever method will be successful or not, Pre-camber control is the key-point. To research the tendency divination of the camber development and the identification of abnormality difference are two key-points of camber management control. The former is used to judge the difference of the camber of the two cantilevers before the construction closed up; The latter is used to find out the problems and the solution about the abnormality of arch degree. Because the live load and the work sequence of pour construction will make influence for the camber the period of the construction, it will help to assure that the stress and the alignment of the bridge finished can be satisfied with the design requirement in the future by monitoring effectively and accurately the change of the camber. In this report, the main purpose of the research on the finished alignment on girders and the camber can be satisfied with the requirement of the design. It needs making a strict management method of the camber control of bridge and a standard operation process. It can be used to control the development tendency of the camber of the girders for the trestle through structure analysis, measurement operation, identification difference, identification operation, adjustment of arch degree and feedback process accurately. The development tendency analysis of the camber for the girders adopts the least square method and uses the line linear returned method to estimate beforehand the development tendency of the camber. Then working car pushes forward, measuring the deflection influence of the former segments, to estimate the deformation difference of the former segments after pouring the concrete. Finally, make sure that the information is exact by comparing this difference with the deformation after cementing.
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Klowak, Chad. "Static & fatigue behaviour of bridge deck cantilever overhangs subjected to a concentrated load." 2007. http://hdl.handle.net/1993/20532.
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Qiu, Hui Sheng, and 丘惠生. "Long-term deflection control in a long-span segmentally constructed cantilever prestressed concrete bridge." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/24630551230247174267.
Full text
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Lon, Thou，Chin, and 饒慶龍. "The Detail Study of Post-Tensioning Concrete Box Segment Bridge Construction by Balanced Cantilever Method." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/66152409608260815192.
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Tan, Bern-Rong, and 譚本榮. "A Study of Bridge Construction using Cast-In-Site Balanced Cantilever Method With Camber Control." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/37177103286143377023.
Full textAbstract:
碩士國立高雄第一科技大學
營建工程所
95
The long span cantilever method is mainly utilized in the construction of long span bridge. The advantages of using the method include the applicability of step-by-step accomplishment of the construction, the high efficiency in the construction and the limited influence of the topographical difficulty to the construction. Therefore, this method becomes more popular and widely used in this country. It is very difficult to predict the displacement on the bridge during the long span bridge construction due to the variation with time of the properties such as its Young’s modulus, drying shrinkage, and creeping of the reinforced concrete and the physical conditions such as the relaxation of the pre-stressed steel and the loading of self-weight of the mechanical system. Therefore, it is very important to accurately control the camber during the bridge construction. In the field, it was often found that the accurate connection of the last two cantilever girders was hardly obtained in the final stage of the long span bridge construction using the cast-in-site balanced cantilever method. It is mainly caused by too much difference of the floor level between the close-up cantilever segments and the poor flatness on the cantilever girder, which was usually encountered as the leveling adjustment on the cantilever segment was not preciously accomplished. The above two problems happened were mainly because the actual level was not properly controlled to meet the design one and the immediate corresponding adjustment was not accomplished. The purpose of using the camber control method for the bridge construction using the cast-in-site balanced cantilever method is to predict the camber development on girders through the process of the data analysis, data comparison, displacement prediction and its corresponding adjustment and then provide the adjusting plan to ensure their alignment in order to satisfy the design requirements. As there are a lot of factors affecting the deviation of camber, it is crucial for a successful prediction of the camber if the most critical factor can be identified and the correct adjustment for the camber deviation can be provided immediately. The camber control can be implemented by conducting the structural analysis, data collection, displacement measurement, deviation prediction, deviation identification, identification assignment, and camber adjustment and its regression. The data utilized in this thesis was obtained from the construction site of the Guan Yue bridge, located in Route 171 of Guantian Township of Tainan County and managed by Fifth Maintenance Office of Directorate General of Highways. In this thesis, the structural analysis was completed by applying the bridge alignment and structure cross-section to the SAP 2000 solid model in order to obtain the structure behavior including the designed camber and its deviation and then comparing the analytical data with the ones obtained from the field measurement after construction. The compared result is hopefully able to provide a reference resource for the related projects in the future.
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Williams, Christopher Scott. "Strut-and-tie model design examples for bridge." Thesis, 2011. http://hdl.handle.net/2152/ETD-UT-2011-12-4661.
Full textAbstract:
Strut-and-tie modeling (STM) is a versatile, lower-bound (i.e. conservative) design method for reinforced concrete structural components. Uncertainty expressed by engineers related to the implementation of existing STM code specifications as well as a growing inventory of distressed in-service bent caps exhibiting diagonal cracking was the impetus for the Texas Department of Transportation (TxDOT) to fund research project 0-5253, D-Region Strength and Serviceability Design, and the current implementation project (5-5253-01). As part of these projects, simple, accurate STM specifications were developed. This thesis acts as a guidebook for application of the proposed specifications and is intended to clarify any remaining uncertainties associated with strut-and-tie modeling. A series of five detailed design examples feature the application of the STM specifications. A brief overview of each design example is provided below. The examples are prefaced with a review of the theoretical background and fundamental design process of STM (Chapter 2).
• Example 1: Five-Column Bent Cap of a Skewed Bridge -
This design example serves as an introduction to the application of STM. Challenges are introduced by the bridge’s skew and complicated loading pattern. A clear procedure for defining relatively complex nodal geometries is presented.
• Example 2: Cantilever Bent Cap -
A strut-and-tie model is developed to represent the flow of forces around a frame corner subjected to closing loads. The design and detailing of a curved-bar node at the outside of the frame corner is described.
• Example 3a: Inverted-T Straddle Bent Cap (Moment Frame) -
An inverted-T straddle bent cap is modeled as a component within a moment frame. Bottom-chord (ledge) loading of the inverted-T necessitates the use of local STMs to model the flow of forces through the bent cap’s cross section.
• Example 3b: Inverted-T Straddle Bent Cap (Simply Supported) -
The inverted-T bent cap of Example 3a is designed as a member that is simply supported at the columns.
• Example 4: Drilled-Shaft Footing -
Three-dimensional STMs are developed to properly model the flow of forces through a deep drilled-shaft footing. Two unique load cases are considered to familiarize the designer with the development of such models.text
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Shih, Hsues-chi, and 施學崎. "The Study of Design and Construction of Cast-in Place Cantilever Bridge Engineering Using Zu-sih Bridge Section of Nantou Living Circle Sytem." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53189876289682868432.
Full textAbstract:
碩士朝陽科技大學
營建工程系碩士班
97
In the recent years, Taiwanese government has promptly promoted infrastructural construction projects in many aspects necessary to uplift the overall competitiveness of the country. Among the major infrastructural projects, transportation networks constitute the most essential and dominant part of the constructions, especially in the major metropolitan areas where the transportation routes inevitably encounter difficult topography and man-made obstacles such as river, slope, rolling hill, existing railroad and highway,. etc.. In many cases, elevated pavement and/or bridges became necessary according to the site topography along the lines of the transportation network. The research collected and studied the important engineering elements of the commonly used bridge constructions in Taiwan and abroad, which include design concepts, construction procedures, and the characteristics, adoptability and criteria/limitation of the bridges. A selected bridge project in central Taiwan was also studied for comparison. Research was conducted with the emphasis of cast-in-place cantilever bridge which is commonly used for bridges of mid-span (35-60m) and long-span (60-120m) both in Taiwan and abroad. The contents of the study includes design concept and revealed critical automation and cycling of construction procedure for the 4 major construction types of the bridges: (1) advanced shoeing, (2) incremental launching, (3) cast-in-place cantilever, and (4) segmental advancement method. Among these, the cast-in-place cantilever which is the most used type in Taiwan, was studied to develop a list of advantage/shortcoming and improvement tactics to provide an useful guideline and reference for the deign and construction of the similar bridge construction projects in the future.
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Chang, Yun-An, and 張蘊銨. "A Finite Element Simulation for the Dynamic Analysis of Bridge Construction using Cast-in-site Balanced Cantilever Method." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/rgt63b.
Full textAbstract:
碩士國立高雄第一科技大學
營建工程所
96
ABSTRACT The dynamic analysis in the research was implemented using SAP2000 finite element program, over B2 section of the Guan Yueh bridge, located in Route 171 of Guantian Township of Tainan Country. The Guan Yueh bridge using cast-in-site balanced cantilever method has long spans. The long span cantilever method is mainly utilized in the construction of long span bridge. The advantages of using the method include the applicability of step-by-step accomplishment of the construction, the high efficiency in the construction and the limited influence of the topographical difficulty to the construction. Therefore, this method becomes more popular and widely used in this country. The long span bridge spend long time in constructing, so it in the research proceeded with the dynamic analysis of bridge construction. The Guan Yueh bridge composed of two three-span continuous beams is divided into B1 and B2. It analyzes in B2 in the research ,included the comparison of modal frequency, the abutment node displacement and stress isopleth. By analysis the result know: The construction did not tend to steady until the work finished. According to the above-mentioned phenomenon, the suggestion will that construct process in the future the can reduce time to reach the security.
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田義聖. "Discussion on Construction Alignment Control in Bridge Engineering--A Case Study for Cast-in-site Balanced Cantilever Method--." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/98208115505348163964.
Full textAbstract:
碩士國立屏東科技大學
土木工程系所
96
As the span in bridge design has been increased, and the bridge of balanced cantilever method construction alignment couldn’t well-control, such that the alignment error became uncontrolled between two adjacent cantilevers of construction section. Therefore, the situation that unable to close smoothly was happened all the time. This was come from the sections of cantilever layout level; it was not inspected effectively and changed arbitrarily during the construction phase. The purpose of this study is to apple the alignment control method through the analysis, monitor, forecasting and adjusting procedure to make sure the completion alignment of bridge will conform to the design requirement. Since the elements to influence on the alignment vary in bridge body a lot, how to forecast the camber develop correctly and find out the influence factors which effect the error for the camber are the key point in this study.
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Cheng, Chih-Hsiang, and 鄭志祥. "Automation of The Prestress Calculation in Bridge Construction Phase-A Case Study of Cast-In-Place Balanced Cantilever Construction." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/54486609135808726735.
Full textAbstract:
碩士國立臺灣科技大學
營建工程系
97
The automation in various types of construction is promoted positively in recent years, especially in the bridge construction of automation impetus. For example, Advancing Shoring Method, Incremental Launching Method and Free/Balanced Cantilever Method have already been adopted in industy for many years. Such construction techniques on automation have gradually matured. The characteristics of automation in construction methods are the standardize superstructure section, the construction equipment mechanization and the standardization of circulation construction, which is the unitization of repetitive projects. The paper develop a model to automate the prestress calculation of construction phase and based on the characteristic of the bridge construction unitization. Office VBA IDE(Interactive Development Environment) to develop a system which integrates preceding process work and rear process work of prestress analysis. Then AutoCAD 3D cartography function and AutoCAD VBA IDE are used to develop parametric bridge construction drawing and to establish the bridge 3D/VR model. The study is expected to provide a convenient and concise operation model in complicated and repeated prestress calculation work, for reducing the internal work time and improving work efficiency.
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Wong, Joe. "Analysis method for the design of reinforced concrete bridge barrier and cantilever deck under railing loads as specified in CAN/CSA-S6-00 (Canadian highway bridge design code)." Thesis, 2005. http://hdl.handle.net/2429/18996.
Full textAbstract:
The objective of this thesis is to develop a rational and effective method for designing
reinforced concrete bridge parapets and cantilevered decks so that such a method could be easily applied in practice against railing loads, as specified in the CAN/CSA-S6-00
Canadian Highway Bridge Design Code.
The maximum moment dispersal angle (MMDA) is the most promising overall of the methods being considered for this task, including yield line analysis (YLA), finite
element analysis (FEA) and the dispersal angle method. The MMDA provides a means of approximating maximum moments, which were evaluated using the linear elastic FEA at locations of interest on both the traffic barriers and the deck overhang using dispersal
angles, which are provided in the form of tables. The MMDA is an improved version of the maximum moment envelope (MME) method, which had been initially developed
based on concepts from the dispersal angle method as well as the FEA. The improved MMDA method takes advantage of the accuracy of FEA and the simplicity of the classic concept of load dispersion, while eliminating some of the issues of unconventionality
found in the dispersal angle method. Hence, MMDA is an improvement on the dispersal
angle method, as was suggested in the Commentary of S6-00. It minimizes possible
inconsistencies between the code design methods and the FEA results.
This thesis summarizes the design criteria, methods of analysis, and load applications for bridge traffic barriers and deck overhang design that has been suggested
by various jurisdictions, including AASHTO LRFD Bridge Design Specifications 2004,
Washington State DOT Bridge Design Manual LRFD, CAN/CSA-S6-88 Design of
Highway Bridges and CAN/CSA-S6-00 Canadian Highway Bridge Design Code.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Sun, Chih-Jui, and 孫枝瑞. "The Study of Labor Safety For Bridge Construction Using Cast In –Place Cantilever In Section C602 of National Highway 6." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/77472553263709958952.
Full textAbstract:
碩士朝陽科技大學
營建工程系碩士班
97
According to the results of statistical data analyses on the labor safety inspection and occupational disaster management, it is concluded that strong correlations exist between the shortcomings revealed during the inspection and injuries/casualties resulted from the occupational disasters in Taiwan in the past 5years. Very recently, the national executive administration authority has promptly promoted a “233 occupational disaster reduction program” to introduce the power of public authorities into the general occupational disaster reduction management in every aspects of the industries in Taiwan. As a result of doing so, the rate of casualty and disability due to occupational disasters has been reduced. However, due to lack of resource and knowledge related to occupational labor safety in industries in general, the improvement of the preventive/reduction programs in this regard is still far from fully accepted and adopted. In practice, a guideline for the practical applications needs to be developed and used as an essential reference to effectively reduce the losses from the occupational disasters in the future. In order to provide useful information for the purpose inspection, promotion and consultation during the field operation, the study was conducted with the focus on the hazardous factors most commonly revealed from the field inspections during the pre-cast cantilever bridge constructions in Taiwan, which includes: (1) collapse of launch wagon, (2) collapse of concrete segment, (3) falling object, (4) personnel falling, and (5) electrical shock. Improvement tactics was developed as a result of the study for the disaster reduction program depending on the revealed types of disaster and hazardous environment. The results of the study can be used by the involved professions for reduction of the disaster losses during the bridge construction operations such as construction supervisors, labor safety inspectors and related government agencies in Taiwan.