Dissertations / Theses on the topic 'Bridge vibration'
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Carroll, Seàn P. "Crowd-induced lateral bridge vibration." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/28410/.
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Vibration induced by walking pedestrians has motivated research in the civil engineering community for many years. An area within this broad field that has received particular attention is the dynamic interaction that can occur between pedestrians and laterally flexible bridge structures. Perhaps the most notable example occurring on the opening day of London's Millennium Bridge. The enduring interest in this research problem is fuelled by two of its key features; (i) the sensitivity and adaptability of human balance to lateral motion and (ii) the spatial and temporal variation in flow characteristics exhibited by a pedestrian crowd. Both of these features are addressed herein. In this project an experimental campaign was executed with the aim of identifying the interaction mechanism by which pedestrians produce force harmonics, that resonate with the oscillating structure on which they walk. These so-called self-excited forces have been experimentally identified by others but the underlying reason for their existence has remained an open question. In an effort to address this, human balance behaviour while walking on a laterally oscillating treadmill was recorded using 3-dimensional motion capture equipment. Subsequent analysis revealed that human response to sinusoidal base motion is dominated by periodic alteration of foot placement position. This produces amplitude modulation of the lateral component of the ground reaction force and is ultimately responsible for the self-excited force harmonics. It was further revealed that human centre of mass motion while walking on an oscillating structure is predominantly passive. The passive inverted pendulum model is thus an excellent model of pedestrian frontal plane balance. The second facet of this work is concerned with developing a crowd-structure interaction model that builds upon the current state of the art. The model presented utilises the understanding of human-structure interaction identified above and employs an agent-based modelling approach. Thus, the resulting 'virtual crowd' is capable of simulating key crowd features, such as inter-subject variability and emergent velocity-density flow behaviour. Using this model, it is shown that the experimentally identified human-structure interaction mechanism can lead to large amplitude lateral deck oscillations, consistent with field observations reported in the literature. The model successfully predicts the multi-mode instability of Bristol's Clifton Suspension Bridge in the absence of step frequency tuning among the crowd. This provides supporting evidence for the model's validity. The work described above has resulted in a clearer understanding of the feedback between pedestrian balance behaviour and bridge response. Furthermore, the modelling techniques developed have potential for application in the wider study of crowd-induced vibration of dynamically susceptible structures.
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Hendricks, Moghammad Sameeg. "Vibration based assessment of Kalbaskraal rail bridge." Master's thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/25285.
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The focus on the condition and performance of existing structures has increased due to the growing number of structures approaching or exceeding their design life. The challenges associated with the assessment of existing structures include deterioration, changes in loading conditions, changes in the structures function or the structure reaching the latter portion of its designed service life. In order for authorities to better determine how to deal with existing structures, there must be a coherent means of determining, measuring and benchmarking the current condition and performance of the structure. The current study proposes and demonstrates the integration of a visual based condition assessment with vibration based assessment techniques for railway bridges. The methodology suggests a systematic visual assessment combined with the development of a finite element model which is calibrated by using modal parameters ascertained from vibration based testing. The bridge which was used as a case study was the Kalbaskraal Railway Bridge located in Malmesbury. The proposed methodology consists of the following steps: 1) Initial Assessment 2) Development of a Finite Element Model 3) Detailed assessment and Ambient Vibration Field Testing 4) Analysis of Modal Parameters 5) Calibration of FEM using Modal Parameters 6) Setting up Load Configurations 7) Assessment of structural response 8) Assessment of Serviceability limit state of bridge The overall outcome of the study yielded an effective result in that the conclusions drawn from the outcomes of the methodology correlated well with previous studies on the bridge. The structure under its current operational load of 16ton/axle wagons performed within the allowable serviceability limit state. A proposed increase to 22.5ton/axle loads identified that the bridge would be performing on the boundary or above the allowable serviceability limit state and that retrofitting may have to be considered for the bridge to effectively support the additional load. The results derived from this study can be extremely valuable in the bridge management process as the information on the condition of the bridge can aid bridge authorities in their decision making processes.
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Leon, Armando. "Non-Linear Vibration and Dynamic Fracture Mechanics of Bridge Cables." Licentiate thesis, Karlskrona : Blekinge Institute of Technology, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:bth-00488.
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In the present work, the non-linear vibrations and the corresponding dynamic fracture mechanics of cables of cable-stayed bridges are studied. The cables are among the most critical components in cable-stayed bridges and there are different damage sources such as corrosion, vibration, fatigue and fretting fatigue that can significantly affect them, thereby reducing the cable’s service life and even producing their failure. Cable-Parametric Resonance is the specific non-linear vibration studied in this research. This type of vibration occurs due to displacements presented at the cable supports. These displacements are induced by the wind and traffic loads acting on the pylon and deck of the bridge. Under certain conditions, unstable cable-vibration of significant amplitude can be registered. Therefore, numerical and experimental analyses are carried out in order to describe this phenomenon and to determine the corresponding instability conditions. Two non-linear models of cable-parametric resonance are studied to predict the cable response. In the simulation method, the non-linear components are treated as external forces acting on the linear systems, which are represented by Single Degree of Freedom systems and described by digital filters. A clear non-linear relationship between the excitation and the cable response is observed in the simulations and the experiments. The corresponding experimental analysis is based on a scaled model (1:200) of the Öresund bridge and a good agreement between the numerical and experimental results is found. After obtaining the relationship between the cable response and the excitation, the cable instability conditions are determined. This is done by finding the minimum displacement required at the cable supports in order to induce nonlinear cable vibration of considerable amplitude. The instability conditions are determined within a wide range of excitation frequencies and conveniently expressed in a simplified and practical way by a curve. The determination process is rather fast and offers the possibility to evaluate all bridge cable stays in a rather short time. Finally, the dynamic fracture mechanics of the cable is considered by studying the fracture toughness characteristics of the material under dynamic conditions. Finite Element simulations on a pre-cracked three-point bending specimen under impact loading are performed. The observed cable instability is equivalently considered as the associated response to impact load conditions, and a crack as a defect on the wires of a cable stay. The simulations are based on an experimental work by using the Split Hopkinson pressure bar (Jiang et al). The dynamic stress intensity factor KI(t) up to crack initiation is then obtained by different methods. The numerical estimations based on the specimen’s crack tip opening displacement (CTOD) and mid-span displacement were closest to the experimental results. It is observed that a better estimation of the dynamic stress intensity factor relies on a proper formulation of the specimen’s stiffness.Lic March 2011
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Chang, Kuo-Wei. "Passive and Active Control of Wind Induced Bridge Vibration." Thesis, University of Nottingham, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.523132.
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Wang, Ming. "Embedded strain sensor with power scavenging from bridge vibration." College Park, Md. : University of Maryland, 2004. http://hdl.handle.net/1903/1419.
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Thesis (M.S.) -- University of Maryland, College Park, 2004.Thesis research directed by: Dept. of Civil Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Goi, Yoshinao. "Bayesian Damage Detection for Vibration Based Bridge Health Monitoring." Kyoto University, 2018. http://hdl.handle.net/2433/232013.
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Kaul, Vibhu. "Free vibration analysis of continuous orthotropic plates and bridge decks." Thesis, University of Ottawa (Canada), 1986. http://hdl.handle.net/10393/4821.
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Yang, Jing. "Theoretical and laboratory experimental studies of vehicle-excited bridge vibration." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3010743/.
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Theoretical studies of vehicle-bridge interactions have been conducted extensively, but a relatively much smaller amount of work concerns experimental studies of this problem. Full-scale tests of vehicle-bridge vibrations can be done to estimate the performance of the vehicle-bridge system or validate theoretical models, but are expensive compared with small-scale experiments in a lab. In addition, continuous bridges are paid relatively much less attention compared with simply supported bridges in the literature. This thesis is dedicated to the theoretical and the laboratory experimental studies of a four-span continuous plate structure subjected to moving cars. Firstly, the mode shapes of a multi-span continuous beam are approximated by using a number of sinusoidal functions which are the mode shapes of the beam with simply supported boundaries. The analytical solution of the continuous beam subjected to a moving force can be derived as one simple expression for the whole length of the beam based on the approximated modes, and the contributions of bridge frequencies to the modal responses of the beam would be clearly shown in the analytical solution, which can provide guidance for identifying the modal properties of the beam. This idea is illustrated by a two-span beam. The response of a simple beam subjected to a moving force is compared with that of a two-span continuous beam. The second part of this thesis is about the vehicle-bridge interaction and separation, which are investigated by using the moving sprung mass model. After that, a general approach of simulating vehicle-bridge interactions is applied to a four-span plate structure traversed by one or two moving cars at different speeds. There are two types of situations for two cars: the two cars are either separated or connected together with pitching rotation allowed for each car. The adjacent loads of two-connected-cars are almost equal distance away from each other, which is like a series of moving equidistant loads. A Laser Vibrometer is used to measure the car speeds, and four laser displacement transducers at each span are utilized to capture the structural responses. The theoretical model of the rig is updated and validated with experimental results. A frequency spectrum analysis of measured structural displacements and an in-depth parametric analysis based on the validated theoretical model are carried out.
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Feng, Yu. "Seismic evaluation of Portage Creek Bridge based on ambient vibration testing." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57919.
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Constructed in 1983, the Portage Creek Bridge is a three span highway bridge located in Victoria, British Columbia (BC), Canada. This bridge is a part of a smart seismic monitoring program, British Columbia Smart Infrastructure Monitoring System (BCSIMS), which funded by the British Columbia Ministry of Transportation and Infrastructure (MoTI), Canada. The BCSIMS aims to continuously monitor the seismic conditions of the selected bridges on lifeline highways in British Columbia, and as part of this goal, an ambient vibration test was carried out on the bridge in September 2014 in order to update/calibrate the finite element model of the bridge in SAP2000.
The updated model was then used to assess the seismic performance of the bridge in accordance with the Canadian Highway Bridge Design Code, 2015. Nonlinear time-history analysis was performed using a finite element model with concentrated plasticity, and results were compared with the performance criteria specified in the code. This thesis presents the overall procedure of the seismic evaluation, as well as the relevant theoretical background and discussion of analysis results.Applied Science, Faculty of
Civil Engineering, Department of
Graduate
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Pearson, Steven R. "On using vibration data to detect damage in model-scale reinforced concrete bridges." Thesis, University of Nottingham, 2003. http://eprints.nottingham.ac.uk/11239/.
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This thesis reports the findings of an investigation into the feasibility of using vibration characteristics to monitor the structural health of bridges. The study is the second part of a larger project commissioned by the UK Highways Agency into the investigation of possible monitoring methods that can be used in a pass/fail/monitor inspection programme. To this end, ten one-quarter-scale 5m span reinforced concrete bridge decks were fabricated and loaded incrementally to failure in the laboratory. The dynamic properties of the decks were investigated at each of the loading increments to evaluate their sensitivity to structural cracking using both free and forced vibration. The results indicated that, for the specimens tested, natural frequencies were, in general, more sensitive to the damage introduced than mode shapes. It was found that the support conditions affected the dynamic behaviour of the decks, and indeterminate boundary conditions caused significant variation in the vibration characteristics. This presented several problems in the analysis of the modal properties and, when combined with the damage introduced through static loading, caused some modes to disappear and new modes to be measured, whilst a number of modes also displayed an increase in natural frequency. The application of finite element model updating to determine reduction in flexural stiffness in the damaged areas of the deck provided a systematic method to investigate the condition of the deck. Updating was performed based on the natural frequencies of one symmetrically and one asymmetrically loaded deck, and the cracking observed under the loading, and offered results consistent with expectations. In summary, the evidence presented in this thesis suggests that the natural frequencies of the decks are, in general, more sensitive to the damage introduced than the mode shapes and consistent trends can be observed in the natural frequency change as the damage to the deck increases. However, the application of this method to indicate the structural condition of real bridges may be limited without further investigation as the vibration characteristics were affected by a number of factors arising from the realistic nature of the specimen, such as the three-dimensional distribution of the damage and the indeterminate nature of the support conditions.
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Nguyen, Dinh Tung. "Vortex-induced vibration of a 5:1 rectangular cylinder : new computational and mathematical modelling approaches." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/43008/.
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As a the limit-cycle oscillation, vortex-induced vibration (VIV) does not cause catastrophic failure but it can lead to fatigue in long and slender structures and structural elements, especially for long span bridges. Assessing this behaviour during the design stage is therefore very important to ensure the safety and serviceability of a structure. Currently, this task requires very time-consuming wind tunnel or computational simulation since a reliable mathematical model is not available. Moreover, knowledge of the underlying physical mechanism of the VIV and, particularly, of the turbulence-induced effect on the VIV is insufficient. Turbulence is normally considered to produce suppressing effects on the VIV; however, this influence appears to depend on cross sections and a comprehensive explanation is yet to be found. This issue can be resulted from some limitation that most wind tunnel or computational studies have used sectional models. The flow field is therefore dominated by 2D flow features. In this research study, the 5:1 rectangular cylinder is selected as the case study since it is considered as the generic bride deck geometry. Using the wind tunnel at the University of Nottingham, a series of wind tunnel tests using a static and elastically supported sectional model is conducted in smooth flow. This wind tunnel study is complemented by a computational study of a static and dynamic sectional model; the computational simulations are carried out using the Computational Fluid Dynamics software OpenFOAM and the High Performance Computer system at the University of Nottingham. A Fluid-structure-interaction (FSI) solver is built to model the heaving VIV. By comparing the surface pressure measurement between these two studies, it uncovers the two separate flow mechanisms and associated flow features, which are both responsible for the VIV. The series of wind tunnel static and dynamic tests is also repeated in different turbulent flow regimes. By analysing the forces, moment, surface pressure and structural response, it reveals the mechanism of the turbulence-induced effect on the aerodynamic characteristics as well as on VIV. By improving the proposed FSI solver, a novel computational approach is introduced to simulate the VIV of a flexible 5:1 rectangular cylinder excited at the first bending mode shape. Employing the Proper Orthogonal Decomposition (POD) technique and comparing against results of the sectional model, some emerging span-wise flow features are revealed together with their influences on the mechanism of the bending VIV. The Hartlen and Currie mathematical model for the VIV is generalised so that it is able to simulate the VIV response of a 3D flexible structure. Such modifications and improvements are originated from and assessed by results of the computational simulation of the flexible model. A case study of the Great Belt East bridge is then carried out to verify this modified model.
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Herron, David. "Vibration of railway bridges in the audible frequency range." Thesis, University of Southampton, 2009. https://eprints.soton.ac.uk/151141/.
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The noise level associated with a train travelling on a bridge is normally greater than that for a train travelling on plain track. It is sometimes the bridge noise that causes the highest levels of disturbance to people in the vicinity or triggers action under regulations such as the Environmental Noise Directive. Consequently, there is a need to study means of predicting noise levels from proposed bridges, noise control measures for existing structures and principles of low-noise bridge design. This thesis describes a programme of work in which an existing calculation model for bridge noise and vibration has been tested and alternative calculation methods have been developed where required. The existing model is based on analytical models for wheel-rail interaction and the calculation of the power input to the bridge. The response of the various component parts of the bridge for this power input is found using a simplified SEA scheme. In this work, the existing model has been tested against measurements made on railway bridges and the results of an advanced method of structural analysis, the Waveguide Finite Element (WFE) method. This method is well-suited to modelling some important types of railway bridge. Specifically, it allows a numerical modelling approach to be used up to higher frequency than conventional Finite Element methods. It has been found to offer some significant advantages over the existing bridge noise model, particularly for concrete-steel composite bridges and concrete box-section viaducts. The track support structure has an important influence on bridge noise and vibration, through its role in the transmission of vibration from the rail to the bridge. Laboratory measurements have been made in this work to characterise the vibration transmission properties of two important types of track support structure on bridges; ballasted track and two-stage resilient baseplate track. Improved methods of modelling the dynamic behaviour of these track forms have been developed from the measurements, which can be used in calculation models for both bridge noise and also for rolling noise.
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Oscar, Sergio Luna Vera. "Vibration-Based Performance Assessment of Prestressed Concrete Bridges." Kyoto University, 2018. http://hdl.handle.net/2433/235075.
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Ho, Man Him. "Earthquake-induced random vibration analysis of cable-stayed bridge with finite strip elements." Thesis, University of Macau, 2001. http://umaclib3.umac.mo/record=b1445038.
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Wong, Weng Heng. "Wind-induced random vibration analysis of cable-stayed bridge with finite strip elements." Thesis, University of Macau, 2000. http://umaclib3.umac.mo/record=b1636333.
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Wiberg, Niklas, and Jasmin Halilovic. "Train Induced Vibration Analysis of an End-frame Bridge : Numerical Analysis on Sidensjövägen." Thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-231911.
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Higher speeds and higher capacity will cause the Swedish rail network to be exposed to disturbing dynamic effects. Higher speeds cause higher vertical acceleration levels of the bridge deck. In this thesis, a numerical analysis of a three span end-frame bridge subjected to train induced vibrations is performed. The aim is to identify which structural components and boundary conditions that affect the dynamic behavior of the bridge. Furthermore, the influence of soil structure interaction (SSI) will be investigated as it may have contribution to the stiffness and damping of the structural system. In order to capture the dynamic response of the bridge, an analysis in the frequency domain was preformed where frequency response functions (FRF) and acceleration envelopes were obtained. For this purpose, a detailed FE-model in 3D was created. Three different cases were studied, model subjected to ballast, model subjected to soil and model subjected to both ballast and soil in coherence. A high speed load model (HSLM) was used to create simulation of train passages at different speeds and applied to all cases so that the bridge deck accelerations could be studied. A simplified 2D-model with impedance functions representing the soil-structure interaction was created to validate the results from the detailed 3D-model and for practical design purposes. The result of this numerical analysis showed that the vertical accelerations were within acceptable levels of the maximum allowed limits given in governing publications. Considering the surrounding soil, the results revealed an increase of the dynamic response in the midspan at resonant frequency. However, it was identified that this behavior is not explained by the influence of soil structure interaction but rather the change in boundary conditions of the end-shields. The same dynamic behavior was identified for the simplified 2D-model, with a slight underestimation of the vertical accelerations at resonance.
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Arvidsson, Therese. "Train–Bridge Interaction : Literature Review and Parameter Screening." Licentiate thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-144843.
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New railway lines are continuously being constructed and existing lines are upgraded. Hence, there is a need for research directed towards efficient design of the supporting structures. Increasingly advanced calculation methods can be motivated, especially in projects where huge savings can be obtained from verifying that existing structures can safely support increased axle loads and higher speeds. This thesis treats the dynamic response of bridges under freight and passenger train loads. The main focus is the idealisation of the train load and its implications for the evaluation of the vertical bridge deck acceleration. To ensure the running safety of train traffic at high speeds the European design codes set a limit on the vertical bridge deck acceleration. By considering the train–bridge interaction, that is, to model the train as rigid bodies on suspension units instead of constant moving forces, a reduction in bridge response can be obtained. The amount of reduction in bridge deck acceleration is typically between 5 and 20% for bridges with a span up to 30 m. The reduction can be higher for certain train–bridge systems and can be important also for bridge spans over 30 m. This thesis aims at clarifying for which system parameter combinations the effect of train–bridge interaction is important. To this end, a thorough literature survey has been performed on studies in train–track–bridge dynamics. The governing parameters in 2D train–bridge systems have been further studied through a parameter screening procedure. The two-level factorial methodology was applied to study the effect of parameter variations as well as the joint effect from simultaneous changes in several parameters. The effect of the choice of load model was thus set in relation to the effect of other parameter variations. The results show that resonance can arise from freight train traffic within realistic speed ranges (< 150 km/h). At these resonance peaks, the reduction in bridge response from a train–bridge interaction model can be considerable. From the screening of key parameters it can furthermore be concluded that the amount of reduction obtained with a train–bridge interaction model depends on several system parameters, both for freight and passenger train loads. In line with the European design code’s guidelines for dynamic assessment of bridges under passenger trains an additional amount of damping can be introduced as a simplified way of taking into account the reduction from train–bridge interaction. The amount of additional damping is today given as function of solely the bridge span length, which is a rough simplification. The work presented in this thesis supports the need for a refined definition of the additional damping.Nya järnvägslinjer byggs kontinuerligt och befintliga linjer uppgraderas. Det finns därför ett behov av forskning inriktad på effektiv design av de bärande konstruktionerna. Alltmer avancerade beräkningsmetoder kan vara motiverade, särskilt i projekt där stora besparingar kan erhållas från att verifiera att befintliga konstruktioner kan bära ökade axellaster och högre hastigheter. Föreliggande avhandling behandlar broars dynamiska respons under belastning av gods- och passagerartåg. Huvudfokus är att studera modelleringsalternativ för tåglasten och vilka konsekvenser de har för utvärderingen av brobanans vertikala acceleration. För att garantera trafiksäkerhet vid höga tåghastigheter definierar de europeiska normerna en maximalt tillåten vertikal acceleration i brobanan. Genom att beakta tåg-bro-interaktion, där tågkomponenterna modelleras som avfjädrade stela kroppar istället för konstanta punktlaster, kan en minskning av brons respons erhållas. Reduktionen av brobanans acceleration är typiskt mellan 5 och 20% för broar med en spännvidd på upp till 30 m. Minskningen kan vara högre för vissa tåg-brosystem och kan vara viktigt också för spännvidder över 30 m. Denna avhandling syftar till att klargöra för vilka kombinationer av tåg-broparametrar effekten av tåg-bro-interaktion är viktig. I detta syfte har en omfattande litteraturstudie genomförts inom området tåg-spår-brodynamik. De styrande parametrarna i 2D tåg-brosystem har studerats vidare i en parameterstudie. Två-nivå faktorförsök har tillämpats för att studera effekten av parametervariationer samt den ytterligare effekten av samtidiga förändringar i flera parametrar. Effekten av valet av lastmodell sattes därmed i relation till effekten av andra parametervariationer. Resultaten visar att resonans kan uppstå från godstrafik inom ett realistiskt hastighetsintervall (< 150 km/h). Vid dessa resonanstoppar kan en betydande minskning av broresponsen erhållas med en tåg-bro-interaktionsmodell. Från studien av nyckelparametrar kan man vidare dra slutsatsen att reduktionen som erhålls med en tåg-bro-interaktionsmodell beror på flera systemparametrar, både för gods- och passargerartåg. Enligt de europeiska normernas rekommendationer för dynamisk kontroll av broar för passagerartrafik kan en ökad brodämpning introduceras som ett förenklat sätt att ta hänsyn till minskningen från tåg-bro-interaktion. Mängden tilläggsdämpning anges idag som en funktion av enbart brons spännvidd, vilket är en grov förenkling. Det arbete som presenteras i denna avhandling visar på behovet av en förbättrad definition av tilläggsdämpningen.
QC 20140429
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Svedholm, Christoffer. "Efficient Modelling Techniques for Vibration Analyses of Railway Bridges." Doctoral thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-201647.
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The world-wide development of new high-speed rail lines has led to more stringent design requirements for railway bridges, mainly because high-speed trains can cause resonance in the bridge superstructure. Dynamic simulations, often utilising time-consuming finite element analysis (FEA), have become essential for avoiding such problems. Therefore, guidelines and tools to assist structural engineers in the design process are needed. Considerable effort was spent at the beginning of the project, to develop simplified models based on two-dimensional (2D) Bernoulli-Euler beam theory. First, a closed-form solution for proportionally damped multi-span beam, subjected to moving loads was derived (Paper I). The model was later used to develop design charts (Paper II) and study bridges on existing railway lines (Paper III). The model was then extended to non-proportionally damped beams (Paper IV) in order to include the effects of soil-structure interactions. Finally, the importance of the interaction between the surrounding soil and the bridge was verified by calibrating a finite element (FE) model by means of forced vibration tests of an end-frame bridge (Paper V). Recommendations on how to use the models in practical applications are discussed throughout the work. These recommendations include the effects of shear deformation, shear lag, train-bridge and soil-structure interactions, for which illustrative examples are provided. The recommendations are based on the assumption that the modes are well separated, so that the response at resonance is governed by a single mode. The results of the work show that short span bridges, often referred to as `simple´ bridges, are the most problematic with respect to dynamic effects. These systems are typically, non-proportionally damped systems that require detailed analyses to capture the `true´ behaviour. Studying this class of dynamic system showed that they tend to contain non-classical modes that are important for the structure response. For example, the bending mode is found to attain maximum damping when its undamped natural frequency is similar to that of a non-classical mode.QC 20170213
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Tavares, Rui Afonso. "Influence of the Vertical Support Stiffness on the Dynamic Behavior of High-Speed Railway Bridges." Thesis, KTH, Bro- och stålbyggnad, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-36795.
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Lorieux, Louis. "Analysis of train ‐ induced vibrations on a single ‐ span composite bridge." Thesis, KTH, Bro- och stålbyggnad, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-37021.
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Burlina, Celeste. "Aereodynamics of dry helically-filleted bridge cables." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2014. http://amslaurea.unibo.it/6744/.
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Dry limited amplitude vibrations flow-transition induced vibrations were experienced on a helically-filleted tube, in a previous study performed by Kleissl and Georgakis (2012). These vibrations have never been reported in previous studies.
A deep study on the same inclined-yawed cable configuration has been performed, in order to investigate and further understand the nature of these vibrations. The investigation has been carried out through passive-dynamic wind tunnel tests in the Climatic Wind Tunnel
at FORCE Technology, Kgs. Lyngby, Denmark.
The results are carried out in terms of aerodynamic damping and peak to peak amplitude at different flow velocities and different boundary conditions. The latter are done by testing the model with and without the spray system installed in the wind tunnel cross section, in order to
understand and evaluate the influence of the spray system on the start of the vibrations mechanism and on the flow turbulence.
The gained experiences are finally presented for the use in future testing activities with the purpose of improving the performance of passive-dynamic tests.
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Tan, Zhi Xin. "Detecting, locating and quantifying damage in slab-on-girder bridge using vibration based techniques." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/132470/1/Zhi%20Xin_Tan_Thesis.pdf.
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Bridges are designed for long life spans and the slab-on-girder bridge is one of the most commonly used bridge types in Australia and also in the world. However, changes in load characteristics, random loading, deterioration with age and environmental influences may inflict damage to the structures. This research developed a method to detect, locate and quantify damage in the slab-on-girder bridge structure at an early stage before the problem becomes visible to human eyes. Findings of this research will help to enhance the safety and efficiency of slab-on-girder bridges.
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Andersson, Andreas, and Richard Malm. "Measurement evaluation and FEM simulation of bridge dynamics." Thesis, KTH, Mechanics, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-162.
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The aim of this thesis is to analyse the effects of train induced vibrations in a steel Langer beam bridge. A case study of a bridge over the river Ljungan in Ånge has been made by analysing measurements and comparing the results with a finite element model in ABAQUS. The critical details of the bridge are the hangers that are connected to the arches and the main beams. A stabilising system has been made in order to reduce the vibrations which would lead to increased life length of the bridge.
Initially, the background to this thesis and a description of the studied bridge are presented. An introduction of the theories that has been applied is given and a description of the modelling procedure in ABAQUS is presented.
The performed measurements investigated the induced strain and accelerations in the hangers. The natural frequency, the corresponding damping coefficients and the displacement these vibrations leads to has been evaluated. The vibration-induced stresses, which could lead to fatigue, have been evaluated. The measurement was made after the existing stabilising system has been dismantled and this results in that the risk of fatigue is excessive. The results were separated into two parts: train passage and free vibrations. This shows that the free vibrations contribute more and longer life expectancy could be achieved by introducing dampers, to reduce the amplitude of the amplitude of free vibrations.
The finite element modelling is divided into four categories: general static analysis, eigenvalue analysis, dynamic analysis and detailed analysis of the turn buckle in the hangers. The deflection of the bridge and the initial stresses due to gravity load were evaluated in the static analysis. The eigenfrequencies were extracted in an eigenvalue analysis, both concerning eigenfrequencies in the hangers as well as global modes of the bridge. The main part of the finite element modelling involves the dynamic simulation of the train passing the bridge. The model shows that the longer hangers vibrate excessively during the train passage because of resonance. An analysis of a model with a stabilising system shows that the vibrations are damped in the direction along the bridge but are instead increased in the perpendicular direction. The results from the model agree with the measured data when dealing with stresses. When comparing the results concerning the displacement of the hangers, accurate filtering must be applied to obtain similar results.
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Haji, Agha Mohammad Zarbaf Seyed Ehsan. "Vibration-based Cable Tension Estimation in Cable-Stayed Bridges." University of Cincinnati / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1535636861655531.
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Gutierrez, Soto Mariantonieta. "MULTI-AGENT REPLICATOR CONTROL METHODOLOGIES FOR SUSTAINABLE VIBRATION CONTROL OF SMART BUILDING AND BRIDGE STRUCTURES." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494249419696286.
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Mohd, Raizamzamani Bin Md Zain. "Aerodynamic Instabilities of Twin Cables of Cable-stayed Bridge under Wind Actions." Kyoto University, 2018. http://hdl.handle.net/2433/235072.
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Al-Zubaidi, Jumana. "An experimental study of the vortex-induced vibration of a slender box-girder bridge deck section." Thesis, Imperial College London, 2017. http://hdl.handle.net/10044/1/59073.
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This thesis examines the vortex-induced vibration (VIV) of a very slender box-girder bridge deck section. In particular, the dependance of the response and excitation mechanism on the geometry of the bottom knuckles is investigated. This study extends previous research into VIV of bridge decks by considering a very slender box-girder with chord to depth ratio of 11.2. To the best of the author's knowledge, this study is the first to investigate experimentally the VIV of such a slender section. The behaviour of a slender box-girder in VIV was investigated experimentally, using small-scale physical modelling techniques in a wind tunnel. The excitation mechanisms are studied using pressure taps around a cross-section and several spanwise locations. Accelerometers measure the response. The findings demonstrate that the excitation mechanisms for heave and pitch responses are different (for values of wind speed, divided by frequency and chord, ≤ 1.6). The heave is excited by trailing edge vortices and shows a significant sensitivity to the geometry at the bottom knuckle. For shallow angles ≲ 20 degrees, between the base panel and the lower inclined panels, the trailing edge shedding is sufficiently weakened such that no response is observed. In contrast, the pitch response is excited by a combination of trailing edge vortices and motion-generated impinging vortices, where the frequency of shedding is double, triple and quadruple the oscillation frequency. The mode of the leading edge vortices is sensitive to the bottom knuckle angle and higher modes produce larger vibrations. A critical angle of 20 degrees results in minimum response for the bare deck (only beating angular displacement is observed) and no lock-in. The difference in excitation mechanisms for the degrees-of-freedom results in different reactions to geometrical and structural modifications, including the bottom knuckle geometry, road furniture and structural damping.
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Salami, Pargoo Navid. "Modeling and calibration of a High Speed Train Railway Bridge based on in-field vibration data." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.
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Today, high-speed trains railway bridges are monitored and analyzed more stringently and detailed to guarantee the reliability and safety of structure. The increase in speed and loads of trains can impose excessive acceleration and displacement or cause resonance in bridge superstructure, which endangers both the integrity of bridge structure and the safety of passengers using the bridge.
The thesis presents a calibration procedure for a high-fidelity finite element model of a railway bridge to identify the unknown physical parameters using operational modal data. The detailed 3D modelling can decrease the number of uncertainties in the model. The objective is to modify the influential parameters of the bridge model so that its eigenfrequencies and mode shapes matches, as closely as possible, that of the bridge under analysis. The calibration is realized by parametric analysis and manual tuning the uncertain parameters, such as support condition, to the experimental data achieved through Operational Modal Analysis. Furthermore, the optimized finite element model was utilized in moving load simulations with high-speed train loads according to the passages recorded in order to verify the model and assess the possibility of safely increasing the speed of trains travelling over the bridge.
Finally, it is shown that developing a high-fidelity finite element model may help simplifying the model calibration process for a large structure.
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Tell, Sarah. "Vibration mitigation of high-speed railway bridges : Application of fluid viscous dampers." Licentiate thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205672.
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At the moment of writing, an expansion of the Swedish railway network has started, by constructions of new lines for high-speed trains. The aim is to create a high-speed connection between the most populous cities in Sweden - Stockholm, Göteborg and Malmö, and the rest of Europe. Thereby, the likelihood of faster, longer and heavier foreign trains crossing the Swedish lines is increased. However, this could be problematic since the dynamic response in railway bridges and, consequently, the risk of resonance increases with increasing train speeds. Bridges are usually designed based on contemporary conditions and future requirements are rarely considered, due to e.g. cost issues. Prospectively, the dynamic performance of existing bridges may become insufficient. Hence, the current expansion of the high-speed railway network results in an increased demand of innovative design solutions for new bridges and cost-efficient upgrading methods for existing lines. The aim of the present thesis is to propose a vibration mitigation strategy suitable for new and existing high-speed railway bridges. The main focus is a retrofit method with fluid viscous dampers installed between the bridge superstructure and the supports, which is intended to reduce the vertical bridge deck acceleration below the European design code limits. Furthermore, the intention is to investigate the efficiency of such a system, as well as to identify and analyse the parameters and uncertainties which could influence its functionality. In order to examine the applicability of the proposed retrofit, case studies, statistical screenings and sensitivity analyses are performed and analysed. Two different models, a single-degree-of-freedom system and a finite element model, are developed and compared. From the different models, it is possible to study the influence from the damper parameters, the variability of the material properties and different modelling aspects on the bridge response. After the installation of the fluid viscous dampers, it is found that the acceleration level of the bridge deck is significantly reduced, even below the design code requirements.I skrivande stund har en utbyggnad av det svenska järnvägsnätet initierats. Målet är att skapa en höghastighetsanslutning mellan de folkrikaste städerna i Sverige - Stockholm, Göteborg och Malmö, och vidare ut i Europa. Därmed ökar sannolikheten att snabbare, längre och tyngre utländska tåg korsar de svenska järnvägslinjerna. Dock kan detta bli problematiskt i och med att järnvägsbroars dynamiska respons och, följaktligen, risken för resonans ökar med ökad tåghastighet. Broar dimensioneras ofta utifrån nuvarande förutsättningar och hänsyn tas sällan till framtida hållbarhetskrav, exempelvis p.g.a. kostnadsbesparingar. Ur ett framtidsperspektiv kan därför det dynamiska beteendet hos befintliga broar komma att bli otillräckligt. Utbyggnaden av höghastighetsnätverket ökar därmed behovet av innovativa konstruktionslösningar för nya broar och kostnadseffektiva uppgraderingsmetoder för befintliga sträckor. Syftet med föreliggande avhandling är att föreslå en metod för att minska de vibrationsnivåer som kan uppstå i både nybyggda och befintliga järnvägsbroar för höghastighetståg. Huvudfokus är en eftermonteringsmetod med viskösa dämpare, som har installerats mellan brons överbyggnad och landfästen, för att minska brobanans vertikala acceleration under gällande europeiska dimensioneringskrav. Vidare avses att undersöka effektiveteten av ett sådant system, samt att identifiera och analysera de parametrar och osäkerheter som kan påverka dess funktionalitet. Fall- och parameterstudier, samt statistiska metoder används och utvärderas för att undersöka tillämpbarheten av den föreslagna vibrationsdämpningsmetoden. Två olika modeller, ett enfrihetsgradssystem och en finit elementmodell, har skapats och jämförts. Utifrån dessa modeller kan påverkan av dämparens parametrar, variabiliteten hos materialegenskaperna och behandlingen av olika modelleringsaspekter studeras. Från resultaten är det tydligt att brobanans accelerationsnivå avsevärt reduceras efter monteringen av viskösa dämpare, till och med under dimensioneringskraven.
QC 20170425
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Barber, Matthew Gabriel. "Trends and Observations from Steel Stringer Bridge Model Calibrations." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1227027752.
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Jayasundara, Walpola Kankanamalage Nirmani. "Damage detection of arch bridges using vibration characteristics and artificial neural network." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/135524/1/Walpola%20Kankanamalage%20Nirmani_Jayasundara_Thesis.pdf.
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This project developed a method to detect, locate and quantify damage in arch bridges using variations in their vibration characteristics and artificial neural network. The method was successfully tested on a few real-life arch bridges. Outcomes of this project will contribute towards the safety of our bridges.
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Pathirage, Thisara Shamane. "Identification of prestress force in prestressed concrete box girder bridges using vibration based techniques." Thesis, Queensland University of Technology, 2017. https://eprints.qut.edu.au/112767/1/Thisara%20Shamane_Pathirage_Thesis.pdf.
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This research was aimed to develop a new vibration based non-destructive method to identify the effective prestress force in prestressed concrete box girder bridges. The research study included theoretical development, finite element analysis and laboratory testing of a scaled down box girder bridge model. A new approaches for vibration analysis of box girder bridge decks and prestress force identification were developed and tested successfully.
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Xing, Shutao. "Structural Identification and Damage Identification using Output-Only Vibration Measurements." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1067.
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This dissertation studied the structural identification and damage detection of civil engineering structures. Several issues regarding structural health monitoring were addressed.
The data-driven subspace identification algorithm was investigated for modal identification of bridges using output-only data. This algorithm was tested through a numerical truss bridge with abrupt damage as well as a real concrete highway bridge with actual measurements. Stabilization diagrams were used to analyze the identified results and determine the modal characteristics. The identification results showed that this identification method is quite effective and accurate.
The influence of temperature fluctuation on the frequencies of a highway concrete bridge was investigated using ambient vibration data over a one-year period of a highway bridge under health monitoring. The data were fitted by nonlinear and linear regression models, which were then analyzed.
The substructure identification by using an adaptive Kalman filter was investigated by applying numerical studies of a shear building, a frame structure, and a truss structure. The stiffness and damping were identified successfully from limited acceleration responses, while the abrupt damages were identified as well. Wavelet analysis was also proposed for damage detection of substructures, and was shown to be able to approximately locate such damages.
Delamination detection of concrete slabs by modal identification from the output-only data was proposed and carried out through numerical studies and experimental modal testing. It was concluded that the changes in modal characteristics can indicate the presence and severity of delamination. Finite element models of concrete decks with different delamination sizes and locations were established and proven to be reasonable.
Pounding identification can provide useful early warning information regarding the potential damage of structures. This thesis proposed to use wavelet scalograms of dynamic response to identify the occurrence of pounding. Its applications in a numerical example as well as shaking table tests of a bridge showed that the scalograms can detect the occurrence of pounding very well.
These studies are very useful for vibration-based structural health monitoring.
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Orlando, Lorenzo. "Finite Element model calibration of a historical railway steel truss bridge by using dynamic monitoring data." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022.
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This paper proposes a multidisciplinary approach, combining the terrestrial laser scanner and ambient vibration tests to characterize a historical steel truss bridge in Spain: the
Vilagarcia Celosia Bridge. All methods are complemented by advanced numerical simulations and a coarse to fine calibration strategy, based on the Cotter and the non-linear least squares approaches. Results obtained corroborate the robustness of the proposed approach, with a max error in frequencies of 3.6% and an average modal assurance criterion of 0.93.
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Shih, Hoi Wai. "Damage assessment in structures using vibration characteristics." Thesis, Queensland University of Technology, 2009. https://eprints.qut.edu.au/30319/1/Hoi_Shih_Thesis.pdf.
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Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.
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Shih, Hoi Wai. "Damage assessment in structures using vibration characteristics." Queensland University of Technology, 2009. http://eprints.qut.edu.au/30319/.
Full textAbstract:
Changes in load characteristics, deterioration with age, environmental influences and random actions may cause local or global damage in structures, especially in bridges, which are designed for long life spans. Continuous health monitoring of structures will enable the early identification of distress and allow appropriate retrofitting in order to avoid failure or collapse of the structures. In recent times, structural health monitoring (SHM) has attracted much attention in both research and development. Local and global methods of damage assessment using the monitored information are an integral part of SHM techniques. In the local case, the assessment of the state of a structure is done either by direct visual inspection or using experimental techniques such as acoustic emission, ultrasonic, magnetic particle inspection, radiography and eddy current. A characteristic of all these techniques is that their application requires a prior localization of the damaged zones. The limitations of the local methodologies can be overcome by using vibration-based methods, which give a global damage assessment. The vibration-based damage detection methods use measured changes in dynamic characteristics to evaluate changes in physical properties that may indicate structural damage or degradation. The basic idea is that modal parameters (notably frequencies, mode shapes, and modal damping) are functions of the physical properties of the structure (mass, damping, and stiffness). Changes in the physical properties will therefore cause changes in the modal properties. Any reduction in structural stiffness and increase in damping in the structure may indicate structural damage. This research uses the variations in vibration parameters to develop a multi-criteria method for damage assessment. It incorporates the changes in natural frequencies, modal flexibility and modal strain energy to locate damage in the main load bearing elements in bridge structures such as beams, slabs and trusses and simple bridges involving these elements. Dynamic computer simulation techniques are used to develop and apply the multi-criteria procedure under different damage scenarios. The effectiveness of the procedure is demonstrated through numerical examples. Results show that the proposed method incorporating modal flexibility and modal strain energy changes is competent in damage assessment in the structures treated herein.
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Acar, Yalda, and Pontus Jingstål. "Influence of the Non-linear Effects in the Design of Viscous Dampers for Bridge Cables." Thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-153956.
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In this master thesis the performance of external viscous dampers attached to cables in cable-stayed bridges have been studied. A comparison has been performed between a linear and a non-linear cable model. The comparison was carried out for two bridge cables, one from the Dubrovnik Bridge and the other from the Normandie Bridge. The performance of the dampers have been measured in terms of maximum achieved damping ratio and minimum amplitude of vibration. The analysis was performed using the finite element method. The damping ratio was measured using both the half-power bandwidth method and by calculating the loss factor. The half-power bandwidth method can only be applied to a linear system. Therefore, the loss factor was evaluated for the linear model and compared to the results obtained using the half-power bandwidth method. From the comparison, it was concluded that the damping ratio evaluated using the loss factor was similar to the results obtained when using the half-power bandwidth method. However, when calculating the loss factor, it was of great importance that the resonance frequency of the system was accurately determined. The loss factor was then calculated for the non-linear model and compared to the results obtained for the linear model. Since the loss factor measures the energy dissipated in a system, it could be utilised for the non-linear model. When computing the strain energy for the non-linear model an approximate method was used to take into consideration the strain energy caused by the static deformation of the cable. From the comparison between the linear and non-linear cable models, it was concluded that the optimal damper coefficients obtained by both models are not significantly different. However, there is an uncertainty in the results due to the fact that an approximate method was used when calculating the strain energy for the nonlinear model. It was also observed that a very accurate evaluation of the system’s resonance frequency was needed to calculate the loss factor. It was also observed that the variation in amplitude of vibration for varying damper coefficient was small for all modes of vibration for the Dubrovnik Bridge Cable as well as for the first mode of vibration for the Normandie Bridge Cable. The difference in the results between the two bridge cables needs to be investigated further in order to get a better understanding of the results.
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Ramos, Pablo D. Jr. "SYSTEM IDENTIFICATION OF A BRIDGE-TYPE BUILDING STRUCTURE." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/944.
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The Bridge House is a steel building structure located in Poly Canyon, a rural area inside the campus of California Polytechnic State University, San Luis Obispo. The Bridge House is a one story steel structure supported on 4 concrete piers with a lateral force resisting system (LFRS) composed of ordinary moment frames in the N-S direction and braced frames in the E-W direction and vertically supported by a pair of trusses. The dynamic response of the Bridge House was investigated by means of system identification through ambient and forced vibration testing. Interesting findings such as diaphragm flexibility, foundation flexibility and frequency shifts due to thermal effects were all found throughout the mode shape mapping process. Nine apparent mode shapes were experimentally identified, N-S and E-W translational, rotational and 6 vertical modes. A computational model was also created and refined through correlation with the modal parameters obtained through FVTs. When compared to the experimental results, the computational model estimated the experimentally determined building period within 8% and 10% for both N-S and E-W translational modes and within 10% for 4 of the vertical modes.
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Moradi, Pour Parviz. "An improved modal strain energy method for bridge damage identification." Thesis, Queensland University of Technology, 2020. https://eprints.qut.edu.au/201001/1/Parviz_Moradi%20Pour_Thesis.pdf.
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This thesis improved a modal strain energy (MSE) based damage detection method to detect the damage in bridges. Firstly, an elemental MSE and a sensitivity matrix were mathematically established. Then, it was numerically and experimentally tested on some models such as a fixed-end beam, a three-story frame, the 4-DOF three-story structure of Los Alamos National Laboratory and the I-40 Bridge in New Mexico as a real bridge. The results showed the capability of the proposed method. The research findings will contribute to academic studies and bridge industry to minimize the loss of lives and property by identifying the structural damages.
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Wang, Xiaoqi, and Shufan Ye. "A pre-study of the dynamic behavior of a single diagonal timber arch bridge." Thesis, KTH, Byggnadsmaterial, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-292580.
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The aim of this Master’s thesis was to study the dynamic behaviour of a special type ofpedestrian timber bridge with a single diagonal arch - a design proposal made in a previousstudent project. The bridge is intended to be built as a gateway to the Alfred Nobel’s Björkbornin the municipality of Karlskoga. The original plan for this thesis was to build and test adownscaled model in order to verify theoretical investigations. The laboratory testing washowever not possible to be performed, therefore the study was conducted only by means ofanalytical and numerical tools. Both a downscaled model and a full-scale bridge model wereanalysed and compared in order to find proper scale parameters. Different studies wereperformed on the models by means of the finite element method in order to investigate theinfluence of relevant parameters on dynamic behaviour of the bridge. A scale factor wasdetermined which allows for the translation of results from the downscaled model to the fullscale model. Results showed that the dynamic behaviour of this type of bridge is rathercomplicated, and the original design needs to be somewhat modified to meet the comfortcriterion for pedestrians. An increase of the width of the arch, a proper arrangement of thecables, and adoption of longitudinal steel beams under the deck were found to be efficientmethods to improve the dynamic performance of the bridge. Future work should includeexperiments on a downscaled model to validate these theoretical solutions.
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Widjaja, Matius Andy. "The Influence of the Recommended LRFD Guidelines for the Seismic Design of Highway Bridges on Virginia Bridges." Thesis, Virginia Tech, 2003. http://hdl.handle.net/10919/31453.
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The influence of the recommended LRFD Guidelines for the seismic design of highway bridges in Virginia was investigated by analyzing two existing bridges. The first bridge has prestressed concrete girders and is located in the Richmond area. The second bridge has steel girders and is located in the Bristol area. The analysis procedure for both bridges is similar. First the material and section properties were calculated. Then the bridge was modeled in RISA 3D. Live and dead load were imposed on the bridge to calculate the cracked section properties of the bridge. The period of vibration of the bridge was also calculated. After the soil class of the bridge was determined, the design response spectrum curve of the bridge was drawn. The spectral acceleration obtained from the design spectrum curve was used to calculate the equivalent earthquake loads, which were applied to the superstructure of the bridge to obtain the earthquake load effects. Live and dead loads were also applied to get the live and dead load effects. The combined effects of the dead, live and earthquake loads were compared to the interaction diagram of the columns and moment strength of the columns. The details of the bridge design were also checked with the corresponding seismic design requirement.A parametric study was performed to explore the effects of different column heights and superstructure heights in different parts of Virginia. The column longitudinal reinforcing was increased to satisfy the bridge axial loads and moments that are not within the column interaction diagram.Master of Science
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Naderian, Hamidreza. "Advanced Numerical Techniques for Dynamic and Aerodynamic Analysis of Bridges." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/36089.
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To meet the economic, social and infrastructure needs of the community for safe and efficient transportation systems, long span bridges have been built throughout the world. Long span bridges are one of the most challenging kinds of structures in civil engineering. The cable-stayed bridges are of great interest mainly as an alternative and a more economic solution than the one of suspension bridges. In addition, the fiber reinforced polymer (FRP) composites are, nowadays, successfully used for constructing modern bridges, where the significant weight saving provides additional benefits. Because of the great flexibility, modern long-span cable-stayed bridges are usually very susceptible to dynamic loads especially to the earthquake and strong winds. Therefore, the earthquake-resistant and wind-resistant designs become one of key issues for successful construction of bridges.
The objective of the present research is to develop a very efficient spline finite strip technique, for modelling and analysis of both conventional and hybrid FRP cable-stayed bridges. The study falls into the categories of bending, free vibration, seismic, and aerodynamic flutter analysis. The spline finite strip method (SFSM) is one of the most efficient numerical methods for structural analysis of bridges, reducing the time required for estimating the structural response without affecting the degree of accuracy. In the finite strip method, the degrees of freedom could be significantly reduced due to the semi-analytical nature of this method. However, the previous versions of SFSM are not able to model the entire bridge system. For that reason, the structural interactions between different structural components of the bridge could not be handled. In addition, the vibrations and displacements of the towers and cables could not be investigated. In the present formulation, all these obstacles have been eliminated. Moreover, the proposed finite strip technique is very efficient and accurate due to the drastic reduction in the formulation time, simplicity of data preparation, rapid rate convergence of the results, and the semi-analytical nature.
Last but not least, and for the first time, a fully finite strip solution is extended to the area of wind engineering. Using the spline finite strip discretization, the aerodynamic stiffness and mass properties of the long-span cable-stayed bridge are derived. The aerodynamic properties along with the structural properties of long-span plates and bridges are formulated in the aerodynamic equation of motion and are used to analyze the flutter problem.
The accuracy and efficiency of the proposed advanced finite strip method is verified against the finite element and field measurement results. The results demonstrate that this methodology and the associated computer code can accurately predict the dynamic and aerodynamic responses of the conventional and FRP long-span cable-stayed bridge systems. The outcome of the present research will lead to a comprehensive structural analysis of bridges in the framework of the proposed discretization which is more efficient and straightforward than the finite element analysis.
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Cowled, Craig J. "On the influence of structural complexity on the global vibration characteristics of steel truss bridges." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/115793/1/Craig_Cowled_Thesis.pdf.
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This research focuses on the vibration characteristics of steel truss bridges and how structural complexity influences the chances of successful damage detection (DD). The structural complexity of almost 200 structures from the literature is quantified, highlighting that DD is less successful for experimental structures with high levels of complexity as compared to structures with low levels of complexity. The vibration characteristics of a complex structure were studied under different damage scenarios, revealing that the characteristics most sensitive to damage were also the characteristics with the highest variance. In short, structural complexity makes damage detection difficult.
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Senturk, Tolga. "Impact Of Passanger Comfort Level On Design Of Short-span Composite Steel I-girder High Speed Railroad Bridges." Master's thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/3/12611320/index.pdf.
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In globalizing world, increase in demand for high speed rail travel requires comfortable ride over bridges while maintaining an economical design. These bridges either have composite steel I-girders, prestressed precast I or box girder superstructures. The span lengths can reach up to 40 meters. If frequency of wheel load pass at a point on bridge matches with one the critical frequencies of the structure, excessive vibration can developed both at the train and the bridge even if the structure is structurally safe. Excessive vibration can discomfort the passengers. Focus of this study is given to identify certain thresholds for the rigidity of span to minimize the passenger discomfort at short-span composite steel I-girder high speed railroad bridges. In this context, various span lengths with different girder configurations have been analyzed under various train design speeds and ballast stiffness. Eigenvalue analyses are performed to determine critical frequencies of bridges. Moving force models are used to determine structural vibrations as recommended by high speed railroad bridge design specifications. It is well-known that stiffer structures can have significantly less vibration amplitudes than lighter ones providing a comfortable ride for high speed train passes.
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Murugesan, Kaviraj. "Damage detection on railway bridges using system identification." Thesis, Karlstads universitet, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-28595.
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Vallis, Matthew Bruce. "Investigação experimental em túnel de vento dos efeitos causados por dispositivos aerodinâmicos na resposta de tabuleiros de ponte frente ao desprendimento de vórtices." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2013. http://hdl.handle.net/10183/156819.
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“Estas vibrações são as primeiras do seu tipo para as pontes tipo viga….elas mostram a alta estabilidade aerodinâmica e confiabilidade da estrutura" (Anishyuk e Antonova, 2010). Esta é uma citação do porta-voz da empresa responsável pela construção da ponte, com vãos 120m e de 7 km de extensão, em Volgograd, na Rússia – que oscilou tão violentamente sob velocidades baixas do vento em maio de 2010, que os motoristas ficaram enjoados e a ponte foi fechada. As filmagens do movimento da ponte podem ser encontradas facilmente na internet, e causam uma visão perturbadora. O que é mais perturbador é que a empresa responsável pelo seu projeto e construção pôde ser tão ignorante da história das aerodinâmicas de pontes e conceitos aerodinâmicos básicos.As vibrações induzidas por vórtices que tinham atormentadas a Ponte Volgograd são agora atenuadas por um sistema avançado de dispositivos de amortecimento mecânico. Se as medidas de segurança tivessem sido tomadas durante a fase do projeto, a necessidade desses dispositivos de amortecimento poderia ter sido evitada. Uma variedade de dispositivos aerodinâmicos passivos tem apresentado ser extremamente eficaz na supressão das vibrações induzidas por vórtices em velocidades baixas do vento para um número de pontes de grande vão Investigações adequadas em túnel de vento realizadas durante a fase do projeto podem alertar os projetistas da existência de instabilidades aerodinâmicas inerente no projeto, e passos podem ser tomados para modificar o formato do tabuleiro para otimizar o seu desempenho dinâmico sob cargas de vento. Investigações experimentais da efetividade na supressão das vibrações induzidas por vórtices, por uma série de dispositivos aerodinâmicos passivos, têm sido realizadas no Túnel de Vento Prof. Joaquim Blessmann, em Porto Alegre. Dispositivos foram projetados com base nas modificações feitas a outros projetos de pontes que sofreram com as vibrações indesejadas da velocidade baixa do vento, tanto no túnel de vento durante a fase do projeto, durante a construção ou após a conclusão da ponte em grande escala. Dispositivos foram testados usando um modelo dinâmico de uma ponte da vida real, e os resultados indicaram que algumas modificações simples a geometria da seção transversal do tabuleiro podem ter um efeito significativo na sua resposta.“These vibrations are the first of their kind for beam-type bridges….they show the high aerodynamic stability and reliability of the structure” (Anishyuk and Antonova, 2010). This is a quote taken from the spokesman of the company responsible for the construction of the 7km long reinforced concrete bridge in Volgograd, Russia – whose multiple continuous 120 meter spans oscillated so violently under low-wind speed conditions in May of 2010 that motorists became seasick and the bridge was closed. Footage of the bridge’s movement can easily be found on the internet, and makes for disturbing viewing. What is even more disturbing is that the company responsible for its design and construction could be so ignorant to the history of bridge aerodynamics and basic aerodynamic concepts. The vortex-induced vibrations which had plagued the Volgograd Bridge are now mitigated by an advanced system of mechanical damping devices. If proper precautions had been taken during the design stage of the bridge, the necessity of these damping devices could have been avoided. A variety of passive aerodynamic devices have been shown to be extremely effective in the suppression of low wind speed vortex-induced vibrations for a number of long-span bridges Proper wind-tunnel investigations undertaken during the design stage can alert designers to the existence of aerodynamic instabilities inherent to the design, and steps can be taken to modify the shape of the deck to optimise its dynamic performance under wind loads. Experimental investigations of the effectiveness of range of passive aerodynamic devices to suppress vortex-induced vibrations have been conducted at the Professor Joaquim Blessmann Wind-Tunnel, Porto Alegre. Devices were designed based on modifications made to other bridge designs which suffered from unwanted low wind speed vibrations, either in the windtunnel during the design stage, during erection or after completion of the full-scale bridge. Devices were tested using a dynamic section model of a real-life bridge deck design. Results indicate that some simple modifications to the cross-section geometry of the deck can have a substantial effect on its response.
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Zäll, Emma. "Footbridge Dynamics : Human-Structure Interaction." Licentiate thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-224527.
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For aesthetic reasons and due to an increased demand for cost-effective and environmentally friendly civil engineering structures, there is a trend in designing light and slender structures. Consequently, many modern footbridges are susceptible to excessive vibrations caused by human-induced loads. To counteract this, today's design guidelines for footbridges generally require verification of the comfort criteria for footbridges with natural frequencies in the range of pedestrian step frequencies. To ensure that a certain acceleration limit is not exceeded, the guidelines provide simplified methodologies for vibration serviceability assessment. However, shortcomings of these methodologies have been identified. First, for certain footbridges, human-structure interaction (HSI) effects might have a significant impact on the dynamic response. One such effect is that the modal properties of the bridge change in the presence of a crowd; most importantly, the damping of the bridge is increased. If this effect is neglected, predicted acceleration levels might be overestimated. Second, as a running person induces a force of greater amplitude than a walking person, a single runner might cause a footbridge to vibrate excessively. Hence, the running load case is highly relevant. These two aspects have in common that they are disregarded in existing design guidelines. For the stated reasons, the demand for improvements of the guidelines is currently high and, prospectively, it might be necessary to require the consideration of both the HSI effect and running loads. Therefore, this licentiate thesis aims at deepening the understanding of these subjects, with the main focus being placed on the HSI effect and, more precisely, on how it can be accounted for in an efficient way. A numerical investigation of the HSI effect and its impact on the vertical acceleration response of a footbridge was performed. The results show that the HSI effect reduces the peak acceleration and that the greatest reduction is obtained for a crowd to bridge frequency ratio close to unity and a high crowd to bridge mass ratio. Furthermore, the performance of two simplified modelling approaches for consideration of the HSI effect was evaluated. Both simplified models can be easily implemented and proved the ability to predict the change in modal properties as well as the structural response of the bridge. Besides that, the computational cost was reduced, compared to more advanced models. Moreover, a case study comprising field tests and simulations was performed to investigate the effect of runners on footbridges. The acceleration limit given in the design guideline was exceeded for one single person running across the bridge while a group of seven people walking across the bridge did not cause exceedance of the limit. Hence, it was concluded that running loads require consideration in the design of a footbridge.På grund av estetiska skäl och en ökad efterfrågan på kostnadseffektiva och miljövänliga konstruktioner är merparten av de gångbroar som konstrueras idag förhållandevis lätta och slanka. Med anledning av detta ökar risken för att stora svängningar uppstår på grund av dynamisk belastning från människor på bron. För att motverka att detta inträffar kräver dagens normer att komforten verifieras för gångbroar med egenfrekvenser inom området för människans stegfrekvens. Komforten verifieras genom att säkerställa att ett visst accelerationskriterium inte överskrids. För detta ändamål finns handböcker som tillhandahåller förenklade beräkningsmetoder för uppskattning av accelerationsnivåer. Brister i dessa beräkningsmetoder har emellertid identifierats. För det första kan olika typer av människa-bro-interaktion (HSI) ha en betydande inverkan på responsen hos vissa broar. Exempel på en HSI-effekt är att brons modala egenskaper förändras när människor befinner sig på bron; i huvudsak sker en ökning av brons dämpning. Om denna effekt inte tas i beaktande föreligger stor risk att överskatta förväntade accelerationsnivåer. För det andra är kraften från en löpare större än kraften från en gående person vilket gör att en ensam löpare på en gångbro kan ge upphov till accelerationsnivåer som överskrider gränsvärdena för komfort. Löpande personer är därför ett mycket relevant lastfall. Befintliga normer uttrycker inte explicit att någon av dessa aspekter bör tas i beaktande. Behovet av förbättrade riktlinjer för hur normerna bör tillämpas är därför mycket stort och i framtiden kan det bli nödvändigt att kräva att både HSI-effekter och löparlaster tas i beaktande. Därför syftar denna licentiatavhandling till att bidra till en fördjupad förståelse inom dessa två ämnen, med huvudfokus på ovan nämnda HSI-effekt i allmänhet och hur den kan beaktas på ett enkelt, noggrant och tidseffektivt sätt i synnerhet. En numerisk undersökning av HSI-effekten och dess inverkan på den vertikala responsen hos en gångbro genomfördes. Resultaten visar att HSI-effekten reducerar den maximala accelerationen och att störst reduktion erhålls då folksamlingen och bron har ungefär samma egenfrekvens och då folksamlingens massa är stor i förhållande till brons massa. Vidare utvärderades två förenklade metoder för beaktande av HSI-effekten vilka kan implementeras av konstruktörer med grundläggande kunskaper inom strukturdynamik. Det konstaterades att båda metoderna uppskattar HSI-effekten såväl som brons respons förhållandevis väl samtidigt som de reducerar beräkningstiden något jämfört med mer avancerade metoder. Effekten av löpare på gångbroar studerades genom en fallstudie med fältmätningar. Utifrån resultaten från dessa fältmätningar kunde det konstateras att accelerationsgränsen som anges i normerna överskreds när en ensam löpare sprang över bron men inte när en grupp på sju personer gick i takt över samma bro. Därför drogs slutsatsen att löparlaster bör tas i beaktande vid dimensionering av en gångbro.
QC 20180320
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Pebley, Aaron James. "Bending stresses in stay-cables during large-amplitude vibrations a Fred Hartman Bridge case study /." Full-text Adobe Acrobat (PDF) file, 2005. http://www.engr.utexas.edu/research/fsel/FSEL_reports/Thesis/Pebley,%20Aaron.pdf.
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Guan, Hong. "Vibration-based structural health monitoring of highway bridges." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC IP addresses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211821.
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Rehmanjee, Yasmin H. (Yasmin Hydery) 1976. "Lateral vibration of pedestrian bridges." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/84286.
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Thesis (M.Eng.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2001."June 2001."
Includes bibliographical references (leaf 56).
by Yasmin H. Rehmanjee.
M.Eng.