To see the other types of publications on this topic, follow the link: Structural damage to bridges.
Dissertations / Theses on the topic 'Structural damage to bridges'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Structural damage to bridges.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Neild, S. A. "Using non-linear vibration techniques to detect damage in concrete bridges." Thesis, University of Oxford, 2001. http://ora.ox.ac.uk/objects/uuid:f116c6f1-3179-463b-9ff6-b83e48a71aaf.
Full textAbstract:
There has been much work published in recent years on the use of vibration characteristics to detect damage in bridges. Almost all of this work has been based on the assumption that the vibration is linear, i.e. the natural frequencies are not dependent on the amplitude of oscillation. The aim of the work presented here was to investigate the possibility of using changes in the non-linear vibration characteristics to detect damage in reinforced concrete bridges. These changes in the non-linear vibration characteristics were studied by conducting impact excitation vibration tests o reinforced concrete beams. The non-linearities were detected by examining the changes in fundamental frequency over time (and hence over amplitude of vibration). Several time-frequency distribution estimation tools are discussed including the discrete Fourier Transform moving window, the auto-regressive model moving window, harmonic wavelets and examples of the Cohen class of bilinear time-frequency distributions. A detailed investigation into these various distribution predictors was conducted to assess which is most suitable for analysing the vibration signals to detect changes in frequency with time. To understand the non-linearities in the vibration characteristics, a time-stepping model was described. The model is capable of including damage in the form of a moment-rotation relationship over the cracked region. It was validated for linear vibrations against theoretical values and the representation of a non-linear mechanism using the model was compared with experimental data. Static load tests were also conducted on the beams at various damage levels. They involved the use of vibrating wire strain gauges to investigate the moment-rotation behaviour over the cracked region. Several possible non-linear crack mechanisms are discussed and two of them are assessed using the vibration and the static load tests. Future experimental work is proposed to study the possible non-linear mechanisms further. The beam tests demonstrated that there is a change in non-linear vibration behaviour with damage. The change is greatest at low levels of damage and after the beam has been loaded to 30% of the failure load in three-point loading there is a reversal in the trend and a slight reduction in non-linearity with further damage.
2
Neves, Cláudia. "Structural Health Monitoring of Bridges : Model-free damage detection method using Machine Learning." Licentiate thesis, KTH, Bro- och stålbyggnad, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-205616.
Full textAbstract:
This is probably the most appropriate time for the development of robust and reliable structural damage detection systems as aging civil engineering structures, such as bridges, are being used past their life expectancy and beyond their original design loads. Often, when a significant damage to the structure is discovered, the deterioration has already progressed far and required repair is substantial. This is both expensive and has negative impact on the environment and traffic during replacement. For the exposed reasons the demand for efficient Structural Health Monitoring techniques is currently extremely high. This licentiate thesis presents a two-stage model-free damage detection approach based on Machine Learning. The method is applied to data gathered in a numerical experiment using a three-dimensional finite element model of a railway bridge. The initial step in this study consists in collecting the structural dynamic response that is simulated during the passage of a train, considering the bridge in both healthy and damaged conditions. The first stage of the proposed algorithm consists in the design and unsupervised training of Artificial Neural Networks that, provided with input composed of measured accelerations in previous instants, are capable of predicting future output acceleration. In the second stage the prediction errors are used to fit a Gaussian Process that enables to perform a statistical analysis of the distribution of errors. Subsequently, the concept of Damage Index is introduced and the probabilities associated with false diagnosis are studied. Following the former steps Receiver Operating Characteristic curves are generated and the threshold of the detection system can be adjusted according to the trade-off between errors. Lastly, using the Bayes’ Theorem, a simplified method for the calculation of the expected cost of the strategy is proposed and exemplified.QC 20170420
3
Brown, Graham. "A study of the effect of damage on the dynamic response of masonry arch bridges." Thesis, University of Reading, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.246045.
Full text
4
Gonzalez, Ignacio. "Application of monitoring to dynamic characterization and damage detection in bridges." Doctoral thesis, KTH, Bro- och stålbyggnad, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150804.
Full textAbstract:
The field of bridge monitoring is one of rapid development. Advances in sensor technologies, in data communication and processing algorithms all affect the possibilities of Structural Monitoring in Bridges. Bridges are a very critical part of a country’s infrastructure, they are expensive to build and maintain, and many uncertainties surround important factors determining their serviceability and deterioration state. As such, bridges are good candidates for monitoring. Monitoring can extend the service life and avoid or postpone replacement, repair or strengthening works. The amount of resources saved, both to the owner and the users, by reducing the amount of non-operational time can easily justify the extra investment in monitoring. This thesis consists of an extended summary and five appended papers. The thesis presents advances in sensor technology, damage identification algorithms, Bridge Weigh-In-Motion systems, and other techniques used in bridge monitoring. Four case studies are presented. In the first paper, a fully operational Bridge Weigh-In-Motion system is developed and deployed in a steel railway bridge. The gathered data was studied to obtain a characterization of the site specific traffic. In the second paper, the seasonal variability of a ballasted railway bridge is studied and characterized in its natural variability. In the third, the non-linear characteristic of a ballasted railway bridge is studied and described stochastically. In the fourth, a novel damage detection algorithm based in Bridge Weigh-In-Motion data and machine learning algorithms is presented and tested on a numerical experiment. In the fifth, a bridge and traffic monitoring system is implemented in a suspension bridge to study the cause of unexpected wear in the bridge bearings. Some of the major scientific contributions of this work are: 1) the development of a B-WIM for railway traffic capable of estimating the load on individual axles; 2) the characterization of in-situ measured railway traffic in Stockholm, with axle weights and train configuration; 3) the quantification of a hitherto unreported environmental behaviour in ballasted bridges and possible mechanisms for its explanation (this behaviour was shown to be of great importance for monitoring of bridges located in colder climate) 4) the statistical quantification of the nonlinearities of a railway bridge and its yearly variations and 5) the integration of B-WIM data into damage detection techniques.QC 20140910
5
Li, Zhe. "Soft computing for damage prediction and cause identification in civil infrastructure systems." Diss., Connect to online resource - MSU authorized users, 2008.
Find full textAbstract:
Thesis (Ph.D.)--Michigan State University. Dept. of Civil and Environmental Engineering, 2008.Title from PDF t.p. (viewed on July 21, 2009) Includes bibliographical references (p. 218-225). Also issued in print.
6
Kapitan, Jacob G. "Structural assessment of bridge piers with damage similar to alkali silica reaction and/or delayed ettringite formation." Full-text Adobe Acrobat (PDF) file, 2006. http://www.engr.utexas.edu/research/fsel/FSEL_reports/Thesis/Kapitan,%20Jacob.pdf.
Full text
7
Bayissa, Wirtu Lemessa. "Damage identification and condition assessment of civil engineering structures through response measurement /." Connect to thesis, 2007. http://eprints.unimelb.edu.au/archive/00003631.
Full text
8
ZAURIN, RICARDO. "STRUCTURAL HEALTH MONITORING WITH EMPHASIS ON COMPUTER VISION, DAMAGE INDICES, AND STATISTICAL ANALYSIS." Doctoral diss., University of Central Florida, 2009. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3530.
Full textAbstract:
Structural Health Monitoring (SHM) is the sensing and analysis of a structure to detect abnormal behavior, damage and deterioration during regular operations as well as under extreme loadings. SHM is designed to provide objective information for decision-making on safety and serviceability. This research focuses on the SHM of bridges by developing and integrating novel methods and techniques using sensor networks, computer vision, modeling for damage indices and statistical approaches. Effective use of traffic video synchronized with sensor measurements for decision-making is demonstrated. First, some of the computer vision methods and how they can be used for bridge monitoring are presented along with the most common issues and some practical solutions. Second, a conceptual damage index (Unit Influence Line) is formulated using synchronized computer images and sensor data for tracking the structural response under various load conditions. Third, a new index, Nd , is formulated and demonstrated to more effectively identify, localize and quantify damage. Commonly observed damage conditions on real bridges are simulated on a laboratory model for the demonstration of the computer vision method, UIL and the new index. This new method and the index, which are based on outlier detection from the UIL population, can very effectively handle large sets of monitoring data. The methods and techniques are demonstrated on the laboratory model for damage detection and all damage scenarios are identified successfully. Finally, the application of the proposed methods on a real life structure, which has a monitoring system, is presented. It is shown that these methods can be used efficiently for applications such as damage detection and load rating for decision-making. The results from this monitoring project on a movable bridge are demonstrated and presented along with the conclusions and recommendations for future work.Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Civil Engineering PhD
9
Kelly, Brendan T. "A Newly Proposed Method for Detection, Location, and Identification of Damage in Prestressed Adjacent Box Beam Bridges." Ohio University / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1339520527.
Full text
10
Waltering, Markus. "Damage assessment of civil engineering structures and bridges using nonlinear dynamic characteristics." Aachen Shaker, 2009. http://d-nb.info/998626988/04.
Full text
11
Khouri, Chalouhi Elisa. "Structural Health Monitoring of Bridges using Machine Learning : The influence of Temperature on the health prediction." Thesis, KTH, Bro- och stålbyggnad, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-189772.
Full textAbstract:
A method that uses machine learning to detect and localize damage in railway bridges under various environmental conditions is proposed and validated in this work. The developed algorithm uses vertical and lateral deck accelerations as damage- sensitive features. Indeed, an Artificial Neural Network (ANN) is trained to predict deck accelerations in undamaged condition given: previous vibration data, air temperature and characteristics of the train crossing the bridge (speed, load position and load magnitude). After an appropriate training period, the comparison between ANN-predicted and measured accelerations allows to compute prediction errors. A Gaussian Process is then used to stochastically characterize prediction errors in undamaged conditions using train speed as independent variable. Recorded vibration data leading to abnormal prediction errors are flagged as damage. The method is validated both on a simple numerical example and on data recorded on a real structure. In the latter case, an appropriate algorithm was developed with the aim of extracting vehicles characteristics from the acceleration time histories. Together with this part of the algorithm for the pre-processing of recorded accelerations, the novelty of the developed method is the addition of air temperature to the input. It allows separating between structure responses that can be flagged as damage from those only affected by environmental conditions.
12
Waltering, Markus [Verfasser]. "Damage Assessment of Civil Engineering Structures and Bridges using Nonlinear Dynamic Characteristics / Markus Waltering." Aachen : Shaker, 2009. http://d-nb.info/1161301380/34.
Full text
13
Lu, Ping. "A statistical based damage detection approach for highway bridge structural health monitoring." [Ames, Iowa : Iowa State University], 2008.
Find full text
14
Xing, Shutao. "Structural Identification and Damage Identification using Output-Only Vibration Measurements." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/1067.
Full textAbstract:
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.
15
Ghosh, Kumar Kanti. "Assessment of FRP composite strengthened reinforced concrete bridge structures at the component and systems level through progressive damage and Non-Destructive Evaluation (NDE)." Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2006. http://wwwlib.umi.com/cr/ucsd/fullcit?p3211930.
Full text
16
Yilmaz, Taner. "Seismic Response Of Multi-span Highway Bridges With Two-column Reinforced Concrete Bents Including Foundation And Column Flexibility." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/12610191/index.pdf.
Full textAbstract:
Seismic design of highway bridges has improved as a result of the experience gained from large earthquakes of the last thirty years. Ductility demand and reserved capacity are extremely important response measures used in new bridge designs to assess target damage levels. However, the application of practical design approaches specified in bridge design codes is not well-defined for bridges over flexible foundations. Within the scope of this research, thirty two bridge models having varying column aspect ratio, amount of column longitudinal reinforcement and foundation flexibility parameters are investigated through a series of analyses such as response spectrum analysis and inelastic time-history analysis under &ldquosafety evaluation earthquake&rdquo
hazard level with a return period of 1000 years, and push-over analysis. Using the results of analyses, seismic response of the investigated bridges are identified with several measures such as displacement capacity over demand ratio, global displacement ductility demand, and response modification factor, along with maximum concrete and steel strains of columns. A correlation between concrete and steel strains and seismic response measure values is constructed to estimate damage levels with commonly used response measures. The findings of this research revealed that global displacement ductility demand is not a favorable response measure for assessing damage levels. On the other hand, displacement capacity over demand ratios can be suggested for estimation of damage levels especially where foundation flexibility effects are extensive as system yielding is not taken into consideration.
17
Ruffels, Aaron. "Model-Free Damage Detection for a Small-Scale Steel Bridge." Thesis, KTH, Bro- och stålbyggnad, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-232363.
Full textAbstract:
Around the world bridges are ageing. In Europe approximately two thirds of all railway bridges are over 50 years old. As these structures age, it becomes increasingly important that they are properly maintained. If damage remains undetected this can lead to premature replacement which can have major financial and environmental costs. It is also imperative that bridges are kept safe for the people using them. Thus, it is necessary for damage to be detected as early as possible. This research investigates an unsupervised, model-free damage detection method which could be implemented for continuous structural health monitoring. The method was based on past research by Gonzalez and Karoumi (2015), Neves et al. (2017) and Chalouhi et al. (2017). An artificial neural network (ANN) was trained on accelerations from the healthy structural state. Damage sensitive features were defined as the root mean squared errors between the measured data and the ANN predictions. A baseline healthy state could then be established by presenting the trained ANN with more healthy data. Thereafter, new data could be compared with this reference state. Outliers from the reference data were taken as an indication of damage. Two outlier detection methods were used: Mahalanobis distance and the Kolmogorov-Smirnov test. A model steel bridge with a span of 5 m, width of 1 m and height of approximately 1.7 m was used to study the damage detection method. The use of an experimental model allowed damaged to be freely introduced to the structure. The structure was excited with a 12.7 kg rolling mass at a speed of approximately 2.1 m/s (corresponding to a 20.4 ton axle load moving at 47.8 km/h in full scale). Seven accelerometers were placed on the structure and their locations were determined using an optimal sensor placement algorithm. The objectives of the research were to: identify a number of single damage cases, distinguish between gradual damage cases and identify the location of damage. The proposed method showed promising results and most damage cases were detected by the algorithm. Sensor density and the method of excitation were found to impact the detection of damage. By training the ANN to predict correlations between accelerometers the sensor closest to the damage could be detected, thus successfully localising the damage. Finally, a gradual damage case was investigated. There was a general increase in the damage index for greater damage however, this did not progress smoothly and one case of ‘greater’ damage showed a decrease in the damage index.
18
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.
19
Zanjanizadeh, Vahid. "Use of Finite Element Modeling for Condition Assessment of reinforced Concrete Bridge Colums in Structural Health Monitoring." University of Akron / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=akron1257532604.
Full text
20
Asgrimsson, David Steinar. "Quantifying uncertainty in structural condition with Bayesian deep learning : A study on the Z-24 bridge benchmark." Thesis, KTH, Skolan för elektroteknik och datavetenskap (EECS), 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-251451.
Full textAbstract:
A machine learning approach to damage detection is presented for a bridge structural health monitoring system, validated on the renowned Z-24 bridge benchmark dataset where a sensor instrumented, threespan bridge was realistically damaged in stages. A Bayesian autoencoder neural network is trained to reconstruct raw sensor data sequences, with uncertainty bounds in prediction. The reconstruction error is then compared with a healthy-state error distribution and the sequence determined to come from a healthy state or not. Several realistic damage stages were successfully detected, making this a viable approach in a data-based monitoring system of an operational bridge. This is a fully operational, machine learning based bridge damage detection system, that is learned directly from raw sensor data.En maskininlärningsmetod för strukturell skadedetektering av broar presenteras. Metoden valideras på det kända referensdataset Z-24, där en sensor-instrumenterad trespannsbro stegvist skadats. Ett Bayesianskt neuralt nätverk med autoenkoders tränas till att rekonstruera råa sensordatasekvenser, med osäkerhetsgränser i förutsägningen. Rekonstrueringsavvikelsen jämförs med avvikelsesfördelningen i oskadat tillstånd och sekvensen bedöms att komma från ett skadad eller icke skadat tillstånd. Flera realistiska stegvisa skadetillstånd upptäcktes, vilket gör metoden användbar i ett databaserat skadedetektionssystem för en bro i full storlek. Detta är ett lovande steg mot ett helt operativt databaserat skadedetektionssystem.
21
Suntharavadivel, Thuraichamy Guganesan. "Behaviour of shear damaged reinforced concrete beams strengthened with external post-tensioning and clamping." University of Southern Queensland, Faculty of Engineering and Surveying, 2008. http://eprints.usq.edu.au/archive/00006254/.
Full textAbstract:
[Abstract]Over the last few decades, there has been a rapid increase in the volume and weight of heavy vehicles using national road networks. More than half of the bridges around the world are over forty years old. The deterioration of these existing bridges due to increased traffic loading, progressive structural aging, and reinforcement corrosion from severe environmental conditions has become a major problem in most countries. Several techniques have been used to strengthen these structures around the world. External post-tensioning is one of the widely used strengthening techniques in many countries due to its advantages over other methods. Furthermore, flexural strengthening using external post-tensioning has become a well established technique over the past few decades. However, when external post-tensioning is used to strengthen shear damaged reinforced concrete members, unlike flexural damage, the efficiency is significantly reduced by existing shear cracks.This research study was carried out to investigate the behaviour of reinforced concrete beams with existing shear cracks when strengthened by external means. The study consists of two parts: experimental investigations of reinforced concrete beams with different parameters and numerical analysis of reinforced concrete beams usingsimplified theoretical formulation and finite element modelling.To study the behaviour of shear damaged concrete beams, two different strengthening techniques, namely external post-tensioning and external clamping, were used. In addition to the strengthening, the effect of cracks on the behaviour of reinforced concrete beams was investigated by repairing such cracks using epoxy resin injection. Experimental results showed that existing shear cracks have a substantial effect on the member capacity when strengthened by external posttensioning. Although there are concerns about the practical applications of externalclamping, the experimental results suggest that external clamping could be a more effective technique than external post-tensioning to reduce the effect of existing shear cracks on the behaviour of concrete beams. Furthermore, proper repair of the shear cracks could significantly reduce their impact.In the numerical analysis, a simplified mathematical approach was developed to estimate the capacity of shear damaged reinforced concrete beam by expanding themodified compression field theory (MCFT). In addition to the simplified theoretical formulation, a finite element model was developed using the commercial finite element package, Abaqus. Comparison between the predicted behaviour using finite element analysis (FEA) and the experimental data illustrated that the developed finite element model could be used as a reliable tool to estimate the capacity of shear damaged reinforced concrete beams. A parametric study was conducted to investigate the effect of different parameters such as concrete strength, amount of shear reinforcement and crack width, using the developed finite element model. From the numerical study, it was concluded that the simplified approach developedin this study can be used as a reliable and conservative technique to predict the member capacity of a cracked reinforced concrete beam strengthened by external means. Furthermore, the parametric study showed that crack width is the most sensitive parameter that affects the capacity of a cracked beam strengthened by external post-tensioning.Based on this research study it can be concluded that existing shear cracks have a substantial effect on the behaviour of reinforced concrete beams strengthened byexternal post-tensioning. The simplified mathematical approach developed in this study can be used to estimate the capacity of such beams.
22
González, Ignacio. "Study and Application of Modern Bridge Monitoring Techniques." Licentiate thesis, KTH, Bro- och stålbyggnad, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-48583.
Full textAbstract:
The field of monitoring is one of rapid development. Advances in sensor technologies, in data communication paradigms and data processing algorithms all influence the possibilities of Structural Health Monitoring, damage detection, traffic monitoring and other implementations of monitoring systems. Bridges are a very critical part of a country’s infrastructure, they are expensive to build and maintain, and many uncertainties surround important factors determining the serviceability and deterioration of bridges. As such, bridges are good candidates for monitoring. Monitoring can extend the service life and avoid or postpone replacement, repair or strengthening work. Many bridges constitute a bottleneck in the transport network they serve with few or no alternative routes. The amount of resources saved, both to the owner and the users, by reducing the amount of non-operational time can easily justify the extra investment in monitoring. This thesis consists of an extended summary and three appended papers. The thesis presents advances in sensor technology, damage identification algorithms and Bridge Weigh-In-Motion techniques. Two case studies are carried out. In the first a bridge and traffic monitoring system is implemented in a highway suspension bridge to study the cause of unexpected wear in the bridge bearings. In the second a fully operational Bridge Weigh-In-Motion system is developed and deployed in a steel railway bridge. The gathered data was studied to obtain a characterization of the site specific traffic.QC 20111122
23
Le, Guillarme Jonathan, and Jakob Lindstam. "Implementering av Structural Health Monitoring : SHM - system för detektering och övervakning av vanligt förekommande skador på betongbroar." Thesis, KTH, Byggteknik och design, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-259696.
Full textAbstract:
Sverige har som många länder runt om i världen en åldrande infrastruktur och behovet av underhåll stiger. I en artikel i Svenska Dagbladet från 21/9–2018 redovisar analys- och teknikkonsultföretaget WSP en grov uppskattning att 300 miljarder kronor behöver investeras för att rusta upp existerande infrastruktur. Efter upprustningen skulle det krävas ca 25 miljarder kronor årligen för att utföra löpande tillståndsbedömning och underhåll av Sveriges väg- och järnvägsnät. Idag används inspektioner för att bedöma broars tillstånd. Det finns tre olika inspektionstyper; huvudinspektion, allmäninspektion och särskild inspektion. Structural Health Monitoring (SHM) är en teknik som globalt används mer och mer som en metod vid tillståndsbedömning av broar. SHM siktar mot att i realtid utföra automatisk bedömning av hela konstruktionens och de enskilda skadornas tillstånd. SHM använder sig av sensorer placerade på kritiska positioner för att samla in mätdata som jämförs med i förtid definierade gränsvärden. I Sverige används SHM sparsamt idag där kunskapen ligger på akademisk nivå och det råder en osäkerhet om hur SHM ska implementeras i praktiken. Genom att implementera SHM, kan skador upptäckas i ett tidigt skede och minimeras genom att snabbt utföra reparationer på konstruktionen innan skadorna blivit kritiska. Studien syftar till att producera en rapport som kan användas som en guide för hur SHM kan implementeras samt visa på hur SHM-systemen har implementerats på tidigare projekt. Rapporten skall ge läsaren en helhetsbild över hur tillståndsbedömning går till idag, vilka skador som är vanligt förekommande samt hur SHM kan användas som ett verktyg vid tillståndsbedömning. Rapporten syftar också till att ge en övergripande förklaring på svenska av SHM-tekniken och vad som behövs för implementering. Öppna ostrukturerade intervjuer genomfördes med forskare inom SHM och skador på betongkonstruktioner samt sakkunniga inom tillståndsbedömning. Intervjuerna användes som utgångspunkt för vidare studier av vanligt förekommande skador och SHM-tekniker. I litteraturstudien användes olika vetenskapliga databaser såsom Diva och ScienceDirect, samt KTH:s bibliotek för att få fram tidigare material om betongskador på broar, deras skademekanismer och om SHM-tekniken. Vidare hämtades information från ett antal doktorsavhandlingar, artiklar och tidigare examensarbeten. Genom litteraturstudie och intervjuer med sakkunniga kom studien fram till att armeringskorrosion och sprickor i betongen är skador som är vanligt förekommande i betongbroar. Skadornas skademekanismer beskrivs i rapporten. Studien identifierade tre olika system som kan användas för detektering och övervakning av armeringskorrosion och sprickor, de systemen är akustisk emission, SOFO-system (SOFO är en förkortning för Surveillance d'Ouvrage par Fibers Optics) och MuST-system (MuST är ett kommersiellt namn). Rapporten ger exempel på hur systemen kan användas för detektering och övervakning av skadorna genom att presentera fyra fallstudier där systemen har använts. Två av fallstudierna presenterar hur akustisk emission har implementeras och två av fallstudierna presenterar hur SOFO-systemet har implementerats. Studien kunde inte identifiera någon fallstudie för MuST-systemet och hur systemet har implementerats. Slutsatsen av studien är att SHM kan användas som ett komplement vid tillståndsbedömningar men man kan inte utföra automatiserade tillståndsbedömningar idag.Like many countries around the world, Sweden has an aging infrastructure and the need for maintenance is increasing. In an article in Svenska Dagbladet from 21 / 9–2018, the analysis and engineering consulting company WSP reports a rough estimate that SEK 300 billion needs to be invested to upgrade existing infrastructure. After the upgrade, it would require approximately SEK 25 billion annually to carry out ongoing condition assessment and maintenance of Sweden's road and railway networks. Today, inspections are used to assess the condition of bridges. There are three types of inspection; main inspection, general inspection and special inspection. Structural Health Monitoring (SHM) is a technology that is globally more used as a method for condition assessment of bridges. SHM aims to perform automatic assessment of the state of the entire construction and individual damages in real time. SHM uses sensors placed at critical positions to collect measurement data compared to pre-defined limit values. In Sweden, SHM is used sparingly today, where knowledge is at an academic level and there is uncertainty about how SHM should be implemented in practice. By implementing SHM, damage can be detected at an early stage and minimized by quickly performing repairs on the design before the damage becomes critical. The study aims to produce a report that can be used as a guide on how SHM can be implemented and show how the SHM systems have been implemented on previous projects. The report should give the reader an overall picture of how condition assessment is performed today, which damages are common and how SHM can be used as a tool when assessing the condition. The report also aims to provide an overall explanation in Swedish of the SHM technology and what is needed for implementation. Open unstructured interviews were conducted with researchers within SHM and damages to concrete structures as well as experts in condition assessment. The interviews were used as a starting point for further studies of commonly occurring damages and SHM techniques. In the literature study, various scientific databases were used, such as Diva and ScienceDirect, as well as KTH's library to obtain earlier material on concrete damage to bridges, its damage mechanisms and about SHM technology. Furthermore, information was obtained from a number of doctoral dissertations, articles and previous degree projects. Through literature study and interviews with experts, the study concluded that reinforcement corrosion and cracks in the concrete are damages that are commonly found in concrete bridges. The damage mechanisms are described in the report. The study identified three different systems that can be used for detection and monitoring of reinforcement corrosion and cracks, those systems are acoustic emission, SOFO system (SOFO is an abbreviation for Surveillance d'Ouvrage pair of Fiber's Optics) and MuST system (MuST is a commercial name). The report gives examples of how the systems can be used for the detection and monitoring of the damages by presenting four case studies where the systems have been used. Two of the case studies present how acoustic emission has been implemented and two of the case studies present how the SOFO-system has been implemented. The study could not identify any case study for the MuST-system and how the system was implemented. The conclusion of the study is that SHM can be used as a supplement to condition assessments but cannot for the time being used for performing automated condition assessments today.
24
Wood, Michael G. "Damage analysis of bridge structures using vibrational techniques." Thesis, Aston University, 1992. http://publications.aston.ac.uk/11832/.
Full textAbstract:
Much research is currently centred on the detection of damage in structures using vibrational data. The work presented here examined several areas of interest in support of a practical technique for identifying and locating damage within bridge structures using apparent changes in their vibrational response to known excitation. The proposed goals of such a technique included the need for the measurement system to be operated on site by a minimum number of staff and that the procedure should be as non-invasive to the bridge traffic-flow as possible. Initially the research investigated changes in the vibrational bending characteristics of two series of large-scale model bridge-beams in the laboratory and these included ordinary-reinforced and post-tensioned, prestressed designs. Each beam was progressively damaged at predetermined positions and its vibrational response to impact excitation was analysed. For the load-regime utilised the results suggested that the infuced damage manifested itself as a function of the span of a beam rather than a localised area. A power-law relating apparent damage with the applied loading and prestress levels was then proposed, together with a qualitative vibrational measure of structural damage. In parallel with the laboratory experiments a series of tests were undertaken at the sites of a number of highway bridges. The bridges selected had differing types of construction and geometric design including composite-concrete, concrete slab-and-beam, concrete-slab with supporting steel-troughing constructions together with regular-rectangular, skewed and heavily-skewed geometries. Initial investigations were made of the feasibility and reliability of various methods of structure excitation including traffic and impulse methods. It was found that localised impact using a sledge-hammer was ideal for the purposes of this work and that a cartridge `bolt-gun' could be used in some specific cases.
25
Liu, Chang. "Drive-By Bridge Damage Identification Through Virtual Simulations." Thesis, North Dakota State University, 2019. https://hdl.handle.net/10365/31624.
Full textAbstract:
With massive infrastructures built in US, timely condition assessment of these infrastructures becomes critical to daily traffic and economics. Due to high cost, long time consumption of direct condition assessment methods, such as closing traffic for sensor installation and monitoring, indirect bridge monitoring has become a promising method. However, the technology is in its initial stage and needs substantial refinement. In this research, virtual simulation approaches, both in 2D and 3D, are used to model the bridge and vehicle interaction through ABAQUS. Artificial Damages were embedded to the model according to different locations and different levels of intensities. With the modelled outcomes, the hypothesis of identifying damages through the responses of the vehicle will be tested. From the simulated vehicle responses, bridge frequencies and damage locations and sizes could be identified accurately through short time flourier transformation and mode shape difference.
26
Neeli, Yeshwanth Sai. "Use of Photogrammetry Aided Damage Detection for Residual Strength Estimation of Corrosion Damaged Prestressed Concrete Bridge Girders." Thesis, Virginia Tech, 2020. http://hdl.handle.net/10919/99445.
Full textAbstract:
Corrosion damage reduces the load-carrying capacity of bridges which poses a threat to passenger safety. The objective of this research was to reduce the resources involved in conventional bridge inspections which are an important tool in the condition assessment of bridges and to help in determining if live load testing is necessary. This research proposes a framework to link semi-automated damage detection on prestressed concrete bridge girders with the estimation of their residual flexural capacity. The framework was implemented on four full-scale corrosion damaged girders from decommissioned bridges in Virginia. 3D point clouds of the girders reconstructed from images using Structure from Motion (SfM) approach were textured with images containing cracks detected at pixel level using a U-Net (Fully Convolutional Network). Spalls were detected by identifying the locations where normals associated with the points in the 3D point cloud deviated from being perpendicular to the reference directions chosen, by an amount greater than a threshold angle. 3D textured mesh models, overlaid with the detected cracks and spalls were used as 3D damage maps to determine reduced cross-sectional areas of prestressing strands to account for the corrosion damage as per the recommendations of Naito, Jones, and Hodgson (2011). Scaling them to real-world dimensions enabled the measurement of any required dimension, eliminating the need for physical contact.
The flexural capacities of a box beam and an I-beam estimated using strain compatibility analysis were validated with the actual capacities at failure sections determined from four destructive tests conducted by Al Rufaydah (2020). Along with the reduction in the cross-sectional areas of strands, limiting the ultimate strain that heavily corroded strands can develop was explored as a possible way to improve the results of the analysis. Strain compatibility analysis was used to estimate the ultimate rupture strain, in the heavily corroded bottommost layer prestressing strands exposed before the box beam was tested. More research is required to associate each level of strand corrosion with an average ultimate strain at which the corroded strands rupture. This framework was found to give satisfactory estimates of the residual strength. Reduction in resources involved in current visual inspection practices and eliminating the need for physical access, make this approach worthwhile to be explored further to improve the output of each step in the proposed framework.Master of Science
Corrosion damage is a major concern for bridges as it reduces their load carrying capacity. Bridge failures in the past have been attributed to corrosion damage. The risk associated with corrosion damage caused failures increases as the infrastructure ages. Many bridges across the world built forty to fifty years ago are now in a deteriorated condition and need to be repaired and retrofitted. Visual inspections to identify damage or deterioration on a bridge are very important to assess the condition of the bridge and determine the need for repairing or for posting weight restrictions for the vehicles that use the bridge. These inspections require close physical access to the hard-to-reach areas of the bridge for physically measuring the damage which involves many resources in the form of experienced engineers, skilled labor, equipment, time, and money. The safety of the personnel involved in the inspections is also a major concern. Nowadays, a lot of research is being done in using Unmanned Aerial Vehicles (UAVs) like drones for bridge inspections and in using artificial intelligence for the detection of cracks on the images of concrete and steel members. Girders or beams in a bridge are the primary longitudinal load carrying members. Concrete inherently is weak in tension. To address this problem, High Strength steel reinforcement (called prestressing steel or prestressing strands) in prestressed concrete beams is pre-loaded with a tensile force before the application of any loads so that the regions which will experience tension under the service loads would be subjected to a pre-compression to improve the performance of the beam and delay cracking. Spalls are a type of corrosion damage on concrete members where portions of concrete fall off (section loss) due to corrosion in the steel reinforcement, exposing the reinforcement to the environment which leads to accelerated corrosion causing a loss of cross-sectional area and ultimately, a rupture in the steel. If the process of detecting the damage (cracks, spalls, exposed or severed reinforcement, etc.) is automated, the next logical step that would add great value would be, to quantify the effect of the damage detected on the load carrying capacity of the bridges. Using a quantified estimate of the remaining capacity of a bridge, determined after accounting for the corrosion damage, informed decisions can be made about the measures to be taken. This research proposes a stepwise framework to forge a link between a semi-automated visual inspection and residual capacity evaluation of actual prestressed concrete bridge girders obtained from two bridges that have been removed from service in Virginia due to extensive deterioration. 3D point clouds represent an object as a set of points on its surface in three dimensional space. These point clouds can be constructed either using laser scanning or using Photogrammetry from images of the girders captured with a digital camera. In this research, 3D point clouds are reconstructed from sequences of overlapping images of the girders using an approach called Structure from Motion (SfM) which locates matched pixels present between consecutive images in the 3D space. Crack-like features were automatically detected and highlighted on the images of the girders that were used to build the 3D point clouds using artificial intelligence (Neural Network). The images with cracks highlighted were applied as texture to the surface mesh on the point cloud to transfer the detail, color, and realism present in the images to the 3D model. Spalls were detected on 3D point clouds based on the orientation of the normals associated with the points with respect to the reference directions. Point clouds and textured meshes of the girders were scaled to real-world dimensions facilitating the measurement of any required dimension on the point clouds, eliminating the need for physical contact in condition assessment. Any cracks or spalls that went unidentified in the damage detection were visible on the textured meshes of the girders improving the performance of the approach. 3D textured mesh models of the girders overlaid with the detected cracks and spalls were used as 3D damage maps in residual strength estimation. Cross-sectional slices were extracted from the dense point clouds at various sections along the length of each girder. The slices were overlaid on the cross-section drawings of the girders, and the prestressing strands affected due to the corrosion damage were identified. They were reduced in cross-sectional area to account for the corrosion damage as per the recommendations of Naito, Jones, and Hodgson (2011) and were used in the calculation of the ultimate moment capacity of the girders using an approach called strain compatibility analysis. Estimated residual capacities were compared to the actual capacities of the girders found from destructive tests conducted by Al Rufaydah (2020). Comparisons are presented for the failure sections in these tests and the results were analyzed to evaluate the effectiveness of this framework. More research is to be done to determine the factors causing rupture in prestressing strands with different degrees of corrosion. This framework was found to give satisfactory estimates of the residual strength. Reduction in resources involved in current visual inspection practices and eliminating the need for physical access, make this approach worthwhile to be explored further to improve the output of each step in the proposed framework.
27
Webb, Graham Thomas. "Structural health monitoring of bridges." Thesis, University of Cambridge, 2014. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.708027.
Full text
28
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.
Full text
29
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.
Full text
30
Alteri, Nicholas James. "Flexural Behavior of Laterally Damaged Full-Scale Bridge Girders Through the Use of Carbon Fiber Reinforced Polymers (CFRP)." UNF Digital Commons, 2012. http://digitalcommons.unf.edu/etd/412.
Full textAbstract:
ABSTRACT
The repair and strengthening of concrete bridge members with CFRP has become increasingly popular over recent years. However, significant research is still needed in order to develop more robust guidelines and specifications. The research project aims to assist with improving design prosedures for damaged concrete members with the use of CFRP.
This document summarizes the analysis and testing of full-scale 40’ foot long prestressed concrete (PSC) bridge girders exposed to simulated impact damage and repaired with carbon fiber reinforced polymers (CFRP) materials. A total of five AASHTO type II bridge girders fabricated in the 1960’s were taken from an existing bridge, and tested at the Florida Department of Transportation FDOT structures lab in Tallahassee, Florida. The test specimens were tested under static loading to failure under 4-point bending.
Different CFRP configurations were applied to each of the girders. Each of the test girders performed very well as each of them held a higher capacity than the control girder. The repaired girders 5, 6 and 7 surpassed the control girder’s capacity by 10.88%, 15.9% and 11.39%. These results indicate that repairing laterally damaged prestressed concrete bridge girders with CFRP is an effective way to restore the girders flexural capacity.
31
Davalos, Elizabeth (Davalos R. ). 1975. "Structural behaviour of cable-stayed bridges." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/80924.
Full text
32
Sazonov, Eduard S. "A case study for building an automated damage detection system." Morgantown, W. Va. : [West Virginia University Libraries], 1999. http://etd.wvu.edu/templates/showETD.cfm?recnum=1000.
Full textAbstract:
Thesis (M.S.)--West Virginia University, 1999.Title from document title page. Document formatted into pages; contains xiv, 429 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 117-118).
33
Chang, Manseok. "Damage criteria for high way bridges subjected to blasting excitations." Ohio : Ohio University, 1990. http://www.ohiolink.edu/etd/view.cgi?ohiou1183487539.
Full text
34
Webster, Michael Peter. "The assessment of corrosion-damaged concrete structures." Thesis, University of Birmingham, 2000. http://etheses.bham.ac.uk//id/eprint/259/.
Full textAbstract:
Data from existing research are linked together to produce an overview of the effects of chloride-induced corrosion on reinforced concrete structures. The effects of chloride-induced corrosion on the following mechanisms have been investigated: (i) Cracking. (ii) Bond strength. (iii) Flexural strength. (iv) Shear strength. (v) Column behaviour. Models have been developed to link material and structural aspects of deterioration. Despite the complexity of the behaviour, many of the models are modifications to existing procedures contained in UK codes. Material and structural models are integrated together in a spreadsheet for assessing the variation in load-carrying capacity with time. Time to cracking and residual load-carrying capacity are found to be sensitive to small variations in key parameters such as the cover and the surface chloride level. Predictions from a spreadsheet model indicate that structures designed and built to BS 8110 should achieve their design life without the need for significant repair. The predictions also indicate that the UK Highways Agency was justified in making BD 57 more onerous than BS 5400. With validation against further test data the procedures developed in this Thesis could form the basis for codes of practice for the assessment of corrosion-damaged concrete structures and the durability design of new concrete structures.
35
Mya, San Wai. "Robustness Evaluation of Long Span Truss Bridge Using Damage Influence Lines." Kyoto University, 2020. http://hdl.handle.net/2433/253253.
Full text
36
Li, Zhenhu, and 李振虎. "Damage identification of bridges from signals measured with a moving vehicle." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2014. http://hdl.handle.net/10722/206353.
Full textAbstract:
Identifying damage of a bridge from a vehicle moving over it is an attractive idea especially for those bridges without structural health monitoring systems as it is faster than putting sensors on the bridges. Many parts of highways and railways have been constructed on bridges and it is important to ensure that they are in good conditions. Therefore a large amount of bridges need to be monitored and for the sake of economy the monitoring should be efficient. If an instrumented vehicle can identify the occurrence and locations of damage by running over the bridges, it would save a lot of labor and time. As acceleration is easier to acquire, it is used as the main signal for damage detection. Research in this area is relatively little, not to mention the need to take into account road surface roughness and experimental verification.
Frequencies can be conveniently extracted from the vehicle response. The damage can hence be identified based on the relationship between the change of frequencies and the fractional change of strain energy. A vehicle-bridge interaction system is used to simulate the process of a vehicle running over a bridge and obtain the vehicle response for investigation. The proposed method can identify damage of simply supported and multi-span continuous bridges taking into account road surface roughness and measurement noise. They are also validated in the laboratory where a simply supported bridge is modeled using an aluminum beam and the vehicle is modeled with aluminum vehicles. This method can limit the damage location to two potential locations.
The multi-level multi-pass strategy makes use of the identification from the above method, applies genetic algorithm and lets the vehicle run over the bridge at various speeds. The unique damage location can then be identified. A numerical study for simply supported bridges and multi-span continuous bridges has verified its effectiveness.
Continuous wavelet transform (CWT) can identify local changes in a signal as damage is assumed to cause local change to the vehicle response, which makes it suitable for damage detection from vehicle response. However, the road surface roughness and measurement noise often mask the information about damage. Smoothing technique and damage indicators are proposed to help with the identification. By validating the method with a numerical vehicle-bridge interaction system and model tests in the laboratory, the damage can be correctly identified. Additional masses and sinusoidal excitation force can help with the identification too.
Repeated application of CWT involves applying the CWT to the coefficients of continuous wavelet again and again, which can also improve the results. If CWT is treated as a mathematical microscope, repeated application of CWT is like amplifying the signal several times. The effectiveness of the method has been verified numerically and experimentally.
In summary, a convenient and efficient technique to test the conditions of bridges by putting sensors on a moving vehicle is proposed and the method is verified by numerical and experimental studies. It can provide an alternative or a useful complement to conventional structural health monitoring systems.published_or_final_version
Civil Engineering
Doctoral
Doctor of Philosophy
37
Schallhorn, Charles Joseph. "Coherence-based transmissibility as a damage indicator for highway bridges." Diss., University of Iowa, 2015. https://ir.uiowa.edu/etd/2007.
Full textAbstract:
Vibration-based damage detection methods are used in structural applications to identify the global dynamic response of the system. The purpose of the work presented is to exhibit a vibration-based damage detection algorithm that calculates a damage indicator, based on limited frequency bands of the transmissibility function that have high coherence, as a metric for changes in the dynamic integrity of the structure. The methodology was tested using numerical simulation, laboratory experimentation, and field testing with success in detecting, comparatively locating, and relatively quantifying different damages while also parametrically investigating variables which have been identified as issues within similar existing methods. Throughout both the numerical and laboratory analyses, the results were used to successfully detect damage as a result of crack growth or formation of new cracks. Field results using stochastic operational traffic loading have indicated the capability of the proposed methodology in evaluating the changes in the health condition of a section of the bridge and in consistently detecting cracks of various sizes (30 to 60 mm) on a sacrificial specimen integrated with the bridge abutment and a floor beam. Fluctuations in environmental and loading conditions have been known to create some uncertainties in most damage detection processes; however, this work demonstrated that by limiting the features of transmissibility to frequency ranges of high coherence, the effect of these parameters, as compared to the effect of damage, become less significant and can be neglected for some instances. The results of additional field testing using controlled impact forces on the sacrificial specimen have reinforced the findings from the operational loading in detecting damage.
38
Telste, Michael Andrew. "Damage Localization of Slab-on-Girder Bridges Through Vibration Characteristics." Thesis, North Dakota State University, 2015. https://hdl.handle.net/10365/27657.
Full textAbstract:
An incompletely documented bridge 09-125-16 in Cass County, ND was tested by Bridge Diagnostics, Inc. (BDI). A Grillage numerical model is created with their field data to simulate the bridge responses due to traffic loads. A validated bridge model matching the field test data is developed.
Based on the validated numerical model, loading of the corresponding bridge under different damage scenarios is performed to capture the change of displacement mode shapes. Using the difference of these displacement mode shape data, a modified curvature method is suggested for identifying damage in bridges, which is shown successfully through the modeling results of bridges with fictitious damages. An in-lab experiment of a steel plate without damage under impact forces is adopted to produce vibration data. The modified curvature is then computed using the experimental mode shape data and its change is found to correlate very well as anticipated by the suggested theory.
39
Chen, ZhiQiang. "Identifying structural damage from images." Diss., Connect to a 24 p. preview or request complete full text in PDF format. Access restricted to UC campuses, 2009. http://wwwlib.umi.com/cr/ucsd/fullcit?p3337297.
Full textAbstract:
Thesis (Ph. D.)--University of California, San Diego, 2009.Title from first page of PDF file (viewed January 9, 2009). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (p. 250-263).
40
Ellick, Jane Caroline Ann. "Vibration characteristics of masonry arch bridges." Thesis, University of Reading, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.262545.
Full text
41
Hejll, Arvid. "Structural health of bridges: monitor, asess and retrofit /." Luleå, 2004. http://epubl.luth.se/1402-1757/2004/46.
Full text
42
Hejll, Arvid. "Structural health of bridges : monitor, assess and retrofit." Licentiate thesis, Luleå, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-25805.
Full textAbstract:
The research presented in this Licentiate thesis is intended to cover minor areas of the wide research area Structural Health Monitoring (SHM) of Civil Engineering Structures. SHM is broadly the knowledge maintaining our infrastructure by assessing the condition, often by monitoring or measurements, diagnose damages, analyse risk levels, by using inputs from measurements and diagnoses, and in the end retrofit, if needed. In particular the methodology and the interaction between the different parts in SHM, ranging from assessment to upgrading, are explained. The thesis give also a brief introduction to sensor technology, mainly designed for monitoring, and to damage detection methods in Civil Engineering structures, such as bridges. The thesis is of the form "combination thesis" which is characterised by a relatively extensive literature study and a summary of the research presented at the beginning. Beyond this, it contains four papers, which are summarised below. Paper A: "Concrete beams exposed to Live Loading during CFRP strengthening", presents how strengthening of concrete beams can be done without stopping the traffic during execution. Results show that no significant decrease of the strengthening effect exists when carbon fibre laminates and quadratic rods (NSMR), is bonded with an epoxy adhesive, which had cured during the cyclic loading. If a cementitious bonding agent is used, cyclic loading decrease the strengthening effect dramatically. Paper B: "Large scale hybrid composite FRP girders for use in bridge structures - theory, test and field application". This paper presents the possibility to build a bridge in full scale using fiber reinforced polymers. Numerical analysis, full scale tests and theoretical investigations shows full composite action between the constituents. Paper C: "CFRP Strengthening and monitoring of the Gröndals Bridge in Sweden" discuss the retrofit of a large concrete box bridge using CFRP laminates and how the strengthening effect can be monitored and verified using fibre optical sensors (FOS). Due to shear cracks in the webs the Gröndals Bridge is strengthened with CFRP-laminates and post stressed with steel stays. Monitoring with FOS and conventional LVDT gauges shows that most of the measured strain is caused by natural temperature changes. The results also show that the CFRP laminates work as intended and that the crack propagation has stopped. Paper D: "Damage Detection of a Large-Scale 38-Years-Old Prestressed RC Bridge Girder using Natural Frequencies" gives and example how modal analysis can be used as a diagnostic tool to indicate damages. The results show very small changes of natural frequencies because no cracks during the whole tests occurred and the Young's modulus of the concrete was increasing after unloading.Godkänd; 2004; 20070131 (ysko)
43
Wang, Xiaoyi. "Structural Condition Assessment of Steel Stringer Highway Bridges." University of Cincinnati / OhioLINK, 2005. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1115351511.
Full text
44
Bensi, Michelle T. "Generalized assessment of bridge vulnerability to terrorist threats a probabilistic structural analysis based approach /." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 8.47 Mb., 191 p, 2006. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pqdiss&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&rft_dat=xri:pqdiss:1435875.
Full text
45
Muhamad, Bunnori Norazura. "Acoustic emission techniques for the damage assessment of reinforced concrete structures." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54633/.
Full text
46
Salawu, Olusegun Saheed. "Structural integrity assessment using vibration data." Thesis, University of Plymouth, 1994. http://hdl.handle.net/10026.1/2614.
Full textAbstract:
Engineering structures need to be assessed as part of activities to ensure their continued serviceability. Global methods of assessment which also give an indication of local conditions are most attractive since they are cost effective and flexible. A suitable method with these attributes is vibration monitoring which involves relating dynamic properties, or changes in them, to the integrity of the assessed structure. The present study investigates the application of vibration testing to structural integrity assessment of civil engineering structures. A survey of existing methods of damage detection, location and quantification in structures using vibration testing was conducted. Evaluation of the performance of some of the more promising methods was conducted using both simulated and experimental data. The results revealed that the damage identification process could be enhanced if appropriate modes are used. To this end, a new function, called Modal Sensitivity Values, has been proposed for identifying damage sensitive modes to be included in damage detection and location methods. It was also found that some success could be achieved if system identification and model updating procedures are applied to the problem of damage detection in structures. The literature survey revealed that most of the available methods are not applicable to general structural systems and are often limited by the damage model assumed. A new method, called Integrity Index Damage Location method, of assessing structural integrity using vibration data has also been proposed. The method is applicable to any structure and any damage type that affects the integrity/stiffness of the structure. Performance evaluation of the method using both numerical and experimental data is presented. Full-scale forced vibration tests were conducted before and after repairs on two reinforced concrete highway bridges. The vibrator used during the tests was developed during the research project and details of its development and operation are given in the thesis. As a background to the tests, a review of full-scale dynamic testing of bridge structures was conducted. Results from the tests were used to investigate the effectiveness of forced vibration testing as an integrity monitoring tool. It was found that the repair works caused slight (less than 5%) changes in the natural frequencies while there was no definite trend in the changes to the modal damping ratios. Comparison of frequency response functions and mode shapes, using modal analysis procedures, was found to give an indication of the presence and location of the repairs. The integrity assessment method proposed was also able to identify some of the affected parts of the structures. Results from the full-scale tests were also compared with predictions from finite element analysis. Good correlation was obtained between the measured and calculated natural frequencies and mode shapes, thus enabling validation of the analytical models within limits of the model assumptions and experimental errors. The results demonstrate the importance of accurate representation of boundary conditions. They (results) also showed that the vertical stiffness of new bearings installed on one of the bridges is not as high as was assumed in the design.
47
Liu, Xuefeng. "Vibration-based structural damage identification techniques." Thesis, University of Bristol, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.445826.
Full text
48
Alves, Marcilio. "Damage mechanics applied to structural impact." Thesis, University of Liverpool, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.484220.
Full text
49
Tadros, Nader Nabil Aziz. "Structural damage detection using ambient vibrations." Thesis, Kansas State University, 2014. http://hdl.handle.net/2097/18178.
Full textAbstract:
Master of ScienceDepartment of Civil Engineering
Hani G. Melhem
The objective of this research is to use structure ambient random vibration response to detect damage level and location. The use of ambient vibration is advantageous because excitation is caused by service conditions such as normal vehicle traffic on a highway bridge, train passage on a railroad bridge, or wind loads on a tall building. This eliminates the need to apply a special impact or dynamic load, or interrupt traffic on a bridge in regular service. This research developed an approach in which free vibration of a structure is extracted from the response of this structure to a random excitation in the time domain (acceleration versus time) by averaging out the random component of the response. The result is the free vibration that includes all modes based on the sampling rate on time. Then this free vibration is transferred to the frequency domain using a Fast Fourier Transform (FFT). Variations in frequency response are a function of structural stiffness and member end-conditions. Such variations are used as a measure to identify the change in the structural dynamic properties, and ultimately detect damage. A physical model consisting of a 20 × 20 × 1670 -mm long steel square tube was used to validate this approach. The beam was tested under difference supports conditions varying from a single- to three-span continuous configuration. Random excitation was applied to the beam, and the dynamic response was measured by an accelerometer placed at various locations on the span. A numerical model was constructed in ABAQUS and the dynamic response was obtained from the finite element model subjected to similar excitation as in the physical model. Numerical results were correlated against results from the physical model, and comparison was made between the different span/support configurations. A subsequent step would be to induce damage that simulates loss of stiffness or cracking condition of the beam cross section, and that would be reflected as a change in the frequency and other dynamic properties of the structure. The approach achieved good results for a structure with a limited number of degrees of freedom. Further research is needed for structures with a larger number of degrees of freedom and structures with damage in symmetrical locations relative to the accelerometer position.
50
Kashif, Ahmed H. (Ahmed Hassan) Carleton University Dissertation Engineering Civil. "Dynamic response of highway bridges to moving vehicles." Ottawa, 1992.
Find full text