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Dissertations / Theses on the topic 'ARCH'

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Published: 4 June 2021
Last updated: 8 June 2024

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1

Liadis, Nicholas. "[MUSO-ARCH]itectonics." PDF viewer required Home page for entire collection, 2008. http://archives.udmercy.edu:8080/dspace/handle/10429/9.

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2

Williamson, Thomas James. "Weight optimum arch structures." Thesis, Monterey, California. Naval Postgraduate School, 1992. http://hdl.handle.net/10945/24108.

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The goal of this investigation is to design minimum weight arch structures which span the distance between two points in two-dimensional space. An arch of unknown shape and variable cross-sectional width is modeled as a series of straight bar-beam elements. Finite Element Methods are used to compute the stresses in each element. Automated Design Synthesis (ADS) software is then used to vary the slope of each element and the cross-sectional width to prevent the yield stress of the material from being exceeded as ADS minimizes the arch volume to arrive at the minimum weight structure. Results are presented for a number of different loadings and boundary conditions.
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3

Menzies, Margaret Anne. "Weight optimum arch structures." Thesis, Monterey, California. Naval Postgraduate School, 1991. http://hdl.handle.net/10945/28651.

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4

Tuncer, Ruhi. "Les modèles ARCH multivariés." Paris 9, 1995. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1995PA090011.

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Nous étudions la convergence en probabilité de l'estimateur de maximum de vraisemblance d'un modèle ARMA dont les erreurs suivent un processus GARCH (1, 1) selon la spécification de Baba, Engle, Kraft et Kroner. Nous établissons des conditions d'existence des moments d'ordre supérieur à deux. Les conditions de stationnarité stricte et d'ergodicité de certains modèles contraints sont présentées. Finalement, nous proposons un cadre général pour l'approximation en temps continu de modèles ARCH multivariés
We study the convergence in probablityof the maximum likelihood estimators of a multivariate ARMA model with GARCH (1,1) errors as specified by Baba, Engle, Kraft and Kroner. We establish conditions under which moments of order superior to ergodicit of certain constrained models are presented. Finally we propose a general framework for multivariate ARCH models as diffusion approximations
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5

McDavid, Charles Scott. "Weight optimum arch structures." Thesis, Monterey, California : Naval Postgraduate School, 1990. http://handle.dtic.mil/100.2/ADA245954.

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Thesis (M.S. in Mechanical Engineering)--Naval Postgraduate School, December 1990.
Thesis Advisor(s): Salinas, David. "December 1990." Description based on title screen as viewed on April 1, 2010. DTIC Identifier(s): Arches, Stress Analysis, Weight, Finite Element Analysis, Computer Programs, Optimization, Theses, Degrees Of Freedom, FORTRAN, Stiffness, Case Studies. Author(s) subject terms: Finite Element Method, Arches, Weight Optimization. Includes bibliographical references (p. 107). Also available in print.
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6

Hashemidehaghi, Sogol. "The Isfahan's inhabited arch bridges." Master's thesis, Universidade de Évora, 2019. http://hdl.handle.net/10174/27681.

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Ispahan est l’une des villes historiques qui se trouve au centre d'Iran. La ville est célebre pour sa belle architecture islamique. ses ponts couverts, ses mosquées uniques et ses minarets. Cela a fait d'lspahan le titre de "la moitié du monde " dans la culture populaire. Les cinq ponts historiques Zayandeh Rud à lspahan sont un chef-d'oeuvre de l'architecture iranienne, conçus non seulement pour le passage des individus. mais aussi pour traverser les confins de ce monde. la compréhension des valeurs matérielles et imnmatérielles existant dans les ponts historiques d'Ispahan afin. deles protégeres l’un des objectifs principaux de cette thèse. La compréhension des techniques de construction des ponts-arcades à lspahan et ses changements au fil du temps est autre buts de cette recherche qui montre l'intelligence et les talents des lraniens dans la construction de ponts. non seulement en tant que lieu de passage. mais également en tant que lieu de réflexion, de divertissement et de rassemblement, ainsi qu'une structure technique telle que barriêre permettant de contrôler l'écoulernent d'eau; Abstract: lsfàhan is one of the historic cities in the center of lran. This city is the third most populated city of lran which is also rich in history, art and architecture. The largest river of lranian Plateau in central part Iran which name is Zayandeh-Rud also crosses Isfahan and from the past to the present day, this river played an important role in the formation of the civilization and development of the city of lsfàhan. Therefore, due to the constant development of Isfahan throughout history, as well as the existence of a Zayandeh-Rud flow, numerous bridges were built with a various function in this city. These bridges were designed to connect water, wind, nature and the human being in a particular architectural concept. They were not just designed for passage of the individuals or just for connecting two banks of river, but their purpose was also to link spiritual advancernent and human understanding. They have been designed in the way which makes the pedestrians to stay, watch the beauty of nature, listen to it and think. Since the Isfahan’s bridges have different functions, they can be categorized into inhabited bridges.
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7

Sepúlveda, Ana Margarida Queirós. "Modelos Heterocedásticos - ARCH e GARCH." Master's thesis, Faculdade de Economia da Universidade do Porto, 2010. http://hdl.handle.net/10216/57365.

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8

Rönty, T. (Teemu). "ARCH-mallit tuoton volatiliteetin mallintamisessa." Bachelor's thesis, University of Oulu, 2018. http://urn.fi/URN:NBN:fi:oulu-201805231888.

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9

Goh, Julian Kok Seng. "Analysis of Pressurized Arch-Shells." Thesis, Virginia Tech, 1998. http://hdl.handle.net/10919/35576.

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A pressurized arch-shell structural component made of flexible material is considered. The component is inflated with high internal pressure. The behavior of similar types of structures, such as a pair of leaning pressurized arches and pressurized arch-supported membrane shelters, has been investigated in the past. More recently, several types of pressurized structures have been incorporated as part of the framework for a variety of structural systems. Particularly, the U.S. Army has been investigating the use of large lightweight and transportable pressurized arch-shell structures to be used as maintenance shelters for vehicles, helicopters, and airplanes. The formulated equations using thin shell theory are applied to a pressurized arch-shell component. A numerical investigation based on the Rayleigh-Ritz method is utilized to determine the behavior of arch-shells under various types of loading. The types of loading include a uniformly distributed vertical load representing snow, a wind load, and a horizontal side load distributed along the arc length. Deflections, stress resultants, and moments at various locations are computed for two types of shapes: circular and non-circular arch-shells.
Master of Science
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10

Gabra, Joseph Nageh. "Biomechanics of the Carpal Arch." Cleveland State University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=csu1440155265.

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11

Ng, Kwooi-Hock. "Analysis of masonry arch bridges." Thesis, Edinburgh Napier University, 1999. http://researchrepository.napier.ac.uk/Output/3673.

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In January 1999, the maximum axle weight increased from IN to 11.5t for the assessmenot f highway bridges and structures. At the samet ime, the maximum vehicle weight also increased from 38t to 44t. Highway authorities are urgently searching for a more refined assessmenmt ethod to predict the behaviour of masonry arch bridges. LUSAS finite element analysis was used to study the behaviour of masonry arch bridges. Load versus deflection curves and collapse loads are given for some of the full and large scale arches previously tested to collapse. A parametric study was also performed to determine the influence of the arch material properties and the load dispersal angle: the arch tensile strength and the load dispersal angle were found to have the most significant influence on the collapse load predictions. Repeatability tests were carried out by building three nominally identical large scale arch bridges in the laboratory and testing them to collapse. The first, second and third arches collapsed at 2lkNm', 16kNm', and 25kNm 1 respectively. Finite element analysis predicted a range of 18kNm' to 39kNm 1 for the same arches. This led to an examination of a statistical, risk based, approach to bridge assessment. Two novel risk assessment programs were developed by integrating Monte Carlo simulation with the MEXE and the mechanism methods. Statistical information about the predicted collapse load and allowable axle load is given. These risk assessment tools are offered for incorporation within routine assessmenmt ethods. Their principal benefit lies in providing engineers with a feel for the reliability of their analyses. A modification has been made to the mechanism method by considering arch deflection. A mechanism prediction is accurate only when all the forces and their positions are accurately located. The modified mechanism method was used to analyse some of the full scale arch bridges, previously tested to collapse, which revealed that arch deflections had a significant influence on the collapse load prediction.
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12

Pournaghshband, Asal. "Form-finding of arch structures." Thesis, University of Warwick, 2016. http://wrap.warwick.ac.uk/87332/.

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In this thesis, the optimal shape of two-pin arches of constant cross-section is found analytically using a novel form-finding technique. To find the purely compressed arches built of masonry and concrete material, the state of static equilibrium is applied. As the main finding, the momentless two-pin arch shape is derived for the arches with any span-to-height ratio subjected to its self-weight (SW) and uniformly distributed load (UDL). The contribution of using momentless arches is shown through comparing their maximum displacements to those of parabolic shape. The first failure of the cross-section of the momentless and parabolic arches was then compared for the same loading. This work is conducted practising the knowledge of arch response to loading as a function of the chosen form. In this regard, a comprehensive study of the behaviour of different arch shapes considering different ratios of uniformly distributed load to self-weight (UDL:SW) is also carried out. The ideal common arch shape is investigated for minimum combined axial and bending stresses using the commercial software GSA. The optimal range of span-to-height ratio of common two-pin arch shapes is also suggested. In general, the best arch performance is exhibited for the parabolic and catenary arch with span-to-height ratios between 2–4 when UDL:SW≥1 and UDL:SW < 1 respectively. However, the circular arch demonstrates the least desirable performance with the optimum range of span-to-height ratio between 4–6. Moreover, approximate methods of two-pin arch analysis are evaluated, including the masonry design method and virtual work method suggested by Megson (2006). The effect of the assumptions made by these methods on the result of analysing two-pin arches is investigated through comparing their results to those obtained by the second theorem of Castigliano, including full structural action and the GSA results.
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13

Sepúlveda, Ana Margarida Queirós. "Modelos Heterocedásticos - ARCH e GARCH." Dissertação, Faculdade de Economia da Universidade do Porto, 2010. http://hdl.handle.net/10216/57365.

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14

Palaoro, Stefania. "Arch bridges: Design - Construction - Perception." Doctoral thesis, Università degli studi di Trento, 2011. https://hdl.handle.net/11572/367845.

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The arch bridges have an historical development, that is rooted in their ancient tradition, yet are also very successful to this day, a rediscovery of the earliest arched forms can be seen in the most recent innovations. After millennia of masonry arch bridges and almost two centuries of relentless development of iron, steel and concrete arch bridges, with different structural schemes and constructive shapes, there was a moment that this type of structure was bound to disappear. The scope of traditional arch bridges, which refers mainly to the ones of small and medium span, was to become the uncontested role of the girder bridges. The reuse and the assertion of the arch bridge has been accompanied by a strong architectural emphasis on their structural design and constructive details. This relation, increasingly important during the design phase between the concept of FORM and of STRUCTURE, has ensured that many new projects link the strong relationship between TRADITION and technological and constructive INNOVATION. I ponti ad arco sono quelli che presentano un’evoluzione storica che fonda le sue radici nella tradizione più antica, ma anche quelli che ricevono all’oggi il maggior successo, una riscoperta delle prime forme arcuate che ritornano quasi come una moda ma con l’impiego delle recenti innovazioni: dopo millenni di ponti ad arco in muratura e quasi due secoli di inarrestabile sviluppo di ponti ad arco in ghisa, di ferro, acciaio e di cemento armato, accompagnato da diversi schemi strutturali e di forme costruttive, sembrava che questa tipologia fosse destinata a scomparire. Infatti il campo tradizionale dei ponti ad arco che si riferiva soprattutto ai ponti di media luce era divenuto oramai dominio incontrastato dei soli ponti a travata. Il riuso e il riaffermarsi del ponte ad arco è stato accompagnato da una forte accentuazione architettonica della loro concezione strutturale e dei loro dettagli costruttivi. Il rapporto sempre più importante in fase progettuale di correlare il concetto di FORMA con quello di STRUTTURA ha fatto in modo che molte nuove opere d’arte di nuova realizzazione unissero in sé il forte rapporto tra TRADIZIONE e INNOVAZIONE tecnologica e costruttiva.
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15

Palaoro, Stefania. "Arch bridges: Design - Construction - Perception." Doctoral thesis, University of Trento, 2011. http://eprints-phd.biblio.unitn.it/504/1/Stefania_Palaoro_Arch_bridges%2Cdesign-construction-perception.pdf.

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The arch bridges have an historical development, that is rooted in their ancient tradition, yet are also very successful to this day, a rediscovery of the earliest arched forms can be seen in the most recent innovations. After millennia of masonry arch bridges and almost two centuries of relentless development of iron, steel and concrete arch bridges, with different structural schemes and constructive shapes, there was a moment that this type of structure was bound to disappear. The scope of traditional arch bridges, which refers mainly to the ones of small and medium span, was to become the uncontested role of the girder bridges. The reuse and the assertion of the arch bridge has been accompanied by a strong architectural emphasis on their structural design and constructive details. This relation, increasingly important during the design phase between the concept of FORM and of STRUCTURE, has ensured that many new projects link the strong relationship between TRADITION and technological and constructive INNOVATION. I ponti ad arco sono quelli che presentano un’evoluzione storica che fonda le sue radici nella tradizione più antica, ma anche quelli che ricevono all’oggi il maggior successo, una riscoperta delle prime forme arcuate che ritornano quasi come una moda ma con l’impiego delle recenti innovazioni: dopo millenni di ponti ad arco in muratura e quasi due secoli di inarrestabile sviluppo di ponti ad arco in ghisa, di ferro, acciaio e di cemento armato, accompagnato da diversi schemi strutturali e di forme costruttive, sembrava che questa tipologia fosse destinata a scomparire. Infatti il campo tradizionale dei ponti ad arco che si riferiva soprattutto ai ponti di media luce era divenuto oramai dominio incontrastato dei soli ponti a travata. Il riuso e il riaffermarsi del ponte ad arco è stato accompagnato da una forte accentuazione architettonica della loro concezione strutturale e dei loro dettagli costruttivi. Il rapporto sempre più importante in fase progettuale di correlare il concetto di FORMA con quello di STRUTTURA ha fatto in modo che molte nuove opere d’arte di nuova realizzazione unissero in sé il forte rapporto tra TRADIZIONE e INNOVAZIONE tecnologica e costruttiva.
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16

Torstensson, Martin, and Hans Pettersen. "Optimization of front Wheel Arch Liner." Thesis, Linköping University, Department of Mechanical Engineering, 2006. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-5957.

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About ten years ago Volvo Cars could see that car manufactures began to introduce rear wheel arch liners made of non-woven fabrics or some kind of laminate which are mostly common today. Volvo Cars have also seen that competitors now are beginning to develop the front wheel arch liners more and more and expect a development equal to the one for the rear wheel arch liners. This is why we are set to optimize the front wheel arch liner.

For development of mechanical products such as car parts, a discursive method is most suitable to follow. For example systematical concept development which we have used in our work.

From a technical point of view, our results shows that the penta laminate used for the wheel arch liner on Mercedes Benz S-class is by far the best material. Unfortunately it is rather expensive which of course affects its result in a negative way when cost is taken in to consideration. When including cost, the solid plastic is actually rather economical.

After assessment of the result in total we are however convinced that Volvo Cars should concentrate on further research of penta laminate and open negotiations with different suppliers regarding a material of this kind.

Regarding the geometry, the tests and studies that Volvo Cars have performed earlier on splash shields clearly shows the usage of the part and further research done by our selves does not point at any problems with a splash shield integrated in the wheel arch liner.


För ungefär tio år sedan kunde Volvo Cars se att biltillverkare började introducera bakre hjulhus tillverkade av ”non-woven” fibrer eller någon form av laminat vilket idag är högst vanligt. Volvo Cars har också sett att konkurrenter nu börjar utveckla främre hjulhus mer och mer och räknar med en utveckling liknande den för bakre hjulhus. Detta är anledningen till att vi har fått uppgiften att optimera det främre hjulhuset.

För utveckling av mekaniska produkter så som bildelar, är en diskursiv metod mest lämpad att följa. Till exempel systematisk konceptutveckling som vi har valt att använda i vårt arbete.

Sett ur ett tekniskt perspektiv, visar våra resultat att pentalaminatet som används för hjulhusen på Mercedes Benz S-klass, är det överlägset bästa materialet. Tyvärr ar det ganska dyrt vilket naturligtvis påverkar dess resultat negativt när hänsyn tas till kostnader. När vi även ser till kostnaderna, är faktiskt den rena plasten mycket ekonomisk. Efter bedömning av det totala resultatet, är vi helt övertygade om att Volvo Cars borde koncentrera sig på fortsatta undersökningar av pentalaminat och inleda förhandlingar med olika underleverantörer angående material av denna typ.

Angående geometrin, visar Volvo Cars’ sedan tidigare genomförda tester och studier att en splash shield fyller en viktig funktion och vidare undersökningar genomförda av oss själva pekar inte på några problem med en i hjulhuset integrerad splash shield.

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17

Anttila, V. (Vesa). "Brain protection in aortic arch surgery." Doctoral thesis, University of Oulu, 2000. http://urn.fi/urn:isbn:9514256174.

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Abstract Retrograde cerebral perfusion (RCP) techniques have been adopted in aortic arch surgery for clinical use. The clear benefits of RCP are that it reduces embolic injury and prolongs the permissible period of hypothermic circulatory arrest (HCA). At the same time, however, there is a great deal of evidence according to which RCP may be associated with an increased risk of fluid sequestration and cerebral edema. In the current study intermittent RCP was compared with continuous RCP and HCA alone to clarify if periodical RCP decreases fluid sequestration (I). HCA is an effective method of cerebral protection, but is associated with long cardiopulmonary bypass times, and coagulation disturbances. We tested the hypothesis that deep hypothermic RCP could improve cerebral outcome during moderate HCA (II and III). Glutamate excitotoxicity plays an important role in the development of ischemic brain injury. The purpose of the present study was to determine the efficacy of lamotrigine, a Na+ channel blocker, to mitigate cerebral injury after HCA (IV). A chronic porcine model was used in the present series of studies. Hemodynamic, electrophysiologic, and metabolic monitoring were performed until four hours after the instigation of rewarming. S-100β was measured up to 20 hours. Daily behavioral assessment performed until death or elective sacrifice on the seventh postoperative day. After continuous RCP the median fluid sequestration volume was 145 (0–250) ml compared with -50 (-100 - 0) ml after intermittent RCP (p = 0.04). In comparison of 15°C RCP to HCA alone during moderate 25°C hypothermia, 5/6 animals in the RCP group survived seven days compared with 2/6 in the HCA group (p = 0.04). The total histopathologic scores in the RCP(15°C) group were lower than those for the RCP(25°C) group during moderate 25°C hypothermia (p = 0.04). EEG bursts were recovered better in the RCP(15°C) group at 3 hours after the start of rewarming compared to HCA group (p = 0.05). The rate of EEG burst recovery was higher in lamotrigine treated animals compared to placebo treated animals after 4 hours during the rewarming (p = 0.02). Among the animals that survived for 7 days, the median behavioral score was higher in the lamotrigine group (8) compared with controls (7) (p = 0.02). The results indicate that intermittent RCP decreases the rate of fluid sequestration after continuous RCP. The cold RCP at moderate systemic hypothermia seems to provide a better neurological outcome than that with moderate temperature RCP, a finding suggesting that enhanced cranial hypothermia is the major beneficial factor of RCP. The Na+ channel blocker lamotrigine improves neurological outcome after a prolonged period of HCA. In conclusion, two refinements in the RCP concept are to administer it at low temperatures and if longer periods of perfusion are necessary, RCP should be applied intermittently.
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18

Hümpfner-Hierl, Heike, Andreas Schaller, and Thomas Hierl. "Biomechanical investigation of the supraorbital arch." Universitätsbibliothek Leipzig, 2014. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-143957.

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Introduction: As fractures of the supraorbital region are far less common than midfacial or orbital fractures, a study was initiated to investigate whether fist blows could lead to fractures similar to those often seen in the midface. Methods: A detailed skull model and an impactor resembling a fist were created and a fist blow to the supraorbital region was simulated. A transient finite element analysis was carried out to calculate von Mises stresses, peak force, and impact time. Results: Within the contact zone of skull and impactor critical stress values could be seen which lay at the lower yield border for potential fractures. A second much lower stress zone was depicted in the anterior-medial orbital roof. Conclusions: In this simulation a fist punch, which could generate distinct fractures in the midface and naso-ethmoid-orbital region, would only reach the limits of a small fracture in the supraorbital region. The reason is seen in the strong bony architecture. Much higher forces are needed to create severe trauma in the upper face which is supported by clinical findings. Finite element analysis is the method of choice to investigate the impact of trauma on the human skeleton.
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19

Kaufmann, Sylvia, and Sylvia Frühwirth-Schnatter. "Bayesian Analysis of Switching ARCH Models." Department of Statistics and Mathematics, WU Vienna University of Economics and Business, 2000. http://epub.wu.ac.at/744/1/document.pdf.

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We consider a time series model with autoregressive conditional heteroskedasticity that is subject to changes in regime. The regimes evolve according to a multistate latent Markov switching process with unknown transition probabilities, and it is the constant in the variance process of the innovations that is subject to regime shifts. The joint estimation of the latent process and all model parameters is performed within a Bayesian framework using the method of Markov Chain Monte Carlo simulation. We perform model selection with respect to the number of states and the number of autoregressive parameters in the variance process using Bayes factors and model likelihoods. To this aim, the model likelihood is estimated by combining the candidate's formula with importance sampling. The usefulness of the sampler is demonstrated by applying it to the dataset previously used by Hamilton and Susmel who investigated models with switching autoregressive conditional heteroskedasticity using maximum likelihood methods. The paper concludes with some issues related to maximum likelihood methods, to classical model select ion, and to potential straightforward extensions of the model presented here. (author's abstract)
Series: Forschungsberichte / Institut für Statistik
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20

Wang, Xin Jun. "Failure criterion for masonry arch bridges." Thesis, University of Dundee, 1993. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318150.

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21

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.

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22

HUAMANI, LUIS ALBERTO NAVARRO. "BAYESIAN INFERENCE ON MULTIVARIATE ARCH MODELS." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2001. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=1868@1.

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CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO
O objetivo deste trabalho é desenvolver uma estratégia Metropolis-Hastings para inferência Bayesiana, usando a estrutura ARCH multivatriada com representação BEKK.Em problemas complexos, como a generalização ARCH/GARCH univariadas para estruturas multivariadas, o processo de inferência é dificultado por causa do número de parâmetros envolvidos e das restrições a que eles estão sujeitos. Neste trabalho desenvolvemos uma estratégia Metropolis- Hastings para inferência Bayesiana, usando uma estrutura ARCH multivariada com representação BEKK.
The objective of this work is to develop Metropolis-Hasting for strategy Bayesian Inference, based on a Multivariate ARCH model with BEKK representation. In complex problems, such as the multivariate generalization of ARCH/GARCH structures, the inference process in complicated, due to the large number of parameters involved and to the restrictions they must satisfy. We propose Metropolis- Hastings structure to provide inference, in a Bayesian framework, for a multivariate ARCH model with BEKK representation.
EL objetivo de este trabajo es desarrollar una estrategia Metropolis-Hastings para inferencia Bayesiana, usando La extructura ARCH multivatriada con representación BEKK.En problemas complejos, como la generalización ARCH/GARCH univariadas para extructuras multivariadas, el proceso de inferencia se hace dificil por causa del número de parámetros involucrados y de las restricciones a que ellos están sujetos. En este trabajo desarrollamos una estrategia Metropolis- Hastings para inferencia Bayesiana, usando una extructura ARCH multivariada con representación BEKK.
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23

Yu, Tzu-Yang (Tzu-Yang Young) 1973. "Behavior of a coupled arch system." Thesis, Massachusetts Institute of Technology, 2002. http://hdl.handle.net/1721.1/84825.

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24

Msaaf, Khaoula. "Multi-Objective optimization of arch bridges." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/111519.

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Thesis: M. Eng., Massachusetts Institute of Technology, Department of Civil and Environmental Engineering, 2017.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 83-84).
Trussed arch bridges are commonly used to attain big spans. They are efficient structures that offer a wide range of geometries, materials, and topologies. This thesis studies the influence of the geometry and topology of arch bridges on both their structural performance relayed by the maximum deflection and their structural weight. Various materials are also considered to calculate the embodied carbon emission and investigate the environmental impact of arch bridges. Gustave Eiffel's Garabit Viaduct is used as a design precedent for this study. 2-D and 3-D parametric models of the arch bridge are realized using Grasshopper [8]. Changing the geometric parameters in addition to the topology enables the investigation of the bridge's performance. The cross sections are automatically optimized in each case. Furthermore, a multi-objective optimization process was run on the bridge to examine the tradeoffs between the deflection and the self-weight. The weight-oriented optimization allows saving more than 60% of the weight compared to the original structure. Analyzing the different resulting designs proves that increasing the depth at the arch's crown and the depth at the base of the arch leads to better deflection results. It also demonstrates that using a denser truss structure leads to a lighter structure.
by Khaoula Msaaf.
M. Eng.
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25

Wu, Lufang. "Serviceability assessments of masonry arch bridges." Thesis, Cardiff University, 2010. http://orca.cf.ac.uk/55010/.

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Masonry arch bridges continue to play an important role in the UK's transport infrastructure, forming a significant proportion of road, rail and waterway crossings. Many of these bridges are relatively old and are still in service in their original configuration. Increasing vehicle loads and speeds have highlighted the need for reliable estimates of both ultimate and serviceability load levels. Most experimental work and assessment methods have so far been carried out under ultimate load. Only limited work has been undertaken to date on serviceability assessment methods, this project therefore aims to develop a systematic method to assess the serviceability load of masonry bridges under a series of different serviceability criteria. A complex spreadsheet was developed as the main analytical tool for the serviceability assessment and was an encastered elastic analysis based on Castigliano's complementary energy method. The geometric data from a large number of real masonry bridges data was gathered and analysed to develop suitable distribution statistics. Three independent serviceability criteria were then developed based on an attempt to replicate, on average, the existing assessment methods. These three criteria are stress, deflection and cracking depth. Finally, a serviceability assessment method system was fully established within the developed spreadsheet.
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Fairfield, Charles Alexander. "Soil-structure interaction in arch bridges." Thesis, University of Edinburgh, 1994. http://hdl.handle.net/1842/13809.

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European Community directives now insist upon the imposition of 11.5t axle weights for the assessment of highway bridges and structures. This need for heavier loads arises from the Community wide harmonisation of transport policy. Its successful implementation requires the urgent assessment of our bridge stock of some 75000 masonry arches. The analysis of arch bridges has long lacked an accurate method of assessing the loads transmitted to the arch ring by the surrounding soil. This thesis proposes pressure distributions suitable for use in the analysis of arch bridges. It examines, by way of instrumented small scale and in-situ tests, the soil-structure interaction effects arising from the backfill material. Observations of zones of soil displacement around a loaded arch are made in order to better describe the interactive effects. A finite element analysis of the instrumented tests was done and a parametric study was used to assess the effects of various material properties upon the system's behaviour. The inclusion of the interactive effects observed, and modelled, intends to lead to cost savings in the arch bridge assessment programme by reducing the conservatism inherent in the most common assessment methods. Design curves incorporating soil-structure interaction effects are presented where significant capacity increases can be seen compared with analyses ignoring the effects.
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Ould, Ahmedou Voffal Mohamed Said. "Estimation récursive dans les modèles Arch." Montpellier 2, 1994. http://www.theses.fr/1994MON20115.

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Le but de cette these est l'etude des proprietes asymptotiques des estimateurs de robbins-monro et des moindres carres d'un modele arch. Elle comprend cinq chapitres. Le premier chapitre rappelle les proprietes de ces modeles et fait une revue bibliographique. Dans le deuxieme chapitre nous determinerons la vitesse de convergence de l'estimateur des moindres carres. Dans les troisieme et quatrieme chapitres nous definissons un estimateur de robbins-monro et montrons sa forte consistance. Dans le chapitre 5 enfin, nous effectuons des simulations de ces estimateurs
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Raiford, William Arthur. "eGaIn Sensor for Plantar Arch Measurement." Thesis, Harvard University, 2015. http://nrs.harvard.edu/urn-3:HUL.InstRepos:17417589.

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An essential part of gait training is providing real-time feedback, which has shown to be effective by allowing runners to identify and correct biomechanical dysfunctions in the leg movement while walking or running. Several types of sensing devices are used to provide measurements for the feedback used in gait training, including pressure sensing treadmills that measure forces exerted by the runner and motion capture systems that track and profile a runner’s motions. For conditions affecting the plantar arch measurements are harder to attain because of the location of the arch during gait. Currently, there are no sensing devices that offer reliable, real-time measurements on plantar arch deformation for runners with plantar arch injuries. This paper describes the design of a sensing device consisting of a soft, stretchy eGaIn strain sensor that can conform to the shape of a runner’s foot and measure the deformation of the plantar arch in real-time for gait training. The measurements from this device were found to correlate with the Arch Height Index, a reliable measurement used to classify arch structure.
Mechanical Engineering
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29

Choden, C. Kezang. "Integer-valued ARCH and GARCH models." OpenSIUC, 2016. https://opensiuc.lib.siu.edu/theses/1990.

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The models for volatility, autoregressive conditional heteroscedastic (ARCH) and generalized autoregressive conditional heteroscedastic (GARCH) are discussed. Stationarity condition and forecasting for simple ARCH(1) and GARCH(1,1) models are given. The model for discrete time series is proposed to be negative binomial integer-valued GARCH model, which is a generalization of the Poisson INGARCH model. The stationarity conditions and the autocorrelation function are given. For parameter estimation, three methodologies are presented with a focus on maximum likelihood approach. Simulation study on a sample size of 100 and 500 are carried out and the results are presented. An application of the model to a real time series with numerical example is given indicating that the proposed methodology performs better than the Poisson and double Poisson model-based methods.
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Enocksson, David, and Joakim Skoog. "Evaluating VaR with the ARCH/GARCH Family." Thesis, Uppsala universitet, Statistiska institutionen, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-168283.

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The aim of the thesis is to identify an appropriate model in forecasting Value-at-Risk on a morevolatile period than that one from which the model is estimated. We estimate 1-day-ahead and10-days-ahead Value-at-Risk on a number of exchange rates. The Value-at-Risk estimates arebased on three models combined with three distributional assumptions of the innovations, andthe evaluations are made with Kupiec's (1995) test for unconditional coverage. The data rangesfrom January 1st 2006 through June 30th 2011. The results suggest that the GARCH(1,1) andGJR-GARCH(1,1) with normally distributed innovations are models adequately capturing theconditional variance in the series.
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Taniai, Hiroyuki. "Inference for the quantiles of ARCH processes." Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210305.

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Ce travail se compose de trois parties consacrées à différents aspects des modèles ARCH (AutoRegressive Conditionally Heteroskedastic) quantiles. Dans ces modèles, l’hétéroscédasticité conditionnelle est à prendre dans un sens très large, et affecte de fa¸ con potentiellement différenciée tous les quantiles conditionnels (et donc la loi conditionnelle elle-même), et non seulement, comme dans les modèles ARCH classiques, l’échelle conditionnelle.

La première partie étudie les problèmes de Value-at-Risk (VaR) dans les séries financières ainsi modélisées. Les approches traditionnelles présentent une caractéristique discutable, que nous relevons, et à laquelle nous apportons une correction fondée sur les lois résiduelles. Nous pensons que les fondements de cette nouvelle approche sont plus solides, et permettent de prendre en compte le fait que le comportement des processus empiriques résiduels (REP) des processus ARCH, contrairement à celui des REP des processus ARMA, continue à dépendre de certains des paramètres du modèle.

La seconde partie approfondit l’étude générale des processus empiriques résiduels (REP) des processus ARCH dans l’optique de la régression quantile (QR) au sens de Koenker et Bassett (Econometrica 1978). La représentation de Bahadur des estimateurs QR, et dont découle la propriété de tension asymptotique des REP, est établie.

Finalement, dans la troisième partie, nous mettons en évidence la nature semi-paramétrique des modèles ARCH quantiles, et l’invariance, sous l’action de certains groupes de transforma-tions, des sous-modèles obtenus en fixant la valeur des paramètres. Cette structure de groupe permet la construction de méthodes d’inférence invariantes qui, dans l’esprit des résultats de Hallin and Werker (Bernoulli 2003) préservent l’optimalité au sens semi-paramétrique. Ces méthodes sont fondées sur les rangs et les signes résiduels. Nous développons en particulier les R-estimateurs des modèles considérés et étudions leurs performances.
Doctorat en Sciences
info:eu-repo/semantics/nonPublished

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32

Lam, Hung H. "Hyperbolic, irregular, spatial and arch time series." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape10/PQDD_0012/NQ42537.pdf.

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33

Callaway, Phillip Arthur. "Soil-structure interaction in masonry arch bridges." Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/3036/.

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Gong, Nai-Guang. "Finite element analysis of masonry arch bridges." Thesis, University of Nottingham, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.335791.

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35

Hodgson, J. A. "The behaviour of skewed masonry arch bridges." Thesis, University of Salford, 1996. http://usir.salford.ac.uk/27332/.

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Masonry arch bridges have been used throughout the world. Many thousands exist in Europe. The number of arch bridges in the United Kingdom has been estimated at 75,000 with approximately equal numbers occurring within the road and railway networks. The arch is very pleasing to the eye. Many arch bridges are listed structures so that replacement schemes are not options. In 1880 Baker was commissioned to report on the deterioration of Telford's Bridge at Over. Baker wrote, "The abutments had gradually gone over, and had been continuing to go over for sixty years. The result was that certain barbarians were actually urging the magistrates to take down the bridge...". He continued, "... cracks in the spandrels were big enough to walk through quite comfortably. It would be a disgrace to the country if they pulled down Telford's historical work and substituted a hideous iron latticebridge", (Heyman & Threlfall, 1973). Masonry arch bridges were built to carry a road, a railway or sometimes a waterway over an obstacle. A right arch bridge was used where the crossing could be perpendicular to the obstacle. In contrast, a skewed arch was built wherever the obstacle and over-road intersected at any angle other than 90°. Thus, a right arch is a special case of the more general class of skewed arch. The extent of existing knowledge of the behaviour of arch bridges is limited to the right arch in which many effects have either been omitted or have been simplified. These effects include the spandrel walls, the backfill, irregular geometry, and eccentric loading. Clearly, there is scope for an advancement of knowledge so that these effects may be considered and ultimately the behaviour of the skewed arch bridge can be described. The construction of arch bridges in Great Britain reached its zenith at around the beginning of the Nineteenth century. At this time, if conditions prevailed, there was a general desire for each new bridge to exceed the span of any that had gone before (Ruddock, 1979). However, Sejourne (1913) could only find eight structures in the United Kingdom that had at least one span with a clear opening of more than 40.0 m.
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36

Colla, Camilla. "Non-destructive testing of masonry arch bridges." Thesis, University of Edinburgh, 1997. http://hdl.handle.net/1842/12165.

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Stone masonry arch bridges form a critical part of the transportation system. Present methods of assessment are sometimes too conservative and a number of bridges fail the assessment even though they appear in good condition. Non-Destructive Testing can play a key role and three Non-Destructive techniques - radar, sonics and conductivity measurements- are proposed for bridge testing with the aim of obtaining structural dimensions, material characteristics and integrity information which would lead to a more accurate assessment of the structural conditions being made. After discussing problems and limitations with current analytical and load testing methods of assessment, a review of archetypal forms of bridge construction methods employed along the centuries ismade, showing that a greater variety of bridges than commonly believed, exists. The review also enables an Engineer to have some indication of construction type relating to the area, era and designer. The work then includes site work on two masonry bridges and laboratory experiments. On site, the three Non-Destructive Techniques mentioned were used for testing two Scottish stone masonry bridges (one with a brick arch ring) with the aim of obtaining information about the condition and nature of the materials in the fill, the internal configuration of the structure and the geometrical dimensions of the elements. Data from each technique were plotted in the form of cross-sectional tomographic maps and the results interpreted and compared. Limitations are also discussed. In the laboratory, experiments with radar were undertaken to calibrate the technique in controlled conditions and also, and more importantly, to obtain information about phenomena of signal behaviour and material properties as would be found in a masonry arch bridge. The findings served the purpose of aiding a better planning of radar surveys to be made and an improved understanding and interpretation of the radar data to be obtained.
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Robinson, Justin. "Analysis and assessment of masonry arch bridges." Thesis, University of Edinburgh, 2000. http://hdl.handle.net/1842/12876.

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The importance of masonry arch bridges to the transport infrastructure throughout Europe is unquestionable. However with the ever increasing axle loads present on today's roads, and new European directives increasing the required load carrying capacity, the need for an accurate and reliable method of arch bridge assessment has never been more important. The current methods of arch bridge assessment have been shown to be conservative resulting in unnecessary and costly repair work or replacement of structures. The research described in this thesis is an element of an on-going study into soil-structure interaction, a very important factor for the accurate assessment of arch bridges. This overall investigation, continuing study into the effects of soil-structure interaction, is undertaken with a variety of methods and techniques. These include model bridge testing investigating different load types and fill heights, monitoring of full scale structures and subsequent analysis investigating thermal effects, comparison of the present arch bridge assessment methods linked with an actual arch bridge assessment program and the development of new numerical modelling models of arch assessment. Thus an investigation using discrete element analysis methods has been conducted, with comparison with finite element methods and physical models.
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Zhang, Yanyang. "Advanced nonlinear analysis of masonry arch bridges." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/29128.

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This research investigates the nonlinear response up to collapse of masonry arches and arch bridges using advanced numerical descriptions. Past research has shown that the mesoscale modelling approach for brick-masonry, where bricks and mortar joints are modelled separately, may offer a realistic representation of the mechanical behaviour of masonry components. However, because of the significant computational cost, thus far the use of this modelling strategy has been mainly restricted to 2D analysis of masonry arches and arch bridges. In some cases this may lead to a crude representation of the response which is inherently three-dimensional, especially when the analysed structure is subjected to eccentric loading or is characterised by a complex geometry (e.g. skew arches). In this work, masonry arches and arch bridges are analysed using a partitioned mesoscale approach, which enables the use of a detailed model for describing material nonlinearity at structural scale. This is combined with a partitioned approach allowing for parallel computation which guarantees computational efficiency. In the 3D mesoscale description, brick units and mortar interfaces are modelled separately accounting for the actual texture and arrangement of masonry. 3D elastic continuum solid elements are used to model brick units while mortar interfaces are modelled by means of 2D nonlinear interface elements. In analysing masonry bridges, the backfill material is modelled as an elasto-plastic continuum, while the physical interface between the continuum and mesoscale domain for masonry is represented by nonlinear zero-thickness interface elements allowing separation and plastic sliding. The proposed modelling approach has been applied to the analysis of multi-ring square and skew arches and masonry arch bridges. The numerical results, which also include numerical-experimental comparisons, confirm the accuracy of the adopted numerical strategy. Moreover numerical simulations have been performed to investigate the effects of the arch geometry, loading positions, material characteristics and potential settlements at the supports. The results obtained offer important information and a detailed description on the complex response of these critical structural systems under different loading and boundary conditions.
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Noruziaan, Bahman Carleton University Dissertation Engineering Civil and Environmental. "Nonlinear seismic analysis of concrete arch dams." Ottawa, 1995.

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40

Dineen, Michael. "Mandibular Arch Width Stability With Begg Treatment." Thesis, Faculty of Dentistry, 1988. http://hdl.handle.net/2123/5095.

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41

Raan, F. J. du. "Using a mathematical model to determine dental arch- perimeter in class ii patients presenting at UWC orthodontic clinics." University of the Western Cape, 2021. http://hdl.handle.net/11394/7976.

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Doctor Scientiae - DSc
Determining arch perimeter is of importance in both a clinical setting, where it is used to determine space requirements, as well as in an epidemiological setting where it is used to describe large populations. Physical measurement of arch perimeter is time consuming and may be prone to operator errors when done on study casts and even more so in a clinical situation. The use of a simple mathematical model to predict arch perimeter, using a few measurements that can be done easily and reliably, would be of great use to the practitioner.
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42

PIGAZZINI, ILARIA. "Evaluating and Detecting Architecture Erosion." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2022. http://hdl.handle.net/10281/365009.

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Un'architettura software è erosa (o degradata) se mostra una progressiva perdita di integrità strutturale a causa di violazioni dei principi di progettazione. I sistemi erosi soffrono di Architectural Technical Debt (ATD), lo sforzo aggiuntivo richiesto agli sviluppatori per gestire i difetti causati dall'erosione. Un sintomo dell'accumulo di ATD è la presenza di Architectural Smells (AS), decisioni di software design che hanno un impatto negativo sulla qualità interna del sistema software. I sistemi affetti da AS soffrono di maggiori costi di manutenzione e sono più difficili da evolvere. Questa tesi indaga sei diversi tipi di AS che violano diversi principi di design in progetti Java monolitici Open-Source e industriali. Identifichiamo gli AS con il nostro strumento, Arcan, e introduciamo la sua nuova estensione per la rappresentazione dei software concerns. Discutiamo poi gli AS dal punto di vista dei professionisti, cercando di riassumere come gli AS sono percepiti e validando i risultati di Arcan. Riportiamo anche i risultati dei nostri studi empirici riguardanti l'evoluzione e la correlazione di AS e ATD. Infine, presentiamo i nostri primi risultati riguardanti la migrazione e la manutenzione di architetture a microservizi, con particolare attenzione al rilevamento degli odori dei microservizi.
A software architecture is eroded (or degraded) if it shows a progressive loss of structural integrity due to design principle violations which leads to the deviation of the implemented architecture from the intended architecture. Eroded systems suffer from Architectural Technical Debt (ATD), the additional effort required by developers to manage the shortcomings caused by the erosion. A symptom of the accumulation of ATD is the presence of Architectural Smells (AS), design decisions that impact negatively on the internal system quality. Systems affected by AS suffer from higher maintenance costs and are harder to evolve. This thesis investigates six different types of AS violating different design principles in Open-Source and industrial monolithic Java projects. We identify AS with our tool, Arcan, and introduce its new extension for the representation of software concerns. We then discuss AS from the point of view of practitioners, trying to summarise how AS are perceived and validating Arcan results. We also report the results of our empirical studies concerning AS and ATD evolution and correlation. Finally, we present our first results concerning the migration and maintenance of microservices architectures, with a focus on the detection of microservices smells.
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43

Weaver, Kolin E. "The stability of the WALA ridge as a landmark for determining dental archform." Morgantown, W. Va. : [West Virginia University Libraries], 2010. http://hdl.handle.net/10450/10936.

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Thesis (M.S.)--West Virginia University, 2010.
Title from document title page. Document formatted into pages; contains x, 107 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 87-96).
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44

Jeantheau, Thierry. "Modèles autorégressifs à erreur conditionnellement hétéroscédastique." Paris 7, 1993. http://www.theses.fr/1993PA077169.

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Depuis l'article fondateur de Engle en 1982, les modèles dynamiques hétéro scédastiques ont connu des développements importants; le but de cette thèse est d'étudier les propriétés de ce type de modèles. Dans une première partie, on définit un modèle hétéro scedastique assez général, et on montre alors sous quelles conditions les estimateurs du minimum de contraste sont fortement consistants. Le théorème donné dans ce chapitre permet de faire des hypothèses très faibles sur l'existence de moments du processus solution. Dans la deuxième partie, ce résultat est applique à un modèle auto régressif à erreur Garch. Les conditions de stationnarité et d'identifiabilité du modèle sont étudiées en détail. On montre alors que tous les modèles stationnaires au sens strict peuvent être estimés de façon fortement consistante. Dans la troisième partie, on montre comment ces résultats peuvent être étendus au cadre multivarié. On prend alors comme exemple le modèle Garch multivarié à corrélation constante. Enfin, les quatrième et cinquième parties traitent des applications sur des données simulées (où les résultats obtenus confirment nos résultats théoriques) et sur des données financières réelles (principalement sur des cours de change)
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Лисовенко, А. В., Дмитро Володимирович Лісовенко, Дмитрий Владимирович Лисовенко, and Dmytro Volodymyrovych Lisovenko. "Анализ величин и направления опорных реакций в трехшарнирной статически определимой арки." Thesis, Сумский государственный университет, 2015. http://essuir.sumdu.edu.ua/handle/123456789/39906.

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46

Загорулько, Андрій Васильович, Андрей Васильевич Загорулько, Andrii Vasylovych Zahorulko, and Е. И. Алтынцев. "Численный расчет и анализ напряженно-деформированного состояния арки при различных способах её нагружения." Thesis, Изд-во СумГУ, 2004. http://essuir.sumdu.edu.ua/handle/123456789/23438.

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47

Zatout, Ali. "Approche bivariée des processus ARCH : application à la couverture à terme optimale du café et cacao." Montpellier 1, 1994. http://www.theses.fr/1994MON10033.

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Les processus de variance conditionnelle arch sont presentes dans le but d'appliquer la methodologie d'engle (1982) aux marches a terme du cafe et du cacao. La nature, les consequences et les tests d'heteroscedasticite sont evoques afin de motiver l'introduction des modeles arch comme une specification parametrique simple de l'heteroscedasticite. Une premiere application consiste en une estimation de modeles garch univaries des prix au comptant et a terme du cafe et du cacao. La specification explique assez bien la variation temporelle de la matrice de variances et covariances conditionnelles. Toute fois, les informations degagees du modele univarie sont partielles et ne permettent pas de prendre en compte la dynalmique interne des deux produits de base. La seconde applicationporte sur l'estimation d'un modele garch bivarie des memes prix et applique le resultat pour estimer le taux de couverture (hedge) a terme, qui joue un role strategique dans le negoce sur les marches des produits de base. On montre que la specification garch est efficace pour la connaissance des distributions de ces prix et qu'ils menent vers une description naturelle de la variation dans le temps du taux de couverture (hedge) des marches a terme des produits de base
The methodologie of the arch (engle 1982) process is introduit in order to applied to the futures markets of coffee and cocoa. The distribution of commodity (coffee and cocoa) cash and futures prices are investigate and applies the results to estimate the optimal hedge ratio (ohr). Commodity prices movements are modelled using the generalized autoregressive conditional heteroskedastic (garch). Bivariate garch models of cash and futures prices are estimted for the same two commodities. The optimal hedge ratio is then calculated as a ratio of the conditional covariance between cash and futures to the conditional of variance of futures. The estimated ohrs reveal that the standard assumption of a time-invariant ohr is inappropriate
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48

Pornratanavisai, Jarunard. "Dental arch changes over a 27-year period /." [St. Lucia, Qld.], 2003. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe16979.pdf.

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49

Miri, Mahmoud. "Modelling of repair techniques for masonry arch bridges." Thesis, Cardiff University, 2005. http://orca.cf.ac.uk/55998/.

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Small scale centrifuge models were used to study the behaviour of arches repaired using different techniques. The models under test were 1/12th scale replicas of a 6 metre single span three ring arch. Two types of arch geometry, with span/rise of 4 and 2, were studied as a shallow and deep arch geometry. The models were tested in a centrifuge under a steady equivalent gravity of 12g. Two types of 2-D and 3-D arch models were studied which had the same geometry but different in the addition of spandrel walls. The 3-D models were built with spandrel walls but without any wing walls or parapet. Both 2-D and 3-D arch models were tested under rolling and failure loads. The models were usually tested with fourteen passes of a rolling load and then up to the observation of first signs of failure to enable them to be suitable for applying a repair method. The repaired models were tested using the same procedure but up to the full failure load. To understand the behaviour of the arch models under unsymmetrical loads different roller weights were applied at different positions. The arch deflection and the soil/masonry interaction in arch extrados were measured in all the tests and compared with each other. Plastic mesh reinforcement, stitching, and concrete slab on top of the soil backfill were applied as repair methods to the 2-D arch models. A review of the results has shown an increase in arch stiffness, decrease in deflections and a significant improvement in the ultimate load carrying capacity. A significant effect on the pressure distribution on the arch barrel was observed due to the application of the concrete slab on top of the backfill. Stitching of arch barrel and the barrel to the spandrels, applying partial saddle concrete and strengthening of spandrel wall using reinforced concrete were tested in the 3-D arch models. The results showed improvements in the stiffness and ultimate arch load carrying capacity due to these repair techniques. The results provide a valuable data base for validation of numerical models and an initial attempt to use them with a commercial finite element program is included.
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Bourke, John David. "Behaviour and analysis of a flexible concrete arch." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.600123.

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The development of steel reinforced concrete in the early 20th century led to a decline in masonry arch bridge building. Traditional masonry arch construction is time consuming and involves considerable form work usually in the form of timber centring, as well as traditional skills. As a result, reinforced concrete arches and slab and beam bridges became common. However, durability issues associated with corrosion of steel have become a major and costly problem and design can now favour steel-free structures. The FlexiArch bridge system is a sustainable alternative for short span crossings and contains no steel reinforcement or mortar joints. This thesis presents detailed research into the behaviour and analysis of FlexiArch systems through laboratory models and non-linear finite element analysis. The arches were monitored through lifting, arch ring tests, backfilling, and under full test loading. The variables in the eight arches were the backfill type, arch ring thickness, solid and hollowcore voussoir design, and span to rise ratio. The experimental investigation demonstrated that higher peaks loads were achieved in the arches of higher arch ring thickness; the rings with so lid voussoirs sustained higher loads than rings with hollowcore voussoirs, and doubling the arch span (shallower profile) typically halved the peak load. The importance of accurate material properties for use in numerical prediction was highlighted in the literature and control tests were carried out to determine the material properties. The nonlinear finite element analysis investigated three areas. Firstly, models were constructed to replicate those tested in the laboratory and to further compare key variables. Secondly. a detailed parametric study in material properties demonstrated that many of the parameters had a linear relationship with the arch predicted peak load. Finally the NLFEA model was validated through modelling four arch bridges presented in the literature and predicted accurate behaviour when compared to tests.
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