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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
71

Rectification of 2-D to 3-D Finite Element Analysis in Buried Concrete Arches Under Discrete Loading

Aagard, Adam D. 21 March 2007 (has links) (PDF)
Construction of tunnels and small- to medium-span bridges is a $12 billion per year industry in the United States, with a significant portion going into buried arch structures. Notwithstanding such expenditure, modern arch design and construction, in many cases, is highly conservative. This is because the closed-form solutions used by most designers today do not correctly account for soil-structure interaction. In fact, soil-structure interaction makes a closed form solution impossible. With the advent of high power computers in recent years, some designers have turned to finite element (FE)modeling as the main vehicle of analysis. Such numerical procedures provide an accurate approximation of physical behavior. Practices using FE analysis for buried arch design almost exclusively use two-dimensional models because they are faster to set up and analyze than three-dimensional models and cost substantially less. However, 2-D models fail to account for the stiffness of the structure and spread of discrete loads in the third-dimension. Both the 1996 and 1998 AASHTO-LRFD Bridge Design Specifications address this problem, providing methods of load reduction. Much of the current reduction, however, is based on research done on concrete bridge decks, and does not account for continuous elastic support or the geometry of the structure. This results in a conservative analysis at low fill covers (<10') and/or increasing spans (>20’). This research provides a method to rectify the discrepancy that arises in discrete loading of 2-D FE models of semi-flexible buried concrete arch bridge, culvert, and tunnel systems due to the plane-strain assumption. Rectification is accomplished by providing a correlation between the deflection of a beam-on-elastic-foundation analysis and a distribution length by which the load in 2-D analysis is reduced. Distribution lengths are derived using bending energy ratios. The correlation considers structural geometry, overburden height, and base soil stiffness. Reduction of the 2-D design load by the proposed distribution length results in shear forces and bending moments nearly equivalent to those obtained from 3-D analysis in the plane of discrete load application transverse to the structure. Less conservative results are also obtained for axial forces. These results are intended for use on structures that are four times the span in length, or longer.
72

Numerická analýza přesypávaných mostních konstrukcí / Numerical analysis of culvert

Krtek, Jiří January 2014 (has links)
The topic of this Thesis is a study of the behavior of flexible metal large-span culverts during the construction and the operation. The aim is to analyze the behavior of the structure as a result of an unequally dropping support and a position of the load to the construction in relation to the soil cover height above the top of the steel construction. The Thesis is theoretical and based on the numerical parametric study.
73

Návrh vodohospodářských opatření v katastrálním území / Proposal of Water Management Measures in the Cadastral Area

Prokop, Pavel January 2019 (has links)
This diploma thesis is divided into two main parts. The first part describes issues of the proposal of water management measures in land consolidation process. Second part deals with the conceptual proposal of water management measures in the specific cadastral area. This part also include graphic attachments.
74

Protipovodňová ochrana Hustopeče nad Bečvou / Flood protection of Hustopeče nad Bečvou

Jauernig, Jan January 2016 (has links)
This thesis deals with flood protection of the Hustopeče nad Bečvou. The work is divided into three parts. The first part describes the data necessary for the design of flood protection measures. The second part describes the hydrotechnical calculations and the third part describes proposals for flood protection.
75

Static analysis of soil-steel composite bridges in sloping terrain

Skrobic, Karina, Bergström, Josefine January 2014 (has links)
Soil-steel composite bridges are for many reasons very favorable bridges to build. Up to a certain span length they are economical, practical to transport and simple and quick to build. Especially in remote places, with unfavorable sloping terrain, this can be of great interest when the transport of material can be difficult and costly. The swedish manual for design of soil steel composite bridges was presented by Lars Pettersson and Håkan Sundquist in the year 2000. It is today used in Sweden and other neighboring countries as the main manual for the design of soil-steel composite bridges. The design manual is however only valid for longitudinal slopes up to 10%, which is low in comparison to natural sloping hillsides. The purpose of this thesis is to study the structural behavior of soil steel composite bridges in sloping terrain, with the use of the finite element software PLAXIS 2D. Two case studies of one low arch culvert bridge and one pipe arch culvert are studied and later modeled in PLAXIS. The two case studies does not have sloping terrain, but are used to assure that the FEM-models behaves correctly during the backfilling process in PLAXIS. The analysis studies the change in sectional forces in the bridges during an increase inslope above the structures. The values from the FEM-models are compared to field measurements from the case studies, as well as to values calculated in accordance to the swedish design manual. This is done to see how well the different approaches compare to each other, and, since the design manual does not consider slopes exceeding 10%, it is interesting to investigate if the SDM-calculated values still appear valid for slopes larger than 10%. In addition to sectional forces, the slope stability of the FEM-models is also evaluated and compared to analytical values calculated using the ordinary method of slices. This slope stability study focuses on if the bridges affect the slope stability safety factor. The thesis also investigates if these bridges are more sensitive to increasing slopes from a slope stability or sectional forces point of view. I.e if the slope inclination magnitude will be determined based on the sectional forces in the structure or the slope stability of the soil surrounding the structure. The criteria that are researched to come to this conclusion are for example the slope stability safety factor, or the possible yielding of the culvert wall due to too large sectional forces in the structure. The results show that for low cover depths, the slope stability safety factor decreases slightly when a structure is introduced to the slope. For larger cover depths, read 3 meters or more, the slope stability seems unaffectedby the structure. The results also shows that the sectional forces in the structures compares well to both measured and calculated values for slope inclinations up to 30% for rather small cover depths, i.e 1 meter. For slopes larger than 30% the sectional forces grows and no longer reflect the measured and calculated values. However, since only two case studies are performed, these conclusions might not be valid for different profile shapes. Additionally there are indications that the low arch bridge is more sensitive to slopes than the pipearch culvert. / Rörbroar, eller “soil-steel composite bridges”, är av många anledningar fördelaktiga att bygga. Upp till en viss spännvidd är de ekonomiska, praktiska att transportera samt enkla och snabba att konstruera. Särskilt vid vissa svåråtkomliga platser, med ofördelaktigt sluttande terräng, kan det vara av stort intresse när materialtransport annars kan vara både komplicerat och kostsamt. Den svenska manualen för dimensionering av rörbroar presenterades av Lars Pettersson och Håkan Sundquiståret 2000. Manualen används idag i Sverige samt angränsande länder som den huvudsakliga dimensioneringsmanualen för rörbroar. Dock är den svenska manualen enbart giltig för lutningar upp till 10%, vilket ären låg lutning i jämförese med många naturliga sluttningar. Syftet för detta arbete är att studera det statiska beteendet hos kringfyllda rörbroar i lutande terräng,med hjälp av det finita element programmet PLAXIS 2D. Två fallstudier av dels en låg bågbro, dels en sluten kulvertbro, studeras och modelleras senare i PLAXIS. De två fallstudierna har inte sluttande terräng, men används för att säkerställa att FEM-modellerna beter sig korrekt under återfyllnadsfasen I PLAXIS. Analysen studerar förändringen av tvärsnittskrafter i broarna när sluttningen de belastas av ökar. Värdena från FEM-modellerna jämförs mot mätdata från fallstudierna, samt mot värden beräknade enligt den svenska manualen. Detta utförs för att se hur väl de olika metoderna överensstämmer med varandra, och, eftersom dimensioneringsmanualen inte tar hänsyn till lutningar överstigande 10%, är det intressant att se om deSDM-beräknade värdena fortfarande gäller för lutningar större än 10%. Utöver tvärsnittskrafter utvärderas släntstabiliteten hos FEM-modellerna, och dessa resultat jämförs sen mot analytiska värden beräknade enligt lamellmetoden, eller “the ordinary method of slices”. Släntstabilitetsstudien fokuserar på hur broarna påverkar säkerhetsfaktorn för släntstabilitet. Avhandlingen undersöker även om dessa broar är mer känsliga för ökande lutningar från en släntstabilitets- eller tvärsnittskrafts-synvinkel, dvs. om lutningens största storlek kommer att avgöras baserat på de tvärsnittskrafter som uppstår i konstruktionen eller på släntstabiliteten i marken runt konstruktionen. För att bilda oss en uppfattning om detta jämförs exempelvis säkerhetsfaktorn för släntabilitet mot ett eventuellt brott i stålprofilen orsakat av för stora tvärsnittskrafter i konstruktionen. Resultaten visar att säkerhetsfaktorn för släntstabilitet, vid liten överfyllnadshöjd över hjässan, minskar något när en bro byggs i en sluttning. För större överfyllnadshöjder, läs 3 meter och högre, verkar släntstabiliteten vara oförändrad vid introducering av en bro. Resultaten visar även att tvärsnittskrafterna i konstruktionerna överensstämmer bra både mot mätdata samt beräknade värden, för lutningar upp till 30% och små överfyllnadshöjder på exampelvis 1 meter. För lutningar större än 30% växer tvärsnittskrafterna och är inte längre jämförbara mot varken mätdata eller beräknade värden. Dock bör det tilläggas att eftersom endast två fall har studerats utförs så behöver dessa slutsatser inte gälla för andra profiltyper. Utöver detta finns indikationer på att den låga rörbron är mer känslig för en ökning i släntlutning i jämförelse mot denandra bron när det gäller tvärsnittskrafter.
76

Soil Steel Composite Bridges for High-Speed Railways : 2D FEM analysis of the Björnbo Bridge

Woll, Joakim January 2014 (has links)
This research aims to analyse the dynamic behaviour of Soil-Steel Composite Bridges when subjected by high-speed trains. the analyses of the dynamic response for these structures are needed since there is little research performed in the present field of knowledge. Since there is also in need to perform separate dynamic analysis for these structures to verify their dynamic response, the dynamic behaviour must be analysed. The research are performed in 2D FE-models in the commercial FE-program Brigade/PLUS since there is of interest to analyse if simplified 2D-models can predict the dynamic behaviour for these structures and verify against design criterions in regulatory documents. The research is performed by calibrating a reference model against collected field measurements from a constructed Soil-Steel Composite Bridge, SSCB, located in Märsta, Sweden, Märsta Bridge. The calibration process was made to ensure satisfactory results before continuing the research by analysing a future planned SSCB in a case study that is known to in the future be subjected by high-speed trains. The future planned bridge is the Björnbo Bridge located in Skutskär, Sweden. A static structural design is first made with existing methods to verify Björnbo Bridge for static load cases. Attempts is made to verify the Björnbo Bridge against dynamic criterions available in Eurocode documents and Swedish Transport Administration regulatory documents, which includes verifying accelerations limits for 10 different high-speed trains. Smaller analysis of fatigue for the Märsta Bridge and the Björnbo Bridge was also made to verify dynamic stresses from giving fatigue damages. Since the research is limited for SSCB for dynamic cases, parametric studies are performed for certain parameters identified from an international literature review of earlier studies in both static and dynamic analysis. The studied parameters are: Soil cover depth, Young's modulus for engineered backfill and different profiles impact. These parametric studies are made to be able to understand influence and sensitivities from the analysed parameters with the long-term goal to develop analysis methods and verifications for SSCB for dynamic load situations. The calibrated reference model showed that there are difficulties in calibrating acceleration levels that agrees with the field measurements from Märsta Bridge. The expected result from the analysis of the Björnbo bridge was to fulfil static structural design criterions and that the acceleration limits were below serviceability criterions for dynamic analysis according to Eurocode documents. Moreover, that the stresses did not give fatigue damages. From parametric studies, it has shown that the governing parameter is the Young's modulus for engineered backfill, which affects estimated accelerations in a fashion that was not expected in the beginning. The presumption to perform dynamic analysis with 2D FE-models has shown that all aspects that is needed to verify cannot be performed, such as bending in two directions or twisting mode shapes. Thus, there is in need to find ways to perform dynamic analysis for SSCB with efficient 3D-models. / Denna avhandling syftar till att undersöka det dynamiska beteendet hos rörbroar när dem belastas med höghastighetståg. Analyser av den dynamiska responsen för dessa konstruktioner är behövlig då det finns lite forskning som utförts inom kunskapsområdet. Då man även behöver genomföra separata dynamiska analyser för dessa konstruktioner för att verifiera  deras dynamiska beteende, så är det ett behov av att dess dynamiska beteende analyseras. Undersökningen är genomförd med FE-modeller i 2D i det kommersiella FE-programmet Brigade/PLUS då det är av intresse att analysera om förenklade 2D-modeller kan forutse det dynamiska beteendet för dessa konstruktioner och verifiera konstruktionen mot kriterier ställda i styrande dokument. Undersökningen genomförs genom att kalibrera en referens modell mot insamlade fältmätningar från en konstruerad rörbro i Märsta, Sverige, Märsta rörbro. Kalibreringsprocessen genomförs för att försäkra att godtagbara resultat erhålls innan undersökningen fortsätter med att analysera en planerad rörbro i en fallstudie som kommer belastas av höghastighetståg. Den planerade rörbron är Björnbo rörbro som skall konstrueras i Skutskär, Sverige. En statisk konstruktionsberäkning med befintliga metoder är först utförd för att erhålla dimensioner och verifiera Björnbo rörbro för ett statiskt lastfall. Därefter utförs försök att verifiera Björnbo rörbro mot dynamiska villkor tillgängliga i Eurokod och Trafikverkets styrande dokument, detta inkluderar att verifiera accelerationsnivåer för 10 olika höghastighetståg. Mindre analyser genomförs även för utmattning för Märsta rörbro och Björnbo rörbro för att verifiera den dynamiska spänningshistoriken inte orsakar utmattningsskador. Då forskningen är begränsad gällande dynamiska studier för rörbroar, så utförs även parametriska studier för parametrar identifierade från en internationell litteraturinventering av tidigare studerade fall för rörbroar gällande både statiska och dynamiska analyser. Dom studerade parametrarna är: Överfyllnadshöjd, Jordmodul för kringfyllning och olika profilers inverkan. Dessa parametriska studier är utförda för att förstå influensen och känsligheten i dessa parametrar med det långsiktiga målet att utveckla analysmetoder för att verifiera rörbroar även för dynamiska situationer. Den kalibrerade modellen visade att det var svårigheter att kalibrera in accelerationsnivåer som överensstämde med fältmätningar från Märsta rörbro. Det förväntade resultatet från Björnbo rörbro var att uppfylla statiska konstruktionsvillkor och att uppfylla accelerationskrav för bruksgränstillståndet för konstruktionen. Samt att kunna verifiera att utmattningen inte skulle utgöra ett problem. Från dom parametriska studierna så har det visat att den styrande parametern är jordmodulen för kringfyllningen, den påverkar accelerationsnivåer som inte var förväntat vid undersökningens påbörjan. Antagandet att utföra de dynamiska analyserna med 2D FE-modeller har visat att alla aspekter som ska verifierasinte kan utföras, så som böjande moment i två riktningar eller vridande mod former. Således, så finns ett behov av att finna vägar att utföra dynamiska analyser för rörbroar i effektiva 3D-modeller
77

Vyhledávací studie obchvatu města Hustopeče / Researching study of by-pass road of city Hustopeče

Tomešek, Zdeněk January 2012 (has links)
This graduation thesis deals about researching study of by-pass road of city Hustopeče, district of Břeclav, Southmoravian region. This city passes main road number 425, which should be connected with the by-pass road. The by-pass road will be designed as road of category S9,5/70 and will be situated west of the city. Terrain is undulated and composed of agricultural parcels. The main purpose of this by-pass road is significant burden of region traffic.
78

Water surface profile modelling for Pinjarra flood diversion channel and economic evaluation

Khalil, Kamal January 2007 (has links)
Shire of Murray has concerns regarding the negative impact that a 100 year flood could have on existing structures built before 1997. The increase cost in construction due to landfill has an adverse effect on development in Pinjarra. Feasibility of constructing a diversion channel at upstream of Murray River to attenuate the flood level from 1 in 100 year ARI to 1 in 50 year ARI, was investigated by Kiong (2003). The Murray River Water Surface Profile along three kilometres south of Greenlands Road was modelled. Flood damages on each flood occurrence were assessed and Average Annual Damage (AAD) was calculated. The AAD is used to estimate the monetary benefit against the construction cost of the diversion channel. Groundwater along Greenlands and Fauntleroy Drains was also modelled to determine the viable depth of the designed channel, as well as the analysis of backwater. The proposed channel is designed at different scenarios (invert level at breakout point, culvert or causeway design, and diversion channel variations). The benefit cost ratio of the proposed diversion channel is calculated. Other mitigation options are suggested including detention basins for structural measure, or building a new flood-proof township for non-structural measure.
79

Konstrukční návrh výukového hydraulického okruhu / Construction design of instructional hydraulic laboratory circuit

Havlát, Michal January 2015 (has links)
It is suitable to add practical illustrations of hydraulic tasks during teaching hydraulics and hydrology. These practical illustrations can be realized by mobile hydraulic circuit which is situated in the auditorium. This thesis is focused on constructional and project solution of the circuit which consists of a compensatory tank with sufficient capacity, pump aggregate and hydraulic measure flume. The construction of hydraulic flume must enable quick, simple and safety installation of a scaled down models of a hydro technical structures. The main requirements of a mobile teaching circuit are clearness of practical hydraulic illustrations, compact dimensions, comparatively low weight, mobility and simple control and manipulation. This diploma thesis also includes design of a scaled down models of a hydro technical structures, especially set of plate weirs, bed-crested weir, ogee-crested weir, culvert, Venturi flume, sluice and radial gate, pier and roughened bed. The hydraulic circuit drawing part also includes instrument carrier with level gauge. This diploma thesis includes theoretical text part, technical report of designed objects, hydraulic calculations and drawing part.
80

Movimentação de duas espécies de Loricariidae através de bueiro em riacho neotropical: desempenho na passagem e comportamento diário / Movement of two species of Loricariidae through culvert in Neotropical stream: performance in the passage and daily behavior

Celestino, Leandro Fernandes 30 July 2013 (has links)
Made available in DSpace on 2017-07-10T18:13:15Z (GMT). No. of bitstreams: 1 Leandro Fernandes Celestino.pdf: 1058585 bytes, checksum: 6108a51713f47912287f5185adf3ae6a (MD5) Previous issue date: 2013-07-30 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The neotropical streams have a rich and important ichthyofauna, nevertheless, in many of these streams there are culverts in his course from the construction of highways. These culverts have the potential to enable the free passage of fish and even restrict the movements, especially upstream. The aim of this study was to evaluate the movement of two Loricariidae species, Ancistrus sp. and Hypostomus acistroides, with the RFID system in a Neotropical stream with a culvert in his course. The passage performance of these species and the daily behavior of the movements on culverts were compared. The results indicated possible difficulty in accessing the culvert: Hypostomus ancistroides has apparently most successful upstream movements relative to Ancistrus sp., demonstrating that besides the low levels of transposition, the culvert can still be a selective barrier to movement. The two species showed greater nocturnal activity, nevertheless, their behaviors differ between periods: the highest activity to Ancistrus sp. occurred dawn (0:00 to 5:59) and to Hypostomus ancistroides the movements were more intense at night (18:00 to 23:59) indicating possible temporal segregation of behavior. / Os riachos neotropicais apresentam uma rica e importante ictiofauna, no entanto, em muitos destes riachos encontram-se bueiros em seu curso, provenientes da construção de estradas de rodagem. Esses bueiros possuem o potencial de permitir a livre passagem dos peixes como também podem restringir os movimentos, principalmente ascendentes. O objetivo deste estudo foi avaliar a movimentação de duas espécies de loricariídeos, Ancistrus sp. e Hypostomus acistroides com o sistema RFID, em um riacho Neotropical com um bueiro em seu curso. O desempenho na passagem destas espécies pelo bueiro e o comportamento diário de movimentos foram comparados. Os resultados indicam possíveis dificuldades de acesso ao bueiro: Hypostomus ancistroides aparentemente possui maior sucesso de movimentações ascendentes em relação à Ancistrus sp., demonstrando que além dos baixos índices de transposição, o bueiro ainda possa ser uma barreira seletiva a movimentação. As duas espécies apresentaram maior atividade noturna, no entanto, seus comportamentos diferiram entre os períodos: para Ancistrus sp. a maior atividade ocorreu de madrugada (00:00-05:59) e para Hypostomus ancistroides os movimentos foram mais intensos a noite (18:00-23:59), o que indica possível segregação temporal de comportamento.

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