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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.
111

Stanovení hydrodynamického zatížení přelévané mostovky s využitím numerických simulací / Determination of hydrodynamic load acting on overflowed bridge deck using numerical simulations

Stoklas, Jan Unknown Date (has links)
The subjekt of this diploma thesis is a quantification of hydrodynamic load of the overflow bridge deck using numerical simulations. The simulation was performe for eight different discharges, which correspond to different degrees of inundation of the bridge deck using different turbulent models in Flow-3D software. The result of the calculation are the values of the hydrodynamic load– the horizontal force, the vertical force and the moment acting on the bridge deck. Furthermore, drag coefficient, lift coefficient and moment coefficient were quantified. Finally, the results of turbulent models were compared with each other and with result of physical experimental testing.
112

Vibration mitigation of high-speed railway bridges : Application of fluid viscous dampers

Tell, Sarah January 2017 (has links)
At the moment of writing, an expansion of the Swedish railway network has started, by constructions of new lines for high-speed trains. The aim is to create a high-speed connection between the most populous cities in Sweden - Stockholm, Göteborg and Malmö, and the rest of Europe. Thereby, the likelihood of faster, longer and heavier foreign trains crossing the Swedish lines is increased. However, this could be problematic since the dynamic response in railway bridges and, consequently, the risk of resonance increases with increasing train speeds. Bridges are usually designed based on contemporary conditions and future requirements are rarely considered, due to e.g. cost issues. Prospectively, the dynamic performance of existing bridges may become insufficient. Hence, the current expansion of the high-speed railway network results in an increased demand of innovative design solutions for new bridges and cost-efficient upgrading methods for existing lines. The aim of the present thesis is to propose a vibration mitigation strategy suitable for new and existing high-speed railway bridges. The main focus is a retrofit method with fluid viscous dampers installed between the bridge superstructure and the supports, which is intended to reduce the vertical bridge deck acceleration below the European design code limits. Furthermore, the intention is to investigate the efficiency of such a system, as well as to identify and analyse the parameters and uncertainties which could influence its functionality. In order to examine the applicability of the proposed retrofit, case studies, statistical screenings and sensitivity analyses are performed and analysed. Two different models, a single-degree-of-freedom system and a finite element model, are developed and compared. From the different models, it is possible to study the influence from the damper parameters, the variability of the material properties and different modelling aspects on the bridge response. After the installation of the fluid viscous dampers, it is found that the acceleration level of the bridge deck is significantly reduced, even below the design code requirements. / I skrivande stund har en utbyggnad av det svenska järnvägsnätet initierats. Målet är att skapa en höghastighetsanslutning mellan de folkrikaste städerna i Sverige - Stockholm, Göteborg och Malmö, och vidare ut i Europa. Därmed ökar sannolikheten att snabbare, längre och tyngre utländska tåg korsar de svenska järnvägslinjerna. Dock kan detta bli problematiskt i och med att järnvägsbroars dynamiska respons och, följaktligen, risken för resonans ökar med ökad tåghastighet. Broar dimensioneras ofta utifrån nuvarande förutsättningar och hänsyn tas sällan till framtida hållbarhetskrav, exempelvis p.g.a. kostnadsbesparingar. Ur ett framtidsperspektiv kan därför det dynamiska beteendet hos befintliga broar komma att bli otillräckligt. Utbyggnaden av höghastighetsnätverket ökar därmed behovet av innovativa konstruktionslösningar för nya broar och kostnadseffektiva uppgraderingsmetoder för befintliga sträckor. Syftet med föreliggande avhandling är att föreslå en metod för att minska de vibrationsnivåer som kan uppstå i både nybyggda och befintliga järnvägsbroar för höghastighetståg. Huvudfokus är en eftermonteringsmetod med viskösa dämpare, som har installerats mellan brons överbyggnad och landfästen, för att minska brobanans vertikala acceleration under gällande europeiska dimensioneringskrav. Vidare avses att undersöka effektiveteten av ett sådant system, samt att identifiera och analysera de parametrar och osäkerheter som kan påverka dess funktionalitet. Fall- och parameterstudier, samt statistiska metoder används och utvärderas för att undersöka tillämpbarheten av den föreslagna vibrationsdämpningsmetoden. Två olika modeller, ett enfrihetsgradssystem och en finit elementmodell, har skapats och jämförts. Utifrån dessa modeller kan påverkan av dämparens parametrar, variabiliteten hos materialegenskaperna och behandlingen av olika modelleringsaspekter studeras. Från resultaten är det tydligt att brobanans accelerationsnivå avsevärt reduceras efter monteringen av viskösa dämpare, till och med under dimensioneringskraven. / <p>QC 20170425</p>
113

Stavebně technologický projekt demolice a stavby mostu / CONSTRUCTION-TECHNOLOGY PROJECT OF BRIDGE DEMOLITION AND BRIDGE CONSTRUCTION

Hofírek, Radovan January 2018 (has links)
This diploma thesis deals with the demolition of a bridge located at the D1 motorway from Prague to Brno. The bridge no longer meets the load and width requirements of today´s standards. The thesis also deals with the construction of a new bridge, which will be expanded into D28/120 category. This expansion will allow for provisory use of the carriageways of one half of the motorway in both directions. The whole reconstruction is very time consuming that is the reason the new bridge is made of prefabricated pre-tensioned girders with a composite bridge deck. This can save time and the new bridge can be open for service in a shorter period of time.
114

Visutá lávka pro pěší / Suspension footbridge

Černý, Jan January 2013 (has links)
The objective of this master's thesis is a design of suspension footbridge. The footbridge is suspended construction of stress ribbon by one span. The brick deck is supported on the edges and it is kept in a parabolic arc. The suspension cables are kept at two inclined levels. The model lengthways is implemented in the program ANSYS, by non-linear solution. The model crosswise is implemented in the program SCIA ENGINEER 2011. The design is according to relevant current standart.
115

Přemostění řeky Svitavy a tratě ČD v Blansku / Bridge crossing over Svitava river and railway track in Blansko

Smělíková, Petra January 2015 (has links)
The aim of the Diploma Thesis is elaboration of study of bridge crossing over the Svitava river and ČD railway track in Blansko. It concerns a five-pole steel beam road bridge with through-span which carries road of the third category. The static system of the construction is solved as solid-web beam of 1.3 meters height which is in three middle spans reinforced by truss construction with top chord and system of diagonals without verticals. The height of the main beam where reinforced by trusswork is 4.75 meters. The width of spans in the road axis is 18.5 + 30.525 + 44.4 + 30.525 + 18,5 metres. The bridge deck consists of steel cross beams bonded with reinforced concrete slab of 200 millimeters of thickness. The drive-through width of the roadway is 7.0 meters. The bridge is fitted with right-sided walkway placed on steel cantilevers. The walk-through width of the walkway is 3.0 meters. Material used is S355 Steel, C30/37 Concrete and S460 Steel which is used for marginal spans of the bridge. Load-bearing construction is assessed in compliance with current technical requirements laid down by European Directives, so called “Eurocodes”. The calculation of inner powers is performed using the Scia Engineer 2013.1 software.
116

Dálniční estakáda přes široké údolí / Highway multispan bridge over wide wally

Bobek, Lukáš January 2017 (has links)
The aim of this diploma thesis is to design and assess highway bridge. The structure is located on the D1 motorway section bridging a wide valley between the Slovak villages Doľany a Klčov. Three variants have been created – box girder bridge with transverse overhangs, a pair of girder bridge and a pair of box girder bridges. The various proposals were compared with each other. For the most valuable option is selected prestressed box girder bridge with transverse overhangs, which are supported by prefabricated concrete struts. The selected proposal was subsequently elaborated in detail, the load-bearing structure is analyzed using Scia Engineer 16. In calculating the internal forces is adjusted for the effects of construction methods, even as time-dependent analysis TDA. When designing the load-bearing structure it is considered the action of permanent load, also loading from transport and temperature. The structure is assessed for serviceability and ultimate limit states according to current standards. The bridge deck is built by incremental launching method. The principle of this method consists of building the segments in a casting yard located behind the bridge abutment. Each segment is matchcast against the previous one and prestressed to the section of structure already built. The whole superstructure is then jacked forward a distance equal to the length of this segment. This process is repeated until the bridge deck is in its final position. Chosen method of construction is very fast and efficient, to the country in the valley isn´t damage during construction.
117

Visutá lávka přes Labe / Suspension footbridge across the Elbe River

Gregor, Petr January 2012 (has links)
The objective of this master´s thesis is a design of suspension footbridge across the Elbe river. The footbridge is suspended construction by three spans. The brick deck is supported on the outer edges and it is kept in a parabolic arc. The suspension cables are kept at two inclined levels. The model is implemented in the program ANSYS. The solution is non-linear. The designe is according to the europien standart.
118

Lávka mezi budovami. / The bridge among buildings

Chaloupka, Petr January 2012 (has links)
This master's thesis deals with the designing of the appropriate supporting steel structure footbridge for pedestrians. The footbridge is used to connect two separate buildings (buildings D and Z at the Faculty of Civil Engineering Brno University of Technology). Four variants have been designed about solutions supporting steel structure. The final variant was prepared in detail and was carried out static assessment of the individual elements and selected details. The main supporting structure of this variant are two trusses. Diagonals of these trusses are designed linkage system of Macalloy 460. Bridge deck is designed of composite steel a concrete board with crossbars. The footbridge is designed as simple beam with an overhanging end. Length span is 34.8 m, length overhanging ends is 5.8 meters. The total length of the footbridge is 40.6 meters. Width of footbridge is 2.8 meters. Free width is 2 meters. In the cross point with the axis of local road is height of footbridge above ground 4.43 meters. Next to the building Z, there is a footbridge stored on a concrete support, near the building D, the footbridge is stored on a steel frame of support. The footbridge is deposited on elastomeric bearings. The footbridge is being protected from the weather. The sheating of the building is designed by Wictec 60 system. The master's thesis also contains drawing documentation of the proposed solution.

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