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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.
1

Development of a Bridge SteelEdge Beam Design : FE Modelling for a Vehicle Collision andCase Study

Ramos Sangrós, Diego January 2015 (has links)
The degradation of bridge edge beam systems in Sweden entailed the study of new alternativedesigns, which may become more optimal from a life-cycle perspective than the currenttypical solution used (concrete integrated). Subsequently, a U-shaped steel edge beamproposed by the consulting engineering group Ramböll was considered by the SwedishTransport Administration for its use in a real bridge project. This thesis follows theimplementation of this alternative in a bridge project.The goals of the thesis are to study the development of the U-shaped steel edge beam solutionin the case study, and to identify the key factors behind it. The case study consists of a roadframe bridge where a heavily damaged bridge edge beam system is going to be replaced.For the structural design of the solution, a static linear analysis of a vehicle collision has beencarried out with the help of Finite Element Modelling and current codes. The report shows themodelling of the design solution throughout different development phases in the project. Thecommercial software used has been LUSAS.As an outcome of the project, four models have been designed and analysed, two of themdeveloped by the author as proposed solutions. The factors behind the different changes in thedesign have been identified as: (1) structural resistance, (2) constructability and (3) the use ofstainless steel. Moreover, the connection between the steel edge beam and the concrete slabhas been the main critical part for the structural resistance. Finally, the current preliminarymodel at the moment this thesis is written, which was proposed in the project meetings, meetsthe requirements from a structural point of view.
2

Edge Beams : Evaluation of the Investment Cost for Its Application to Life-Cycle Cost Analysis

Kelindeman, Martti January 2014 (has links)
Edge beams in Sweden are subjected to harsh environmental conditions, such as de-icing salts and numerous freeze-thaw cycles, which result in large expenditures for the maintenance of these items. Driven by that fact, a project was initiated to investigate the life of edge beams in more detail.   The main objective of the work was to determine and provide reliable input for establishment of investment cost of edge beams. The data was later utilized in an application of life-cycle cost analysis - created by a Ph.D student. Case studies - ongoing bridge construction projects in Askersund, Rotebro and Kallhäll - gave the basis for the research. Site visits were performed and engineers were consulted for data collection.   As an outcome of the project, costs for the edge beams in the case studies were calculated and comparative charts were presented that reveal the magnitude of cost contributors to the bridge edge beam system.   The work illustrates that the construction of edge beams is a workforce demanding process. Hence it is suggested that, to find the most optimal edge beam solution in terms of investment cost and life-cycle considerations, various construction methods such as prefabrication of edge beams should be tested and analysed.
3

BRIDGE EDGE BEAM : NON-LINEAR ANALYSIS OF REINFORCEDCONCRETE OVERHANG SLAB BY FINITEELEMENT METHOD

Yaqoob, Saima January 2017 (has links)
Bridge edge beam system is an increasing concern in Sweden. Because it is the mostvisible part of the structure which is subjected to harsh weather. The edge beamcontributes to the stiffness of overhang slab and helps to distribute the concentratedload. The design of edge beam is not only affected by the structural members, but it isalso affected by non-structural members.The aim of the thesis is to investigate the influence of edge beam on the structuralbehavior of reinforced concrete overhang slab. A three-dimensional (3D) non-linearfinite element model is developed by using the commercial software ABAQUS version6.1.14. The load displacement curves and failure modes were observed. The bendingmoment and shear capacity of the cantilever slab is studied.The validated model from non-linear analysis of reinforced concrete slab gives morestiffer result and leads to the high value of load capacity when comparing with theexperimental test. The presence of the edge beam in the overhang slab of length 2.4 mslightly increases the load capacity and shows ductile behavior due to the self-weightof the edge beam. The non-linear FE-analysis of overhang slab of length 10 m leads tomuch higher load capacity and gives stiffer response as compare to the overhang slabof 2.4 m. The presence of the edge beam in the overhang slab of length 10 m giveshigher load capacity and shows stiffer response when comparing with the overhangslab of length 10 m. This might be due to the self-weight of the edge beam and theoverhang slab is restrained at the right side of the slab.
4

Undersökning av värmeförluster genom kantbalk vid användning av golvvärme : En simuleringsundersökning i COMSOL Multiphysics

Dahlin, Linus, Hedman, Marcus January 2018 (has links)
I Sverige ställs allt högre krav på nya byggnader genom bestämmelser och lagar som påverkar energianvändningen. Byggnader kan värmas upp med hjälp av olika typer av distributionssystem såsom radiatorer och golvvärme. Värmebehovet hos byggnaden baseras på hur mycket värmeenergi som behövs för att uppnå termisk komfort. För att begränsa energianvändningen används isolering i syfte att minimera värmeförlusterna genom byggnadens klimatskärm. Denna undersökning syftar till att undersöka förluster som sker genom kantbalken vid användning av vattenburet golvvärmesystem och hur dessa förluster påverkas då grundkonstruktionen tilläggsisoleras på olika sätt. Kantbalken är den förstärkta del som finns under markplattan/platta på mark, tar upp krafter från bärande väggar och finns efter sidorna på byggnaden. Golvvärme är en uppvärmningsteknik där slingor placeras i grundkonstruktionen och förser byggnader med dess värmebehov. Golvvärmesystem installeras på olika sätt beroende på byggnaders förutsättningar och är ett energieffektivt uppvärmningssätt i kombination med värmepump. Undersökningen påbörjades genom att skapa en förenklad modell som behandlar en 2-dimensionell kantbalksutformning i COMSOL Multiphysics, som är ett program för modellering där statiska och dynamiska simuleringar genomförs i modeller med hjälp av finita-elementmetoden. Fyra modeller skapades med två olika CC-mått (centrumavstånd) och två olika golvmaterial. Därefter skapades tre fall med förbättrande åtgärder för att öka kantbalkens isolerförmåga. Dynamiska simuleringar genomfördes och hade tidsintervallet 365 dagar med varierande utetemperatur. När utetemperaturen varierade var effektbehovet hos golvvärmen olika vilket ledde till att golvvärmetemperaturen justerades efter utetemperaturen för att upprätthålla samma temperatur på golvytan. Resultaten visar att kantbalken står för cirka 50 % av markkonstruktionsförlusterna med installerat L-element. Vid komplettering av konstruktionen med två fall av tillläggsisolering framkom inga större förändringar i resultaten. Genom att byta ut L-elementet till ett U-element minskar dock värmeförlusterna genom kantbalken till ca 30 %. Markkonstruktionsförluster är de förluster som överförs från byggnaden till närliggande mark. / Through laws and regulations in Sweden, increasing demands regarding energy use are affecting new buildings. A building achieving thermal comfort is attaining its thermal needs and can be done so through several types of distribution systems such as radiators and underfloor heating. Insulation is used to limit the amount of energy lost through the building’s envelope whilst keeping up with the thermal needs. This study is meant to examine the thermal leakage around the edge beam installa-tion when using a waterborne underfloor heating system and different sets of insulation are installed in the ground-related construction. The edge beam is the reinforced part located around the perimeter of the building absorbing forces from supporting walls. The study started with creating and using a simplified model in COMSOL Multiphysics to look at a two-dimensional edge beam formation. COMSOL Multiphysics is a software used for modeling different static and dynamic simulations via the finite element method. Four models were created using two different CC-dimensions (center to center distance) and two different floor materials. After this, three cases were created with improved circumstances regarding the ability to isolate heat around the edge beam. Dynamic simulations were made and calculated a year’s worth of varying outdoor temperatures. When the outdoor temperature changes, the requirements of the underfloor heating output also change which leads to its temperature adapting due to the outdoor temperature. The results indicate the edge beam related heat losses make up of about 50 % of the ground-related construction losses in the model. When completing the design with two instances of additional insulation, no major changes were found in the results. However, replacing the L-shaped insulation around the edge beam with a U-shaped insulation reduces heat losses through the edge beam to about 30 %. Ground-related construction losses are the losses transferred from the building to adjacent ground.
5

Concrete Cracks in Composite Bridges : A Case Study of the Bothnia Line Railway Bridge over Ångermanälven

Elgazzar, Hesham, Ansnaes, Viktor January 2012 (has links)
Cracks in the concrete slab of continuous composite bridges are common due to the tensile stresses at the supports. These bridges are allowed to crack as long as the cracking is controlled and not exceeding the design crack width (according to Bro 94 the crack should be injected if they are bigger than 0.2 mm). The Ångermanälven Bridge (railway bridge part of the Bothnia line project) was designed with big edge beams of width 1.2 m, 40 % of the total area of the concrete deck cross-section. During the final inspection cracks larger than the design crack width (0.3 mm according to Bro 94) were observed over the supports.In this thesis the design and the construction procedure of the bridge is studied to clarify the causes of the cracking in the edge beam. The objectives of this thesis were addressed through a literature study of the different types of cracks and the Swedish bridge codes. The expected crack width was calculate according to the same code, using a 2-D FEM model for the moment calculation, and compared with the crack width measured at the bridge.The result of the calculations shows that tensile stress due to ballast and only restraining moment due to shrinkage is not big enough to cause the measured crack width. Shrinkage force and temperature variation effects may have contributed to the concrete cracking in the edge beams. The large cross-section area of the edge beams indicates that it should be designed as part of the slab, taking that into consideration, 1.1 % reinforcement ratio in the edge beams is believed to limit the crack width to the code limits (0.3 mm).

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