In Norway there are plans of a ferry-free European road E39 with crossings of eight deep and wide fjords. A newly developed bridge concept that could be used for some of these fjord-crossings is a chained floating bridge. One of the challenges for the chained floating bridge is to create a convenient shipping-lane under the bridge, where one suggestion is to connect the chained floating bridge with a single pylon cable-stayed bridge. The aim of this thesis is to design and evaluate a cable-stayed bridge in connection with a chained floating bridge. The purpose is to evaluate the feasibility of such a design by conducting a case study of the crossing of Bjørnefjorden. A design of a bridge is created for the case based on a literature study of conventional cable-stayed bridges. The bridge design is modelled, analyzed and the structural integrity is evaluated with SOFiSTiK (a finite element software for structural design) according to Eurocode. The study concludes that the concept is feasible for Bjørnefjorden by providing a possible design of a cables-stayed bridge connected to a chained floating bridge with conventional cross sections. The analysis in the thesis confirms the structural integrity of the consept. The bridge design’s main span is 300m long, it has a 25m wide steel box girder where the cables (φ140mm) are placed in two planes with a spacing of 15m along the girder. It has a 184 m high A-shaped pylon with a concrete box section from the foundation up to the girder level (+50m), to the top is a steel box (3.5x3.5m). The bridge is designed with material properties according to Eurocode, where steel class S355 and concrete C45 are used. A parametric research also verifies the design’s feasibility for other geometries of chained floating bridges - where the horizontal reactions on the cable-stayed bridge vary in a range of 107MN-242MN. The parametric research confirms that both the utilization of the cross section and the stability increases with the horizontal reaction from the chained floating bridge. The parametric study also concludes that a width of 8m between the pylon legs decreases the effect on the lower part of the pylon and the support reaction at the pylon when compared with a 12m and a 18m width. However, the average utilization of the girder, cable and steel part of the pylon increases when the 8m width is compared with a 12m or a 18m wide pylon. A fan or radial cable arrangement compared to harp design is more efficient for the cables and the displacements of the girder in Z-direction. They are however, less efficient for the bottom part of the pylon than the harp arrangement. / I Norge planeras en färjefri Europaväg E39, där åtta djupa och breda fjordar ska förbindas med broar eller tunnlar. För att korsa några av fjordarna utvecklas bla. ett brokoncept med kedjeflytbro. En av utmaningarna i konceptet är att skapa en farled för fartyg under bron. Ett förslag är att koppla ihop kedjeflybron med en ”halv” snedkabelbro som har en pylon (inte två), där farleden går under huvud­spannet till snedkabelbron. Avsikten med detta examensarbete är att konstruera och utvärdera en snedkabelbro ihopkopplad med en kedjeflytbro. Syftet är att utvärdera om konceptet med snedkabelbro är genomförbart, med hjälp av en fallstudie av Bjørnefjordsförbindelsen. En konventionell design av en snedkabelbro upprättas efter fallets villkor med hjälp av en literaturstudie. Designen modelleras, analyseras och dimensioneras enligt Eurokod med analysverktyget SOFiSTiK. Slutsatsen är att konceptet med en snedkabelbro ihopkopplad med en kedjeflytbro är genomförbart då det är möjligt att designa en sådan med konventionella tvärsnitt. Analysen i rapporten bekräftar att designen har tillräcklig bärförmåga. I designen är huvudspannet 300m långt och består av en 25m bred brobalk upphängd av (φ140mm) kablar placerade i två plan var 15m. Bron har en 184m hög A-formad pylon med ett lådtvärsnitt i betong från fundament till brobalksnivån (+50m), därifrån till pylontoppen är tvärsnittet en stålbox (3.5x3.5m). Bron är dimensionerad med materialparameterar enligt Eurokod, där stålkvalitet S355 och Betong C45 har använts. En utförd parameterstudie bekräftar också konceptets genomförbarhet för andra geometrier av kedjeflytbron – där den horisontella reaktionen på snedkabelbron varierar mellan 107MN och 242MN. Parameterstudein bekräftar att både utnyttjandet av tvärsnittskapasiteten och stabiliteten ökar med den horisontella reaktionen från kedjeflytbron. Dessutom konkluderar parameterstudien att bredden 8m mellan pylonbenen minskar lasteffekten på den nedre delen av pylonen och stödreaktionen vid pylonen jämfört med bredden 12m och 18m. Däremot ökar medelutnyttjandet av tvärsnittaskapasiteten för brobalken, kablarna och ståldelen av pylonen för bredden 8m jämfört med 12m eller 18m. En radiell- eller solfjäderformad kabelkonfiguration jämfört med parallellformad design är mer effektiv för kablarna och nedböjning av brobalken. De gör däremot så att den den nedre delen av pylonen får större snittkrafter än för den parallellformade kabelkonfigurationen.

Nowadays, the Norwegian Public Roads Administration plans to replace the ferry connections along the western coast of Norway with fixed road connections through the coastal highway E39 project. Due to the necessity of bridging long distances with considerable depths, non-conventional engineering solutions are being developed. To date, the first fjord planned to be cross is Bjørnafjord, located just in the middle of Trondheim and Kristiansand. In order to bridge the fjord distance, three innovative solutions have been developed: a submerged floating tube bridge, a floating pontoon bridge, and finally, a multi-span suspension bridge. It is known that these structures are affected by periodic environmental forces which may cause significant fatigue problems in some structural components, disturbing their service behaviour. The aim of this master thesis is to deeply analyse the cumulative fatigue damage produced in the mooring lines of a proposed solution for crossing Bjørnafjorden as well as to investigate the influence of the implementation of different mooring line scenarios on the damage. A 3D finite element model of the chosen alternative was conducted and verified. The model provided the stress variations in each mooring line which were processed through Excel software using macros performed as well as Matlab scripts in order to obtain the results. Then, a deep fatigue damage assessment was carried out discussing how different tension-history time period calculations affect to the damage, as well as which fatigue evaluation methodology is adequate for the chosen solution. Moreover, the fatigue damage produced on the initial mooring line system configuration was analysed. It was investigated the repercussions of each direction and the contribution of each environmental load on the total damage. Last but not least, it was researched the influence of different water depths and line configurations on the fatigue damage. The results show that the fatigue damage obtained for the adopted solution remains far from the failure threshold with the worst damage produced in the mooring line chain components. The previous results have been computed employing a 1-hour analysis duration through the rainflow counting method. Also, the worst fatigue damage is produced by environmental states propagating in a westerly direction, corresponding to the maximum fetch. Regarding the load contribution in the fatigue damage, it is proved in this case that the current loads stabilise the mooring lines, reducing the fatigue damage. Finally, investigating the effect of various mooring line scenarios on the damage it has been proved that the fatigue damage is increased as the water depth is decreased and as the lateral mooring lines are separated from the initial configuration.