| dc.description.abstract | The ferry free E39 project includes the crossing of several demanding straits at the Norwegian west coast. Among them is the 5km wide and 600m deep Bjørnafjord located south of Bergen. To construct a floating bridge over this fjord is perhaps the largest challenge in the field of transportation in Norway in modern times. Therefore, the purposed floating bridge response due to external loadings as earthquake and tsunami should be investigated carefully.
This thesis studies the response of the side anchored floating bridge by first developing a finite element model in the finite element analysis software Abaqus. And secondly subjecting the created bridge model to seismic and tsunami loadings. The seismic loading applied consists of simulated acceleration time-histories made by Dr. Kaiming Bi. The generation of these time-histories takes the ground motion spatial variation effect which yields for long span bridges, into consideration. The field considering tsunami loads imposed on floating bridges lacks exploration. Therefore, a simplified lateral-force approach is suggested in this thesis. Due to lack of data the input time-histories for the tsunami force are based on time-histories from the 2011 Tohoku Tsunami. A combined simulation of the earthquake and tsunami load is also performed.
In the dynamic time domain analysis, it is observed that the seismic loading governs the vertical motion in the main span of the cable-stayed bridge. On the other side, the tsunami loading dominates the horizontal displacement in the floating bridge and the mooring line forces. It is also found that the bridge is capable of withstanding the loads which are assumed to be applicable for Norwegian conditions, and that with good margin with the exception of the vertical vibration under the seismic loading. When the loads are considerably increased, the response becomes critical and for some cases devastating. | |