The current floating bridge concepts of Norwegian Public Roads Administration (Statens vegvesen, NPRA) use a flange shape part at the bottom part of the pontoons. The flange is in principle similar to the damping plates used in the offshore industry for SPAR type of structures. The project group initiated the flange part based on the requirement of extra added mass for tuning the bridge system Eigen-modes. Thus, the important modes can be shifted out of the main wave energy zone. The current study will focus on the damping effects of such structure. The damping effects on weak axis bending moment prediction is studied. The modelling of such damping is first proposed according to relevant literature based on both numerical and experimental studies. Since the reference studies were mainly focused on cylindrical structures, it is difficult to obtain an accurate estimation of the damping coefficient for the current bridge pontoon design, which contains a rectangular part between two half-cylindrical parts. In addition, the estimation of pontoon motions needs the input of damping coefficient, which means that the evaluation of damping coefficient is an iteration process. In order to include the uncertainties, a conservative value was adopted to represent the damping effect. The comparison of accounting for the damping effects or not has been given for all the bridge pontoons. The results show that the damping effects are important at the peaks of the responses; in addition, the reduction of the predicted maximum bending moments can be expected around 10–15 percent along different positions of the bridge. However, a further investigation also shows that viscous excitation would increase the bending moments slightly. The comparison also indicates the value of further investigating the effects by CFD or model test methods.

Long floating bridges supported by pontoons with span-widths between 100m and 200m are discrete hydro-elastic structures with many critical eigenmodes. The response of the bridge girder is dominated by vertical eigenmodes and coupled horizontal modes (lateral) and rotational modes (about the longitudinal axis of the bridge girder). In this paper it is focused on design principles to reduce the response with regards to these eigenmodes. It is shown for a floating bridge with 200m span-width that by inserting a bottom flange the vertical eigenmodes can be lifted out of wind driven wave regime. It is also shown that selecting a pontoon length that give cancellation of excitation forces is beneficial, and that the geometrical shaping of the pontoon can be efficient to decrease the bridge response.

Long floating bridges supported by pontoons with span-widths between 100 m and 200 m are discrete hydro-elastic structures with many critical eigenmodes. The response of the bridge girder is dominated by vertical eigenmodes and coupled horizontal modes (lateral) and rotational modes (about the longitudinal axis of the bridge girder). This paper explores the design principles used to reduce the response with regards to these eigenmodes. It is shown for a floating bridge with 200 m span-width that by inserting a bottom flange the vertical eigenmodes can be lifted out of wind-driven wave regime. It is also shown that selecting a pontoon length that leads to cancelation of horizontal excitation forces is beneficial, and that the geometrical shaping of the pontoon can be efficient to decrease the bridge response.

<p>The distance between Norway’s second and fourth largest cities, Bergen and Stavanger, is only 150 km. The E39 link between the cities involves as per today several ferry connections, therefore the planning of a fixed connection with bridges and subsea tunnels has been going on for some years. A major technical challenge is the crossing of Bjørnafjord, since the fjord at this site is about 5000m wide and 500m deep.</p><p>This paper describes the development of technical solutions to cross the Bjørnafjord, and the evaluation and challenges met in the different stages of the project until a preferred solution was reached in 2019. Advanced analyses and evaluations have been performed to cope with challenges like wave/wind/current interactions, ship collision, parametric excitation and subsea landslides. The work performed will provide a major contribution to future largescale strait crossings in the world.</p>

The purpose of this paper is to explore different safety cultures in anchor-handling operations in the Norwegian offshore petroleum industry; how the crew and management cope with both critical and dangerous operations, compared to the periods in-between operations that are characterized by routine work. Between operations, officers function as middle managers fulfilling organizations needs for control, predictability and audit requirements. During operations, dangers and complexity demands full focus and presence towards that specific situation. Thus, the different demands are balanced by actualizing two different safety regimes and work practices. The discussion in the paper is based on two research projects conducted in 2009 and 2013, focusing on safety conditions at anchor-handling vessels.