Browsing NTNU Open by Author "Leira, Bernt Johan"
Now showing items 61-80 of 204
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Effect of environmental modelling and inspection strategy on the optimal design of floating wind turbines
Hegseth, John Marius; Bachynski, Erin Elizabeth; Leira, Bernt Johan (Peer reviewed; Journal article, 2021)In order to reduce design conservatism and consequently the cost of energy, appropriate and cost-optimal safety factors should be derived, in light of environmental load uncertainties and lifetime costs. In the present ... -
Effect of modelling inhomogeneous wave conditions on structural responses of a very long floating bridge
Dai, Jian; Stefanakos, Christos; Leira, Bernt Johan; Alsos, Hagbart Skage (Peer reviewed; Journal article, 2021)Floating bridges are suitable for connecting land parcels separated by wide and deep waterbodies. However, when the span of the crossing becomes very long, the water environment exhibits inhomogeneities which introduce ... -
Effect of wave inhomogeneity on fatigue damage of mooring lines of a side-anchored floating bridge
Dai, Jian; Leira, Bernt Johan; Moan, Torgeir; Alsos, Hagbart Skage (Peer reviewed; Journal article, 2020)Mooring systems are important structural components of very long floating bridges. They effectively limit the transverse motions of the bridge under environmental loads. They also add viscous hydrodynamic damping to the ... -
Effect of wave-current interaction on a long fjord-crossing floating pontoon bridge
Dai, Jian; Abrahamsen, Bjørn Christian; Hansen Viuff, Thomas; Leira, Bernt Johan (Peer reviewed; Journal article, 2022)Fjord-crossing floating bridges are sophisticated structures subjected to complex environmental loadings including combined action of wave and current. However, the effect of wave-current action is often neglected in a ... -
Effect of Wave-Current Interaction on Structural Responses of a Very Long and Side-Anchored Floating Bridge
Dai, Jian; Abrahamsen, Bjørn Christian; Leira, Bernt Johan (Chapter, 2020)This paper is concerned with a computational study on the hydroelastic response of a long, straight and side-anchored fjord-crossing floating bridge accounting for the wave-current interaction. The effect of this interaction ... -
Effects of air-sea drag coefficient on estimating wind stress using wind statistics
Myrhaug, Dag; Wang, Hong; Holmedal, Lars Erik; Leira, Bernt Johan (Peer reviewed; Journal article, 2022)This article addresses the effects of the air-sea drag coefficient on estimation of wind stress based on wind statistics. This is achieved by applying the same wind stress parameterizations chosen by Wrobel-Niedzwiecka et ... -
Effects of BOP Stack Modelling on Estimated Wellhead Fatigue Damage
Harildstad, Erling; Haukanes, Andreas (Master thesis, 2013)To date, there are no international codes or standards that deal with estimation offatigue in subsea wellhead systems. Nevertheless have preliminary analytical methodsfor wellhead fatigue estimation been established. These ... -
Effects of Pretension in Bolt for a Slewing Bearing
Hossain, Md. Jahangir (Master thesis, 2014)This thesis is to check to bolt pretension for high duty bolted joint in the slewing ring. The bolted joint in the slewing ring is of special type the loads acts off axis of the bolt. For this kind of bolted joint, there ... -
Effects of soil profile variation and scour on structural response of an offshore monopile wind turbine
Li, Hui; Ong, Muk Chen; Leira, Bernt Johan; Myrhaug, Dag (Journal article, 2018)This paper presents an engineering approach to study the effects of soil profile variation and scour on structural response of an offshore monopile wind turbine. A wind-wave model for finite water depth is proposed to ... -
Effects of wave directionality on extreme response for a long end-anchored floating bridge
Viuff, Thomas; Leira, Bernt Johan; Xiang, Xu; Øiseth, Ole (Journal article; Peer reviewed, 2019)Reliable design codes are of great importance when constructing new civil engineering concepts such as floating bridges. Previously only a scarce number of floating bridges have been built in rough wave conditions and ... -
Efficient computation of cross-spectral densities in the stochastic modelling of waves and wave loads
Giske, Finn-Idar Grøtta; Leira, Bernt Johan; Øiseth, Ole (Journal article; Peer reviewed, 2017)A new method is presented for efficient calculation of auto- and cross-spectral densities in the stochastic modelling of ocean waves and wave loads. As part of the short-term response analyses, the method may contribute ... -
Eliminating the Uncertainties in Hydraulic and Ice Loads on Berm Breakwaters
Leira, Bernt Johan; Høyland, Knut Vilhelm; Pontiki, Maria (Chapter, 2019)A model for the computation of failure probabilities for partly reshaping mass-armored berm breakwaters in the Arctic is presented. The model consists of a reliable tool for the design of port structures in the rapidly ... -
Environmental contours based on inverse SORM
Chai, Wei; Leira, Bernt Johan (Journal article, 2018)It is well known that the full long-term response analysis is recognized as the most accurate and reliable method for evaluation of the extreme response in the design of ships and marine structures. However, such a method ... -
Estimating the Fatigue Life of Typical Openings in Longitudinal Strength Members in an Early Design Phase
Sissener, Jean I. Feden (Master thesis, 2020)Denne oppgaven undersøker muligheten for et forenklet beregningsverktøy for å estimere utmattings-levetiden for typiske åpninger i langsgående styrkeelementer. Verktøyet ble foreslått av VARD Group AS og er ment til å ... -
Estimation and Computation of Ice-Resistance for Ship Hulls
Thorsen, Ingvill Bryn (Master thesis, 2012)The oil price continues to increase while oil companies search for oil in new areas. There is assumed that 25% of the world s hydrocarbons are located in the arctic area. Operating in these areas will be a huge challenge ... -
Estimation of extreme response for drilling risers
Pedersen, Thor Dagfinn (Master thesis, 2013)The marine riser is an important and indispensable part of the offshore oil industry as they are used to convey fluids from the sea bed to a platform or floater. Drilling risers are used during drilling of new wells, while ... -
Estimation of the Long-Term Extreme Response of Drilling Riser by the Contour Line Method
Dashtizadeh, Leila (Master thesis, 2014)In order to design a drilling riser, it is essential to know the long-term extreme loads on the riser when it is exposed to a harsh environmental condition. Multiplying the long-term extreme response by a safety factor, ... -
Estimation of top tensions in mooring lines by sensor fusion
Sauder, Thomas Michel; Maincon, Philippe Emmanuel; Lone, Erling Neerland; Leira, Bernt Johan (Peer reviewed; Journal article, 2022)The paper describes a sensor fusion method that provides reliable, uninterrupted and bias-free estimates of the top tension in a mooring line. The method exploits the geometric nonlinearity of mooring systems installed in ... -
Estimation of VIV-parameters based on Response Measurements and Bayesian Machine Learning Algorithms
Andersen, Martin Lieberkind; Sævik, Svein; Leira, Bernt Johan; Wu, Jie; Langseth, Helge; Passano, Elizabeth Anne; Lie, Halvor; Yin, Decao (Chapter, 2022)Analysis of structural response levels due to hydro-elastic vortex-induced vibrations (VIV) involves the specification of several parameters both associated with the fluid flow and the structural properties. To the maximum ... -
Evaluation and Design of Large Precast Concrete Panels as Modules of Tanks for Smolt Breeding
Hasvåg, Thomas (Master thesis, 2015)With increasing permissions for onshore smolt breeding, the industry may long for solutions that are competitive and robust. A part of this demand relates to breeding tanks that should be able to handle the given quantity ...