Combination Factors Suitable for Semi-Probabilistic Design of Floating Production, Storage and Offloading (FPSO) Vessels

2006 ◽  
Author(s):  
Wenbo Huang ◽  
Torgeir Moan
Keyword(s):  
Probabilistic Models ◽  
Probabilistic Design ◽  
Wave Load ◽  
Load Combination ◽  
Load Effects

The paper derived new probabilistic models for still-water loads and the combined still-water and wave load effects of FPSOs. A procedure for determining load combination factors, which is suitable for semi-probabilistic and probabilistic design of FPSOs, is established. The most relevant load combination factors in harsh and benign conditions are derived.

Monte Carlo Prediction of the Extreme Values of the Combined Load Effect and Semi-Probabilistic Design of Ocean-Going Ships

2013 ◽  
Author(s):  
Wenbo Huang ◽  
Ying Xiao
Keyword(s):  
Monte Carlo ◽  
Extreme Values ◽  
Empirical Distribution ◽  
Extreme Value Distribution ◽  
Distribution Model ◽  
Wave Load ◽  
Load Effect ◽  
Combined Load ◽  
Load Combination ◽  
Load Effects

Based on Poisson models, the Monte Carlo simulation of the combined still-water and wave load effects is carried out to estimate extreme values of the combined load effects of oceangoing ships. The extreme values predicted are compared with those based on the theoretical methods. The numerical analyses show that the results based on the two methods agree with very well. Moreover, the empirical distribution of the combine extreme values simulated and numerical theoretical distribution based on a load combination analysis can both be well fitted to an analytical extreme value distribution model of Type II. Besides, a strength model of a ship hull beam is developed based on the fatigue analyses. Finally, with the models developed for load effect and strength, the simplified reliability analyses are carried out for an ocean going ship.

scholarly journals A study on fully nonlinear wave load effects on floating wind turbine

2019 ◽  
Vol 88 ◽  
pp. 216-240 ◽  
Author(s):  
Kun Xu ◽  
Yanlin Shao ◽  
Zhen Gao ◽  
Torgeir Moan
Keyword(s):  
Wind Turbine ◽  
Nonlinear Wave ◽  
Wave Load ◽  
Fully Nonlinear ◽  
Floating Wind Turbine ◽  
Load Effects

A New Nonslender Ringing Load Approach Verified Against Experiments

1998 ◽  
Vol 120 (1) ◽  
pp. 20-29 ◽  
Author(s):  
J. R. Krokstad ◽  
C. T. Stansberg ◽  
A. Nestega˚rd ◽  
T. Marthinsen
Keyword(s):  
Wave Model ◽  
Second Order ◽  
Wave Load ◽  
Peak Wavelength ◽  
Third Order ◽  
Load Model ◽  
Order Analysis ◽  
First Order ◽  
Load Effects ◽  
Vertical Cylinders

New results from the most recent work within the Norwegian Joint Industry Project (JIP) “Higher Order Wave Load Effects on Large Volume Structures” are presented. A nonslender theoretical model is validated from experiments for two fixed, vertical cylinders with different diameter/peak wavelength ratios. A combination of complete diffraction first-order simulations, sum and difference frequency second-order simulations, and third-order FNV (Faltinsen, Newman, and Vinje, nonlinear long wave model) is implemented in order to develop a simplified and robust ringing load model for a large range of cylinder diameter/peak wavelength ratios. Results from the full diffraction second-order analysis show a significant reduction of second-order loads compared to pure FNV in the wavelength range relevant for ringing loads. The results show improved correspondence with high-frequency experimental loads compared with the unmodified FNV. Results for different cylinder peak wavelength ratios are presented, including validation against experiments. In addition, a few simplified response simulations are carried out demonstrating significant improvements with the modified FNV model.

Uncertainty Analysis of Load Combination Factors for Global Longitudinal Bending Moments of Double-hull Tankers

2013 ◽  
Vol 57 (01) ◽  
pp. 42-58 ◽  
Author(s):  
Angelo P. Teixeira ◽  
C. Guedes Soares ◽  
Nian-Zhong Chen ◽  
Ge Wang
Keyword(s):  
Probabilistic Models ◽  
Bending Moments ◽  
Design Rules ◽  
Load Combination ◽  
Combination Methods ◽  
Reliability Method ◽  
Longitudinal Bending ◽  
Oil Tankers ◽  
Wave Induced ◽  
Double Hull

The present article aims at assessing the probabilistic characteristics of the load combination factors for global longitudinal bending moments of double-hull tankers. The calculations are performed based on a sample of oil tankers representative of the range of application of the Association of Classification Societies' (IACS)–Common Structural Rules (CSR) design rules. The article starts by reviewing the probabilistic models that have been proposed to model stillwater and wave-induced loads and their characteristic extreme values. Different load combination methods are also reviewed including an analytical method that provides the combined characteristic value of stillwater and wave-induced bending moments based on the Poisson assumption for upcrossing events and using the first-order reliability method in combination with the point-crossing method. The predictions of the different load combination methods are assessed on the basis of a sample of five oil tankers adopted during the IACS-CSR design rules development process. A parametric and an uncertainty propagation study are then performed to identify the range of variation and the probabilistic models of the load combination factors that are applicable to double-hull tankers.

Bending Capacity of Pipes Subject to Point Loads

2003 ◽  
Author(s):  
Luigino Vitali ◽  
Enrico Torselletti ◽  
Maurizio Spinazze` ◽  
Roberto Bruschi ◽  
Luca Brunetto
Keyword(s):  
Relevant Literature ◽  
Experimental Tests ◽  
Fe Model ◽  
Load History ◽  
Load Combination ◽  
Sea Bottom ◽  
Cold Bending ◽  
Strength Capacity ◽  
Bending Capacity ◽  
Load Effects

Large bending moments may develop on free pipeline lengths in the proximity of pipe sections subject to a local force. Sometimes the local force is such as to cause a partial loss of the sectional strength capacity of the pipe. This is the case of a pipeline plastically bent over the stinger of an S-lay barge, or of a pipeline laid on the sea bottom and hooked by an anchor or trawling gear, or of a pipe subject to cold bending when it is made to cope with sharp bottom roughness etc. In such conditions, the limit bending capacity of the pipe section, subject to local load effects, is significantly influenced. This aspect is not covered by international design codes and the scope of this paper is to show that, in some circumstances, it must be taken into due account. In this paper: • The relevant literature as concerns experimental tests, interpretative models, analysis methodologies and design approaches, is reviewed; • The FE model and post-processing, purpose-developed to investigate the interaction between local and global effect, are discussed; • The findings of FE analyses, in particular the effect of load combination, load history, pipe geometric characteristics and loading — magnitude and shape of the contact area, are presented. It is concluded that the limit bending capacity reduces significantly when local effects are such as to develop stresses on the pipe wall that affect the activation of the sectional buckling mechanism.

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