Probabilistic Risk Assessment for FPSO Topside Structures Under Drop Impact: An Application to Pipeline Protections

2011 ◽  
Author(s):  
YeongAe Heo ◽  
ByungWoo Kim ◽  
Jae-Kwang Eom
Keyword(s):  
Structural Design ◽  
Structural Damage ◽  
Hazard Analysis ◽  
Drop Impact ◽  
Structural Failure ◽  
Risk Calculation ◽  
Design Load ◽  
Fire And Explosion ◽  
Offshore Industry ◽  
Probabilistic Risk

In offshore structural design, it is necessary to evaluate probabilistic risk so that the topside structure has sufficient capacity to resist the effects of accidental loads such as drop impact, helicopter impact, vessel collision, fire, and explosion. Most engineers in the offshore industry, however, have difficulties in estimating a reliable risk value because there are still too many uncertainties in computing the probability of exceeding a target structural damage where the guideline for hazard analysis, which provides design load, is quite well described. Therefore, a framework to compute reasonable probability of structural failure is proposed in this paper. 88 impact scenarios were applied to a pipeline protection system on a topside module of Nexus genetic FPSO in order to perform regression analysis for structural damage. For risk calculation, the hazard analysis in this study is based on the detail engineering report worked by Ramboll Oil & Gas.

scholarly journals EXPERIMENTAL DATA AND NUMERICAL SIMULATION OF WAVE LOADING AND ITS REDUCTION ON SHELTERED BUILDINGS

2020 ◽  
pp. 21
Author(s):  
Joaquin Moris ◽  
Andrew Kennedy ◽  
Joannes Westerink
Keyword(s):  
Experimental Data ◽  
Numerical Simulation ◽  
Structural Design ◽  
Structural Damage ◽  
Wave Loads ◽  
Wave Loading

Wave loading from inundation events like storms and tsunamis can cause severe structural damage to buildings (Xian et al., 2015); therefore, it is important to predict wave loading as accurately as possible. One uncertainty in estimating wave loads during inundation events is the possible reduction of loads by sheltering from other buildings. Understanding and quantifying this effect could reduce overestimated loads in sheltered buildings and avoid over-conservative structural design. This work aims to quantify the reduction of wave loads in sheltered buildings through the analysis of experimental data and numerical simulations.Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/89QblLjDBnI

scholarly journals Development of a Bayesian network for probabilistic risk assessment of pesticides

2021 ◽  
Author(s):  
Sophie Mentzel ◽  
Merete Grung ◽  
Knut Erik Tollefsen ◽  
Marianne Stenrod ◽  
Karina Petersen ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Bayesian Network ◽  
Environmental Risk ◽  
Environmental Risk Assessment ◽  
Probability Distributions ◽  
Probabilistic Approach ◽  
Probabilistic Risk Assessment ◽  
Risk Calculation ◽  
Link Information ◽  
Probabilistic Risk

Conventional environmental risk assessment of chemicals is based on a calculated risk quotient, representing the ratio of exposure to effects of the chemical, in combination with assessment factors to account for uncertainty. Probabilistic risk assessment approaches can offer more transparency, by using probability distributions for exposure and/or effects to account for variability and uncertainty. In this study, a probabilistic approach using Bayesian network (BN) modelling is explored as an alternative to traditional risk calculation. BNs can serve as meta-models that link information from several sources and offer a transparent way of incorporating the required characterization of uncertainty for environmental risk assessment. To this end, a BN has been developed and parameterised for the pesticides azoxystrobin, metribuzin, and imidacloprid. We illustrate the development from deterministic (traditional) risk calculation, via intermediate versions, to fully probabilistic risk characterisation using azoxystrobin as an example. We also demonstrate seasonal risk calculation for the three pesticides.

Theoretical Assessment of Light Structural Damage due to Ship Collision With Ice

1991 ◽  
Vol 113 (1) ◽  
pp. 61-66 ◽  
Author(s):  
A. Moshaiov ◽  
M. R. Steinhilber
Keyword(s):  
Structural Design ◽  
Structural Damage ◽  
Rate Sensitivity ◽  
Marine Transportation ◽  
Design And Optimization ◽  
Ice Loads ◽  
Ship Collision ◽  
Further Development ◽  
Theoretical Assessment ◽  
Major Consideration

A major consideration in the recent development of marine transportation for ice-infested waters is the strength required for ships’ hulls. Plasticity methods are currently used in conjunction with given design ice loads. In this paper, a new plasticity model is suggested. It is based on the assumption that the kinetic energy of the ice/ship collision is absorbed both by the ice and the structure. During the collision process, the ice/structure contact area varies due to ice crushing, which dissipates some of the energy. At the same time, the plating may deform plastically, absorbing the remaining energy. Other forms of energies and ice failures are not accounted for, allowing a conservative estimate of the damage. A parametric study is performed, revealing the significance of the energy absorbed by the ice in reducing the predicted permanent deflection of the plating. The new model is shown to be useful for ship structural design and optimization in addition to the evaluation of operating restrictions. Several recommendations for further development of the model are discussed, including the incorporation of strain rate sensitivity of the ice-crushing strength and the plating yield strength.

scholarly journals Application of polyethylene air-bubble cushions to improve the shock absorption performance of Type I construction helmets for repeated impacts

2020 ◽  
pp. 1-14
Author(s):  
John Z. Wu ◽  
Christopher S. Pan ◽  
Mahmood Ronaghi ◽  
Bryan M. Wimer ◽  
Uwe Reischl
Keyword(s):  
Structural Damage ◽  
Endurance Limit ◽  
Drop Impact ◽  
Test Machine ◽  
Type I ◽  
Drop Height ◽  
Shock Absorption ◽  
Air Bubble ◽  
Absorption Performance ◽  
Repeated Impacts

BACKGROUND: The use of helmets was considered to be one of the important prevention strategies employed on construction sites. The shock absorption performance of a construction (or industrial) helmet is its most important performance parameter. Industrial helmets will experience cumulative structural damage when being impacted repeatedly with impact magnitudes greater than its endurance limit. OBJECTIVE: The current study is to test if the shock absorption performance of Type I construction helmets subjected to repeated impacts can be improved by applying polyethylene air-bubble cushions to the helmet suspension system. METHODS: Drop impact tests were performed using a commercial drop tower test machine following the ANSI Z89.1 Type I drop impact protocol. Typical off-the-shelf Type I construction helmets were evaluated in the study. A 5 mm thick air-bubble cushioning liner was placed between the headform and the helmet to be tested. Helmets were impacted ten times at different drop heights from 0.61 to 1.73 m. The effects of the air-bubble cushioning liner on the helmets’ shock absorption performance were evaluated by comparing the peak transmitted forces collected from the original off-the-shelf helmet samples to the helmets equipped with air-bubble cushioning liners. RESULTS: Our results showed that a typical Type I construction helmet can be subjected to repeated impacts with a magnitude less than 22 J (corresponding to a drop height 0.61 m) without compromising its shock absorption performance. In comparison, the same construction helmet, when equipped with an air-bubble cushioning liner, can be subjected to repeated impacts of a magnitude of 54 J (corresponding to a drop height 1.52 m) without compromising its shock absorption performance. CONCLUSIONS: The results indicate that the helmet’s shock absorbing endurance limit has been increased by 145% with addition of an air-bubble cushioning liner.

Development of a Relationship Between Residual Ultimate Longitudinal Strength Versus Grounding Damage Index Diagram for Container Ships

2012 ◽  
Author(s):  
Do Kyun Kim ◽  
Han Byul Kim ◽  
Xiaoming Zhang ◽  
Preben Terndrup Pedersen ◽  
Min Soo Kim ◽  
...  
Keyword(s):  
Structural Damage ◽  
Damage Index ◽  
International Maritime Organization ◽  
Longitudinal Strength ◽  
Fire And Explosion ◽  
Damage Criteria

Various accidents such as grounding, collision, fire, and explosion commonly occur on operating ships. The structural damage caused by such accidents is often accompanied by casualties and serious pollution. Therefore, an accidental risk-based approach that is in line with the goal-based standard of the International Maritime Organization is being developed in the literature. In the present paper, the residual ultimate longitudinal strength versus grounding damage diagram (R-D diagram) for container ships is established as per the method of Paik et al. [1]. The proposed R-D diagram should be useful for defining acceptance damage criteria and making rapid salvage plans or rescue schemes for container ships that have sustained a grounding accident.

Study on Fengdu Second Yangtze River Bridge the Cable Anchorage Structure in a Girder Transfer Mechanism

2011 ◽  
Vol 291-294 ◽  
pp. 2320-2323
Author(s):  
Xie Dong Zhang ◽  
Jin Zhi Wang ◽  
Xiao Dong Wang
Keyword(s):  
Stress Distribution ◽  
Structural Design ◽  
Yangtze River ◽  
Analysis Method ◽  
Analysis Software ◽  
Design Load ◽  
Cable Stayed Bridge ◽  
Plane Analysis ◽  
General Plane ◽  
The Common

The cable anchorage region in a girder is the key part of cable stayed bridge， in which stress distribution is rather complicated. A general plane analysis method is hard to reflect actual stress status. According to the design of Fengdu Second Yangtze River Bridge In this paper, the analysis of the spatial stress distribution of the cable anchorage structure in a girder is carried out in design load by making use of the common analysis software-Midas FEA and spatial finite element method, the verification and assessment of Fengdu Second Yangtze River Bridge Anchor Plate rational structural design is conducted, in order to put forward optimize the design suggestions, to ensure that such structures the realization of economy and reliability.

Impact Pressures on the Bottom of a Prismatic Planing Hull During Water Impact

2015 ◽  
Author(s):  
Carolyn Q. Judge ◽  
John A. Judge ◽  
Christine M. Ikeda
Keyword(s):  
Pressure Distribution ◽  
Structural Design ◽  
Structural Damage ◽  
High Speed ◽  
Empirical Method ◽  
Naval Academy ◽  
Water Impact ◽  
Empirical Estimates ◽  
Peak Pressures ◽  
The Impact

High-speed planing boats are subject to repeated slamming impacts, which can cause structural damage and discomfort or injury to passengers. The structural and seakeeping aspects of the design of high-speed craft are mainly determined through empirical estimates of mean and peak pressures. The primary structural guideline (Allen and Jones, 1978) relies heavily on semi-empirical criteria that are not always accurate and have limited application. The Allen and Jones guidelines provide conservative estimates leading to sufficient structural design, but do not provide enough guidance to allow strategic reduction in structural weight. Structural design depends on the hull bottom pressures while information about the magnitudes of peak pressures, time durations, and locations along the hull is generally not available. Model tests conducted at the US Naval Academy have measured bottom pressures on a prismatic planing hull geometry during operation in waves (both regular and irregular). Pressures were measured at point locations and using a two-dimensional pressure pad to examine how pressures change in both time and space during a water impact. Rosen (2005) presents a method for reconstructing the momentary pressure distribution during a hull-water impact. This method allows the measurements of a propagating pressure segment in one position of the hull at one instant in time to be associated with other positions at other instants in time (as determined from several different point pressure measurements). Morabito (2014) presents an empirical method for calculating the pressure distribution on the bottom of prismatic planing hulls. The method can be extended to the impact problem by use of an “equivalent” planing velocity. This paper compares the planing pressures predicted by Morabito's empirical method with the recreated pressure distribution determined from Rosen's method.

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